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  • 1. Abdou, Y.
    et al.
    Becker, K. -H
    Berdermann, J.
    Bissok, M.
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Boeser, S.
    Bothe, M.
    Carson, M.
    Descamps, F.
    Fischer-Wolfarth, J. -H
    Gustafsson, L.
    Hallgren, A.
    Heinen, D.
    Helbing, K.
    Heller, R.
    Hundertmark, S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Karg, T.
    Krieger, K.
    Laihem, K.
    Meures, T.
    Nahnhauer, R.
    Naumann, U.
    Oberson, F.
    Paul, L.
    Pohl, M.
    Price, B.
    Ribordy, M.
    Ryckbosch, D.
    Schunck, M.
    Semburg, B.
    Stegmaier, J.
    Sulanke, K. -H
    Tosi, D.
    Vandenbroucke, J.
    Wiebusch, C.
    Design and performance of the South Pole Acoustic Test Setup2012Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 683, s. 78-90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The South Pole Acoustic Test Setup (SPATS) was built to evaluate the acoustic characteristics of the South Pole ice in the 10-100 kHz frequency range, for the purpose of assessing the feasibility of an acoustic neutrino detection array at the South Pole. The SPATS hardware consists of four vertical strings deployed in the upper 500 m of the South Pole ice cap. The strings form a trapezoidal array with a maximum baseline of 543 m. Each string has seven stages equipped with one transmitter and one sensor module (glaciophone). Sound is detected or generated by piezoelectric ceramic elements inside the modules. Analogue signals are sent to the surface on electric cables where they are digitized by a PC-based data acquisition system. The data from all strings are collected on a central computer in the IceCube Laboratory from where they are sent to a central data storage facility via a satellite link or stored locally on tape. A technical overview of SPATS and its performance is presented.

  • 2.
    Adiels, Lars
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Backenstoss, G.
    Institute for Physics, University of Basle.
    Bergström, I.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Carius, S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Charalambous, S.
    Dept. of Nuclear Physics, Univerity of Tessaloniki.
    Cooper, M. D.
    Institute for Physics, University of Basle.
    Findeisen, C.
    Institute for Physics, University of Basle.
    Hatzifotiadou, D.
    Kerek, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum, Manne Siegbahn-laboratoriet.
    Papastefanou, K.
    Dept. of Nuclear Physics, Univerity of Tessaloniki.
    Pavlopoulos, P.
    Institute for Physics, University of Basle.
    Repond, J.
    Institute for Physics, University of Basle.
    Tauscher, L.
    Institute for Physics, University of Basle.
    Troester, D.
    Institute for Physics, University of Basle.
    Williams, M. C. S.
    Institute for Physics, University of Basle.
    Zioutas, K.
    Dept. of Nuclear Physics, Univerity of Tessaloniki.
    A π0 and η spectrometer of lead glass and BGO for momenta up to 1 GeV/c1986Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 244, nr 3, s. 380-390Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A spectrometer consisting of two sets of bismuth germanium oxide (BGO) crystals and a lead-glass array has been used to measure the [pi]0 and [eta] momentum spectra produced from proton-antiproton annihilations at rest. We describe the test of the BGO sets in electron beams of energies from 50 to 450 MeV. We discuss the method of construction and calibration of the lead-glass array, as well as procedures to extract the energy and position resolutions for detected photons. A momentum resolution ([sigma]) for [pi]0’s and [eta]’s of 4% and 3%, respectively has been achieved at momenta below 1 GeV/c.

  • 3. Amole, C.
    et al.
    Andresen, G. B.
    Ashkezari, M. D.
    Baquero-Ruiz, M.
    Bertsche, W.
    Bowe, P. D.
    Butler, E.
    Capra, A.
    Carpenter, P. T.
    Cesar, C. L.
    Chapman, S.
    Charlton, M.
    Deller, A.
    Eriksson, S.
    Escallier, J.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Gutierrez, A.
    Hangst, J. S.
    Hardy, W. N.
    Hayano, R. S.
    Hayden, M. E.
    Humphries, A. J.
    Hurt, J. L.
    Hydomako, R.
    Isaac, C. A.
    Jenkins, M. J.
    Jonsell, Svante
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jörgensen, L. V.
    Kerrigan, S. J.
    Kurchaninov, L.
    Madsen, N.
    Morone, A.
    McKenna, J. T. K.
    Menary, S.
    Nolan, P.
    Olchanski, K.
    Olin, A.
    Parker, B.
    Povilus, A.
    Pusa, P.
    Robicheaux, F.
    Sarid, E.
    Seddon, D.
    El Nasr, S. Seif
    Silveira, D. M.
    So, C.
    Storey, J. W.
    Thompson, R. I.
    Thornhill, J.
    Wells, D.
    van der Werf, D. P.
    Wurtele, J. S.
    Yamazaki, Y.
    The ALPHA antihydrogen trapping apparatus2014Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 735, s. 319-340Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ALPHA collaboration, based at CERN, has recently succeeded in confining cold antihydrogen atoms in a magnetic minimum neutral atom trap and has performed the first study of a resonant transition of the anti-atoms. The ALPHA apparatus will be described herein, with emphasis on the structural aspects, diagnostic methods and techniques that have enabled antihydrogen trapping and experimentation to be achieved.

  • 4. Amole, C.
    et al.
    Andresen, G. B.
    Ashkezari, M. D.
    Baquero-Ruiz, M.
    Bertsche, W.
    Burrows, C.
    Butler, E.
    Capra, A.
    Cesar, C. L.
    Chapman, S.
    Charlton, M.
    Deller, A.
    Eriksson, S.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Gutierrez, A.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Humphries, A. J.
    Isaac, C. A.
    Jonsell, Svante
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Kurchaninov, L.
    Little, A.
    Madsen, N.
    McKenna, J. T. K.
    Menary, S.
    Napoli, S. C.
    Nolan, P.
    Olchanski, K.
    Olin, A.
    Povilus, A.
    Pusa, P.
    Rasmussen, C. O.
    Robicheaux, F.
    Sacramento, R. L.
    Stracka, S.
    Sampson, J. A.
    Sarid, E.
    Seddon, D.
    Silveira, D. M.
    So, C.
    Thompson, R. I.
    Tharp, T.
    Thornhill, J.
    Tooley, M. P.
    van der Werf, D. P.
    Wells, D.
    Silicon vertex detector upgrade in the ALPHA experiment2013Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 732, s. 134-136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Silicon Vertex Detector (SVD) is the main diagnostic tool in the ALPHA-experiment. It provides precise spatial and timing information of antiproton (antihydrogen) annihilation events (vertices), and most importantly, the SVD is capable of directly identifying and analysing single annihilation events, thereby forming the basis of ALPHA's analysis. This paper describes the ALPHA SVD and its upgrade, installed in the ALPHA's new neutral atom trap.

