T979: Si-Pms in MTest

1. T979: Si-Pms in MTest Anatoly Ronzhin, Fermilab, AEM 12 April, 2010 The team: Mike Albrow, Marcel Demarteau, Sergey Los, Sasha Pronko, Erik Ramberg, Hans Wenzel, Fermilab AndriyZatserklyaniy, University of Puerto Rico Sarah Malik, Rockefeller University Sarah is the new member of our picosecond test beam community (“picoclub”).

2. SiDet preparation before the test beam All the “pico” test beam equipment: dark boxes with Faraday cages, trigger and veto counters, SiPms assembly, micrometric detector’s supports, tools for alignment were prepared and tested at SiDet. Extensive study of Ortec VT120, CFD9327, TAC566, 567. SMA: attenuators, cables, splitters, (including influence of cable type and length on the time resolution) before the test beam. For the “pico” TOF all cables, connectors, adapters deserve special consideration. E.g., it was found that 14 meters of cables length of the 9327 NIM out does not worsen “electrical” time resolution, (about 1ch=3.1ps). Timing parameters of SiPms, Photek 240, 210, also as SPTR (single photoelectron time resolution), its dependence on HV, were obtained with PiLas laser (with both 405 nm and 635 nm heads). SiPm’s clipping schematics investigated. Requirements for temperature and bias voltage stability defined. Consistency with test beam data observed. Power supplies (HV, LV), for both SiPms and Photeks were defined, tested before the test beam. DAQ was prepared, tested (including AD114 and 2249A readout). This allowed to complete our program in timely fashion. 2

3. Why SiPms for the fast TOF application? • the avalanche spread is very fast (SPTR, another term isTTS), at the level of 100 ps or even better. Our SPTR measurements at SiDet approved it. • perfect single photoelectrons spectra, allow easy calibration. • QE for the blue light is at the level of 65% (for TOF we don’t care too much about optical crosstalk). But we also studied SiPm with tranches. • non sensitivity to magnetic field, what extend SiPm TOF application. • low amount of material introduced into the particle’s path to get few tens picosecond time resolution. • “high” voltage bias applied to SiPms is only 30-70 Volts. • the industrial sensitive size of SiPms is 5x5mm2 is currently available • possible with almost edgeless design, which allows produce different geometry, like matrix, cells in line, etc. Already available on market. • temperature and bias voltage stability requirements defined to keep few ps level. It is not a problem now, especially for TOF application. • good enough radiation stability (J.Freeman data). • lot of company around the globe already involved in SiPm production. 3

4. “Electrical” time resolution. Setups at SiDet Measured value is a time difference between “start” and “stop” signals Thanks to Sten Hansen for the “trombone”. 4

5. SiPms signal must be clipped to fit Ortec 9327 CFD (<5 ns, FWHM) Schematic of SiPm biasing and readout SiPm signal before clipping *** and after, 40 ns scale Same as ***, but 2 ns scale SiPm signal after clipping, few phes. SiPm pulse height spectrum, mean number of photoelectrons = 17 phes. STM, 3.5x3.5mm2, Catania, Italy 5

6. Some examples of what learned at SiDet (SiPms, frontend, DAQ). Time resolution vs MPPC ampl. On 9327 input, two ranges, 100 phes. Time resolution vs number of photoelectrons, 1 V of overvoltage SPTR, IRST SiPm , 1x1mm2, (blue and red light) vs overvoltage SPTR of few MPPC ,1x1mm2 (blue and red light) vs overvoltage 6

7. SETUP IN FERMILAB TEST BEAM Time interval between signals from “start” (SiPm) and “stop” (Photek 240) counters is measured value. Beam is 120 GeV protons. Light is generated in fused silica radiator for SiPm and in the Photek 240 input window with normal particle incidence. beam 7

8. Detectors, frontend, DAQ 8

9. Why SiPms for the fast TOF application? The answer is below Sigma = 16.3 ps MPPC-Photek240 inline The MPPC pulse height spectrum, 120 GeV protons. Radiator 30 mm long, fus silic N of photoelectrons ~ 60 phes Timing difference spectrum for signals coming from Sipm (MPPC) Hamamatsu (radiator is fused silica, 3x3 mm2 and 30 mm long, all surfaces polished) and Photek 240 (radiator is input window, 9.6 mm thick). 120 GeV protons used for the test. Normal incidence. The MPPC time resolution is <15 ps assuming the Photek 240 time resolution is 7.7 ps. Soft pulse height cuts and slewing correction applied. Preliminary. TOF “beamline” measurement performed for the Photek 240 relocated by 7.2 meter downstream from the MPPC, 8GeV momentum. 9

10. Time resolution vs radiator (fused silica) length (3x3mm2 transverse size), normal incidence, March 22-29, 2010 ~60 phes Length of radiator 7mm, 27.5 ps Length of radiator 14mm, 24.5 ps Length of radiator 30 mm, 16.3 ps Timing spectrum, 120 GeV protons. Start – MPPC with fused silica radiator, 3x3mm2 in transverse size, 6 mm in length, all surfaces polished. Stop - Photek 240. Normal incidence. Time resolution is 11.7 channels, or 35 ps/MPPC . June 2009 tb. Corresponding MPPC pulse height spectrum, 15 photoelectrons, June 2009 tb. This result consistent with our previous test beam data. We were not expected the time resolution will be significantly improved (what we see now) with increased radiator length (transverse size 3x3mm2). Need simulation. 10

11. Time-of-Flight (TOF) System with SiPm at MT, FNAL. MT TOF with SiPm. Base distance (B) between start and stop counters 7.2 meters. TOFtime resolution is about 26 ps (sigma) for “light” particles. Slew correction, soft pulse height cut. Analysis continue. Upstream counter, “stop” – Silicon photomultiplier MPPC, Hamamatsu, 3x3 mm2 , 50x50um pixel size, 3600 pixels quartz radiator 30 mm of length, normal particle’s incidence. Best time resolution (sigma) obtained is 14.5 ps per MPPC. Downstream counter “start” - Photek 240, normal to window particle’s incidence, window thickness – 9.6 mm of fused silica. The “inverse” time scale in the right. 8 GeV, 7.2 m of base distance, small peak – protons, high peak corresponds to “light” particle, scale inversed, because upstream MPPC counter used as stop Raw data, w/o any corrections 11

12. Summary • ~26 ps, (sigma), time resolution obtained for MT TOF beamline with start counter based on SiPm coupled with fused silica radiator. Preliminary. • The best time resolution seen in beam conditions for a SiPM is 14.5 ps. • The current systematic error of the data presented for SiPms is about 1 ps. • We have studied timing properties (including SPTR) of several SiPms producers (Hamamatsu, IRST, STMicroelectronics, SensL, Kotura, MePhy, CPTA, etc.). • Requirements to timing of frontend readout electronics were carefully investigated • SiPm’s time resolution dependence on temperature, bias voltage and wavelength well studied now. Requirements to temperature and bias stability defined. • Now we understand much better the phenomena named avalanche development in silicon photomultiplier due to direct contact with producers. • The influence of SiPm structure (e.g. different for Hamamatsu and IRST) on it timing properties investigated by illuminating SiPms with blue (405nm) and red (635nm) light of the PiLas laser head. Simple model proposed to explain the effect. • The last tb SiPm analysis is not completed, continued. • We have a plan for SiPms R&D for nearest future. • Our thanks to SiDet personnel: Hogan Nguyen for long term support of the work, Humberto Gonzalez, Steve Jakubowsky and Nina Ronzhina for technical help. 12