[Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1

Fri Nov 5 15:35:28 EDT 2021

Hi All,

Attached I have a low level plot from the cosmic run while the UV GEMs were
in BB. Unfortunately we do not have any results with good statics, but you
can see that the pattern is starting to emerge around the edges. I am
certain that if this had more statistics it would look just like the
results from the test lab.

So overall we have a few confusing factors. First, the UV to XY
transformation is not scaled correctly, so the dimensions are not correct,
and second there are some noise that creates effects around the edges. But
none of this is unusual and the data looks exactly like the UV GEMs
currently in BB and I have no concerns.

Best,
Sean

On Fri, Nov 5, 2021 at 3:17 PM Andrew Puckett <puckett at jlab.org> wrote:

> Here is the hit distribution for hits on good tracks for the U/V layers
> from run 11298 (5 uA on LH2, SBS-1 kinematics).
>
>
>
> The first plot is for the 2nd U/V layer.
>
>
>
> In this plot, the y coordinate extends all the way to 20 cm on the
> negative side. On the positive side the edge of the active area is cut off
> by the BigBite magnet acceptance, among other things.
>
>
>
> The second plot is the 1st U/V layer.
>
>
>
> In this 2nd plot, the y coordinate distribution is cut off on both sides
> by the magnet acceptance. Since the BigBite GEMs are offset about 3 cm to
> beam left from the center of the magnet gap, the center of the magnet
> acceptance is at about -3 cm in the local GEM coordinates.
>
>
>
> Some of the “holes” that you see are actually artifacts of the combined
> effect of using a 4-hit minimum requirement for tracking and the images of
> dead areas from other layers, some of the “holes” represent dead areas
> within the layer itself.
>
>
>
> But as far as we can tell the active area size is in fact +/- 20 cm
> horizontally, and that is what we assume in the analysis code.
>
>
>
>
>
> *From: *Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Liyanage,
> Nilanga K (nl8n) <nl8n at virginia.edu>
> *Date: *Friday, November 5, 2021 at 3:04 PM
> *To: *Jeffas, Sean (sj9ry) <sj9ry at virginia.edu>
> *Cc: *sbs_gems at jlab.org <sbs_gems at jlab.org>
> *Subject: *Re: [Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1
>
>
>
> But I thought the active area goes to +/- 20 cm, right ? why is this edge
> a few cm inward from there ?
>
>
>
> It this what we are seeing in the other UV chambers ?
>
>
>
> Best
>
>
>
> Nilanga
> ------------------------------
>
> *From:* Sean Jeffas <sj9ry at virginia.edu>
> *Sent:* Friday, November 5, 2021 3:01 PM
> *To:* Liyanage, Nilanga K (nl8n) <nl8n at virginia.edu>
> *Cc:* Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>; sbs_gems at jlab.org <
> sbs_gems at jlab.org>
> *Subject:* Re: [Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1
>
>
>
> Hi Nilanga,
>
>
>
> This is the edge of the active area. The size of the graph is larger than
> the actual active area. The hits outside of the active area are just noise
> that got reconstructed improperly. Normally we do not see this with an XY
> GEM because in that coordinate system even fake hits must fall inside the
> active area. But if we have a 2D correlation that is not real in the UV GEM
> then it is possible for that to get reconstructed in an impossible
> position. This is because of the UV geometry. Hence why only UV GEMs will
> have noise that shows up outside of the active area.
>
>
> Best,
> Sean
>
>
>
> On Fri, Nov 5, 2021 at 2:55 PM Liyanage, Nilanga K (nl8n) <
> nl8n at virginia.edu> wrote:
>
> Hi Sean
>
>
>
> Yes, may be the mapping is correct.
>
>
>
> But I have a question: What gives rise to the  drop along the sharp
> straight lines at roughly + and - 160 mm ? Is it the trigger scintillator ?
>
>
>
> Best
>
>
>
> Nilanga
>
>
>
>
> ------------------------------
>
> *From:* Sbs_gems <sbs_gems-bounces at jlab.org> on behalf of Sean Jeffas <
> sj9ry at virginia.edu>
> *Sent:* Friday, November 5, 2021 2:15 PM
> *To:* Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
> *Cc:* sbs_gems at jlab.org <sbs_gems at jlab.org>
> *Subject:* Re: [Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1
>
>
>
> Hi All,
>
>
>
> Here are the results using 2 hit minimum clusters. I think the UV GEM
> mapping looks fine. However there are a lot of areas with missing strips
> adding up (I count at least 7 areas). It looks to be about 5-10% of the
> active area in missing strips. Since we have time, as Bogdan suggests, I
> will try to fix as many as I can.
>
>
>
> Best,
>
> Sean
>
>
>
> On Fri, Nov 5, 2021 at 1:56 PM Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
> wrote:
>
> Hi Sean,
>
> Maybe you are right, but please double-check carefully without assumption
