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Scintillating Crystals for Particle Physics

Scintillating Crystals for Particle Physics. Outline Performance considerations Table of crystal properties Properties of Lead tungstate Lead tungstate in CMS Other future experiments Summary. Performance Considerations. Light yield Speed (scintillation decay time)

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Scintillating Crystals for Particle Physics

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

  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 PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 2

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

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

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

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

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

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

  9. PHOS (Photon Spectrometer) PbWO4 with PIN Diode readout 17 280 Crystals (180 x 22 x 22 mm3) 1.5 m3, ~12.5 t Crystals from North Crystals-Apatity PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 9

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

  11. BTeV Electromagnetic Calorimeter PbWO4 with pmt readout 10 000 Crystals (220 x 28 x 28 mm3) 1.7 m3, ~14.3 t Prototype crystals: - Shanghai Institute of Ceramics - Bogoroditsk (BTCP) PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 11

  12. MECO (Muon-electron conversion) BNL Search for m- N  e-N (to 1 in 1017) Crystal option: 2300 crystals: 120 x 30 x 30 mm3 BGO, PbWO4,(GSO) under consideration APD Readout Electromagnetic Calorimeter Planned operation: 2006 PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 12

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

  14. Photon detector for ANKE PbWO4 with fine-mesh pmt readout 800 Crystals (120 x 20 x 20 mm3) x 35 x 35 0.075 m3, ~630 kg 0 0.5 m PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 14

  15. Primex at Jefferson Lab PbWO4/Lead glass 1200 PbWO4 Crystals 180 x 20 x 20 mm3 Ordered from Shanghai Institute of Ceramics HyCal (Hybrid Calorimeter) PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 15

  16. Comparison: PbWO4, CeF3 , BaF2 Application to Medium Energy Physics (E(g) 1 GeV) (Novotny et al. NIM A486(2002) 131) BaF2 considered as the bench mark Conclude: PbWO4 performs well, despite limited light yield CeF3 attractive, requires further development of large homogeneous crystals Note: Studies elsewhere show light yield of PbWO4 (and energy resolution) improved by doping with Tb or Mo - at expense of speed PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 16

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

  18. Summary • Several future high energy experiments require very large volumes of crystal scintillator • The material of choice is PbWO4 (Density, speed, radiation resistance, cost) • Despite low light yield, PbWO4 is also proposed for medium energy applications • Improvements in light yield through doping could extend the range of applications of PbWO4 • Super B Factory might require a Fast, High light-yield, Radiation-resistant scintillator (CsI, GSO, LSO) PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 18

  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) PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 19

  20. =26.5 mm MESH ANODE Photodetectors: CMS ECAL end caps • B-field orientation favourable for VPTs • (Axes: 8.5o < || < 25.5o wrt to field) • More radiation hard than Si diodes • (with UV glass window) • Gain 8 -10 at B = 4 T • Active area of ~ 280 mm2/crystal • Q.E. ~ 20% at 420 nm • Vacuum Phototriode (VPT): • Single stage photomultiplier tube with fine metal gridanode PPARC forum on developments in scintillator technology 17.9.02 R M Brown - RAL 20

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