1. Third Workshop on GEMs for CMS
Timeline so far :
Starting End 2009: Focused R & D with a CMS application in mind
Mid 2010: Upgrade R&D Proposal to Upgrade Steering Committee
September 2010: Workshop 1: 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.
March 2011: GEM Collaboration (GEMs for CMS) set up: ~ 120 collaborators, 20 insts.
June 2011: Workshop 2: showed continued consolidation of the technology and
defined a first application of GEMs in CMS
October 2011: Upgrade Technical Proposal:
MPGD solution for muon triggering & enhanced tracking in the
2.1>h>1.6 region (pages 42 (muon upgrade intro) and 141 (trigger))

2. Third Workshop on GEMs for CMS
11 Feb 2012: ‘Technical Proposal’, for installing two high h GEM stations each end in LS2,
submitted to Upgrade Project Managers (104 pages, 176 signatories, 35 inst.).
06 Mar 2012: Preliminary Review:
- GEM technology and resulting trigger performance thoroughly covered,
potential recognised.
- justification for GEMs cf possible cheaper LS2 technologies not confronted
(ex trigger turn-on curves wrt RPC)
- 7.5 M CHF cost prohibitive to approval given current state of phase 1 funding.
- invitation to Muon project management to consider plans for high h
-suggestion to propose a reduced scale system as a demonstrator.
18 Apr 2012: Workshop 3: WELCOME!! .
What now?

3. Third Workshop on GEMs for CMS
Agenda, after the intro talks, deals with:
operational experience with GEMs
integration and services
simulation, reconstruction, physics studies
on- and off- detector electronics, controls
trigger studies
detector performance
quality control
The techno-political issue the “GEMs for CMS” collaboration must also still address is how
to move forward from a highly successful R & D to a well defined, well justified,
broadly supported, approvable, affordable project in CMS.
The answer is GEMs …but what exactly is the question?

4. Third Workshop on GEMs for CMS
My suggestion is to move quickly forward with the demonstrator idea to give a target for
a real integrated system (not a test-beam prototype) to be installed in LS2.
Support of the CMS muon community and Upgrade Project managers is essential.
Self-sufficient, secure funding position, including all ancillary costs, is essential.
For a demonstrator, the compelling physics case can to some extent be postponed, pending
further simulations or even the results from the demonstrator.
But, the upgrade principle of “First do no harm” must be respected.
(includes not blocking a cheaper but comprehensive and effective LS2 upgrade alternative
at high h and not tying up CMS resources, including central resources, needed for
approved upgrades.)
How about a proposal to instrument a fraction of 1/1, 1/2 layers at one or both ends?
( make sure the services and the thermal issues are completely addressed and resourced).

5. (commented) Comments from Workshop 2
Last word…
(commented) Comments from Workshop 2
“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 2-3 x nominal pile-up
still true : could easily occur between LS2 and LS3.
Identify channels which particularly benefit from extended h range for tracking/triggering
of m such as: boosted objects with m decay channels
asymmetry, coupling & spin measurements
fusion processes
Studies like this will naturally contribute to making a case for maintaining/extending a
coherent detector system in the forward region. CMS needs to establish a set of
physics objectives first, before considering which new detector systems should be built, if any.
(see mandate of new forward region working group).
….these studies may help justify the use of space & resources for the GEM demonstrator
The GEM technology is likely to be a strong candidate for “forward” tracking, if any.