1. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 1 Scintillating Crystals for Particle Physics Outline  Performance considerations  Table of crystal properties  Properties of Lead tungstate  Lead tungstate in CMS  Other future experiments  Summary

2. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 2 Performance Considerations  Light yield  Speed (scintillation decay time)  Radiation length / Molière radius  Resistance to radiation-induced darkening  Emission spectrum  Cost (including implications for associated detectors) The relative weight given to these considerations depends on the application. The choice of crystal usually involves a compromise

3. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 3 Crystal Properties

4. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 4 Lead Tungstate Properties Advantages: Fast Dense Radiation hard Emission in visible Disadvantages: Temperature dependence High refractive index Low light yield  Photodetector with gain

5. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 5 Compact Muon Solenoid Total mass : 12,500t Overall Diameter: 15.0m Overall Length: 21.6m Magnetic field: 4T ECAL Superconducting coil HCAL

6. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 6 CMS ECAL Layout 6.3 m 2.6 m Full projective geometry (‘Off-pointing’ by 3 o ) Barrel: 17x2 Crystal types End cap: 1 Crystal type

7. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 7 PWO Production at BTCP - Russia

8. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 8 ALICE (A Large Ion Collider Expt for LHC) PHOS

9. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 9 PHOS (Photon Spectrometer) Crystals from North Crystals-Apatity 17 280 Crystals (180 x 22 x 22 mm 3 ) 1.5 m 3, ~12.5 t PbWO 4 with PIN Diode readout

10. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 10 BTeV at Fermilab Due to start in 2008

11. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 11 BTeV Electromagnetic Calorimeter PbWO 4 with pmt readout 10 000 Crystals (220 x 28 x 28 mm 3 ) 1.7 m 3, ~14.3 t Prototype crystals: - Shanghai Institute of Ceramics - Bogoroditsk (BTCP)

12. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 12 MECO (Muon-electron conversion) BNL Electromagnetic Calorimeter Crystal option: 2300 crystals: 120 x 30 x 30 mm 3 BGO, PbWO 4,(GSO) under consideration APD Readout Planned operation: 2006 Search for  -  e -  (to 1 in 10 17 )

13. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 13 ANKE (Apparatus for studies of Nucleon and Kaon Ejectiles) Photon detector proposed for ANKE at COSY (Jülich) Due to operate in 2004

14. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 14 Photon detector for ANKE 0 0.5 m 800 Crystals (120 x 20 x 20 mm 3 ) x 35 x 35 0.075 m 3, ~630 kg PbWO 4 with fine-mesh pmt readout

15. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 15 Primex at Jefferson Lab PbWO 4 /Lead glass 1200 PbWO 4 Crystals 180 x 20 x 20 mm 3 Ordered from Shanghai Institute of Ceramics HyCal (Hybrid Calorimeter)

16. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 16 Comparison: PbWO 4, CeF 3, BaF 2 Application to Medium Energy Physics (E(   1 GeV) (Novotny et al. NIM A486(2002) 131) BaF 2 considered as the bench mark Conclude:PbWO 4 performs well, despite limited light yield CeF 3 attractive, requires further development of large homogeneous crystals Note:Studies elsewhere show light yield of PbWO 4 (and energy resolution) improved by doping with Tb or Mo - at expense of speed

17. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 17 Super B Factory BaBar: 6580 CsI(Tl) Xtals Belle: 8736 CsI(Tl) Xtals Scheme for Super B Factory Detector Super B Factory Candidate crystals: Pure CsI with APS LSO or GSO with APD ( )

18. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 18 Summary  Several future high energy experiments require very large volumes of crystal scintillator  The material of choice is PbWO 4 (Density, speed, radiation resistance, cost)  Despite low light yield, PbWO 4 is also proposed for medium energy applications  Improvements in light yield through doping could extend the range of applications of PbWO 4  Super B Factory might require a Fast, High light-yield, Radiation-resistant scintillator (CsI, GSO, LSO)

19. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 19 CMS Group at RAL - Interests  Electromagnetic Calorimeter design & construction  Photodetector development  Scintillator performance studies: Light yield, decay time using HEP Test Beam at ISIS Radiation Hardness (in collaboration with Brunel)  Dense scintillating glass R&D (In collaboration with Sheffield, Dept of Engineering Materials)

20. PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 20 Photodetectors: CMS ECAL end caps B-field orientation favourable for VPTs (Axes: 8.5 o < |  | < 25.5 o wrt to field) More radiation hard than Si diodes (with UV glass window) Gain 8 -10 at B = 4 T Active area of ~ 280 mm 2 /crystal Q.E. ~ 20% at 420 nm  = 26.5 mm MESH ANODE Vacuum Phototriode (VPT): Single stage photomultiplier tube with fine metal grid anode