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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 5
STFC
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 7
STFC
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
STFC
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
STFC
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
STFC
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
STFC
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
STFC
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)
EE at SLHC CERN 15/04/08 R M Brown - RAL 14
STFC
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.