[Halld-cal] MC Michel Spectra selection cuts

[Elton Smith]

Hi Andrei,

Yes, the plot is of the constants in ccdb. The most recent analysis by 
Mark has not been uploaded yet, but it differs little from what is 
already in ccdb.

Cheers, Elton.

Elton Smith
Jefferson Lab MS 12H3
12000 Jefferson Ave STE 4
Newport News, VA 23606
(757)269-7625
(757)269-6331 fax

On 10/6/15 6:46 PM, semenov at jlab.org wrote:
> Elton:
>
> The latest attenuation-length calibration that we can see in ccdb is dated
> as January 7, 2015. Does it contain the values you referred on in your
> pdf? If not, could you please provide the latest attenuation-length
> calibration data.
>
> 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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>
>