1. Performance Evaluation of SiPM Arrays under Strong Magnetic Fields
S España1, G Tapias2, L M Fraile1, J L Herraiz1, E Vicente1,3,
J M Udias1, M Desco2, J J Vaquero2
1Grupo de Física Nuclear, Dpto. Física Atómica, Molecular y Nuclear, Universidad Complutense, Madrid, Spain
2Unidad de Medicina y Cirugía Experimental, Hospital General Universitario Gregorio Marañón, Madrid, Spain
3Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain

2. SiPM (G-APD, MPPC, …) have many advantages compared to APD and PMT:
Introduction
SiPM (G-APD, MPPC, …) have many advantages compared to APD and PMT:
High gain
Low Voltage
Fast Timing
Compact size
Low cost
Compatible with magnetic fields

3. Calorimeter Tests of SiPMs
CALICE-HCAL (ILC): CAlorimeter for the Linear Collider Experiment

4. Strong Magnetic Field (7 Tesla)
Goals
Previous results:
SiPMs (1 × 1 mm2)
New results:
2 x 2 SiPM array (6 × 6 mm2)
Strong Magnetic Field (7 Tesla)
1 mm

5. Materials Vendor Active area (mm2) Number of Pixels Pixel size (μm)
PDE (%)
Hamamatsu
(2 × 2 array)
6 × 6
3600/
element 50
Single crystal
Crystal matrix
4 × 4
10 × 10 × 20 mm3 LYSO
1.5 x 1.5 x 12 mm3 LYSO

6. LIM – Hospital Gregorio Marañón
Materials
Bruker BioSpec 70/20 USR
7 Tesla
LIM – Hospital Gregorio Marañón

7. SiPM covers 36% of scintillator base
Experimental Setup
1.- Single crystal
LYSO crystal (10 × 10 × 20 mm3)
SiPM covers 36% of scintillator base
22Na

8. Pulse Shape
NO preamplifier

9. Gain vs Voltage
T=20ºC

10. Gain vs Temperature
Bias = 69.0 V

11. Dynamic Range

12. Energy spectra 22Na
keV = 14%
Bias = 69.0 V
T = 20ºC

13. Experimental Setup 2.- Crystal matrix
4 × 4 LYSO matrix (1.5 × 1.5 × 12 mm3)
18F

14. Flood Field Image
18F
68.2 V - 20ºC
5·105 counts
Software
Anger logic

15. Flood Field Image 18F 68.2 V - 20ºC 5·105 counts Software Anger logic
Peak to valley ratio = 10:1

16. Crystal Energy Spectrum
18F
68.2 V - 20ºC
3·104
counts/crystal

17. Energy Resolution @ 511keV
FWHM (%)
0 Tesla
7 Tesla
Center
11.2
11.9
Center Edge row
14.1
14.4
Corner
21.7
21.4

18. Conclusions
The 2 × 2 SiPM array from Hamamatsu shows very good suitability for its use in the presence of strong magnetic fields.
Monitoring of Temperature and Voltage is needed to correct gain variations.
Combination with LYSO crystals shows potential to obtain energy resolution below 511 keV.
The 4 × 4 crystal array of 1.5 mm pitch size was perfectly resolved with negligible differences at 0 and 7 Tesla.

19. Future SiPMs 1 × 4 channels array 1 × 4 mm2 1 × 1 mm2 / channel