[Primexd] FCAL gain/energy calibration

Mon Apr 13 21:57:28 EDT 2020

Drew & Matt,

Yes indeed, there is an issue with the tracks when they are available which somehow "corrupt" the pi0 skim (src/plugins/Utilities/pi0fcaltofskim/). I thought initially it is a problem with TOF but I think now the matching is not working. A couple of weeks ago, I asked Bene/Simon/Sasha about the pattern bellow

[cid:f22f2a4f-e62e-4a46-b5a7-f0c079b25066]

which only appears when I am removing clusters with matching tracks in the chambers.

To answers your question more specifically when I am requesting two "photons" I am using all clusters with and without matching tracks in the chambers but that's not true when the chambers are ON in fact. I will produce a couple of runs with the matching turn off to see if it is solving this problem (for both BCAL & FCAL).  Also, I still do not understand why this should change the gain and prevent from improving the resolution.

tks ig.

________________________________
From: Drew Smith <andrew.p.smith at duke.edu>
Sent: Monday, April 13, 2020 9:20 PM
To: Igal Jaegle <ijaegle at jlab.org>; Shepherd, Matthew <mashephe at indiana.edu>
Cc: primexd at jlab.org <primexd at jlab.org>
Subject: [EXTERNAL] Re: [Primexd] FCAL gain/energy calibration

Hi Igal,

What is your criteria for selecting events with only 2 gammas detected? Are you using tracking at any stage? Like Matt pointed out, it looks like the jumps in your pi0 mean vs. run number plot correspond to the runs where the drift chambers were turned on. If you direct me to the plugin that produced your skims I can also help with the investigation.

Best,
-- Drew
________________________________
From: Primexd <primexd-bounces at jlab.org> on behalf of Igal Jaegle <ijaegle at jlab.org>
Sent: Monday, April 13, 2020 2:36 PM
To: Shepherd, Matthew <mashephe at indiana.edu>
Cc: primexd at jlab.org <primexd at jlab.org>
Subject: Re: [Primexd] FCAL gain/energy calibration

All,

I look in further detail for the He runs into the gammagamma invariant mass when only two "photons" are detected. At the start of the run, the invariant mass is looking good and is similar to the Be run.
[cid:1de84d1e-5ef9-4d1e-a541-8dfe3b89e94c]

but after a few runs, it is looking like this, a peak is appearing at 75 MeV and is coming from the inner ring/square.

[cid:98776d0f-cac4-4cf9-9c2f-427ce6c08245]ttks ig.
________________________________
From: Igal Jaegle <ijaegle at jlab.org>
Sent: Monday, April 13, 2020 2:27 PM
To: Shepherd, Matthew <mashephe at indiana.edu>
Cc: primexd at jlab.org <primexd at jlab.org>
Subject: Re: [Primexd] FCAL gain/energy calibration

Thank you Matt for your comments. In principle, I am doing the QC only on "good" physics runs (target filled) but there is something indeed fishy with the He data and/or hopefully only with the new pi0 skims that I produced. For example, after a couple of iteration, I am able to improve dramatically the pi0 resolution for the Be run and for the beginning of the He run, but for the rest of the He run, the resolution is barely improving after each iteration.

All,

In the meantime, I implemented new ranges but there is a subdivision that needs to be done.

tks ig.

________________________________
From: Shepherd, Matthew <mashephe at indiana.edu>
Sent: Monday, April 13, 2020 11:23 AM
To: Igal Jaegle <ijaegle at jlab.org>
Cc: primexd at jlab.org <primexd at jlab.org>
Subject: [EXTERNAL] Re: [Primexd] FCAL gain/energy calibration

Hi Igal,

These plots are interesting, particularly the discrete jumps.  I went back to to look at the logs and some boundaries, I think the ones you marked, correspond to target empty/refill, right?

Without run numbers, it is hard to do detailed detective work, but I recommend taking a look at the He 1 period more closely.  There is one anomalous point where the pi0 mass is high that I predict might be run 61462.  At this point, by reading the eLog, it appears that there was an attempt to run with CDC in the data stream.  That was then abandoned because RootSpy wasn't working properly, and running continued, perhaps restoring pi0 mass back to its previous value.  Then the next day Sasha got CDC working in the data stream and again the pi0 mass returned to the high value.

Likewise, there are two jumps at the end of the He 3 run period that you have marked,  These appear to coincide with particular changes to include/exclude the FDC in the readout.

Naively, the gain of the FCAL shouldn't change whether or not the chambers are read out.  Perhaps it is purely coincidence, but I have a little concern you might be treating a symptom instead of getting at the root cause by adjusting gains.

Could your plots (perhaps backgrounds) be sensitive to presence/absence of tracks when the CDC or FDC hits appear/disappear?

Matt

On Apr 11, 2020, at 11:28 AM, Igal Jaegle <ijaegle at jlab.org<mailto:ijaegle at jlab.org>> wrote:

PrimeXDeurs,

The QC shows that two new gain tables should be changed/added for the following run ranges: 61482-61570 and 61789-61910

tks ig.

<Mean_vs_run_number_eta.pdf><Width_vs_run_number_eta.pdf><Mean_vs_run_number_pi0.pdf><Width_vs_run_number_pi0.pdf>_______________________________________________
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