cms upgrade issues

CMS Upgrade Issues

SPC 15 September 2008

SPC - 15/9/20081 J. Nash - CMS SLHC Issues

Topics Potential Physics motivations

Implications for the detectors Tracking detectors

Requirements for phase I Requirements for phase II Tracking Trigger

Muons and Calorimeters Implications for the detector of Upgrades

which place machine elements inside 19m

SPC - 15/9/2008J. Nash - CMS SLHC Issues 2


SLHC is about the maximizing the output of LHC physics We should be led by getting the best physics

out of any upgraded machine/detector Not by the highest peak luminosity Even maximum integrated luminosity may not be

the most important metric Issues

Integrated luminosity Backgrounds Acceptance Pile-up

Collimation phase 2

Linac4 + IR

upgrade phase 1

New injectors

+ IR upgrade phase 2

Early operation


What are the key timescales/issues? Phase 1

How well do detector components handle the increasing luminosity? Both instantaneous and integrated effects

What detector elements will need replacement/modification to cope? Detectors will record >500 fb-1, can they withstand this?

Phase 2 What detector elements will need replacement? What do machine plans imply for interaction regions Is there a requirement for a long shutdown?

How long – 18 Months? (1 Full calendar year without beam +) When – sometime after the middle of the next decade

Developing and building new tracking detectors will take many years We have to plan this now in order to have any chance of running detectors

with high luminosity ATLAS and CMS now agree on the dates

No sense in having two long shutdowns Reach 700 fb-1(potential limit)

Likely 2017


Issues discussed at the CMS May Upgrade workshop What are the “strawmen” for upgrades of

each of the systems? Define the scope of the upgrade projects What is done in Phase I/Phase II

What requires a long shutdown? What can/should we attempt to do before the long

shutdown How should we use the lengthy shutdown in 2013?

When do we need to prepare a LOI For CMS Upgrades For subsystems

When do we need to prepare TDRs


http://indico.cern.ch/conferenceDisplay.py?confId=28746http://indico.cern.ch/conferenceDisplay.py?confId=28746


Some Physics themes Different physics channels require different

conditions Three main directions for Phase II

Damn the torpedos - FULL Luminosity Maximum of quality luminosity

Luminosity leveling? Forward acceptance

We won’t know which is the most important until we have first data from the LHC Important not to eliminate a physics opportunity until

we are sure it makes sense to do so We have to be ready to build detectors for any of

these scenarios


SLHC Physics: Extra gauge bosons

SLHC extends reach for Z’ Cross sections fall with E SLHC gives access to higher E

Good electron resolution required (including understanding saturation)

Just give us the Integrated Luminosity!Just give us the Integrated Luminosity!


SUSY searches - measurements

SLHC statistics will be vital in reaching understanding of complicated SUSY channels Sparticles seen, but statistics

for reconstruction limited at LHC

Performance of the detector here is vital B-tagging Lepton id

Here we need a lot of Integrated Luminosity, but needs to be high quality. Lower pile-up may be important.

Here we need a lot of Integrated Luminosity, but needs to be high quality. Lower pile-up may be important.

PixelsPixels

J. Nash - CMS SLHC Issues

The pixel 3D hits are ideal seeds for tracking and reconstruction Pattern recognition, all 5 track parameters well constrained

• Excellent position resolution makes pixels essential :

• for primary and secondary vertex reconstruction

• for b and identification

Dark matter candidateSPC - 15/9/200811


What if no Higgs is found?

Will need to look at WW scattering Some mechanism required to avoid

unitarity violation Forward Jet Tagging Essential

3000 fb-1 (SLHC)

Fake fwd jet tag (|| > 2) probability from pile-up (preliminary ...)

ATLAS full simulation

Forward tagging is essentialForward tagging is essential

SPC - 15/9/2008 J. Nash - CMS SLHC Issues 13

Higgs Boson Couplings

Ratios of Higgs couplings to fermions and gauge bosons Independent of uncertainties on tot

Higgs, H and integrated luminosity

Mostly statistics limited at the LHC

Some modes are systematically limited at LHC luminosities - no improvement at SLHC

Some modes are systematically limited at LHC luminosities - no improvement at SLHC

HHZZ

HWWHZZ

WHH

ttH/ttHbb

qqHWWqqH

WHWWWHWW


Precision Electroweak meaurements

5 parameters describe these TGCs: g1

Z (1 in SM), z, , z(all 0 in SM)

