Pisa activities II part

1. Pisa activities II part Maria GiuseppinaBisogni Universita’ di Pisa and INFN Sezionedi Pisa

2. Outline • SiPM 4x4 matrices new results • 8x8 matrices first results • New DAQ system

3. SiPM Matrices and arrays readout • Framework: development of a SiPM based PET system demonstrator based on • Matrices of SiPM pixels (FBK-irst) • Final target  8 x 8 ; Currently available  4 x 4 • Front-End ASIC with trigger and digitization capabilities (Politecnico di Bari) • Final target  32 channel ; Currently available  8 channel • Meanwhile, readout of SiPM matrices employing different systems: • Readout system from LAL-Orsay (MAROC2 ASIC). • Readout system for PET applications employing the VA-TA ASICs from gamma medica-IDEAS (SiPM0)

4. 1 mm 4 mm SiPM 4x4 matrices from FBK-irst Composed of 16 (4x4) pixel elements in a common substrate 1 mm pixels in 1.06 mm pitch • Structure: n+-p-p -p+ optimized for blue light: Shallow n+ layer + specific antireflective coating. • Each pixel: 625 (25 x 25) microcells, 40mm x 40mm size. • Polysilicon quenching resistor. • Fill factor 44%. Bonded SiPM array SiPM array SiPM pixel

5. 4x4 Matrices Characterization • Full characterization of first run performed at LAL, Orsay. • Excellent uniformity. • Breakdown voltage 30.5V ; svar= 0.5% • Gain @33V 1.46x106; svar= 4% • Mean dark rate @33V (DV=2.5V): 1.98 MHz • PDE @ 33V 8-10% from 420 to 680 nm wavelength. Expected PDE >15% for the results shown here (run II and DV=4V) N. Dinu et al. Pixel 2008 workshop, Fermilab, September 2008.

6. Readout: MAROC2 ASIC • Developed at Laboratoire de l'Accelerateur Lineaire, Orsay. • 64 channels • low noise preamplifier w variable gain (6 bits) • Slow shaper (~20-150 ns, adjustable) • Fast shaper (15 ns) + 3 discriminators =>Trigger signal. • Designed for MAPMT – not optimized for SiPMs, but allows us to make the tests satisfactorily.

7. Readout: Test board • Altera FPGA • USB Port • ADC on the board. • ASIC calibration input. • LabVIEW software for data acquisition

8. Experimental Results • Results with pixilated crystals • Results matrix + crystal array • Results with continuous crystals • Results matrix + slab • Position determination • G. Llosa et al., IEEE- MIC2008, paper M02-1 • Submitted to TNS on march 23

9. Position determination • Coincidence with a 2nd detector: 1 mm x 1 mm x 1 mm crystal coupled to a SiPM • Source close to the matrix, far from 2nd detector • Move together source and 2nd detector. 2nd detector 30 mm 2 mm

10. Position determination setup

11. Position determination- crystal array + 1 mm + 2 mm Hitmap for different source positions with crystal array + 0.5 mm + 1.5 mm

12. Position determination-black slab • Matrix + LYSO crystal 4mmx4mmx5mm painted black • Center of gravity algorithm – problems at the edges • Difficulties due to the small size of the devices

13. Position determination-black slab • Hitmap • Algoritmo “center of gravity”

14. Edge distortions

16. Statistics • 12 wafers. Alcune di questi hanno un leakage alto, sintomo di dark count alto. • Ogni fetta contiene 12 matrici con read-out da un lato e 4 matrici con read-out da entrambe i lati • matrici con read-out da un lato: • 32 matrici con tutti elementi funzionanti • 22 con 1 elemento su 64 non funzionante • 8 con 2 elementi su 64 non funzionanti • matrici con read-out da 2 lati: • 10 matrici con tutti elementi funzionanti • 8 con 1 elemento su 64 non funzionante • 3 con 2 elementi su 64 non funzionanti • Wafers 9,10,11 a Perugia per IV test dopo il taglio • Wafers 12, 14, 15 a Pisa • Wafer 14: 16 linear array 1x8

17. Wafer 12 C4 all chns working

18. Matrix 8x8 first Na22 coincidence spectrum

19. DASIPM3 new set-up Designer A. Soldani Servizio Progettazione Meccanica INFN Pisa

20. New DAQ System B side 64 chns A side 64 chns Conceptual Design from Ing. Giovanni Franchi from AGE Scientific