Toward Assessing HF with Beam Halo Muons & Beam-Gas Events …tuning HF when beam returns excerpts from US-CMS presentation 9/26/08 Michael Schmitt, NWU work of Cathode Strip Chamber muon group

Cathode Strip Chambers: CSC’s HF-

Minus Muon Endcap

Muon group analyzed three runs compared with beam halo MC 62084: Wed. afternoon, beam 2 50 passes 62096: Wed. eve, beam 2 hundreds of passes 62232: Thur. near midnight, beam 2 captured. Muon trigger “hit” CSC chamber = rechits in at least four layers out of six

LHC Beam Notation CMS +x +z +y LHC “Beam 1”: Enters p5 from p4 Traverses CMS from ME+ to ME  LHC “Beam 2”: Enters p5 from p6 Traverses CMS from ME  to ME+

Machine –Beam 2 injected IP8 Threaded to dump in IP6 Steered then inject and dump –Beam 1 injected IP2 Threaded through to collimators in IP5 CMS Tues, 9-Sept –20 shots of Beam 1 onto collimator 150m upstream of CMS –Large CSC events require CSC (reduced HV for subsequent dumps) Sept. 5 th to 7 th & 9 th +x +z +y Traverses CMS from ME+ to ME 

First Events: Collimators Closed ~2 x10 9 protons on collimator ~150 m upstream of CMS HO,HF - dark blue; HB,HE - light blue; ECAL- pink; Muon - green; Tracker & Magnet Off ~200 muons per cm 2

Sept. 10 th : 27 km/hr (Aymar) September 10 Machine: –Beam 1 injected IP2 Threaded around the machine in 1h Trajectory steering gave 2 or 3 turns –Beam 2 injected IP8 Threaded around the machine in 1h30 Trajectory steering gave 2 or 3 turns Q and Q’ trims gave a few hundred turns CMS –Big splash events observed when beam onto collimators (as before) TeV observed in ECAL-HCAL HCAL DQM gave information instantly –Halo muons observed once beam started passing through CMS with the CSCs and Calos Prompt analysis from CSC fully reconstructed muons on real time

First beam: many events with a large number of hit chambers beam 1

fan-like, several tracks on incident side, a little on the other. beam 1

particles do not shower in muon iron yokes: muons beam 2 (early) very clean chambers…little noise

many very clean events reconstruct muons through entire CMS detector

events with 2 or 3 muons:

muons reconstruct across 20m w/o beam alignment

What do muon triggers look like in HCal? muon track does pass through the tower with the high energy measurement.

Beam-Halo: HE+Muon CSC Run Event Run Event 4632 S. Won Time distribution of HE-matched hits may be useful for rejection of halo hits in the future

Beam - Gas events hit HF+ HF+HF- Beam Direction  

Summary: muon and beam gas data look good thousands of clean, well-reconstructed beam halo events are available linked with Schmitt to assess HF (with Lawson and Carleton)

BACKUP

Track Based Alignment J. Pivarski (Texas A&M) Use simultaneous solution of fits to residuals from overlapping regions to align chambers to each other

Chamber Illumination: Beam-2 Halo Run 62096: ME  4ME  3ME  2ME  1 ME+1ME+2ME+3ME+4