  • 5.
    Andreassen, Björn
    et al.
    Stockholm University, Karolinska Intstitute.
    Svensson, Roger
    Holmberg, Rickard
    Danared, Håkan
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Brahme, Anders
    Karolinska Institutet, Medical Radiation Physics.
    Development of an efficient scanning and purging magnet system for IMRT with narrow high energy photon beams2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 612, nr 1, s. 201-208Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Due to the clinical advantages of Intensity Modulated Radiation Therapy (IMRT) high flexibility and accuracy in intensity modulated dose delivery is desirable to really maximize treatment outcome. Although it is possible to deliver IMRT by using broad beams in combination with dynamic multileaf collimation the process is rather time consuming and inefficient. By using narrow scanned high energy photon beams the treatment outcome can be improved, the treatment time reduced and accurate 3D in vivo dose delivery monitoring is possible by PET-CT based dose delivery imaging of photo nuclear reactions in human tissues. Narrow photon beams can be produced by directing a low emittance high energy electron beam on a thin target, and then cleaning the therapeutic photon beam from transmitted high energy electrons, and photon generated charged leptons, with a dedicated purging magnet placed directly downstream of the target. To have an effective scanning and purging magnet system the purging magnet should be placed immediately after the bremsstrahlung target to deflect the transmitted electrons to an efficient electron stopper. In the static electron stopper the electrons should be safely collected independent of the desired direction of the therapeutic scanned photon beam. The SID (Source to Isocentre Distance) should preferably be short while retaining the ability to scan over a large area on the patient and consequently there are severe requirements both on the strength and the geometry of the scanning and purging magnets. In the present study an efficient magnet configuration with a purging and scanning magnet assembly is developed for electron energies in the 50-75 MeV range and a SID of 75 cm. For a bremsstrahlung target of 3mm Be these electron energies produce a photon beam of 25-17 mm FWHM (Full Width Half Maximum) at a SID of 75 cm. The magnet system was examined both in terms of the efficiency in scanning the narrow bremsstrahlung beam and the deflection of transmitted and photon generated electrons. The simulations show that its is possible to have a scan area on the patient of up to 43 x 40 cm2 for an incident electron energy of 50 MeV and 28 x 40 cm2 at 75 MeV, while at the same time adequately deflecting the transmitted electron beam.

  • 6. Andresen, G. B.
    et al.
    Ashkezari, M. D.
    Bertsche, W.
    Bowe, P. D.
    Butler, E.
    Cesar, C. L.
    Chapman, S.
    Charlton, M.
    Deller, A.
    Eriksson, S.
    Fajans, J.
    Friesen, T.
    Fujiwara, M. C.
    Gill, D. R.
    Gutierrez, A.
    Hangst, J. S.
    Hardy, W. N.
    Hayden, M. E.
    Hayano, R. S.
    Humphries, A. J.
    Hydomako, R.
    Jonsell, Svante
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jorgensen, L. V.
    Kurchaninov, L.
    Madsen, N.
    Menary, S.
    Nolan, P.
    Olchanski, K.
    Olin, A.
    Povilus, A.
    Pusa, P.
    Sarid, E.
    el Nasr, S. Seif
    Silveira, D. M.
    So, C.
    Storey, J. W.
    Thompson, R. I.
    van der Werf, D. P.
    Yamazaki, Y.
    Antihydrogen annihilation reconstruction with the ALPHA silicon detector2012Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 684, s. 73-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ALPHA experiment has succeeded in trapping antihydrogen, a major milestone on the road to spectroscopic comparisons of antihydrogen with hydrogen. An annihilation vertex detector, which determines the time and position of antiproton annihilations, has been central to this achievement. This detector, an array of double-sided silicon microstrip detector modules arranged in three concentric cylindrical tiers, is sensitive to the passage of charged particles resulting from antiproton annihilation. This article describes the method used to reconstruct the annihilation location and to distinguish the annihilation signal from the cosmic ray background. Recent experimental results using this detector are outlined.

  • 7.
    Bargholtz, Christoph
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. kärnfysik.
    Gerén, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. kärnfysik.
    Lindberg, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. kärnfysik.
    Tegnér, Per-Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. kärnfysik.
    Zartova, Irina
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. kärnfysik.
    Kupść, A.
    Department of Nuclear and Particle Physics, Uppsala University.
    Shafigullinc, R.R:
    Moscow Engineering Physics Institute (State University), .
    Properties of the WASA pellet target and a stored intermediate-energy beam2008Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 587, nr 2-3, s. 178-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Experimental data from the reaction close to threshold have been used to investigate time-dependent properties of the WASA pellet target and the stored beam of 892.8 MeV protons in the CELSIUS accelerator. The detection of 3He ions in solid-state detectors provides an excellent almost background free trigger for η production. Pellet interactions with the surrounding material and with the beam lead to evaporation of deuterium gas into the beam pipe. Approximately 30% of the registered η decay events are due to interactions in deuterium gas outside the pellets. Due to beam–target interaction the beam is transversely heated and appears to acquire a component of a slightly lower energy.

  • 8.
    Bergeås Kuutmann, Elin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Clemént, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Eriksson, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Holmgren, Sven-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Lesser, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Nordkvist, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ramstedt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Selldén, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tylmad, Maja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Testbeam Studies of Production Modules of the ATLAS Tile  Calorimeter2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 606, s. 362-394Artikkel i tidsskrift (Fagfellevurdert)
  • 9.
    Bergeås Kuutmann, Elin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Eriksson, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Holmgren, Sven-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Lesser, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Nordkvist, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ramstedt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Selldén, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tylmad, Maja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Measurement of Pion and Proton Response and Longitudinal Shower Profiles up to 20 Nuclear Interaction Lengths with the ATLAS Tile Calorimeter2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 615, nr 2, s. 158-181Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The response of pions and protons in the energy range of 20–180 GeV, produced at CERN's SPS H8 test-beam line in the ATLAS iron–scintillator Tile hadron calorimeter, has been measured. The test-beam configuration allowed the measurement of the longitudinal shower development for pions and protons up to 20 nuclear interaction lengths. It was found that pions penetrate deeper in the calorimeter than protons. However, protons induce showers that are wider laterally to the direction of the impinging particle. Including the measured total energy response, the pion-to-proton energy ratio and the resolution, all observations are consistent with a higher electromagnetic energy fraction in pion-induced showers. The data are compared with GEANT4 simulations using several hadronic physics lists. The measured longitudinal shower profiles are described by an analytical shower parametrization within an accuracy of 5–10%. The amount of energy leaking out behind the calorimeter is determined and parametrized as a function of the beam energy and the calorimeter depth. This allows for a leakage correction of test-beam results in the standard projective geometry.

