Status of SVD2 upgrade

Koji Ueno

National Taiwan U.

2003/2/13 @PSROC

Outline

Features of SVD2 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

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.

246 Double-sided Silicon Strip Detectors (DSSDs).

Each DSSD has 512 z strips and512 phi strips.

Total no. read out is 250 k.It is reduced to 110 k by ‘ganging’.

Ganging is done by FLEX.

Belle SVD2

SVD2 system

SVD1.x dose

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”.

Z-R trigger

Efficiency for 3-out-of-4 layers

Ganging in FLEX.

Z strip

DSSD

FLEX

Read outSignal Signal

Wire-bonding onSi and FLEX pads.

Ghost track due to ganging

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.

Laser surgery of shorted wire

The shorted wire is fixed by laser.

Wire-bonding

25 m wire for bonding.

SVD2 schedule

Integrated luminosity

Peak luminosity of Belle & BaBar

Space Shuttle Columbia accident

SuperKamioka in repair

Broken beam pipe

Installation of 1.2 SVD

Installation of 1.4 SVDHOM resonant heating

Trouble of He cooling system

The SVD2 first cosmic ray muon event

Nov. 15, 2002

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.