Radiation Monitoring Technologies for the LHC Federico Ravotti (TS-LEA-CMS) Maurice Glaser (PH-TA1-SD) — Active Radiation Monitors RadFETs; OSLs; p-i-n diodes; — Passive Radiation Monitors.

Report
Radiation Monitoring
Technologies for the LHC
Federico Ravotti
(TS-LEA-CMS)
Maurice Glaser
(PH-TA1-SD)
— Active Radiation Monitors
RadFETs;
OSLs;
p-i-n diodes;
— Passive Radiation Monitors
Active Radiation Monitors
RadFETs
Build-up of charge in MOSFETs SiO2 layer
(Ionizing Dose)
 (integrating measurement).
Optically Stimulated
Luminescence (OSL)
p-i-n diodes
Bulk damage in high r Si-base
(particle fluence)
 (integrating measurement).
Charge buildup in sensitive material detrapped by IR
stimulation (Ionizing Dose)
 (instantaneous measurement).
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
2
RadFETs General
(1) e-/h+ pair generation;
(2) e-/h+ pair recombination;
(3) e- (~psec) / h+ (~sec) transport;
(4) hole trapping;
(5) Interface state delayed buildup.
g responses for
different tox
Build-up of charge in SiO2
Sub-linear
Responses
increase of the p-MOS Threshold Voltage
 integrated Dose Measurement
Sthreshold ~ 1 cGy;
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
S decreasing over .
3
RadFETs Details
1. MOS exposed in “zero bias” mode;
(2-wires only readout, bigger dynamic range)
2. Long-distance readout of Vth after IDS bias (seconds time-scale);
3. Operation at MTC: if T ~ constant, correction it is not needed;
4. Good reproducibility of the results  producer selection.
DVth=  (particle type, energy, incidence angle, ..);
DVth=  (packaging) in neutron field.
 Care has to be taken in the choice of the proper calibration &
packaging for a neutron/HEP enriched radiation environment!
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
4
RadFETs at CERN
g-ray calibrations (“zero bias” mode) from producers & measured at CERN
Bare die chips ~ 1-2 mm2 dimension !
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
5
RadFETs Instabilities
1. “Read-time” instability (“Drift-up”)  during readout, small error
(< 5 %) avoided by fixing the readout protocol.
2. Trapped charge annealing 
3. Interface states generation 
prompt time-scale (i.e. hours),
delayed time-scale (i.e. years),
can induce big errors especially
can strongly affect the devices
at LDR (> 20 % in a few hrs).
long-time behaviour.
Devices have to be selected on the basis of their annealing
behaviors  Isochronal Annealing
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
6
RadFETs Isochrones
Regular behaviours
Data from CERN & CEM2 - Montpellier
• Scaling annealing t  annealing T;
• Annealing periods at increasing T;
• Charge annealing is oxide
(i.e. manufacture) dependent;
• Simple and quick way to identify
not suitable behaviours;
• Informations about charge
spectrum in SiO2.
Not suitable behaviours
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
7
OSLs General
(collaboration between CERN and CEM2 – Montpellier University)
(1) e-/h+ pair generation and trapping;
(2) Infrared stimulation (800-1500 nm);
(3) Visible emission (500-700 nm)  Dose;
24 GeV/c protons (IRRAD1)
Material used at CERN: SrS doped
After L.Dusseau
The readout completely reset
Linear response
(< 100 Gy)
the sensitive material !
Sthreshold = 100 mGy;
S dependent on readout electronics.
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
8
OSLs Details
1. Radiation independent response (X, g, p, p, e, ..);
2. OSL materials characterized with off-line measurements (test bench);
3. Readout process takes 10-15 seconds;
4. Very low fading at room temperature (to be verified);
5. Pure OSL does not suffer radiation damage;
6. n-OSL tested for the first time: first
OSL Test bench
campaign with 5 mm2 samples
performed in 2 different neutron
environments.
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
9
Neutron-Sensitive OSLs 1
OSLs with enhanced neutron-sensitivity:
10B(n,a)7Li
 Thermal neutrons
1H(n,p)1H
 Fast neutrons
OSL pure
OSL+PE
OSL+B
OSL+PE+B
1. The pure OSL material is sensitive to the
Ionizing radiation only;
2. The n-OSLs show a 20-times increased
sensitivity.
3. Boron doping affects fading behaviour ?
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
10
Neutron-Sensitive OSLs 2
89 %
CERN-PS
IRRAD2
Facility
99 %
1%
(FLUKA)
11 %
Thermal
Fast
Ljubljana
Reactor
- Activation
measurements -
CERN OSL
3%
97 %
Ljubljana OSL
87 %
13 %
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
11
OSL on-line approaches
1. OSLs deposed on GaAsP photodiodes
OSL+B
OSL
OSL pure
Designed for Space
3 cm x 1.5 cm
Intl. Space Station,
CUBESAT / PROBA2
(50 mGy – 100 Gy)
OSL material + Radhard electronics
= RADHARD INTEGRATED SENSOR
The sensor works in
HEP environment
(CERN PS-IRRAD1)
F.Ravotti
Support for off-line readout
OSL+Paraffin
2. Optical-Fiber system
OSLs at the edge of a long
optical fiber  LED/PD not
damaged by radiations.
