Consequences of upgrade for Calorimeters
Answers to the following questions:
1)
What is needed to be able to sustain a 2x1033 luminosity (concerning both
electronics and mechanics (rates, occupancies, radiation damage))?
2)
What if the readout is performed at:
a) 40 MHz
b) 1 MHz with a factor 40 more front-end storage
3)
Which groups are interested in an upgrade, with which manpower (and
related money)?
upgrade workshop Jan 07
1
Andreas Schopper
What is needed to be able to sustain a 2*10**33 luminosity?
Effect on present electronics and on present detector modules!
Occupancy:
9 ECAL/HCAL
¾ The fast pedestal subtraction in ECAL/HCAL assumes there is no energy in the cell in
at least one of the two preceding beam crossing
¾ If beam crossings are every 50 ns this is automatically fulfilled, otherwise MC is needed
to evaluate the effect at 2x1033
9 PS/SPD:
¾ With PS/SPD no dynamic pedestal subtraction is done, so this should be safe
Radiation damage:
9 Electronics
¾ On electronics platform one expects 10 krad/year at 2x1033
¾ 50 krad in 5 years for new FE board components seems just OK even with present day
components
9 Detectors
¾ For ECAL a replacement of modules after a 2 Mrad dose is foreseen in TDR
¾ Possibility of replacement of 48 modules in most inner ECAL region has been foreseen
¾ HCAL modules cannot be replaced without dismantling detector
¾ PS and SPD scintillators are replaceable
upgrade workshop Jan 07
2
Andreas Schopper
Exchangeable ECAL modules in central part
48 out of 176 inner
modules could be
replaced
upgrade workshop Jan 07
3
Andreas Schopper
Electromagnetic Calorimeter
(CALO TDR)
Expected radiation dose at L=2x1032
1
10
10
10
10
-1
Inner Module: 250 krad/y (MC)
a)
-2
-3
10
10
10
inner module:
0.25 Mrad/y
at shower max
(MC)
e.m.
-4
2
0.15
X axis (cm)
1
10
0.25
0.2
10
Mrad/year
Longitudinal dose in the LHCb ECAL
Mrad/year
Mrad/year
Radiation dose in the LHCb ECAL
0.1
(MC) b)
-1
FE card: 1 krad/y
-2
hadronic
0.05
-3
-4
10
0
2
10
20
30
40
60
70
Plastic plate
Y axis (cm)
Î At 2x1033 : FE card 10 krad/y ; inner module 2.5 Mrad/year
upgrade workshop Jan 07
50
4
Andreas Schopper
Energy resolution of series modules measured in testbeam
¾ For a given cell size and sampling fraction the constant term in energy
resolution of an ECAL module is determined by the uniformity in response!
¾ The transverse and longitudinal uniformity can be affected by:
• radiation damage of scintillator material
• radiation damage of fibres
σE
E
ECAL
E
upgrade workshop Jan 07
GeV
5
Andreas Schopper
ECAL scintillator degradation (CALO TDR)
Studies of ECAL scintillator
damage and annealing:
PSM-115 scintillator
Irradiation at LIL up to 5 Mrad
Irradiation rate: 10 rad/s
L=2x1032cm-2s-1 Æ 20 years
L=2x1033cm-2s-1 Æ 2 years
(Shower Max at 42cm inside module)
upgrade workshop Jan 07
Andreas Schopper
6
ECAL fibers degradation (CALO TDR)
Y11 fibres
Studies of ECAL WLS fibers
damage and annealing:
Irradiation at LIL up to 5 Mrad
Irradiation rate: 10 rad/s
L=2x1032cm-2s-1 Æ 20 years
L=2x1033cm-2s-1 Æ 2 years
(Shower Max at 42cm inside module)
upgrade workshop Jan 07
Andreas Schopper
7
ECAL performance degradation (CALO TDR)
Simulation study of ECAL response using expected longitudinal dose profile
and measured degradation of scintillator and fibres material:
1) Loss of module light yield
8 years at 2x1032 Æ 2 Mrad Æ ~30% loss
2 years at 2x1033 Æ 5 Mrad Æ ~60% loss
(In 2000 we have assumed the
light yield of 1000 p.h.e/GeV:
Measured value ~4000 p.h.e./GeV)
2) Degradation of Energy resolution
σ(E)/E ~ 1.3% for 100 GeV for 0 Mrad
σ(E)/E ~ 1.7% for 100 GeV for 2 Mrad
σ(E)/E ~ 3% for 100 GeV for 5 Mrad
3) Degradation of constant term
upgrade workshop Jan 07
Andreas Schopper
8 years at 2x1032 Æ 2 Mrad Æ ~ 1.5% (!)
