1. Status of the PSD upgrade - Status of the PSD cooling and temperature stabilization system - MAPD gain monitoring system - PSD readout upgrade F.Guber, A.Ivashkin, O.Petukhov (INR, Moscow) 1 NA61/SHINE upgrade workshop, CERN 3– 5 March, 2014

2. History of PSD construction at NA61 PSD is the first calorimeter with new type of photodetectors – SiPMs (MAPDs). The concept test in 2007. Active phase of construction in 2010-2012. Start of data taking in 2011 in truncated mode before the full construction. Fully assembled in 2012 a few months before the physical run. 44 modules with 440 MAPDs Little experience with MAPD. Very tight time schedule of construction. Minimum control functionality. PSD modules in 2011 Be-run

3. Problems with PSD in Be-runs 1.The PSD cooling system is not working properly (air flow from underground). 2.The temperature control system is not working properly 3. HV control system does not readout MAPD voltages (minimum functionality). 4. No monitoring system for the MAPD gains (minimum functionality). 5. The rise time of PSD trigger signal is slow – problem with the time-amplitude walk and signal delay in trigger box. 6. Electronics noises are rather small but comparable with MIPs signal. It makes problem with muon calibration. E beam =30AGeV Energy in PSD Temperature MAPD gain ~4 %/ 0 C

4. PSD FEE before upgrade Analog part Digital part Readout part Three parts – three boards +80V DAQ

5. Strategy of the PSD upgrade in 2013-2014 1.New cooling system. 2.New temperature control system. 3. New HV control (readout of real voltages). 4. Monitoring system for the MAPD gains (LED stabilized source). 5. New PSD trigger signal after fast amplifiers. 6. New readout system (fast amplifiers+ DRS4) and/or compatibility with existing readout. the rare side of the PSD without FEE 5

6. PELTIER COOLER Scheme of MAPDs temperature stabilization by Peltier element Heat sink Temperature sensor Copper heat sink Al plate External TEC controller PSD module electronics Compressed air T s -sink temperature sensor T o -object temperature seensor ToTo TsTs 6

7. Controller TEC -1091 47 TEC controllers have been ordered in Dec.2013 and are now at CERN The TEC-1091 is a specialized TEC controller / power supply able to precision-drive Peltier elements. It features a true bipolar current source for cooling / heating, two temperature monitoring inputs (1x high precision, 1x auxiliary) and intelligent PID control with auto tuning. The TEC-1091 is fully digitally controller.

8. Fully assembled cooling system, FEE, HV and control system for one module

9. 9 First, assembling and tests on the table Then. Install in the modules….. New electronics + cooling system

10. 10 Cooling system test results (48 hours) Room temperature T Al plate vs time

11. New FEE and slow control system MAPDs Al-plate+Armaflex LED source HV channels 10 Analog signals +trigger (adder) SC connector PCB with amplifiers and adder Successfully tested in October. Mass production is finished - 50 sets are ready. 30 sets have been tested, 20 sets will be tested in Moscow (March) 11

12. Old PSD FEE after upgrade Analog part Digital part Readout part Only readout part will be used as interface with DAQ +80V DAQ

13. MAPDs gain monitoring system Light amplitude is controlled by PIN- diode inside with very low temperature dependence. Control of MAPD gain at <1% level Based on stabilized LED source. 13 Digitized LED signal Time, bin A, ch LED amplitude spectra  E /E~2% Time amplitude stability ~1%

14. New slow control system. Originally developed for COMPASS ECAL Can control up to 127 devices (modules). Can control the gain monitoring system too. Connection with external computer: USB-2.0 or RS-232. Internal bus: RS485 Maximum length of bus cables: 50 m Controller for SC New HV distribution system Extremely low power consumption. HV stability – 0.01%. One external power supply ~12 V. Permanent check of correct HV values within given HV gate - There is feedback to HV values! Already tested for a few years! ! Developer - HVSys Co., Dubna. 14

15. Trigger problem is solved 15 Signal shape after adder. Rise time ~10 ns No time walk! No extra delay of trigger signals! Present scheme: MAPD Fast Amp. G=30 Adder

16. Matching with readout electronics (present and future variants) 16 Two amplifiers increase the dynamical range of detected energies. (especially important for heavy ion program). The saturation amplitude of amp. is about 2.5 V. Additional divider can be installed after Low gain Amp. to reduce amplitude to 1 V. Higher dynamic range. Present variant : MAPD Fast Amp. G=30 Signal adapter Slow amp.- integrator DAQ Future variant : MAPD Fast Amp. G=30 DRS Fast Amp. G=120 DRS (for high energy deposition) (for low energy deposition + muon calibration)

17. How many DRS channels are needed? 17 440 MAPDs in PSD. 440x2=880 DRS readout channels for individual MAPD readout. For pile-up identification adder signal is used in the time window 8  s 44x8=352 DRS channels Total: 1232 DRS channels.

18. Present problems 18 The noise level of digitized signals in old MB is higher for a factor of 2-3 after installation of new FEE. Needs work with grounds, power supplies. How to match the LED monitoring system to DAQ? How often it would be used? Initial version of slow control (HV, LED) is under development. Full version is needed. Slow control on Peltier elements is needed. Future problems How many DRS channels for PSD can be used? How to implement PSD Slow control to NA61? Cables, connectors, patch-panel?

19. Thank You 19