The Electromagnetic Calorimeter – 2005 Operation

J. Sowinski for the Collaboration

and the Builders

Indiana Univ. Michigan State Univ. ANL MITBNL Penn. State Univ.JINR Rice Univ.Kent State Univ. Texas A&M Univ. Valparaiso Univ. Funded by NSF

STARSTAR

Px P x a LL g part

LL

LL^

pQCD

MeasureKnow from DIS

“G”

G via partonic scattering from a gluon

• Dominant reaction mechanism

• Experimentally clean reaction mechanism

• Large a

Prefer

LL^

STARSTAR

Hard scattering pQCD, factorization

Heavy flavor rare

-jet coinc. rare

Jets and 0s

The STAR Detector at RHIC

At the heart of STAR is the world’s largest Time Projection Chamber

STARSTAR

STAR Detector• Large solid angle• Not hermetic• Tracking in 5kG field• EM Calorimetry• “Slow” DAQ (100Hz)• Sophisiticated triggers

Detector

=0

Forward Pion Detector

Endcap EM Calorimeter

Beam-Beam Counters

Time Projection Chamber

-2<η< 2

Barrel EM Calorimeter

-1<η< 1

1<η< 2-4.1<η< -3.3

2<|η|< 5

Solenoidal MagneticField 5kG

=2= -1

Tracking

Lum. Monitor Local Polarim.

200320042005

Triggering

Triggering

= - ln(tan(/2)

STARSTAR

Barrel EMC

Endcap EMC

Star poletipStar magnetTPC

EM Calorimeters in STARSTAR

Endcap ElectroMagnetic Calorimeter• Pb Scint sampling calorimeter• 21 radiation lengths• 720 projective towers• Depth Segmentation

– 2 preshower layers, e/h 0/ disc.– High position resol. SMD 0/disc.– Postshower layer e/h discc.

• L0 trigger- high tower, jet patches

Simulated EM Shower

Shower Maximum Detector EEMC

• Resolves closely spaced showers for – ID

• ~7000 individually read out scintillating strips

• U and V plane in each 30osector• Essentially no coverage gaps

SMD profiles for a 9 GeV 0 candidate

U V8 cm 7 cm

Tower Energy signal PMT Box

MAPMT Boxes

PMTs and electronics on back of poletip

16 ch MAPMT and miniturized electronicsFor SMDs and Pre/Post Shower

Detector Readout and Trigger•Light carried out of magnet on fiber optics•Photomultiplier tubes for all signals•Digitized every beam crossing (110 ns)•Stored in pipeline for transfer on trigger•Tower energy can generate level 0

trigger–Highest tower –Total energy –Jet patch (1/6th in ) summed energy–Coincidences between jet patches

and other detectors

Highest tower ADC by patch

Highest Tower triggerThr =2.4 GeV prescale 6Thr =2.9 GeV no prescale

Jet Patch triggerSummed E in1/6th ofThr = 3.8 GeV

STARSTAR

MIP coincidence between all subsystems

Coincidence between 2 SMD planesHit pattern 0000000xx0000000 each plane

Calibration and status from Minimum Ionizing ParticlesInternally defined as MIP behavior in all 4 subsystems10% calib. of Tower Energy – 20% of other elementsAll but a handful of channels out of 9360 working

Tower Gains from MIPs

0s in the EEMCCluster finding algorithm•Consider SMD strips in hit

towers•Cluster around highest strip

above 8 MeV threshold•Include 5 strips either side•Cluster around next highest strip

above threshold + estimated tail of found clusters

•Find all clusters•Pair up between U and V

considering geometry of sector•Requires 2 clusters in each

SMD

pT~3-6 GeV Construct few % 0s in HT triggers (thr>2.9 Gev) At low pT trigger favors asymmetric decayCluster finding favors symmetric decay

2005 data enough stats to continue developing higher pT

algorithms

Initial attempts to understand spectrum shape

Jets found with Endcap HT trigger

Jets

jet

Endcap Calo

Away side jets in TPC + Calo’s

Need to develop better tracking in forward region= jet – HT

STARSTAR

Summary

•One year with full coverage•Two years of operation with full system•First large pp data set (6/05) being processed•>99% of elements working•Continued work on

– 0 finding– Tracking in forward region - Jets– direct finding– e/h discrimination

Clustering Algorithm Typical cases for 15 GeV 0

’”

Detector

=0

Forward Pion Detector

Endcap EM Calorimeter

Beam-Beam Counters

Time Projection Chamber

-2<η< 2

Barrel EM Calorimeter

-1<η< 1

1<η< 2-4.1<η< -3.3

2<|η|< 5

Solenoidal MagneticField 5kG

=2= -1

Tracking

Lum. Monitor Local Polarim.

200320042005

Triggering

Triggering

= - ln(tan(/2)

STARSTAR