Radiation Sensor Characterization for the LHC Experiments Federico Ravotti, Maurice Glaser, Michael...

Radiation Sensor Characterization for the LHC Experiments

Federico Ravotti, Maurice Glaser, Michael Moll CERN PH/DT2 and TS/LEA

F.Ravotti 5th LHC Radiation Day 29-11-2005 2

Outline Sensor Catalogue;

Quality Assurance (QA) procedure for sensors;

RadFETs packaging;

Sensors readout board for LHC Experiments;

Sensors R&D: Readout procedure optimization for BPW34 p-i-n diodes;

New p-i-n diodes from Czech Republic (LBSD);

On-line dosimeter based on fibred OSL.

Conclusion.


(www.cern.ch/lhc-expt-radmon/)

Specifies sensors suitable for dosimetry in

the LHC experiments environment:

Mixed-LET radiation field;

~ 5 orders of magnitude in intensity.

Many devices tested but only a few

selected (e.g. only 2 out of 9 RadFETs)

Sensor Catalogue

2 x RadFETs (TID);

[REM, UK and LASS, France]

2 x p-i-n diodes (1-MeV eq);

[CMRP, AU and OSRAM BPW34]

1 x Silicon detectors (1-MeV eq).

[CERN RD-50 Mask]

Detailed discussion on the sensors

selection criteria see talk at

4th LHC Radiation Day!


Sensors QA ProcedureSuitable radiation response and intrinsic stability are not enough to

guarantee reliable measurements over a long time (e.g. 10 y. LHC).

Example of different radiation response

curves for Thin Oxide RadFETs from REM (see

Catalogue).

Compliance with electrical specifications to

keep working correctly under irradiation;

Homogeneous initial values to insure

reproducible measurements;

Sensors must be identified

one by one using their pre-

irradiation characteristics!

RadFET LAAS 1600 nmTmeas = 23.0 +/- 2.0 ºC , DTmax,step = 4.8 ºC

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

Temperature (ºC)

Una

nnea

led

Fra

ctio

n (%

)

Example of Annealing Behaviour at different doses for Thick Oxide RadFETs from LAAS

(see Catalogue).


Sensors QA ProcedureElectrical Tests on the

purchased sensor batches to

complies with specifications

Mounting bare-die sensors in a

proper packaging

Functional Verification Test

Delivery to the LHC Experiments

Integration in a specific PCB

circuit “sensor carrier”

Acceptance Tests

Functional Verification Test

Issue for TID Measurement(RadFETs Packaging)

For the

Experiments

with proper

readout boards

For the

Experiments

that need a

readout board


RadFETs:

• Ids – Vgs in linear and saturation regime;

• Ids – Vds in function of Vgs;

• Read-time stability of Vth;

p-i-n diodes:

• I-V in forward bias;

• Stability of VF (t);

Silicon Detectors:

• I-V & C-V in reverse bias;

• Stability of bulk IL (t).

Detector ST W339-N11

1.0E-10

1.0E-09

1.0E-08

1.0E-07

1.0E-06

0 5 10 15 20 25 30Reverse Bias (-V)

Cu

rre

nt (

-A)

6.0E-11

6.5E-11

7.0E-11

7.5E-11

8.0E-11

8.5E-11

9.0E-11

9.5E-11

1.0E-10

Ca

pa

cita

nce

(F

)Central Current

Capacitance

Electrical Tests

IV Forward bias at 20.5 ºC

0

0.1

0.2

0.3

0.4

0.5

0.6

0.00 0.50 1.00 1.50 2.00

Voltage (V)

Cur

rent

(A)

Example of I/V characteristics

of not-irradiated BPW34 diodes.

Example of I/V and C/V characteristi

cs of not-irradiated Detectors.


