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  • 851. Aharrouche, M.
    et al.
    Colas, J.
    Di Ciaccio, L.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Tayalati, Yahya
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Study of the response of ATLAS electromagnetic liquid argon calorimeters to muons2009Inngår 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, nr 3, s. 419-431Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The response of the ATLAS electromagnetic calorimeter to muons has been studied in this paper. Results on signal over noise ratio, assessment of the detector response uniformity, and position resolution are presented. The possibility to study fine details of the structure of the detector through its response to muons is illustrated on a specific example. Finally, the performance obtained on muons in test-beam is used to estimate the detector uniformity and time alignment precision that will be reachable after the commissioning of the ATLAS detector with cosmic rays.

  • 852. Aharrouche, M.
    et al.
    Colas, J.
    Maaroufi, F.
    Cleland, W.
    Lacour, D.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    et, al
    Response uniformity of the ATLAS liquid argon electromagnetic calorimeter2007Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 582, nr 2, s. 429-455Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction of the ATLAS electromagnetic liquid argon calorimeter modules is completed and all the modules are assembled and inserted in the cryostats. During the production period four barrel and three endcap modules were exposed to test beams in order to assess their performance, ascertain the production quality and reproducibility, and to scrutinize the complete energy reconstruction chain from the readout and calibration electronics to the signal and energy reconstruction. It was also possible to check the full Monte Carlo simulation of the calorimeter. The analysis of the uniformity, resolution and extraction of constant term is presented. Typical non-uniformities of 5 parts per thousand and typical global constant terms of 6 parts per thousand are measured for the barrel and endcap modules.

  • 853. Akhmadaliev, S.
    et al.
    Albiol, F.
    Amaral, P.
    Berglund, S.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Lundquist, J.
    Sellden, B.
    Soderqvist, J.
    Zolnierowski, Y. P.
    et al,
    Results from a new combined test of an electromagnetic liquid argon calorimeter with a hadronic scintillating-tile calorimeter2000Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 449, nr 3, s. 461-477Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new combined test of an electromagnetic liquid argon accordion calorimeter and a hadronic scintillating-tile calorimeter was carried out at the CERN SPS. These devices are prototypes of the barrel calorimeter of the future ATLAS experiment at the LHC. The energy resolution of pions in the energy range from 10 to 300 GeV at an incident angle a of about 12 degrees is well described by the expression sigma/E = ((41.9 +/- 1.6)%/root E + (1.8 +/- 0.1)%)circle plus(1.8 +/- 0.1)/E, where E is in GeV. The response to electrons and muons was evaluated. Shower profiles, shower leakage and the angular resolution of hadronic showers were also studied. Results are compared with those from the previous beam test.

  • 854. Akhmadaliev, S.
    et al.
    Amaral, P.
    Ambrosini, G.
    Amorim, A.
    Anderson, K.
    Johansson, E.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Soderqvist, J.
    Zolnierowski, Y. P.
    et al,
    Hadron energy reconstruction for the ATLAS calorimetry in the framework of the non-parametrical method2002Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 480, nr 03-feb, s. 508-523Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known e/h ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within +/-1% of the true values and the fractional energy resolution is [(58+/-3)%/rootE+(2.5+/-0.3)%]circle plus(1.7+/-0.2)/E. The value of the e/h ratio obtained for the electromagnetic compartment of the combined calorimeter is 1.74+/-0.04 and agrees with the prediction that e/h > 1.66 for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.

  • 855. Andrieux, M. L.
    et al.
    Belhorma, B.
    Belymam, A.
    Benchekroun, D.
    Cherkaoui, R.
    Clement, C.
    Collot, J.
    de Saintignon, P.
    Driouichi, C.
    Dzahini, D.
    El Mouahhidi, Y.
    Erridi, H.
    Ferrari, A.
    Ghazlane, H.
    Hostachy, J. Y.
    Hoummada, A.
    Idrissi, A.
    Laborie, G.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Martin, P.
    Muraz, J. F.
    Soderqvist, J.
    Construction and test of the first two sectors of the ATLAS barrel liquid argon presampler2002Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 479, nr 03-feb, s. 316-333Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The electromagnetic (e.m.) calorimeter of the ATLAS experiment for the Large Hadron Collider will be a sampling liquid argon accordion calorimeter. To achieve sufficient energy resolution, it is necessary to correct for the energy loss in the material upstream of the calorimeter. For this purpose, a separate presampler detector fixed on the inner face of the e.m. calorimeter, in the same cryostat, is being built by the ATLAS collaboration. Two presampler sectors have already been built and tested in their final version. The geometry of the detector and the various steps of its construction are reviewed. The hardware performance of the detector measured both at CERN and at the ISN-Grenoble (specific test bench) is discussed. It is concluded that the presampler will adequately fulfill its role for future operation at the CERN Large Hadron Collider.

  • 856. Angerami, A
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Measurements of photo-nuclear jet production in Pb plus Pb collisions with ATLAS2017Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 967, s. 277-280Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ultra-peripheral heavy ion collisions provide a unique opportunity to study the parton distributions in the colliding nuclei via the measurement of photo-nuclear jet production. An analysis of jet production in ultra-peripheral Pb+Pb collisions at root S-NN = 5.02 TeV performed using data collected with the ATLAS detector in 2015 is described. The data set corresponds to a total Pb+Pb integrated luminosity of 0.38 nb(-1). The ultra-peripheral collisions are selected using a combination of forward neutron and rapidity gap requirements. The cross-sections, not unfolded for detector response, are compared to results from PYTHIA Monte Carlo simulations re-weighted to match a photon spectrum obtained from the STARLIGHT model. Qualitative agreement between data and these simulations is observed over a broad kinematic range suggesting that using these collisions to measure nuclear parton distributions is experimentally realisable.

  • 857. ATLAS Collaboration,
    et al.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    et al.,
    Measurement of exclusive γγ→ℓ+ℓ- production in proton-proton collisions at √s=7 TeV with the ATLAS detector2015Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 749, s. 242-261Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This Letter reports a measurement of the exclusive γγ→ℓ+ℓ- (ℓ=e, μ) cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV by the ATLAS experiment at the LHC, based on an integrated luminosity of 4.6 fb-1. For the electron or muon pairs satisfying exclusive selection criteria, a fit to the dilepton acoplanarity distribution is used to extract the fiducial cross-sections. The cross-section in the electron channel is determined to be σγγ→e+e-excl.=0.428 ± 0.035 (stat.) ± 0.018 (syst.) pb for a phase-space region with invariant mass of the electron pairs greater than 24 GeV, in which both electrons have transverse momentum pT>12 GeV and pseudorapidity |η|<2.4. For muon pairs with invariant mass greater than 20 GeV, muon transverse momentum pT>10 GeV and pseudorapidity |η|<2.4, the cross-section is determined to be σγγ→μ+μ-excl.=0.628 ± 0.032 (stat.) ± 0.021 (syst.) pb. When proton absorptive effects due to the finite size of the proton are taken into account in the theory calculation, the measured cross-sections are found to be consistent with the theory prediction.

