Status of the PSD upgrade

1. Status of the PSD upgrade F.Guber, A.Ivashkin, O.Petukhov (INR, Moscow) - Status of the PSD cooling and temperature stabilization system - MAPD gain monitoring system - PSD readout upgrade NA61/SHINEupgrade workshop, CERN3– 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 • The PSD cooling system is not working properly (air flow from underground). • 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. Ebeam =30AGeV Temperature Energy in PSD MAPD gain ~4 %/0C

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

5. Strategy of the PSD upgrade in 2013-2014 • New cooling system. • 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

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

7. Controller TEC -1091 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. 47 TEC controllers have been ordered in Dec.2013 and are now at CERN

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

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

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

11. New FEE and slow control system Al-plate+Armaflex MAPDs SC connector LED source HV channels PCB with amplifiers and adder 10 Analog signals +trigger (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)

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

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

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

16. Matching with readout electronics (present and future variants) Fast Amp. G=30 Signal adapter Slow amp.-integrator DAQ Present variant : MAPD Fast Amp. G=30 (for high energy deposition) DRS Future variant : MAPD Fast Amp. G=120 (for low energy deposition + muon calibration) DRS 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.

17. How many DRS channels are needed? • 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 ms • 44x8=352 DRS channels • Total: 1232 DRS channels.

18. Present problems • 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