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Degrader

GSI’s Fragment Separator (FRS). Degrader. 58 Ni Beam. EM. miniCAL. Fragments. Target. Cocktail beam at 1.7 GeV/nucleon. Minical. miniCAL: 8 layers of 3 logs each already used at CERN in august crystals from Kalmar, Saclay, Bordeaux CDEs made at Saclay (same as for EM)

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Degrader

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  1. GSI’s Fragment Separator (FRS) Degrader 58Ni Beam EM miniCAL Fragments Target Cocktail beam at 1.7 GeV/nucleon

  2. Minical miniCAL: 8 layers of 3 logs each already used at CERN in august crystals from Kalmar, Saclay, Bordeaux CDEs made at Saclay (same as for EM) electronics: Bordeaux FRS trigger plastic Cocktail beam, 1.7 GeV/nucleon

  3. EM results Cocktail beam at 1.7 GeV/nucleon Nhit

  4. Z-dependent position This is not a bug: it’s a feature.

  5. There is a real bug in the EM trigger! Same number of events in two (FRS & EM) data streams External trigger worked fine. Did it? only about 40% of ions found in the peak in the first layer! Almost 80% for minical. 50% of events

  6. Analysis Status (Bordeaux) • FRS: calibration in Z, A • miniCAL: • - energy calibration: protons + charge injection • - quenching factors • - cross sections for charge-changing reactions • EM • - correction for non-linearity in EM electronics • - energy calibration: • - protons for LEX8 • - cross calibration with real data for LEX1, • HEX8, HEX1 • - comparison with Sasha’s coefficients • - quenching factors • - cross sections for charge-changing reactions • simulations (standalone GEANT4 v6.0): • ionisation energy deposit for protons & ions

  7. Calculated energy deposit(taken from Thierry’ s note) Carbon SRIM-G4: 1% difference Proton • SRIM-G4: • 10% for 1 mm • 5% for 20 mm G4 may underestimateDE for protons

  8. LEX8 absolute energy calibration with protons Position: X=6 Y=6 (run 165) blue: G4+broadening (0.65 MeV) black:data

  9. Cross calibration HEX8/LEX1 LEX1 vs HEX8 X Y X Y Ratio

  10. Comparison with Sasha’s coefficients Gain (MeV/channel) Proton gain/muon gain Layer Layer

  11. The Alpha run Run 178 « X=6 Y=6 » but the alphas hit the Y=8 crystal! X Y X Y R  L

  12. The Alpha run (2) Protons and a do not hit at the same location. Correcting for this effect, the measured energy deposit for a is 9% (50.0 MeV instead of 45.9 MeV) too high as compared to the G4 predictions. a Left vs Right amplitudes p X Y

  13. Peak determination Z=14 Hit multiplicity

  14. Quenching For low Z ions, an « anti-quenching » effect (>20%) is observed.

  15. Quenching (2)

  16. EM vs minical comparison 2% minical EM

  17. Minical calibration coefficients Comparison with calibration values established at CERN with 20 GeV muons

  18. Longitudinal shower profiles measured at CERN 50 GeV 1.3 X0 80 GeV 1.3 X0 120 GeV 0 X0 120 GeV 4 X0 120 GeV 8 X0

  19. Cross sections determination Ionisation peaks: « non-interacting » events

  20. Cross sections determination (2) Psurvival= exp(-xsr) minical x: depth s: reaction cross section r: density Z=8 Z=14 Z=20 Z=26

  21. Measured cross sections

  22. « Things to be done » list • Look into EM trigger problem • Investigate effects of cuts • Position studies • Nuclear reactions studies (we have protons and alphas as well) • And there are the great many runs using different conditions • we have not looked at.

  23. FRS ion identification

  24. MiniCAL results Cocktail beam at 1.7 GeV/nucleon Non-linearity manifests the quenching effect!

  25. MiniCAL absolute-energy calibration

  26. EM results Cocktail beam at 1.7 GeV/nucleon

  27. Hit distribution

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