sPHENIX MAPS tracker discussion

[Cameron Thomas Dean <cameron.dean AT cern.ch>]

Hi Ming,

>From the messages I saw from Jo timed to the cable swaps, I believe that he did run 600 Mb/s. We should note that I found out after this email that the cables we used were 8.8m long and not 8.0m long as we originally thought. This means there is more attenuation in the cable than an 8.0m long cable but less than the 10.0 m cables we use in the detector. We asked samtec to produce 7.5m and 8.5m long cables.

Cheers,
Cameron

 

From: sPHENIX-MAPS-l <sphenix-maps-l-bounces AT lists.bnl.gov> on behalf of Liu, Ming Xiong via sPHENIX-MAPS-l <sphenix-maps-l AT lists.bnl.gov>
Date: Friday, October 13, 2023 at 5:04 PM
To: schambachjj AT ornl.gov <schambachjj AT ornl.gov>, sphenix-maps-l AT lists.bnl.gov <sphenix-maps-l AT lists.bnl.gov>
Subject: Re: [Sphenix-maps-l] test of "short" SAMTEC cables

Hi Jo and Cameron,

Thanks for the update. From your measurements, it seems grounding could also play some roles.

  

Have you tried 600Mbps with these two short cables, any errors?

 

Cheers,

Ming

 

-- 

Dr. Ming Xiong Liu

P-3, MS H846

Physics Division

 

Office: 505.667.7125

Mobile: 505.412.7396

Los Alamos National Laboratory

 

 

From: sPHENIX-MAPS-l <sphenix-maps-l-bounces AT lists.bnl.gov> on behalf of SPHENIX MVTX <sphenix-maps-l AT lists.bnl.gov>
Reply-To: Jo Schambach <schambachjj AT ornl.gov>
Date: Friday, October 13, 2023 at 2:57 PM
To: SPHENIX MVTX <sphenix-maps-l AT lists.bnl.gov>
Subject: [Sphenix-maps-l] test of "short" SAMTEC cables

 

With the help of Cameron, I just tested one of the “short” Samtec cables wrt data transmission errors at 1.2Gbps. We used the telescope setup for that purpose.

I first verified that all staves of the telescope have no PRBS errors at 600Mbps with the “default” cables currently installed. This seemed to be OK.

I then programmed the RUs with the firmware that uses 1.2Gbps for the data transmission from the staves. With the default cables I saw PRBS errors at that speed in RUs 0, 9, 15, 18, and 21 (i.e. 5 out of 8 RUs), with the worst being 21 and 9.

Cameron then installed one of the shorter cables, but the first cable used had at least 2 of the 9 chips not lock to the transceiver on the RU.

A second cable worked OK with the transceiver lock, however, there were immediate PRBS errors on all of the chips. I tried increasing the operating voltage to 1.9V (from 1.8V), but got the same result. Increasing the driver current to its max also didn’t make a difference.

 

So this is not looking too good for the prospect of using higher speed readout from the staves….

 

Jo

 

--

Joachim Schambach

Oak Ridge National Laboratory

PO Box 2008

Bldg. 6000, MS 6368, Rm 205-C

Oak Ridge, TN 37831-6368

Phone: (865) 341-0694

Email: schambachjj AT ornl.gov

 

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