  • 858. Aubert, B.
    et al.
    Ballansat, J.
    Bazan, A.
    Beaugiraud, B.
    Cros, P.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Lundqvist, J.
    Pearce, Mark
    KTH, Tidigare Institutioner                               , Fysik.
    Rydstrom, S.
    et al,
    Performance of the ATLAS electromagnetic calorimeter end-cap module 02003Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 500, nr 03-jan, s. 178-201Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction and beam test results of the ATLAS electromagnetic end-cap calorimeter pre-production module 0 are presented. The stochastic term of the energy resolution is between 10% and 12.5% GeV1/2 over the full pseudorapidity range. Position and angular resolutions are found to be in agreement with simulation. A global constant term of 0.6% is obtained in the pseudorapidity range 2.5 < η < 3.2 (inner wheel).

  • 859. Aubert, B.
    et al.
    Ballansat, J.
    Bazan, A.
    Beaugiraud, B.
    Lund-Jensen, Bengt.
    KTH, Tidigare Institutioner (före 2005), Fysik.
    Lundqvist, J.
    Pearce, Mark
    KTH, Tidigare Institutioner (före 2005), Fysik.
    Rydstrom, S.
    et al,
    Performance of the ATLAS electromagnetic calorimeter barrel module 02003Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 500, nr 03-jan, s. 202-231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction and performance of the barrel pre-series module 0 of the future ATLAS electromagnetic calorimeter at the LHC is described. The signal reconstruction and performance of ATLAS-like electronics has been studied. The signal to noise ratio for muons has been found to be 7.11 +/- 0.07. An energy resolution of better than 9.5% GeV1/2 / rootE (sampling term) has been obtained with electron beams of up to 245 GeV. The uniformity of the response to electrons in an area of Deltaeta x Deltaphi = 1.2 x 0.075 has been measured to be better than 0.8%.

  • 860. Aubert, B.
    et al.
    Beaugiraud, B.
    Colas, J.
    Delebecque, P.
    Di Ciaccio, L.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Rydstrom, S.
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Construction, assembly and tests of the ATLAS electromagnetic barrel calorimeter2006Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 558, nr 2, s. 388-418Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    The construction and assembly of the two half barrels of the ATLAS central electromagnetic calorimeter and their insertion into the barrel cryostat are described. The results of the qualification tests of the calorimeter before installation in the LHC ATLAS pit are given.

  • 861. Aubert, B.
    et al.
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Lundqvist, J.
    KTH.
    Megner, L.
    KTH.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Rydström, S
    KTH.
    Steffens, J.
    et al.,
    Erratum to “Performance of the ATLAS electromagnetic calorimeter barrel module 0” [Nucl. Instr. and Meth. A 500 (2003) 202–231]2004Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 517, nr 1-3, s. 399-402Artikkel i tidsskrift (Fagfellevurdert)
  • 862.
    Balek, Petr
    et al.
    Weizmann Inst Sci, Fac Phys, Dept Particle Phys & Astrophys, 234 Herzl St, IL-76100 Rehovot, Israel..
    Balek, P.
    Weizmann Inst Sci, Dept Particle Phys, Rehovot, Israel..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Charged-hadron suppression in Pb plus Pb and Xe plus Xe collisions measured with the ATLAS detector2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 571-574Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ATLAS detector at the LHC recorded 0.49 nb(-1) of Pb+Pb collisions and 25 of pp(-1) collisions, both at the center-of-mass energy 5.02 TeV per nucleon pair. Recently, ATLAS also recorded 30 mu b(-1) of Xe+Xe collisions at the center-of-mass energy 5.44 TeV, which provides a new opportunity to study the system-size dependence of the charged-hadron production in heavy-ion collisions. The large acceptance of the ATLAS detector allows to measure the spectra of charged hadrons in a wide range of pseudorapidity and transverse momentum. The nuclear modification factors R-AA are constructed as a ratio of the spectra measured in Pb+Pb or Xe+Xe collisions to that measured in pp collisions. The R-AA obtained in the two systems are presented for different centrality intervals and the results are discussed.

  • 863.
    Bold, Tomasz
    et al.
    AGH Univ Sci & Technol, Krakow, Poland..
    Bold, T.
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Krakow, Poland..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Measurement of the azimuthal anisotropy of charged particles in 5.02 TeV Pb+Pb and 5.44 TeV Xe+Xe collisions with ATLAS2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 391-394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The data collected by the ATLAS experiment during the 2015 Pb+Pb and 2017 Xe+Xe LHC runs offer new opportunities to study charged particle azimuthal anisotropy. The high-statistics Pb+Pb sample allows for a detailed study of the azimuthal anisotropy of produced particles. This should improve the understanding of initial conditions of nuclear collisions, hydrodynamical behavior of quark-gluon plasma and parton energy loss. New ATLAS measurements of differential and global Fourier harmonics of charged particles (v(n)) in 5.02 TeV Pb+Pb and 5.44 TeV Xe+Xe collisions in a wide range of transverse momenta, pseudorapidity (vertical bar eta vertical bar < 2.5) and collision centrality are presented. The higher order harmonics, sensitive to fluctuations in the initial state, are measured up to n = 7 using the two-particle correlation, cumulant and scalar product methods. The dynamic properties of QGP are studied using a recently-proposed modified Pearson's correlation coefficient, rho(v(n)(2), p(T)), between the event-wise mean transverse momentum and the magnitude of the flow vector in 5.02 TeV Pb+Pb and p+Pb collisions. Several important observations are made. The elliptic and triangular flow harmonics show an interesting universal p(T)-scaling. A linear correlation between the v(2) and v(3) coefficients at low and high p(T) ranges is observed and quantified. The correlation coefficient for v(2) is found to be negative in peripheral and positive in central Pb+Pb collisions. The value for v(3) is found to be much smaller than for v(2) and have similar centrality behavior as the v(2).

  • 864. Buchanan, N. J.
    et al.
    Chen, L.
    Gingrich, D. M.
    Liu, S.
    Grahn, K. J.
    Hansson, P.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Chu, M. L.
    et al,
    Radiation qualification of the front-end electronics for the readout of the ATLAS liquid argon calorimeters2008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiation-tolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.

