Exploring Muon Phase 2 Options: A, B, and C for Enhanced Detector Capabilities

1. Muon Phase 2 Options A, B, and C Jay Hauser, UCLA • Updated from 11-Mar-2013 talk at Gmu meeting https://indico.cern.ch/conferenceDisplay.py?confId=236794 • CMS Week presentations and recent discussions: • Better understand linkage with endcap calorimetry upgrade • Future meetings: • General Muon (GMu) meeting next Monday (Apr. 29) • May 8: Forward Detector Working Group meeting that will focus on muons

2. Muon Phase 2 Options, IMHO • Minimal: if endcap calorimeter geometry is fixed • Calorimeter degradation allowed at cost to physics capabilities • Limited options for muon detector (maybe electronics, GE2/1, RE1/2) Additionally, if new endcap calorimeter & tracking coverage to |h|<4.0: • Extend muon coverage to 2.4<|h|<3.5 in “conventional” way • Add muon detectors at the back of the present HE and/or behind YE4 • Used for muon tagging, not L1 trigger: increase acceptance, could reduce MET • Alternate to plan B: add iron muon toroids in place of HF to cover 2.4<|h|<4.0 • Not terribly expensive, option to provide trigger • General reluctance: need to provide good physics motivation (including different kind of muon reconstruction)

3. Muon Option A: Minimal changes if endcap calorimeter geometry fixed • Replace electronics as necessary, for increases in L1 trigger latency and event accept rate • CSC new front end for latency > 6 ms, DT electronics if rate>300 kHz • Cost ~14+5 MChF, respectively • “Redundancy” argument for additional detectors in |h| < 2.4 seems insufficient • Best case was GE1/1, committee felt that was not justification enough • Depends mostly on inefficiency or bad performance of CSC, a weak argument • L1 trigger could still make some additions to improve rate or efficiency • GE2/1 and RE1/2 are two projects that have been discussed, not yet proposed • Unlikely to put muon tagger behind YE4 to cover 2.4 < |h| < 3.0 • No space available unless HF moved backwards, even then high rates and needs simulation

4. Muon tagger for 2.4<|h|<3.0 ? • In this view it looks possible, but…

5. Detailed view of HF region • In the more detail drawing it looks impossible

6. Muon Option B:New EE/HE, extend muon coverage to |h|<3.5 • In scenario where Tracker and endcap calorimeter coverage increased to |h|<4.0 • Refurbishment of endcap very difficult in situ; rebuild the whole thing • Rad-hard calor technology seems to allow this • Extend muon coverage to 2.4 < |h| < 3.5 or so • In space behind HE, or make HE a “tracking calorimeter“ where the tail of had shower = muon detector, or • In space behind YE4 • Rates are high, but use as “tagging” detector, don’t trigger • Have a high-momentum central track: is there a muon tag nearby?

7. Muon detectors in new endcap • At back of present HE • Totally new calorimeter • Existing structure too “hot” • Coverage options: • Minimal (top), maximal (bottom) shown on right • {1.5, 2.1, 2.4} < |h| < {3.5, 4.0} • Complement or replace ME1/1 • “Integrated” option • Build all of HE with GEM technology, for example m new HE m

8. Muon detectors behind YE3 • Similar to muon “tagger” already discussed but extend to |h|=3.5 or so • HF replaced by something that stops particles for |h|>4 • Little HF? Inside cone? • TAS+? • Shielding of muon tagger on all sides needed m tagger Jets, underlying events

9. Muon Option C:New EE/HE, add iron muon toroids in place of HF • Similar size, weight as HF, cover 2.4<|h|<4.0? • Gives B*L around 4 T*m, very good bending, but limited resolution due to multiple scattering • Innermost part, still need shielding of muon detectors • Could be used for triggering if justified by physics • Toroids themselves are not so expensive ~7 MChF, total cost maybe 10-30 MChF • But need to change name of our experiment? Detectors, iron core toroids New TAS, shielding New endcap

10. Branch points • In any case, will do electronics upgrades as necessary to accommodate L1 trigger changes • Endcap calorimeter replacement, or not? • This is unlikely to be decided by DESY Upgrades Week, early June • If NO, options are limited: • Probably just update the electronics as necessary • N.B. the GE2/1 and RE1/2 are on the table as enhancements to trigger • If YES, it gets more interesting, in addition can propose: • Detectors at the back of the present HE and maybe a back tagger, or • Muon toroid detectors

11. Possible discussion topics • Or, if not the time now, to discuss at another Gmu meeting • Redundancy as a weak argument • Additional trigger rate reduction arguments (e.g. GE2/1) • Creating space between YE3, HF for muon tagger • Details on new HE calorimeters: creating space for muon detectors, etc. • “ME0” within HE choice of detector technology • Toroids: magnetic forces on them & YE3 • Toroids choice of detector technology • Uses of high-h muons to increase acceptance, reduce sources of MET