EE at SLHC CERN 15/04/08 R M Brown - RAL 1

STFC

RAL EE at SLHC

• What do we expect at SLHC?

• EE Layout

• VPT vulnerability to radiation- Faceplate darkening

- Photocathode ageing

• HV Filter card

• Active electronics

• Other EE components

• Induced activity

• Summary

EE at SLHC CERN 15/04/08 R M Brown - RAL 2

STFC

RAL What do we expect at SLHC?

KoutchoukIoP Liverpool

Jun 2007

Inst

anta

neou

s lu

min

osity

(cm

-2s-1

)

Year

SLHCLHC∫L ~ 440 fb-1 ∫L ~ 3040 fb-1

Total ∫ L ~ 3500 fb-1

(107 s/year, 50% efficiency)(cf ECAL TDR: ∫L ~ 500 fb-1)

~ x7

EE at SLHC CERN 15/04/08 R M Brown - RAL 3

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RAL Dose versus in EE (LHC)

EE at SLHC CERN 15/04/08 R M Brown - RAL 4

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RAL Neutron fluence (>100keV) in EE

EE at SLHC CERN 15/04/08 R M Brown - RAL 5

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RAL Fluence and Dose for 500 fb-1

Neutron + charged hadron fluence (cm-2) for E>100 keV

500 fb-1

500 fb-1

Absorbed dose (Gy)

Immediately behind crystals

500 fb-1

500 fb-1

EE at SLHC CERN 15/04/08 R M Brown - RAL 6

STFC

RAL Layout of EE elements

EE at SLHC CERN 15/04/08 R M Brown - RAL 7

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RAL Faceplate exposures to n and

300 350 400 450 500 550 600 650 700 750

0,0

0,2

0,4

0,6

0,8

1,0

C-96 before irradiation C-96 after irradiation US-49C before irradiation US-49C after irradiation

Lig

ht t

rans

mitt

an

ce (

a.u

.)

Wavelength (nm)

Neutron fluence is 7x1014 n/cm2 (Reactor)

Accompanying -dose ~100 kGyRelative loss at 425 nm = 25%

For comparison, expected exposures at LHC (500 pb-1) at = 3 are:7x1014 n/cm2 and 50 kGy

-0.02

0

0.02

0.04

0.06

0.08

0.1

250 350 450 550 650 750

(nm)

Induce

d

abso

rpti

on

Induced absorption vs wavelength for 1mm thick sample of US-49C exposed to 20kGy (60Co)( = 2.6 at LHC)

Light loss (PWO) ~ 9%

EE at SLHC CERN 15/04/08 R M Brown - RAL 8

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RAL Extrapolation to SLHC exposures

0 5 10 15 20 25 30 35 40 45 500,7

0,8

0,9

1,0

T/T

0 (a

.u.)

Irradiation dose (kGy)

● US-49A

■ US-49CX VPT anode response

Transmission loss for PWO light under 60Co irradiation

A faceplate of US-49A glass has been irradiated up to 1250 kGy

- The damage tends to saturate and the ratio:

(T/T0)450 (350 kGy) 1.7 x (T/T0)450 (50 kGy)

For US-49C: loss of PWO light < 20% for 350 kGy ( = 3.0 at SLHC)

A US-49A faceplate was exposed to 1016 n/cm2 with an accompanying dose of 1600 250 kGy

Unfolding the neutron damage using extrapolated 60Co data (and ignoring s from induced activity in the glass):

T/T0 (neutron) < 15% for < 3.0 at SLHC

( T/T0 (neutron) < 30% for US-49C at SLHC????)

EE at SLHC CERN 15/04/08 R M Brown - RAL 9

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RAL Photocathode lifetime

VPT Photocurrent (nA)

2.9 8.0

2.5 2.5

2.0 0.6

1.6 0.1

Photocathode current for L =1034 cm-2s-1 0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25 30 35

Time [ Days]

Me

an

[%

of

firs

t re

ad

ing

]

0

4

8

12

16

20

DC

Ga

in

RIE #72 @ B = 0 Tesla, HT = 800/600 V

RIE #72 @ B = 0 Tesla, DC Gain

IK(0) = 200 nA

0

20

40

60

80

100

0 2 4 6 8 10 12

Time[days]

Me

an

[% o

f fi

rst

rea

din

g]

RIE #50, B = 1.8 T, DC LED @ 200 nA

RIE #50, B = 0 T, DC LED @ 200 nA

IK(0) = 200 nA30 days at IK(0) = 200 nA

~ 650 fb-1 at = 2.9

~ 2000 fb-1 at = 2.5

EE at SLHC CERN 15/04/08 R M Brown - RAL 10

STFC

RAL HV Filter Card components ()

