[Frost] [EXTERNAL] Re: Follow up of last FROST meeting

[Michael Dugger]

Hi,

Chan is just trying to answer questions raised about a possible momentum
cut. I suggested that he look at where his events are in terms of
kinematic bins he will report on. My idea was to see if pushing up the
momentum cut to perhaps 400 MeV would cause any issues within his
kinematic binning.

I just made a plot that can be found at

https://userweb.jlab.org/~dugger/pi0PphaseSpacePlot.png

that shows the lab angle versus lab momentum for protons coming from the
reaction gamma p -> p pi0. The black curves are for constant photon energy
and the blue curves are for constant proton center-of-mass cosine values.

The above plot would have to be verified but it looks like there is no
need to worry about low momentum protons.

The idea I had was for Chan to produce this type of information using real
data, but I did a poor job of explaining what I meant.

I was trying to make life easier, but perhaps did not accomplish that :(

Take care,
Michael

> Hi Chan,
>
> I'm going to chuck my two cents in, and reply to the FROST list, because
> I missed the meeting last week.  Given the pion is reconstructed from
> the proton missing mass, what's the motivation for looking at proton
> momenta below the threshold where it can reliably reconstructed in CLAS
> as a proton?  Is this to tune the cut, perform systematic studies, or is
> there a physics motivation here that I'm missing?
>
> Cheers,
>
> Stuart
>
> On 23/12/2019 11:47, Michael Dugger wrote:
>> Chan,
>>
>> It is a bit of a data dump.
>>
>> What is your binning going to by for the analysis? Are you really going
>> to
>> report values for E_gamma near 400 MeV?
>>
>> On slide 3 you show MM^2 and state that MM^2 for p < 280 MeV/c don't
>> look
>> like the others. I'm not convinced that you can say much about the MM^2
>> shown above p = 280 MeV/c.
>>
>> For your previous presentation:
>>
>> https://clasweb.jlab.org/rungroups/g9/wiki/images/9/94/FROST_2019_12_18.pdf
>>
>> on slide 2 you had a nice fit to the MM^2 distribution where you pulled
>> off a pi0 mass. Are you able to do that for the low momentum? Is it
>> possible that you can not pull out any pi0 from the low momentum data? I
>> just do not see any pi0. Am I missing something?
>>
>> Take care,
>> Michael
>>
>>>
>>>
>>> Dear FROST run group,
>>>
>>> Hello, below is a link to my slides for follow up of last FROST
>>> meeting(12/19):
>>> https://clasweb.jlab.org/rungroups/g9/wiki/images/e/ed/FROST_2019_12_22.pdf
>>>
>>> 1. Distributions of kinematics (MMSQ, dt, d\beta) for particles in
>>> lower
>>> momentum ranges are plotted to see whether lower momentum particles are
>>> of
>>> any use for my asymmetry calculation.
>>>
>>> 2. Proton selection, using beta difference, was revised to a simpler
>>> version where static cuts on beta diff are applied at +/- 0.06
>>>
>>>
>>> Thank you,
>>> Chan
>>>
>>> _______________________________________________
>>> Frost mailing list
>>> Frost at jlab.org
>>> https://mailman.jlab.org/mailman/listinfo/frost
>>>
>>
>> _______________________________________________
>> Frost mailing list
>> Frost at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/frost
>
> --
> Dr Stuart Fegan
> Honorary Research Associate
> Nuclear Physics Group
> University of Glasgow
> (Currently at the University of York)
>
> E-mail: s.fegan.glasgow at gmail.com
>
> _______________________________________________
> Frost mailing list
> Frost at jlab.org
> https://mailman.jlab.org/mailman/listinfo/frost
>