cathode strip chambers status report

22 Sept. 2008 G. Rakness (UCLA) 1

Cathode Strip Chambers

Status Report

Greg RaknessUniversity of California,

Los Angeles

CMS week plenary sessionCERN

22 Sept. 2008


Sources of Muons Used for CSC Commissioning (I)

• Cosmic rays– Expansion of the system from few 468

chambers• Asynchronous muons over the full angular

spectrum


Intra-CSC Trigger Synchronization Cosmic Rays

ChamberId = SectorId*100+StationId*10+CSCID

Synchronize chambers on one endcap w.r.t. a reference chamber on that endcap

Synchronization of (most) chambers to better than 0.2bx

ME+

ME

D. Wang (UF)

Use chamber overlaps with cosmic rays to synchronize the chambers to each other on average


Run 57795 (CRUZET-4):

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

ME3 ME4ME2ME1

Recall: Chamber Illumination with Cosmic Rays

Plots by A. Kubik and M. Schmitt (Northwestern)


Sources of Muons Used for CSC Commissioning (II)

• Single beam bunch in LHC (~2x109 protons)– Beam passes through CMS beam

dump• Synchronous muons approximately parallel

to beam

– Beam captured several turns• Synchronous muons approximately parallel

to beam


CSC “Halo Muon” Trigger Single Beams

x

ME+ ME

TOF 2 bx

(Beam-1) halo muon

Normal proton

collisions

LHC mode: both endcaps trigger simultaneously on IP muons

“Halo Muon” trigger: CSC Track Finder selects tracks with small

• Trigger on outgoing endcap (i.e., ME for Beam-1)

Approximate timing of muons from IP

• [Note: for first beams, the incoming endcap was also included in the trigger (delayed by 2bx). This is no longer true…]


Chamber Illumination: Beam-2 Halo

http://lotus.phys.northwestern.edu/~kubik/newdata/run62096/

Run 62096:

ME4ME3ME2ME1

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


Beam Halo Event through Both Endcaps

More event displays are stored athttp://www.nuhep.northwestern.edu/~schmittm/CMS/TEMP/event_displays/

Run 62384Event 56199


Zoom in..

Most beam halo events look like this…


3-Muon Event in the CSC’s

http://www.nuhep.northwestern.edu/~schmittm/CMS/RESULTS/results.html


Sources of Muons Used for CSC Commissioning

• Single beam bunch in LHC (~2x109 protons)– Dumps into collimators ~150m away

from CMS• Synchronous “splashes” of muons + stuff


Coincident with collimator dumps:“Monster” CSC events

• Some numbers:– Event size 3MB (normal size ~few kB)– 160k/200k strips with data

• Causes (irrecoverable) error somewhere in CSC DCC Global DAQ Myrinet chain – Forced to stop and restart run…

• Local DAQ took event with no errors – Local readout through different path…

• To avoid this DAQ problem: remove CSC from Global DAQ during beam dumps into upstream collimator

Under investigation…


Collimator dump “Monster” CSC event

Reconstructed segments from Local DAQ data…


Data Analysis

Halo muons: angles of muons and beam structure


Reasonable description of beam ON data: combination of • beam halo • cosmic rays

(Separate normalization of blue and black curves not quantitative…)

Cosmic rays

Beam halo

Single beam: reconstructed track angle w.r.t. the transverse plane

http://www.nuhep.northwestern.edu/~schmittm/CMS/RESULTS/results.html


Cosmic rays do not care about beam structure…

~ Cosmic rays~ Beam halo

A. Kubik (Northwestern)

Separate Beam Halo and Cosmic Rays by Track Angle

look at the BX distribution

Beam halo muons come in single bx number, as expected…


Beam-2: Distribution of BX valueshttps://cmsdaq.cern.ch/elog/shift/3528

For BEAM-1 (19 Sept):

“… CSC remains [the] reference…” I.Mikulec (Trigger elog 680)

For BEAM-2 (10 Sept):

CSC Halo measured to be in time with HF technical trigger…

Delayed BPTX2 to be in time with HFTT and CSC Halo…

https://cmsdaq.cern.ch/elog/shift/3528


Data Analysis (II)

Chamber performance with Beam Halo Muons


Number of hits on a reconstructed segment.In MC we assume 100% efficiency for fiducial hits.



Efficiency to obtain a recHit in each given layer, for all chambers in ME+2/2

S. Stoynev (Northwestern)


Towards Alignment Constants…


Endcap z-positions with magnet at 0T, 3T

First reconstructions:• ME+2,3,4 stations at

B=0T, 3T• Simultaneous Rφ fit for

all SLMs in ME+2, ME+3 at B=0T, 3T

Compression comparable to MTCC at equivalent

magnetic field

XSLM [mm]

ZC

MS [

mm

]

• Integration of Barrel-Endcap-Link systems underway• Initial integrated model of link+endcap available

• Provide an integrated, global muon geometry• Upload geometry in ORCON/ORCOFF to be used in reconstruction • Combine/Compare with track-based alignment

G. Gomez (Cantabria)


Track Based AlignmentJ. Pivarski (Texas A&M)

Use simultaneous solution of fits to residuals from overlapping regions to align chambers to each other (For details, see alignment meeting Wednesday)


Summary Q: Is CSC ready for beam?

A: Yes (but we still have a lot to do!)

Online DQM “EMU status00” plot: Green = system able to provide at least two muon stubs


Backup slides


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+


CSC Inter-Endcap Synchronization with HE

ME+ and ME endcaps synchronized with each other

Avg = 6.3 Avg = 5.2

Avg = 5.1Avg = 5.2

Accurate TTC CCB fiber lengths implemented (Jay Hauser

[UCLA])

Before:CRUZET-3

After: CRUZET-4


Separate beam halo and cosmic rays by track angle (previous slide)

look at the BX distribution

The beam halo comes mostly at a single bx, while the cosmic rays

are everywhere, as expected.

(zoom-in)

~ Cosmic rays

~ Beam halo


cathode strip chambers status report

Documents

beam structuresingle

beam halo events

chelogshift3528for beam

beam haloa

cms beam dumpsynchronous

angles of muons

turnssynchronous muons

chambersasynchronous