Feasibility study of a Level-1 track
trigger for ATLAS at Super-LHC
Véronique Boisvert, RHUL
PPRP meeting, Glasgow June 24th 2009
For:
A. Affolder, P. Allport, V. Boisvert, D. Costanzo, G. Crone, A. De Santo, B.
Green, A. Greenall, N. Konstantinidis, M. Lancaster, A. Misiejuk, F.
Salvatore, M. Sutton, P. Teixeira-Dias, M. Warren
Outline
Motivation for SLHC
Motivation for a Level-1 Track Trigger
Time scales and ATLAS organization
Status of current work on the Level-1
Track Trigger
The proposal
Response to referees comments
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Physics Motivations for SLHC
 SLHC is a luminosity upgrade to the LHC
 Extend discovery sensitivity
 Pin down the theory beyond the Standard
Model
 Relatively modest investment to extend LHC capabilities
 In more details: (from hep-ph/0204087)
 1. Improvement of the accuracy in the determination of SM parameters
(TGC, QGC, Higgs couplings)
 2. Improvement of the accuracy in the determination of parameters of
New Physics possibly discovered at the LHC (e.g. sparticle
spectroscopy, tan measurements)
 3. Extension of the discovery reach in the high-mass region (e.g. quark
compositeness, new heavy gauge bosons, etc)
 4. Extension of the sensitivity to rare processes (e.g. FCNC top decays,
Higgs-pair production, multi gauge boson production)
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Physics Motivation for a Level-1
Track Trigger
 Conclusions from 2002 physics studies:
 1. Most signatures require more than 1 leptons
 2. pT requirement is low: 20GeV, ||<2.5
 3. Total efficiency is assumed to be 90%
 4. A lot of results are at the limit of what the SLHC can offer
 E.g. need 6000fb-1 to achieve 5
 Implication:
 Need to retain the capability of triggering on objects at the
electroweak scale in the harsh SLHC environment
 Is a Level-1 Track Trigger the answer?
• In current system, tracking information is essential to the performance
of Level-2 trigger
• It would add flexibility to the system
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Time scales and ATLAS upgrades
Machine
ATLAS
LoI: Q2 2010
LHC: run for 8-10 years
design luminosity: 1034cm-2s-1
25ns bunch crossing
23 proton collisions
/bunch crossings
SLHC Phase-I: ~2014
Peak luminosity:
2-3x1034cm-2s-1
UK
2010
2011
TP: 2011/12
2012
Tracker TDR:
2012/13
2013
2014
Level-1 Calo/Muon
upgrade
2015
L1 TrackTrigger proposal
until 30th June 2010
ATLAS upgrade
full proposal
2010-2013
-Tracker
- TDAQ
- incl. Track Trigger
- Computing
2016
18 months shut down
SLHC Phase-II: ~2018
Peak luminosity: 1035cm-2s-1
25ns or 50ns bunch crossing
200-400 proton
collisions/bunch crossings
Particle flux about 20
times higher than LHC
Veronique Boisvert, RHUL
2017
Replace inner detector
with all-silicon tracker
Readout electronics
Trigger system
2018
5
Level-1 Track Trigger organization
ATLAS wide
 Non-UK members working or interested in the project:
 USA: U. of Chicago, U. of Pennsylvania, U. of Indiana, +
tracker upgrade institutes, e.g. Berkeley, Santa Cruz
 Japan: Tokyo, KEK, Kobe
 Sweden: U. of Uppsala
 Germany: Heidelberg U.
 Work Packages in view of the ATLAS upgrade Letter of
Intent
 WP1: Simulation/performance/algorithms
 WP2: on-detector electronics
 WP3: data transmission
 WP4: off-detector electronics
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Status of current work on the Level-1
track trigger
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Current ATLAS trigger system
40 MHz
1 kHz
1 sec
200 Hz
Region of
Interest RoI
2.5 ms
SLHC: ~6 ms?
