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Degrader

GSI experiment (November 14-24,2003). Degrader. 58 Ni Beam. 1st dipole pair. 2nd dipole pair. Fragments. EM. Target. FRS: FR agment S eparator at GSI Darmstadt, Germany One single beam: 58 Ni, with energy varying between .1 and 1.7 GeV/nucleon .

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Degrader

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  1. GSI experiment (November 14-24,2003) Degrader 58Ni Beam 1st dipole pair 2nd dipole pair Fragments EM Target FRS:FRagment Separator at GSI Darmstadt, Germany One single beam:58Ni, with energy varying between .1 and 1.7 GeV/nucleon. All fragments lighter than Ni are produced in the target, sorted out by the spectrometer (magnetic rigidity) and identified (Z,A,E) thanks to the detection system. Plan: different energies and EM angles, all elements (2<Z<26) dedicated runs with specific ions: C, Si, Fe (use of “degrader”) Issue: Synchronisation of two data streams Slide 1

  2. Goals of the GSI experiment Goals: C Simulated GCR Eloss distributions in orbit Counts O • Determination of dL/dE as a function of (E,Z) • Test of the algorithms for rejection of reaction events: • heavy ions + lighter ions (alphas…) • Test of the EM’s response to real, high-energy events • (comparison with detectors • fitted with good electronics) Si Fe Side benefit: Eloss (MeV) Slide 2

  3. Quenching Effects: dL/dE Birk’s formula: L(E)E/(1+kB dE/dx) High energy: for a given dE/dx, E is higher for greater Z more d electrons less quenching exemple of functional: L(E)DE (1- X ln(1+X-1)+ bAZ2 ln((1+X)/(X+cA/E))) with X=a AZ2/E NaI(Tl) “punchthrough point” “relativistic rise” upper limit at GSI lower limit at GSI Ganil Salamon and Ahlen Slide 3

  4. GANIL experiment (Easter 2003) 73 MeV/nucleon 78Kr+Au, Pb targets « no quenching » 2 CsI bars (hidden) 6 Si detectors VERY PRELIMINARY results E estimated from Si Energy loss E in CsI deduced from Eloss in Si (loss in wrapping foil taken into account) Effect of shaping time (0.5 –2 –6 ms) also investigated Slide 4

  5. Nuclear reactions: rejection • Will be tested with GSI data: 1.7 GeV Fe will « punch » through the whole • calorimeter at normal incidence. • Rejection algorithms based on: • Ei/E i+1 ratios, significantly different from 1 (thresh: TBD) for reactions • charge-changing (« stripping ») reactions: Z  Z-1: DE/E ~1/Z = 4% for Fe • presence of energy in neighboring crystals • Numbers of identified reactions can be confronted with expected (= real!) values • from empirical cross sections Simulations: JQMD, INC in GEANT4, Fluka? Slide 5

  6. CERN-SPS experiment in 2003 (August 7-13) • Goals: • precise measurement of longitudinal shower profile (~20 X0) • test of energy-reconstruction methods • investigation of crack effects (2 detector subsets) • investigation of the impact of direct energy deposit within • photodiodes on position determination • determination of nuclear-reaction patterns (pion-induced reactions) • verification of CsI time constants • Beams (H6a line) : electrons 6 GeV<E<150 GeV • pions+muons • Setup: « Cal »: at least 32 crystals (50 proposed by Sweden) • trigger: 2cm x 2cm plastic scintillator • position: Si strips (?) Slide 6

  7. CERN-SPS experiment in 2002 detector (2x4 CsI crystals) Pb 511 keV 1.275 MeV “sum” Longitudinal shower profile (calibration with muons…) Good electronics Slide 7

  8. Transverse “shower profile” at 200 GeV Slide 8

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