Vittorio Palmieri
Cryogenic Operation of
Si Detectors: the
Lazarus Effect
Vittorio Palmieri
Laboratorium fuer Hochenergiephysik, Universitaet Bern,
Sidlerstrasse 5, 3012 Bern, Switzerland
on behalf of the
CERN-RD39 Collaboration
http://www.cern.ch/RD39
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Vittorio Palmieri
Outline
• Properties of Si at cryogenic
temperatures
• CCE of heavily irradiated Si
detectors at cryogenic
temperatures:
• 1014 n/cm2
• 1015 n/cm2
• Neutralization of induced
defects: the Lazarus effect
• Low cost “ohmic” devices
• Segmented devices: irradiated
DELPHI module (5 1014 n/cm2)
• Low mass cooling
• Conclusions
• Future trends
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Vittorio Palmieri
Properties of Silicon at
Cryogenic
Temperatures
C. Canali et al., Phys. Rev. B 12 (1975) 2265
G. Ottaviani et al, Phys. Rev. B 12 (1975) 3318
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Vittorio Palmieri
Radiation Hardness of
Silicon at 300 K
E. Borchi et al., Nucl. Phys. B (Proc. Suppl.) 61B (1998) 481
The ROSE Collaboration (RD48) Status Report, CERN/LHCC 97-39 1997
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Vittorio Palmieri
1.2 1014 n/cm2
Irradiated Si Detectors
Operated at 4.2 K, 77 K
and 195 K
• Irradiated at room temperature
at TAPIRO, ENEA Italy
• Stored at room temperature and
bonded, therefore fully reverse
annealed (RA)
• Material and process:
– Al/n+/n/p+/Al
1.8 kW-cm
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Vittorio Palmieri
I-V Characteristic
1.2 1014 n/cm2 RA
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Vittorio Palmieri
M.I.P.s Signal Charge
and Timing
77 K
50 V
C. Da Via’ et al., Proc. of the International Conference on GaAs, Nucl. Instr. and Meth. in Phys. Res. A (1998) in press
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Vittorio Palmieri
Charge Collection
Efficiency
1.2 1014 n/cm2 RA
C. Da Via’ et al., Proc. of the International Conference on GaAs, Nucl. Instr. and Meth. in Phys. Res. A (1998) in press
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Vittorio Palmieri
2.2 1015 n/cm2
Irradiated Si Detectors
Operated at 4.2 K, 77 K
and 195 K
• Irradiated at room temperature
at TRIGA, JSI Slovenia
• Stored at room temperature and
bonded therefore fully reverse
annealed (RA)
• Different materials and
processes:
– Al/n+/n/p+/Al 1.8 kW-cm O2
– Al/n+/n/p+/Al 2.7 kW-cm
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Vittorio Palmieri
I-V Characteristic
2.2 1015 n/cm2 RA
300K I-V
300K I-V
0.E+00
-12
-10
-8
-6
-4
-2
1.E-05
0
-5.E-05
1.E-05
-1.E-04
Current (A)
-2.E-04
-3.E-04
Current (A)
8.E-06
-2.E-04
6.E-06
4.E-06
-3.E-04
2.E-06
-4.E-04
0.E+00
-4.E-04
0
0.2
Voltage (V)
0.4
0.6
0.8
1
Voltage (V)
77K I-V
1.E-08
8.E-09
6.E-09
Current (A)
4.E-09
2.E-09
-100
-80
-60
-40
0.E+00
-20 -2.E-09 0
20
40
60
80
100
-4.E-09
-6.E-09
-8.E-09
-1.E-08
Voltage (V)
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Vittorio Palmieri
M.I.P.s Signal Charge
and Timing
77 K
250 V
V.G. Palmieri et al., Nucl. Instr. and Meth. in Phys. Res. A 413 (1998) 475
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Vittorio Palmieri
Charge Collection
Efficiency
2.2 1015 n/cm2 RA
V.G. Palmieri et al., Nucl. Instr. and Meth. in Phys. Res. A 413 (1998) 475
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Vittorio Palmieri
The Lazarus Effect
St. John at al., The Bible, New Testament, ~100
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Vittorio Palmieri
Radiation Induced
Defects in Silicon
Ec
Ef
Ev
