1. PANDA electromagnetic calorimeters Pavel Semenov IHEP, Protvino on behalf of the IHEP PANDA group INSTR08 28 Feb - 05 Mar 2008

2. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk2 Outline PANDA detector setup Target Spectrometer EMC –PANDA gamma irradiation facility at IHEP –Light output at -20 ° C –Radiation hardness measurements at -20 ° C Forward Spectrometer EMC –EMC prototype module parameters –Prototype testbeam results for energy and position resolution –MC studies to find optimal parameters

3. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk3 PANDA EM Calorimeters placement FS EMC TS EMC

4. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk4 Target spectrometer EMC Requirements –Geometrical coverage close to 4π –Compact size –Fast signal, good time resolution –Low energy threshold (10 MeV) of photon detection –Excellent position and energy resolutions PbWO4 (PWO) crystal as a good candidate for the TS EMC –21 mm x 21 mm x 20 cm barrel cell size (front), 25 mm x 25 mm x 20 cm endcap cell cize –~17000 crystals (96 % of 4 π) Improved light output is needed to reach excellent resolution and low threshold –Calorimeter operates at low temperature (about -20 0 C, factor of 3 increase of light output) –PWO-II: enhanced light output PWO (~20 phe/MeV) PWO radiation hardness at room temperature is not a problem for PANDA (dose rates not more then a few rad/hour). But there were no data for PWO radiation hardness properties at -20 0 C

5. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk5 PANDA-IF at IHEP features Crystal holder (Cu plate with heat-exchanging system) for 5 crystals Cryothermostat (LAUDA RC6CP) capable of temperature stabilization in the region of -35 °C --- +200 °C LED system to monitor PMT gain and crystals transparency in blue and red part of the visible spectrum Cs137 gamma source gives irradiation dose rate 100 rad/h and below Monitoring of temperature sensors ( Pt100 and Pt1000 class A ) at 6 points (2 on crystals)

6. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk6 PANDA-IF picture Cryothermostat Crystal box

7. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk7 PWO properties studies at low temperatures Crystal # S(-19.4) / S(+18.5) b4b4 2.83 b16 2.80 b17 2.75 b24 2.78 b30 2.84 Light output change before the irradiation with temperature change from +18.5 0 C to -19.4 0 C Radiation hardness studies of PWO-II at PANDA dose rates (max 2 rad/hour) and -20 0 C showed 20%-35% drop of DC output signal after 300-400 hours of irradiation

8. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk8 PWO light transmittance recovery at -20 0 C Published at NIM A Vol 582/2 pp 575-580 Paper: First study of radiation hardness of lead tungstate crystals at low temperatures

9. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk9 Radiation hardness studies of PWO-II (high dose rate) Still factor 1.4 enhancement of light output

10. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk10 Forward Spectrometer EMC 7 meters from the interaction point Covers 3 m 2 Fine segmented sampling calorimeter with light collection by optical WLS fibers passing through holes in the scintillator and lead layers (shashlyk type) Not in magnetic field (PMT as photodetector) Working energy range 10 MeV – 10 GeV

11. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk11 Testbeam setup DC1 M14DC2 DC3 DC4 ECAL prototype Beam Spectrometer consisted of 4 drift chamber stations and a magnet to measure beam particle momentum precisely Calorimeter prototype installed on a movable platform

12. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk12 Shashlyk prototype module parameters 9 modules assembled in matrix 3x3 380 layers of 0.3-mm lead and 1.5-mm scintillator, total length 680 mm Transverse size 110x110 mm 2 Effective Moliere radius: R M =59 mm Effective radiation length: X 0 =34 mm Total radiation length: 20X 0 Light collection: 144 (12  12) fibers BCF-91A (  1.2 mm) PMT Hamamtsu R5800 as photodetectors

13. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk13 Shashlyk modules production

14. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk14 Shashlyk prototype pictures 3x3 matrix of shashlyk modules and PMT attached to the modules

15. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk15 Minimum ionizing particle peak

16. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk16 Energy Resolution dependence on energy

17. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk17 Energy Resolution parameterization σ E /E = a/E  b/√E  c [%], E in GeV Experiment data fit: MC data fit: a = 3.5 ± 0.3 a = 0.0 b = 2.8 ± 0.2 b = 3.0 ± 0.3 c = 1.3 ± 0.04 c = 1.1 ± 0.7 Good agreement with MC without noise term. Good agreement with previous studies of similar sampling modules at lower energies (2.9%/ √E at 220-370 MeV: Test beam study of the KOPIO shashlyk calorimeter prototype, G.Atoian, S.Dhawan,V.Issakov et al. CALOR-2004 Proceedings )

18. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk18 Measured S-curve at 19 GeV Real Position, cm Xcog,au

19. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk19 Position resolution (center) dependence on energy

20. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk20 Position resolution parameterization σ x = a/√E  b [mm], E in GeV Experiment data fit: MC data fit: a = 17.6 ± 0.9 a = 14.2 ± 0.6 b = 4.6 ± 0.9 b = 5.5 ± 0.9 Worst case – resolution at the module center. Resolution near the module edge is 3 times better

21. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk21 Shashlyk 8x8 cells prototype We plan to have another shashlyk testbeam run in 2008 with prototype of 8x8 cells Now prototype with 55mm x 55mm module sizes is under construction Testbeam studies includes prototype energy and position resolution as well as test of π 0 reconstruction capabilities in the energy range up to 15 GeV

22. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk22 Conclusions PWO-II radiation hardness at -20 0 C studies showed deep light transmission drop (20%-35% at 2rad/hour) and low light transmission recovery rate Testbeam studies of energy and position resolution of shashlyk prototype (110x110mm cell) results: –Energy σ E /E = 3.5/E  2.8/√E  1.3 [%] –Position (at the cell center) σ x = 17.6/√E  4.6 [mm] –Good agreement with MC results Further improvement of shashlyk parameters includes prototype with 55x55 mm cell size testbeam study

23. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk23 Backup slides

24. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk24 Radiation hardness temperature dependence

25. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk25 MC shashlyk parameters Shashlyk module geometry including holes Tile att. length 70 cm Fiber att length 400 cm Reflection from tile edges diffusive Tot. internal reflection 0.97 Tile light output 100 eV/photon Reemission probability in fiber 0.1 Refraction in tiles and fibers 1.59

26. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk26 S-curve MC (0.5 – 10 GeV)

27. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk27 PANDA-IF electronics Based on i7k (ICP DAS) modules with RS485 interface Short connections (0.5 m) from PMT and temperature sensors to read-out electronics Temperature measurements with an accuracy better than 0.03 °C DC current measurements accuracy up to nA LED signals in DC mode – measurement of the mean current thru 10 kΩ generated by a bunch of pulses HV for PMTs: LeCroy1440 system

28. 3 March 2008Pavel Semenov, INSTR08@BINP, Novosibirsk28 PANDA-IF electronics diagram 7013 PT1000 CAMAC RS485 bus Irradiation facility Control room 7017 ADC 7042 DO LED generator HV Crystal Box Shutter LRS1440 HV system VME Shutter digital control lines RS232 DAQ computer Linux RS485/RS232 converter LAUDA PT1000 7 signal lines Opt. fibers RS232- CL Cs 137