Several instances of anomalously low values of the B(E2;41+→21+)B(E2;21+→0gs+) ratio (B4/2)<1 have previously been observed in several nuclei among the highly neutron deficient W-Os-Pt isotopes with even numbers of neutrons and protons. The relatively large number of cases suggests a striking new phenomenon that currently has no theoretical explanation. A clue to its origin might be achieved by comparing the B4/2 ratios in even-even nuclei with the corresponding ratios of transition rates in neighboring odd-mass nuclei. However, until now only one case (Os169) has been observed with an unusually low corresponding B4/2 ratio, approximately 1σ below 1. Electromagnetic transition rates between excited states in the extremely neutron deficient nuclide Os167 were measured using 15 single-crystal germanium detectors from the jurogam 3 array coupled to the RITU gas-filled separator. The excited states of interest were populated via the Mo92(Kr78,2pn) fusion-evaporation reaction and studied by selecting the rare reaction channel via recoil-α-decay tagging. The lifetimes of low-lying states were measured using the recoil distance Doppler shift method with the APPA plunger device. From the measured lifetimes in the rotational-like band structure assigned to the νi13/2 yrast intruder configuration, the B(E2;17/2+→13/2+) and B(E2;21/2+→17/2+) values were deduced, resulting in the ratio B(E2;21/2+→17/2+)B(E2;17/2+→13/2+)=0.49(10). The results were compared with previous measurements in the Os isotopic chain and theoretical mean-field calculations, implying that the odd neutron valence particle has limited, if any, influence on the B4/2 values for this particular single-particle configuration.

The aim of this study is to improve the characterization and modeling of the radiation field surrounding the Leksell Gamma Knife®-Perfexion^TM. The improved characterization of the radiation field enables more accurate shielding calculations to be performed for the areas adjacent to the treatment room. With the aid of a high-purity germanium detector and a satellite dose rate meter, 𝛾-ray spectra and ambient dose equivalent H*(10) data were acquired at various locations in the field of a Leksell Gamma Knife unit in a treatment room at Karolinska University Hospital, Sweden. These measurements were used to validate the results of the PEGASOS Monte Carlo simulation system with a PENELOPE kernel. The levels of the radiation that passes through the shielding of the machine (leakage radiation) are shown to be much lower than what is suggested by various bodies, e.g. the National Council on Radiation Protection and Measurements, to be used when calculating radiation shielding barriers. The results clearly indicate that Monte Carlo simulations may be used in structural shielding design calculations for γ𝛾 rays from the Leksell Gamma Knife.

Most practical guidelines for design of shielding against photon radiotherapy equipment may be retrieved from the National Council on Radiation Protection and Measurements (NCRP) report 151. The NCRP report No. 151 formalism describes structural shielding design techniques for megavoltage x- and gamma-ray radiotherapy facilities with the aim to limit radiation exposures to members of the public, employees, and the environment to an acceptable level. The implemetaion of NCRP report No. 151 recommendations may be straightforward for linear accelerators and conventional Co-60 machines which have singular source of radiation in contrast to the Leksell Gamma Knife, which has a complex multisource configuration. To harness the full potential of the NCRP 151 methodology, complementary transmission measurements may be required. In the NCRP report No. 151 the primary barriers are designed to attenuate photons emanating directly from the treatment unit while secondary barriers are calculated to shield radiation leakage and scattered photons by the patient and objects inside the treatment room. Here it is assumed that a primary radiation barrier should at the same time shield against secondary radiation. In this work the gamma-ray spectra in the vicinity of the Elekta Leksell Gamma Knife-Perfexion were acquired using a High Purity Germanium detector. It has been observed that the proportion of high energetic photons is lower in comparison with photons with low energy. This corroborates with the fact that the Leksell Gamma Knife has been designed in order to prevent any primary radiation from exiting the unit without impinging on an internal interceptor shield during all states of the machine. Therefore, the need to adapt the NCRP methodology for the Gamma Knife appeared to be justified.

