Transcript Document

Super LHC - SLHC
LHC Detector Upgrade
Dan Green
Fermilab
SLHC Trigger Workshop – Feb. 13, 2004
1
Outline
Physics Basics
Z’ vs , s
Rapidity Range
Minbias
Pileup and Jets
CERN-TH/2002-078
“Physics Potential and
Experimental
Challenges of the LHC
Luminosity Upgrade”
[10x will be challenging]
Occupancy and Radiation Dose
Tracker Upgrade
Calorimetry
Muons
Trigger and DAQ
SLHC Trigger Workshop – Feb. 13, 2004
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Mass Reach vs L
N=100 Events, Z' Coupling
VLHC
2 TeV
10
14 TeV
4
28 TeV
LHC
MZ'(GeV)
100 TeV
Tevatron
10
3
10
32
10
33
10
34
10
35
Luminosity(/cm2sec)
The SLHC defines a decades long LHC Physics program. In general mass reach is
increased by ~ 1.5 TeV for Z’, heavy SUSY squarks or gluinos or ~ 20% of extra
dimension mass scales. A ~ 20% measurement of the HHH coupling is possible for Higgs
masses < 200 GeV. However, to realize these improvements we need to maintain the
capabilities of the LHC detectors.
SLHC Trigger Workshop – Feb. 13, 2004
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Kinematics
5 TeV
1 TeV
d / dy
barrel
y
barrel
Heavy States decay at wide angles. For
example Z’ of 1 and 5 TeV decaying into
light pairs. Therefore, for these states we
will concentrate on wide angle detectors.
SLHC Trigger Workshop – Feb. 13, 2004
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Detector Environment
LHC
s
L
 Ldt
SLHC
14 TeV
14 TeV
2
1034 /(cm  sec) 1035 /(cm2  sec)
100 fb1 / yr 1000 fb1 / yr
Bunch spacing dt
25 ns
12.5 ns
N( interactions/x-ing)
~ 12
~ 62
dNch/d per x-ing
Tracker occupancy
Pile-up noise
Dose central region
~ 75
1
1
1
~ 375
5
~2.2
10
Bunch spacing reduced 2x. Interactions/crossing
increased 5 x. Pileup noise increased by 2.2x if
crossings are time resolvable.
SLHC Trigger Workshop – Feb. 13, 2004
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Pileup and Luminosity
For  I ~ 50 mb, and c = 6 charged pions/unit
of y with a luminosity  1035 / cm2  sec
and a crossing time of 12.5 nsec :
5 x109 int/ sec
62 int/ x  ing
375   / x  ing , unit of y
In a cone of radius = 0.5 there are ~ 70 pions, or
~ 42 GeV of transverse momentum per
crossing. This makes low Et jet triggering and
reconstruction difficult.
SLHC Trigger Workshop – Feb. 13, 2004
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WW Fusion and “Tag Jets”
Pileup, R=0.5, |y|=3
These jets have
ET ~ MW / 2
~ pileup R = 0.5 and <y>
~ 3. Lose 5x in fake
rejection. We must use
the energy flow inside a
jet cone to further reduce
the fake jets due to pileup
(~ uniform in R).
WW
fusion
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Tracking Detectors
Clearly, the tracker is crucial for much of the
LHC physics [e.g. e, , jets (pileup, E flow), b
tags].
The existing trackers will not be capable of
utilizing the increased luminosity as they will
be near the end of their useful life.
It is necessary to completely rebuild the LHC
tracking detectors.
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Tracker - Occupancy
The occupancy, O, for a detector of area
dA and sensitive time time dt at (r,z) is
O   I c (dAdt ) /[2 r ]
2
e.g. Si strip 10 cm x 100 m in a 12.5 nsec
crossing at r = 20 cm is 1.5 %
For higher luminosity, decrease dA, or
decrease dt (limit is x-ing time) or
increase r – smaller, faster or further
away.
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Tracker Occupancy
Preserve the performance using 1/ r 2 :
Push Si strips out to ~ 60 cm. – development
Push pixels out to 20 cm. – development
For r < 20 cm. Need new technologies – basic
research
Shrink dA 5x at fixed r to preserve b tagging?
