1. Module Failures on Rods

2. Current Failures of Modules on Rods
UCSB
1 module (6662) had a saturated channel on rod during production exercise
1 rod had three modules (6046, 6264,5850) with saturated channels and one module (6503) with high current during production
FNAL
1 module (4047) had saturated channels on a non-production DS rod
1 rod had three modules (8241, 8242, 8244) with saturated channels on a non-production rod

3. UCSB Rod #1 Channel 67 saturated on rod, confirmed on ARCS stand
After plucking PA-Sensor wire bond, APV acts like open
Channel a regular pinhole
Visual inspection shows damage to channel on both sensors
Defect in manufacturing, same sensor batch
Pinhole is type of failure we are expecting during burn-in

4. UCSB Production Rod
3 edge channels failed on 3 modules (Positions 1, 2, 4) on one production rod
Modules failed on SRT, with old DAQ/CAEN controller software and new interconnect cards
All three saturated channels confirmed during ARCS tests
1 of 3 channels show visible damage to saturated channel on APV
One additional module has increased bias current but no new bad channels
Input to APV
Beginning of PA

5. UCSB Production Rod
All 3 channels stay saturated when PA-sensor bond pulled
For 2 modules without visible damage to APV, noise on neighboring channels disappeared with wire bond pull
Appears blown APVs driving noise into sensor
No extra current in LV or HV
Bonded functioning APV channel to sensor channel that was connected to blown APV channel
All 3 sensor channels ok, no pinholes or noisy channels
On module with visible APV damage, bias current increased to 12 mA
Now module fails bias current requirements

6. UCSB production rod
On module with high current but with no new bad channels, a burn mark was found on the corner of the second sensor on the metal where the numbering is
It is not clear to me how this could happen
Leads me to believe failures are due to something on the high voltage
Guard Ring
Outside Edge Metal

7. FNAL DS Rod 1 module had multiple saturated channels on a DS rod
Module failed on MRT with old DAQ/CAEN controller software and old interconnect cards
Extremely high current-10 mA at 40 V
Initially, channels have blown APV channels in first ARCS test
During subsequent ARCS tests, more blown APV channels develop

8. FNAL SS6 Rod
Multiple channels fail on 3 modules (Positions 1, 2, 4) on non-production rod
Modules failed on MRT with updated DAQ/CAEN software and old interconnect cards
Rod tested multiple times previously with no problems
All three modules’ faults confirmed on ARCS stand
Visible damage seen on APV for one of the modules

9. FNAL SS6 Rod Module 8241- APV channels 283-285 dead
Module draws up to 10 mA

10. FNAL SS6 Rod
Module APV channels , dead + noisy channels
Module draws up to 4 mA

11. FNAL SS6 Rod
Module APV channels 62-64
Module draws up to 8 mA

12. Summary/Conclusions
Modules are recently developing dead APV channels on rods but no commonality
Both DS and SS rods effected
Two rods have positions 1, 2, 4 effected
At UCSB always single edge channels; at FNAL groups of channels in middle of modules
On some module increased current seen, others no increase seen
1 tested on SRT, 2 tested on MRT
2 tested with old software/1 tested with updated software
2 rods had old interconnect cards, 1 rod has new ones
1 rod had retrofitted modules, 2 rods had non-retrofitted modules
Failures occurs at approximately the same time after large number of rods tested at both sites