CALICE Meeting DESY 14.02.07 ITEP&MEPhI status report on tile production and R&D activities Michael...
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Transcript of CALICE Meeting DESY 14.02.07 ITEP&MEPhI status report on tile production and R&D activities Michael...
CALICE MeetingDESY 14.02.07
ITEP&MEPhI status report ontile production and R&D activities
Michael Danilov ITEP
Status of tile production
Tiles for 32 cassettes have been delivered to DESY
Tiles for cassette # 33 are ready
We have good SiPM’s for 3 more cassettes
Delivery of SiPM’s is going smoothly
We expect all 38 cassettes ready for delivery by the end of March
Tiles with WLS fiber
3 mm thick tile with diagonal fiber
3mm thick tile with arch fiber
Standard 5 mm thick tile with arch fiber
Uniformity is good enough and photo-electron yield is sufficient even for 3mm thick tiles
Vertical scale is shown for 1.5MIP
Tile thickness reduction can save a lot of money (~?/mm) or increase HCAL thicknessHowever the effect on the energy resolution (sampling fluctuations) should be estimated
CALICE main meeting, CERN, September 20-22, 2006 M.Danilov ITEP,Moscow
Direct SiPM coupling- desirable to simplify production, but …
Tile 30x30x5 mm3
SiPM
SiPM calibration
CALICE main meeting, CERN, September 20-22, 2006 M.Danilov ITEP,Moscow
Tile 30x30x5 mm3
SiPM on top of a tile
SiPM calibration
Uniformity measurements of 30x30x3mm3 tiles at ITEP synchrotron Arch Fiber&SiPM, 1.5MIP
Uniformity is even worse for 3 mm tiles
Light yield is sufficient for 3mm thick tiles with glued WLSF and SiPM (~15pix./MIP) and larger area SiPMs (3x3mm2) or MRS APD (2x2mm2 blue extended) but noise is too high in these detectors to resolve individual p.e. – bad for calibration
Problems with direct coupling will be more severe for larger size tiles
Direct coupling of 2x2mm2 blue MRS APD
MIP signal for 3x3mm2 SiPM
T241, t2, u=21.2 V
0
50
100
150
200
250
300
350
400
0 50 100 150 200 250 300
ch
N
SiPM
Tile
3M
Plastic scintillator 30x30x5 mm3 without WLS fiber and 3x3 mm2 SiPM assembly was tested at MEPhI (room temperature) with Sr90
Optical glue
Sr90
SiPM- tile assembly
Efficiency of light registration appr18%
Appr. 30 fired pixels/MIP
signal(x)
0
10
20
30
40
50
60
70
80
90
100
-15 -10 -5 0 5 10 15
x, mmsig
nal, a
.u.
Noise probability & Light Collection Uniformityfor 3x3 mm2 SiPM-tile assembly
3*10-5 * 8000=0,24 events/prototype
21.2 V, strob 100 ns
0.0000001
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
porog, MIP
w(>p
orog
)
Threshold, MIP
Noi
se p
roba
bili
ty
abov
e th
resh
old
Absence of individual p.e. peaks is a serious drawback for calibration
Photo-electron yield for direct MPPC coupling to 30x30 mm^2 tiles
5 mm thick tile, MPPC at side center 3 mm thick tile, MPPC at side center
Gluing increases photo-electron yield for 5 mm thick tiles
Photo-electron yield is too small for 60x60 mm^2 tiles (~2p.e. without gluing)
MPPC in tile corner Glued MPPC in tile corner
350 400 450 500 550 600 650 700
0
5
10
15
20
25
PD
effi
cien
cy ,
%
Wavelength , nm
MPPC Studies
0,0 0,5 1,0 1,5 2,00
10
20 370 405 470 565 595 660
Effi
cien
cy ,
%
Overvoltage U, V
PDE agrees well with the MPPC specification
ΔU=1.7V
-10 0 10 20 30
1x104
2x104
3x104
4x104
5x104
6x104
Hz (du=1,7V) ExpGro1 fit of f1etemp_f1e
Dar
k ra
te, H
z
Temperature C
overvoltage = 1,7 V
-10 0 10 20 3073,5
74,0
74,5
75,0
75,5
76,0
76,5
Bre
akd
own
volta
ge
Ubd
, V
Temperature C
-10 0 10 20 30 40 50-0,035
-0,030
-0,025
-0,020
-0,015
-0,010
-0,005
0,000
0,005
Data: Data4_BModel: ExpDec1 Equation: y = A1*exp(-x/t1) + y0 Weighting:y No weighting Chi^2/DoF = 1.1526E-7R^2 = 0.98635 y0 0.00044 ±0.00011A1 -0.02541 ±0.00072t1 7.83714 ±0.25206
Am
plitu
de, a
.u.