  • 10.
    Bergeås Kuutmann, Elin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Milstead, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Study of the Response of the ATLAS Central Calorimeter to Pions of Energies from 3 to 9 GeV2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 607, s. 372-386Artikkel i tidsskrift (Fagfellevurdert)
  • 11.
    Bohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Burgess, Thomas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansson, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Seo, Seon-Hee
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Wiedemann, Christin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Wikström, Gustav
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    The IceCube Data Acquisition System: Signal Capture, Digitization, and Timestamping2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 601, s. 294-316Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    IceCube is a km-scale neutrino observatory under construction at the South Pole with sensors both in the deep ice (InIce) and on the surface (IceTop). The sensors, called Digital Optical Modules (DOMs), detect, digitize and timestamp the signals from optical Cherenkov-radiation photons. The DOM Main Board (MB) data acquisition subsystem is connected to the central DAQ in the IceCube Laboratory (ICL) by a single twisted copper wire-pair and transmits packetized data on demand. Time calibration is maintained throughout the array by regular transmission to the DOMs of precisely timed analog signals, synchronized to a central GPS-disciplined clock. The design goals and consequent features, functional capabilities, and initial performance of the DOM MB, and the operation of a combined array of DOMs as a system, are described here. Experience with the first InIce strings and the IceTop stations indicates that the system design and performance goals have been achieved.

    Keywords:

  • 12.
    Bohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Johansson, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Seo, Seon-Hee
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    IceTop: The surface component of IceCube2013Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 700, s. 188-220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    IceTop, the surface component of the IceCube Neutrino Observatory at the South Pole, is an air shower array with an area of 1 km(2). The detector allows a detailed exploration of the mass composition of primary cosmic rays in the energy range from about 100 TeV to 1 EeV by exploiting the correlation between the shower energy measured in IceTop and the energy deposited by muons in the deep ice. In this paper we report on the technical design, construction and installation, the trigger and data acquisition systems as well as the software framework for calibration, reconstruction and simulation. Finally the first experience from commissioning and operating the detector and the performance as an air shower detector will be discussed.

  • 13.
    Bohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Seo, Seon Hee
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Measurement of South Pole ice transparency with the IceCube LED calibration system2013Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 711, s. 73-89Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The IceCube Neutrino Observatory, approximately 1 km(3) in size, is now complete with 86 strings deployed in the Antarctic ice. IceCube detects the Cherenkov radiation emitted by charged particles passing through or created in the ice. To realize the full potential of the detector, the properties of light propagation in the ice in and around the detector must be well understood. This report presents a new method of fitting the model of light propagation in the ice to a data set of in situ light source events collected with IceCube. The resulting set of derived parameters, namely the measured values of scattering and absorption coefficients vs. depth, is presented and a comparison of IceCube data with simulations based on the new model is shown.

  • 14.
    Bohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Seo, Seon-Hee
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    An improved method for measuring muon energy using the truncated mean of dE/dx2013Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 703, s. 190-198Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log(10)(E-mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 022 in log(10)(E-mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.

  • 15.
    Bohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Improvement in fast particle track reconstruction with robust statistics2014Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 736, s. 143-149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The IceCube project has transformed 1 km(3) of deep natural Antarctic ice into a Cherenkov detector Muon neutrinos are detected and their direction is inferred by mapping the light produced by the secondary muon track inside the volume instrumented with photomultipliers. Reconstructing the muon track from the observed light is challenging due to noise, light scattering in the ice medium, and the possibility of simultaneously having multiple muons inside the detector, resulting from the large flux of cosmic ray muons. This paper describes work on two problems: (1) the truck reconstruction problem, in which, given a set of observations, the goal is to recover the track of a muon; and (2) the coincident event problem, which is to determine how many muons are active in the detector during a time window. Rather than solving these problems by developing more complex physical models that are applied at later stages of the analysis, our approach is to augment the detector's early reconstruction with data filters and robust statistical techniques. These can be implemented at the level of on-line reconstruction and, therefore, improve all subsequent reconstructions. Using the metric of median angular resolution, a standard metric for track reconstruction, we improve the accuracy in the initial reconstruction direction by 13%. We also present improvements in measuring the number of muons in coincident events: we can accurately determine the number of muons 98% of the time.

  • 16.
    Bohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansson, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Seo, Seon-Hee
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Wikström, Gustav
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Calibration and Characterization of the IceCube Photomultiplier Tube2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 618, s. 139-152Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Over 5000 PMTs are being deployed at the South Pole to compose the IceCube neutrino observatory. Many are placed deep in the ice to detect Cherenkov light emitted by the products of high-energy neutrino interactions, and others are frozen into tanks on the surface to detect particles from atmospheric cosmic ray showers. IceCube is using the 10-in. diameter R7081-02 made by Hamamatsu Photonics. This paper describes the laboratory characterization and calibration of these PMTs before deployment. PMTs were illuminated with pulses ranging from single photons to saturation level. Parameterizations are given for the single photoelectron charge spectrum and the saturation behavior. Time resolution, late pulses and afterpulses are characterized. Because the PMTs are relatively large, the cathode sensitivity uniformity was measured. The absolute photon detection efficiency was calibrated using Rayleigh-scattered photons from a nitrogen laser. Measured characteristics are discussed in the context of their relevance to IceCube event reconstruction and simulation efforts

  • 17. Buszello, C. P.
    et al.
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Muon reconstruction and identification with the Run II D0 detector2014Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 737, s. 281-294Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an overview of the muon reconstruction and identification methods employed by the DO collaboration to analyze the Run II (2001-2011) p (p) over bar data of the Fermilab Tevatron collider at root s = 1.96 TeV. We discuss the performance of these methods, how it is measured using DO data, and how it is properly modeled by the DO simulation program. In its pseudorapidity acceptance, vertical bar eta vertical bar < 2, the muon system identifies high-p(T) muons (p(T) greater than or similar to 10 GeV) with efficiencies ranging from 72% to 89%. Muons tracks are reconstructed in the DO central tracking system with efficiencies ranging from 85% to 92% and with a typical relative momentum resolution of 10% for p(T) = 40 GeV. Isolation criteria reject multijet background with efficiencies of 87-99%.

