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[Xu Sun <sunxuhit AT gmail.com>]

Hi Gerard,

> About the connector screws, are these _part_ of the connector body (i.e. studs really) or are they separate screws that we could simply buy and use shorter screws and this problem would be resolved? Can you clarify please?

That's actually also my question to Mike or maybe Yi/Maowu. I am not sure if the screws are part of the connector or we could switch them to some shorter ones, since I only see the final assembled T-board.

Best,

Xu

On Tue, Feb 16, 2021 at 10:12 AM Visser, Gerard <gvisser AT indiana.edu> wrote:

Dear Xu,

   About the connector screws, are these _part_ of the connector body (i.e. studs really) or are they separate screws that we could simply buy and use shorter screws and this problem would be resolved? Can you clarify please?

Thanks,

     Gerard

---

From: Xu Sun <sunxuhit AT gmail.com>
Sent: Tuesday, February 16, 2021 11:02 AM
To: Capotosto, Michael <capotosto AT bnl.gov>
Cc: Visser, Gerard <gvisser AT indiana.edu>; Star-fst L <star-fst-l AT lists.bnl.gov>
Subject: Re: [Star-fst-l] Weekly FST meeting, Feb 15 8:30am (BNL time)

 

Hi Mike,

Thanks for the reply.

> “FST-V3.1-07 is too tight to be plugged in “ – Do you mean the connector/pins are too tight? I’m not sure how to address this, other than as you said going through a few insertion/removal cycles and hoping it loosens up.

Yes, I mean the connectors on the T-board are too tight for the pin to be inserted. I guess a few cycles of insertion/removal is what we are going to do before the test/experiment.

> “FST-V3.1-02 shows I2C error” – This could be a wire or pair out of place – I didn’t inspect these closely, but we should be able to buzz it out and confirm. If it’s not the cable the only other issue I can imagine is a bad temp sensor on the T-board putting out garbage data. I’d put my bet on the former.

We have used the same FST04 to test all the new purple cables and only FST-V3.1-02 gives the I2C error. Unfortunately, I couldn't do the test again since the pin on FST04 was bended by 07 and I am a little bit hesitant to plug any new purple cable into FST04 now. But it is most likely related to the cable itself.

> On Slide 4: “In modified ABC board: inner HV is applied through BNC-pin splitter and outer HV is applied by BNC => need confirmation from Mike.” – This is correct.

Thanks for the clarification.

> On Slide 5: This noise issue is odd as Gerard said. I think he’s right in that all we have to test here is for voltage on other pins where it should not be. However I’d expect the noise to disappear once the bias is dropped low enough or shut off. That one is a mystery to me.

Let me describe the issue we observed again. 

For FST18, we firstly did a noise run w/o any HV applied and both inner (with Si Sensor) and outer (APV only) behaves as expected. We repeated the noise run at 70V, nothing special happened. The problem is with inner HV when it is ramped to 140V, the APV5 (the output pins are probably OUTPUT4_P/N, but need double check) becomes noisy. After the problem appears, it stays even when HV is reduced. 

Another thing worth mentioning is, the "trigger" HV could be any value between 70 and 140V, since we only readout the module at 140V after 70V.

For the T-board part, in slide 3, the screws of the connector are conflicting with the MS and make the T-board non-flat. Do you have some shorter screws to use for that purpose?

We would like to send the GC26 and FST-V3.1-02 (maybe also 07) to you for the investigation. But before that, could you please send us another (or two) Gray Cables for the cosmic test stand? GC26 is still good to readout IST, and we would like to keep our cosmic test running until we have the replacement gray cable.

Best,

Xu

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