New particle ID detector for Crystal Ball at MAMI-C Daniel Watts, University of Edinburgh John Annand 1, B. Briscoe 3, A. Clarkson 2, Evie Downie 1, D. Glazier 2, S. Lumsden 2, Daria Sokhan 2, C McGeorge 1,Claire Tarbert 2 1- University of Glasgow 2- University of Edinburgh 3- George Washington university

Constraints of MWPC-I and targets → siting of PMTs at downstream end Design specifications Good separation of p, with little overhead in material before MWPC and CB detectors PID-I

MWPC-II & PID-II MWPC-II redesigned for MAMI-C experiments PID-II outside MWPC  inbetween the MWPC chambers  → Opted for setup similar to PID-I But PMTs at upstream end - TAPS

r PID-II >r PID-I Keep same segmentation (24) t scint = 4mm (PID-I: 2mm) PID-II schematic CB Tunnel PID-II scintillators MWPC supports MWPC Chambers PMTs  MWPC = 133mm 500mm PMT support ring  beam PID-II – removable! (redesigned MWPC connectors) PID-II schematic  PID(INNER) = 108.4mm Hamamatsu H

Delivery of scint. Cutting & prep of scint. Lightguide manufacture Element assembly & tests Detector assembly & tests Total construction time ~ 5.2 months Implementation into MWPC & CB months PID-II – schedule and status Delivery of PMTs ~1.5 month delay - Replacement of scintillator strips. New batch of manufactured by ELJEN 7

PMTs Scintillator HV input and signal readout 3He target nose Al support ring

PID-II GEANT Simulation Use PID-I simulation parameters – light output, light collection efficiency, QE … → Reasonable agreement with experimental data Include increase in PID-II scintillator thickness Flat KE distribution up to 0.7 GeV Isotropic angular distribution No shower shape restrictions Pions K+K+ Protons Energy deposited in CB (GeV) Energy deposited in PID-II (GeV)

3 day old bananas - all PID2 elements Data from 3He target - NO  restriction or correction for path length in the scintillator CB Energy (MeV) PID2 Ebergy (a.u) Proton punch through

Detector ready for use Summary

Data from first test PID Trigger – CH2 target All 24 elements give good signals PID2 Protons Pions PID1

Liquid hydrogen target Radius mwpc = 66.5cm

Active detector region PID-II test module – light attenuation 90 Sr beta source Observe position of landau as source moved along scintillator → light attenuation PID-II Test module PID-I Test module Enhancement near PMT Distance from PMT (mm) Position of landau peak (arb units)

CB Tunnel PID-II Scintillators  inner = 116.4mm MWPC supports MWPC Chambers PMTs  MWPC = 133mm (outer diameter of PID support ring) 500mm scintillator length PMT support ring  beam  PID(INNER) = 108.4mm (inner diameter of PID ring) Hamamatsu H Plastic downstream scintillator support  inner = mm (For detail see additional figure) Chamber length (between the supports) = 570 mm Schematic of PID-II for use with the Crystal D. Watts 20/04/06 BEAM

PID-II PID-I support ring r outer -r inner = 14mm 4 mm clearance each side to the polarised target. Hydrogen target will have problem – clearance = 0mm! ,5

PID-II & polarised target

PID-II PMTs Same tubes and bases as for PID-I BUT use new packaged tube + base assemblies -include magnetic shield Hamamatsu H

Preliminary decay gammas from nucleon knockout 12 C( ,ppp) 9 Li Q value Low energy clusters from shaded region 2.69 MeV E  = MeV i=1 3 Also look at pp, 4p, 5p … knockout Missing Energy (MeV) = E  –  T pi –T rec Energy of cluster (MeV)

Simulated  + signals in Crystal Ball No restriction on shower size ≤ 2 crystals in  + shower  + decay Nuclear interaction Incident  + energy (GeV) Highest cluster energy (GeV)

Very preliminary decay gammas from nucleon knockout 12 C( ,ppp) Q value Low energy clusters from shaded region 2.69 MeV

r PID-II >r PID-I Same segmentation (24) L scint chosen to give PID Info for all proposed targets L scint =50 cm (PID-I 32cm) PID-II – schedule and status PID-II Test module PID-I Test module

New polarised target design