  • 18. Collins, P.
    et al.
    Akiba, K.
    Alexander, M.
    Artuso, M.
    Bayer, F.
    van Beuzekom, M. G.
    Blusk, S.
    Bowcock, T. J. V.
    Buytaert, J.
    Campbell, M.
    Coco, V.
    Crossley, M.
    Dumps, R.
    Eklund, L.
    Esperante, D.
    Llin, L. Ferre
    Gallas, A.
    Gandelman, M.
    Gersabeck, M.
    Gligorov, V.
    Huse, T.
    John, M.
    Kucharczyk, M.
    Llopart, X.
    Maneuski, D.
    Michel, T.
    Mountain, R.
    Nichols, M.
    Papadelis, Aras
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Parkes, C.
    Plackett, R.
    Poikela, T.
    Rodrigues, E.
    Tlustos, L.
    Wang, J. C.
    Whitehead, M.
    Xing, Z.
    The LHCb VELO upgrade2011Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 636, s. S185-S193Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The LHCb experiment at the LHC plans to massively increase its data taking capabilities by running at a higher luminosity with a fully upgraded detector around 2016. This scheme is independent of (but compatible with) the plans for the SLHC upgrades. The silicon detector will be upgraded to provide a 40 MHz readout and to be able to cope with the increased radiation environment. This paper describes the options currently under consideration. A highlight of the R&D so far undertaken is a beam test during summer 2009 using the Timepix chip to track charged particles. Preliminary results are presented, including a measurement of the resolution achieved by the 55 mu m pitch pixel array of better than 9.5 mu m for perpendicular tracks and 55 mu m for angled tracks.

  • 19.
    Eriksson, Lars
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Melcher, C. L.
    Zhuravleva, M.
    Eriksson, M.
    Rothfuss, H.
    Conti, M.
    Phoswich solutions for the PET DOI problem2011Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 648, s. S288-S292Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high spatial resolution in PET can be achieved by using small detector elements. To maintain good sensitivity these elements have to be quite long, thus introducing parallax error and making the spatial resolution non-uniform over the image volume. Uniformity of spatial resolution can be improved by utilizing depth-of-interaction (DOI) information to reduce the parallax error. In the present study we have focused on phoswich approaches based on interacting scintillators, that is, a phoswich combination in which one scintillator emits light in the excitation band of the other. We have looked at LaBr3:Ce and LaCl3:Ce and the interactions of those two scintillators with LSO:Ce, GSO:Ce and YSO:Ce. The reasons to use the two Lanthanum scintillators are twofold: light output is high and the two different emission wavelengths, 350 nm (LaCl3:Ce) and 380 nm (LaBr3:Ce) may produce different interactions with the three oxyorthosilicate scintillators. In addition a possible DOI detector comprising LuAG:Pr pixels with a thin LSO:Ce layer at one end has been evaluated. A Bollinger-Thomas set-up was used to measure luminescence rise and luminescence decay time characteristics in all cases. When using LaCl3:Ce, the phoswich combinations with YSO:Ce and GSO:Ce showed phoswich decay time characteristics as expected for a simple convolution of the decay times of the two phoswich components. A correction was needed, however, for the LaCl3:Ce-LSO:Ce phoswich due to the LSO:Ce intrinsic activity. For the LaBr3:Ce-LSO:Ce phoswich, corrections were needed for noninteracting LaBr3:Ce light in addition to the expected phoswich interaction.

  • 20.
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Point source searches by IceCube: Recent results and progress2013Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 725, s. 41-44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The IceCube Neutrino Observatory began full data-taking operations in May of 2011. During the previous years of construction, data-taking was performed with each growing stage of the detector. In these proceedings we review the most recent all-sky searches for point sources of neutrinos, based on data taken between 2008 and 2010 when IceCube was operated in its 40-string and 59-string configurations. Based on better than expected performance with the partial detectors, operation of the full IceCube detector is well on track to reach the sensitivity goals for detecting high energy astrophysical neutrinos.

  • 21. Gomez-Vargas, G. A.
    et al.
    Cuoco, Alessandro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Linden, T.
    Sanchez-Conde, M. A.
    Siegal-Gaskins, J. M.
    Delahaye, T.
    Fornasa, M.
    Komatsu, E.
    Prada, F.
    Zavala, J.
    Dark matter implications of Fermi-LAT measurement of anisotropies in the diffuse gamma-ray background2014Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 742, s. 149-153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The detailed origin of the diffuse gamma-ray background is still unknown. However, the contribution of unresolved sources is expected to induce small-scale anisotropies in this emission, which may provide a way to identify and constrain the properties of its contributors. Recent studies have predicted the contributions to the angular power spectrum (APS) from extragalactic and galactic dark matter (DM) annihilation or decay. The Fermi-LAT collaboration reported detection of angular power with a significance larger than 3 sigma in the energy range from 1 GeV to 10 GeV on 22 months of data (Ackermann et al., 2012 [2]). For these preliminary results the already published Fermi-LAT APS measurements (Ackermann et al., 2012 [2]) are compared to the accurate predictions for DM anisotropies from state-of-the-art cosmological simulations as presented in Fornasa et at (2013) [1] to derive constraints on different DM candidates.

  • 22.
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ice Cube: Physics, status, and future2011Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 626, s. s6-S12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The IceCube observatory is the first cubic kilometre scale instrument in the field of high-energy neutrino astronomy and cosmic rays. In 2009, following five successful deployment seasons, IceCube consisted of 59 strings of optical modules in the South Pole ice, together with 118 air shower detectors in the IceTop surface array. The range of physics topics includes neutrino signals from astrophysical sources, dark matter, exotic particle physics, cosmic rays, and atmospheric neutrinos. The current IceCube status and selected results are described. Anticipated future developments are also discussed, in particular the Deep Core low energy subarray which was recently deployed.

  • 23. Jen-La Plante, Imai
    et al.
    Tylmad, Maja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Pulse shapes for signal reconstruction in the ATLAS Tile Calorimeter2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 617, nr 03-jan, s. 96-98Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ATLAS detector will record proton-proton collisions produced in the Large Hadron Collider at center of mass energies of up to 14 TeV. Its design allows for precision measurements as well as searches for new physics. Energy measurement using the calorimeters is crucial to these efforts. Studies of the pulse shapes used for signal reconstruction in the Tile Calorimeter are presented. The shapes were measured using test beam data and found to vary slightly with signal size. The impact of this variation on the reconstructed energy has been determined using a toy Monte Carlo.

