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Electromagnetic Calorimeter for HADES at SIS100: MAMI and CERN test results

A. Kr á sa , F. Křížek, A. Kugler , J. Pietraszko , Y. Sobolev , J. Stanislav, P . Tlustý , T. Torrieri (NPI Řež ) , M. Golubeva , F. Guber , A. Ivashkin , K. Lapidus , A. Reshet in (INP Moscow), J. Pietraszko (IKF Frankfurt).

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Electromagnetic Calorimeter for HADES at SIS100: MAMI and CERN test results

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  1. A. Krása, F. Křížek, A. Kugler, J. Pietraszko, Y. Sobolev, J. Stanislav, P. Tlustý, T. Torrieri (NPI Řež) , M. Golubeva, F. Guber, A. Ivashkin, K. Lapidus, A. Reshetin (INP Moscow), J. Pietraszko (IKF Frankfurt) Electromagnetic Calorimeter for HADES at SIS100:MAMI and CERN test results • Lead-glass modules • Tests • - gbeam at MAMI energy resolution • - p-/e- beam at MAMI particle separation • Outlook HADES ECAL Workshop, Frankfurt a.M., October 14-15, 2010

  2. Detector modules Our proposal is to use lead glass modules from OPAL end cap calorimeter. ~ 900 modules needed, at present 1080 modules moved to GSI. Module dimensions: 42 x 9.2 x 9.2 cm Energy resolution ~ 5%/sqrt(E), E in GeV Signal Read-out PMT - EMI 9903KB (1.5'') from MIRAC (WA98 hadron calorimeter) ~720 PMT's diameter – 38 mm (1.5'') diameter of photocathode – 34 mm Front-end readout – ADC ADD-ON (Shower)+ TRB

  3. Detector modules EMI9903KB: 1.5” tube from MIRAC (WA98) H1949: 2.5” tube from HADES Tofino Lead glass dimensions: 9.2 x 9.2 x 42 cm

  4. Tests– cosmic muons Source – cosmicsmuons: energy≈ 2 GeV, energydeposit in module ≈ 200 MeV, Cerenkov lightoutputcorrespondsto≈577 MeVelectrons count rate ≈ 20 particles / hour Measurement of pulse height (ADC) spectra – check ofenergyresolution various PMTs, configurationwith/withoutlightguide July 2009 - testof 5 modulesbeforethe MAMI test November 2009 - testof 5 modules after the MAMI test December 2009 - testofonemodulewith PMTs (same type) withvariousgains, variouswrappings March 2010 – nowtestofmodulesproducedforone LG HADES sector

  5. cosmics - moduleNo.4 July 2009 • s = 5.4 ± 0.2 % Nov. 2009 • s = 5.3 ± 0.2 %

  6. Cosmic tests - results Cherenkov light from cosmicsmuons is equivalent to 577 MeV electrons resolution 6.5% on cosmics corresponds to 5% for electrons at 1000 MeV assuming 5%/sqrt(E), E in GeV

  7. MAMI g beam test conditions Purpose: to measure the module energy resolution as a function of g energy Beam: - detectors were positioned in the secondary gamma beam with continuous energy distribution from 0 to primary electron beam energy, with intensity exponentially falling with increasing energy - unless stated otherwise, the detectors were hit in the centre of their front side, and the beam proceeded along their longitudinal axis - beam diameter at detector position – 6 mm diameter Trigger: OR of signals from 8 selected scintillators in electron tagger – giving events with 8 known gamma energies in range from 0 to energy of the electron beam 2 days of measurement: Ee- = 855 MeV, Ig = 25 kHz 2) Ee- = 1508 MeV, Ig = 5 kHz

  8. MAMI test setup Beam: detectors were positioned in the secondary gamma beam with continuous energy (intensity exponentially falling with increasing energy) Trigger: OR of signals from 8 selected scintillators in electron tagger – giving events with 8 known gamma energies in range from 0 to energy of the electron beam

  9. MAMI test setup Left up: test setup Left down: crew Right: detail with detectors, movable table and beam halo (looking in beam direction)

  10. Measured g spectra ALL E= 1399MeV E= 1210MeV counts E= 1021MeV E= 831MeV E= 676MeV E= 452MeV E= 261MeV E= 72.1MeV ADC channel Ee=1508 MeV, g energy spread <= 1%, det. module No.1

