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Yttrium Doped Lead Tungstate Crystals



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Yttrium Doped Lead Tungstate Crystals Ren yuan Zhu California Institute of Technology 0DUFK CMS Week CERN Outline Segregation coefficient of the yttrium in PbWO4 crystal Performance of the yttrium doped PbWO4 crystals The transmittance and the birefringence 0DUFK CMS Week Ren yuan Zhu Yttrium Segregation Coefficient The Glow Discharge Mass Spectroscopy GDMS was used to determine yttrium concentration in crystals A fit to the GDMS data extracts the yttrium segregation coefficient ke in PbWO4 Ke 0 91 0 04 0DUFK CMS Week Ren yuan Zhu Properties of Yttrium Doped PWO Crystals UV excited photo luminescence and excited radio luminescence Decay kinetics Radiation damage Light response uniformity Radiation Induced Color centers Published in NIM A480 2002 468 0DUFK CMS Week Ren yuan Zhu Set up for Luminescence Measurement Photo Luminescence Surface excited by UV No Internal absorption 0DUFK Radio Luminescence Whole body excited by ray With internal absorption CMS Week Ren yuan Zhu Photo and Radio Luminescence 15 20 nm red shift of the peak of the radio luminescence to that of the photo luminescence The shift is explained by internal absorption 0DUFK CMS Week Ren yuan Zhu Luminescence before and after Irradiations Both excitation and emission spectra are not affected by the ray irradiation 0DUFK CMS Week Ren yuan Zhu Decay Kinetics 85 and 95 of light in 50 and 100 ns 0DUFK CMS Week Ren yuan Zhu Radiation Damage 5 15 and 15 30 light output loss under 15 and 500 rad h 0DUFK CMS Week Ren yuan Zhu Summary of Light Output Measurements Sample LO 1 MeV Fraction LO at R rad h ID p e J 50ns 1Ps 100ns 1Ps 15 100 500 1000 SIC S301 9 4 63 5 92 0 96 6 96 6 87 3 79 5 74 3 SIC S347 9 9 66 9 91 3 97 8 95 1 88 6 82 1 78 0 SIC S392 8 4 56 8 92 0 97 3 98 2 91 3 83 6 80 2 SIC S412 8 3 56 1 94 6 98 6 98 2 91 2 85 9 85 3 SIC S643 8 9 60 1 88 8 98 9 88 3 79 8 SIC S762 10 6 71 6 85 6 94 2 91 5 84 2 81 4 SIC 606 10 4 70 3 88 3 98 4 91 7 79 3 SIC 678 10 4 70 3 85 2 93 5 94 2 76 0 59 6 SIC 679 10 8 73 0 85 0 94 7 93 5 73 5 57 3 BGRI 824 11 4 77 0 83 5 95 5 89 0 78 7 69 9 BGRI 826 11 2 75 7 84 4 96 7 86 0 74 7 62 2 BTCP 2133 8 2 55 4 89 9 97 8 89 2 78 6 72 3 70 5 BTCP 2162 9 3 62 8 89 8 97 9 86 1 76 8 70 3 68 2 BTCP 5615 7 2 48 6 86 6 98 5 82 9 BTCP 5618 7 2 48 6 86 8 98 5 77 4 BTCP 5658 8 8 59 5 83 9 97 7 76 1 63 6 0DUFK CMS Week Ren yuan Zhu Light Response Uniformity The response y along the axis was fit to a linear function 0DUFK y ymid CMS Week Ren yuan Zhu 1 x xmid 1 Color Center Density Radiation induced color center density or absorption coefficient D 1 LALequilibrium 1 LALbefore LAL light attenuation length 0DUFK CMS Week Ren yuan Zhu Color Center Decomposition C1 3 07 eV 400 nm 0 76 eV 0DUFK C2 2 30 eV 540 nm 0 19 eV CMS Week Ren yuan Zhu Longitudinal Transmittance C axis limit A axis limit Transmittance approaches theoretical limit low intrinsic absorption 0DUFK CMS Week Ren yuan Zhu Transmittance and Birefringence Czochralski grown along the a axis 0DUFK Bridgman grown along the c axis CMS Week Ren yuan Zhu PWO Crystals Grown along c Axis PWO crystals grown along the c axis are isotropic transversely 0DUFK CMS Week Ren yuan Zhu PWO Crystals Grown along c Axis cont Good longitudinal uniformity in the transverse transmittance 0DUFK CMS Week Ren yuan Zhu PWO Crystals Grown along a Axis Some longitudinal non uniformity in the transverse transmittance 0DUFK CMS Week Ren yuan Zhu Summary The concentration of yttrium ions in PbWO4 crystals is rather uniform the segregation coefficient is 0 91 0 04 The scintillation light of yttrium doped PbWO4 crystals has a broad distribution with a peak at 420 nm the luminescence spectra and longitudinal light response uniformity are not affected by the J ray irradiations Yttrium doping is effective in reducing slow scintillation component the ratio between light outputs integrated in 100 and 1000 ns is about 95 The yttrium doped PbWO4 crystals have adequate radiation hardness for the barrel ECAL but may fall short for the end caps 0DUFK CMS Week CERN Summary Cont The radiation induced absorption in all yttrium doped samples can be decomposed to two common color centers peaked at 400 nm 3 07 eV and 540 nm 2 30 eV with widths of 0 76 eV and 0 19 eV respectively Because of the birefringence PWO crystals grown along the c axis is isotropic transversely while crystals grown along the a axis are optically not isotropic transversely Also because of the birefringence PWO crystals grown along the c axis have lower theoretical limit in longitudinal transmittance which is significant in the short wavelength region 0DUFK CMS Week CERN


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