  • 24. Kanai, Y.
    et al.
    Ueno, M.
    Kataoka, J.
    Arimoto, M.
    Kawai, N.
    Yamamoto, K.
    Mizuno, T.
    Fukazawa, Y.
    Kiss, M.
    Ylinen, T.
    Bettolo, C. Marini
    Carlson, P.
    Klamra, W.
    Pearce, M.
    Chen, P.
    Craig, B.
    Kamae, T.
    Madejski, G.
    Ng, J. S. T.
    Rogers, R.
    Tajima, H.
    Thurston, T. S.
    Saito, Y.
    Takahashi, T.
    Gunji, S.
    Björnsson, Claes-Ingvar
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Ryde, F.
    Stockholms universitet.
    Bogaert, G.
    Kishimoto, S.
    Beam test of a prototype phoswich detector assembly for the PoGOLite astronomical soft gamma-ray polarimeter2007Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 570, nr 1, s. 61-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report about the beam test on a prototype of the balloon-based astronomical soft gamma-ray polarimeter, PoGOLite (Polarized Gamma-ray Observer-Light Version) conducted at KEK Photon Factory, a synchrotron radiation facility in Japan. The synchrotron beam was set at 30, 50, and 70 keV and its polarization was monitored by a calibrated polarimeter. The goal of the experiment was to validate the flight design of the polarimeter. PoGOLite is designed to measure polarization by detecting a Compton scattering and the subsequent photo-absorption in an array of 217 well-type phoswich detector cells (PDCs). The test setup included a first flight model PDC and a front-end electronics to select and reconstruct valid Compton scattering events. The experiment has verified that the flight PDC can detect recoil electrons and select valid Compton scattering events down to 30 keV from background. The measure azimuthal modulations (34.4%, 35.8% and 37.2% at 30, 50, and 70 keV, respectively) agreed within 10% (relative) with the predictions by Geant4 implemented with dependence on the initial and final photon polarizations.

  • 25.
    Kastlander, Johan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bargholtz, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Efficient in situ method to determine radionuclide concentration in soil2005Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 547, nr 2-3, s. 400-410Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A simple realisation of the so-called peak-to-valley method is described combining simulations of photon transport in soil with measured detector properties. Comparisons regarding the total activity of Cs-137 determined from gamma spectra recorded in situ to results from soil sampling show excellent agreement for six different sites in Sweden with different surface properties and activities ranging from 15 to 1000 kBq/m(2). These results are quite insensitive to assumptions regarding soil composition. Our results for the burial depth are more sensitive to assumptions regarding soil composition, however, still in general agreement with the results from the soil samples.

  • 26.
    Kastlander, Johan
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bargholtz, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Investigation into the properties of CdTe detectors for in-situ measurements2008Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 596, nr 3, s. 409-416Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As part of a program investigating means to improve gamma-ray spectra obtained with CdTe detectors, we report results obtained with two 10×10×5 mm^3 CdTe detectors, one planar the other of quasi-hemispheric geometry. Applying a combination of cooling and pulse rise-time discrimination with the quasi-hemispheric detector, we obtain a resolution of 4 percent at 662 keV and a peak-to-valley ratio of 92 at a loss of approximately 25 percent of the counts in the full-energy region.

  • 27.
    Liu, Yuwen
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hobein, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Solders, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Suhonen, Markus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Schuch, Reinhold
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Improved temperature regulation of Penning trap mass spectrometers2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 294, nr 1, s. 28-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to reach relative uncertainties in mass measurements with Penning traps of 10-10 or better, the temperature variation of the trap and surrounding materials must be kept below 10 mK. Temperature variations induce a shift in the measured ion cyclotron frequency because of non-zero, temperature dependent magnetic susceptibilities of the construction materials. In this paper we report of a new temperature regulation system recently installed at SMILETRAP II that manages to keep the temperature fixed at the set point with a standard deviation of only 2.6 mK. −10 or better, the temperature variation of the trap and surrounding.

  • 28. Lorente, A. Sanchez
    et al.
    Achenbach, P.
    Agnello, M.
    Bressani, T.
    Bufalino, S.
    Cederwall, B.
    Feliciello, A.
    Ferro, F.
    Gerl, J.
    Iazzi, F.
    Kavatsyuk, M.
    Kojouharov, I.
    Majling, L.
    Pantaleo, A.
    Palomba, M.
    Pochodzalla, J.
    Raciti, G.
    Saito, N.
    Saito, T. R.
    Schaffner, H.
    Sfienti, C.
    Szymanska, K.
    Tegner, Per - Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Performance of HPGe detectors in high magnetic fields2007Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 573, nr 3, s. 410-417Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new generation of high-resolution hypernuclear gamma-spectroscopy experiments with high-purity germanium detectors (HPGe) are presently designed at the FINUDA spectrometer at DA Phi NE, the Frascati phi-factory, and at (P) over bar ANDA, the (p) over barp hadron spectrometer at the future FAIR facility. Both, the FINUDA and (P) over bar ANDA spectrometers are built around the target region covering a large solid angle. To maximise the detection efficiency the HPGe detectors have to be located near the target, and therefore they have to be operated in strong magnetic fields (B approximate to I T). The performance of HPGe detectors in such an environment has not been well investigated so far. In the present work VEGA and EUROBALL Cluster HPGe detectors were tested in the field provided by the ALADiN magnet at GSI. No significant degradation of the energy resolution was found, and a change in the rise time distribution of the pulses from preamplifiers was observed. A correlation between rise time and pulse height was observed and is used to correct the measured energy, recovering the energy resolution almost completely. Moreover, no problems in the electronics due to the magnetic field were observed.

  • 29.
    Makonyi, Karoly
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Marcks von Würtemberg, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tegnér, Per-Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hansen, K.
    Isaksson, L.
    Lundin, M.
    Schroder, B.
    Balkeståhl, L.
    Fransson, K.
    Johansson, T.
    Rosenbaum, C.
    Wolke, M.
    Erni, W.
    Keshelashvili, I.
    Krushe, B.
    Evaluating vacuum phototriodes designed for the PANDA electromagnetic calorimeter2014Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 763, s. 36-43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work properties of a vacuum phototriode (VPT) and preamplifier unit designed for the electromagnetic calorimeter of the PANDA experiment being built at FAIR are investigated. With the use of lead tungstate and lanthanium bromide scintillators the VPT properties are studied at low photon energies, from tens of key in the lanthanium bromide measurements and between 10 MeV and 60 MeV in the lead tungstate measurements. At these energies the noise of the VPT unit can be expected to influence its performance significantly. It is shown that the noise contribution to the measured energy resolution, under optimal conditions, is consistent with a fluctuation of (one standard deviation) approximately 200 electrons at the VPT anode. For a lead tungstate crystal this is equivalent to a noise of 1.2 MeV. For lanthanium bromide this makes it possible to use VPTs for gamma ray spectroscopy above a few hundreds of keV without noticeable effects on the energy resolution compared to measurements with a standard photomultiplier.

