[Halld-cal] updated FCAL mc response study

[Richard Jones]

Hello Matt,

I understand your concern that something has changed in the MC, but other
things could have changed as well, for example the cluster algorithm in the
fcal or the nonlinear correction applied to the reconstructed fcal cluster
energy. Any of these would change the behavior of the results I show.

Do you have a technical note to show what was done and the details of the
simulations that were used?

-Richard Jones

On Mon, Mar 25, 2019 at 7:11 AM Shepherd, Matthew <mashephe at indiana.edu>
wrote:

>
> Hi Richard,
>
> My understand is that you have reproduced the effect that I originally
> documented:  the energy response of the FCAL in the MC somehow changed and
> is now not correctly calibrated.  This is the original observation that
> motivated the issue.  From what I can tell, you seem to have verified that
> there is a problem.
>
> This problem was first documented in this log entry:
>
> https://logbooks.jlab.org/entry/3621347
> <https://gcc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Flogbooks.jlab.org%2Fentry%2F3621347&data=02%7C01%7Challd-cal%40jlab.org%7C0be6acac2cf4485272ff08d6b11512f4%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636891101422090006&sdata=a4NSv723KuYHtzd%2FuRNdq9B5XxcIlhE3Jgpn%2F%2Bd0fSo%3D&reserved=0>
>
> What I really wanted to know is:  why did the response of the FCAL in the
> MC change?  For this, we have seem to have no answer.
>
> So, we can retune the MC calibration of FCAL and mark the issue as
> "resolved."  But without understanding the reason the issue emerged, then
> it may sneak up again.
>
> Matt
>
>
> On Mar 23, 2019, at 4:39 PM, Richard Jones <richard.t.jones at uconn.edu>
> wrote:
>
> Hello Matt and all,
>
> I have updated my FCAL mc response study to single-photon events (0-8 GeV)
> in the forward direction. This shows the final adjustment in the energy
> scaling factors in hdgeant and hdgeant4. Unless I hear something to the
> contrary, I consider the energy scale issue reported on github
> Jeffersonlab/hdgeant4 to be resolved, if someone could agree and make it as
> resolved.
>
> Also shown in the updated report is a new timing comparison study, where I
> used the position recorded for the fcal shower together with the mc
> generated vertex information to produce a time-of-flight corrected shower
> time, which should be zero if the reconstruction and simulation are
> consistent. Notice that there is still a residual time-walk that we might
> want to understand and correct.
>
> https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=3852
> <https://gcc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fhalldweb.jlab.org%2Fdoc-private%2FDocDB%2FShowDocument%3Fdocid%3D3852&data=02%7C01%7Challd-cal%40jlab.org%7C0be6acac2cf4485272ff08d6b11512f4%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636891101422100193&sdata=s3GVouGzbvbn0P%2BcCt4tjyXELRVwgs9vugKr9EzHyu4%3D&reserved=0>
>
> -Richard Jones
>
>
>
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