  • 865. Buchanan, N. J.
    et al.
    Chen, L.
    Gingrich, D. M.
    Liu, S.
    Hansson, P.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    et al,
    ATLAS liquid argon calorimeter front end electronics2008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ATLAS detector has been designed for operation at CERN's Large Hadron Collider. ATLAS includes a complex system of liquid argon calorimeters. This paper describes the architecture and implementation of the system of custom front end electronics developed for the readout of the ATLAS liquid argon calorimeters.

  • 866. Carlson, P.
    et al.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Peskov, V.
    Gaseous photomultipliers with solid photocathodes for the detection of sparks, flames and dangerous gases2003Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 505, nr 02-jan, s. 207-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In many applications, it is necessary to detect sparks or flames in daylight conditions or in illuminated areas. Most flames emit strongly in the ultraviolet spectrum (180-280 nm), and this property can be used for reliable identification of flames. We have developed new spark and flame detectors based on gaseous photomultipliers with CsI, CuI or CsTe photocathodes. A modified version of the detector can also detect smoke and dangerous vapors. These detectors are able to perform complex monitoring and detection functions. Some of their advantages are: low cost, high sensitivity, large output signal and operation under battery power. Gaseous photomultipliers can be position sensitive and, if necessary, be used in combination with various optical systems, for example for monitoring flames from space.

  • 867. Carlson, P.
    et al.
    Iacobeaus, C.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Periale, L.
    Peskov, V.
    Rodionov, I.
    Beyond the RICH: innovative photosensitive gaseous detectors for new fields of applications2003Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 502, nr 1, s. 189-194Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed and successfully used several innovative designs of detectors with solid photocathodes. The main advantage of these detectors is that rather high gains (> 10(4)) can be achieved in a single multiplication step. This is possible by, for instance, exploiting the secondary electron multiplication and limiting the energy of the steamers by distributed resistivity. The single step approach also allows a very good position resolution to be achieved in some devices: 50 mum on line without applying any treatment method (like center of gravity). The main focus of our report is new fields of applications for these detectors and the optimization of their designs for such purposes.

  • 868. Charlton, D. G.
    et al.
    Dowell, J. D.
    Homer, R. J.
    Jovanovic, P.
    Kenyon, I. R.
    Mahout, G.
    Shaylor, H. R.
    Wilson, J. A.
    Rudge, A.
    Fopma, J.
    Mandic, I.
    Nickerson, R. B.
    Shield, P.
    Wastie, R.
    Weidberg, A. R.
    Eek, L. O.
    Go, A.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner                               , Fysik.
    Pearce, Mark
    KTH, Tidigare Institutioner                               , Fysik.
    Soderqvist, J.
    Morrissey, M.
    White, D. J.
    System tests of radiation hard optical links for the ATLAS semiconductor tracker2000Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 443, nr 03-feb, s. 430-446Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A prototype optical data and Timing Trigger and Control transmission system based on LEDs and PIN-diodes has been constructed. The system would be suitable in terms of radiation hardness and radiation length for use in the ATLAS SemiConductor Tracker. Bit error rate measurements were performed for the data links and for the links distributing the Timing, Trigger and Control data from the counting room to the front-end modules. The effects of cross-talk between the emitters and receivers were investigated. The advantages of using Vertical Cavity Surface Emitting Lasers (VCSELs) instead of LEDs are discussed.

  • 869.
    Citron, Zvi
    et al.
    Ben Gurion Univ Negev, Beer Sheva, Israel..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Electroweak probes of small and large systems with the ATLAS detector2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 603-606Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Measurements of isolated prompt photon and massive electroweak (W and Z) boson production in different collision systems are of great interest to understand the partonic structure of heavy nuclei, and serve as a constraint on the initial state in larger collision systems. These channels are sensitive to a variety of effects such as the modification of the parton densities in nuclei in certain kinematic regions, and the energy loss of partons as they undergo multiple interactions in the nucleus before the hard parton-parton scattering. High-statistics samples of lead-lead and proton-lead collision data at root s(NN)=5.02 TeV and 8.16 TeV, respectively, taken by the ATLAS experiment at the LHC, as well as proton-proton comparison data at analogous collision energies, allow for a detailed study of these phenomena in data and comprehensive comparisons to the predictions of a variety of theoretical approaches. This paper presents the latest ATLAS results in these topics, including updated results on inclusive prompt photon production in proton-lead collisions over a broad kinematic range and high-precision W boson results in lead lead collisions.

  • 870. Colas, J.
    et al.
    Di Ciaccio, L.
    El Kacimi, M.
    Gaumer, O.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Tayalati, Y.
    et, al
    Lafaye, Remi
    Univ Savoie, LAPP, CNTS IN2P3, Annecy Le Vieux, France.
    Position resolution and particle identification with the ATLAS EM calorimeter2005Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 550, nr 02-jan, s. 96-115Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the years between 2000 and 2002 several pre-series and series modules of the ATLAS EM barrel and end-cap calorimeter were exposed to electron, photon and pion beams. The performance of the calorimeter with respect to its finely segmented first sampling has been studied. The polar angle resolution has been found to be in the range 50-60 (mrad)/root E(GeV). The pi(0) rejection has been measured to be about 3.5 for 90% photon selection efficiency at PT = 50GeV/c. e-pi separation studies have indicated that a pion fake rate of (0.07-0.5)% can be achieved while maintaining 90% electron identification efficiency for energies up to 40 GeV.

  • 871.
    Derendarz, Dominik
    et al.
    PAS, Inst Nucl Phys, Ul Radzikowskiego 152, PL-31342 Krakow, Poland..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Measurement of the flow harmonic correlations in pp, p plus Pb and low multiplicity Pb plus Pb collisions with the ATLAS detector at the LHC2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 479-482Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent measurements of the correlations between flow harmonics obtained using four-particle symmetric cumulants and three-particle asymmetric cumulants with the ATLAS detector at the LHC are described. The data sets of pp, p+Pb and peripheral Pb+Pb collisions at various energies are analyzed, aiming to probe the long-range collective nature of multi-particle production in small systems. The sensitivity of the standard cumulant method to non-flow correlations is investigated by introducing the subevents method. A systematic reduction of non-flow effects is observed when using the two-subevent method. Further reduction is observed with the three-subevent method that is consistent with the results obtained with the four-subevent one. A negative correlation between v(2) and v(3) and a positive correlation between v(2) and v(4), for all studied collision systems and over full multiplicity range, is observed. The correlation strength computed as symmetric cumulants normalized by the < v(n)(2)> is similar for all collision systems and weakly depends on multiplicity. These measurements provide new evidence for long-range multi-particle collectivity in small collision systems and quantify the nature of its event-by-event fluctuations.