Electron Traps (Vacancies Related)
V6
CICS(B)
VO
CICS(A)
V2(=/-)+Vn
V2(-/0)+Vn
very shallow
Ec - 0.11eV
Ec - 0.17eV
Ec- 0.17eV
Ec-0.22eV
Ec-0.40eV
Holes Traps (Interstitial Related)
0.38/cm
0.63
CI
Ev+0.28eV
0.38
CI O I
EV+0.36eV
0.96
0.96 (Disappears after annealing)
1.5 (disappears after annealing)
1.2 (depends on [Cs] and[OI])
The ROSE Collaboration (RD48) Status Report, CERN/LHCC 98-39 1998
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Vittorio Palmieri
The Lazarus Effect
T = 300 K
e
conduction band
electron trapping
electron de-trapping
hole trapping
h
hole de-trapping
valence band
T = 77 K
e
conduction band
e
trap filled
trap filled
h
valence band
h
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Vittorio Palmieri
The CERN RD39
Collaboration
CERN/LHCC 98-27
DRDC P53 Add. 1
August 12, 1998
ADDENDUM TO PROPOSAL DRDC P53
RD39 Collaboration:
Kurt Borer, Stefan Janos, Vittorio Palmieri  and Klaus Pretzl,
LHEP, University of Bern;
Zheng Li,
Brookhaven National Laboratory, USA;
Eric Heijne, Carlos Lourenço, Tapio Niinikoski *, Iztok Ropotar and Peter Sonderegger,
CERN, Geneva, Switzerland;
Emilio Borchi, Mara Bruzzi and Silvia Pirollo,
INFN and University of Florence, Italy;
Sylvie Chapuy and Zlatko Dimcovski,
University of Geneva, Department of Radiology, Switzerland;
William Bell and Kenway Smith,
Glasgow University, U.K.;
Peter Berglund, Jaakko Koivuniemi and Martti Valtonen,
Helsinki University of Technology, Espoo, Finland;
Oleg Mukhanov,
HYPRES Inc., N.Y., USA;
Wim de Boer, Eugene Grigoriev and Stephan Heising,
IEKP, Karlsruhe University, Germany;
Luca Casagrande,
LIP, University of Lisbon, Portugal;
Vladimir Cindro, Marko Mikuz and Marko Zavrtanik,
Jozef Stefan Institute and Dept. of Physics, University of Ljubljana, Slovenia;
Cinzia Da Viá, Igor Konorov and Stephan Paul,
Technical University, Munich, Germany;
Salvatore Buontempo, Nicola D'Ambrosio, Valeria Granata, Sergio Pagano and Gennaro
Ruggiero,
INFN and University of Naples, Italy;
Susumu Takada,
Saitama University, Japan;
Antonio Esposito,
ETL, Tsukuba, Japan;
Jorma Salmi, Heikki Seppä and Ilpo Suni,
VTT, Espoo, Finland.

co-spokesperson
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Vittorio Palmieri
Temperature
Dependence
10^15 RA 250 V "reverse"
25%
CCE
20%
15%
10%
5%
0%
75
95
115
135
155
175
Temperature (K)
10^15 NRA 250 V "reverse"
30%
25%
CCE
20%
15%
10%
5%
0%
75
100
125
150
175
200
225
Temperature (K)
Gennaro Ruggiero
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Vittorio Palmieri
Voltage Dependence
10^15 RA 77 K
70%
60%
50%
CCE
40%
30%
20%
10%
-250
-150
0%
-50
50
150
250
150
250
Bias Voltage (V)
10^15 NRA 77 K
80%
70%
60%
CCE
50%
40%
30%
20%
10%
-250
-150
0%
-50
50
Bias Voltage (V)
Gennaro Ruggiero
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Vittorio Palmieri
1.0 1015 n/cm2
Irradiated Si “Ohmic
Device”
• Irradiated at room temperature
at TRIGA, JSI Slovenia
• Stored at room temperature and
bonded (4min @ 80C = 2weeks
at 300C) therefore fully RA
• Material and process:
– Al/n+/n/n+/Al
5 kW-cm
After irradiation
Before irradiation
+
+
+
+
-
+
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Vittorio Palmieri
I-V Characteristic
300K I-V
300K I-V
8.E-05
0.E+00
-12
-10
-8
-6
-4
-2
0
7.E-05
-1.E-05
6.E-05
Current (A)
Current (A)
-2.E-05
-3.E-05
5.E-05
4.E-05
3.E-05
-4.E-05
2.E-05
-5.E-05
1.E-05
0.E+00
-6.E-05
0
2
4
Voltage (V)
6
8
10
12
Voltage (V)
77K I-V
1.E-07
8.E-08
6.E-08
Current (A)
4.E-08
2.E-08
0.E+00
-100
-80
-60
-40
-20
-2.E-08
0
20
40
60
80
100
-4.E-08
-6.E-08
-8.E-08
-1.E-07
