[Clas12_rgb] DVCS MC check with Mauri's new gcard

Silvia Niccolai silvia at jlab.org
Tue Oct 22 08:45:59 EDT 2019


Hi Stepan,
here are some numbers, the ones I can get out with my current analysis 
code (I have epX but I don't have the enX case):
1) Ratio of epgamma/epX events: 14.296% for NOSHIELD, 14,17% for SHIELD
2) Ratio of epgamma/generated: 3.293% for NOSHIELD, 3.256% for SHIELD
3) Ratio of engamma/generated: 1.146% for NOSHIELD, 1.136% for SHIELD
4) Ratio of epX/generated: 23.04% for NOSHIELD, 22.97% for SHIELD
It seems like there is a very very very small loss of events (~0.01% -
0.1%) in the SHIELD case, basically negligeable.
Best regards,
Silvia




On Tue, 22 Oct 2019, Stepan Stepanyan wrote:

> Silvia,
>
> One thing to compare is the fraction of ep\gamma events per detected ep (or similarly the fraction of en\gamm per detected en pair). The only effect that the new scattering chamber may have is a bit more material in front of photons going to FT.
>
> Stepan
>
>> On Oct 22, 2019, at 5:08 AM, Silvia Niccolai <silvia at jlab.org> wrote:
>>
>> Hello all,
>> following our discussion of last week, I have run pDVCS and nDVCS full simulations, and compared the outputs obtained with the standard RGB gcard and with the new one that Mauri sent us, containing his new rohacell scattering chamber.
>> I generated roughly the same number of events for the two sets of simulations. The results are in the attached figures: noshield is the standard gcard, shield is with the new rohacell piece.
>> I am plotting rec-gen quantities. In each of the three columns are p, theta, phi, while the lines are: electron, proton, photon, and neutron.
>> You can try to play spot the differences, but to me it all looks pretty equal.
>> So, I'd conclude that from the DVCS point of view the new scattering chamber has no negative impact.
>> I didn't check with interactive gemc to make sure that the new geometry was correctly implemented, but from the gemc log of my jobs it seems like it correctly imported the "e" variations for the target.
>> From my point of view, therefore:
>> - if this new scattering chamber reduces the DC occupancies and thus improves ttracking efficiency, as Maurizio showed last week;
>> - if its construction and installation won't affect our schedule;
>> - if the other experiments' spokespeople agree I'd say we can go ahead and use it.
>> Best regards,
>> Silvia
>>
>> <res_noshield.jpg><res_shield.jpg>_______________________________________________
>> Clas12_rgb mailing list
>> Clas12_rgb at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/clas12_rgb
>
>


More information about the Clas12_rgb mailing list