PANDA (anti-proton annihiliation at Darmstadt) is planned to be one of the four main experiments at the future international accelerator complex FAIR (Facility for Antiproton and Ion Research) in Darmstadt, Germany. It is going to address fundamental questions of hadron physics and quantum chromodynamics using cooled antiproton beams with a high intensity and and momenta between 1.5 and 15 GeV/c. PANDA is designed to reach a maximum luminosity of 2 × 10³² cm⁻² s. Most of the physics programs require an excellent particle identification (PID). The PID of hadronic states at the forward endcap of the target spectrometer will be done by a fast and compact Cherenkov detector that uses the detection of internally reflected Cherenkov light (DIRC) principle. It is designed to cover the polar angle range from 5° to 22° and to provide a separation power for the separation of charged pions and kaons up to 3 standard deviations (s.d.) for particle momenta up to 4 GeV/c in order to cover the important particle phase space. This document describes the technical design and the expected performance of the novel PANDA disc DIRC detector that has not been used in any other high energy physics experiment before. The performance has been studied with Monte-Carlo simulations and various beam tests at DESY and CERN. The final design meets all PANDA requirements and guarantees sufficient safety margins.

A digital algorithm for real-time feature extraction, i.e. determination of pulse amplitude and timing, has been developed for the forward-spectrometer electromagnetic calorimeter in the PANDA experiment. The algorithm, which is based on the well known optimal-filter algorithm, has been designed to allow reconstruction of pile-up signals in real time and to work in a free-running DAQ system such as PANDA. To benchmark the algorithm, a Geant4-based Monte Carlo model of photon interactions in the calorimeter has been developed to generate realistic detector signals which were used as inputs to a VHDL simulation of the algorithm. The results of this simulation study show that the developed algorithm improves the time resolution by almost 50% compared to a conventional linear constant fraction discriminator algorithm. For the PANDA calorimeter, this results in a time root resolution close to 100 ps/ GeV per detector element at high energies. The algorithm allows reconstruction of the amplitude and timing of pile-up pulses separated by as little as 30 ns with good efficiency, fulfilling the PANDA requirements.

This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, vertical bar G(E)vertical bar and vertical bar G(M)vertical bar, using the (p) over barp -> mu(+)mu(-) reaction at PANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at PANDA, using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is (p) over barp -> pi(+)pi(-), due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented.

The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future antiProton ANnihilations at DArmstadt (PANDA or PANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in the non-perturbative regime remains one of the greatest challenges in contemporary physics. The antiproton-nucleon interaction studied with PANDA provides crucial tests in this area. Furthermore, the high-intensity, low-energy domain of PANDA allows for searches for physics beyond the Standard Model, e.g. through high precision symmetry tests. This paper takes into account a staged approach for the detector setup and for the delivered luminosity from the accelerator. The available detector setup at the time of the delivery of the first antiproton beams in the HESR storage ring is referred to as the Phase One setup. The physics programme that is achievable during Phase One is outlined in this paper.

The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N * and Delta spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N * and Delta spectra. The future antiproton experiment (P) over bar ANDA will provide direct access to final states containing a (Xi) over bar Xi pair, for which production cross sections up to mu b are expected in (p) over barp reactions. With a luminosity of L = 10(31) cm(-2) s(-1) in the first phase of the experiment, the expected cross sections correspond to a production rate of similar to 10(6) events/day. With a nearly 4 pi detector acceptance, (P) over bar ANDA will thus be a hyperon factory. In this study, reactions of the type (p) over barp -> (Xi) over bar (+)Xi*(-) as well as (p) over barp -> (Xi) over bar*(+)Xi(-) with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.

The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯p→Λ¯Λ and p¯p→Ξ¯+Ξ−. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.

PANDA is one of the four experimental pillars of the upcoming FAIR facility in Darmstadt, Germany. In PANDA, an antiproton beam with an energy between 1.5 and 15 GeV/c will interact in a hydrogen or nuclear target, allowing for studies of various aspects of non-perturbative QCD . Motivated by the high interaction rates and the diverse physics goals of the experiment, a triggerless readout approach will be employed. In this approach, each detector subsystem will be equipped with intelligent front-end electronics that independently identify signals of interest in real time. In order to detect the most forward-directed photons, electrons and positrons in PANDA, a shashlyk-type calorimeter is being constructed. This detector consists of 1512 individual cells of interleaved plastic scintillators and lead plates, and the output signals will be digitised by sampling ADCs and processed in real time by FPGAs. As part of the triggerless approach, these FPGAs will perform so-called feature extraction on the digitised signals, where the pulse-height and time of incoming pulses are extracted in real time. A substantial pile-up rate is expected, and it is foreseen that the chosen algorithm should enable reconstruction of such events. In this work we present the development of a real-time algorithm based on the well known Optimal Filter, which both improves the overall time resolution of the shashlyk detector and allows reconstruction of pile-up events with good time and energy resolution.