If 12.5 nsec bunch x-ing, need 5x pixel size
reduction.
Possibilities
3-d detectors – electrodes in bulk columns
Diamond (RD42) - radhard
Cryogenic (RD39) – fast, radhard
Monolithic – reduced source capacity.
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Tracker ID vs. Radius
35
10
Ionizing Dose in Tracker for 10
3
1
naive
Dose(Mrad)
10
10
10
10
2
L and 1 Year
3
2
1
0
-1
10
0
10
1
10
2
10
3
r(cm)
Define 3 regions. With 10x
increase in L, need a ~ 3x
change in radius to preserve
an existing technology. The
2
ID scales as ~  / r
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Electronics – Moore’s Law
10m
P. Sharp
Industry
1m
Research
0.1m
1985
2000
SLHC Trigger Workshop – Feb. 13, 2004
Micro-electronics: line-widths
decrease by a factor 2 every 5 years.
DSM (0.25 m) is radiation
hard.Today 0.13 m is commercially
available. In the lab 0.04 m, e.g.
extreme UV lithography, is in
existence. Expect trend will continue
for a decade.
R&D
Characterize emerging technologies
more radiation tolerance required –
dose and Single Event Effects
advanced high bandwidth data link
technologies
system issues addressed from the
start
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HCAL and ECAL Dose
35
10
Dose in ECAL and HCAL for L = 10 and One Year
3
ecal
10
2
hcal
Dose(Mrad)
naive
10
10
10
10
1
0
-1
-2
0
1
2
3
4
5

The dose ratio is ~ Eth (  p      p) / Ec . Barrel
doses are not a problem. For the endcaps a
technology change may be needed for 2 < |y| < 3 for
the CMS HCAL. Switch to quartz as in HF? SD ~
ID/sin.
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HCAL - Coverage
Reduced forward coverage to
compensate for 10x L is not too
damaging to “tag jet”
efficiency, SD ~ 1/3 ~ e3
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Scintillator - Dose/Damage
|y|=2, 1 yr.
Scintillator under irradiation forms
Color centers which reduce the
Collected light output (transmission loss).
LY ~ exp[-D/Do], Do ~ 4 Mrad
This technology will not
survive gracefully at |y| ~
3. Use the technology
that works at LHC up to
|y|~ 5, quartz
fibers/plates ?
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Muons and Shielding
There is factor ~
5 in headroom
at design L.
With added
shielding, dose
rates can be
kept constant if
angular
coverage goes
from |y|<2.4 to
|y|<2.
r
n /(cm2 sec)
r
z
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Trigger and DAQ
Assuming LHC initial program is successful,
raise the trigger thresholds?
Rebuild trigger system to run at 80 MHz?
Utilize those detectors which are fast enough to
give a BCID within 12.5 nsec (e.g. Calorimetry,
Tracking, Muon?).
Examine algorithms to alleviate degraded e
isolation, for example.
Design for the increased event size (pileup) with
reduced L1 rate and/or data compression.
For DAQ track the evolution of communication
technologies, e.g. 10 Gb/sec Ethernet.
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Level-1 Trigger Table (2x1033)
Steeply falling spectra. Use muons and calor only? Jets and
muons ~ clean  HLT is resolution on spectral “edge”
Trigger
Threshold
(GeV)
Rate (kHz)
Cumulative
Rate (kHz)
Isolated e/g
29
3.3
3.3
Di-e/g
17
1.3
4.3
Isolated muon
14
2.7
7.0
3
0.9
7.9
Single tau-jet
86
2.2
10.1
Di-tau-jet
59
1.0
10.9
177, 86, 70
3.0
12.5
Jet*ETmiss
88*46
2.3
14.3
Electron*jet
21*45
0.8
15.1
0.9
16.0
Di-muon
1-jet, 3-jet, 4jet
Min-bias
TOTAL
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16.0
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Level-1 Trigger Table (1034)
Trigger
Threshold
(GeV or GeV/c)
Rate (kHz)
Cumulative
Rate (kHz)
Isolated e/g
34
6.5
6.5
Di-e/g
19
3.3
9.4
Isolated muon
20
6.2
15.6
5
1.7
17.3
101
5.3
22.6
67
3.6
25.0
250, 110, 95
3.0
26.7
113*70
4.5
30.4
Electron*jet
25*52
1.3
31.7
Muon*jet
15*40
0.8
32.5
1.0
33.5
Di-muon
Single tau-jet
Di-tau-jet
1-jet, 3-jet, 4-jet
Jet*ETmiss
Min-bias
TOTAL
33.5
L1 Trigger on leptons, jets, missing ET and calib/minbias.
