Sphenix-tpc-l mailing list

[Thomas K Hemmick <Thomas.Hemmick AT stonybrook.edu>]

Hi guys

2 cents...  

If you have continuity (resistance) & leakage current tests of an open GEM (where you can easily get the leads connected where you need) that proves EVERYTHING.  The issue once you stack GEMs is that you cannot perform a final continuity (resistance) test since the second lead of the meter cannot find the GEM surfaces (they are hidden).  Capacitance test is the poor-mans continuity test and is utilized when you cannot reach the GEM surface.  Capacitance requires that the GEM surface is electrically connected but does not require the lead of the meter to reach the surface.  So we must measure capacitance instead of continuity (resistance) once it become the only available option but it is not really necessary before that point.

Tom

On Mon, Apr 22, 2019 at 10:13 AM Oleg Grachov <oleggrachov33 AT gmail.com> wrote:

Dear Sourav,

For Alice we checked capacitance after assembling foil in chamber, before this the main criteria is a low leakage current. 

Oleg

Sent from my iPhone

On Apr 22, 2019, at 8:49 AM, Tarafdar, Sourav <sourav.tarafdar AT vanderbilt.edu> wrote:

Hi Oleg,

Thanks for clarification. Couple of comments     below based on your input

 

1. Is the method of stretching is gluing has been left out for the time being and will be added later ?

 

Stretching and gluing will be in separate document. This is QA document

I think then it’s better to leave out the text “framing “ from the section 6 header as it reflects only the testing . 

 

2. Other than  HV testing of GEM shouldn’t we also include the measurement of capacitance of the GEM in the testing procedure ? Usually for standard 10x10 GEM the capacitance is about 5.7 nF though I am not sure what it will be for the sTPC GEMs .  We might want to measure the capacitance of these GEMs both before and after framing. Also in the air and in N2 gas environment. Even better if we do it after placing the GEM in the experimental gas mixture but may be it will be over kill. 

 

Normally we measued capacitance after assembling chamber

You mean after framing or after putting together the module ? Checking the capacitance after assembling the module or only after framing the GEM is definitely needs to be done but also before we go through the assembly. Doing it also before assembly will make us sure that we are dealing with good GEMs and also will remove the pain of disassembling the module in case we find that a GEM is not good enough to be assembled. 

3. Also one can test the GEMs conductivity using multimeter. In principal it should show 0 nanosiemens with fluctuation of unto +/- 0.2 nanosiemens. This again can be done before and after framing the GEMs.

You will measure this during preparation for  leakage current  measurements

Sure ! Additional step of measuring it using multimeter before sending the HV will also give us an idea what we are dealing with. 

4. Do we really need to check all the 16 GEM sectors for leakage current at the same time or we can just do 8-9 sectors at one time and then go for rest of the sector ? This question is mostly because we have 10 channel pico ammeter so testing all the 16 sectors at the same time seems difficult.

No, you can measure any number of sectors one time

 

5. Checking the SMD load resistor . Any specific procedure to follow or just checking the resistor values using multimeter will be good enough ?

You will measure SMD load resistors during preparation for leakage current measurements, no any specific procedure (using multimeter will be good enough)

Thanks,

-Sourav 

On Apr 19, 2019, at 1:22 PM, William Llope <wjllope AT wayne.edu> wrote:

Hi tom and all

I missed the meetings this week, but did hear about the "QA documents" effort
from Oleg. I was unable to figure out what to do with a couple of the documents
he gave me (something about the NSLS-II?), but we did take a stab at the SOP
document.

Oleg wrote section 6, and I wrote the rest.
It is attached.

Any comments would be much appreciated - I don't yet have a good feel for
what is really needed here, so this version may be pretty bad!!

 cheers
     bill

> On Apr 18, 2019, at 2:11 PM, Thomas K Hemmick <Thomas.Hemmick AT stonybrook.edu> wrote:
>
> Hi Everyone
>
> Today's L2 managers meeting is pressing on us for the schedule of activities.  Since the practice session for the management plenary talks for the PD2/3 review are now scheduled for May 9, they would very much like all our action items (e.g. the new QA documents!) to be already available at that point.  This is a bit earlier than I had specified in yesterday's meeting when I was referencing the May 15 date for the L2 manager's review.
>
> Thanks,
> Tom
>

___________________________
W.J. Llope       Ph.D., Assoc. Prof.
http://wjllope.physics.wayne.edu/
Wayne State University, Physics    
666 W. Hancock, Room 347
Detroit, MI  48201
313-577-9805

<SOP_GemFrameAndTest_20190419.docx>