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Träfflista för sökning "WFRF:(Nácher E.) srt2:(2005-2009)"

Search: WFRF:(Nácher E.) > (2005-2009)

  • Result 1-6 of 6
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1.
  • Abdesselam, A., et al. (author)
  • Engineering for the ATLAS SemiConductor Tracker (SCT) end-cap
  • 2008
  • In: Journal of Instrumentation. - 1748-0221. ; 3
  • Journal article (peer-reviewed)abstract
    • The ATLAS SemiConductor Tracker (SCT) is a silicon-strip tracking detector which forms part of the ATLAS inner detector. The SCT is designed to track charged particles produced in proton-proton collisions at the Large Hadron Collider (LHC) at CERN at an energy of 14 TeV. The tracker is made up of a central barrel and two identical end-caps. The barrel contains 2112 silicon modules, while each end-cap contains 988 modules. The overall tracking performance depends not only on the intrinsic measurement precision of the modules but also on the characteristics of the whole assembly, in particular, the stability and the total material budget. This paper describes the engineering design and construction of the SCT end-caps, which are required to support mechanically the silicon modules, supply services to them and provide a suitable environment within the inner detector. Critical engineering choices are highlighted and innovative solutions are presented - these will be of interest to other builders of large-scale tracking detectors. The SCT end-caps will be fully connected at the start of 2008. Further commissioning will continue, to be ready for proton-proton collision data in 2008.
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2.
  • Abdesselam, A., et al. (author)
  • The ATLAS semiconductor tracker end-cap module
  • 2007
  • In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 575:3, s. 353-389
  • Journal article (peer-reviewed)abstract
    • The challenges for the tracking detector systems at the LHC are unprecedented in terms of the number of channels, the required read-out speed and the expected radiation levels. The ATLAS Semiconductor Tracker. (SCT) end-caps have a total of about 3 million electronics channels each reading out every 25 ns into its own on-chip 3.3 mu s buffer. The highest anticipated dose after 10 years operation is 1.4x10(14) cm(-2) in units of 1 MeV neutron equivalent (assuming the damage factors scale with the non-ionising energy loss). The forward tracker has 1976 double-sided modules, mostly of area similar to 70 cm(2), each having 2 x 768 strips read out by six ASICs per side. The requirement to achieve an average perpendicular radiation length of 1.5% X-0, while coping with up to 7 W dissipation per module (after irradiation), leads to stringent constraints on the thermal design. The additional requirement of 1500e(-) equivalent noise charge (ENC) rising to only 1800e(-) ENC after irradiation, provides stringent design constraints on both the high-density Cu/Polyimide flex read-out circuit and the ABCD3TA read-out ASICs. Finally, the accuracy of module assembly must not compromise the 16 mu m (r phi) resolution perpendicular to the strip directions or 580 mu m radial resolution coming from the 40 mrad front-back stereo angle. A total of 2210 modules were built to the tight tolerances and specifications required for the SCT. This was 234 more than the 1976 required and represents a yield of 93%. The component flow was at times tight, but the module production rate of 40-50 per week was maintained despite this. The distributed production was not found to be a major logistical problem and it allowed additional flexibility to take advantage of where the effort was available, including any spare capacity, for building the end-cap modules. The collaboration that produced the ATLAS SCT end-cap modules kept in close contact at all times so that the effects of shortages or stoppages at different sites could be rapidly resolved.
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3.
  • Gadea, A, et al. (author)
  • Hindered E4 decay of the 12(+) yrast trap in Fe-52
  • 2005
  • In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 619:1-2, s. 88-94
  • Journal article (peer-reviewed)abstract
    • The gamma decay of the 12(+) yrast trap in Fe-52 has been measured for the first time. The two E4 gamma-branches to the 8(+) states are hindered with respect to other B(E4) reduced transition probabilities measured in the f(7/2) shell. The interpretation of the data is given in the full pf shell model framework, comparing the results obtained with different residual interactions. It is shown that measurements of hexadecapole transition probabilities constitute a powerful tool in discriminating the correct configuration of the involved wavefunctions.
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4.
  • Ruchowska, E., et al. (author)
  • Nuclear structure of Th-229
  • 2006
  • In: Physical Review C. Nuclear Physics. - : American Physical Society. - 0556-2813 .- 1089-490X. ; 73:4
  • Journal article (peer-reviewed)abstract
    • Lifetimes of excited states in Th-229, populated in the beta decay of Ac-229, have been measured using the advanced time-delayed beta gamma gamma(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new gamma lines have been introduced into the beta-decay scheme of Ac-229 based on results of gamma gamma coincidence measurements. Reduced transition probabilities have been determined for more than 70 gamma transitions in Th-229. Average parallel to D-0 parallel to values of 0.029(1), 0.077(3), and 0.024(5) e fm have been deduced for the lowest K-pi=1/2(+/-),3/2(+/-), and 5/2(+/-) parity partner bands, respectively. Excited states in Th-229 and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, 3/2(+) isomeric state is predicted to be about 10 h. Potential energy surfaces on the (beta(2),beta(3)) plane for the lowest single quasiparticle configurations in Th-229 have been calculated using the Strutinsky method.
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5.
  • Gadea, A., et al. (author)
  • Observation of Ni-54 : Cross-conjugate symmetry in f(7/2) mirror energy differences
  • 2006
  • In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 97:15, s. 152501-
  • Journal article (peer-reviewed)abstract
    • Gamma decays from excited states up to J(pi)=6(+) in the N=Z-2 nucleus Ni-54 have been identified for the first time. Level energies are compared with those of the isobars Co-54 and Fe-54 and of the cross-conjugate nuclei of mass A=42. The good but puzzling f(7/2) cross-conjugate symmetry in mirror and triplet energy differences is analyzed. Shell model calculations reproduce the new data but the necessary nuclear charge-dependent phenomenology is not fully explained by modern nucleon-nucleon potentials.
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6.
  • Caballero, L., et al. (author)
  • Two-phonon octupole excitation in 146Gd
  • 2006
  • In: AIP Conf. Proc.. - : AIP. - 0735403236 - 9780735403239 ; , s. 213-216
  • Conference paper (peer-reviewed)abstract
    • The excited states in 146Gd have been re-investigated with the 144Sm(α,2n) reaction using a modern Ge γ-ray array including a polarimeter. Amongst the non-yrast states populated in this reaction we have identified the aligned 6 + member of the two-phonon octupole quartet from the observation of the E3 branching to the one phonon 3 - state. Our results represent the first observation of a 6 +→ 3 -→0 + E3 cascade in an even-even nucleus.
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  • Result 1-6 of 6

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