1. SBS Hadron and Electron Calorimeters Mark Jones 1 TexPoint fonts used in EMF. Read the TexPoint manual before you delete this box.: AAA A

2. SBS Hadron and Electron Calorimeters Mark Jones Overview of GEn, GMn setup Overview of GEp setup The SBS hadron calorimeter (HCalo) Design of HCalo Neutron and proton detection efficiency, energy and position resolution BigCal for GEp (not part of this technical review) 2

3. Experiment Setup for GEn and GMn  Use standard BigBite double layer calorimeter Electron PID (combined with gas Cherenkov). Electron energies in range from 1.2 to 3.5 GeV. High threshold for trigger.  Hadron calorimeter based on successful design used in COMPASS. Proton and Neutron momentum from 2.6 to 10.5 GeV/c Need good position (angular) resolution to separate (quasi-) elastic from inelastic background. 3

4. Experiment Setup for GEp  Reconfigure BigCal for electron detection. Electron momentum range from 3.3 to 3.9 GeV/c Use 20cm thick Al wall to reduce flux of low energy background. High threshold to reduce single arm trigger rate. Position resolution needed in track reconstruction ( L. Pentchev’s talk)  Use same Hadron calorimeter Proton momentum range from 3.5 to 8.6 GeV/c High threshold to reduce the single arm trigger rate Position resolution needed in track reconstruction 4

5. Module of Hadron Calorimeter As starting point, use COMPASS design of JINR group. Iron and scintillator sandwich 5

6. Module of Hadron Calorimeter  Carnegie Mellon and JINR will design and build calorimeter. Optimize length for the experiment’s energy range Improve timing resolution. o COMPASS  t = 1.5ns o Expect to reach  t = 0.4ns 6

7. Hadron Calorimeter (Hcalo) Each block has frontal area 15x15 cm 2 Arrange 11x22 blocks Area = 5.5 m 2 Total weight is 36 tons (w/o frame) 7

8. COMPASS HCalo Performance Position resolution In range of 2-10 GeV/c  E/E = 20-30% Energy resolution 8

9. GEANT study of HCalo Performance  Response of neutrons and protons nearly identical  Good energy resolution 9

10. GEANT study of HCalo Performance  Response of neutrons and protons nearly identical  Good energy resolution High thresholds reduce backgrounds GMn: Near identical p/n efficiency reduces systematics 10

11. GEANT study of HCalo Performance  Response of neutrons and protons nearly identical  Good position resolution GMn, GEn, GEp: Cut on  nq to separate (quasi-)elastic events GEp : Need for track reconstruction, reduce pseudo-tracks 11

12. BigCal for GEp experiment Used in Hall C Gep3 experiment 12

13. BigCal performance in Hall C GEp3 13 Comparison of energy resolution from GEANT simulation to data for different electron energies and thicknesses of Al plate Agreement between GEANT and data is excellent

14. BigCal performance in Hall C GEp3 14 x cal is measured BigCal horizontal coordinate x HMS is predicted position from beam energy & proton momentum  x HMS = 0.9 cm  x cal = 0.55 cm x diff = x cal -x HMS

15. BigCal for GEp  Reassemble 20 x 76 block array. 1520 blocks  Block size is 4x4x40 and 3.8x3.8x45 cm 3  Covers area of 0.80 x 3.04 = 2.4 m 2 76 20 15

16. BigCal electronics 76 20  Make groups of 4x2 blocks  Use NIM “summing” modules (special built for and used in Hall C experiment) which have: 8 analog inputs 8 analog outputs (amplify 5x) 6 “sum of 8” analog outputs 16

17. BigCal electronics  Each red block is 4x2 grouping into NIM “summing” module.  Need 5x38 = 190 modules (available) 38 5 17

18. BigCal electronics  For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)  Blue box represents one “group of 32” 38 5 18

19. BigCal electronics  For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)  Blue box represents one “group of 32”  Turquoise box is next “group of 32” in vertical which overlaps by 2 rows. 38 5 19

20. BigCal electronics  For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)  Blue box represents one “group of 32”  Turquoise box is next “group of 32” in vertical which overlaps by 2 rows.  Dark green is next group 38 5 20

21. BigCal electronics  For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)  Most “groups of 8” are in 4 “groups of 32” 38 5 21

22. BigCal electronics  Each dot is the center of “group of 32”  Have 4x37 = 148 “group of 32” which will be used in trigger.  Trigger discussed in O. Hansen’s talk. 37 4 22

23. Conclusions  Hadron Calorimeter Used in all three form factor experiments. Based on the proven COMPASS design. Energy resolution allows high thresholds to eliminate background and lower trigger rates Position resolution allows for good angular resolution o Needed in all FF experiments to separate (quasi-)elastic from inelastic o Needed in GEp to help in tracking with large low-energy background rates Neutron and proton response above 2.5 GeV/c nearly identical  Electron Calorimeter GEn and GMn use standard BigBite calorimeter GEp uses a reconfigured BigCal calorimeter High threshold reduces trigger rate Position resolution needed for tracking and separating (quasi-) elastic from inelastic. 23

24. Backup Slides 24

25. GEANT study of HCalo Performance Response of neutrons and protons nearly identical F. F. Benmokhtar Protons Neutrons 2.5 GeV/c 3.2 GeV/c 4.0 GeV/c 5.4 GeV/c 6.2 GeV/c 7.3 GeV/c 8.1 GeV/c 9.4 GeV/c 10.5 GeV/c 25

26. GEANT study of HCalo Performance Response of neutrons and protons nearly identical Good energy resolution High thresholds reduce backgrounds GMn: Near identical p/n efficiency reduces systematics F. Benmokhtar 26

27. GEANT study of HCalo Performance Response of neutrons and protons nearly identical Good position resolution GMn, GEn, GEp: Cut on  nq to separate quasi-elastic events GEp : Need for track reconstruction, reduce pseudo-tracks F. F. Benmokhtar 27

28. COMPASS HCalo Performance Muons Pions Extensive tests of calorimeter performance were done at CERN for pions, electrons and muons at 2-100 GeV Calibrated energy spectra for 10 GeV beam 28

29. COMPASS Hcalo 29

30. GEp experiment 30

31. GEp experiment: Radiation Damage 31

32. GEp experiment: Radiation Damage 32

33. GEn experiment 33

34. GMn experiment 34

35. GMn experiment 35

36. Geant study of HCalo Performance Response of neutrons and protons nearly identical Good position resolution GMn, GEn, GEp: Cut on Qnq to separate quasi-elastic events GEp : Need for track reconstruction, reduce pseudo-tracks Good energy resolution High thresholds reduce backgrounds GMn: Near identical p/n efficiency reduces systematics 36