Re: draft note on calibration systematics

[Elton Smith <elton@jlab.org>]

HI Andrei,

Thank you so much for your comments on the draft. I have incorporated your
suggestions and references.

I will also take a look at the new file at 60 MeV, and perhaps update the
document with this information. For now, I have gone ahead and posted the
note with previous information.

Cheers, Elton.

On Tue, 30 Jun 2009 semenov@jlab.org wrote:

> Elton:
>
> First, I'll answer your questions:
>
> 1. In her simulations, Irina used "standalone" FLUKA2008.3 , and you can
> find the correct reference to fluka in our report 845 (references 2 and
> 3). In concern to reference to our simulation, we (Irina and I) plan to
> write a report on the issue; I hope to produce some version around July
> 10, so at the moment, you can use something like "I.Semenova, A.Semenov,
> Report on simulation of BCAL signals/resolutions to be published."
>
> 2. Attenuation length was 350 cm.
>
> 3. We did not use photons-to-photoelectrons conversion factor. We used
> "attenuated energy"-to-"mean number of photoelectrons" conversion factor
> of 45 phe/MeV that corresponds to expected SiPM-Kuraray fiber pair
> sensitivity (Important: please read my comments on the issue below.)
>
> 4. Irina generated the requested ntuples for 60 MeV photons at 90 deg:
>
> for the hit in the center of the module:
> /u/group/halld/Users/semenov/fluka/fluka_de_phot_90deg_60mev.hbook
>
> for the hit in the center of one cell:
> /u/group/halld/Users/semenov/fluka/fluka_de_phot_90deg_60mev-shift.hbook
>
> Actually, Irina has a lot of energies/angles combinations done, and she
> will load the files on group disk as soon as she will have group
> privileges.
>
> And now, the comments/corrections to the report itself:
>
> 1. Irina's last name is "Semenova" that is a Russian female version of my
> last name, and for many reasons, it's better to use correct spelling. In
> this simulation, the most of the job is done by her, so it's better to
> refer to us as "Irina Semenova and Andrei Semenov" (in the case of journal
> publications, it should be "Irina A. Semenova and Andrei Yu. Semenov" to
> identify us more definitely because my last name "Semenov" is very common
> in Russia). Also, I believe that it will be useful to include Irina's
> e-mail (stepi@jlab.org) for the e-mail exchange on this issue.
>
> 2. We did not use just conversion factor to calculate the number of
> photoelectrons from the "attenuated energy". From the "attenuated energy",
> we produce the mean number of photoelectrons for that energy, and we seed
> the number of photoelectrons according to a convolution of Poisson dist.
> with Gaussian dist.(to account to electron multiplication). Resulting Npe
> distribution represents the ADC spectrum you will have from your
> photodetector; you should use this Npe distribution for estimations of
> energy resolution from BCAL (NOT "ideal" deposited-energy or
> attenuated-energy spectra that do not include photostatistics! <- This is
> in concern to whole section 2.1)
>
> 3. I do believe that these "non-uniformity" issues are very close to the
> issues discussed by me and Richard Jones some time ago (see GlueX-doc-845,
> Section 6 and Figure 19). At least, the formulas and conclusions should be
> the same though the nature of "non-uniformity" might be a little bit
> different...
>
> Sincerely,
> Andrei
>
>
>
>
> >
> > Hi Andrei,
> >
> > Attached is a draft study on the impact of gain uncertainties on the
> > energy resolution using your ntuple files. Please take a look at it,
> > especially the section where I describe the simulation. In particular, I
> > have a couple of blanks that I would like to fill in (page 1):
> > 1. proper reference to you simulation and fluka
> > 2. attenuation length used
> > 3. conversion factor of photons into photoelectrons.
> >
> > Also, do you know when the file at 60 MeV, 90 deg, will be available?
> >
> > Comments or suggestions are very welcome.  Please send them to me today,
> > so I can post a first version to the portal tomorrow.
> >
> > Thanks, Elton.
> >
> > Elton Smith
> > Jefferson Lab MS 12H5
> > 12000 Jefferson Ave
> > Suite # 16
> > Newport News, VA 23606
> > elton@jlab.org
> > (757) 269-7625
> > (757) 269-6331 fax
>
>
>
>