USCMS Tracker Meeting

1
U of R Status Report

• IV curve and second kink
• QA stand status - R poly measurement has been
  debugged

2
IV curve

• IV curve shows integrated leakage current for all
  strips
• If strips working properly the IV curve reaches
  plateau, stays constant until breakdown
• Ideally total leakage current would be expected
  to be around 500 nA for ST OB2
• In reality IV curve always goes up due to early
  breakdown some leaky strips

3
IV Curve
4
Strip Leakage Profile
5
Second Kink
Abnormal change
6
Together with strips
7
Leaky strips break together
Good Strip
8
Second Kink Voltages

• 30210431830707 NO
• 30210431830713 NO
• 30210431830715 weak 200V
• 30210431830718 weak 190V
• 30210431830801 obvious 185V
• 30210431830802 NO (vacuum)
• 30210431830803 obvious 190V
• 30210431830805 obvious 195V
• 30210431830808 obvious 190V

• 30210431830809 obvious 200V
• 30210431830810 obvious 160V
• 30210431830811 NO
• 30210431830812 obvious 175V
• 30210431830813 weak 185V
• 30210431830816 weak 175V
• 30210431830819 BAD strip 130
• 30210431830822 weak 185V

Out of 17 4 good 5 sort of OK 7 have 2nd kink
one BAD
9
Second Kink

• Second kink indicates partial breakdown.
• Contributing strips are not necessary qualified
  as bad strips though probably are not reliable at
  all.
• If bad leaky strip definition would be strip
  current 5 nA (currently 100 nA), ALL ST
  sensors will fail.

10
Status report on QA stand

• Noise while testing Rpoly was because of the way
  value of current was taken.
• Bug was found and fixed.
• Next would be optimization of the program
  eliminating not necessary delays and crosschecks.
• This doesnt interfere with testing in general.