2 years at 2x1033 Æ 5 Mrad Æ ~ 3%
(conservative estimation, annealing was
not taken into account)
8
ECAL dose (Mrad) after 1 year at L=2x1033cm-2s-1
(thanks to Ivan Korolko)
Following TDR criteria
we have to change
16 inner modules (9%)
after 1 year of operation
(dose of 2 Mrad)
(modules with red cells
have to be changed)
upgrade workshop Jan 07
Andreas Schopper
9
ECAL dose (Mrad) after 3 years at L=2x1033cm-2s-1
Following TDR criteria
we have to change
84 inner modules (47%)
after 3 years of operation
In 3 years the constant
term (energy resolution)
for innermost modules
will degrade to >3%
upgrade workshop Jan 07
Andreas Schopper
10
ECAL dose (Mrad) after 5 years at L=2x1033cm-2s-1
Following TDR criteria
we have to change
136 inner modules (77%)
after 5 years of operation
After 5 years the innermost
modules will be dead
upgrade workshop Jan 07
Andreas Schopper
11
Some conclusions on ECAL
1) After 3 years of operation at high luminosity we have to change almost
50% of inner ECAL modules. Part of them will be seriously damaged
(>3% constant term).
2) Current support structure does not allow us to perform this change.
3) Dismantling and reconnection of monitoring system is an issue.
4) Degradation of HV system (CWs) and PMTs would have to be studied.
upgrade workshop Jan 07
Andreas Schopper
12
Preshower dose (Mrad) after 5 years at L=2x1033cm-2s-1
SPD and Preshower will
collect significant dose...
Degradation would have to
be studied!
Scintillator of PS/SPD
=polymerized technique
=less radiation hard
as compared to
ECAL/HCAL
=molded injection technique
=more radiation hard
upgrade workshop Jan 07
Andreas Schopper
13
Hadronic Calorimeter
(CALO TDR)
Optical components under irradiation:
PSM-115 scintillator
0.9
Longitudinal dose in the LHCb HCAL
1
• non irradiated
• 500 krad
• 1 Mrad
0.9
0.8
•400 krad
• 1.1 Mrad
0.6
0.8
0.7
0.5
0.2
0.5
0
2
4
=> max of
50 krad/y
40000
30000
20000
0
1
6
8
10
One day after irradiation
12
14
16
cm
0.3
0
20
40
60
80
100
120
Attenuation in fibre vs. distance to PM
140
(cm)
Degradation of light yield after irradiation at 70 GeV PS at
Serpukhov with 70 krad/day up to a total dose of 1.5 Mrad
=> scintillator -20%, fibres -15% for 500 krad
or 1y at 2x1033 (no annealing observed)
upgrade workshop Jan 07
14
2
3
4
5
6
HCAL section
Closest to the beam module
0.4
0.1
0
50000
10000
Annual dose (rad)
0.3
60000
0.6
81krad
162krad
272krad
400krad
1140krad
1560krad
0.4
Annual dose (rad)
1
relative light yield (a.u.)
Relative LY as a function of distance from source to fiber
0.7
Simulation of expected
radiation profile at L=2x1032
Y11 fibres
60000
50000
40000
30000
20000
10000
0
1
2
3
4
Next module
Andreas Schopper
5
6
HCAL section
Hadronic Calorimeter
Performance under irradiation:
Simulation study of HCAL response using
expected longitudinal dose profile and
measured degradation of scintillator and fibres
material.
For an accumulated dose of 500 krad (1year at
L=2x1032) one expects an increase of the
constant term from 10% to 12%.
Conservative estimate, since higher dose rate at
Serpukhov than at LHC, but uncertainties in
expected doses.
Simulation for 1 Mrad (2years) shows
degradation of constant term to 15%.
(MC)
10
2
10
non irradiated
=> HCAL modules operational for trigger at1
least 2 years even for the inner most cells
0
20
But: Degradation of HV system and PMTs to be investigated!
upgrade workshop Jan 07
15
40
60
80
100
120
Calibrated Light collection (at 80 GeV)
Andreas Schopper
140
160
(GeV)
What if the readout is performed at 40 MHz
or at 1 MHz with 40 times more FE-storage?
¾ Required latency of 160 microsecond
9 Calo readout has a maximum of 6.4 microsecond latency
¾ Replace all FE boards of ECAL/HCAL
¾ Replace all Preshower (PS+SPD readout)
¾ Replace backplane of all FE crates
9 PS and SPD VFE already functioning at 40 Mhz
¾ Occupancy spill-over?
¾ PMT current?
upgrade workshop Jan 07
16
Andreas Schopper
Which groups are interested in an upgrade?
¾ None of the calorimeter groups have declared interest in investing manpower
and/or money for upgrade at the present time!
¾ It is felt that full priority should go into putting the currently built detector
into operation by end of 2007 with best possible performance.
¾ Up to 2009 resources of manpower in the calorimeter groups are overcommitted, for completing the commissioning phase in 2007 and for starting
the first operation phase in 2008. Thereafter some R&D on e.g. improved
shashlik technology could be envisaged ( improved E-resolution, improved
granularity, improved radiation hardness…).
upgrade workshop Jan 07
17
Andreas Schopper
Summary for Calorimeters
At 2x1033 luminosity and 40 MHz readout:
¾
All FE electronics would have to be replaced
¾
50% of inner ECAL modules will have a constant term worse than 1.5% and
up to ~3%
¾
Preshower degradation would have to be investigated
¾
HCAL modules probably operational for 2 years with constant term ~15%
¾
No manpower available for any R&D up to 2009
¾
Once detector fully operational and stable, some R&D towards improved
ECAL (even for standard running conditions) could be envisaged
upgrade workshop Jan 07
18
Andreas Schopper