Look in W I , WZ lll W final state probes , WZ probes g1

Z, z, z

Experimental precision can reach 10-3 level at SLHC Compares to SM prediction level

Z

kZ

Z

14 TeV 100 fb-1 28 TeV 100 fb-1 14 TeV 1000 fb-1 28 TeV 1000 fb-1


Extending MSSM searches, Rare Decays

• rare modes not observable at the LHC HSM Z (BR ~ 10-3), HSM (BR ~ 10-4)

HSM Z l+l- 120 < MH < 150 GeV, LHC with 600 fb-1 signal significance: 3.5 SLHC (two exps, 3000 fb-1each) signal of 11HSM 120 < MH < 140 GeV, LHC (600 fb-1) significance: < 3.5,

SLHC (two exps, 3000 fb-1each) ~ 7

LHC 300 fb-1LHC 300 fb-1

SLHC 3000 fb-1SLHC 3000 fb-1

Can extend region where more than one Higgs is seen (in MSSM)


Detector ChallengesCMS from LHC to SLHC

10331033

10351035

1032 cm-2 s-1 1032 cm-2 s-1

10341034

I. OsborneI. OsborneThe tracker is the key detector which will require upgrading for SLHC Phase 2

The tracker is the key detector which will require upgrading for SLHC Phase 2


Radiation environment for trackers

R. HorisbergerR. Horisberger

Except for the very innermost layers many current technologies should survive SLHC

Except for the very innermost layers many current technologies should survive SLHC

CMS Pixel system can be removed in a very short time period


Trial insertion of Pixel system


Insertion of the Pixel was done in a fewhours

Insertion of the Pixel was done in a fewhours

Phase I issues for tracking Rough estimate of pixel layer lifetimes

4cm layer should survive a minimum of 200fb-1

Will have to replace the pixel detector during phase I How often? How much to replace? New features

Looking at reducing the material in the replacement pixel detector, and potentially adding a fourth layer

Outer tracker looks robust to survive Phase I


Limitations in Phase 1Limitations in Phase 1 Radiation damage due to

integrated luminosity. Sensors designed to survive

61014neq/cm2 ( 300 fb-1 ). n-on-n sensors degrade gradually

at large fluences

300 fb-1

500 fb-1


Dead time will rise to 12% due to increase in peak luminosity

BPIX Options for 2013 replacement/upgrade – R. Horisberger

Option

0

1

2

3

4

5

Cooling

C6F14

C6F14

CO2

CO2

CO2

CO2

Readout

analog 40MHz

analog 40MHz

analog 40MHz

analog 40MHz-tw-pairs

digital 320MHz-tw-pairs

digital 640 MHz-tw-pairs

Pixel ROC

PS46 as now

2x buffers

2x buffers

2x buffers

2xbuffer, ADC160MHz serial

2xbuffer, ADC160MHz serial

Layer/Radii

4, 7, 11cm

4, 7, 11cm

4, 7, 11cm

4, 7, 11cm

4, 7, 11cm

4, 7, 11, 16cm

Modules

768

768

768

768

768

1428

Power

as now

as now

as now

as now

as now

DC-DCnew PS

as 2

008



CMS - What stays, what goes phase 2

Much of CMS is well shielded andBuilt to last through SLHCMuch of CMS is well shielded andBuilt to last through SLHC

SPC - 15/9/2008


Reminder what CMS will need to upgrade

This will stay!This will stay!

Barrel crystal calorimterBarrel crystal calorimterHCALHCAL


Tracker Readied for Transport to Pt5This will be replacedThis will be replaced

SPC - 15/9/200825


Key issues for tracker upgrades(Not just more channels!)

Power How to get current needed to the electronics More complicated front ends, more channels may want more

power DC-DC converters, Serial powering

Material Budget Can we build a better/lighter tracker?

From Physics TDR Vol 1 (LHCC 2006-001)From Physics TDR Vol 1 (LHCC 2006-001)


The effect on physics of large pile-up We need to evaluate how well we can extract

any physics at all in the presence of up to 400 pile-up events per crossing

This is not a trivial study Technically difficult Also depends on geometry of a new tracking device Timescale for full answers is more like years than

months CMS Tracker simulation group has been

creating tools for modeling new tracker designs Expect detailed simulation results from “strawman”

designs in the coming year


Tracking with 500 min Bias events

Study of current CMS tracker for Heavy Ion events

Track density very similar to 50ns running dnch/d/crossing ≈ 3000 Tracker occupancy very high Need more pixel layers/shorter strips

Tracking possible When tracks are found they are well measured Efficiency and fake rate suffer CPU Intensive

nhit > 12

• Efficiencyo Fake Rate

Momentum Resolution

Transverse Impact

Parameter Resolution

C. RolandC. Roland

Inner layers of strips reach 30% occupancy on every xing!