  • 872.
    Di Mauro, A.
    et al.
    CERN, PH Div, CH-1211 Geneva 23, Switzerland..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Martinengo, P.
    CERN, PH Div, CH-1211 Geneva 23, Switzerland..
    Nappi, E.
    Univ Bari, Div Phys, I-70126 Bari, Italy.;INFN Bari, I-70126 Bari, Italy..
    Peskov, V.
    CERN, PH Div, CH-1211 Geneva 23, Switzerland.;CERN, DIV PH, CH-1211 Geneva, Switzerland..
    Periale, L.
    INAF, Astroph Dept, I-10025 Turin, Italy..
    Picchi, P.
    Ist Nazl Fis Nucl, I-00044 Frascati, Italy..
    Pietropaolo, F.
    INFN, I-35020 Padua, Italy. Reagent Res Ctr, Moscow 125190, Russia..
    Rodionov, I.
    A New GEM-like Imaging Detector with Electrodes Coated with Resistive Layers2006Inngår i: 2006 IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD, VOL 1-6, IEEE , 2006, s. 3852-3859Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have developed and tested several prototypes of GEM-like detectors with electrodes coated with resistive layers. These detectors can operate stably at gains close to 10(5) and if discharges appear at higher gains the protective layers restrict their energies so that they do not damage either the detector or the readout electronics. We discovered that the cathodes of these detectors could be coated by CsI layers and in such a way the detectors gain high efficiency for the UV photons. We also demonstrated that such detectors can operate stably in the cascade mode and high overall gains (similar to 10(6)) are reachable. This opens applications in several areas, for example in RICH or in noble liquid TPCs. The simplified prototype of the RICH detector was built and successfully tested in the laboratory. The first results of operation of the new detectors at cryogenic temperatures are given.

  • 873. Di Mauro, A.
    et al.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Martinengo, P.
    Nappi, E.
    Oliveira, R.
    Peskov, V.
    Periale, L.
    Picchi, P.
    Pietropaolo, F.
    Rodionov, I.
    Santiard, J. C.
    Development of innovative micro-pattern gaseous detectors with resistive electrodes and first results of their applications2007Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 581, nr 1-2, s. 225-231Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The paper summarizes our latest progress in the development of newly introduced micro-pattern gaseous detectors with resistive electrodes. These resistive electrodes protect the detector and the front-end electronics in case of occasional discharges and thus make the detectors very robust and reliable in operation. As an example, we describe in greater detail a recently developed GEM-like detector, fully spark-protected with electrodes made of resistive kapton. We discovered that all resistive layers used in these studies (including kapton) that are coated with photosensitive layers, such as CsI, can be used as efficient photocathodes for detectors operating in a pulse counting mode. There is a description of the first applications of such detectors combined with CsI or SbCs photocathodes for the detection of UV photons at room and cryogenic temperatures.

  • 874. Ersmark, T.
    et al.
    Carlson, P.
    Daly, E.
    Fuglesang, C.
    Gudowska, I.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Nieminen, P.
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Santin, G.
    Influence of geometry model approximations on Geant4 simulation results of the Columbus/ISS radiation environment2007Inngår i: Radiation Measurements, ISSN 1350-4487, E-ISSN 1879-0925, Vol. 42, nr 8, s. 1342-1350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of geometry model approximations on Geant4 Monte Carlo simulation results of the radiation environment on-board the Columbus module of the International Space Station (ISS) has been investigated. Three geometry models of Columbus with different levels of detail and a geometry model of ISS have been developed. These geometries have been used for Geant4 simulations of the radiation environment inside Columbus induced by trapped protons and Galactic Cosmic Ray protons. Simulated dose rates and particle spectra on-board Columbus for each of the three Columbus models, with or without the ISS geometry model included, are presented and compared. From comparisons of simulated dose rates and particle spectra for the three different geometry models it was found that the most detailed geometry model (750 volumes) produced results similar to a much less detailed model (23 volumes). The most detailed geometry model was concluded to be a sufficiently detailed approximation of the physical Columbus for the purpose of proton induced space radiation studies. The simulated dose rates are compatible with measurements on-board the ISS. The simulation results also show that an increase in shielding thickness decreases the simulated dose rate induced by trapped protons. For Galactic Cosmic Ray protons the dose rate remains unchanged or is slightly increased.

  • 875.
    Ersmark, Tore
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Carlson, Per
    KTH, Tidigare Institutioner, Fysik.
    Daly, E
    Fuglesang, C
    Gudowska, I
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    Nartallo, R
    Nieminen, P
    Pearce, Mark
    KTH, Tidigare Institutioner, Fysik.
    Santin, G
    Sobolevsky, N
    Status of the DESIRE project: Geant4 physics validation studies and first results from columbus/ISS radiation simulations2004Inngår i: IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, 2004, s. 1540-1544Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The DESIRE (Dose Estimation by Simulation of the ISS Radiation Environment) project aimes to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Firstly physics benchmark studies have been performed and comparisons made to experimental data and other particle transport programs. This will be followed by a detailed evaluation of the incident radiation fields on the ISS and culminate with the geometry modelling and full-scale flux and dose simulations for the Columbus. Geant4 validation studies are presented here. These concern the angle and energy distribution of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data and other particle transport programs. Geant4 using the "Binary Cascade" model for inelastic nucleon reactions performs very well in these comparisons but some issues with other models remain to be resolved if these models are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of relevant radiation field components through the hull of the Columbus/ISS are also presented.

  • 876.
    Ersmark, Tore
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Carlson, Per
    KTH, Tidigare Institutioner, Fysik.
    Daly, E.
    Fuglesang, C.
    Gudowska, I.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    Nartallo, R.
    Nieminen, P.
    Pearce, Mark
    KTH, Tidigare Institutioner, Fysik.
    Santin, G.
    Sobolevsky, N.
    Status of the DESIRE project: Geant4 physics validation studies and first results from columbus/ISS radiation simulations2004Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 51, nr 4, s. 1378-1384Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Dose Estimation by Simulation of the ISS Radiation Environment (DESIRE) project aims to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Since Geant4 has not been previously used for this type of application it needs to be validated. This will be followed by a detailed evaluation of the incident radiation fields on ISS and culminate with the geometry modeling and full-scale flux and dose simulations for Columbus. Geant4 validation studies and comparisons to other tools are presented. These concern the angle and energy distributions of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data, and other particle transport programs. Geant4 using the Binary Cascade model for inelastic nucleon reactions performs very well in these comparisons, but some issues with other models remain to be resolved if they are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of some relevant radiation field components through the hull of a simplified model of Columbus are also presented.

