Contents:

1
Monitoring of Radiation Damage of Si
Yongdok Ri _at_ Tokyo Metropolitan Univ.

• Contents
• Radiation dose at Si
• Method for monitoring of Radiation Damage of Si
• Some plots from 04 pre-shutdown data
• Summary and Future plan

2
Radiation dose at the Si
Radiation dose at the Si is estimated to be
1.9Mrad/year
Si Y distribution
Radiation dose damage the silicon detector after
a long period operation.
increase the dark current
fluctuate the pedestal of strip
Si Y (mm)
radiation dose is large at beam center
3
Pedestal and RMS of Si each strip
far beam center
near beam center
Pedestal
Pedestal
Day 2004
Day 2004
Pedestal RMS
Pedestal RMS
Pedestal is stable each strip. Although
fluctuate, Pedestal RMS doesnt increase.
4
Effect of the degradation on Si
(done by S.Kato)
Simulation of Si Degradation
change for number of events and charge in 1
cluster
Data
Smearing the pedestal
5
Monitoring of Rad Damage of Si using Fiber
check the mean charge deposited in Si with events
triggered by fiber

• Move the fiber on monitoring position
• Check the mean charge of 10 strips behind of the
  Fiber

Y position
charge with 1 cluster
6
cluster mean charge of Si triggered by fiber
Fluctuation of mean charge
Cluster charge
near beam center
4.0mm 3.1 3.5mm 4.3 3.0mm 3.3 2.5mm
2.2 2.0mm 1.9 1.5mm 2.8 1.0mm
1.4 0.5mm 2.1
0.0mm 1.6 -0.5mm 1.7 -1.0mm 1.9 -1.5mm
2.2 -2.0mm 1.3 -2.5mm 1.6 -3.0mm
3.5 -3.5mm 4.4 -4.0mm 3.5
Cluster charge
far beam center
Mean charge is stable. Fluctuation is 4.4 at the
maximum.
Day 2004
7
Linearity between Si Fiber
Data taken on 07/Mar
ysi(mm)
yfiber stepping motor count ysi mean
triggered by fiber
Error Fiber1mm/sqrt(12) SiRMS/sqrt(entries)
Slope is unity within error.
Slope is unity for other data sets
(25/Feb,24/May,11/Aug).
yfiber (mm)
8
Summary and Future plan

• Summary
• Radiation dose damage the silicon detector after
  a long period operation.
• Monitoring of Radiation damage of Si (04
  pre-shutdown data)
• the Pedestal and Pedestal RMS is stable each
  strip.
• the mean charge triggered by fiber is also
  stable. (fluctuation within 4.4)
• Linearity between Si and Fiber is good.
• Future plan
• continue the monitoring of radiation damage of Si
• Proper data taking every one month with 4.0mm,
  0.5mm step