10 ms
Rate
Level 1
trigger
High Level Trigger
100 kHz
L1 Track Trigger
Level 2
trigger
Event
Filter
Latency
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Level-1 Track Trigger Options
 Impossible to fully read out the tracker for Level1
2 classes of options:
 Dedicated trigger layers
• CMS choice
 Regional readout (Region of Interest based)
• Within Level-1 latency:
 Tracking based on L1Calo/Muon input (L0A)
• Outside Level-1 latency:
 On L1A, data moves to buffers but does not get read out until
further command issued a few ms later (L1.5, “fast-clear”)
 If very large buffers on the Front-Ends, RoI processing
approaches current Level-2
 Whatever option
Consequences for the tracker electronics are significant
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Dedicated layers option
 Build double layers to look for
coincidences (remove stereo
angle functionality)
 Efficiency to have 1 coincidence
with single electron or muon of
20/30GeV within 400 min bias
events is high (~85%)
 Data rates: eg. 500
coincidences x 10
bits/coincidence x 40MHz =
200Gb/s /layer
Barrel
400 pile-up
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Coincidences per event
Coincidence layer
Stereo angle
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E.g. for layer 5: 700
coincidences
correspond to 25%
occupancy
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Regional readout options
 Studying:
Size of RoI
How often is a module in a
Region of Interest?
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Barrel strip layer
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Regional readout options
 Studying:
On detector data reductions:
 Clustering done in the Front-end:
about factor of 2 smaller data
size
 Reject wide clusters: ~30%
reduction
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Data flow latency
Preliminary estimates come up with about 4.2ms for the track trigger
(data transfer + processing)
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Other current activities
Using 1034/1035 simulation
Rate studies to evaluate need and estimated
performance of Level-1 track trigger
Simulating upgraded L1Calo/Muon by using
current Level2 algorithms
Using upgraded-tracker-only simulations to
study the various track trigger options
Getting involved/providing input to the physics
for SLHC group
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The proposal
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Members
PI: Dr Nikos Konstantinidis (UCL)
FTE: 20%
Institutes:
Sussex
UCL
PI: Dr Antonella De Santo
PI: Dr Nikos Konstantinidis Total FTE: 40%
Liverpool
Total FTE: 80%
PI: Prof Phill Allport
RHUL
Total FTE: 15%
PI: Dr Veronique Boisvert
Sheffield
Total FTE: 55%
PI: Dr Davide Costanzo
Total FTE: 10%
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Objectives and milestones
 Milestones:
M1: provide feedback and L1Track requirements to the
tracker layout task force
 By Q4/2009
M2: provide a baseline design for L1Track for the ATLAS
LoI
 By Q2/2010
 Objectives for next 12 months
1. Develop/optimise tools for studying simulated events
with large pile-up
2. Study alternative designs for L1Track
3. Investigate pattern recognition algorithms and offdetector L1Track electronics
4. Study trigger rates and efficiencies at 1035cm-2s-1 and
evaluate the benefits of L1Track
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Costs
 All efforts are from existing Rolling Grant funded posts
and FTE fractions are in line with current grants and
grants currently applied for
 A little bit of “new money” for Sussex due to new
academic appointments
 E&I costs for 01/07/09 to 30/09/09
 Travel
 5 UK meetings at average cost of 50GBP/person and 8
travelers per meeting, total: 2kGBP
 40 international trips (10 travelers, 2 ATLAS upgrade weeks,
2 ATLAS TDAQ workshops) at 500GBP per trip, total:
20kGBP
 To be administered centrally by RAL-PPD
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Costs
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Response to referees comments
 Clarification on PI:
Dr Nikos Konstantinidis, 20% FTE, co-leader of the ATLAS
wide Level-1 Track Trigger effort, will be on sabbatical at
CERN for next 18 months.
 International context and partnerships
See previous list of international partners on ATLAS
Strong ties on this project with Level-1 Calo/Muon:
 Most Level1-Calo expertise is in UK and already work closely
with members
 Level1-Muon institutions are involved at ATLAS level with the
project
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Response to referees comments
 Project management
Project will last 12 months and involves few members,
so light structure is appropriate
 Working meetings once a month
 PIs of each institute will discuss at the end of each
meetings to address any necessary management action
 Sharing of tasks between members
Bulk of FTE on UCL, RHUL and Sussex
Liverpool and Sheffield consultancy is essential since
involved in tracker upgrade and simulation work
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Response to referees comments
 Project timescales and long term planning
This proposal only covers next 12 months:
 To look at need for Level-1 Track Trigger
 To come up with baseline design for the ATLAS LoI
In process of writing a 3 year proposal (2010-2013) for
which there will be additional resources needed to come
up with a more detailed design and possibly a prototype
 Travel funds
Members will be efficient with overlap with ATLAS
meetings
Upgrade meetings not covered under ATLAS travel
Sussex does not have ATLAS travel
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Response to referees comments
Premature to talk about ATLAS upgrade?
