Transcript ppt

EE at SLHC
STFC
RAL
• 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
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What do we expect at SLHC?
∫L ~ 440 fb-1
LHC
SLHC
∫L ~ 3040 fb-1
Total ∫ L ~ 3500 fb-1
(107 s/year, 50% efficiency)
(cf ECAL TDR: ∫L ~ 500 fb-1)
Instantaneous luminosity (cm-2s-1)
 ~ x7
Koutchouk
IoP Liverpool
Jun 2007
Year
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Dose versus  in EE (LHC)
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Neutron fluence (>100keV) in EE
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Fluence and Dose for 500 fb
-1
500 fb-1
500 fb-1
Neutron + charged hadron fluence (cm-2) for E>100 keV
Immediately
behind crystals
500 fb-1
500 fb-1

Absorbed dose (Gy)
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Layout of EE elements
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Faceplate exposures to n and g
1,0
Neutron fluence is 7x1014 n/cm2 (Reactor)
Accompanying g-dose ~100 kGy
Relative loss at 425 nm = 25%
0,8
0,6
C-96 before irradiation
C-96 after irradiation
US-49C before irradiation
US-49C after irradiation
0,4
0,2
For comparison, expected exposures at
LHC (500 pb-1) at  = 3 are:
7x1014 n/cm2 and 50 kGy
0,0
300
350
400
450
500
550
600
650
700 750
Wavelength (nm)
Induced absorption
0.1
Induced absorption
Light transmittance (a.u.)
RAL
Induced absorption vs wavelength
for 1mm
thick
sample of US-49C
Glass
30743a
exposed to 20kGy g (60Co)
( = 2.6 at LHC)
0.08
Light loss (PWO) ~ 9%
0.06
0.04
0.02
0
250
350
450
550
-0.02
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Wavelength (nm)
650
750
l (nm)
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Extrapolation to SLHC exposures
Transmission loss for PWO
light under 60Co irradiation
T/T0 (a.u.)
1,0
- The damage tends to saturate and the ratio:
(DT/T0)450 (350 kGy)  1.7 x (DT/T0)450 (50 kGy)
0,9
● US-49A
■ US-49C
0,8
A faceplate of US-49A glass has been irradiated up to
1250 kGy
 For US-49C: loss of PWO light < 20% for 350 kGy
( = 3.0 at SLHC)
X VPT anode response
0,7
0
5
10
15
20
25
30
35
40
45
50
Irradiation dose (kGy)
A US-49A faceplate was exposed to 1016 n/cm2 with an
accompanying g dose of 1600  250 kGy
Unfolding the neutron damage using extrapolated 60Co
data (and ignoring gs from induced activity in the glass):
 DT/T0 (neutron) < 15% for  < 3.0 at SLHC
( DT/T0 (neutron) < 30% for US-49C at SLHC????)
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Photocathode lifetime
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2.9
8.0
2.5
2.5
2.0
0.6
1.6
0.1
Photocathode current for L =10
34
20
IK(0) = 200 nA
90
Mean [% of first reading]

100
VPT Photocurrent
(nA)
80
16
70
60
12
50
40
8
RIE #72 @ B = 0 Tesla, HT = 800/600 V
30
RIE #72 @ B = 0 Tesla, DC Gain
20
-2 -1
cm s
DC Gain
STFC
4
10
0
0
0
5
10
15
20
25
30
35
Time [ Days]
100
IK(0) = 200 nA
Mean[% of first reading]
30 days at IK(0) = 200 nA
 ~ 650 fb-1 at  = 2.9
 ~ 2000 fb-1 at  = 2.5
80
60
40
RIE #50, B = 1.8 T, DC LED @ 200 nA
RIE #50, B = 0 T, DC LED @ 200 nA
20
0
0
2
4
6
8
10
12
Time[days]
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HV Filter Card components (g)
1.6
Capacitance (pF)
Capacitance (pF)
1.6
1.2
0.8
Before irradiation
0.4
0.0
101
1.2
0.8
After 135 kGy
0.4
0.0
103
105
Frequency (Hz)
107
101
103
107
Frequency (Hz)
Component
Value
Capacitor
1 nF
Capacitor
470 pF
Resistor
22 MW
Resistor
10 MW
- Small change in capacitor values
(slight improvement in leakage current)
Resistor
10 MW
- Negligible change in resistor values
Resistor
10 MW
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HV Filter card components irradiated to
135 kGy (60Co) (~ SLHC at  = 2.6)
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HV Filter Card components (n)
Resistors
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
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Capacitors
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Active electronics
400
MGPA tested to 50 kGy (~1/3 worst SLHC)
kGy
(10 keV X-rays at ~10 kGy/h)
 3% reduction in gain (pulse shape unchanged) 300
APV25 exposed to 2x1014 p/cm2 (300/MeV/c)
 15% reduction in gain
200
Optical link components (Tracker version) tested
to 1.5 MGy (60Co) and ~5x1015 n/cm2 (18 MeV)
100
(~10x SLHC for EE)
 g – loss in fibres small
– TX (LLD ASIC + laser diodes) OK
– Optical cables OK
5.0
– Optical connectors appear OK
15
10 /cm2
– QR codes OK
4.0
– PCB and connector embrittlement
 n – Lasers die at 2-3 1015 n/cm2
3.0
Barrel Trigger Tower irradiated with p (63 MeV)
to 1.5x1013 p/cm2 (20 kGy at 1.7 Gy/s)
2.0
(Dose ~worst LHC, Hadron fluence ~1/3 worst
LHC)
1.0
Tower still working at end of exposure
Will LV Regulators survive 5x1014 n/cm2 ?
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 3.0
2.6
2.0
1.6
Absorbed dose
for 3500 fb-1
Inner limit of
active electronics
Neutron fluence
for 3500 fb-1
Active electronics behind
polyethylene moderator
Hadron fluence at ADCs
z = 3520 mm
200
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1000
1400
Radial distance from beam (mm)
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Radiation tests of other components
Eta (SLHC equivalent)
2
Dose (kGy) 20-50 100
DC 3145 VPT-xtal glue
2.6
200
3
300 350 400
500
HT cable, 2KV, LO-GE No461
RG 179PE signal cable (not final choice)
Thermal compound
Carbon fibre alveolar composite strength tests
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 to 5 MGy!
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EE Activation
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LHC (ECAL TDR)
150
24
r(cm)
100
54
Estimated dose rate in mSv/h after
60 d at L = 5x1033cm-2s-1 and 1 d
cooling. (CMS closed)
50
150
After 4 months cooiling the dose
rates are ~2.5x lower
0
0
100
200
300
z(cm)
400
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
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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!
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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.

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