New particle ID detector for Crystal

Ball at MAMI-CDaniel Watts, Daria Sokhan, Claire Tarbert

University of Edinburgh

John Annand, Douglas Macgregor, Evie Downie, J McGeorgeUniversity of Glasgow

• 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

• rPID-II >rPID-I

• Keep same segmentation (24)

• tscint = 4mm (PID-I: 2mm)

PID-II schematic

CB Tunnel PID-II scintillators

MWPCsupports

MWPCChambers

PMTs

M

WP

C =

133

mm

500mm

PMT support ring

beam

• PID-II – removable! (redesigned MWPC connectors)

PID-II schematic

P

ID(I

NN

ER

) =

108

.4m

m

Hamamatsu H3164 - 10

Active detectorregion

PID-II test module – light attenuation• 90Sr beta source

• Observe position of landau as source moved along scintillator → light attenuation

PID-II Test modulePID-I Test module

Enhancement near PMT

Distance from PMT (mm)

Po

siti

on

of

lan

dau

pea

k (

arb

un

its)

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 distributionup to 0.7 GeV

Isotropic angular distribution

No shower shaperestrictions

Pions K+

Protons

Energy deposited in CB (GeV)

En

erg

y d

ep

os

ite

d i

n P

ID-I

I (G

eV

)

1 2 3 4 5 6Delivery 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

Present status

Delivery of PMTs

• Manufacture/delivery of PID-II components complete

• Module testing completed in ~2 weeks

• Completed detector ready in early June

Summary

Liquid hydrogentarget

Radius mwpc = 66.5cm

PID-II

• PID-I support ring

router-rinner = 14mm

• 4 mm clearance each side

to the polarised target.

Hydrogen target will have

problem – clearance = 0mm!

65.5

51,5

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 H3164 - 10

Very preliminary decay gammas from nucleon knockout

12C(,ppp)9Li

Q value

Low energyclusters from shaded region

2.69 MeV

E=400-500 MeV

Simulated + signals in Crystal Ball

No restriction on shower size ≤ 2 crystals in + shower

+ decay

Nuclear interaction

Incident + energy (GeV)

Hig

hest

clu

ster

ene

rgy

(GeV

)

Very preliminary decay gammas from nucleon knockout

12C(,ppp)

Q value

Low energyclusters from shaded region

2.69 MeV

• rPID-II >rPID-I

• Same segmentation (24)

• Lscint chosen to give PID

Info for all proposed targets

• Lscint =50 cm (PID-I 32cm)

PID-II – schedule and status

PID-II Test modulePID-I Test module

New polarised target design