[Halld-cal] MC Michel Spectra selection cuts

[semenov at jlab.org]

Elton and Will:

I need a few clarifications:

1. How you reconstruct the energy in the cell for 1-sided case?

2. About the condition to have at least 2 but less than 4 modules with
energy depositions: Do you count 1-sided energy depositions here?

3. Do you need the spectra for each readout cell or you need the spectra
for the total energy deposition (above threshold) in the BCAL?

Thank you,
Andrei

>
> Hi Andrei,
>
> Following our discussion at the reconstruction meeting yesterday, it
> would be nice to be able for Will to compare his electron spectra with
> the Michel generated MC.
>
> Thresholds: The flash threshold is 5 counts above threshold. This
> corresponds to an attenuated energy of Th0=2.3 MeV using the following
> constants:
> Th0 = 5 peak counts * 15 int cts/peak * 0.03 MeV/int count
> Due to attenuation lambda, the threshold is in fact higher depending on
> the position of the hit, i.e.
> Energy Thresh (z) > Th0 x exp [(L/2 + z)/lambda]; upstream
> Energy Thresh (z) > Th0 x exp [(L/2 - z)/lambda]; downstream
> where z is measured relative to the center of the module and increases
> downstream. For the attenuation length you can check what is currently
> in ccdb. See for example
> https://logbooks.jlab.org/files/2015/09/3352084/ccdb_get_attenuation_parameters_col0.pdf
> You can either use an average or a range based on the measured
> distribution.
>
> It would be nice to see the spectra by varying the threshold Th between
> 0.5xTh0 and 2xTh0.
>
> You also mentioned that we might consider including selection cuts,
> which Will is using in his analysis. He uses the following selection cuts:
> 1. late time hit cut
> 2. requirement that energy is deposited in at least 2 channels
> 3. the electron energy is deposited in less than 4 modules
> 4. at least one point object is in the distribution.
>
> Cuts 1 and 3 should all be satisfied by bona fide events, so no need to
> add to MC.
> Cut 2 will likely be relaxed as the analysis evolves, so no need to add
> at this time.
>
> The only cut, which should be included, is #4. This requires that at at
> least one cell have a hit on both ends, i.e. the threshold requirement
> (above) be satisfied for at least one cell for both upstream and
> downstream hits.
>
>
> Send questions or clarifications to me or Will.
>
>
> Thanks, Elton.
>
>
> Elton Smith
> Jefferson Lab MS 12H3
> 12000 Jefferson Ave STE 4
> Newport News, VA 23606
> (757)269-7625
> (757)269-6331 fax
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