Workshop 24 Jun 11 AB

Workshop on GEMs for CMS high

Last September’s workshop showed that MPGD technology is now mature.

Stable operation of large area GEMs : at high rate with common non-flammable gas mixture.

Mass, industrialized production possible

Costs still high but falling.

This workshop is about defining the first application of GEMs in CMS

Objective: launch the preparation of an addendum to the Upgrade Technical Proposal describing a GEM solution for muon triggering and enhanced tracking in the 2.1>>1.6 region.

Workshop 24 Jun 11 AB

Comments II

“The Physics Case” should therefore be built in the challenging post-TDR scenario  where:

- 300 fb-1 already collected   - centre-of-mass energy: 14 TeV, lumi 2-3 x 1034 cm-2s-1

   - events are with nominal or 2 x nominal pile-up Identify channels which particularly benefit from enhanced range for tracking/triggering of such as: boosted objects with decay channels

asymmetry, coupling & spin measurements fusion processes

Studies like this will naturally contribute to making a case for a coherent detector system in the true “forward” region >3, where CMS needs to establish a set of physics objectives first, before considering which detector systems should be built, if any.

The GEM technology is likely to be a strong candidate for “forward” tracking, if any.

Workshop 24 Jun 11 AB

Physics studies

Framework is in place:

reconstruction and identification of muons with GEMs works and gives results as expected

GEMs with excellent point resolution offer the opportunity to obtain a redundanttracking capability in the region where the Muon system contributes significantlyto momentum resolution

Now need to do real physics studies, simulating the harshness of the real environment to quantify the impact of a highly redundant system with improvedtracking capability.

The benefits may actually be clearer once real benchmark processes are considered.

Workshop 24 Jun 11 AB

Trigger studies

• started thinking about importing MPGD information, into CSCTF “not technically impossible”

• redundancy: fortify – regions around cracks (η~1.5-1.6)

– regions with key position information (ME 1/1)

• pT assignment:– currently working on reaching best performance with

information we have in hand, LUT stage

– post-processing is where full precision is used,these studies are yet to come - stay tuned..

Workshop 24 Jun 11 AB

Trigger studies

Results presented for baseline and MPGD like geometries. Two chamber models used for simulation

PAC logic optimized for better use of MPGD. Best results, when both inner planes used for measurement

When MPGD detectors used – benefit visible from better granularity and no clusters

Doubling spatial resolution improves (3~4x rate drop) when two first stations used for measurement. Going further (increasing spatial resolution 8x) gives 8~9x rate reduction

But…..PAC chips have limited volume and cannot hold infinite number of patterns

Workshop 24 Jun 11 AB

Prototype results

Fully operational GEM detectors 990 x (445 – 220 mm) have been designed and produced after long intense work on small size prototypes.

Test-beams at RD51 and CMS setup with small size and full-size prototypes we demonstrated that the candidate prototype is addressing all the requested requirements in terms of high efficiency and gain, stable safe and reliable operation in magnetic field at CMS-LHC environment.

Workshop 24 Jun 11 AB

Electronics for GEMs

Workshop 24 Jun 11 AB

L1 track trigger

•Incorporate L1 trigger as is now done at HLT:–Attach tracker hits to improve PT assignment precision from 15% standalone muon measurement to 1.5% with the tracker

•Improves sign determination & provides vertex constraints–Find pixel tracks within cone around muon track and compute sum PT as an isolation criterion

•Less sensitive to pile-up than calorimetric information if primary vertex of hard-scattering can be determined (~100 vertices total at SLHC!)

•To do this requires information on muons finer than the current 0.052.5°–No problem, since both are already available at 0.0125 and 0.015°

Workshop 24 Jun 11 AB

Putting MPGDs in tracking trigger

• Worth examining the potential for including high resolution tracking devices in the tracking trigger

• May really pay off for luminosity 5×1034 ie Phase2 upgrade

• But what about creep of shielding edge to protect CSC’s?

Workshop 24 Jun 11 AB

Mechanical integration

Installation procedures: initial studies in detail, no showstoppers tooling and logistic scenarios to be looked at

Workshop 24 Jun 11 AB

Production

•GEM single mask process is stable•CMS project can be done at CERN (manufacture and testing) if needed•Thanks to new equipment the prices will drop•The new stretching method can reduce a lot the assembly time (and presumably the cost)•Building 107 will help again to reduce prices.

•Potential for transferring technology to eg Korea looks good

Workshop 24 Jun 11 AB

Costs of GEM-based upgrade

June 24, 2011

2nd Workshop on GEMs for CMS 12

Number to take home for now : 5 MCHF for 3 layers

NB This is ADDITIONAL to the 65MCHF total given in the upgrade TP!!!!

Workshop 24 Jun 11 AB

GEM Collaboration

Impressive commitment of people and resources and good demonstration ofcollective progress.

Important to understand how this collaboration relates to CMS , RD51 and to existing sub-detector projects in CMS.

Governance, finance, use of common resources

Moving from R &D towards a real construction project forces a change of mindsetand results in many detailed problems being (forced to be) solved.

How to spawn off a set of defined construction projects from a detector developmentproject?

Workshop 24 Jun 11 AB

Schedule for fwd mu GEMS

TP Dec 2011

Planning towards ready for installation in 2016.

Looks reasonable, but:

Interference from RPC4 project

Interference from RD51 requirement

Care when extracting spend profile

(LHC schedule shifts?)

Workshop 24 Jun 11 AB

Conclude

Much work done…even more still to do

Prospects for initial application of GEMs to endcap muon upgrade are good

TP could be produced in about 6 months

TDR at end of 2012

Prospects for further GEM applications are excellent once physics case is made.