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Development of scintillation detectors with MRS APD light readout for CBM Muon
system and ECAL preshower
Alexander AkindinovITEP(Moscow) on behalf of
ALICE-ITEP group
Outlook
• MRS APD – fast Geiger mode high gain photodetector
• START – technology• ALICE CRTF – first implementation for START
technology• Counters for CBM muon systems• Counters for EMCAL preshower• Conclusion
MRS APD – fast Geiger mode high gain photodetector
-Voper
Readout
MRS APD structure
47 48 49 50 51 52 53U , VAPDg
U
2
4
3
5
6
7
Gai
n in
one
cel
l,
+
105
Gain 6.6.105
Q
Cone cell
<Q>one cell
U
1200
1000
800
600
400
200
025 50 75 100 125 150 175 200 225 250
Entries 1019173e
4e
5e
6e
7e
ADC channels
pede
stal
1e
2e
Single electron resolution is a result of dispersion of Ubr and Ccell across diode area.
Slope corresponds to elementary micro-cell capacity Q/U.
M = C*(U - Ubr)
Q = Ncell*C*(U - Ubr)
Many other name:SiPM, MPPC, GAPD…
Optical trench(CPTA) – low optical coupling between cells.Acceptable noise rate for reasonable thresholds
0 10 20 30 40 50 60 70101
102
103
104
105
106
3 cells
2 cells
1 cell Noise spectrum
Noi
se c
ount
, Hz
U thr ,mv
Noise spectrum slope is a result of “red” cross-talks between cells, when avalanche in one cell initiate avalanche in neighboring one via photon.
Probability to have more than one pixel fired from a single primary e-h pair = (N n+1)/ (N n )
CPTA MRS APD α= 0.1 For 4th cell threshold noise count about a few kHzHigh geometrical factor
PDE is optimize for WLS fibers
P.D.E. = Q.E. * g* R εg – geometrical fill-factorR – probability to initiate Geiger avalancheQ.E. – quantum efficiency
START- (Scintillation Tile with MRS APD Light ReadouT)
Two MRS APD in coincidence
σ-shape groove for uniform response
“On board” FEE
Mosaic array
MRS APD optimize geometry (d=1.15 mm) for the fiber readout
Polisterol 165 150X150X10 mm1 groove, 2 rings Y11 and glued
Threshold
0 20 40 60 80 100 120 140
10-4
10-3
10-2
10-1
100
101
102
103
104
105
106
Coincidence F1 * F2 * 100 ns (250 ns delay for Dn2)
Count ,
Hz
Threshold , mV
Cosmic μ
Signal/noise
First implementation - ALICE CRTF
Inner trigger counters
Outer trigger counters
TOF modules
Frame
Up to 5 ALICE TOF modules under the test.
Bottom plane10 strips 8 STARTs
in each (80 STARTS)
Upper plane10 strips 8
STARTs in each (80 STARTS)
Trigger and monitoring
•!!Monitoring the only by counting rate of individual detector, no any LED system was used.!!!•Efficiency was measured as difference in counting rate for 80 pairs.
Simple logic block for trigger configuration and monitoring were connected via USB to LabView
Long term operation results
Reason Number of diodes
Explanation Action
Leakage current increasing up to 20 μA
27 Bad insulation between metal and cell for trench technology
Informing CPTA, work in progress
Zero current 4 Bad bonding Negligible, but informing
CPTA
Total: 31 !!!!<10 % for 3 years continuos operation!!!!!
First real experiment with 320 new photosensors (CPTA firm MRS APD). About 3 years of continues operation, all 87 ALICE TOF modules was tested.
Summary of “dead” and replaced diodes
Counters for CBM muon system
INTAS Ref. Nr 06-1000012-8781“Develop and produce START prototypes adapted for dE/dx measurements. Five detectors of each of two types of START will be produced: tiles sized 100x100x 10 mm3 and strips sized 5x200x10 mm3
Tiles with different groove diameters to find optimal uniformity (d = 90, 80, 70, 60, 50 mm)
Strips 5x200x10 mm3
ROLAND milling machine!!!Many thanks to our friends from ITEP-CALICE group!!!!
New package to minimize “dead zone” and new connector
New transparent optical connector produced by the same digital milling machine as tiles
Very uniform response (about 8%). Main sources - regions near optical connectors and groove.