> that just because you duplicate the same mapping for the other chambers,
> that you got all your mapping right.
>
>
>
> I see a lot of patterns in both 2D hit map and 1D hit distribution that
> make me suspect that there is a mapping issue, though I am not prepare to
> bet my life on this
>
>
>
> Best regards
>
> Kondo
>
>
>
> *From:* Sean Jeffas <sj9ry at virginia.edu>
> *Sent:* Friday, November 5, 2021 1:48 PM
> *To:* Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
> *Cc:* Ezekiel Wertz <ewertz at email.wm.edu>; sbs_gems at jlab.org
> *Subject:* Re: [Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1
>
>
>
> Hi Kondo,
>
>
>
> The UV layer does not have a mapping problem. It is an exact copy of the
> mapping from BB, which is proven to be correct. I believe the pattern and
> all the hits outside the active area are just noisy strips that cause bad
> 2D correlations, since this is a low level analysis and does not have
> tracking to check that hits are true. Also notably, I just realized this is
> an old version that accepts 1 strip clusters, which certainly also
> contributes a lot to the noise that we see. It may be worth it to rerun
> with 2 hit minimum clusters.
>
>
>
> For the UV data, I see there are some strips missing, and an entire APV on
> the right most side. I looked at the GEM yesterday and did not see anything
> disconnected, and also the raw APV data did not show me that the APV was
> bad. So I am not sure if it is possible to fix all these missing strips. If
> we have time I can try replacing some APVs, but it will likely end up being
> more work than it is worth. Also I will note that the large missing area
> from one APV on the right side correspond to the top of the GEM, and would
> therefore be outside of the production cross section anyway.
>
>
>
> Best,
>
> Sean
>
>
>
> On Fri, Nov 5, 2021 at 1:26 PM Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
> wrote:
>
> Hi Zeke,
>
> I don’t think it is a big deal. Sean or John will probably fix it quickly
>
> Thanks
>
> Kondo
>
>
>
> *From:* Ezekiel Wertz <ewertz at email.wm.edu>
> *Sent:* Friday, November 5, 2021 1:24 PM
> *To:* Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
> *Cc:* sbs_gems at jlab.org
> *Subject:* Re: [Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1
>
>
>
> Hi Kondo,
>
>
>
> I am not as familiar with the UV layer mapping. So I'll talk to Sean about
> this. I'll also do some comparison with the BB UV layer mappings.
>
>
>
> Zeke
>
>
>
> On Fri, Nov 5, 2021 at 1:19 PM Gnanvo, Kondo (kg6cq) <kg6cq at virginia.edu>
> wrote:
>
> Hi Zeke,
>
> That is great. Thanks for these first results.
>
> It looks to me that there is a mapping problem with the UV layer.
>
> Please have a look at the pattern of the 2D hit map. Just a minor issue
>
>
>
> Best regards
>
> Kondo
>
>
>
> *From:* Sbs_gems <sbs_gems-bounces at jlab.org> *On Behalf Of *Ezekiel Wertz
> *Sent:* Friday, November 5, 2021 1:11 PM
> *To:* sbs_gems at jlab.org
> *Subject:* [Sbs_gems] [EXTERNAL] Fwd: Cosmic data for UV Layer and J1
>
>
>
>
>
> ---------- Forwarded message ---------
> From: *Ezekiel Wertz* <ewertz at email.wm.edu>
> Date: Fri, Nov 5, 2021 at 11:47 AM
> Subject: Cosmic data for UV Layer and J1
> To: <sbs_gem at jlab.org>
>
>
>
> Hi GEM folks,
>
>
>
> Attached you will find cosmic data and plots for the UV layer and J1.
> Taking cosmic data on the UV layer was priority, but we managed to get INFN
> J1 running as well. We took this data earlier this week. There were about
> 500,000 events.
>
>
>
> Other than a few strips that look not great, it looks like the UV layer is
> performing fairly well. Maybe Sean, Anu, or John has more to say about
> that.
>
>
>
> In regards to J1, each module on this layer has 2 shorted sectors. Which
> we see fairly clearly. However, there is a missing APV on the middle
> module. This was disabled because of connection problems that have since
> been better  understood. The top module has a partial or almost missing
> APV, this connection has since been remedied but needs to be checked. So
> this APV on the middle module is the last major thing that needs to be
> resolved for J1. There are some strips on the top and middle module that
> are partial and it needs to be understood if those are bad strips or
> partially disconnected APVs.
>
>
>
> So again the main result for this is the UV layer. But this is also a good
> starting place for J1. Also take note that the empty plots are simply
> because this plotting macro was not adjusted for 2 layers instead of 5.
>
>
>
> Best,
>
> Zeke
>
> _______________________________________________
> Sbs_gems mailing list
> Sbs_gems at jlab.org
> https://mailman.jlab.org/mailman/listinfo/sbs_gems
>
>
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