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

[Chan Kim]

Thank you for your replies.

@Michael,
For the z-vertex plot, only p<300MeV particles are removed. I will change
the momentum selection region and see how z-vertex resolution changes as
soon as I have other steps finished. I kept them for now, so I can compare
my asymmetry with and without particles with p=[300, 400] MeV.

@Nick,
In regards to free polarized proton contributions in carbon vertex (left
tail of the carbon distribution), would it be ok to use classification
results from machine learning? Below is a plot of separation of butanol and
carbon in small angles.
https://clasweb.jlab.org/rungroups/g9/wiki/images/0/06/Zvrt_1bin_angle.png

Thank you,
Chan


On Sat, Dec 28, 2019 at 12:42 PM Nicholas Zachariou <nickzachariou at gmail.com>
wrote:

> Dear Chan,
>
> I have done several studies on this that should be documented in my
> analysis note. As Michael said, the difficulty lies in the determination of
> the dilution factor. If you are using carbon data to determine this, then
> you need to make sure you account correctly for free polarised proton
> contributions within your carbon vertex cut that actually comes from
> butanol events (this is different than the ice built up). If you are using
> parametrization of the bound nucleon contributions then the dilution is
> more straightforward, but you would need to think/study free unpolarised
> proton contributions to butanol events from the ice built up downstream
> your carbon target. This can been done by varying the butanol z vertex cut
> andcomparing your determined observable. There are several ways you can do
> this and we can chat more if needed.
>
> Best regard,
> Nick
>
> Sent from my iPhone
>
> > On 28 Dec 2019, at 16:23, Michael Dugger <dugger at jlab.org> wrote:
> >
> > Chan,
> >
> > The variables that are important are polar angle and momentum of the
> > identified particle. Did you keep the low momentum protons?
> >
> > When it comes to choosing the range of vertex selection for each target,
> > the method you use for removing the bound nucleon content might be a
> > factor. From the plots you created, you can see the difficulty that you
> > face at low angle.
> >
> > At low polar angle you have the case that there very well could be some
> > leakage of carbon vertices in your butanol definition. This could cause
> > dilution factors to be messed up.
> >
> > I would cautiously move forward concentrating on the bins that look good.
> > Once everything was running well for the "good" stuff, I would start
> > trying to fix the more difficult bins.
> >
> > Take care,
> > Michael
> >
> >> Hello Michael,
> >>
> >> The pi0 mass shifting from 125MeV (slide 2) to 134MeV (slide 6) happened
> >> simply due to a change in number of bins. On slide 6, I tried to have
> the
> >> same binning for both ELOSS and ELOSS+momentum correction
> >> distributions,causing inaccurate peak locations. After momentum
> >> correction,
> >> the mmsq distribution has much sharper peaks. So, 125MeV is the correct
> >> value of mmsq after ELOSS distribution, but for ELOSS + momentum
> >> correction, I will redo the calculation. Sorry for the confusion.
> >>
> >> I have another question regarding the z-vertex resolution in angles.
> Below
> >> is a plot that Eugene suggested to make (Z-vertex position in bins of
> >> photon energies and angle bins).
> >>
> https://clasweb.jlab.org/rungroups/g9/wiki/images/a/ac/Zvrt_select_lab.png
> >>
> >> As you can see, the z-vertex resolution is very poor in small scattering
> >> angles, unable to clearly distinguish the butanol and carbon region. do
> >> you
> >> have any suggestions in choosing the selection ranges for small
> angles..?
> >>
> >> Thank you,
> >> Chan
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >>> On Thu, Dec 26, 2019 at 4:53 PM Michael Dugger <dugger at jlab.org>
> wrote:
> >>>
