Author: popov

IEEE NUCLEAR SCIENCE SYMPOSIUM & MEDICAL IMAGING CONFERENCE San Diego, California, USA
31 October - 7 November 2015

Time characteristics of silicon photomultipliers used in the GlueX experiment
Fernando Barbosa1, Alexander Somov1*, Sergey Somov2, Ivan Tolstukhin2
1Thomas Jefferson National Accelerator facility, Newport News, VA, USA
2National Research Nuclear University MEPhI, Moscow, Russia

Abstract
The GlueX detector in Hall D at Jefferson Lab is instrumented with about 5000 Silicon Photomultipliers (SiPM) manufactured by Hamamatsu Corporation.
Silicon photomultipliers with a sensitive area of 3x3 mm2 are used to detect light from scintillator detectors such as the tagger microscope, pair spectrometer, and start counter. An array of 4x4 SiPM sensors was specially designed by Hamamatsu for the instrumentation of the barrel electromagnetic calorimeter. SiPMs in the tagger microscope and start counter will be operated at a relatively large rate of up to 2 MHz. We performed measurements of the time resolution for different SiPM operation rates and estimated the SiPM pixel recovery time. Time characteristics were compared for sensors with two pixel sizes: 25 μm (MPPC S10362-33-025C, S10931-025P) and 50 μm (MPPC S10362-33-050C, S10931-050P). Time resolution of the SiPM array (MPPC S12045) was measured as a function of light intensity for several SiPM temperatures. Studies were performed using a picoseconds laser light pulser and a light-emitting diode.

Hamamatsu MPPC S10931
- effective area 3 mm x 3 mm
- surface mount

Start Counter

Readout board
with SiPMs

30 scintillator paddles around the GlueX target
Measure time of charged tracks

4 SiPMs per paddle

Scintillator paddle

Beam

Tagger Microscope

Array of 102 x 5 scintillator
fibers
Detect electrons, measure time

Pair Spectrometer

SiPM mounting plate

Array of 145 scintillator tiles
(2 detector arms)
Detect e± pairs

WLS fibers

Scint. tiles

Barrel Electromagnetic Calorimeter

Hamamatsu MPPC S12045
- array of 16 3 mm x 3 mm SiPMs
with the pixel size of 50 mm
- 16 cells connected in parallel

3 mm2 SiPM

BCAL module

48 modules (Pb:Scint) read out from two sides
3840 SiPM arrays
with the pixel size of 50 mm

Light
guides

GlueX specifications:

Detector	SiPM / Type	# sensors	Light yield (pixels)	Rate(MHz)	st design (ps)	st meas (ps)
Start Counter		120	60 - 120	< 0.2	< 300	300
Tagger Microscope	S10931-050P	510	200	1 – 2	< 300	220
Pair Spectrometer		290	60 - 100	< 0.02
Barrel Calorimeter	S12045	3840			400 (1500 pix.)

	Pixel size / (mm)	Number of / pixels	Fill factor / (%)	Gain (105)	Typical break down (V)
S10931 - 025P	25	14400	30.8	2.75	69.1
S10931 - 050P	50	3600	61.5	7.5	70.5

SiPMs with a pixel size of 25 mm (S10931 - 025P) have about a factor of 2 smaller photon detection efficiency due to the smaller fill factor

Compare performance of SiPMs with the pixel size of 25 mm and 50 mm
in order to decide which to use in GlueX

Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

SiPM Recovery Time

Setup for SiPM timing measurements

SiPMs

diffuser

LEDs

PLP-10 laser

S10931 - 025P ( 25 mm)

S10931 - 050P ( 50 mm)

LED pulses (top)
SiPM signal (bottom)

LED 1

LED 2

Programmable
delay

SiPM pulse

Use two blue light-emitting diods
High intensity light flash from the first LED
Measure SiPM amplitude from the second LED for different delays between the two flashes

SiPM amplitude induced by the second LED as a function of the flash delay

SiPM amplitude induced by the second LED as a function of the flash delay

Typical SiPM recovery rime: t = 18 - 20 ns for S10931 - 025P ( 25 mm pixel size)
t = 35 - 40 ns for S10931 - 050P ( 50 mm pixel size)

SiPM Timing Measurement

Compare time resolutions for the SiPM array (S12045) and 3 mm2 SiPMs with the pixel size of 25 mm (S10931-025P) and 50 mm (S10931-050P)
- measure resolution of the array (S12045) at different temperatures
Estimate time resolution by measuring time difference between two SiPMs
Use Hamamtsu PLP-10 laser with a pulse width of 70 ps and the wavelength of 405 nm.
- good laser light yield stability up to at least 10 MHz rate
Use fast blue LED driven by a pulse generator ( HP 8116 ) to simulate scintillator response. Rise time of the light pulse ~ 3ns (pulse width 8 ns)
Electronics: discriminator CFD Ortex 935, Caen VX 1290 25-ps TDC, 12-bit flash ADC. Use Canberra 2145 time-to-amplitude converter for timing measurements of the SiPM array
Typical SiPM operation voltage 1 V over breakdown
SiPM laser pulse shape
S10931 S12045
Rise time (ns) 5 (1.5 intrinsic amplifier) 6 (4.5)
Pulse width FWHM (ns) 16 60

LED

S10931 - 050P ( 50 mm)

Time resolution as function of the number of fired pixels

Laser

Laser

S10931

Array S12045

Electronics resolution

Electronics resolution

SiPM Performance at High Rate
All PMT and active base assemblies were studied using a PLP-10 [3], Hamamatsu laser light source which provides about 60 ps width light pulses at an adjustable repetition rate. The source intensity was calibrated using the single photoelectron peak to ensure that the tubes were tested with sufficient photoelectrons to simulate conditions close to the desired photomultiplier operating condition (200 to 300 pe).
A sample histogram of the single photoelectron pulse height distribution obtained with the R9800 tube connected to the active base and PLP-10 light pulser.

S10931 - 025P ( 25 mm)

S10931 - 050P ( 50 mm)

Max. rate in GlueX

Max. rate in GlueX

Time resolution as a function of the laser pulser rate

Time resolution as a function of the laser pulser rate

Summary
Time characteristics were compared for the SiPM array (MPPC S12045) and SiPMs with two pixel sizes: 25 μm (MPPC S10931-025P) and 50 μm (S10931-050P). 50P). Time resolution of the 25 μm SiPMs were found to be slightly worse than that obtained for 50 μm sensors. 25 μm SiPMs also have about a factor of two smaller photon detection efficiency. The resolution of the array was found to be a factor of two worse than that of the 3x3 mm2 sensors. The array has a substantially higher noise level, which can account for some temperature dependence of the time resolution in the region with a fewer number of fired pixels. The typical SiPM recovery time was measured to be t = 18 - 20 ns and t = 35 - 40 ns for the 25 μm and 50 μm sensors, respectively. No degradation of the time resolution was observed up to the SiPM rate of at least 2 MHz, which is the expected maximum operating rate of SiPMs in GlueX. The 50 μm MPPC S10931-050P was chosen for the instrumentation of the GlueX start counter, the tagger microscope, and the pair spectrometer.