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 SiO 2 layer (Ionizing Dose)  (integrating measurement).

p-i-n

diodes Optically Stimulated Luminescence (OSL)

F.Ravotti

Bulk damage in high r (particle fluence)  Si-base (integrating measurement).

Charge buildup in sensitive material detrapped by IR stimulation (Ionizing Dose) 

(instantaneous measurement).

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 t ox F.Ravotti

Sub-linear Responses Build-up of charge in SiO 2  increase of the p-MOS Threshold Voltage  integrated Dose Measurement S threshold ~ 1 cGy; S decreasing over LHC Exp. RadMon Working Group 06/04/2004  .

3

RadFETs Details

1. MOS exposed in “zero bias” mode; (2-wires only readout, bigger dynamic range) 2. Long-distance readout of V th after I DS bias (seconds time-scale); 3. Operation at MTC: if T ~ constant, correction it is not needed; 4. Good reproducibility of the results  producer selection.

D

V

th

=



(particle type, energy, incidence angle, ..);

D

V

th

=



(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 mm 2 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  prompt time-scale (i.e. hours) , can induce big errors especially at LDR (> 20 % in a few hrs).

3. Interface states generation  delayed time-scale (i.e. years) , can strongly affect the devices long-time behaviour.

Devices have to be selected on the basis of their annealing F.Ravotti

behaviors 

Isochronal Annealing

LHC Exp. RadMon Working Group 06/04/2004 6

RadFETs Isochrones

Regular behaviours Data from CERN & CEM 2 - 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 SiO 2 .

F.Ravotti

Not suitable behaviours LHC Exp. RadMon Working Group 06/04/2004 7

OSLs General

(collaboration between CERN and CEM 2 – 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) F.Ravotti

Linear response (< 100 Gy) After L.Dusseau

Material used at CERN: SrS doped The readout completely reset the sensitive material !

S threshold = 100 m Gy; S dependent on readout electronics.

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 mm 2 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: 10 B(n, a ) 7 Li 

Thermal neutrons

1 H(n,p) 1 H 

Fast neutrons

OSL pure OSL+B OSL+PE 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

CERN-PS IRRAD2 Facility (FLUKA)

Neutron-Sensitive OSLs 2

89 % 1 % 99 % Thermal 11 % Fast Ljubljana Reactor - Activation measurements CERN OSL Ljubljana OSL F.Ravotti

3 % 87 % 97 % 13 % LHC Exp. RadMon Working Group 06/04/2004 11

3 cm x 1.5 cm

OSL on-line approaches

1. OSLs deposed on GaAsP photodiodes OSL+B

OSL

OSL pure Designed for Space Intl. Space Station, CUBESAT / PROBA2 (50 mGy – 100 Gy) OSL material + Radhard electronics = RADHARD INTEGRATED SENSOR F.Ravotti

Support for off-line readout OSL+Paraffin 2. Optical-Fiber system The sensor works in OSLs at the edge of a long HEP environment optical fiber  LED/PD not (CERN PS-IRRAD1) damaged by radiations.

LHC Exp. RadMon Working Group 06/04/2004 12

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), V F on-line readout over long-distances (2-wires); B. Sensitivity =  ( w ): w =1.2 mm  S ~ 1 mV / 10 8 cm -2 ; F range = 10 8 ÷ 10 12 cm -2 ( F eq ) w = 0.3 mm  S ~ 1.5 mV / 10 10 cm -2 ; F range = 10 12 ÷ 10 14 cm -2 ( F eq ) 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 ( F eq ): 1.0x10

12 ÷ 4.0x10

14 cm -2 - Sensitivity ( F eq ): 1.5 mV / 10 10 cm -2 (2) Strong T dependence: T c = -5 %·ºC -1 ; (3) Thermal annealing: < 10 % in the first 14 days.

F.Ravotti

(preliminary) Max D T 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 cm 2 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: • 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] Calibration campaign 2003 in the mixed g /n field of CERN-PS IRRAD2 facility Gafchromic  Sensitive Films • Formation of a stable dye polymer after irradiation; • Optical readout (color density); • Different sensitivities/ranges F.Ravotti

24 GeV/c protons (HD-810) 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

17 LHC Exp. RadMon Working Group 06/04/2004

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 CEM 2 - 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

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Neutrons Cross-sections

F.Ravotti

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Readout parameters

Active Dosimeter RadFETs (2003 sensor) PT100 Temp Probe External bias not needed electronics) BPW34F (w ~ 300 m m) not needed Pad structures not needed not needed DC

i

Readout Input = 10 DC

i

m A ÷ 160 m depending on MTC = 1 mA A 10-15 sec DC stimulation on LED with

i

= 50 mA Fast pulse (180 ms) with Forward

i

= 1 mA Leakage current at full depletion V = 100 V ?

Pre-irradiation output 1 V to 3 V depending on t ox noise ~ 200 with G out 0.5 V =10 ~ nA order m 0.1 V (0 ºC) V After irradiation output Reference Val.

~ 10 V (1.6 m m) ~ 4 V (0.25 m m) ~ 41 V (0.25 m m) 100 Gy 100k Gy ~ 2 V with G out =10 100 Gy ~ 50 V (linear operation) ~ mA order 4.x10

14 ( F eq ) cm -2 10 14 ÷ 10 15 cm -2 ( F eq ) # # F.Ravotti

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