1. Prototype Assemblying, SiPM Characterization and QC
W. Baldini on behalf of the Ferrara SuperB Group
XV SuperB General Meeting, Caltech Dec

2. The IFR Prototype
The Prototype

3. The IFR Prototype The Iron is on Its way to Fermilab Iron
Active Layers
(Pizza Boxes)
The Iron is on Its
way to Fermilab
Iron
Iron: 60x60x92 cm3 , 9 slots for the active layers
8-9 active layers readout together
4 Time readout (TDC-RO) “standard “
4 Binary Readout (BiRo) “standard”
4 special modules to study different
fibers or SiPM geometry

4. Prototype assembling

5. Active Layers: the Pizza Boxes
Pizza box #1: TDC-standard (fibers Bicron-1.0mm, SiPM 1.2x3.2 mm )
Pizza box #2: TDC-standard
Pizza box #3: TDC-standard
Pizza box #4: TDC-standard
Pizza box #5: TDC Special fibers 1.2mm
Pizza box #6: TDC Special round SiPM
Pizza box #7: TDC Special MPPC
Pizza box #8: BiRo Standard (fibers Kuraray 1.2mm, SiPM 1.4x3.8 mm )
Pizza box #9: BiRo Standard
Pizza box #10: BiRo Standard
Pizza box #11: BiRo Standard
Pizza box #12: BiRo Special Round SiPM
Menu’

6. Pizza boxes Assembling Prepare the supports and place
the scintillator bars
Pizza boxes
Assembling
fibers positioning
Put silicone Sealant
to fix fibers and keep optical glue inside the embedded holes

7. Labeling and collecting
the fibers around the supports
Fill the machined grooves
with optical grease and cover
it with stripes of reflecting
aluminum (BiRo only)
Fill with optical glue
the embedded holes
Put double-side adhesive
to fix the second layer
(BiRo only)

8. Aluminum tape
Aluminum on the
not-readout end of
the fibers
Positioning of the second
layer of scintillators (BiRo)
Sputtering
(on 1 pizza box)

9. Fiber-SiPM coupling
Fibers
SiPM
Output Connector

10. Local test with cosmics
All the active layers have been assembles ad locally tested with cosmics
The test was very fast (not much time left before the shipping to Fermilab)
We performed a rate vs Threshold scan, from 4.5 p.e. up to 10.5 p.e. for each channel of the pizza box, looking for a “plateau” around the expected cosmic rate: ≈ 2Hz
This test was basically done to check the functioning of the SiPM and could not give any efficiency or time resolution estimate
This parameters are being measured thanks to the testbeam data

11. Local test with cosmics Rate (Hz) Rate (Hz) Vbias
Pizza Box Channel
Rate (Hz)
Vbias
Roughly the expected rate
Pizza Box Channel
Thr (p.e.)

12. SiPM Characterization

13. SiPM Characterization
three types of SiPM tested:
1.2x3.2 mm2 (type 4020), to be coupled to 1.0mm fibers (3 fibers), total 126 needed, 171 characterized
1.4x3.8 mm2 (type 4380), for 1.2mm fibers, 128 needed, 172 characterized
array of 3 round sensors: f=1.4mm, for both 1.0mm and 1.2 mm fibers, 53 needed, 94 characterized

14. SiPM Characterization summary
Received and tested 437 SiPM:
x3.2 mm2 (4020) :
Good: 160
Bad: (no signal)
Yield: 93.6%
x3.8 mm2 (4380)
Good: 166
Bad:
Yield: 96.5%
94 round F=1.4 mm (5550)
Good: 84
Bad: 10
Yield: 89.4%

15. SiPM Selection

16. SiPM Selection Custom software (Labview) has been developed
Acquires noise distributions (tipically events )
Fit distributions with 2 gaussians (1 p.e., 2 p.e) and calculate G
Plot/fit G vs Vbias and 0.5 p.e. threshold vs Vbias

17. For each SiPM we measure 4 paramenters:
mG, qG G vs Vbias linear fit parameters
mth, qth Thr(0.5p.e) vs Vbias linear fit parameters
From the above parameters we calculate the working Vbias voltage for a chosen Gain:
G = mG* Vbias + qG  Vbias = (G-qG)/mG
and the corresponding thresholds:
0.5p.e. = mth*Vbias + qth
Th (n*p.e.) = Th(0.5p.e.) + n * G
with the above paramenters we can set each SiPM at the desired working point (Gain, Thr)
Since we equalize the Gain, the dark count could be very different from each other

18. 1 p.e.
2 p.e. G
Noise Spectra
We measure Gain and Dark Count Rate vs Vbias and select the most homogeneous devices for each type
0.5 p.e.
G vs Vbias

19. SiPM Selection Dark Count (Hz) Vbias=33V, th=2.5 p.e. Spares Selected
G>15 mV/p.e.
Spares
DC< 200 KHz
Selected
Gain (V/p.e.)

20. Parameters comparison
Vbias = 33.0V , Thr = 2.5 p.e.
Ratio DC/G among the three types:
4020: <DC/G> = 4.1 x 106 Hz*p.e./mV
4380: <DC/G> = 5.9 x 106 Hz*p.e./mV
5550: <DC/G> = 6.6 x 106 Hz*p.e./mV
Ratio DC/Area:
4020: x 104 Hz/mm2 (area = 3.84 mm2 )
4380: x 104 Hz/mm2 (area = 5.32 mm2 )
5550: x 104 Hz/mm2 (area = 4.62 mm2)

21. Conclusions
The assembly of the 12 active layers was completed on Nov 3-rd
The local cosmics tests were completed on Nov 8-th (the shipping was foreseen on Nov 9-th…)
Not enough time to perform extensive tests before the testbeam...
First “impressions” from testbeam were encouraging (online monitor showed a good behaviour)
Efficiency and time resolution studies are ongoing with testbeam data