[Halld-cal] updated study of Fcal response in MC

[Gan, Liping]

Hi, Richard,


In your result, the energy deviation for the reconstructed photon in FCAL reaches more than 100 MeV. I would like to ask Ilya to comment on this since he has done a lot of simulations on calorimeter.


Liping


________________________________
From: Richard Jones <richard.t.jones at uconn.edu>
Sent: Tuesday, March 12, 2019 2:16 PM
To: Gan, Liping
Cc: Liping Gan; Matthew Shepherd; halld-cal at jlab.org
Subject: Re: updated study of Fcal response in MC

Hello Liping,

The response of the calorimeter itself in the MC does not have these two inflection points that you see in these plots. Those are coming from the interaction between the non-linear response in the simulation coupled with the (non-equivalent) non-linear corrections being applied in mcsmear and the cluster energy reconstruction. This plot shows the net effect of all 3 (MC + mcsmear + recon).

-Richard

On Tue, Mar 12, 2019 at 1:13 PM Gan, Liping <ganl at uncw.edu<mailto:ganl at uncw.edu>> wrote:

Hi, Richard,


Thanks for the excellent result. I just wonder if there is any explanation for the small bump at 1.5-2.5 GeV in you plots? Thanks!


Liping

________________________________
From: Richard Jones <richard.t.jones at uconn.edu<mailto:richard.t.jones at uconn.edu>>
Sent: Tuesday, March 12, 2019 10:37:29 AM
To: Liping Gan; Matthew Shepherd
Cc: halld-cal at jlab.org<mailto:halld-cal at jlab.org>
Subject: updated study of Fcal response in MC

Hello Liping and all,

At your suggestion, I went back and redid my study of reconstructed showers in the FCAL from MC, comparing hdgeant and hdgeant4, this time covering a larger energy range up to 8 GeV. For the results, see the latest document uploaded to docdb.

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%7C1c9c85584899471e0a0b08d6a7d3f4da%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636880926124919329&sdata=ARrpWMUnZo3pJKPZW8mjRkTl%2FN66TUGzdWThduEln8Y%3D&reserved=0>

Here is a summary of what I found.

  1.  I found a small bug in my fitting code that shifted the Ereconstructed down by 16 MeV relative to the generated in my earlier studies. This made the negative y-intercept in the Ereconstructed vs Egenerated appear worse than it actually is.
  2.  I adjusted the output from shower particles in hdgeant4 relative to hdgeant down by 0.8% as we discussed a the last calorimeter meeting. This change is visible in the new results. I now claim that the agreement in the shower energy response between hdgeant and hdgeant4 is very good.
  3.  With the new larger simulated energy range, my statistics of 100K events total is limiting my statistical accuracy in studying the non-linearity. Since there is no visible variation with polar angle seen in these individual plots, I added at the end a plot with the full statistics over the range 3-11 degrees, which has less statistical scatter and reveals the nonlinear behavior better.
  4.  Above 4 GeV there is a very large rise in the reconstructed energy. Overall the nonlinear correction needs work at both the low and high energy ends of the Fcal spectrum.

-Richard Jones
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