RadFETs Characteristics

REM Id vs. VgsVg =0 to -6V step 0.05V Vd= -100mV, -6V

1.E-141.E-131.E-121.E-111.E-101.E-091.E-081.E-071.E-061.E-051.E-041.E-03

0 1 2 3 4 5Vgs [V]

Ids

[A]

REM Id vs. VgsVg =0 to -6V step 0.05V Vd= -100mV, -6V

0.0E+00

2.0E-04

4.0E-04

6.0E-04

8.0E-04

0 2 4 6Vgs [V]

Ids

[A]

REM Id vs. Vds Vgs= -1, -2, -3, -4, Vd= 1 to -6V step 0.05V

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

0 1 2 3 4 5 6Vds [V]

Ids

[A]

Idss

VT

Sensors Acceptance/Rejection based on:

• Vth,0

• Idss

• Ids-Vds immune to kink effects

• Stability of Vth (t).

Tech. Spec. document existent


RadFETs Packaging

Commercial Packaging (i.e. TO-5, DIL) cannot satisfy all Experiment

Requirements(dimensions/materials)

Development / study

in-house at CERN

~10 mm2 36-pin Al2O3 carrier1.8 mm

• High Integration level:

up to 10 devices covering from mGy to kGy dose range;

• Customizable internal layout;

• Standard external connectivity; Calculated Radiation Transport

Characteristics (0.4 mm Al2O3):

X = 3-4 % X0;

e cut-off 550 KeV; p cut-off 10 MeV; photons transmission 20 KeV; n attenuation 2-3 %;

Full-Package Geometry designed

in GEANT4

Packaging under validation

(including lids effect) with

GEANT4 model in

collaboration with Genova

INFN (Riccardo Capra)


ATLAS ID(RMSB Hybrid)

DMILL structure

(nth damage)

PAD diode

BPW34 diodes

PT1000

[I. Mandic, JSI]

PCB with T control

4 x RADFETs

Rest of ATLAS

CMS (BCM 1)

[A. Macpherson, CERN]

p-i-n diode

Integration Issues

General-purpose plug-on I/O module for the monitoring and control of sub-

detector front-end equipment

ELMB (ADC) + DAQ


Sensors Readout Board PCB designed to host:

1 x RadFETs Packaging (5 channels)

5 x p-i-n sensors;

1 x Temperature sensor;

Fully customizable;

Small size (15 mm x 25 mm x 5 mm);

Signals available on a standard connector plug (12 pins) or

direct wire connection.

Board readable with commercial electronics:

Keithley Source-Meter 2400 and Agilent Switch

Matrix;

Price ~ 130 CHF/channel (if > 60 channels)

PCB can be used as passive dosimeter.


Outline Sensor Catalogue;

Quality Assurance (QA) procedure for sensors;

RadFETs packaging;

Sensors readout board for LHC Experiments;

Sensors R&D: Readout procedure optimization for BPW34 p-i-n diodes;

New p-i-n diodes from Czech Republic (LBSD);

On-line dosimeter based on fibred OSL.

Conclusion.


BPW34 Readout Optimization

1) Devices not manufactured to be dosimeters

(e.g. not sensitive to low );

2) Pre-irradiation helps to shift operation point

(see our last years talk);

To be studied in more detail:

A. Influence of readout parameters (current density and pulse

length) on diode’s response;

B. Long-term annealing of VF as function of IF and Temperature.

iF = 1 mA 200 ms

IV Forward bias after PROTON irradiation

0

0.1

0.2

0.3

0.4

0.5

0 10 20 30 40 50 60

Voltage (V)

Cur

rent

(A)

Current density:

eq > 21013 cm-2 “thyristor - like” behaviour;

Keep IF < 50 mA is a good precaution!

