[Halld-cal] BCAL sampling simulation

[semenov at jlab.org]

David:

Your list of input parameters is not quite correct:

Parameter #5: At the moment, our GEANT model of BCAL module contains 8
"effective readout" rows because of the real (2x2 cm^2) outer-cells rows
#7 and #8 are combined together; the same is for the real rows #9 and #10.
If parameterization in real individual cells is desired, the
decision/request should be made as soon as possible. (Note that the
threshold of 272 keV was applied on combined "effective" cells in the
model.)

Parameters #3 and #6: Instead of these 2 parameters, I used only one,
which is the distance between the photon hit in the module and the center
of the cell of interest.

Parameter #4: Actually, that parameterization is pretty coarse; I just
provide one set of coefficients for the events with the energy deposited
in the whole cell < 50 MeV, and another set of coefficients for the rest
of the events.

By the way, why we need to keep the coefficients in the root histograms?
What's wrong with the simple ASCII tables? (Less space in memory, works
faster etc.)

Thank you,
Andrei



> Hi Andrei,
>
>    I promised at the meeting on Tuesday to send you an e-mail indicating
> the format of the the resolution tables that I would prefer. I'm CC-ing
> the calorimetry mailing list in case anyone else would like to comment.
>
> First, let me verify what the input parameters are:
>
> 1. Total energy of incident photon that created the shower
> 2. Theta angle of the incident photon
> 3. Distance of incident photon at point of entry into BCAL from center
> of module in azimuthal direction
> 4. Energy deposited in cell (whole cell, not just fibers)
> 5. Cell row within module (1-10)
> 6. Cell column within module (1-4)
>
> I assume that depth of shower is already taken into account by index 5
> and so is not needed as separate input parameter. Let me know if this is
> not correct.
>
> Also, please remind me how the value for parameter 4. is used. Is this
> just a cut on Ecell<50MeV or Ecell>50MeV to decide which parameter set
> to use, or are there more than 2 bins in this parameter?
>
> What you will provide:
>    Effectively, a six dimensional table that has 2 values, A.) the
> sampling fraction and B.) the sampling fluctuation coefficient.
>
> I would suggest providing these in the form of a ROOT file containing a
> set of 3-dimensional (TH3F) histograms.
>   - indices x,y,z of those would correspond to input parameters 1,2,3
> listed above
>   - The names of the histograms would contain indices 4,5,6.
>      e.g.
>                SampFrac_0_50MeV_row2_col4
>                FluctuationCoeff_0_50MeV_row2_col4
>
> If my understanding is correct, this will lead to:
>   2*10*4 = 80 histograms for each of the 2 values or 160 histograms total
>
> Each histogram would be 8*12*32 = 3072 bins
>
> So for single precision, this would be about a 2MB file, not accounting
> for any compression.
>
> Please let me know if anything is incorrect or you have another idea
> regarding format.
>
> On a side note, I would like to confirm the 272keV threshold you used is
> correct. To make it clear, this is the threshold hdgeant uses to decided
> whether to write the hit for a single SiPM to the output file, or
> discard it. The 272keV comes from requiring 1MeV deposition on the far
> end which would attenuate to 272keV on the opposite end. Electronics
> thresholds are much higher, but applied later after additional effects
> (e.g. dark hits) are included.
>
> Regards,
> -David
>