H C A L

11th International Conference on Advanced

Technology and Particle Physics Villa Olmo (Como - Italy), October 5 - 9, 2009

THE PERFORMANCE OF THE CMS HADRON CALORIMETER with

COSMIC MUONS

Vasken HagopianFlorida State University/ Note Dame University

For the CMS Hadron Calorimeter Collaboration

15 October 2009 11th International Conference, COMO, Italy

H C A L

CERN in Geneva, Switzerland

CMS

Test Beam

25 October 2009 11th International Conference, COMO, Italy

H C A L

HCAL DetectorPerformance

• In 2008 about 300 million cosmic muons were recorded with the 3.8 tesla magnet on called CRAFT (Cosmic Run At Four Tesla) and another 3 million cosmic muons at Zero field (CRUZET).

• OUTLINE• Calibration using ’s𝛍 • Time alignment• Electronic noise

35 October 2009 11th International Conference, COMO, Italy

H C A L

The CMS Detector

HF

HOHB

HE

45 October 2009 11th International Conference, COMO, Italy

H C A L

End Cap & HO

55 October 2009 11th International Conference, COMO, Italy

H C A L

STATUS OF HCAL

• HCAL has various sub-systems: Barrel HB. End Cap HE. Outer calorimeter HO. Forward HF, Very forward CASTOR AND ZDC.

• This presentation covers only HB, HE and HO.

• HCAL IS NOW COMPLETELY ASSEMBLED IN CMS.

• Portions of each subsystem was tested and calibrated in the CERH H2 test beam.

65 October 2009 11th International Conference, COMO, Italy

H C A L

HADRON CALORIMETER

FEE are locations of Front End Electronics.Right end of beam line is the intersection point.

ECAL modules are inside HCAL and the combined informationof ECAL and HCAL determines the hadron energy.

IP

75 October 2009 11th International Conference, COMO, Italy

H C A L

COSMIC MUONS

• 300 million cosmic muons were taken with the CMS magnet on in 2008 and a similar number with the magnet off.

• In Sept 2008, for a few days LHC circulated 450 GeV/c beam. We observed beam gas events and later the beam was stopped by collimators 150 m from CMS. These “splash” events were used for timing.

85 October 2009 11th International Conference, COMO, Italy

H C A L

Calorimeter Calibration

• Procedure for calibration:

• Calibration using both ECAL and HCAL.

• Step 1 is in the test beam (2006 for HB, HO, HF and 2007 for HE). Using electrons, pions and muons.

• Radioactive wire sourcing of each tile (HB and HE) before lowering CMS into cavern.

• Cosmic muons for final calibration before LHC beam.

95 October 2009 11th International Conference, COMO, Italy

H C A L

Cosmic muon energy

Cosmic ’s.𝛍 p = 7 to 300 GeV/c. Not energy corrected

105 October 2009 11th International Conference, COMO, Italy

H C A L

Cosmic muon energy

Left: Cosmic momentum distribution𝛍Right: Energy loss (dE/dx) vs. p and comparison to expected value

115 October 2009 11th International Conference, COMO, Italy

H C A L

Calibration constants refined using 2008 data. Barrel only.2009 data: Pµ = 5-100 GeV/c. Signal corrected for path length and momentum to 25 GeV/c.

Mean response for HB+/HB- is in good agreement

125 October 2009 11th International Conference, COMO, Italy

H C A L

First LHC Beam in 2008

“Splash” Event

Wed, 10 Sept. 2008“Splash” events observed when beam (450 GeV, 4109 p) struck collimators 150m upstream of CMS Halo muons observed on (uncaptured and captured) started passing through CMS

Data-taking with LHC beam.

Data-taking with LHC beam.

135 October 2009 11th International Conference, COMO, Italy

H C A L

LHC Beam: Beam GasEnergy Deposit in HE

HCAL Endcap: un-captured and RF-captured circulating beam

145 October 2009 11th International Conference, COMO, Italy

H C A L

HCAL Electronic NoiseData Box (RBX) and HPD

RBX Noise: noise hits in multiple HPDs in a RBX 40GeV < E < 420GeV HPD Noise: noise hits in only one HPD in a RBX ion feedback (nhits < 10 ) below 40 GeV discharge (nhits>=10) above 420 GeV

155 October 2009 11th International Conference, COMO, Italy

H C A L

Fake Missing Transverse Energy in CRAFT Data

5 October 2009 11th International Conference, COMO, Italy

16

Algorithms are off line software that reduce the contribution dueto noise.

H C A L

Timing alignment

• Laser distribution aligns to a few nsec.

• Front end electronics can delay time in 1 nsec steps.

• Time (start) of event depends on event energy.

• Final alignment adjustment using “splash” events.

• Time alignment now is about 1 nsec.

175 October 2009 11th International Conference, COMO, Italy

H C A L

Timing Corrections using “Splash” Events

5 October 2009 11th International Conference, COMO, Italy

18

H C A L

Time Filtering

5 October 2009 11th International Conference, COMO, Italy

19

H C A L

SiPM

5 October 2009 11th International Conference, COMO, Italy

20

H C A L

HO Upgrade

215 October 2009

•HO measures energy leakage from barrel calorimeter.•No direct calibration. Equalization using 𝛍’s.•Most HPD noise is in HO as axes are not aligned well with magnetic field direction.•Investigating SiPM as replacement of HPD’s.

H C A L

Other tests

• HCAL is very stable in time and energy during operation.

• Zero suppression is effective in reducing data to less than 20% occupancy for nominal luminosity.

• Splash events confirmed calibration constant that give uniform energy.

5 October 2009 11th International Conference, COMO, Italy

22

H C A L

Physics of CMS

• Standard model breaks down at E ~ 1 TeV

• New physics is expected at TeV scale.

• Dark matter search is critical; Calorimeter

required to measure missing energy.

• Discoveries should revolutionize particle

physics and cosmology & provide window to

physics at unification scale.235 October 2009 11th International Conference,

COMO, Italy

H C A L

Conclusion

• HCAL assembly and installation completed. Now initial calibration complete. Final calibration with collisions.

• CMS will soon start taking data

• Already working on upgrade for increased luminosity. Scintillators will be damaged and other components will have reduced effectiveness.

245 October 2009 11th International Conference, COMO, Italy