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Åkerstedt, Henrik
Publications (10 of 420) Show all publications
Åkerstedt, H. (2024). Demonstrating reliableinstrumentation in theATLAS Tile Calorimeter: Fault tolerance and redundancy in hardware and firmwarefor the Phase-II Demonstrator project in preparation forHigh Luminosity LHC at CERN. (Licentiate dissertation). Stockholm: Department of Physics, Stockholm University
Open this publication in new window or tab >>Demonstrating reliableinstrumentation in theATLAS Tile Calorimeter: Fault tolerance and redundancy in hardware and firmwarefor the Phase-II Demonstrator project in preparation forHigh Luminosity LHC at CERN
2024 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The Large Hadron Collider at CERN is scheduled to undergo upgrades in 2026-2028 to significantly increase its luminosity. These upgrades, while providing the experiments with a higher collision rate, pose a number of challenges to the design of the hardware and software in the detectors. The Tile Calorimeter (a scintillating sampling calorimeter read out by photomultiplier tubes) at the ATLAS experiment will have its read-out electronics completely replaced to enable performance and reliability improvements. 

Advances in electronics, new requirements due to the luminosity upgrade as well as lessons learned from the current readout scheme drove development with the goals to partition the readout into small independent units with full granularity readout and a robust mitigation strategy for radiation induced errors. To verify the functionality of the new system while retaining backward compatibility a "Demonstrator'' has been developed to emulate the current functionality while using new and improved hardware.

The board responsible for managing digitized calorimeter data and communicating with the off-detector electronics, called the DaughterBoard, is the main focus of this thesis. It has two electrically isolated sides for redundancy where each side consists of voltage regulators, two optical transceivers, a GigaBit transceiver chip (for clocking and configuration) and a Kintex FPGA for data processing.

In addition to data management and transmission, the FPGA (and every other component) needs to be able to withstand the effects of radiation both in terms of total dose (ionization and displacement damage) and due to single event effects. The DaughterBoard was developed with this in mind and has undergone several radiation tests during its development to verify reliability and fault tolerance.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2024. p. 40
Keywords
CERN, ATLAS, Tile calorimeter, TileCal, FPGA, SEU, TMR, Kintex, Demonstrator, DaughterBoard, Radiation testing, Radiation tolerant
National Category
Accelerator Physics and Instrumentation Physical Sciences
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-228551 (URN)
Presentation
2024-05-13, C4:3031, Roslagstullsbacken 21, 114 21, Stockholm, 13:00
Opponent
Supervisors
Projects
CERN
Funder
CERN
Available from: 2024-04-22 Created: 2024-04-22 Last updated: 2024-04-22Bibliographically approved
Abulaiti, Y., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., Clement, C., . . . Wallängen, V. (2019). Search for light resonances decaying to boosted quark pairs and produced in association with a photon or a jet in proton-proton collisions at root s=13 TeV with the ATLAS detector. Physics Letters B, 788, 316-335
Open this publication in new window or tab >>Search for light resonances decaying to boosted quark pairs and produced in association with a photon or a jet in proton-proton collisions at root s=13 TeV with the ATLAS detector
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2019 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 788, p. 316-335Article in journal (Refereed) Published
Abstract [en]

This Letter presents a search for new light resonances decaying to pairs of quarks and produced in association with a high-p(T) photon or jet. The dataset consists of proton-proton collisions with an integrated luminosity of 36.1 fb(-1) at a centre-of-mass energy of root s = 13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Resonance candidates are identified as massive large-radius jets with substructure consistent with a particle decaying into a quark pair. The mass spectrum of the candidates is examined for local excesses above background. No evidence of a new resonance is observed in the data, which are used to exclude the production of a lepto-phobic axial-vector Z' boson.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-165672 (URN)10.1016/j.physletb.2018.09.062 (DOI)000455364400042 ()
Available from: 2019-02-06 Created: 2019-02-06 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., . . . Wallängen, V. (2018). A search for pair-produced resonances in four-jet final states at root s=13 TeV with the ATLAS detector. European Physical Journal C, 78(3), Article ID 250.
Open this publication in new window or tab >>A search for pair-produced resonances in four-jet final states at root s=13 TeV with the ATLAS detector
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2018 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, no 3, article id 250Article in journal (Refereed) Published
Abstract [en]