Inner layers of strips reach 30% occupancy on every xing!

Pixel layersPixel layers


Level 1 Trigger

The trigger/daq system of CMS will require an upgrade to cope with the higher occupancies and data rates at SLHC

One of the key issues for CMS is the requirement to include some element of tracking in the Level 1 Trigger One example: There may not be

enough rejection power using the muon and calorimeter triggers to handle the higher luminosity conditions at SLHC

Adding tracking information at Level 1 gives the ability to adjust PT thresholds

Single electron trigger rate also suffers Isolation criteria are insufficient

to reduce rate at L = 1035 cm-

2.s-1

Level 1 Trigger has no discrimination for PT > ~ 20 GeV/c

Level 1 Trigger has no discrimination for PT > ~ 20 GeV/c

Tracking needed for L1 trigger@ 1035

Muon L1 trigger rate

Single electron trigger rate

Isolation criteria are insufficient to reduce rate at L = 1035 cm-2.s-1

5kHz @ 1035

L = 1034

L = 2x1033

MH

z

Standalone Muon trigger resolution insufficient

We need to get another x200

(x20) reduction for single

(double) tau rate!

Amount of energy carried by tracks around tau/jet direction

(PU=100)

Cone 10o-30o

~dET/dcos τ


Concepts:Tracking Trigger

Why not use the inner tracking devices in the trigger? Number of hits in tracking devices on each trigger is enormous Impossible to get all the data out in order to form a trigger How to correlate information internally in order to form

segments? Topic requiring substantial R&D

“Stacked” layers which can measure pT of track segments locally Two layers about 1mm apart that could communicate

Cluster width may also be a handle

SearchWindow

γ

Geometrical pT-cut - J. Jones, A. Rose, C. Foudas LECC 2005

High momentum tracks are straighter so pixels line up

High momentum tracks are straighter so pixels line up

Pairs of stacked layers can give a PT measurement

Pairs of stacked layers can give a PT measurement

Example PT module

Geoff HallVertex 200832

Such a design has potential for inexpensive assembly, using wire bonding, with low risk and easy prototyping

2 x 2.5mm

12.8mm64 x 2

Data out

128 x100µmx 2x2.5mm

Correlator

data

Pt - Trigger for TOB layers

2mm

Strip Read Out Chip2 x 100 pitch withon-chip correlator

Hybrid

50mm strips

1mm

2mm

2 x DC coupled Strip detectorsSS, 100 pitch ~8CHF/cm2

wire bonds

spacer

W.E. / R.H.

track angular resolution ~20mrad good Pt resolution

Two-In-One DesignR HorisbergerW Erdmann

33

Vertex 200834

More Realistic Strawman A A working idea from Carlo and Alessia

Take current Strawman A and remove 1 “TIB” and 2 “TOB” layers

Strawman A r-phi view Strawman A r-phi view

(RecHit ‘radiography’)(RecHit ‘radiography’)

4 inner pixels

2 TIB strixelsAdjust chn count

2 TIB short stripsRemove 1

2 TOB strixelsAdjust chn count

4 TOB short stripsRemove 2

Vertex 200835

More Realistic Strawman B Adjust granularity (channel count) of Strawman B layers

Keep the TEC for now until someone can work on the endcaps

Strawman B r-phi view Strawman B r-phi view (RecHit ‘radiography’)(RecHit ‘radiography’)

r-z view r-z view

Endcap CSC Muon Phase 1 Upgrade (ME4/2)

R-Z cross-section

“Empty” YE3 ready for ME4/2SPC - 15/9/200836 J. Nash - CMS SLHC Issues

Phase 1 : Muons ME4/2 upgrade motivation

Compare 3/4 vs. 2/3 stations: (Triggering on n out of n stations is inefficient and uncertain)

Recent simulation with & without the ME4/2 upgrade: The high-luminosity Level 1 trigger threshold is reduced from 48 18

