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

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

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.

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

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

EC Physics Requirement Electron- hadron separation 20:1 - 100:1 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)

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

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

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

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

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

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

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.

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 - 100:1 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

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.

Thank You Comments and suggestions will be appreciated