1. Koji Ueno National Taiwan U. 2003/2/13 @PSROC
Status of SVD2 upgrade
Koji Ueno
National Taiwan U.

2. Outline Features of SVD2 Flex saga Schedule & accident Conclusion
Smaller beam pipe & more Si layers
TTM( see Jerry’s talk) & Flex: done by NTU.
Flex saga
Low yield & spares
Schedule & accident
Beam pipe was broken
Conclusion

3. Features of SVD2 Smaller beam pipe R = 2 cm --> 1.5 cm.
Originally 1 cm was planed.
More silicon layers 3 --> 4.
Originally 5 layers were planed.
Radiation-hard front-end electronics.
Up to 10 MRad is tested OK.
Z trigger.
Necessary to remove a beam-gas event.

4. Belle SVD2 246 Double-sided Silicon Strip Detectors (DSSDs).
Each DSSD has 512 z strips and
512 phi strips.
Total no. read out is 250 k.
It is reduced to 110 k by ‘ganging’.
Ganging is done by FLEX.

5. SVD2 system

6. SVD1.x dose

7. TTM & Flex NTU is responsible for TTM & Flex. TTM  see Jerry’s talk.
We finished them in spring, 2002.
They are now used in 1/10 system without a problem.
We need a spare Flex and SVD to prepare for an “accident”.

8. Z-R trigger

9. Efficiency for 3-out-of-4 layers

10. Ganging in FLEX. FLEX DSSD Wire-bonding on Si and FLEX pads. Z strip
Read out
Signal
Signal

11. Ghost track due to ganging

12. Flex saga Flex task was supposedly easy.
Flex was in a crisis a year ago: low yield, bad wire-bonding, repair etc.
Laser beam was used to repair shorted lines to meet a deadline.
Only small no. of companies can make a Flex in the world.
Exchange of Flex info. among Belle, D0 and CDF.

13. Laser surgery of shorted wire
The shorted wire is fixed by laser.

14. Wire-bonding
25 mm wire for bonding.

15. SVD2 schedule

16. Integrated luminosity

17. Peak luminosity of Belle & BaBar

18. Space Shuttle Columbia accident

19. SuperKamioka in repair

20. Broken beam pipe

21. Installation of 1.2 SVD
HOM resonant heating
Installation of 1.4 SVD
Trouble of He cooling system

22. The SVD2 first cosmic ray muon event
Nov. 15, 2002

23. Conclusion
SVD2 upgrade has a successful 1/10 system test. Has seen the 1st CR event.
It is likely installed in summer, 2003.
It aims for a higher luminosity.
We have to prepare a spare SVD and a spare Flex for an accident.