Current ATLAS silicon tracker took 10 years
from TDR to completion of construction
Estimate that for upgraded tracker fastest would
be 5 years
If want to run upgraded ATLAS by ~2020, then
need TDR by 2014 at the latest (allowing 1 year
of procurement)
Need all R&D, qualification and pre-series
studies to happen before then
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Conclusions
Every experiment that built a hardware track
trigger (H1, ZEUS, CDF, …) highly benefited
from it
The UK currently has leadership in the
project
We have the leadership and technical skills to
become an important player of this important
upgrade activity
This proposal is the first step along that road
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Backup slides
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Nessi, 09/06/09
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Examples relevant to L1Track Trigger
 1. Multiple Gauge boson
production
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 Studies assume:
 90% id efficiency for each
lepton
 |l|<2.5, PTl>20GeV
 2. Hmm:
 LHC: not better than 3.5
 Study assumes:
 90% id efficiency for each
muon
 |l|<2.5, PTl>20GeV
Veronique Boisvert, RHUL
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Examples relevant to L1Track Trigger
 3. Top FCNC
 tq:
 1 iso.  ET>75GeV, ||<2.5
 1 l pT>20GeV, ||<2.5
 Jets
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 tqg:
 1 l pT>20GeV, ||<2.5
 Jets
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 tqZ:
 3 l pT>20GeV, ||<2.5
 Jets
 4. SUSY: Point K
 Meff = ETmiss +  ETjet +  ETlepton
 lepton ET>15GeV
Veronique Boisvert, RHUL
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Examples relevant to L1Track Trigger
LHC 10fb-1
 5. ED in RS model
LHC 100fb-1
 Gll
SLHC 1000fb-1
 Conclusions from examples:
 1. Most signatures require >1 leptons
 2. Offline pT cut is always >20GeV, ||<2.5
 Don’t know dependence of results vs pT,  cut
 L1 Track Trigger will have to be both barrel and endcap
 3. Total efficiency is assumed to be 90%
 Don’t know dependence of results vs efficiency
 4. A lot of results are at the limit of what the SLHC can offer
 E.g. need 6000fb-1 to achieve 5
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Trigger Strategy at SLHC
 Very high pT for discovery physics
 Low pT thresholds but then use multi-objects or
exclusive (1 el + MET + N jets) triggers
Can we achieve this? What impact does this have on
physics goals?
 Prescaled control/calibration triggers
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From scaling of L1 TDR, does not take into
account full pile-up or cavern background
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L1 Muon
 One of the reasons for CMS
getting L1 Track trigger is
flatness of L1 muon rate
Kawamoto, 13/11/08
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 See e.g. arXiv:0810.4133
 Turns out ATLAS is also
pretty flat
 But feasible solutions
related with adding layer to
Muon
 Note that this is meant to
address how the rate should
be falling with pT thresholds
 But ideally we don’t want to
raise those!
 Absolute rate will decrease by
how much?
Veronique Boisvert, RHUL
Mikenberg, 26/02/09
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Time scales and ATLAS upgrades
Machine
LHC: run for 8-10 years
design luminosity: 1034cm-2s-1
25ns bunch crossing
ATLAS
LoI: April 2010
TP: 2011/12
Tracker TDR:
2012/13
SLHC Phase-I: ~2014
Peak luminosity: 2-3x1034cm-2s-1
Level-1 Calo/Muon
upgrade
UK
L1 TrackTrigger proposal
until 30th June 2010
ATLAS upgrade
full proposal
2010-2013
-Tracker
- TDAQ
- incl. Track Trigger
- Computing
18 months shut down
SLHC Phase-II: ~2018
Peak luminosity: 1035cm-2s-1
25ns or 50ns bunch crossing
200-400 proton collisions/bunch crossings
Particle flux about 20 times higher than LHC
Veronique Boisvert, RHUL
Replace inner detector
with all-silicon tracker
Readout electronics
Trigger system
40