Component Value

Capacitor 1 nF

Capacitor 470 pF

Resistor 22 M

Resistor 10 M

Resistor 10 M

Resistor 10 M

0.0

0.4

0.8

1.2

1.6

101 103 105 107

Cap

acita

nce

(pF

)Frequency (Hz)

0.0

0.4

0.8

1.2

1.6

101 103 105 107

Cap

acita

nce

(pF

)

Frequency (Hz)

Before irradiation After 135 kGy

HV Filter card components irradiated to

135 kGy (60Co) (~ SLHC at = 2.6)

- Small change in capacitor values (slight improvement in leakage current)

- Negligible change in resistor values

EE at SLHC CERN 15/04/08 R M Brown - RAL 11

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RAL HV Filter Card components (n)

HV Filter card components irradiated to 1015 n/cm2 (spallation spectrum at ISIS)

( > 3.0 at LHC, ~ 2.0 at SLHC )(While biased at 1 kV)(Components similar but not identical to final selection)

- Small change in capacitor values (slight improvement in leakage current)- Negligible change in resistor values- No breakdown up to 2 kV

Resistors

Capacitors

EE at SLHC CERN 15/04/08 R M Brown - RAL 12

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RAL Active electronicsMGPA tested to 50 kGy (~1/3 worst SLHC)(10 keV X-rays at ~10 kGy/h)

3% reduction in gain (pulse shape unchanged)

APV25 exposed to 2x1014 /cm2 (300/MeV/c) 15% reduction in gain

Optical link components (Tracker version) tested to 1.5 MGy (60Co) and ~5x1015 n/cm2 (18 MeV)(~10x SLHC for EE)

– loss in fibres small – TX (LLD ASIC + laser diodes) OK – Optical cables OK – Optical connectors appear OK – QR codes OK – PCB and connector embrittlementn – Lasers die at 2-3 1015 n/cm2

Barrel Trigger Tower irradiated with p (63 MeV)to 1.5x1013 p/cm2 (20 kGy at 1.7 Gy/s)(Dose ~worst LHC, Hadron fluence ~1/3 worst LHC)Tower still working at end of exposure

Will LV Regulators survive 5x1014 n/cm2 ?

100

200

300

400

kGy

Inner limit of active electronics

3.0 2.6 2.0 1.6Absorbed dose

for 3500 fb-1

200 600 1000 1400Radial distance from beam (mm)

5.0

4.0

3.0

2.0

1.0 Hadron fluence at ADCs z = 3520 mm

Active electronics behind polyethylene moderator

1015/cm2

Neutron fluence for 3500 fb-1

EE at SLHC CERN 15/04/08 R M Brown - RAL 13

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RAL Radiation tests of other components

2 2.6 320-50 100 200 300 350 400 500

DC 3145 VPT-xtal glue

HT cable, 2KV, LO-GE No461RG 179PE signal cable (not final choice)

Thermal compoundCarbon fibre alveolar composite strength tests to 5 MGy!

Eta (SLHC equivalent) Dose (kGy)

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RAL EE Activation

0 100 200 300 400z(cm)

0

100

150

50

r(cm)

Estimated dose rate in Sv/h after 60 d at L = 5x1033cm-2s-1 and 1 d cooling. (CMS closed)

After 4 months cooiling the dose rates are ~2.5x lower

150

54

24

Occupational dose limits:- 1 mSv/wk- 15 mSv/yr

Assume induced activity levels at SLHC ~10xLHC

Time to Annual limit at = 3 is ~10 h

LHC (ECAL TDR)

EE at SLHC CERN 15/04/08 R M Brown - RAL 15

STFC

RAL Summary

Passive components: – including HV filter card – OK

Active electronics:- Optical links - OK

- MGPA gain -15% at = 2.6?- Trigger towers not tested to full EE fluence at LHC!!

VPTs:- Faceplate darkening -30%- Photocathode ageing -40%

Combined loss 60%?Crystals:

- Ask Francesca!

EE at SLHC CERN 15/04/08 R M Brown - RAL 16

STFC

RAL Endcap upgrade for SLHC?

At VPTs:

Dose(=2.2)/Dose(=3.0) ~1/10 (neutron fluence ~1/3)~25% (18/71) Supercrystals are at

>2.2

Replace for SLHC?Unfortunately, complete rows of supercrystals must be dismounted to replace inner units – remote handling!

VPTs with Ce-glass windows – very rad-hard

But photocathode ageing depends on integrated charge - NB LYSO has a high light yield and would accelerate this effect.