TO-18 New package
Diodes calibration and fiber cut
Setup to cut fiber with microscope
Each diode after placement into connector was checked (how well diode active area is with connector hole)
Mixer
12 channel board
Setup for diodes test
Diodes calibration and fiber cut
18 19 20 21 22 23 240
1
2
3
4
5
6
7
8
9
10
11
12
4 Volts overvoltage
D1 D10
I , u
A
U , V
I-U curve to find out breakdown point Number of photoelectrons for given light was checked
Single cell noise and photoionization (α) coefficient were measured
Detector assembly and electronics
FEE card for tiles
Simple amplifier for strips (10mm width)
Tiles were wrapped in Tyveсk and light shield
GND +4-+10 VLVDS
Amplitude 1(50 Ω)
Jumper 1 for coincidence(on)
Jumper 2 for coincidence(on)
Threshold
Ubias
Ubias сontrolTest input (50 Ω)Jumper 2 for test
LED
FEE for tiles
Amplitude 2(50 Ω)
Jumper 1 for test
First task: find optimal geometry for uniform response
D=50 mm
D=60 mm
D=70 mm
D=80 mm
D=90 mm
D 50 60 70 80 90
R.M.S 10.1 8.7 6.6 4.7 5.8
-60 -40 -20 0 20 40 600,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
Ampl
itude
, a. u
.
y, mm-60 -40 -20 0 20 40 60
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
Ampl
itude
, a. u
.
y, mm
-60 -40 -20 0 20 40 600,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
Ampl
itude
, a. u
.
y, mm
Scans were done using Ru β – source with 2.5 mm collimator. 19x19 points (5 mm step).
New improved MRS APD (2007)
Data was taken from http://www.photonique.ch/Photonique SA C.P. 15621211 Geneva-1Switzerland
2005 – diodes for ALICE CRTF
New diodes 2007
Reduced thickness of n+ - PDE increased + blue enhanced
Light yield with old and new diodes
“43V” old “23V”new
N ≈16 ph.e.
Tile 150x150x10 mm3
N ≈ 29 ph.e.N ≈ 22 ph.e.
“23V”new
Tile 100x100x10 mm3
Beam test CERN PS (2x2 cm2 trigger center of tile)
With this significant improvement can we work with one diode?
Tiles with single diodes
So called “half-board” designed for long strips
100x100x10 mm3 with one output for fiber ( d=80 mm )
Three reasons to produce tiles with one diode:1.To check if we can improve light yield using another glue2.Check if we can work with one diode3.Make prototype for ECAL preshower
3 tiles were used for test2 were assembled for cosmic test
Other task: to improve gluing
Not glued
Bicron optical cement
Mono-component optical glue (UV light polymerized)
Epo-Tek 301
1 1.58 1.41 1.68
How it’s important
Does not depend on plastic type
Measurements were done before and after gluing with the same diode
4 grams each timeAccuracy up to 0.01g
Since refractive indexes almost the same we can suppose that difference is due to acid type (groove walls “melting” – more uniform and transparent volume). For our milling process – Epo-Tek 301 is the best.
Cosmic ray test one diode
50 100 150 20010-1
100
101
102
103
104
counts
Cou
nts,
Hz
Threshold, mV
It works!!! We can use only one diode.
Diode noise
“Soft” and “hard” part of cosmic ray
“Soft”
Muons
MuonsPed
Last task: Strips
4 stripes shows some “oscillating” signals. Reason bad 3M mirror contact. All tiles were reassembled. New test will be done about 20 of October.
3M tape
R.M.S ≈ 12%
Conclusion• START detector was adopted for dE/dx measurements• Optimal diameter d=80 mm for tile 100x100x10 mm3
response was found (r.m.s < 5.0 %).• EPO-TEK 301 glue was found as optimal to increase light
yield.• 3 types of FEE board were produced (all commercially
evaluable)• Progress in MRS APD development allows to use only one
diode for readout keeping signal/noise ratio almost the same like for two old diodes
• 4 strips 200x10x5 mm3 were reassembled and will be tested again. Good one has 12% r.m.s.(?)
• Tools for mass production were produced.
Thank you!
BACKUP
MRS APD calibration Ubias for given amplification about 106
Thank to Yuri Musienkofrom CMS APD lab.
Response and leakage tests
All current is due to intrinsic noise, no significant leakage
2
...
SMR
PQN
Difference – small difference in α and coupling with fiber (epoxy layer share)
Noise measurements
Photoionization αDifference – different field noise contribution to the thermal noise
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C800.1
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R82510
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C20
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C1300.1
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R61 1k5
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C32 1p1 2
C21 22n1 2
C61 22n1 2
U22 MAX961
4 56781
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LE GNDQQ
VccIN+IN-SHDN
R50510
12
JP21JP
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3V3
JP20JP
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3V3
R11010
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R31100
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R70150k
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C90 0.11 2
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JP12 APD21 2
R10 51k1 2
R51510
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C520.1 1
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R2051
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C50
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C60
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C100 0.11 2
R32100
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IN+
C31 1p1 2
C10
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D10BAS16
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R62 1k5
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R52510
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45
6
7
8 1
23
9
10
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FREQGND
Vcc
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C720.1
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JP10 JP1 2
R102510
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U50 LMC555
4 56781
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RESET CtrlThresh
DischV+GND
TROUT
R911k
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R801k
R60 1R12
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2
3
C92
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3V3
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C4110u
C1222n
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R100 100k1 2
C1122n
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C30 10n
12
R101510
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JP31 JP12
U40
DS90LV011A
1
52
43
Vdd
TTL INGND
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2
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3V3
R301k
R90 1501 2
R41510
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L10100uH
C62 22n1 2
R11 100k1 2
C82 100p
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R81510
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R7251
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