[Halld-cal] MC Michel Spectra selection cuts

[wmcginle at andrew.cmu.edu]

Hi Andrei,

1. I require that there is at least one 2-sided point (with a z position
from the up/down time difference) and do an energy weighted average in z
to get some average z-position for the electron z-position and apply that
averaged z-position to all 1-sided hits that are close by.

2. I require that we make at least 2 2-sided points in the electron energy
spectrum. The less than 4 module of separation cut applies to 1-sided hits
and 2-sided points. I plan to try and change this condition next week
after DNP ends though.

3. I think that the total energy deposition spectra is more useful for
calibration, but the spectra for each readout cell is interesting and
could be used as well.

Will

> 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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>
>
>