Voltage (V)
1.0 1015 n/cm2 RA
Gennaro Ruggiero
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Vittorio Palmieri
M.I.P.s Signal Charge
and Timing
77 K
250 V
Gennaro Ruggiero
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Vittorio Palmieri
Charge Collection
Efficiency
77 K
80%
70%
60%
CCE
50%
40%
30%
20%
10%
-250
-150
0%
-50
50
150
250
Bias Voltage (V)
1.0 1015 n/cm2 RA
Gennaro Ruggiero
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Vittorio Palmieri
Liquid Nitrogen
Cooling
• Non-flammable
• Non-toxic
• Easy to handle
• High cooling power
• Environmentally friendly
• Available everywhere
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Vittorio Palmieri
RD39/COMPASS
August Test Beam
RD39 cryostat
COMPASS m-strips
telescope
muon-beam
DELPHI strips
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Vittorio Palmieri
DELPHI Module
hybrid
mx6
n-side
p-side
mx6
p-side
n-side
Detectors: Hamamatzu
320 mm
5.75 x 3.2 cm2
3-6 Kohm cm
p-side 640 strips
strip pitch 25 mm
r-o pitch 50 mm
n-side 640 strips (p-stops)
strip pitch 42 mm
r-o pitch 42 mm
V. Chabaud et al., CERN-PPE/95-86, 1995
Electronics:10 x MX6
128 input channels
CMOS technology
2.5 MHz speed
1.5 ms peaking time
s/n degrades by 8.5%
for every 100Gy of
noise
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Vittorio Palmieri
Irradiated (Dead)
Detector
Laser Scan
5 1014 p/cm2 NRA
Peter Chochula and Paula Collins
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Vittorio Palmieri
Operation in the Cold
77K
hybrid
mx6
mx6
hybrid
mx6
mx6
n-side
Det 1
p-side non-irr
n-side
p-side
p-side
Det 2
n-side 5 1014p/cm2
beam
Temperature (K)
2nd module on !
T hybrid D1
T hybrid D2
T bath
Time (s)
William Hamish Bell and Luca Casagrande
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Vittorio Palmieri
Back from the Dead
Luca Casagrande and Paula Collins
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Vittorio Palmieri
Temperature and
Voltage Dependence
30V 110K
T
90V
110K
V
90V 125K
Luca Casagrande and Paula Collins
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Vittorio Palmieri
Liquid Nitrogen Low
Mass Cooling
• Cooling must be taken as an
integral part of engineering (not
an add-on)
• Power must be absorbed where
it is produced
– detector: < 1 µW/cm2
– read-out: ~ 3 mW/strip
• Support structures: conduction
is negligible if cooling is
integrated
• Vacuum isolation is needed for a
reliable low-mass system
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Vittorio Palmieri
RD39 Module
Tapio Niinikoski
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Vittorio Palmieri
Conclusions
• Cryogenic cooling dramatically improves
radiation hardness of silicon detectors
•After 1014 n/cm2 irradiation 100% CCE
is achieved with only 50 V detector bias
•After 1015 n/cm2 irradiation a m.i.p.,
most probable signal of 13000 e, is
measured at 200 V detector bias. This
corresponds to 50% CCE
•No difference is found between room
temperature and 195 K operation
•Detectors storage at room temperature
slightly affect the results (many months)
•Cooling needed only during operation
•Similar results apply to segmented devices
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Vittorio Palmieri
Future Trends
•Low mass cooling system for a full tracker
(2 geometry) under construction
•Ohmic detectors could result in a much
cheaper and more reliable solution
•Need for evaluation of performances of
irradiated and non-irradiated FET electronics
at cryogenic temperatures
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