status of the cms detector

Paolo Rumerio, University of MarylandOn Behalf of the CMS Collaboration

The LHC and Dark Matter Ann Arbor, Michigan, January 6th -9th, 2009

Status of the CMS Detector

Overview

Paolo Rumerio, MarylandLHCDM, Ann Arbor, Jan 6th - 9th, 2009

Installation and Commissioning Beam Days Cosmic Run at Four Tesla Winter Shutdown Activities

The CMS Detector


ECAL

Si Tracker

3.8T solenoid

Muon chambers

HCAL

Iron yoke

Pixel

YB0

YE-1

Some detector component acronyms:Pixel: Barrel (BPix) and Endcap disks (FPix)Tracker: Inner Barrel (TIB), Inner Disks (TID), Outer Barrel (TOB), Endcaps (TEC)Electromagnetic Calorimeter: ECAL Barrel (EB) and ECAL Endcaps (EE)Hadronic Calorimeter: HCAL Barrel (HB), HCAL Endcap (HE), HCAL Forward (HF), HCAL Outer (HO)Muon Chambers: Drift Tubes (DT) in the barrel (also Muon Barrel - MB), Cathode Strip Chambers (CSC) in the endcaps (also Muon Endcaps - ME), Resistive Plate Chambers (RPC) in barrel end endcapsMagnetic field return yoke: Yoke Barrel (YB) and Yoke Endcaps (YE)

Lowering Barrel Wheels and Endcap Disks


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Barrel wheels: Jan. - Oct. 2007

Endcap disks: Jan. 07 – Jan. 08

Installing Detectors Inside the Magnet


…………….. ……….. …………….

Inserting HCAL barrel: Mar. 07

Installing ECAL Barrel: ended July 07

Inserting Silicon Strip Tracker: Dec 08. Cabling completed Mar. 08

YB0 After Cabling Dec. 07

Latest Installed Components


EE and Pixels were installed just before beam and worked quite well very soon

Beam pipe: insertion and

bakeout June 08

Pixels: inserted Aug. 08

ECAL endcaps: completed and fully installed

Aug. 08

CMS Closed – 3 September 2008


…………….. ……….. …………….

Commissioning


Magnet Test and Cosmic Challenge (MTCC) took place in summer 2006 on the surface of the experiment location Commissioning of the magnet and measuring of the field map Test of a vertical slice of the detector and cosmic data taking

Since May 2007, three- to ten-day-long exercises took place underground with the installed detector components, electronics and services Increasing size and number of participants, and scope of the exercises Balancing with

installation scheduleand detector local commissioning

Detector Participation versus Time

Cosmic Runs Without Magnetic Field


Sept.10: Beam

CRUZET3:Strip tracker joins

CRUZET4 : Pixel tracker and EE join (final CMS configuration)

CRUZET2

CRUZET1

Events CollectedVersus Time

End March 08

Since March 2008, global runs saw an increasing focus on stability of operations cosmic ray data

taking (hence named CRUZET - Cosmic RUns at ZEro Tesla)

First Beam


Sun and Mon, Sept. 7 and 8 Beam 1 (clockwise) single

“shots” onto a collimator 150 meters upstream of CMS (also called “splash” events)

Tue, Sept. 9 20 additional shots as above

Wed, Sept. 10 Circulating beams, beam 1

in the morning, beam 2 in the afternoon

Thu, Sept. 11 RF capture of beam

Beam Pickup and CMS Beam Condition Monitors

Fri, Sept. 19th A faulty electrical connection between a dipole and a quadrupole failed,

massive helium loss, and cryogenics and vacuum lost Beam elements in the region are being extracted and replaced or repaired

During all of these activities, CMS triggered and recorded data (without CMS magnetic field and with inner tracking systems kept off)

Event Display of a Beam-on-Collimator Event


…………….. ……….. …………….

11

From 2x10^9 protons

on a collimator 150

m upstrea

m

HCAL Energy ECAL Energy

Drift Tube hits


ECAL vs. HCAL Energy Correlation in Beam-on-Collimator Events

Correlation between reconstructed energy in the CMS Hadron Barrel calorimeter (HB) and Electron Barrel Calorimeter (EB) for beam-on-collimator events in September 2008. The large reconstructed energy values are the result of the hundreds of thousands

of muons which passed through the detector during each event.

