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Mark Raymond - [email protected] - 16/11/05 1
Trip-t testing
progress report modifications to test setup - hardware and software SiPM pulse height spectra linearity measurements discriminator measurements
Mark Raymond - [email protected] - 16/11/05 2
Test set-up
Trip-t
ProgrammableDigital PatternGenerator
~12 control linespreamp int./resetpipeline, multiplexer,programming
Qinj
ADC
Scope
LabVIEW
VMEck and trig.
level shiftdECL ->
2.5V CMOS
ADC now integrated intosystem – software writtento perform automatedlinearity measurements(using prog. attenuator)and get SiPM pulse heightspectra
prog.attenuator
Mark Raymond - [email protected] - 16/11/05 3
SiPM connection
connection method Vbias
1 M
50
thin coax
SiPMLED
trip-t
3p3
82p
short length (~15 cm) coax between SiPM and tript (at the moment)SiPM connected between core and coax sheath (core carries bias voltage)50 provides some kind of termination for the cablecharge split between two tript channels using different capacitor values to get high/low gain
would need to feed in smallcurrent here to tune Vbias for
individual SiPM’s
Mark Raymond - [email protected] - 16/11/05 4
SiPM/tript results
single p.e. spectra (200,000 events)
1500
1000
500
0
sign
al c
ount
s
10.0x103
9.59.08.5
ADC units
60x103
40
20
0
noise
counts
R1 (0509-023)39.0 V bias11/11/05
led noise only
Russian SiPM (CPTA – 600 pixels)
led pulsed (20 ns) duringpreamp integrate period(red distribution)
preamp integrate:reset ratio 350ns:50ns
get blue distribution when ledswitched off (~ 1 or 2 p.e.)
Mark Raymond - [email protected] - 16/11/05 5
SiPM/tript results – signal vs led pulse amplitude
600
500
400
300
200
100
0
coun
ts
11.0x103 10.510.09.59.08.5
ADC units
5000
4000
3000
2000
1000
0
coun
ts
11.0x103 10.510.09.59.08.5
ADC units
50004000300020001000
0
8600858085608540852085008480
expand
increasing led pulse amplitude high gainchannel
low gainchannel
limit ofhigh chan.
linear range(~ 2 pC inthis case)
led saturating?
single p.e.spectrumvisible
~ 25 pC
each distribution showsthe spectrum obtainedfor a fixed led pulseamplitude
Mark Raymond - [email protected] - 16/11/05 6
linearity studies
12.0x103
11.5
11.0
10.5
10.0
9.5
9.0
8.5
AD
C u
nits
2520151050
charge injected [pC]
~ linearrange
high gain channel
low gain channel
test charge injected viaprogrammable attenuator
different curves for differentvalues of tript discriminatorthreshold voltage Vth.
linearity not expected to bethat good for this version ofthe chip (see Fermilab tripttest docs.)
discontinuities occur wheresignal crosses Vth - could bedue to crosstalk on chip ortest board
needs further study – may need careful strategy tocalibrate out in system
~ 2 pC
discontinuities occur atdifferent points depending
on programmed disc.threshold setting
Mark Raymond - [email protected] - 16/11/05 7
discriminator timing studies – early result1
V /
div
.
5 ns / div.
charge injection edge
tript discriminator output
td
discriminators outputs constantly enabled so appear immediatelyat chip O/P when they fire
measure td (scope)for many triggersfor different signal sizes
note: td also includes fixed cable delays
Mark Raymond - [email protected] - 16/11/05 8
discriminator timing studies – early result
600
500
400
300
200
100
0
cou
nts
5045403530td [nsec.] 44
42
40
38
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34
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28
td [
nse
c]
6005004003002001000Qin [fC]
distributions show value of td (delay between charge injection edgeand disc. firing) for different values of charge, but for fixed value ofdiscriminator threshold setting
take distribution mean values andplot dependence on QinQin~100 fC
Qin~600 fC
points to note:charge injection edge also contributes here(~ 5 nsec => should deconvolve out)
actual disc. threshold value (~ 100 fC here)in our system will depend on: programmed Vth value programmed tript gain SiPM gain external gain ratio capacitors
=> many more careful and systematic measurements required here
this plot shows timewalkdependence on signal size
Mark Raymond - [email protected] - 16/11/05 9
summary
tript results with SiPM encouraging single p.e. spectra visible and charge splitting to get high/low gain channels works
linearity shows results consistent with previous chip measurements discontinuities occuring when discriminators fire need further study – try to reduce and/or understand how to manage in system
discriminator timing studies begun – more systematic study needed
our next priority investigate performance dependence on connection cable length between SiPM and tript look for degradation with cable length (noise, timing performance) – important to understand from detector design perspective (how far can front end boards be from SiPM’s) propose to try and do this with scintillator/wavelength shifting fibre -> SiPM system using cosmics and external scintillator trigger system to get reference timestamp to compare with SiPM/tript value
system currently under construction
Mark Raymond - [email protected] - 16/11/05 10
Photos
Trip-t (1st version)
charge injection splitbetween 2 adjacentchannels
2.5 V CMOScontrol lines
Mark Raymond - [email protected] - 16/11/05 11
Photos
Trip-t board
dECL -> 2.5 V CMOSlevel shift
digital pattern generatordECL outputs
ADC