A search for massive coloured resonances which are pair-produced and decay into two jets is presented. The analysis uses 36.7 fb(-1) of root s = 13 TeV pp collision data recorded by the ATLAS experiment at the LHC in 2015 and 2016. No significant deviation from the background prediction is observed. Results are interpreted in a SUSY simplified model where the lightest supersymmetric particle is the top squark, (t) over tilde, which decays promptly into two quarks through R-parity-violating couplings. Top squarks with masses in the range 100 GeV < m((T) over tilde) < 410 GeV are excluded at 95% confidence level. If the decay is into a b-quark and a light quark, a dedicated selection requiring two b-tags is used to exclude masses in the ranges 100 GeV < m((t) over tilde) < 470 GeV and 480 GeV < m(<(t)over tilde>) < 610 GeV. Additional limits are set on the pair-production of massive colour-octet resonances.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-156093 (URN)10.1140/epjc/s10052-018-5693-4 (DOI)000428180600005 ()
Available from: 2018-05-14 Created: 2018-05-14 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., . . . Wallängen, V. (2018). A search for resonances decaying into a Higgs boson and a new particle X in the XH -> qqbb final state with the ATLAS detector. Physics Letters B, 779, 24-45
Open this publication in new window or tab >>A search for resonances decaying into a Higgs boson and a new particle X in the XH -> qqbb final state with the ATLAS detector
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 779, p. 24-45Article in journal (Refereed) Published
Abstract [en]

A search for heavy resonances decaying into a Higgs boson (H) and a new particle (X) is reported, utilizing 36.1 fb(-1) of proton-proton collision data at root s = 13 TeV collected during 2015 and 2016 with the ATLAS detector at the CERN Large Hadron Collider. The particle Xis assumed to decay to a pair of light quarks, and the fully hadronic final state XH -> q (q) over bar 'b (b) over bar is analysed. The search considers the regime of high XH resonance masses, where the X and H bosons are both highly Lorentz-boosted and are each reconstructed using a single jet with large radius parameter. A two-dimensional phase space of XH mass versus X mass is scanned for evidence of a signal, over a range of XH resonance mass values between 1 TeV and 4 TeV, and for X particles with masses from 50 GeV to 1000 GeV. All search results are consistent with the expectations for the background due to Standard Model processes, and 95% CL upper limits are set, as a function of XH and X masses, on the production cross-section of the XH -> q (q) over bar 'b (b) over bar resonance.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-156739 (URN)10.1016/j.physletb.2018.01.042 (DOI)000429098900004 ()
Available from: 2018-06-18 Created: 2018-06-18 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bendtz, K., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., . . . Wallängen, V. (2018). Angular analysis of B-d(0) -> K* mu(+)mu(-) decays in pp collisions at root s=8 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (10), Article ID 047.
Open this publication in new window or tab >>Angular analysis of B-d(0) -> K* mu(+)mu(-) decays in pp collisions at root s=8 TeV with the ATLAS detector
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2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 10, article id 047Article in journal (Refereed) Published
Abstract [en]

An angular analysis of the decay B-d(0) -> K*mu(+)mu(-) is presented, based on proton-proton collision data recorded by the ATLAS experiment at the LHC. The study is using 20.3 fb(-1) of integrated luminosity collected during 2012 at centre-of-mass energy of root s = 8TeV. Measurements of the K* longitudinal polarisation fraction and a set of angular parameters obtained for this decay are presented. The results are compatible with the Standard Model predictions.