  • 30.
    Marcks von Wurtemberg, Klas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Geren, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Lundberg, Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tegnér, Per-Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Fransson, K.
    Grape, S.
    Johansson, T.
    Thome, E.
    Wolke, M.
    Brudvik, J.
    Fissum, K.
    Hansen, K.
    Isaksson, L.
    Lundin, M.
    Schroder, B.
    The response of lead-tungstate scintillators (PWO) to photons with energies in the range 13 MeV-64 MeV2012Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 679, s. 36-43Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The response of a matrix of 25 lead tungstate (PWO) scintillator detectors, operated at -25 degrees C, to photons in the range 13 MeV-64 MeV has been measured at the tagged-photon facility at MAX-lab, Lund. The tapered PWO crystals, each with a length of 200 mm and a cross-section of 24.4 x 24.4 mm(2) in the front end, read out by 19 mm photomultiplier tubes, were arranged in a 5 x 5 matrix. The response was measured for photons directed towards the centre of the central crystal as well as for photons directed towards the corner of the central crystal, where four crystals meet. The obtained energy resolution surpasses what has been published so far and is close to the limit given by Poisson statistics and escaped energy. For photons directed towards the centre(corner) of the central crystal the relative energy resolution, defined as (FWHM/2.35)/E-gamma, decreases from 7.3%(11.0%) at E-gamma = 13 MeV to 3.3%(3.6%) at E-gamma = 64 MeV. The reconstructed point of impact of a photon in this energy range is determined with an uncertainty (one standard deviation) of 7.3 +/- 0.1 mm.

  • 31. Mizuno, T.
    et al.
    Kanai, Y.
    Kataoka, J.
    Kiss, M.
    Kurita, K.
    Pearce, M.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Ueno, M.
    Umeki, Y.
    Yoshida, H.
    Arimoto, M.
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Bettolo, C. Marini
    Bogaert, G.
    Chen, P.
    Craig, W.
    Fukazawa, Y.
    Gunji, S.
    Kamae, T.
    Katsuta, J.
    Kawai, N.
    Kishimoto, S.
    Klamra, W.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Madejski, G.
    Ng, J. S. T.
    Ryde, F.
    Rydström, S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Takahashi, T.
    Thurston, T. S.
    Varner, G.
    A Monte Carlo method for calculating the energy response of plastic scintillators to polarized photons below 100 keV2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 600, nr 3, s. 609-617Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The energy response of plastic scintillators (Eljen Technology EJ-204) to polarized soft gamma-ray photons below 100 keV has been studied, primarily for the balloon-borne polarimeter, PoGOLite. The response calculation includes quenching effects due to low-energy recoil electrons and the position dependence of the light collection efficiency in a 20 cm long scintillator rod. The broadening of the pulse-height spectrum, presumably caused by light transportation processes inside the scintillator, as well as the generation and multiplication of photoelectrons in the photomultiplier tube, were studied experimentally and have also been taken into account. A Monte Carlo simulation based on the Geant4 toolkit was used to model photon interactions in the scintillators. When using the polarized Compton/Rayleigh scattering processes previously corrected by the authors, scintillator spectra and angular distributions of scattered polarized photons could clearly be reproduced, in agreement with the results obtained at a synchrotron beam test conducted at the KEK Photon Factory. Our simulation successfully reproduces the modulation factor, defined as the ratio of the amplitude to the mean of the distribution of the azimuthal scattering angles, within similar to 5% (relative). Although primarily developed for the PoGOLite mission, the method presented here is also relevant for other missions aiming to measure polarization from astronomical objects using plastic scintillator scatterers. 

  • 32. Murin, Yu.
    et al.
    Babain, Yu.
    Chubarov, M.
    Tuboltsev, Yu.
    Pljuschev, V.
    Zubkov, M.
    Nomokonov, P.
    Voronin, A.
    Merkin, M.
    Kondratiev, V.
    Olsson, N.
    Blomgren, J.
    Westerberg, L.
    Ekstroem, C.
    Kolozhvari, A.
    Jaederstroem, H.
    Jakobsson, B.
    Golubev, P.
    Bargholz, Chr.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Geren, L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tegner, P. -E
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Zartova, I.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Budzanowski, A.
    Czech, B.
    Skwirczynska, I.
    Tang, H. H. K.
    A detector system for studying nuclear reactions relevant to Single Event Effects2007Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 578, nr 2, s. 385-398Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We describe a device to study reactions relevant for the Single Event Effect (SEE) in microelectronics by means of 200A and 300AMeV, inverse kinematics, Si + H and Si + D reactions. The work is focused on the possibility to measure Z = 2-14 projectile fragments as efficiently as possible. During commissioning and first experiments the fourth quadrant of the CELSIUS storage ring acted as a spectrometer to register fragments in two planes of Si strip detectors in the angular region 0 degrees-0.6 degrees. A combination of ring-structured and sector-structured Si strip detector planes operated at angles 0.6 degrees-1.1 degrees. For specific event tagging a Si+ phoswich scintillator wall operated in the range 3.9 degrees-11.7 degrees and Si Delta E-E telescopes of CHICSi type operated at large angles.

  • 33.
    Nygren, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    High-Pressure Xenon Gas Electroluminescent TPC for $0-\nu \beta\beta$-Decay Search2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 603, s. 337-348Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high-pressure xenon gas TPC can provide both event topology information and optimized energy resolution for the detection of ββ decay in 136Xe. The result of optimization indicates that, at the 136Xe Q-value of 2480 keV, an energy resolution of δE/E<5×10−3 FWHM may be realizable, even at the 1000 kg scale. Signal detection by electroluminescence appears essential to realize this performance. A specific method for generation and detection of the electroluminescent signal and particle tracking in high-pressure xenon gas is advanced. Strengths and weaknesses of high-pressure xenon gas TPC detectors are evaluated and compared to detectors based on liquid xenon

  • 34.
    Ohm, Christian
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Pauly, T.
    European Organization for Nuclear Research, 1211 Genève, Switzerland.
    The ATLAS beam pick-up based timing system2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 623, nr 1, s. 558-560Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ATLAS BPTX stations are composed of electrostatic button pick-up detectors, located 175 m away along the beam pipe on both sides of ATLAS. The pick-ups are installed as a part of the LHC beam instrumentation and used by ATLAS for timing purposes.

