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

[Chan Kim]

Hello All,

Here is a plot of momentum vs lab angle in bins of photon energies.
https://clasweb.jlab.org/rungroups/g9/wiki/images/2/2e/Low_mome_select_p_abs_theta.png

Thank you,
Chan

On Mon, Dec 23, 2019 at 3:47 PM Chan Kim <kimchanwook at gwmail.gwu.edu> wrote:

> Hello Michael,
>
> Thank you for your suggestion! I should have been more clear about the
> plots. The mmsq distribution I sent out yesterday was prior to any event
> selections.
>
> I have two quick questions..
> 1. For momentum ranges of [0.31, 0.39] GeV, the mmsq distribution (ones I
> sent yesterday) look like a gaussian distribution centered near 0, plus a
> bump at 1GeV. Are these events bad because of these bumps at 1GeV?
>
> 2. Are events with backward scattering angles not good because they don't
> have information from DC?? since the drift chamber only covers from 8deg to
> 142deg???
>
> Regards,
> Chan
>
> On Mon, Dec 23, 2019 at 3:33 PM Michael Dugger <dugger at jlab.org> wrote:
>
>> Hi,
>>
>> The last plot was for pion lab-momentum and lab-angles and the
>> center-of-mass angle definitions were also messed up :(
>>
>> I have a new plot at
>>
>> https://userweb.jlab.org/~dugger/pi0PphaseSpacePlotNew.png
>>
>> The above plot shows that the momentum values below 400 MeV ARE important
>> for MANY kinematic bins.
>>
>> However, even with the knowledge that we would be killing a bunch of bins,
>> we may have to remove events with momentum below 400 MeV due to our
>> possible inability to reconstruct the missing pi0 at low momentum.
>>
>> Sorry about any confusion my previous plot may have caused.
>>
>> Take care,
>> Michael
>>
>>
>> > Eugene,
>> >
>> > Thanks for catching that. I think I have pion angles instead of proton.
>> >
>> > I am going to back over the code to fix this.
>> >
>> > Take care,
>> > Michael
>> >
>> >> Mike,
>> >>
>> >> The vertical axis can't be right. The proton can't go backwards in the
>> >> lab
>> >> system
>> >>
>> >> -Eugene
>> >>
>> >>> -----Original Message-----
>> >>> From: Frost <frost-bounces at jlab.org> On Behalf Of Michael Dugger
>> >>> Sent: Monday, December 23, 2019 14:07
>> >>> To: Stuart Fegan <s.fegan.glasgow at gmail.com>
>> >>> Cc: frost at jlab.org
>> >>> Subject: Re: [Frost] [EXTERNAL] Re: Follow up of last FROST meeting
>> >>>
>> >>> 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
>> >>> >>>
>> >>> >>> _______________________________________________
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>> >>> >>> 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
>> >>> >
>> >>>
>> >>>
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>> >>
>> >
>> >
>> >
>>
>>
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