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

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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. 5th to 7th & 9th

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Traverses CMS from ME+ to ME

First Events: Collimators Closed~2 x109 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 cm2

Sept. 10th : 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)

- 100-1000 TeV observed in ECAL-HCALHCAL 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 doespass through the tower with thehigh energy measurement.

Beam-Halo: HE+Muon CSCRun 62096Event 598642

Run 62096Event 4632

S. Won 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 AlignmentJ. Pivarski (Texas A&M)

Use simultaneous solution of fits to residuals from overlapping regions to align chambers to each other

Chamber Illumination: Beam-2 HaloRun 62096:

ME4ME3ME2ME1

ME+1 ME+2 ME+3 ME+4