Muon Chamber Number of Hitsin Beam-on-Collimator Events


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Linearity of the number of hits in the third ring of DT chambers vs. total ECAL energy for beam-on-collimator events

Synchronization of HCAL from Beam-on-Collimator Events


The pulse arrival time of beam-on-collimator events is predicted using geometry considerations

Left panel: difference between predicted and mean pulse arrival time beam-on-collimator events of Sep. 10. HCAL barrel uses tuned integration delays, while HCAL endcap,

forward and outer use not tuned delays Right panel: as above, with the following differences

beam-on-collimator events of Sep. 18 HCAL uses delays tuned from previous beam-on-collimator

runs (except a small region of the Outer calorimeter, omitted here)

RF Capture of the LHC Beam seen in HCAL Endcap Energy and CMS Trigger Time


Distribution of energy observed in the CMS Endcap Hadron Calorimeter. Before the capture of the LHC beam by the RF system, there is a high rate of energy deposit near the beam line. After the capture, the beam is quite clean.

Distribution of the CMS trigger time versus bunch crossing (BX) number. Before the capture of the LHC beam by the RF system, the trigger timing is spread over a few BXs. After the capture, the trigger timing is sharply peaked at BX=831.

Evidence of Beam Gas Collisions


Average energy as a function of eta in the CMS Forward Hadron Calorimeter (HF) for circulating beam events at LHC. The events are triggered by

the HF from LHC's Beam 2, which passes through the CMS Detector from negative to positive z.

The events are further selected to contain at least one deposit of 20 GeV in a tower which is registered by both the long and short fiber sections of the tower.

The long and short sections measure the total energy and the hadronic energy of a shower, respectively.

The peak in energy deposition towards positive pseudorapidity is a signature of beam-gas interactions near or within the detector, as the remnants of beam-gas interactions will have a small transverse momentum and a larger longitudinal momentum from the initiating proton.

Beam Halo vs. Cosmic Muons


Distribution of the angles of reconstructed muon tracks with respect to the plane perpendicular to the beam.

Beam halo muons typically make a small angle (blue histogram). Muons from cosmic rays pass through the cathode strip chambers at a more oblique angle, as seen when the beam is off (black histogram). When the beam is on (orange-shaded histogram) the distribution consists of two pieces, one of which closely resembles cosmic rays, and the other which matches the beam halo simulation. The normalization of the blue and black histograms are not based on any calculation; they are meant to guide the eye.

Beam Halo Muon in CSC and HCAL Beam Halo

Muons

Cosmic Muons

Beam Halo Hit Distribution


ME4ME3ME2ME1

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

Hit distribution in the Cathod Strip Chambers Red arrows indicate the order beam traversed endcap disks A few chambers are being fixed during the winter shutdown

Cosmic Run At Four Tesla - CRAFT


CRAFT


Four weeks of continuous running 19 days with magnet at the operational setting of B=3.8 T Gained operational experience and put in evidence sources of inefficiency

Collected 370 M cosmic events, out of which 290 M with B = 3.8 T. Of those with magnetic field on: 87% have a muon track

reconstructed in the chambers 3% have a muon track with strip

tracker hits (~7.5 M tracks) 3 x 10-4 have a track with pixel hits

(~75K tracks)

Data operation performed satisfactorily 600 TB of data volume transferred Prompt reconstruction at Tier 0

completed with a typical latency of 6h Tier 0 to Tier 1 at average of 240

MB/s

Number of cosmic events vs. time

Tracker Performance


On track Strip clusters S/N ratio, corrected for the track angle

TOB thick sensors: S/N = 32TIB/TID thin sensors: S/N = 27/25TEC (mixed thickness): S/N = 30 Track hit finding efficiency

TIB and TOB layers

Muon momentum distribution high quality tracks (8 hits, one in TIB layers 1-2, one in TOB layers 5-6) Partial CRAFT statistics (expected >70K tracks at PT>100 GeV for full CRAFT)

S/N

Ent

ries

Layer

Tracker Alignment


Chi Square distribution Using 4M tracks for alignment and 1M for

validation “Unaligned” is the nominal geometry “CRUZET” is the geometry obtained from the