  • 877. Ersmark, Tore
    et al.
    Carlson, Per
    Daly, Eamonn
    Fuglesang, Christer
    Gudowska, Irena
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Nieminen, Petteri
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Santin, Giovanni
    Geant4 Monte Carlo simulations of the galactic cosmic ray radiation environment on-board the international space station/columbus2007Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 54, nr 5, s. 1854-1862Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A characterization of the Galactic Cosmic Ray (GCR) induced radiation environment on-board Columbus and the Inter-national Space Station (ISS) has been carried out using the Geant4 Monte Carlo particle transport toolkit and detailed geometry models of Columbus and ISS. Dose and dose equivalent rates, as well as penetrating particle spectra are presented. Simulation results indicate that the major part of the dose rates due to GCR protons are associated with secondary particles produced in the hull of ISS. Neutrons contribute about 15% of the GCR proton dose equivalent rate and mesons about 10%. More than 40% of the simulated GCR proton dose and dose equivalent rates are due to protons in the energy range above 10 GeV. Protons in the energy range above 50 GeV contribute only 5% to the dose rates. The total simulated dose and dose equivalent rates at solar maximum are 63 mu Gy/d and 123 mu Sv/d, respectively. The dose equivalent rate underestimates measurements made during the 2001 solar maximum. The discrepancy can be attributed to deficiencies in hadronic ion-nuclei interaction models for heavy ions and to the lack of such models above 10 GeV/N in Geant4.

  • 878. Ersmark, Tore
    et al.
    Carlson, Per
    Daly, Earnorm
    Fuglesang, Christer
    Gudowska, Irena
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Nierninen, Petteri
    Pearce, Mark
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Santin, Giovanni
    Geant4 Monte Carlo Simulations of the belt proton radiation environment on board the international space Station/Columbus2007Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 54, nr 4, s. 1444-1453Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A detailed characterization of the trapped-proton-induced radiation environment on board Columbus and the International Space Station (ISS) has been carried out using the Geant4 Monte Carlo particle transport toolkit. Dose and dose equivalent rates, as well as penetrating particle spectra are presented. These results are based on detailed Geant4 geometry models of Columbus and ISS, comprising a total of about 1000 geometry volumes. Simulated trapped-proton dose rates are found to be strongly dependent on ISS altitude. Dose rates for different locations inside the Columbus cabin are presented, as well as for different models of the incident trapped-proton flux. Dose rates resulting from incident anisotropic trapped protons are found to be lower than, or equal to, those of omnidirectional models. The anisotropy induced by the asymmetric shielding distribution of Columbus/ISS is also studied. The simulated trapped-proton dose (equivalent) rates, averaged over different locations inside Columbus, are 120 mu Gy/d (154 mu Sv/d) and 79 mu Gy/d (102 mu Sv/d) for solar minimum and maximum conditions according to AP8 incident proton spectra and an ISS orbit of 380 km. The solar maximum dose rates are found to be of the same order as measurements in other modules in the present ISS.

  • 879.
    Fuglesang, Christer
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Larsson, Oscar
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Benghin, V. V.
    Casolino, M.
    Chernikch, I. V.
    di Fino, L.
    Larosa, M.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Narici, L.
    Nikolaev, I. V.
    Petrov, V. M.
    Picozza, P.
    de Santis, C.
    Zaconte, V.
    Relative nuclear abundances, LET and dose rates at various locations and configurations in ISS from the ALTCRISS experiment2013Inngår i: 64th International Astronautical Congress: Radiation Fields, Effects and Risks in Human Space Missions, 2013Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Over the years many devices, using different technologies and various locations, have been used - and are still in use - on the International Space Station, ISS, to measure and map the radiation and cosmic particle flux which astronauts as well as sensitive electronics are exposed to. This presentation presents recent analyses and results from the SilEye-3/Alteino detector during the ESA-sponsored project ALTCRISS. Comparisons are made with data from other experiments, such as ALTEA and PADLES. Alteino is a Si-strip detector, developed from the two SilEye detectors that were operated on Mir, in particular for studies of the Light Flash phenomena. Alteino was used at several locations, and orientations, in the Russian segment of ISS from late 2005 through 2007. Many of the data sets were obtained with a shielding of 5 g/cm2 polyethylene in front of the detector. Data on nuclei from C to Fe in the energy range above ≃  60 MeV/n show an increase in relative abundance for odd Z inside ISS compared to the outside, due to fragmentation in the hull. Fluxes and relative abundances vary with location and shielding, where the material of the station itself plays a major role. The difference in flux can be as much as 50%. LET spectra - which are not restricted to single particle events - show similar tendencies, though when converted to equivalent dose rates the effect of the polyethylene is somewhat pronounced. Comparison with ALTEA data shows slightly higher dose rates for Alteino in the Russian segment, which can be expected due to that ALTEA operated in the US lab Destiny with more station material around it. As expected, the response of CR39 in terms of equivalent dose rate is higher than Alteino, due to the smaller acceptance energy range of the latter.

  • 880. G., Aad
    et al.
    Jovicevic, J.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Kuwertz, E. S.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Morley, A. K.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et.al, .
    Search for new phenomena in events with three or more charged leptons in pp collisions at √s=8 TeV with the ATLASdetector2015Inngår i: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, Vol. 2015, nr 8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A generic search for anomalous production of events with at least three charged leptons is presented. The data sample consists of pp collisions at s=8" role="presentation" style="box-sizing: border-box; display: inline-table; line-height: normal; letter-spacing: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">s√=8s=8 TeV collected in 2012 by the ATLAS experiment at the CERN Large Hadron Collider, and corresponds to an integrated luminosity of 20.3 fb−1. Events are required to have at least three selected lepton candidates, at least two of which must be electrons or muons, while the third may be a hadronically decaying tau. Selected events are categorized based on their lepton flavour content and signal regions are constructed using several kinematic variables of interest. No significant deviations from Standard Model predictions are observed. Model-independent upper limits on contributions from beyond the Standard Model phenomena are provided for each signal region, along with prescription to re-interpret the limits for any model. Constraints are also placed on models predicting doubly charged Higgs bosons and excited leptons. For doubly charged Higgs bosons decaying to  or μτ, lower limits on the mass are set at 400 GeV at 95% confidence level. For excited leptons, constraints are provided as functions of both the mass of the excited state and the compositeness scale Λ, with the strongest mass constraints arising in regions where the mass equals Λ. In such scenarios, lower mass limits are set at 3.0 TeV for excited electrons and muons, 2.5 TeV for excited taus, and 1.6 TeV for every excited-neutrino flavour.