> >>> Chan,
> >>>
> >>> It is probably a good idea to try and keep the low momentum events, but
> >>> I
> >>> would start out by removing them. Once you feel like you have
> everything
> >>> else under control, then you add in the p < 400 MeV/c events.
> >>>
> >>> You can see if the momentum cut makes the pi0 mass closer to the
> nominal
> >>> value. Essentially, you just recreate slides 2 and 6 from your December
> >>> 18
> >>> update:
> >>>
> >>>
> https://clasweb.jlab.org/rungroups/g9/wiki/images/9/94/FROST_2019_12_18.pdf
> >>>
> >>> Note: On slide 2 you have pre-ELOSS mass of pi0 = 196 MeV and
> post-ELOSS
> >>> mass of pi0 = 125 MeV. BUT on slide 6 you have post-ELOSS mass of pi0 =
> >>> 134 MeV!! How did that happen? Then after ELOSS + momentum correction
> >>> the
> >>> pi0 mass = 89 MeV. You want to get that all straightened out with the p
> >>>>
> >>> 400 MeV/c events. You mass of the pi0 after the ELOSS and momentum
> >>> corrections should be the correct value. The momentum correction is
> >>> designed to bring the pi0 mass to the correct value.
> >>>
> >>> Take care,
> >>> Michael
> >>>
> >>>> Hello Michael,
> >>>>
> >>>> Yes, I now understand what you are saying about the momentum
> >>> acceptance
> >>>> varying rapidly between 300 and 400 MeV around scattering angle of
> >>> 35deg.
> >>>>
> >>>> Would it be a bad idea to apply different low momentum cuts for
> >>> particles
> >>>> under 35deg and above 35deg? So, 400MeV for particles with angle <
> >>> 35deg
> >>>> and 300MeV for particles with angle >35deg.
> >>>> Because for higher energy photon events (photon energy > 1 GeV), it
> >>> looks
> >>>> like there are lots of events in p = [350, 400] MeV region.
> >>>>
> >>>> Thank you,
> >>>> Chan
> >>>>
> >>>>
> >>>> On Tue, Dec 24, 2019 at 3:50 AM Michael Dugger <dugger at jlab.org>
> >>> wrote:
> >>>>
> >>>>> Chan,
> >>>>>
> >>>>> For these sorts of plots it is interesting to make an additional MM^2
> >>>>> cut.
> >>>>> If you make a missing mass cut near the mass of the pion, you
> >>> restrict
> >>>>> the
> >>>>> events to have the kinematics of
> >>>>>
> >>>>> gamma p -> p pi0 .
> >>>>>
> >>>>> As it currently stands, you are showing the theta versus momentum
> >>>>> distribution for all possible reactions. This is not a bad thing and
> >>> the
> >>>>> plots have interesting features.
> >>>>>
> >>>>> The depletion stripes are probably bad time-of-flight paddles. You
> >>> can
> >>>>> see
> >>>>> from the depletion stripes how the magnetic field is bending the path
> >>> of
> >>>>> the charged particles as a function of momentum.
> >>>>>
> >>>>> The enhancement stripes are probably from the reaction gamma p -> p
> >>> pi0
> >>>>> (compare to
> >>> https://userweb.jlab.org/~dugger/pi0PphaseSpacePlotNew.png
> >>>>> ).
> >>>>>
> >>>>> You can clearly see the acceptance in polar angle and momentum. For
> >>>>> angle
> >>>>> above 35 degrees, it looks like the momentum acceptance is rapidly
> >>>>> changing between 300 and 400 MeV/c. This is probably the clearest
> >>>>> evidence
> >>>>> that a cut at 400 MeV/c is appropriate. For angles below ~35 degrees
> >>> the
> >>>>> momentum acceptance issue is being caused by a bad time-of-flight
> >>>>> paddle.
> >>>>>
> >>>>> Take care,
> >>>>> Michael
> >>>>>
> >>>>>> 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
> >>>>>>>>>>>>>>
> >>>>>>>>>>>>>> _______________________________________________
> >>>>>>>>>>>>>> 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
> >>>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>>
> >>>>>>>>>>> _______________________________________________
> >>>>>>>>>>> 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
> >>>>>>>>
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>>>> _______________________________________________
> >>>>> 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
>
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