B=0T runs using the Hits and Impact Point method and survey constraints

“CRAFTHIP” is the geometry obtained from the Hits and Impact Point algorithm applied to CRAFT data, including survey constraints

“CRAFTMP” is the geometry obtained from the Millepede algorithm applied to CRAFT data

Mean of residual distributions (cm)

Only modules with >30 hits considered TIB 96%, TID 98%, TOB 98%, TEC 94% HIP algorithm : TIB RMS = 26m TOB RMS = 28m

Pixel Occupancy and Alignment


Barrel aligned at module level (200-300 hits, 89%)

Endcap aligned at half-disk level (8)

RMS=47m

RMS=112m

Drift Tube Muon System


Residual Distributions Reasonable agreement

between data and MC after cosmic muonarrival time fit

Sigma ~ 200 – 260 m Sector 4 of wheel -2 is

shown here B field degrades MB1

distribution in wheels +/-2

Data MC

MB4

MB3

MB2

MB1

Drift Tubes Drift Velocity Along z-Axis with/without Field


Innermost stations on outer wheels have largest radial field Maximum difference in drift velocity is 3%

HCAL Barrel Muon Response


HB energy: signal from HB towerscorrected for muon path length in HB

Event selection: Muon track matching in DT and Tracker 20 GeV/c < Pµ < 1000 GeV/c CRAFT: 200 K events MC: 15 K events

Test Beam 2006Pµ = 150 GeV/c

Mean signal = 2.8 GeV

CRAFT data

ECAL Barrel Occupancy


Higher occupancy in top and bottom regions (vertical flux of cosmic rays) Top EB- is closer to the shaft of the CMS P5 pit Other modulations are due to the cluster efficiency varying with crystal light yield. EB+7 and EB+16 suffered from low voltage problems - being fixed. Empty 5x5 crystal regions are trigger towers masked from the readout.

Occupancy map of clusters in cosmic muon runs during CRAFT Avalanche photodiode gain set to x4 the LHC conditions. Clusters are seeded either from a single crystal or a pair of adjacent crystals above threshold

EB+7

EB+16

ECAL Stopping Power


Stopping power for cosmic muons as a function of their momentum Muon momentum is measured in the tracker The ECAL energy deposit is measured by the cluster energy matched to the track The track length in ECAL is estimated from track propagation inside ECAL crystals Loose selection on the track distance of closest approach to the centre of CMS

Blue dots: CRAFT experimental dataBlack line: dE/ρdx in PbWO4

Red dashed line: collision lossBlue dashed line: bremsstrahlung radiation

Activities for and after winter shutdown


Detector opening started on Nov 17th Started a selected list of interventions/repairs for problematic channels

(order of the percent) CMS cooling system maintenance (done) Installation of Preshower detector in February

Continue the optimization of detector operations Optimization of online system and procedures to eliminate possible

sources of data taking inefficiency Centralization and optimization of detector control system and monitoring Consolidation of data quality monitor and certification Aim to reduce the needed number of shifters and expertise to decrease

long term manpower load Schedule for Resuming Commissioning Activities

Global run sessions to be resumed mid-Feb First CRUZET (Cosmic RUn at ZEro Tesla) in April Detector closed around mid-May 2009 Extended CRAFT (Cosmic Run At Four Tesla) before LHC beam

Conclusions


A long, intensive and challenging installation and commissioning campaign was carried out successfully All major components of the detector have been installed and commissioned Preshower detector will be installed in February

CMS was ready for beam Collected and exploited at best the beam data delivered before the September 19th

incident A one-month-long cosmic ray run with nominal magnetic field has been taken Commissioned and verified stability of operations (detector, magnet and operators) Pointed out inefficiencies and issues to be addressed Some interventions on detector components are currently being carried out none of the problems being worked on would have prevented efficient data taking if

collisions had been delivered Schedule for this year has been defined It will evolve with time, depending on ongoing repair activities and progresses made Commissioning activities will resume by the end of this month. The goal is to optimize

performance, increase efficiency and reduce manpower and expertise needed in control room

CMS will be closed again with enough contingency for being ready for beam, allowing another extended cosmic ray run with magnetic field

status of the cms detector

Documents

paolo rumerio

barrel bpix

hcal barrel hb

ecal barrel eb

yoke barrel yb

dark matter ann arbor

outer barrel tob

inner barrel tib