first results from silicon and diamond sensors k. afanasiev 1, i. emeliantchik 1, e. kouznetsova 2,...
TRANSCRIPT
First results from silicon and diamond sensors
K. Afanasiev1, I. Emeliantchik1, E. Kouznetsova2, W. Lohmann2, W. Lange2
1 NC PHEP, Minsk2 DESY Zeuthen
2
CVD diamond :
Radiation resistant ( up to 10 MGy) Fast (charge collection time ~ 10 ps) Low dielectric constant => Low capacitance
but Low signal : < ½ signal from silicon
Charge collection distance dc: cccc
vis QQL
dQ
3
Si - Diamond comparison
Silicon CVD-Diamond
Resistivity, ×cm 2.3×105 1013-1016
Carrier density, cm-3 15×1010 <103
Dielectric constant 11.9 5.7
Capacitance (1 cm2, 500 m), pF 35 17
Breakdown field, V/cm 3×105 107
Energy/(e--h pair), eV 3.6 13
Mobility, cm2/(V×s)e- 1350 1800 - 2200
h 480 1200 - 1600
Average e--h number per 100 m (for MIP) 9200 3600
Energy deposition per 100 m (for MIP), keV 40 50
Charge collection distance dc, m 60 - 250; dc = f(l)
4
Test Set Up
5 mm SC. 2
SC. 1
Si/diamond
lead (for cosmics only)
Sr/cosmics
&
Gate
PA
discr
discr
delay
ADC
5
Test Set Up
6
PA+ADC calibration
y = 336.52x + 104.30
500
1000
1500
2000
2500
3000
0 2 4 6 8 10Q, fC
AD
C c
hann
elElectronics calibration PA : VV 50-3
(charge sensitive)
ADC : CAEN V265 12 bit
ENC = 700 e
(diamond sensorconnected )
gen
50
1 pF
Cw Cv = g·Cf
Cf
7
Sr source + triggering system
Sr
Y
E, MeV
Sr
Y
5 mm
90Sr
SC. 2
SC. 1
Si/diamond(300 m)
&
8
Sr source + triggering system
Emip = 1.25 MeVdE/dx = 3.56 MeV/cmR = 0.3 cm Emip = 1.5 MeV
dE/dx = 5.57 MeV/cm R = 0.2 cm
=> ~mip - signal
9
Signals from 90Sr – silicon :
Si(mip)
10
Signals from 90Sr – diamond : Selftriggering:
discr
delay
in
gate
ADC
PAdiamond
Sr
Diamond(noise)
Diamond(whole -spectra)
11
Noise level is not optimal for signal/noise separation Possible solutions :
Noise optimization of the existing preamplifieror
Switch to Amptek A250:
New trigger scintillator matching the size of the sensor
Problems and further steps :
Expected noise
≤ 350 e
12
Fraunhofer Institute (Freiburg) : (12 x 12 mm) 300 and 200 m Different surface treatments
Prokhorov Institute (Moscow)
(Dubna group)
Further steps :
New diamond samples :