  11. Energy calibration Ee= 1508 MeV

  12. Resolution vs. Energy Ee= 855 MeV resolution ~ k . 1/sqrt(E)

  13. Resolution vs. Energy Ee= 1508 MeV resolution ~ k . 1/sqrt(E)

  14. Resolution vs. Energy Module No.1 resolution ~ k . 1/sqrt(E) LE: Ee= 855 MeV HE: Ee= 1508 MeV cosmics: cosmics muons

  15. Resolution vs. Energy Module No.4 resolution ~ k . 1/sqrt(E) LE: Ee= 855 MeV HE: Ee= 1508 MeV cosmics: cosmics muons

  16. Beam and cosmic tests - results

  17. Resolution vs. HV Ee= 1508 MeV, module No.1 resolution ~ k . 1/sqrt(E)

  18. Resolution vs. beam position Ee= 855 MeV, module No.1 No.1 No.2 01234 reading only module No.1 reading modules No.1+2

  19. CERN p-/e- beam test conditions Purpose: to measure the electron/pion separation as a function of momentum to measure the lead glass module time resolution, 5 identical modules tested (glass+opticalgrease+EMI) Beam: - the T10 test beam line of the CERN PS synchrotron was used - pi- with momenta 0.4 – 6 GeV/c with admixture of electrons (increasing at lower momenta) - detectors were positioned in the pion beam - the detectors were hit in the centre of their front side, and the beam proceeded along their longitudinal axis - beam diameter at detector position – 4x4 cm defined by a trigger scintillator - triggered beam intensity: 100-1000 particles/ bunch, 1 bunch per 45 sec. ID: 2 m long gas Cherenkov in beam, placed 120 cm in front of lead glass, efficiency for electrons 98% Trigger: OR of signals from 2 scintillators 4x4 cm Momentum settings: 0.4-2 GeV/c

  20. Test of lead glass - CERNMay2010 Test setup on T10 CERN PS beam line Beam – pi- with momenta 400-2000MeV/c with admixture of electrons

  21. CERN test setup Right: T10 beam line Left: details with detectors

  22. Measured e/p spectra – CERNMay2010 Red – electrons green – pi- separation via gas Cherenkov ADC channel Electron peaks look worse than gamma peaks at MAMI The electron peak has long energy tail due to energy loss of electrons in air (~15m) and other detectors in T10 area.

  23. Measured e/p spectra – CERNMay2010 ADC channel Same as before, but e/pi- spectra normalized to the same yield

  24. e/p separation 2 sigma cut set on the electron peak Ratio of pions outside the cut to all pions is plotted For “RPC” the time-of-flight is used with assumed resolution of 100 ps (sigma) SHOWER

  25. Energy resolution – CERNMay2010 Ee [MeV] Looks a little worse than for gamma beam test – The electron peak has long energy tail due to energy loss of electrons in air (~15m) and other detectors in T10 area.

  26. Time resolution – CERNMay2010 e- 800 MeV START signal – quarz detector, resolution < 100 ps TDC gain – 50 ps / channel

  27. Summary • detector prototypes tested by •  cosmic muons • gamma beam • pion/electron beam • results • optimal detector configuration found •  detector energy resolution close to 5% at 1 GeV  e/p separation better than the SHOWER detector, in combination with RPC excellent separation •  detector time resolution 215 ps (sigma)

  28. Design • Number of modules 150x6=900 • Mass of one module of lead-glass14 kg • Total mass of cal. 12600 kg E. Lisowski, TU Krakow

  29. Cosmic test setup lead glass module trigger detectors count rate: ~ 20 particles / hour

  30. Cosmic muon ADC spectra our data Fermilab E760 Central Calorimeter module length 50 cm σ/Nmean= 5.4 % σ/Nmean≈ 7 % OPAL e- 1 GeV Np.e.≈ 1800 s ≈ 5% E760 e- 1 GeV Np.e.≈ 4250 s ≈ 5% E760 m≈ 2 GeV Np.e.≈ 2082 s ≈ 7% http://www.e835.to.infn.it/people/gollwitz/thesis/ K. Gollwitzer, PhD thesis, University of California at Irvine, 1993

  31. PMT Tests PMT EMI 9903KB (1.5'') ~720 PMTs available 500 PMTs tested HV dependence of PMT response: PMT alone at HV=1500 and 1700 V, PMT with a gamma-source 22Na at HV=1200, 1500, and 1700 V; The results for HV=1500 V: <500 mV 79 pieces of PMTs 16% 500 mV < U < 1500 mV 120 pieces of PMTs 1500 mV < U < 2700 mV 191 pieces of PMTs >2700 mV 110 pieces of PMTs

  32. Energy resolution and hadron rejection of the OPAL end cap calorimeter Energy resolution of the OPAL lead glass modules is 5%/sqrt(E), E in GeV) Hadron rejection below 10 GeV was not measured.

  33. Simulated e/p spectra K. Lapidus

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