    The usage of the BPTX signals in ATLAS is twofold: they are used both in the trigger system and for LHC beam monitoring. The BPTX signals are discriminated with a constant-fraction discriminator to provide a Level-1 trigger when a bunch passes through ATLAS. Furthermore, the BPTX detectors are used by a stand-alone monitoring system for the LHC bunches and timing signals. The BPTX monitoring system measures the phase between collisions and clock with a precision better than 100 ps in order to guarantee a stable phase relationship for optimal signal sampling in the sub-detector front-end electronics. In addition to monitoring this phase, the properties of the individual bunches are measured and the structure of the beams is determined.

    On September 10, 2008, the first LHC beams reached the ATLAS experiment. During this period with beam, the ATLAS BPTX system was used extensively to time in the read-out of the sub-detectors. In this paper, we present the performance of the BPTX system and its measurements of the first LHC beams.

  • 35. Pleskac, R.
    et al.
    Abou-Haidar, Z.
    Agodi, C.
    Alvarez, M. A. G.
    Aumann, T.
    Battistoni, G.
    Bocci, A.
    Böhlen, T. T.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Boudard, A.
    Brunetti, A.
    Carpinelli, M.
    Cirrone, G. A. P.
    Cortes-Giraldo, M. A.
    Cuttone, G.
    De Napoli, M.
    Durante, M.
    Fernandez-Garcia, J. P.
    Finck, C.
    Golosio, B.
    Gallardo, M. I.
    Iarocci, E.
    Iazzi, F.
    Ickert, G.
    Introzzi, R.
    Juliani, D.
    Krimmer, J.
    Kurz, N.
    Labalme, M.
    Leifels, Y.
    Le Fevre, A.
    Leray, S.
    Marchetto, F.
    Monaco, V.
    Morone, M. C.
    Oliva, P.
    Paoloni, A.
    Piersanti, L.
    Quesada, J. M.
    Raciti, G.
    Randazzo, N.
    Romano, F.
    Rossi, D.
    Rousseau, M.
    Sacchi, R.
    Sala, P.
    Sarti, A.
    Scheidenberger, C.
    Schuy, C.
    Sciubba, A.
    Sfienti, C.
    Simon, H.
    Sipala, V.
    Spiriti, E.
    Stuttge, L.
    Tropea, S.
    Younis, H.
    Patera, V.
    The FIRST experiment at GSI2012Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 678, s. 130-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at the SIS accelerator of GSl laboratory in Darmstadt has been designed for the measurement of ion fragmentation crosssections at different angles and energies between 100 and 1000 MeV/nucleon. Nuclear fragmentation processes are relevant in several fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The start of the scientific program of the FIRST experiment was on summer 2011 and was focused on the measurement of 400 MeV/nucleon C-12 beam fragmentation on thin (8 mm) graphite target. The detector is partly based on an already existing setup made of a dipole magnet (ALADiN). a time projection chamber (TP-MUSIC IV), a neutron detector (LAND) and a time of flight scintillator system (TOFWALL). This pre-existing setup has been integrated with newly designed detectors in the Interaction Region, around the carbon target placed in a sample changer. The new detectors are a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger scintillator system optimized for the detection of light fragments emitted at large angles. In this paper we review the experimental setup, then we present the simulation software, the data acquisition system and finally the trigger strategy of the experiment.

  • 36.
    Reinhed, Peter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Orbán, Andrea
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Rosén, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Thomas, Richard
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Kashperka, Iryna
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansson, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Misra, Deepankar
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Fardi, Afshin
    Brännholm, Lars
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Björkhage, Mikael
    Stockholms universitet, Naturvetenskapliga fakulteten, Manne Siegbahn-laboratoriet.
    Cederquist, Henrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Schmidt, Henning
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Cryogenic keV ion-beam storage in ConeTrap - a tool for ion-temperature control2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 621, nr 1-3, s. 83-90Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have tested the ion-storage capabilities of the compact triple-electrode electrostatic ion-beam trap, ConeTrap, down to cryogenic temperatures. The low-temperature operation of this electrostatic storage device is an important test for the double electrostatic ion-ring experiment, DESIREE, which is presently under construction at Stockholm University. In the present work we measured the pressure dependent storage lifetimes of 2.5 keV He+ and 2.8 keV Ar+ ion beams in ConeTrap at temperatures down to 28 K and pressures down to 1.3·10-10 mbar. The so far longest measured ion storage lifetime using this system is 21.5±3.8 s for Ar+ ions. The present combination of ConeTrap and the cryogenic experimental chamber was recently applied in the first black-body correction-free measurement of the lifetime of the metastable He- ion at 10 K [Phys. Rev. Lett. 103, 213002(2009)].

  • 37. Shayduk, M.
    et al.
    Mirzoyan, R.
    Kurz, M.
    Knötig, M.
    Bolmont, J.
    Dickinson, Hugh
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Lorenz, E.
    Tavernet, J. -P
    Hose, J.
    Teshima, M.
    Vincent, P.
    Light sensors selection for the Cherenkov Telescope Array: PMT and SiPM2012Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 695, s. 109-112Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Cherenkov Telescope Array (CIA) is planned as the next generation ground-based instrument (after VERITAS, H.E.S.S. and MAGIC) for astrophysics by means of very high energy gamma-rays. The CIA collaboration includes the MAGIC, the H.E.S.S. and the VERITAS collaborations. Also, a large number of astrophysicists from European institutions, from Japan and USA have joined the CIA. The CIA array will comprise about 100 imaging telescopes of three sizes that shall provide one order of magnitude higher sensitivity than the current generation of telescopes. Every telescope will use an imaging camera based on similar to 2000 PMTs. We have set up a PMT development program with Hamamatsu (Japan) and Electron Tube Enterprises (England) aiming to produce 1.5 in. PMTs of optimized parameters for the CIA project. The entire scientific community, including the medicine and biology, as well as many industrial applications, where a low light level sensors are necessary, may profit from it. Together with PMTs also SiPMs are interesting sensor candidates for the CIA telescopes. One expects about two times higher photon detection efficiency for SiPM compared to PMT. A set of parameters like the photon detection efficiency, cross-talk, afterpulsing, dark rate together with other important factors were evaluated. Here we report on the progress of these developments, based on detailed measurements.