LHC Exp. RadMon Working Group 06/04/2004
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p-i-n diodes General
(1) Displacement damage in high r Si-base;
Macroscopic Effects:
(2) Resistivity increase  F (forward bias);
(3) Leakage current increase  F (reverse bias);
Forward bias operation:
A. Fast current pulse (~ms), VF on-line readout over long-distances (2-wires);
B. Sensitivity =  (w ):
w =1.2 mm  S ~ 1 mV / 108 cm-2 ; Frange = 108 ÷ 1012 cm-2 (Feq)
w = 0.3 mm  S ~ 1.5 mV / 1010 cm-2; Frange = 1012 ÷ 1014 cm-2 (Feq)
C. Commercial diodes BPW34F characterized in 2003.
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
13
BPW34F Osram diodes
(1) High-fluence measurements:
Response Curve
(CERN-PS IRRAD1 & IRRAD2 facilities)
- Linear behaviour (Feq):
1.0x1012 ÷ 4.0x1014 cm-2
- Sensitivity (Feq):
1.5 mV / 1010 cm-2
(2) Strong T dependence:
Tc = -5 %·ºC-1;
(3) Thermal annealing:
< 10 % in the first 14 days.
(preliminary)
F.Ravotti
Max DT over irradiations: ± 0.83 ºC
LHC Exp. RadMon Working Group 06/04/2004
14
“Pad” structures
Reverse bias operation:
(see next presentations)
Off-line measurements after
annealing (4 min 80 ºC)
1. ST, Italy “Pad structure” of 0.25
cm2 for bulk damage studies;
2. Off-line characterization;
3. Very wide fluence range;
4. Complex Annealing behaviour;
Possible “on-line” implementation
for high-sensitivity fluence
measurements
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
After M.Moll
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Passive Radiation Monitors
Polymer-Alanine (PAD) & Radio-Photo
Luminescent (RPL) Dosimeters:
Calibration campaign 2003 in the mixed
g/n field of CERN-PS IRRAD2 facility
• Formation of stable free radicals/color center
after irradiation;
• Readout by
CERN SC/RP (“TIS”);
• Well known dosimetry systems.
[NIM-B 83 (1993) pp. 181-188]
Gafchromic Sensitive Films
• Formation of a stable dye polymer after
irradiation;
• Optical readout (color density);
• Different sensitivities/ranges
24 GeV/c protons (HD-810)
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
16
Summary
RadFETs:
Responses in HEP/n environments fully characterized. Isochronal annealing studies
are ongoing with setup in Lab. 14-R-012.
OSLs:
Responses HEP fully characterized. Neutron-sensitive materials under development.
Annealing studies & test on new on-line configurations are planned.
BPW34F:
Particle responses fully characterized. More on Annealing & readout procedure.
Pad Structures:
Particle responses well known. Looking forward for an “on-line” readout.
Passive Monitors:
Daily used in the operation of the CERN-PS Irradiation Facilities.
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
17
and finally …
More on …
1. p-i-n diodes; RadFETs HEP/n responses, packaging dependence, annealing & instabilities:
CERN Technical Note EST/LEA/2003-03, July 2003
(EDMS No. 394670)
2. RadFETs fast-neutron response: Paper in preparation for NSS Rome, 2004
3. Special neutron-sensitive OSLs:
Paper submitted to RADECS Madrid, 2004 & CERN Preprints collection
4. Integration Issues:
CERN-PH-EP-2004-04, February 2004 (Presented at NSREC Atlanta, 2004)
5. Passive technologies, PS Irradiation facilities: http://www.cern.ch/irradiation
Acknowledgments …
- M. Moll, C. Joram, E. Tsesmelis from CERN;
- L. Dusseau, J R. Vaillé from CEM2 - Montpellier University;
- G. Sarrabayrouse (CNRS, France), A. Holmes-Siedle (REM, England) for their support in RadFETs studies;
- I. Mandic and M. Mikuz from the Josef Stefan Institute, Ljubljana, Slovenia.
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
18
Neutrons Cross-sections
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
19
Readout parameters
Active
Dosimeter
External bias
Readout Input
Pre-irradiation
output
After irradiation
output
Reference Val.
RadFETs
not needed
DC i = 10 mA ÷ 160 mA
depending on MTC
1 V to 3 V
depending on tox
~ 10 V (1.6 mm)
~ 4 V (0.25 mm)
100 Gy
~ 41 V (0.25 mm)
100k Gy
OSLs
(2003 sensor)
± 5V (on-board
electronics)
10-15 sec DC stimulation
on LED with i = 50 mA
noise ~ 200 mV
with Gout=10
~ 2 V with
Gout=10
100 Gy
BPW34F
(w ~ 300 mm)
not needed
Fast pulse (180 ms) with
Forward i = 1 mA
0.5 V
~ 50 V
(linear operation)
4.x1014 cm-2
(Feq)
Pad
structures
not needed
Leakage current at full
depletion V = 100 V ?
~ nA order
~ mA order
1014÷ 1015 cm-2
(Feq)
PT100 Temp
Probe
not needed
DC i = 1 mA
0.1 V (0 ºC)
#
#
F.Ravotti
LHC Exp. RadMon Working Group 06/04/2004
20

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