1. for SoLID Collaboration
EM Calorimeters for SoLID at Jefferson Lab - requirement, preliminary design
Zhiwen Zhao (UVa)
Jin Huang (LANL), Mehdi Meziane (Duke),
Xiaochao Zheng (UVa), Paul Reimer (ANL),
Nuclear Physics Group (William&Mary)
for SoLID Collaboration
Calor2012
2012/06/05

2. Jefferson Lab Hall A A C B Newport News, Virginia, USA
SRF powered linear accelerator provides continuous polarized electron beam
Ebeam = 6 GeV -> 12GeV upgrade
Pbeam = 85%
Building new Hall D - Gluex
Upgrading 3 existing Hall A, B, C A C B

3. SoLID (Solenoidal Large Intensity Device)
One of major new equipments in Hall A 12GeV era.
It is a general purpose device with approved experiments for 1 year beam time already. More experiments are proposed.
Electromagnetic calorimeter (EC) provides key electron/pion separation. Its modules will be shared between different configurations.

4. Parity Violation DIS (PVDIS)
Approved beam time: 169 days, at 1039cm-2s-1 luminosity
Standard Model
Precision test of Standard Model by measuring parity violation DIS electron asymmetry (A ~ 0.5ppm)
4 months at 11 GeV
2 months at 6.6 GeV
Error bar σA/A(%) shown at center of bins in Q2, x
a precision measurement of the electroweak mixing angle at the same Q2 as the NuTeV experiment
a determination of the u/d ratio in the proton
a measurement of charge symmetry violation at high x that could be relevant to addressing the NuTeV anomaly
a investigation of the presence of nucleon higher twist effects in polarized electron scattering

5. Semi-Inclusive DIS (SIDIS)
Approved beam time: 125 days, at 1036cm-2s-1 luminosity
TMD
Nucleon Spin
QCD Dynamics
Quark OAM / Spin
QCD Factorization
3-D Tomography
Lattice QCD
Models
Precision mapping of transverse momentum dependent parton distributions (TMD)
TMD links:
Nucleon spin
Parton spin
Parton intrinsic motion

6. EC Physics Requirement
Electron- hadron separation
20: :1 pion rejection in electron sample over 1-7GeV/c
Energy resolution: σ(E)/E ~ 5%/√E
Radiation resistance, 5x105 rad
Time response
σ <~ a few hundreds ps
provide trigger/identify beam bunch (TOF PID)
Magnetic field 1.5 T for SIDIS large angle calorimeter. Silicon based photon-sensors can’t survive high neutron environment. PMTs need to be away from high magnetic field.
Provide shower Position
σ ~ 1 cm, for tracking initial seed / suppress background
Modules can be easily swapped and rearranged for different configuration.
The SIDIS layout need to satisfy 2-fold rotation symmetry
Coverage (m2): 4 (SIDIS LC) + 10 (SIDIS FC); 15 (PVDIS)

7. EC Type: Shashlyk Shashlyk calorimeter Satisfy the SoLID requirement
IHEP, COMPASS Shashlik, 2010
Shashlyk calorimeter
Lead-scintillator sampling calorimeter
WLS Fiber collects and reads out light
Satisfy the SoLID requirement
Good energy resolution (tunable)
transverse size can be customized
Radiation hardness ~ 500 krad
Easier to collect and read out the light
Well developed technology, used by many experiments
IHEP production rate about 200 per month 7

8. Design 1: Pb/scintillator ratio
Minimize scintillator ratio while reaching the pion rejection
Reach 100:1 pion rejection w/ Pb =0.6mm/Layer, 1.5 mm Scint.
Electron Efficiency
1/(Pion rejection)
Preliminary
97%
Preliminary
1/100 Rejection
p (GeV)
p (GeV)
SIDIS large angle:
3~7 GeV

9. Design 2: Preshower/Shower
Preshower and shower have separate WLS readout.
Preliminary
Preshower
Shower
WLS
Reach Best rejection at 3-5rad length
Reach Best rejection at ~20 rad length
Can not contain EM shower
More hadron shower
Total Rad Length
Preshower Rad Length

10. Design 3: Lateral Size Preliminary Good Balance w/ 50ns ADC gate
block Size (cm)

11. Design 4: Layout Preferred Square - Easy assembly - Mature production
- Easier rearrangement
06/06/2012

12. Design 5: Radiation Simulation
Low E photon dominant
Total
Electron
Photon
Pi+
Pi-
Preliminary
Can be shielded 2mm-Pb equivalent

13. Design 6: Fibers and Connectors
Wave Length Shifting fibers (WLS):
KURARAY Y11
Clear Fibers:
KURARAY clear PS, Super Eska…,
Connectors
One to one WLS/clear fiber connector, used in previous experiments (LHCb, Minos,…) light loss studies and design well documented.
Lucite rod to couple the fibers option would reduce the cost, no information about the light loss yet.
Searching for fiber bundle to bundle connection.

14. Basic Features of Preliminary Design
Based on COMPASS Shashlyk module design.
0.6mm lead/1.5mm scintillator, 200 layers, 42cm in length (20 X0)
Balance between longitudinal size and pion rejection
20: :1 pion rejection depending on momentum
10x10cm of transverse size in square shape
Balance between cost and resolution/background
~1000 modules for forward angle EC, ~500 modules for large angle EC
Splitting : ~4 X0 for preshower and ~16 X0 for shower
Maximizing e-pi separation
~100 WLS fibers/module (KURARAY Y11)
1/cm2 fiber density to sample the EM shower
Searching for fiber bundle to bundle connection

15. Summary
Jlab 12GeV Upgrade and SoLID spectrometer will open doors to exciting physics, including precision test of standard model and study of nucleon structure and strong interaction.
EC is the key detector for electron-hadron separation in SoLID.
The challenge is to
reach good pion rejection
operate in high radiation environment
and strong magnetic field.
Preliminary design is on-going.

16. Thank You Comments and suggestions will be appreciated