Keywords
Hadron-Hadron scattering (experiments)
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-161981 (URN)10.1007/JHEP10(2018)047 (DOI)000447258900001 ()
Available from: 2018-11-20 Created: 2018-11-20 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., . . . Wallängen, V. (2018). Measurement of differential cross sections and W+/W- cross-section ratios for W boson production in association with jets at root s=8 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (5), Article ID 077.
Open this publication in new window or tab >>Measurement of differential cross sections and W+/W- cross-section ratios for W boson production in association with jets at root s=8 TeV with the ATLAS detector
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2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 077Article in journal (Refereed) Published
Abstract [en]

This paper presents a measurement of the W boson production cross section and the W+/W- cross-section ratio, both in association with jets, in proton-proton collisions at root s = 8 TeV with the ATLAS experiment at the Large Hadron Collider. The measurement is performed in final states containing one electron and missing transverse momentum using data corresponding to an integrated luminosity of 20.2 fb(-1). Differential cross sections for events with at least one or two jets are presented for a range of observables, including jet transverse momenta and rapidities, the scalar sum of transverse momenta of the visible particles and the missing transverse momentum in the event, and the transverse momentum of the W boson. For a subset of the observables, the differential cross sections of positively and negatively charged W bosons are measured separately. In the cross-section ratio of W+/W- the dominant systematic uncertainties cancel out, improving the measurement precision by up to a factor of nine. The observables and ratios selected for this paper provide valuable input for the up quark, down quark, and gluon parton distribution functions of the proton.

Keywords
Hadron-Hadron scattering (experiments)
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-157774 (URN)10.1007/JHEP05(2018)077 (DOI)000432561800001 ()
Available from: 2018-06-25 Created: 2018-06-25 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., . . . Wallängen, V. (2018). Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at root s=8 TeV using the ATLAS detector. Physics Letters B, 776, 295-317
Open this publication in new window or tab >>Measurement of differential cross sections of isolated-photon plus heavy-flavour jet production in pp collisions at root s=8 TeV using the ATLAS detector
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2018 (English)In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 776, p. 295-317Article in journal (Refereed) Published
Abstract [en]

This Letter presents the measurement of differential cross sections of isolated prompt photons produced in association with a b-jet or a c-jet. These final states provide sensitivity to the heavy-flavour content of the proton and aspects related to the modelling of heavy-flavour quarks in perturbative QCD. The measurement uses proton-proton collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the LHC in 2012 corresponding to an integrated luminosity of up to 20.2 fb(-1). The differential cross sections are measured for each jet flavour with respect to the transverse energy of the leading photon in two photon pseudorapidity regions: vertical bar eta(gamma)vertical bar < 1.37 and 1.56 < vertical bar eta(gamma)vertical bar < 2.37. The measurement covers photon transverse energies 25 < E-T(gamma) < 400 GeV and 25 < E-T(gamma) < 350 GeV respectively for the two vertical bar eta(gamma)vertical bar regions. For each jet flavour, the ratio of the cross sections in the two vertical bar eta(gamma)vertical bar regions is also measured. The measurement is corrected for detector effects and compared to leading-order and next-to-leading-order perturbative QCD calculations, based on various treatments and assumptions about the heavy-flavour content of the proton. Overall, the predictions agree well with the measurement, but some deviations are observed at high photon transverse energies. The total uncertainty in the measurement ranges between 13% and 66%, while the central gamma+b measurement exhibits the smallest uncertainty, ranging from 13% to 27%, which is comparable to the precision of the theoretical predictions.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-153827 (URN)10.1016/j.physletb.2017.11.054 (DOI)000419641100043 ()
Available from: 2018-03-09 Created: 2018-03-09 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., . . . Wallängen, V. (2018). Measurement of differential cross-sections of a single top quark produced in association with a W boson at root s=13TeV with ATLAS. European Physical Journal C, 78(3), Article ID 186.
Open this publication in new window or tab >>Measurement of differential cross-sections of a single top quark produced in association with a W boson at root s=13TeV with ATLAS
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2018 (English)In: European Physical Journal C, ISSN 1434-6044, E-ISSN 1434-6052, Vol. 78, no 3, article id 186Article in journal (Refereed) Published
Abstract [en]

The differential cross-section for the production of a W boson in association with a top quark is measured for several particle-level observables. The measurements are performed using 36.1 fb(-1) of pp collision data collected with the ATLAS detector at the LHC in 2015 and 2016. Differential cross-sections are measured in a fiducial phase space defined by the presence of two charged leptons and exactly one jet matched to a b-hadron, and are normalised with the fiducial cross-section. Results are found to be in good agreement with predictions from several Monte Carlo event generators.