  • 881.
    Grabowska-Bold, Iwona
    et al.
    AGH Univ Sci & Technol, Krakow, Poland..
    Grabowska-Bold, I
    AGH Univ Sci & Technol, Fac Phys & Appl Comp Sci, Krakow, Poland..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Highlights from the ATLAS experiment2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 8-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This report provides an overview of the new results obtained by the ATLAS Collaboration at the LHC, which were presented at the Quark Matter 2018 conference. These measurements were covered in 12 parallel talks, one flash talk and 11 posters. In this document, a discussion of results is grouped into four areas: electromagnetic interactions, jet quenching, quarkonia and heavy-flavour production, and collectivity in small and larger systems. Measurements from the xenon-xenon collisions based on a short run collected in October 2017 are reported for the first time.

  • 882.
    Hu, Qipeng
    et al.
    Brookhaven Natl Lab, Upton, NY 11973 USA..
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Measurement of heavy flavor production and azimuthal anisotropy in small and large systems with ATLAS2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 687-690Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Heavy-flavor hadron production and collective motion in A+A collisions provide insight into the energy loss mechanism and transport properties of heavy quarks in the QGP. The same measurements in p+A collisions serve as an important baseline for understanding the observations in A+A collisions. For example, detailed studies of heavy-flavor hadron azimuthal anisotropy in p+A collisions may help to address whether the observed long-range "ridge" correlation arises from hard or semi-hard processes, or if it is the result of mechanisms unrelated to the initial hardness scale. These proceedings summarize heavy-flavor hadron production, via their semi-leptonic decay to muons in 2.76 TeV Pb+Pb and pp collisions, non-prompt J/psi in 5.02 TeV Pb+Pb and pp collisions, and prompt D-0 mesons in 8.16 TeV p+Pb collisions using ATLAS detector at the LHC. Azimuthal anisotropy of heavy-flavor hadrons is studied via their decay muons in 2.76 TeV Pb+Pb and 8.16 TeV p+Pb collisions, and via non-prompt J/psi in 5.02 TeV Pb+Pb collisions. Strong suppression of heavy-flavor hadron production and azimuthal anisotropy are observed in Pb+Pb collisions, while significant azimuthal anisotropy of heavy-flavor muons is observed in p+Pb collisions, without evidence of the modification of their production rates.

  • 883. Iacobaeus, C.
    et al.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ostling, J.
    Pavlopoulos, P.
    Peskov, V.
    Tokanai, F.
    A high position resolution X-ray detector: An Edge on illuminated capillary plate combined with a gas amplification structure2006Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 53, nr 2, s. 554-561Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed and successfully tested a prototype of a new high position resolution hybrid X-ray detector. It contains a thin-wall lead glass capillary plate converter of X-rays combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0-90 degrees. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation was between 5-30% in single step mode and up to 50% in a multi-layered combination. Depending on the capillary's geometry, the position resolution achieved was between 50-250 mu m in digital form and was practically independent of the photon's energy or gas mixture. The usual lead glass capillary plates operated without noticeable charging up effects at counting rates of 50 Hz/mm(2) and hydrogen treated capillaries-up to 10(5) Hz/mm(2). The developed detector has several important potential advantages over the exciting X-ray detectors and may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), as well as many other applications.

  • 884. Iacobaeus, C.
    et al.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    Ostling, J.
    Pavlopoulos, P.
    Peskov, V.
    Tokanai, F.
    An X-ray scanner based on an "edge on" illuminated capillary plate combined with a gas amplification structure2004Inngår i: 2004 IEEE Nuclear Science Symposium Conference Record, 2004, s. 489-492Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have developed and successfully tested a prototype of a new type of high position resolution X-ray scanner. It contains a thin wall lead glass capillary plate converter of X-rays combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0-90°. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation, was between 5-30% in a single step mode and up to 50% in a multi-layered combination. Depending on the capillary's geometry, the position resolution achieved was between 50-250 μm in digital form and was practically independent of the photon's energy or gas mixture. The usual lead glass capillary plates operated without noticeable charging up effects at counting rates of 50 Hz/mm2, and hydrogen treated capillaries up to 10 5 Hz/mm2. Finally, a prototype of the X-ray scanner based on an "edge-on" illumination capillary plate was built and tested. The developed detector open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), crystallography and many other applications.

  • 885. Iacobaeus, C.
    et al.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Peskov, V.
    An X-ray scanner prototype based on a novel hybrid gaseous detector2007Inngår 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 02-jan, s. 61-64Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed a prototype of a new type of hybrid X-ray detector. It contains a thin wall (few mu m) edge-illuminated lead glass capillary plate (acting as a converter of X-rays photons to primary electrons) combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0 degrees to 90 degrees. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation, was between a few and similar to 40%. The position resolution achieved was similar to 50 mu m in digital form and was practically independent of the photon's energy or gas mixture. The developed detector may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), crystallography and many other applications.

  • 886. Jackson, P. D.
    et al.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Search for charged Higgs bosons produced in association with a top quark and decaying via H± → τν using pp collision data recorded at s=13 TeV by the ATLAS detector2016Inngår i: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 759, s. 555-574Artikkel i tidsskrift (Fagfellevurdert)
  • 887. Jia, J Y
    et al.
    Kastanas, Konstatinos A.
    KTH, Skolan för teknikvetenskap (SCI), Fysik.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    et al.,
    Heavy Ion Results from ATLAS2017Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 967, s. 51-58Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    These proceedings provide an overview of the new results obtained with the ATLAS detector at the LHC, which were presented in the Quark Matter 2017 conference. These results were covered by twelve parallel talks, one flash talk and eleven posters. These proceedings group these results into five areas: initial state, jet quenching, quarkonium production, longitudinal flow dynamics, and collectivity in small systems.

  • 888.
    Larsson, Oscar
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Benghin, V. V.
    Berger, T.
    Casolino, M.
    Di Fino, L.
    Fuglesang, Christer
    Larosa, M.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Nagamatsu, A.
    Narici, L.
    Nikolaev, I. V.
    Picozza, P.
    Reitz, G.
    De Santis, C.
    Zaconte, V.
    Measurements of heavy-ion anisotropy and dose rates in the Russian section of the International Space Station with the Sileye-3/Alteino detector2015Inngår i: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 42, nr 2, s. 025002-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work we present data on linear energy transfer (LET), dose and dose equivalent rates from different locations of the Russian part of the International Space Station (ISS) measured by the Sileye-3/Alteino detector. Data were taken as part of the ESA ALTCRISS project from late 2005 through 2007. The LET rate data shows a heavy-ion (LET > 50 keV/mu m) anisotropy. From the heavy-ion LET rate in the Zvezda service module we find ISS (y) over cap (Starboard) and (z) over cap (Nadir) to be about 10-15 times higher than in (x) over cap (Forward). The situation is similar for dose and dose equivalent rates, ranging from 25-40 mu Gy d(-1) in (x) over cap to about 75 mu Gy d(-1) in (z) over cap, whereas for the dose equivalent the rate peaks in (y) over cap with around 470 mu Sv d(-1). The heavy-ion anisotropy confirms what has been reported by the ALTEA collaboration. Measurements using two sets of passive detectors, DLR-TLDs and PADLES (TLD+CR-39), have also been performed in conjunction with Alteino measurements, both shielded and unshielded. The passive detectors register a dose rate about 3-5 times as high as Alteino, 260-280 mu Gy d(-1) for PADLES and 200-260 mu Gy d(-1) for DLR-TLDs. For the dose equivalent PADLES measurements ranges from 560-740 mu Sv d(-1).