Does this suite cover all the Physics we want?
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L1 at 1035 ?
Muons are ~ clean.
Issue of low
momentum muons

from b jets. Jets are ~
clean. ECAL jets are
mostly “garbage”   
need tracker to make
big L1 improvements. J
Rutherford scattering
~ 1/PT3.
J*MET
SLHC Trigger Workshop – Feb. 13, 2004
1034
1035
20
40
5
7.5
250
540
113*70
170*100
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Higgs Self Coupling
Baur, Plehn, Rainwater
HH  W+ W- W+ W-   jj jj
Find the Higgs? If the H mass is known, then the SM H
potential is completely known  HH prediction. If H is
found, measure self-couplings, but ultimately SLHC is
needed.
CMS will not, in all scenarios, be moving to higher masses.
Sometimes rarer processes must be measured at the same
mass scale.
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HLT Summary: 2x1033 cm-2s-1
Trigger
Threshold
(GeV or GeV/c)
Rate (Hz)
Cuml. rate (Hz)
Inclusive electron
29
33
33
Di-electron
17
1
34
Inclusive photon
80
4
38
40, 25
5
43
19
25
68
7
4
72
Inclusive tau-jet
86
3
75
Di-tau-jet
59
1
76
180 * 123
5
81
657, 247, 113
9
89
Electron * jet
19 * 45
2
90
Inclusive b-jet
237
5
95
10
105
Di-photon
Inclusive muon
Di-muon
1-jet * ETmiss
1-jet OR 3-jet OR 4jet
Calibration etc
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TOTAL
105
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HLT Performance — Efficiency
Channel
Efficiency
(for fiducial objects)
H(115 GeV)gg
77%
H(160 GeV)WW* 2
92%
H(150 GeV)ZZ4
98%
A/H(200 GeV)2
45%
SUSY (~0.5 TeV sparticles)
~60%
With RP-violation
~20%
We
67% (||<2.1, 60%)
W
69% (||<2.1, 50%)
t X
72%
Gains in HLT? Tracker (pixel) biggest gain for e.
Single muon and electron still the highest rates.
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Level-1 Trigger
Trigger Menus
Triggers for very high pT discovery physics: no rate problems –
higher pT thresholds
Triggers to complete LHC physic program: final states are known –
use exclusive menus
Control/calibration triggers with low thresholds (e.g. W, Z and top
events): prescale
Impact of Reduced Bunch Crossing Period
Advantageous to rebuild L1 trigger to work with data sampled at 80
MHz ? Work out the consequences
Require modifications to L1 trigger and detector electronics
Could keep some L1 trigger electronics clocked at 25 ns?
R&D Issues
Data movement is probably the biggest issue for processing at 80
MHz sampling
Processing at higher frequencies and with higher input/output data
rates to the processing elements. Technological advances (e. g. FPGA )
will help
Synchronization (TTC) becomes an issue for short x-ing period
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HCAL Timing
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Summary
The LHC Physics reach will be substantially
increased by the higher luminosity of the SLHC
program.
To realize that improvement, the LHC
detectors must preserve performance.
The trackers must be rebuilt – with new
technology at r < 20 cm.
The calorimeters, muon systems, triggers and
DAQ will need development.
The upgrades are likely to take ~ (6-10) years.
Accelerator is ready ~ (2012, 2014). The time to
start is now.
The work on the SLHC for CMS are beginning.
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