1. Apatity, Bogoroditsk and Shankhai PWO Crystals under Gamma Irradiation (PRELIMINARY RESULTS) Apatity IHEP Khurchatov North Crystals CMS + BTeV Alice Presented by Vasily Kachanov IHEP Protvino (IHEP), July 28, 2004

2. V. Kachanov IHEP, July 28, 2004 The goals of our study are: -to find proper PWO growing technology for Apatity plant -compare the radiation damages of the crystals produced by the Bogoroditsk in the end of 2000, Apatity in March - July 2004 and Shankhai in 2000 Cs-137 gamma source was used for the lateral irradiation with dose rates 25 rad/h and 100 rad/h in air. Light output and transparency measurements were provided continuously during the gamma irradiation process. LED-monitoring system stability better than 0.5% over one week. Hamamatsu PMT was used as photodetector, anode current integrated during 1500 nsec was used as signal. Leqroy electronics was used for data taking Introduction

3. V. Kachanov IHEP, July 28, 2004 The gamma radioactive source Cs-137 (E= 0.661 MeV) with activity of 5  10 12 Bq was used for crystal irradiation. Two sets of gamma irradiation: 1) 25 rad/h rad/h 2)100 rad/h for each The Commercial dosimeter DKS-AT1123 was used for the dose rate measurements (accuracy better than 20%). Gamma irradiation (Cs-137) Cs-137 a

4. V. Kachanov IHEP, July 28, 2004 Dose rate profiles in crystal Dose rate, a.u. Transversal dose rate profiles under gamma irradiation Cs-137 source X, mm

5. V. Kachanov IHEP, July 28, 2004 Signal loss, a.u. Crystal # CMS-2442 ~20 h ~28 hours ~20 h 25 rad/h100 rad/h 0.65 0.9 Current signal LED ( 470 nm) signal Recovery at 25rad/h 0.7 0.92

6. V. Kachanov IHEP, July 28, 2004 Signal loss, a.u. Crystal # CMS-2443 0.92 Current signal LED ( 470 nm) signal 25 rad/h 100 rad/h Recovery at 0 rad/h ~20 h 0.88 0.9 ? Temperature ? 0.978 0.985 ~46 h

7. V. Kachanov IHEP, July 28, 2004 Crystal # Bogo-5995 Signal loss, a.u. Current signal LED ( 470 nm) signal 100 rad/h Recovery at 0 rad/h ~70 hours ~24 h 100 rad/h; 1 hour irradiation 0.79 0.955 0.97 0.76

8. V. Kachanov IHEP, July 28, 2004 Crystal # Apatit-028 EE size, made in April-May 2004) Signal loss, a.u. Current signal LED ( 470 nm) signal 100 rad/h Recovery at 0 rad/h 0.5 0.74 100 rad/h; 1 hour irradiation 0.81 0.6 ~70 h ~45 h

9. V. Kachanov IHEP, July 28, 2004 Crystal # Apatit-052 EE size, made in April-May 2004 Signal loss, a.u. Current signal LED ( 470 nm) signal ~66 h 100 rad/h Recovery at 0 rad/h ~22 h 100 rad/h; 1 hour irradiation 0.81 0.85 0.6 0.68 ?

10. V. Kachanov IHEP, July 28, 2004 Crystal # Apatit-054 EE size, made in April-May 2004 Signal loss, a.u. Current signal LED ( 470 nm) signal 100 rad/h Recovery at 0 rad/h ~70 h ~42 h 100 rad/h; 1 hour irradiation 0.56 0.8 0.64 0.85

11. V. Kachanov IHEP, July 28, 2004 Crystal # Apatit-0068p EE size, made in July 2004 Signal loss, a.u. Current signal LED ( 470 nm) signal 100 rad/h 0.75 ~21 hours 0.93

12. V. Kachanov IHEP, July 28, 2004 Crystal # Apatit-0067p EE size,made in July 2004 Signal loss, a.u. Current signal LED ( 470 nm) signal ~22 hours 100 rad/h 0.85 0.94

13. V. Kachanov IHEP, July 28, 2004 Crystal # Apatit-0064p EE size,made in July 2004 Signal loss, a.u. Current signal LED ( 470 nm) signal ~22 hours 100 rad/h 0.75 0.92

14. V. Kachanov IHEP, July 28, 2004 Source-LED correlation Crystal # CMS-2442 Normalized LED (470 nm) signal Normalized source (current) signal 25 rad/h 100 rad/h Recovery at 25rad/h

15. V. Kachanov IHEP, July 28, 2004 Source-LED correlation Crystal # Apatit-028 Normalized LED (470 nm) signal Normalized source (current) signal 100 rad/h

16. V. Kachanov IHEP, July 28, 2004 Source-LED correlation Crystal # Apatit-0068p Normalized LED (470 nm) signal Normalized source (current) signal 100 rad/h

17. V. Kachanov IHEP, July 28, 2004 A summary for the signal loss for the Apatity and BTCP crystals (EE size) XtalDose rate (rad/h) Irradiation time (h) Signal current loss (%) Signal LED loss (%) Apat-028100705026 Apat-052100704018.5 Apat-0541007044.520.5 Bogo-599510070244.5 CMS-24422520225 CMS-2442100283511 CMS-2443252081.8 CMS-244310046122.1 Apat-006810021256.7 Apat-00671002115.56.0 Apat-006610021153.5 Apat-006410021257.8

18. V. Kachanov IHEP, July 28, 2004 XtalDose rate (rad/h) Irradiation time (h) Signal current loss (%) Signal LED loss (%) Apa1060810019.5143.5 Apa 976210024277.5 Apa1049110020124 Apa105871002223.56 Apa10603100173618 Apa1064810020379 Apa1067610021204.5 Apa1071710021235.7 Apa 141210020175.8 BTeV size (27x27x220 mm^3, rectangular) Shan-T09100442611 Shan-T19100773211.5 XtalDose rate (rad/h) Irradiation time (h) Signal current loss (%) Signal LED loss (%) Apat-028100705026 Apat-052100704018.5 Apat-0541007044.520.5 Bogo-599510070244.5 CMS-24422520225 CMS-2442100283511 CMS-2443252081.8 CMS-244310046122.1 CMS-24431007015.53.3 Apat-006810021256.7 Apat-00671002115.56.0 Apat-006610021153.5 Apat-006410021257.8 CMS Endcap size (30x30x220 mm^3, tapered)ALICE size (22x22x180 mm^3, rectangular) Summary for all measured crystals * After 3 weeks of recovery,xtal was irradiated again *

19. V. Kachanov IHEP, July 28, 2004 The progress in PWO radiation hardness produced in Apatity during last two months is very good even for EE size crystal The behavior of the PWO crystals produced in Bogo and Apatity under irradiation looks very similar. More measured crystals are needed to optimize technology in Apatity Very good collaboration between North Crystals, IHEP and Khurchatov play the main role in these measurements. Conclusion

20. V. Kachanov IHEP, July 28, 2004 Plans Continue of the investigation of the Apatity crystals: - Long time irradiation (weeks, month) - Recovery during weeks - High doze rate measurements Irradiation by high energy electrons and pions using IHEP accelerator (November 04, one week run)