  • 889.
    Larsson, Oscar
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Benghin, V. V.
    Casolino, M.
    Chernikch, I. V.
    di Fino, L.
    Fuglesang, Christer
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Larosa, M.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Narici, L.
    Nikolaev, I. V.
    Petrov, V. M.
    Picozza, P.
    de Santis, C.
    Zaconte, V.
    Relative nuclear abundance from C to Fe and integrated flux inside the Russian part of the ISS with the Sileye-3/Alteino experiment2014Inngår i: Journal of Physics G: Nuclear and Particle Physics, ISSN 0954-3899, E-ISSN 1361-6471, Vol. 41, nr 1, s. 015202-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work we present data from the Sileye-3/Alteino detector on board the International Space Station (ISS), which was gathered following a recalibration after several years in orbit. We also measure the relative nuclei abundance and integrated flux, which were normalized to the solar modulation values of August 2007. The measurements were made at different locations of the Russian part of the ISS. The relative nuclear abundances of C to Fe in relation to C, in an energy range above similar or equal to 60 MeV/n, shows high levels of odd Z particles inside the ISS and an under-abundance of C and O compared with the galactic spectrum, as presented by Simpson in 1983. In addition, the values of the integrated flux varies primarily according to location and detector orientation. An additional polyethylene shield also reduces the flux, although in a lower amount than changes in the orientation of the telescope. Data were taken as part of the ESA ALTCRISS project from late 2005 through to 2007.

  • 890.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    The status of the construction and the performance of the ATLAS liquid argon electromagnetic calorimeters2004Inngår i: 2003 IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD, VOLS 1-5 / [ed] Metzler, SD, 2004, s. 41-44Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The construction of the ATLAS liquid argon electromagnetic calorimeters is about to be completed. The barrel calorimeter and the first end cap are inserted in their cryostats. The quality control performed during the production has resulted in only a very small fraction of malfunctioning channels, similar to0.1 parts per thousand., and a low constant term in the energy resolution. Several modules of the calorimeter and their corresponding presampler sectors have been tested in electron beams and their energy resolution has been shown to be within the ATLAS requirements. The local constant term is better than 0.4% for all measured cells and the global constant term which includes the cell to cell response variation is less than 0.7%.

  • 891.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    The status of the construction and the performance of the ATLAS liquid argon electromagnetic calorimeters2004Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 51, nr 5, s. 2181-2186Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The construction of the ATLAS liquid argon electromagnetic calorimeters is about to be completed. The barrel calorimeter and the first end-cap are inserted in their cryostats. The quality control performed during the production has resulted in only a very small fraction of malfunctioning channels (similar to0.1%) and a low constant term in the energy resolution. Several modules of the calorimeter and their corresponding presampler sectors have been tested in electron beams, and their energy resolution has been shown to be within the ATLAS requirements. The local constant term is better than 0.4% for all measured cells and the global constant term which includes the cell-to-cell response variation is less than 0.7%.

  • 892.
    Perepelitsa, Dennis, V
    et al.
    Univ Colorado, Boulder, CO 80309 USA..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Photon-tagged measurements of jet quenching with ATLAS2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 595-598Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Events containing a high transverse momentum (p(T)) prompt photon offer a useful way to study the dynamics of the hot, dense medium produced in heavy ion collisions. Because photons do not carry color charge, they are unaffected by the medium, and thus provide information about the momentum, direction, and flavor (quark or gluon) of the associated hard-scattered parton before it begins to shower and become quenched. In particular, the presence of a high-p(T) photon can be used to select pp and Pb+Pb events with the same configuration before quenching, limiting the effects of quenching-induced selection biases present in other jet measurements. The large statistics pp and Pb+Pb data delivered by the LHC in 2015 allow for a detailed study of photon-tagged jet quenching effects, such as the overall parton energy loss and modified structure of the component of the shower which remains correlated with the initial parton direction (e.g. in cone). In this proceeding, photon-tagged measurements of jet quenching by ATLAS are reported.

  • 893. Periale, L.
    et al.
    Peskov, V.
    Iacobaeus, C.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    Pavlopoulos, P.
    Picchi, P.
    Pictropaolo, F.
    Tokanai, F.
    Successful operation of hole-type gaseous detectors at cryogenic temperatures2004Inngår i: 2004 IEEE Nuclear Science Symposium Conference Record, 2004, s. 1147-1151Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We have demonstrated that hole-type gaseous detectors, GEMs and capillary plates, can operate up to 77 K. For example, a single capillary plate can operate at gains of above 103 in the entire temperature interval between 300 until 77 K. The same capillary plate combined with Csi photocathodes could operate perfectly well at gains (depending on gas mixtures) of 100-1000. Obtained results may open new fields of applications for capillary plates as detectors of UV light and charge particles at cryogenic temperatures: noble liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogenic PETs.

  • 894. Periale, L.
    et al.
    Peskov, V.
    Iacobaeus, C.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Pavlopoulos, P.
    Picchi, P.
    Pietropaolo, F.
    Tokanai, F.
    The successful operation of hole-type gaseous detectors at cryogenic temperatures2005Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 52, nr 4, s. 927-931Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have demonstrated that hole-type gaseous detectors, gas electron multipliers and capillary plates (CPs) can operate at temperatures down to 77 K. For example, a single CP can operate at gains above 10(3) in the entire temperature interval between 77 and 300 K. The same CP combined with CsI photocathodes operates perfectly well at gains of 100-1000, depending on the gas mixture. The obtained results open new fields of applications for CPs as detectors of ultraviolet light and charged particles at cryogenic temperatures: liquid noble gas time-projection chambers, detectors for weakly interacting massive particles or liquid Xe scintillating calorimeters, and cryogenic positron-emission tomography.

