[d2n-analysis-talk] Cerenkov Detector Plane and Beta

[Lamiaa El Fassi]

 Hi Dave,

 I talked to Chiranjib about the beta cut for the electrons identification.
 He said that there is no need to apply such cut to select the electrons
 sample since the time resolution of the S1 plane is two times worse
 than the S2m plane.

 In his analysis, he used the RF timing to calibrate the S2m plane.
 The obtained resolution was ~ 500 ps. But the time resolution of S1
 plane was ~ 1ns, which is not so good to be required for any particle's
 identification.

 In fact, I don't know what is the reason behind your beta cut requirement.
 A good electrons sample can be selected by combining the Cerenkov
 and the pion rejector signals. Of course the timing information is
implicitly
 included to extrapolate the track from the vertex; the interaction point in
the
 target plane, through different LHRS detectors. For that reason an adequate

 scintillators calibration is necessary to extract the particle's time of
flight.

 As for your beta distribution plot, I can't understand why the main peak is

 not centered around 1. This shift can be related to the time calibration of
the
 scintillators planes. Have you done this calibration or not yet?

 Best regards,

 Lamiaa

 PS: Since I forgot to change my gmail address to the JLab one, I got a
notification
 email that my message is waiting for the moderator approval. So, I canceled
the last
 posting to this mailing list. I apologize for the people who my receive
this email twice.


>
> On Wed, Oct 28, 2009 at 12:26 PM, David Flay <flay at jlab.org> wrote:
>
>> Hey Brad,
>>
>> To follow up from last meeting our discussion about the effect of a cut on
>> either the Cerenkov ADC or beta as seen in the Cerenkov Detector plane,
>> I've assembled some plots.
>>
>> The first is the the detector plane (L.cer.trx:L.cer.try) with some
>> 'standard cuts' (= evtypebits cut for T3, one-track, VDC).
>>
>> The second is the standard ones plus a cut on the Cerenkov sum (greater
>> than 600 channels) -- no change in the distribution; so that wasn't the
>> issue.
>>
>> The third is the previous two cuts, plus a cut on the main peak of beta
>> (see last plot for a plot of beta) -- there's a preference for the events
>> to fill the lower portion of the plot here.  Considering that beta is
>> constructed based off the timing between the S1 and S2 planes, maybe the
>> underlying issue is in the Scintillators?
>>
>>
>>
>> -------------------------------------------------
>> David Flay
>> Physics Department
>> Temple University
>> Philadelphia, PA 19122
>>
>> office: Barton Hall, BA319
>> phone: (215) 204-1331
>>
>> e-mail: flay at jlab.org
>>        david.flay at temple.edu
>>
>> website: http://www.jlab.org/~flay <http://www.jlab.org/%7Eflay>
>> -------------------------------------------------
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>>
>
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