GeV/c

Target Rate 5 kHz

Rick Wilkinson, Ingo BlochSPC - 15/9/200837 J. Nash - CMS SLHC Issues

The start up RPC endcap systemThe start up RPC endcap system

SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC groupgroup

Three stations up to = 1.6 Three stations up to = 1.6

RE 1/1

RE 1/2

RE 1/3

RE 2/1

RE 2/2

RE 2/3

RE 3/1

RE 3/2

RE 3/3

RE 4/1

RE 4/2

RE 4/3

No. of chambers 36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2

RE i/3

REi/2REi/1


RPC trigger efficiencyRPC trigger efficiency

SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC groupgroup

Trigger CMS TDR, four stations Importance of high restoration Importance of high restoration

CMSSW 1.7.5, three stations

Importance of four stations restoration Importance of four stations restoration



CMS HCALsHad Barrel: HB

Had Endcaps:HE

Had Forward: HF

HB

HE

HF

HO


HF Damage

Tower 1 loses 60% of light during LHC, down to 4% of original after SLHC.

Tower 2 down to 23% after SLHC.

SLHC “kills” a few high eta towers.

Andre Gribushin


Calorimeters/Muons Phase 2 ECAL

Crystal calorimeter electronics designed to operate in SLHC conditions

VPT in Endcap and Endcap crystals themselves may darken at SLHC Very difficult to replace – Highly

activated HCAL

HF may be blocked by potential changes to the interaction region

HF/HE vital in looking for WW scattering Both Calorimeters suffer degraded resolution

at SLHC affects electron ID, Jet resolutions –

simulations needed Increased segmentation for HCAL may

help – SiPM• MUON– system front end electronics look fairly robust at SLHC

• Cathode Strip Chambers/RPC Forward : Drift Tubes /RPC Barrel

• Trigger electronics for the muon systems would most likely need to be replaced/updated

– Some Electronics is “less” radiation hard (FPGA)– Coping with higher rate/different bunch crossing frequency

– May have to limit coverage in ( > 2) due to radiation splash

• This effect will be known better after first data taking, potential additional cost of chamber replacement

Upgrade Scope


Documents

Phase I Upgrades

Phase 2 Upgrades


Next Steps Produce an Integrated project plan for Phase I

Large number of systems expect to produce upgrades many of which involved interleaved installation issues

Some of these are already rather advanced and need to be integrated into the planning

Define timescales/scopes for reviews of each upgrade PDR > ESR/EDR > PRR?

Request milestones/deliverables down to level … for each project TDR > Production > Installation > Start to track these milestones

Will require resources


Planning for Phase 2 Too early for detailed planning of phase 2 upgrades Must understand the overall scope of the upgrade

This is driven by the geometry/functionality of the new tracker Simulations will be vital in understanding

Tracker TP should focus the direction of upgrades in other systems which may depend on tracker functionality For example the inclusion of tracking information in the trigger

Build a detailed plan by the time of the phase 2 TDRs Will also have a much clearer idea of the machine timescales

However a key issue which may come up earlier than this is the date of the long shutdown



Implications of Early Separation

Could we do this without replacing HF? No way without obscuring part of the

detector But perhaps lower eta region still usable

Will the HF still be useful at SLHC


What about maintenance?

These wheels move for maintenance

These wheels move for maintenance

Triplet moves closer to IPTriplet moves closer to IP

Either D0 has to clear the EE, or it has to move for

maintenance

Either D0 has to clear the EE, or it has to move for

maintenance

Forward beampipe

thin pipe 13-16 m believed good for 1034 ppCASTOR & TOTEM easily installed/removed for specialruns (eg heavy ion), interspersed with high lumi pp

LHC

SLHC

wide pipe (400mm) after HF and in its shadowSPC - 15/9/200849 J. Nash - CMS SLHC Issues

Infrastructure modifications: Yoke

Reinforced Shielding inside forward muons: up to ~2 automatically implies replacement of inner CSC, RPC

(alternatives with protection from new high HE/EE not considered)

Supplement YE4 wall with borated polythene

Improve shielding of HF PMT’s

possibility of increased YE1-YE2 separation toinsert another detector layer?


CMS Upgrade Management


Conclusions CMS is progressing on defining the scope of

phase 1 and phase 2 upgrades A substantial program of R&D is well

underway The coming years will see development of

detailed project plans for the upgrades Need to work with the LHCC to understand the

transition from phase 1 to phase 2


cms upgrade issues

Documents

nash cms slhc issues

nash cms slhc issues

slhc physics

cms upgrade issuesspc

phase iidamn

phase irequirements

phase iitracking triggermuons

phase iphase iiwhat