  • 895. Periale, L.
    et al.
    Peskov, V.
    Iacobaeus, C.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Pavlopoulos, P.
    Picchi, P.
    Pietropaolo, F.
    A study of the operation of especially designed photosensitive gaseous detectors at cryogenic temperatures2006Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 567, nr 1, s. 381-385Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In some experiments and applications there is need for large-area photosensitive detectors to operate at cryogenic temperatures. Nowadays, vacuum PMs are usually used for this purpose. We have developed special designs of planar photosensitive gaseous detectors able to operate at cryogenic temperatures. Such detectors are much cheaper than PMs and are almost insensitive to magnetic fields. Results of systematic measurements of their quantum efficiencies, the maximum achievable gains and long-term stabilities will be presented. The successful operation of these detectors open realistic possibilities in replacing PMs by photosensitive gaseous detectors in some applications dealing with cryogenic liquids; for example in experiments using noble liquid TPCs or noble liquid scintillating calorimeters.

  • 896. Periale, L.
    et al.
    Peskov, V.
    Iacobaeus, C.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Picchi, P.
    Pietropaolo, F.
    Rodionov, I.
    Photosensitive gaseous detectors for cryogenic temperature applications2007Inngår 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 1-2, s. 302-305Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are several proposals and projects today for building LXe time projection chambers (TPCs) for dark matter search. Important elements of these TPCs are the photomultipliers operating either inside LXe or in vapours above the liquid. We have recently demonstrated that photosensitive gaseous detectors (wire type and hole type) can operate perfectly well, until temperatures of LN2. In this paper, results of systematic studies of operation of the photosensitive version of these detectors (combined with reflective or semi-transparent CsI photocathodes) in the temperature interval of 300-150K are presented. In particular, it was demonstrated that both sealed and flushed by a gas detectors could operate at a quite stable fashion in a year/time scale. Obtained results strongly indicate that they can be cheap and simple alternatives to photomultipliers or avalanche solid-state detectors in LXe TPC applications.

  • 897. Periale, L.
    et al.
    Peskov, Vladimir
    KTH, Tidigare Institutioner, Fysik.
    Iacobaeus, C.
    Francke, T.
    Lund-Jensen, Bengt
    KTH, Tidigare Institutioner, Fysik.
    Pavlopoulos, N.
    Picchi, P.
    Pietropaolo, F.
    The development of gaseous detectors with solid photocathodes for low-temperature applications2004Inngår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 535, nr 02-jan, s. 517-522Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are several applications and studies in fundamental research, which require the detection of VUV light at cryogenic temperatures. For these applications, we have developed and successfully tested special designs of gaseous detectors with solid photocathodes able to operate at low temperatures: sealed gaseous detectors with MgF2 windows and windowless detectors. We have experimentally demonstrated that both primary and secondary (due to the avalanche multiplication inside liquids) scintillation light can be recorded by photosensitive gaseous detectors. The results of this work may allow one to significantly improve the operation of some noble liquid TPCs.

  • 898. Peskov, V.
    et al.
    Baibussinov, B.
    Centro, S.
    Di Mauro, A.
    Lund-Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Martinengo, P.
    Nappi, E.
    Oliveira, R.
    Pietropaolo, F.
    Picchi, P.
    Periale, L.
    Rodionov, I.
    Ventura, S.
    Development and first tests of GEM-Like detectors with resistive electrodes2007Inngår i: IEEE Transactions on Nuclear Science, ISSN 0018-9499, E-ISSN 1558-1578, Vol. 54, nr 5, s. 1784-1791Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We have developed and tested several prototypes of GEM-like detectors with electrodes coated with resistive layers or completely made of resistive materials. These detectors can operate stably at gains close to 10(5). The resistive layers limit the energy of discharges appearing at higher gains thus making the detectors very robust. We demonstrated that the cathodes of some of these detectors could be coated by CsI or SbCs layers to enhance the detection efficiency for the UV and visible photons. We also discovered that such detectors can operate stably in the cascade mode and high overall gains (similar to 10(6)) are reachable. Applications in several areas, for example in RICH or in noble liquid TPCs are therefore possible. The first results from the detection of UV photons at room and cryogenic temperatures will be given.

  • 899.
    Puri, Akshat
    et al.
    Univ Illinois, Champaign, IL 61820 USA..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik.
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Measurement of angular and momentum distributions of charged particles within and around jets in Pb plus Pb and pp collisions at root s(NN)=5.02 TeV with ATLAS at the LHC2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 177-179Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Studies of the fragmentation of jets into charged particles in heavy-ion collisions can help in understanding the mechanism of jet quenching by the hot and dense QCD matter created in such collisions, the quark-gluon plasma. These proceedings present a measurement of the angular distribution of charged particles around the jet axis in root s(NN) = 5.02 TeV Pb+Pb and pp collisions, done using the ATLAS detector at the LHC. The measurement is performed inside jets reconstructed with the anti-k(t) algorithm with radius parameter R = 0.4, and is extended to regions outside the jet cone. Results are presented as a function of Pb+Pb collision centrality, and both jet and charged-particle transverse momenta.

  • 900.
    Spousta, Martin
    et al.
    Charles Univ Prague, Fac Math & Phys, V Holesovickach 2, Prague 18000, Czech Republic..
    Jensen, Bengt
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ohm, Christian
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Ripellino, Giulia
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Sidebo, P. Edvin
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Strandberg, Jonas
    KTH, Skolan för teknikvetenskap (SCI), Fysik, Partikel- och astropartikelfysik. Royal Inst Technol, Phys Dept, Stockholm, Sweden..
    Zwalinski, L.
    CERN, Geneva, Switzerland..
    Jet suppression and jet substructure in Pb plus Pb and Xe plus Xe collisions with the ATLAS detector2019Inngår i: Nuclear Physics A, ISSN 0375-9474, E-ISSN 1873-1554, Vol. 982, s. 611-614Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This short summary presents latest measurements of the nuclear modification factor, R-AA, for R = 0.4 jets in Pb+Pb collisions at root s(NN) = 5.02 TeV with the ATLAS detector at the LHC. The analysis is performed over a large range of transverse momentum, up to p(T) = 1 TeV, and differentially in jet p(T), rapidity, and collision centrality. The jet R-AA is measured also differentially in the jet mass, m, which provides new information on the dependence of the energy loss on the substructure of jets. Latest results by ATLAS on the dijet momentum balance in Xe+Xe collisions at root s(NN) = 5.44 TeV are presented and compared to the same quantity measured in Pb+Pb collisions at root s(NN) = 5.02 TeV. These recent measurements should help us understand mechanisms of parton energy loss and properties of hot and dense matter created in heavy-ion collisions.

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