time, ns
B ExpDec1 fit of Data4_B
MPPC fast decay time indicates small R and fast recovery time
This leads to double signals from one pixel during a long pulse
LED pulse 28ns
Measurements at DESY and ITEP give 7-9 p.e./MIP for direct MPPC (1600pix)readout of 5mm thick 30x30mm2 tiles and ~5p.e./MIP for 3mm thick tile
MPPC do not provide enough p.e. for direct readout of 3x30x30mm tilesPhoto-electron yield is even smaller for larger tiles (~2p.e. for 60x60x5mm3 tile)
Larger size MPPC can be adequate for direct tile readout since noise is not a limiting factorHowever long term stability and radiation hardness should be demonstrated
MPPC saturation curve dependence on pulse length create problems for calibration
MPPC 28 and 37nsLED pulses
SiPM, R~28 and 37nsLED pulses
Radiation damage measurements
ITEP SynchrotronProtons E=200MeV(preliminary)
Dark current increases linearly with flux Φ as in other Si devices:
Δ I=α Φ Veff Gain, where α=6x10-17A /cm
Veff ~ 0.004mm3 determined from observed ΔI looks a bit too high (since it includes SiPM efficiency)but not completely unreasonable
Since initial SiPM resolution of ~0.15 p.e. is muchbetter than in other Si detectors it suffers sooner:After Φ~1010 individual p.e. signals are smeared out
However MIP signal are seen even after Φ~1011/cm2
At ILC neutron flux is much smaller than 1010/cm2
except a small area (R<50cm) around beam pipe
→ Radiation hardness of SiPM is sufficient for HCAL
Comparison of different Multipixel Geiger Photo Diods (MGPD)
MGPD were illuminated withY11 (green) and scintillator (blue) light
Efficiency was normalizedto MPPC one
.
Noi
se
freq
uenc
y
Scintillator strips with WLSF and SiPM readout can be used for ILC muon system
Cosmics
N pixels =20
Tests of 2 m long strip at ITEP
Position along strip can be determined from time measurements: ΔT~2ns leads to ΔX~25cm(ΔT~2ns was already achieved)
Conclusions
Scintillator tile calorimeter with WLSF and SiPM readout is a viable option for ILC HCAL but industrialization is needed for several hundred times larger system
Thin scint. strips with WLSF+SiPM readoutprovide sufficient light and uniformity (~6%)for last layers of EM calorimeter(approach tested extensively by Japanese groups)
Uniformity measurements for 3x10x45 mm3 strip with WLSF and SiPM readout
Summary
ILC HCAL prototype is the first (and successful!) large scale (~104) applicationof novel photo-detectors – SiPMsAmong 4536 channels in cassettes 3-23 only 1.1% are dead (soldering problems)and 1.1% show long discharges (reason for long discharges was understood, will be fixed in next SiPM version)Within errors situation is stable in time
Scintillator tile calorimeter with WLSF and SiPM readout is a viable option for ILCfor analog and semi-digital approaches, but a lot of industrialization is requiredThe same technique can be used for ILC muon system and last layers of ECAL
Possibility to use direct MGPD coupling is still to be demonstrated(uniformity and p.e. yield)
The field is developing very fast. Photo-detector properties improve every year.The final choice of the Photo-detector depends on the overall optimization
Selection between Analog, Digital or Semi-Digital approaches depends on the outcome of the test program at CERN and FNAL