[Sbs_gems] [EXTERNAL] Question on pedestal plots

[Gnanvo, Kondo (kg6cq)]

Hi Sean,
Thanks for fixing the issue of pedestal shift.
Do you understand why it was the case? And also do you see any improvement in the layer performance after that fix?
I looked at the link you sent but it is hard to say, I am assuming that the run correspond to LD2 beam at 5 mA. Is that the case, bcase the efficiency dropped a little bit w.r.t the plots I was looking at yesterday for which I believe the beam current was 3 mA.

Best regards.
Kondo

From: Sean Jeffas <sj9ry at virginia.edu>
Sent: Saturday, January 22, 2022 7:16 PM
To: Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
Cc: Andrew Puckett <puckett at jlab.org>; sbs_gems at jlab.org
Subject: Re: [Sbs_gems] [EXTERNAL] Question on pedestal plots

Hi Kondo,

For point 2 I noticed that one backplane shifted it's pedestal today which is why you see that offset. I uploaded a new pedestal today. You should look at a more recent run, like this one:

https://logbooks.jlab.org/entry/3975713

The distribution for layer 1 is similar to all the UV layers.

Best,
Sean

On Sat, Jan 22, 2022 at 6:59 PM Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu<mailto:kg6cq at virginia.edu>> wrote:
Hi Andrew,
I was looking at some pedestal plots and I noticed two things,

1-) The difference between sorting and Danning method has this curve-like shape for the U-V strip layer that is not seen for the X-Y layers and the difference is quite significant compare to the common mode fluctuation itself. I looked at some earlier plots (run 13394) when we had all 4 U-V layers as well as the most recent one and it seems quite consistent.

https://logbooks.jlab.org/files/2022/01/3975625/summaryPlots_13455_BBGEM_ped_and_commonmode_50k_printme.pdf

https://logbooks.jlab.org/files/2022/01/3974078/summaryPlots_13394_BBGEM_ped_and_commonmode_50k_printme.pdf

2-) I also see for the V stripe of layer#1, the difference is more pronounced and I am thinking this might partly explain the lower efficiency we are seeing with this layer

I was wondering if there is any explanation for the discrepancy. Maybe there is something here that we can learn something from

Best regards
Kondo
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