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-154633 (URN)10.1140/epjc/s10052-018-5649-8 (DOI)000426840100001 ()
Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., . . . Wallängen, V. (2018). Measurement of dijet azimuthal decorrelations in pp collisions at root s=8 TeV with the ATLAS detector and determination of the strong coupling. Physical Review D: covering particles, fields, gravitation, and cosmology, 98(9), Article ID 092004.
Open this publication in new window or tab >>Measurement of dijet azimuthal decorrelations in pp collisions at root s=8 TeV with the ATLAS detector and determination of the strong coupling
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2018 (English)In: Physical Review D: covering particles, fields, gravitation, and cosmology, ISSN 2470-0010, E-ISSN 2470-0029, Vol. 98, no 9, article id 092004Article in journal (Refereed) Published
Abstract [en]

A measurement of the rapidity and transverse momentum dependence of dijet azimuthal decorrelations is presented, using the quantity R-Delta phi. The quantity R-Delta phi specifies the fraction of the inclusive dijet events in which the azimuthal opening angle of the two jets with the highest transverse momenta is less than a given value of the parameter Delta phi(max). The quantity R-Delta phi is measured in proton-proton collisions at root s = 8 TeV as a function of the dijet rapidity interval, the event total scalar transverse momentum, and Delta phi(max). The measurement uses an event sample corresponding to an integrated luminosity of 20.2 fb(-1) collected with the ATLAS detector at the CERN Large Hadron Collider. Predictions of a perturbative QCD calculation at next-to-leading order in the strong coupling with corrections for nonperturbative effects are compared to the data. The theoretical predictions describe the data in the whole kinematic region. The data are used to determine the strong coupling alpha(S) and to study its running for momentum transfers from 260 GeV to above 1.6 TeV. Analysis that combines data at all momentum transfers results in alpha(S) (m(Z)) = 0.1127(- 0.0027) (+0.0063).

National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-162862 (URN)10.1103/PhysRevD.98.092004 (DOI)000449397700001 ()
Available from: 2018-12-28 Created: 2018-12-28 Last updated: 2022-03-23Bibliographically approved
Abulaiti, Y., Åkerstedt, H., Bertoli, G., Bessidskaia Bylund, O., Bohm, C., Carney, R. M. D., . . . Wallängen, V. (2018). Measurement of inclusive jet and dijet cross-sections in proton-proton collisions at root s=13 TeV with the ATLAS detector. Journal of High Energy Physics (JHEP) (5), Article ID 195.
Open this publication in new window or tab >>Measurement of inclusive jet and dijet cross-sections in proton-proton collisions at root s=13 TeV with the ATLAS detector
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2018 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 5, article id 195Article in journal (Refereed) Published
Abstract [en]

Inclusive jet and dijet cross-sections are measured in proton-proton collisions at a centre-of-mass energy of 13 TeV. The measurement uses a dataset with an integrated luminosity of 3.2 fb(-1) recorded in 2015 with the ATLAS detector at the Large Hadron Collider. Jets are identified using the anti-lit algorithm with a radius parameter value of R = 0.4. The inclusive jet cross-sections are measured double-differentially as a function of the jet transverse momentum, covering the range from 100 GeV to 3.5 TeV, and the absolute jet rapidity up to vertical bar y vertical bar = 3. The double-differential dijet production cross-sections are presented as a function of the dijet mass, covering the range from 300 GeV to 9 TeV, and the half absolute rapidity separation between the two leading jets within vertical bar y vertical bar < 3, y*, up to y* = 3. Next-to-leading-order, and next-to-next-to-leading-order for the inclusive jet measurement, perturbative QCD calculations corrected for non-perturbative and electroweak effects are compared to the measured cross-sections.

Keywords
Hadron-Hadron scattering (experiments)
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-157716 (URN)10.1007/JHEP05(2018)195 (DOI)000433979200001 ()
Available from: 2018-08-01 Created: 2018-08-01 Last updated: 2022-03-23Bibliographically approved
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