Tested readout currents 1 mA, 10 mA, 25 mA

eq

(1x1011 to 1x1015 cm-2)



0.1

1

10

100

1.00E+10 1.00E+11 1.00E+12 1.00E+13 1.00E+14 1.00E+15

Equivalent Fluence (cm-2)

Fo

rwa

rd V

olta

ge

(V

)

ProtonNeutron

0

12

3

4

56

7

89

10

1 10 100 1000 10000Time after current injection (ms)

Incr

ea

se o

f V

F (

mV

)

after ~ 11013 cm-2

IF = 1 mA; VF = 6.7 V

Current density

(radiation response at 25 mA vs. 1 mA):

eq < 21012 cm-2 negligible sensitivity increase;

eq > 21012 cm-2; S (25 mA) > 36 % S (1 mA);

Signs of heating effects eq ~ 11014 cm-2;

iF = 25 mA 100 ms

Pulse Length:

Keep the readout-time 200 ms is

advisable;

“optimized” pulse-length of 50 ms. Conclusion:

Current density and pulse length have to

be adopted to the user requirements

(fluence range, current density limitations

in electronics, etc….)


Annealing BPW after 1e14 cm-2 @ 80ºC

0

0.10.2

0.3

0.40.5

0.6

0.7

0.80.9

1

0 5000 10000 15000 20000Time (min)

VF/V

0

1 mA

10 mA

25 mA

Annealing of VF (IF):

Relative change of the voltage less significant at high injection levels!

(detailed study ongoing in the Temperature range 20 – 100 ºC)



Czech p-i-n diodes (LBSD)Long Base Silicon Diodes from CMI, Prague

Type “Si-1”:

• KERMA: 0.1-30 Gy (eq ~ 1.2x1012 cm-2)

• nF sensitivity: ~ 3 mV/109 cm-2

Type “Si-2”:

• KERMA: 0.01-5 Gy (eq ~ 2x1011 cm-2)

• nF sensitivity: ~ 3 mV/108 cm-2

1) Cheaper compared to the High Sensitivity diodes currently

presented in the Catalogue;

2) Two types are produced: one MORE SENSITIVE than the

currently used devices;

3) Recommended IF pulse for readout: 25 mA x 40 ms.

0

2

4

6

8

10

12

0.0E+00 2.0E+11 4.0E+11 6.0E+11 8.0E+11 1.0E+12

Dose (Gy)

DF

(V

) at

25

mA

x 4

0 m

s

Si-1 Broad n spectrum

Si-2 Broad n spectrum

Si-1 250 MeV p Low Flux

Si-2 250 MeV p Low Flux

Si-1 250 MeV p High Flux



Annealing studies ongoing to include

these products into Sensor Catalogue!


Fibred OSLs System

Laser System Driver

Oscilloscope

5 V/div1 M DC

50 ms/div

Tested at the TRIGA Reactor of the JSI, Ljubljana (Slovenia)

Quartz Radhard Fibers

Laser Light 60 mW

1 A/nW (@ OSL )

Visible light

~ 5 mgOSLCrystal


Fibred OSLs System

OSL Dose Vs Integration Time

0

1

2

3

4

5

6

7

8

0 5 10 15Time [s]

Dos

e [m

Gy] Vertical Scan of the irradiation tube

1

10

100

1000

10000

0 50 100 150

Position [cm]

Dos

e [m

Gy]

1) Preliminary Results (last week!!!) show the feasibility

of such a system in harsh and intense environment;

2) Test condition ~200 mGy/s with eq ~1.9x109 cm-2s-1

(values referred to 250 W reactor power at Z = 0).

Dose integrated in 6 sec time.

Sensitivity of the tested prototype ~ 0.1 mGy, but

minimal sensitivity probably higher; probe edge dimension < 1 mm2


Conclusion

Over 1200 sensors have been procured and ~ 1/3 have been tested

following the QA procedure here described. About 100 samples have been

delivered to LHC Experiments;

A dedicate packaging and a readout board for the sensors have been

produced;

R&D on sensors is carried out in parallel:

Improvement in the BPW34 readout protocol;

More sensitive p-i-n diodes are under studies added soon to the

Sensor Catalogue;

Very promising results obtained in OSL on-line dosimetry!

Radiation Sensor Characterization for the LHC Experiments Federico Ravotti, Maurice Glaser, Michael...

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