# Presentation: 490077

## Cable and Mirror QC

- Howard Budd
- Rochester Meeting
- March 27 2007

## Cables 275-325

- Measured 275-325 This week
- More RMS than Expected
- I looked at both the the low cables and high cables with 20 times magnifier and could not see a difference
- Not clear what is going on

## Cables 275-325

- However, only 2 cables failed the requirement of  fiber< 0.9*average
- 0.885 but could not see a problem
- 0.87 but could see a bright spot in the fiber so it is a hardware failure too

## ODU QC 

- We are at the point were we need to ship ODUs to Tufts
- SO we need a procedure and criteria
- The criteria is:
- If one fiber is <0.9*mean for that fiber number the ODU fails
- I stated this at the group meeting
- This was the CMS criteria
- We can lower this requirement if we need to without much problem, but one should decide on a number
- Start with this criteria
- In the QC files measured to cable 325 we have
- 271 cables with 11 optical failures
- Optical failure rate is 4%

## ODU QC

- The Cable QC program writes out 2 ASCII files
- Bad Cable file
- Channel or channels that fail and its normalized value
- We will put in if we can see a visual reason for the failure
- Good Cable file – written out it ASCII file
- Cable number
- Normalized cable mean (mean set to 1)
- The normalized transmission is the QC cut
- Normalized cable RMS transmission
- Normalized lowest channel
- Average Transmission
- Remember we still have the QC data file

## Cable QC

- We put this in a EXCEL file and add 2 columns
- Check off if the cable has been put in the shipping box
- Comment column
- Can put in the results of the visual inspection
- We have been continuing visual inspections, but what we might modified this if we are not learning anything from the visual inspection.
- Dan suggested the techs look them during optical QC
- In fact the cable may fail for some other reason and that will be put in here
- Cable could be used for some other reason

## Cable QC

- The file the techs will manipulate could either be electronics or paper
- I would prefer that it would be electronics, but it should be easy for the techs to work with
- When shipping the cables, it may be easier to check off a sheet of paper
- In CDF & CMS, we had travelers for all the megatiles
- In CMS we had a book case filled with these travelers
- They were never looked at after the megatiles was assembled
- These travelers will probably be or have been thrown away
- (For CMS the QC data still exists)
- Cables sheet -  we will add 2 columns
- Light tightness test – pass/fail
- Order test – pass/fail

## Mirroring QC

- In CDF, CMS  Eva Skup QCed the mirroring
- For D0 Eric Ramberg QC Eva’s mirroring
- He used the Lab 6 scanner
- Not sure if he scanned the or measured them at one point.
- Eileen has never really be the one to do the QCing of her mirroring
- However, she clearly wants to do it

## Mirror QC

- When D0 was QCing the mirroring, she setup a apparatus to compare with Eric Ramberg’s test
- Illuminating the fiber at one point with a UV lamp
- The illumination is done with a very small slit
- The place where to measure it near the end is flexable
- Clear end is read out with a pin diode/picoammeter
- Standard measure with mirror and cut mirror off with 45 degree cut and paint black.
- (I think that everybody does this)

## Mirror QC

- Eva measured the fibers at various points and extrapolates to the end of the fiber
- Developed by John Mansour during CDF
- The apparatus to do this does not exist anymore
- Note, Eileen and I just looked at Eva data for CMS and the average reflectivity was 83%. (Done for testbeam paper)
- For our measurement I showed at the breakout session at the Director’s Review Dan measured the fibers using the MINOS scanner
- I took the fit and extrapolated it to the end of the fiber
- Both of these methods probably got about the right reflectivity because of the extrapolation to the end of the fiber

## Mirror QC

- Eileen’s setup uses UV lamp, picoammeter and measures at one point
- Does not agree well with the MINOS setup

## Mirror QC

- My guess is her problem is the stability of the UV lamp
- She says this is the same lamp that lab 6 setup uses
- So I’m a bit reluctant to try to get the lab 6 setup going as we might have the same problem with it
- Plan
- Eileen will test the same mirrors with her setup and with a setup at Lab G which consists of a 4” square tile and a source. The measurement with the 4” tile will actually be a measurement 2 inches from the mirror. She will compare these 2 measurements. When one of the measurements makes sense, she will compare one of these measurements with the MINOS scanner measurement

## Mirror QC 

- She will then use either her setup or the tile and source setup to QC the mirror.
- The setup might not give the exact mirror reflectivity.
- However it should be able to tell if the reflectivity changes
- In some writeup (like was just requested for CMS) we want to quote the actually reflectivity, so we want a correlate the QC measurement with the actually reflectivity.