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STATUS on PWO crystals from Bogoroditsk after one year of preproduction for CMS-ECAL

Comprehensive review of one-year progress in CMS-ECAL crystal preproduction from BTCP batches, characterization, and radiation testing, highlighting improvements and results. Efforts focus on crystal quality and uniformity.

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STATUS on PWO crystals from Bogoroditsk after one year of preproduction for CMS-ECAL

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  1. STATUS on PWO crystals from Bogoroditsk after one year of preproduction for CMS-ECAL Etiennette Auffray SCINT 99, 16 August 1999

  2. Importance of R&D effort 95 98

  3. Since the 4th September 98, we received : • 1000 preproduction crystals from BTCP: • 100 : 04/09/98 • 100 : 03/11/98 • 200 : 08/12/98 • 200 : 22/03/99 • 400 : 22/06/99 • All have been visually Inspected • All have been characterised with ACCOS • (Automatic machine to measure : • 3D, transmission, decay time,LY) • Some have been irradiated • 61 irradiated in High dose rate (500Gy, 240Gy/h) • 129 irradiated in Low dose rate (3Gy, 0.15Gy/h) • 400 used for the 1st module of CMS/ECAL • in CERN/lab27 regional center First crystals La doped & progressively changed to Y-Nb doped

  4. Reception of first 100 preproduction crystals

  5. Quality check of first 1000 preproduction crystals

  6. Optical Specifications for Preproduction • Longitudinal transmission  10% at 350nm  55 % at 420nm  65 % at 600nm • Transversal transmission • For T=50%  6nm • S >1.5 %/nm between 340 and 370nm • For “blue” crystals : LY in labo27 at 8Xo  8 pe/MeV 2 pe/MeV with 1 EG&G APD (BT97) • Decay time LY(100ns)/LY(1s) > 90% No visible afterglow • < 0.5% background with 1MBq source in standart decay time measurement Good radiation Hardness

  7. Bogoroditsk Preproduction Status • 1500 crystals delivered Mid of August 16 August, 99 1998 1999 2000

  8. Dimensions AR-Nominal value On all dimensions Batch 1 19/100 rejected 19% Batch 2 14/100 rejected 14% Batch 2 19/200 rejected 8.5% -100m 0m

  9. Dimensions AR-Nominal value On all dimensions Batch 4 8/200 rejected 4% Batch 5 9/400 rejected 2.25 % -100m 0m

  10. 420nm Optical Transmission Distribution for 1000 crystals 3.2% below 55%

  11. 420nm Optical Transmission Batch 1 11/100 rejected 11% Batch 2 6/100 rejected 6% Batch 3 15/200 rejected 7.5%

  12. 420nm Optical Transmission Batch 4 0/200 rejected 0% Batch 5 0/400 rejected 0%

  13. Light Yield LY at 8Xo Distribution for 1000 crystals 2.2% below 8pe/MeV

  14. Light Yield Batch 1 0/100 rejected 0% Batch 2 0/100 rejected 0% Batch 3 1/200 rejected 0.5%

  15. Decay time % of emitted light in 100ns Distribution for 1000 crystals

  16. The slope of longitudinal transmission between 340nm & 370nm

  17. The slope of longitudinal transmission between 340nm & 370nm 0.1% below 1.5%

  18. Radiation damage certification of Russian crystals • Irradiation of ingot’s top and bottom parts • All crystals • At Bogoroditsk • To control radiation hardness uniformity • High dose & dose rate side irradiation (induced absorption at all l) • Sampling (20%) • At Bogoroditsk after March 99 • To control absolute radiation hardness and uniformity • Transverse transmission along the crystal • All crystals • At Bogoroditsk and at CERN • To control doping uniformity • Longitudinal transmission band edge slope • All crystals • At Bogoroditsk and at CERN • To predict radiation hardness • High dose & dose rate side irradiation (induced absorption at all l) • Sampling (20%) • At Geneva hospital (CERN) • To control absolute radiation hardness & uniformity • Low dose rate front irradiation (LY loss) • Sampling (20%) • At CERN (TIS) • To control radiation hardness in LHC conditions • Low dose rate side irradiation (transmission loss at ≠ l) • Sampling (20%) • At CERN (X5) • To control radiation hardness uniformity

  19. Sampling irradiation tests Batch 3 & 4 Front irradiation 0.15Gy/h

  20. Radiation Hardness Lateral irrad., 500Gy, 240Gy/h Front irrad., 1.5Gy, 0.15Gy/h

  21. 1000 crystals delivered 28 May 1999 Status of crystal deliveryfrom Bogoroditsk (Russia) 1998 1999 2000

  22. Conclusion The results on first 1000 preproduction crystals are very encouraging • Ramping up in production rate according to plans • Continous improvement • of the crystal characteristics from batch to batch : • Improvement of dimensions • Improvement of the transparency • (no more core defect) • Exceptional rejection for bad radiation hardness

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