[Primexd] [Revised Logentry] Accidentals in tagger, Be target

[Alexander Somov]

Hi Ashot,

The fraction of accidentals depends on the reconstruction
channel (energy resolutions, etc.) and how you do physics
analysis (whether you perform kinematic fitting or simply
subtract accidentals, etc).

Using the PS trigger and high-granularity counters,
implies that you reconstruct energy of the event
with the great precision (therefore you can study the fraction
of accidentals as a function of energy resolution).

I doubt that we can do detailed reconstruction studies
of Compton and di-photons during this beam period. Running
at 200 nA is (probably) Ok.

Another thing to consider, is the fraction of accidentals
in the CCAL .


Cheers,
       Sasha



On 03/25/2019 10:43 PM, gasparan at jlab.org wrote:
>    Sasha,
>   Though it may not be much different but, it would be better to use
>   our experimental trigger instead of the PS trigger.
>
>   Thanks,
>   Ashot
>
>> Logentry Text:
>> --
>> Some quick (rough) estimates of the fraction of accidental hits in the
>> tagger (denoted as bg/sig in Fig. 2).
>>
>> 1. Consider PS trigger. Search for hits in the tagger around the PS energy
>> in the window +- 1 GeV
>>
>> 2. Count number of hits correlated with the trigger time (signal).
>> Determine accidentals
>> from the side band of the time distribution (see Fig. 1). Subtract
>> accidentals
>>
>> 3. Fig. 2: fraction of accidental hits (in a  +- 1 GeV energy window) in
>> the tagger as a function of the tagger energy
>>
>> I'll  check it later, just scratched the surface now.
>>
>>
>>
>> ---
>>
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>> https://logbooks.jlab.org/entry/3672169_______________________________________________
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>