cbm-rich: photodetector developement h8500+nxyter+roc readout
DESCRIPTION
Piotr Koczo ń,GSI. CBM March 2009. CBM-RICH: Photodetector developement H8500+nXyter+ROC readout. P.Koczo ń, R.Karabowicz, R.Lalik, C.Schmidt, V.Kleipe, W.F.J.Müller. H8500+UV LED + nXyter readout Optical properties of pTer – r é sum é Outlook: WLS foils. Piotr Koczo ń,GSI. - PowerPoint PPT PresentationTRANSCRIPT
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CBM-RICH: Photodetector developementH8500+nXyter+ROC readout
P.Koczoń, R.Karabowicz, R.Lalik, C.Schmidt, V.Kleipe, W.F.J.Müller
CBM March 2009 Piotr Koczoń,GSI
H8500+UV LED + nXyter readout Optical properties of pTer – résumé Outlook: WLS foils
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CBM March 2009 Piotr Koczoń,GSI
H8500
HV
PulseGeneratornXyter+ROC
Lighttight box
UV LED
gate signal
20 cm
H8500+nXyter+ROC - setup
Schematic view of themultiparameter measurementof WLS/H8500 properties Aperture mask
with pinholes
ChargeDivider
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CBM March 2009 Piotr Koczoń,GSI
H8500+nXyter+ROC - setup
ChargeDivider nXyter
ROC
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CBM March 2009 Piotr Koczoń,GSI
Charge divider
H8500 multiplication factor ~106 @ 800V biasing voltage but sensitivity
of nXyter input ~ 5 mips (125000 e) => an adapter is necessary!!
The charge divider (details in http://cbm-wiki.gsi.de/cgi-bin/viewauth/Rich/CbmRichMeeting031208 )
is a C/R circuit :PMT N-XYTER
We prepared several boards with different sets of R1, R2, C1, C2:
R1 R2 C2 C1
0 10 k 1 nF 10 pF
91 10 0 nF 2 pF
0 100 1 nF 10 pF
91 10 0 nF 10 pF
0 100 0 nF 10 pF
50 10 k 10 pF 470 pF
(Simone Bianco)
S3
S5
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CBM March 2009 Piotr Koczoń,GSI
Charge divider – 3rd try: not so bad
10 ns
1.6 V
15 ns
40 mV, S5
More advanced simulations by Tim Armbruster Uni HDresult in an attenuation factor of 48.71
Qin
Qout
Qin / Qout = attenuation factor
H.C. Soltveit (one of nXyter developers)claims that it should be possible to trimmthe chip such, that the charge dividerwill be obsolete.
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CBM March 2009 Piotr Koczoń,GSI
H8500 pinhole aperture
Aperture mask
Pin holes
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CBM March 2009 Piotr Koczoń,GSI
System noise
Channel #
Am
plitu
de [
ch]
nXyter has a very sensitive input, it is very noisy.Only by adjusting of global (and channel)offsets and thresholds can be done operational.
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CBM March 2009 Piotr Koczoń,GSI
H8500 signal readoutCh#1 …
… Ch#64Collected charge
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Col
lect
ed c
harg
e
CBM March 2009 Piotr Koczoń,GSI
H8500 – signal readout
Channel #
18 channel# 82 112
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CBM March 2009 Piotr Koczoń,GSI
H8500 readout
82
108
78
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CBM March 2009 Piotr Koczoń,GSI
H8500 readout
H8500 - rear side
Pixelnumber - Channel number - correspondence
112 -> P32
78,82 -> P29, P30
18 -> P4
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CBM March 2009 Piotr Koczoń,GSI
?
H8500 readout
There ist obviously a misaligment betw.the mask and the PM
P4 not understood
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CBM March 2009 Piotr Koczoń,GSI
WLS
Window (1mm)
PM structure
To do 1) H8500 cross-talk – future plans
Hamamatsu claims for H8500: cross talk < 3% (electronics)
WLS can add an additional cross-talk between neighbouring pixels when a photon undergoes absorption-reemision in the WLS layer or falls inclined on the PMs entrance window
Simulations (Paola Solevi, Det.Lab. CERN): σ=3mm(WLS layer)
Inclined photonPhoton transformed in WLS
Propagation in WLS
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CBM March 2009 Piotr Koczoń,GSI
To do 2) Single photon counting capability using H8500+CD+nXyter+ROC
Single photon?
Double hit?
Single Photon Counting capabilityhas been demonstrated (Dubna 2008) in a coincidence measurementwith 2“ Hamamatsu X2020 and Picoscope.
SPC has to be also proved for H8500with nXyter!
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CBM March 2009 Piotr Koczoń,GSI
Ad 2) Single photon counting capability using H8500+CD+nXyter+ROC
Channel #
delta
T[n
s]
Coincidence measurement using nXyter system
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CBM March 2009 Piotr Koczoń,GSI
Conclusions (Part 1)
- nXyter+ROC with CD seem to work with H8500- Further measurements of a) cross talk between pixels with and w/o WLS coating b) single photon counting capability with nXyter system are necessary
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CBM March 2009 Piotr Koczoń,GSI
WLS – summaryP.Koczoń, C.Höhne, A.Braem
C.Joram, M. van Stenis
- choice of the wavelength shifter material- silicon pads with WLS
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CBM March 2009 Piotr Koczoń,GSI
Choice of the WLS material
- Several WLS materials have been tested (TPB, pTerphenyl, YellowX)- Different coating methods (evaporation, spraying)- evaporated p-Terphenyl shows the highest gain- ageing in CO2 not (yet) observed- timing properties not studied
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CBM March 2009 Piotr Koczoń,GSI
Integrated QE of pTer and TPB as function of photon energy
pTerphenyl shows the highest integrated gain
extrapolation
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CBM March 2009 Piotr Koczoń,GSI
WLS embeded in silicon padsWLS - Si pad
PM structure
Window (1mm)
~0.3 mm
Advantages:1) Much easier production as compared to evap. procedure2) Can be prepared in advance in different thicknesses and WLS concentrations3) Can be changed on the PM at any time4) Can be easily exchanged in case of damage5) WLS material protected from chem. influences
? Does it work at all ??? Is thickness an issue ??
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CBM March 2009 Piotr Koczoń,GSI
Thank You !
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CBM March 2009 Piotr Koczoń,GSI
Cross-talks - setup
H8500
HV
PulseGeneratorDAQ
grey filter
Light guide bundle
Lighttight box
LED
gate
signal
XY-table