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 GMn
Use 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.
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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 ∆t = 1.5ns
o Expect to reach ∆t = 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)
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COMPASS HCalo Performance
Energy resolution
In range of 2-10 GeV/c
∆E/E = 20-30%
Position resolution
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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 Θnq to separate (quasi-)elastic events
• GEp : Need for track reconstruction, reduce pseudo-tracks
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BigCal for GEp experiment
Used in Hall C Gep3 experiment
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BigCal performance in Hall C GEp3
Comparison 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 GEp3
xcal is measured BigCal horizontal coordinate
xHMS is predicted position from beam energy & proton momentum
∆xHMS = 0.9 cm
∆x2cal = ∆x2diff − ∆x2HMS
∆xcal = 0.55 cm
xdiff = xcal -xHMS
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BigCal for GEp
Reassemble 20 x 76 block array.
1520 blocks
Block size is 4x4x40 and 3.8x3.8x45 cm3
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Covers area of 0.80 x 3.04 = 2.4 m2
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BigCal electronics
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
76
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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”
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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”
Turquoise box is next “group of 32” in
vertical which overlaps by 2 rows.
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”
Turquoise box is next “group of 32” in
vertical which overlaps by 2 rows.
Dark green is next group
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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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5
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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.
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Trigger discussed in O. Hansen’s talk.
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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 resolution
•
o Needed in all FF experiments to separate (quasi-)elastic from inelastic
o 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
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F.
GEANT study of HCalo Performance
•Response of neutrons and protons nearly identical
Neutrons
Protons
2.5 GeV/c
3.2 GeV/c
4.0 GeV/c
5.4 GeV/c
6.2 GeV/c
7.3 GeV/c
8.1 GeV/c
9.4 GeV/c
10.5 GeV/c
F. Benmokhtar
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GEANT study of HCalo Performance
F. Benmokhtar
•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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F.
GEANT study of HCalo Performance
F. Benmokhtar
•Response of neutrons and protons nearly identical
•Good position resolution
•GMn, GEn, GEp: Cut on Θnq to separate quasi-elastic events
•GEp : Need for track reconstruction, reduce pseudo-tracks
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COMPASS HCalo Performance
Extensive tests of calorimeter performance were done at CERN
for pions, electrons and muons at 2-100 GeV
Muons
Calibrated energy
spectra for
10 GeV beam
Pions
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COMPASS Hcalo
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GEp experiment
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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
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