slide1

SBS Hadron and Electron Calorimeters

Mark Jones

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SBS Hadron and Electron Calorimeters

Mark Jones

•Overview of GEn, GMn setup

•Overview of GEp setup

•The SBS hadron calorimeter (HCalo)•Design of HCalo•Neutron and proton detection efficiency, energy and position

resolution

•BigCal for GEp (not part of this technical review)

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Experiment Setup for GEn and GMnUse standard BigBite double layer calorimeter

• Electron PID (combined with gas Cherenkov). • Electron energies in range from 1.2 to 3.5 GeV. High threshold for trigger.

Hadron calorimeter based on successful design used in COMPASS. • Proton and Neutron momentum from 2.6 to 10.5 GeV/c

•Need good position (angular) resolution to separate (quasi-) elastic from inelastic background.

slide4

Experiment Setup for GEp Reconfigure BigCal for electron detection.

• Electron momentum range from 3.3 to 3.9 GeV/c• Use 20cm thick Al wall to reduce flux of low energy background.• High threshold to reduce single arm trigger rate.• Position resolution needed in track reconstruction ( L. Pentchev’s talk)

Use same Hadron calorimeter• Proton momentum range from 3.5 to 8.6 GeV/c• High threshold to reduce the single arm trigger rate• Position resolution needed in track reconstruction

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Module of Hadron Calorimeter•As starting point, use COMPASS design of JINR group.

Iron and scintillator sandwich

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Module of Hadron Calorimeter Carnegie Mellon and JINR will design and build calorimeter.

• Optimize length for the experiment’s energy range• Improve timing resolution.

o COMPASS Dt = 1.5ns o Expect to reach Dt = 0.4ns

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Hadron Calorimeter (Hcalo)

• Each block has frontal area 15x15 cm2

•Arrange 11x22 blocks

•Area = 5.5 m2

•Total weight is 36 tons (w/o frame)

slide8

COMPASS HCalo Performance

Position resolutionIn range of 2-10 GeV/cDE/E = 20-30%

Energy resolution

slide9

GEANT study of HCalo Performance

Response of neutrons and protons nearly identical Good energy resolution

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GEANT study of HCalo Performance

Response of neutrons and protons nearly identical Good energy resolution

• High thresholds reduce backgrounds• GMn: Near identical p/n efficiency reduces systematics

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GEANT study of HCalo Performance

Response of neutrons and protons nearly identical Good position resolution

• GMn, GEn, GEp: Cut on Qnq to separate (quasi-)elastic events• GEp : Need for track reconstruction, reduce pseudo-tracks

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BigCal for GEp experimentUsed in Hall C Gep3 experiment

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BigCal performance in Hall C GEp3Comparison of energy resolution from GEANT simulation to data for different electron energies and thicknesses of Al plate

Agreement between GEANT and data is excellent

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BigCal performance in Hall C GEp3xcal is measured BigCal horizontal coordinatexHMS is predicted position from beam energy & proton momentum

DxHMS = 0.9 cm

Dxcal = 0.55 cm

xdiff = xcal -xHMS

¢ x2cal = ¢ x2di®¡ ¢ x2HMS

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BigCal for GEp

Reassemble 20 x 76 block array. 1520 blocks

Block size is 4x4x40 and 3.8x3.8x45 cm3

Covers area of 0.80 x 3.04 = 2.4 m2

76

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BigCal electronics

76

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Make groups of 4x2 blocks Use NIM “summing” modules

(special built for and used in Hall C experiment) which have:

• 8 analog inputs• 8 analog outputs (amplify 5x)• 6 “sum of 8” analog outputs

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BigCal electronics

Each red block is 4x2 grouping into NIM “summing” module.

Need 5x38 = 190 modules (available)

38

5

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BigCal electronics

For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)

Blue box represents one “group of 32”

38

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BigCal electronics

For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)

Blue box represents one “group of 32” Turquoise box is next “group of 32” in

vertical which overlaps by 2 rows. 38

5

slide20

BigCal electronics

For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)

Blue box represents one “group of 32” Turquoise box is next “group of 32” in

vertical which overlaps by 2 rows. Dark green is next group

38

5

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BigCal electronics

For trigger form “group of 32” by summing analog output of 4 of “group of 8”. (Use available Lecroy NIM FI/FO)

Most “groups of 8” are in 4 “groups of 32”

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BigCal electronics

Each dot is the center of “group of 32”

Have 4x37 = 148 “group of 32” which will be used in trigger.

Trigger discussed in O. Hansen’s talk.37

4

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Conclusions Hadron Calorimeter

• Used in all three form factor experiments.• Based on the proven COMPASS design.

• Energy resolution allows high thresholds to eliminate background and lower trigger rates

• Position resolution allows for good angular resolutiono Needed in all FF experiments to separate (quasi-)elastic from inelastico Needed in GEp to help in tracking with large low-energy background rates

• Neutron and proton response above 2.5 GeV/c nearly identical Electron Calorimeter

• GEn and GMn use standard BigBite calorimeter• GEp uses a reconfigured BigCal calorimeter• High threshold reduces trigger rate• Position resolution needed for tracking and separating (quasi-) elastic from inelastic.

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Backup Slides

slide25

GEANT study of HCalo Performance

•Response of neutrons and protons nearly identical

F.

F. Benmokhtar

Protons

Neutrons 2.5 GeV/c3.2 GeV/c4.0 GeV/c5.4 GeV/c6.2 GeV/c7.3 GeV/c8.1 GeV/c9.4 GeV/c10.5 GeV/c

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GEANT study of HCalo Performance

•Response of neutrons and protons nearly identical•Good energy resolution

• High thresholds reduce backgrounds• GMn: Near identical p/n efficiency reduces systematics

F. Benmokhtar

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GEANT study of HCalo Performance

•Response of neutrons and protons nearly identical•Good position resolution

• GMn, GEn, GEp: Cut on Qnq to separate quasi-elastic events• GEp : Need for track reconstruction, reduce pseudo-tracks

F.

F. Benmokhtar

slide28

COMPASS HCalo Performance

Muons

Pions

Extensive tests of calorimeter performance were done at CERN for pions, electrons and muons at 2-100 GeV

Calibrated energy spectra for 10 GeV beam

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COMPASS Hcalo

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GEp experiment

slide31

GEp experiment: Radiation Damage

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GEp experiment: Radiation Damage

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GEn experiment

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GMn experiment

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GMn experiment

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Geant study of HCalo Performance

•Response of neutrons and protons nearly identical•Good position resolution

• GMn, GEn, GEp: Cut on Qnq to separate quasi-elastic events• GEp : Need for track reconstruction, reduce pseudo-tracks

•Good energy resolution• High thresholds reduce backgrounds• GMn: Near identical p/n efficiency reduces systematics