  • 38.
    Tashenov, Stanislav
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Circular polarimetry with gamma-ray tracking detectors2011Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 640, nr 1, s. 164-169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Measurement of circular polarization of gamma-rays with position sensitive solid state detectors is proposed. It is based on the transfer of the photon spin to the recoiled electron in the process of Compton scattering and subsequent detection of the electron spin polarization. Bremsstrahlung polarization correlations, in particular the left-right asymmetry of the photon emission from transversally polarized electrons, are used for this purpose. Compton scattering and electron bremsstrahlung events as well as the scattered and the bremsstrahlung photon absorptions take place inside the active volume of the position sensitive detector. These events are identified and their complete kinematics is reconstructed by means of gamma-ray tracking. No spin polarized targets and no inactive materials are needed for this technique. The proposed method is naturally integrated into the concept of a Compton telescope, allowing for the first time to build an imaging gamma-ray circular polarimeter. It should work in the energy region of several 100 key up to several 10 MeV.

  • 39.
    Tashenov, Stanislav
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Royal Institute of Technology, Sweden; Helmholtz Association, Germany.
    Gerl, J.
    TANGO-New tracking AlGOrithm for gamma-rays2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 622, nr 3, s. 592-601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For spectroscopy, polarimetry and imaging purposes a new gamma-ray tracking algorithm has been developed featuring identification of Compton escape events. The rejection of these events results in a significant increase of the Peak/Total ratio. The initial photon energy is restored for these events. Although the energy resolution in the spectrum reconstructed from the escape events is lower than the one from the full-energy events, the Monte-Carlo simulations show that the combined spectrum has an increased detector full-energy efficiency of up to 130% compared to its intrinsic full-energy efficiency. The assumed geometrical origin of the photons is verified event-by-event. This enables separation of photons emitted from a target and from background sources. A linear polarization analysis of the gamma-lines can be performed. The efficiency of the algorithm and the Peak/Total ratio depending on the detector properties is discussed along with the proposed optimization schemes. The influence of the intrinsic properties of the scattering process like Compton profile and electron recoiling is discussed as well. The described algorithm deals with single photon events with energies of approximate to 100 keV up to a few MeV.

  • 40.
    Valdes Santurio, Eduardo
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Beam tests on the ATLAS tile calorimeter demonstrator module2019Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 936, s. 115-116Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The Large Hadron Collider (LHC) Phase-II upgrade aims to increase the accelerator luminosity by a factor of 5-10. Due to the expected higher radiation levels and the aging of the current electronics, a new read-out system of the ATLAS experiment hadronic calorimeter (TileCal) is needed. A Demonstrator prototype of the electronics has been tested during different testbeam campaigns at the Super Proton Synchrotron (SPS) accelerator of CERN with the purpose of checking the calibration and determining the performance of the detector by exploiting the features of the interactions of different particles with matter. We present the current status and results where the Demonstrator new electronics were situated in calorimeter modules and data were collected by exposing it to beams of muons, electrons and hadrons, at various incident energies and impact angles.

  • 41. Viel, Simon
    et al.
    Banerjee, Swagato
    Brandt, Gerhard
    Carney, Rebecca
    Lawrence Berkeley National Laboratory and University of California, United States of America.
    Garcia-Sciveres, Maurice
    Hard, Andrew Straiton
    Kaplan, Laser Seymor
    Kashif, Lashkar
    Pranko, Aliaksandr
    Reiger, Julia
    Wolf, Julian
    Wu, Sau Lan
    Yang, Hongtao
    Performance of silicon pixel detectors at small track incidence angles for the ATLAS Inner Tracker Upgrade2016Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 831, s. 254-259Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to enable the ATLAS experiment to successfully track charged particles produced in high-energy collisions at the High-Luminosity Large Hadron Collider, the current ATLAS Inner Detector will be replaced by the Inner Tracker (ITk), entirely composed of silicon pixel and strip detectors. An extension of the tracking coverage of the ITk to very forward pseudorapidity values is proposed, using pixel modules placed in a long cylindrical layer around the beam pipe. The measurement of long pixel clusters, detected when charged particles cross the silicon sensor at small incidence angles, has potential to significantly improve the tracking efficiency, fake track rejection, and resolution of the ITk in the very forward region. The performance of state-of-the-art pixel modules at small track incidence angles is studied using test beam data collected at SLAC and CERN.

  • 42.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    A Novel Method for Modeling the Recoil in W Boson Events at Hadron Colliders2009Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 609, s. 250-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a new method for modeling the hadronic recoil in W→ℓν events produced at hadron colliders. The recoil is chosen from a library of recoils in Z→ℓℓ data events and overlaid on a simulated W→ℓν event. Implementation of this method requires that the data recoil library describe the properties of the measured recoil as a function of the true, rather than the measured, transverse momentum of the boson. We address this issue using a multidimensional Bayesian unfolding technique. We estimate the statistical and systematic uncertainties from this method for the W boson mass and width measurements assuming

    of data from the Fermilab Tevatron. The uncertainties are found to be small and comparable to those of a more traditional parameterized recoil model. For the high precision measurements that will be possible with data from Run II of the Fermilab Tevatron and from the CERN LHC, the method presented in this paper may be advantageous, since it does not require an understanding of the measured recoil from first principles

  • 43.
    Åsman, Barbro
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    The DØ Silicon Microstrip Tracker2011Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 634, nr 1, s. 8-46Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper describes the mechanical design, the readout chain, the production, testing and the installation of the Silicon Microstrip Tracker of the D0 experiment at the Fermilab Tevatron collider. In addition, we describe the performance and operational experience of the detector during the experiment data collection between 2001 and 2010.

  • 44.
    Åsman, Barbro
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Belanger-Champagne, C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    b-Jet Identification in the D0 Experiment2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 620, s. 490-517Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron collider. This article describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.

  • 45.
    Åsman, Barbro
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bergeås Kuutmann, Elin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Clément, Christophe
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Eriksson, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Gellerstedt, Karl
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hellman, Sten
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hidvégi, Attila
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Hillert, Sonja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Holmgren, Sven-Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansen, Marianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Johansson, Erik
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Jon-And, Kerstin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Lesser, Jonas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Milstead, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Moa, Torbjörn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Nordkvist, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Ramstedt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Selldén, Björn
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Silverstein, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Sjölin, Jörgen
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Tylmad, Maja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Yang, Zhaoyu
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Study of Energy Response and Resolution of the ATLAS Barrel Calorimeter to Hadrons of Energies from 20 to 350 GeV2010Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 621, nr 1-3, s. 134-150Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report on the results of the search for extremely-high energy neutrinos with energies above 107 GeV obtained with the partially (∼30%) constructed IceCube in 2007. From the absence of signal events in the sample of 242.1 days of effective live time, we derive a 90% C.L. model independent differential upper limit based on the number of signal events per energy decade at E2ϕνeμτ≃1.4×10-6 GeV cm-2 sec⁡-1 sr-1 for neutrinos in the energy range from 3×107 to 3×109 GeV

1 - 45 of 45
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