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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 - PowerPoint PPT Presentation
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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. 5th to 7th & 9th
+x
+z+y
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