1. May 03P. Lecoq CMS/ECAL Crystal Cutting Status Paul Lecoq LHCC Referees CERN, 19 May 2003

2. May 03P. Lecoq CMS/ECAL Annealing to reduce tensions At high temperature crystal lattice tends to re-organise with time. Annealing at a temperature close to melting point with a very low thermal gradient has been used to reduce mechanical tensions. For original boules –Ø32/35x300mm 3 for EB –Ø35/45x300mm 3 for EE the annealing time is four days and has been working well in production conditions.

3. May 03P. Lecoq CMS/ECAL Annealing to reduce tensions For large boules –Ø60/68x300mm 3 ”two-in-one” –Ø75/85x300mm 3 ”four-in-one” the annealing would require ten days which is prohibitive in time, energy and gives time for crystal defects to migrate, impairing the optical transparency

4. May 03P. Lecoq CMS/ECAL Locating large boules in annealing ovens  The annealing ovens were designed to tightly match original EB and EE boules because of stringent gradient conditions  New large size boules with same useful length cannot take place in the furnaces  A new solution has to be found: –Reduce mechanical tensions at the growth –Develop smooth cutting technology

5. May 03P. Lecoq CMS/ECAL Progress on cutting large ingots  5 ovens have been dedicated to R&D on cutting large ingots : –Optimization of the shape in cone-cylinder transition –Optimization of the doping profile to increase lattice plasticity in critical parts –Optimization of the growth regime (speed, thermal gradient) in critical parts All these actions give positive results, and the ingots are now less stressed, even before annealing

6. May 03P. Lecoq CMS/ECAL Barrel production strategy  Growth of large ingots 68 and 85mm is now very successfull and reproducible  Annealing of these large ingots is not possible in the production annealing ovens, which leads to difficulties in cutting them  Technical problems for cutting large ingots are about similar for  =65mm (2/1) and  =85mm (4/1) ingots Go to  =85mm ingots when industrial cutting technology in production mode

7. May 03P. Lecoq CMS/ECAL *123  Large boules have to be put to length before annealing because of furnace dimensions  Cutting un-cured boules is very delicate and a rotary method is used to keep some symmetry  The cutting wire is slowly fed down (1 to 2 to 3) while the boule rotates with the help of a cam to keep a constant height (*) End cut with diamond wire M. Lebeau Work well on optimized ingots but slow process Problems of reliability : too frequent wire breaks

8. May 03P. Lecoq CMS/ECAL Rotary cut before annealing

9. May 03P. Lecoq CMS/ECAL Simplified Rotary Cut: The Square Cut  New optimized ingots are tolerant to a simplified rotary cut  Instead of continuous cut during ingot rotation, ingots are mounted in square holders allowing radials cuts at fixed angles of 0°, 180°, 90°, 270°  This method can be used with a diamond disk instead of a wire, with a considerable gain of time  If used in a sweep mode, the capacity of the machine would allow to cut 4 to 5 ingots at a time

10. May 03P. Lecoq CMS/ECAL Square end cut 68mm

11. May 03P. Lecoq CMS/ECAL Square end cut 68mm

12. May 03P. Lecoq CMS/ECAL Square end cut 68mm

13. May 03P. Lecoq CMS/ECAL Square end cut 85mm

14. May 03P. Lecoq CMS/ECAL Square end cut 85mm

15. May 03P. Lecoq CMS/ECAL Square end cut 85mm

16. May 03P. Lecoq CMS/ECAL ac a longitudinal cut is performed before annealing to 1/3 of Ø it affects the boule whole length in a symmetry plane annealing proceeds for four days the cut is completed to full Ø Good success on 85mm boules but not practical with the wire cutting machine Good success with high speed with diamond disk in sweeping mode Longitudinal cut M. Lebeau 85 28

17. May 03P. Lecoq CMS/ECAL Longitudinal and end cuts before annealing Wire machine

18. May 03P. Lecoq CMS/ECAL Longitudinal cut after annealing Wire Machine

19. May 03P. Lecoq CMS/ECAL Longitudinal cut after annealing Wire Machine

20. May 03P. Lecoq CMS/ECAL Longitudinal cuts before annealing Diamond Disk, sweeping mode

21. May 03P. Lecoq CMS/ECAL Final Cut after annealing Diamond Disk, sweeping mode

22. May 03P. Lecoq CMS/ECAL Final Cut after annealing Diamond Disk, sweeping mode

23. May 03P. Lecoq CMS/ECAL Fractioned longitudinal cuts 2-in-1 and 4-in-1 boules were successfully cut using the fractioned longitudinal cut method, with intermediate 4 days’annealing

24. May 03P. Lecoq CMS/ECAL Conclusions  Large progress in stability of ingots by combination of different actions –Yield is high enough for 68mm ingots to install the technology in production line –Some more optimization needed for 85mm ingots  Wire cutting machine works but the process is too slow and there are too frequent wire breaks (not completely understood)  New optimized ingots allow diamond disk machines to be used  Square endcuts and longitudinal precuts can be made before annealing with this method  Using the machine in sweeping mode allows much faster process  2 LBG disk machines have been ordered and will be delivered to CERN mid June and installed in Bogoroditsk in July  This will result in a 6 months delay in the production capacity increase, originally foreseen in the first semester 2003

25. May 03P. Lecoq CMS/ECAL Simulation delayed production 3000 in Q1-03 3000 in Q2-03 5100 in Q3-03 6600 in Q4-03

26. May 03P. Lecoq CMS/ECAL Production Scenario with