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

Sun Dec 29 21:27:00 EST 2019

Hello Michael,

The results on target separation did not use bayesian weighting. I was
developing the bayesian version, but I stopped.
Below link is a comparison of the mmsq from the "true" butanol region and
"ML classified" butanol region [2, 6]cm.
https://clasweb.jlab.org/rungroups/g9/wiki/images/7/7c/ML_TS_mmsq_buta_half_vs_half.png

Thank you,
Chan

On Sun, Dec 29, 2019 at 11:00 AM Michael Dugger <dugger at jlab.org> wrote:

> Chan,
>
> Did you use bayesian weighting on the vertex distribution?
>
> Within the z-vertex overlap region, there is no way to distinguish between
> the carbon and butanol. This is a physics statement and trumps all of the
> machine learning language. It is simply not possible to faithfully sort
> carbon and butanol events within the z-vertex overlap region (four-vectors
> of momentum and position overlap).
>
> For the machine learning part of your dissertation, you should concentrate
> on problems better suited to machine learning. In particular, you should
> choose something that is separable. It makes no sense to try and separate
> something that cannot be separated.
>
> The mixing of bayesian and neural net should be much more flexible, but
> you have to be careful to show everything as a probability.
>
> Take care,
> Michael
>
>
> > Thank you for your comments!! I will make the mmsq comparison plot of the
> > first half and second half of the butanol target.
> >
> > Yes, there is a lot of ambiguity in ML approach and until I find a way to
> > probe into how the training is actually done in neural nets, it is still
> a
> > black box that I should not trust.
> > My first aim is to correctly produce the results following the simplest
> > approaches without any techniques that has unknown errors. Only reason
> why
> > I used machine learning is because my dissertation proposal includes the
> > use of machine learning (or at least try) and my graduate committee
> > approved on it.
> >
> > I think there are many obstacles in regards to ML even before trying to
> > determine whether results from ML is usable or not. First I need to be
> > able
> > to know how the training is done and the reasoning behind the
> > classification if I am to use the result.
> > To do so, I need to have a visualization of how weights are being changed
> > as they are being passed on to each neural layers and how they are being
> > optimized. Secondly, I need to find a way to compute the uncertainty in
> > training. I was trying to build a kind of neural net, called bayesian
> > neural network which passes probability density distribution instead of
> > scale weights as shown in below figure. Then use the final uncertainties.
> >
> > Bottom line is, I will not focus on ML until my standard procedures are
> > approved and my results on asymmetry E are reasonable.
> >
> > [image: BayesianNN.png]
> >
> >
> > Thank you,
> > Chan
> >
> >
> >
> >
> > On Sat, Dec 28, 2019 at 10:43 PM Michael Dugger <dugger at jlab.org> wrote:
> >
> >>
> >> Hi,
> >>
> >> Sounds like a lot of work for little gain. Arguing that the shapes are
> >> correct will require more effort than it will be worth, and comparing
> >> front to back is not as straight-forward as it might seem (differing
> >> amounts of eloss correction and acceptance at low momentum and low
> >> angle).
> >>
> >> If that is how Chan wants to use his time, I will not stand in his way.
> >>
> >> Take care,
> >> Michael
> >>
> >> > Then in that case it should show up in different dilution factor for
> >> the
> >> > first half of the target as compared to the second half. This should
> >> be
> >> > rather straightforward to show.
> >> >
> >> > If one can argue that the shapes are correct (vertex resolution) one
> >> can
> >> > use these to tailor the z vertex cuts on a bin by bin basis.
> >> >
> >> > Sent from my iPhone
> >> >
> >> >> On 29 Dec 2019, at 02:47, Michael Dugger <dugger at jlab.org> wrote:
> >> >>
> >> >> Hi,
> >> >>
> >> >> The same problem applies for the separation of carbon from butanol.
> >> >> There
> >> >> is no way to distinguish the two types of bound content. The neural
> >> net
> >> >> is
> >> >> making some sort of distinction that, on the face of it, looks
> >> >> reasonably
> >> >> good. It looks like there are two gaussian distributions that
> >> overlap.
> >> >> The
> >> >> problem is that there is no reason to believe that the separation is
> >> in
> >> >> any way faithful. Part of the carbon tail in the overlap region is
> >> >> actually some combination of carbon and butanol and part of the
> >> butanol
> >> >> tail in the overlap region is actually some combination of carbon and
> >> >> butanol. We just do not know the relative amounts. Perhaps the shapes
> >> >> are
> >> >> somewhat correct and we could make a good guess as to the proportion
> >> of
> >> >> each type of events in the overlap?
> >> >>
> >> >> In short, the separation looks nice but can not be used as
> >> representing
> >> >> pure samples of carbon (or butanol) in the overlap region.
> >> >>
> >> >> Take care,
> >> >> Michael
> >> >>
> >> >>> I agree that the classification of free vs bound protons is not
> >> >>> possible.
> >> >>> What the plot he sent shows (maybe thats just me misreading it) is
> >> the
> >> >>> classification of events based on target: i.e. butanol vs carbon. If
> >> >>> the
> >> >>> ML can correctly classify butanol vs carbon events then a vertex cut
> >> is
> >> >>> not really essential. If he can show that the dilution (ratio of
> >> bound
> >> >>> to
> >> >>> total) is the same between events classified as butanol and events
> >> with
> >> >>> tight z vertex cuts, that is a first indication that the
> >> classification
> >> >>> is
> >> >>> adequate.
> >> >>>
> >> >>> I might not be following the discussion or have miss-interpreted
> >> >>> things:
> >> >>> its 2am here afterall :)
> >> >>>
> >> >>> Sent from my iPhone
> >> >>>
> >> >>>>> On 29 Dec 2019, at 00:55, Michael Dugger <dugger at jlab.org> wrote:
> >> >>>>
> >> >>>> Hi,
> >> >>>>
> >> >>>> My impression of the machine learning implemented by Chan was that
> >> it
> >> >>>> was
> >> >>>> not able to separate the ice from the carbon.
> >> >>>>
> >> >>>> The problem is that there is no way to take an event originating
> >> from
> >> >>>> a
> >> >>>> free proton (like that in ice) and distinguish that event from one
> >> >>>> that
> >> >>>> originates from a bound proton (like that in carbon). Because of
> >> this,
> >> >>>> the
> >> >>>> two types of events are NOT linearly separable.
> >> >>>>
> >> >>>> Look at it this way: If Chan could remove the signal coming from
> >> ice
> >> >>>> from
> >> >>>> that of carbon, why not just classify the free proton directly from
> >> >>>> the
> >> >>>> bound content within butanol?
> >> >>>>
> >> >>>> If machine learning could distinguish free proton from bound, there
> >> >>>> would
> >> >>>> be no need for a carbon subtraction we would just use machine
> >> learning
> >> >>>> to
> >> >>>> do the separation.
> >> >>>>
> >> >>>> In the MM-Sq region that is physical, the protons from bound and
> >> >>>> unbound
> >> >>>> have angles and momentum that overlap and can not be distinguished
> >> >>>> from
> >> >>>> one another.
> >> >>>>
> >> >>>> Take care,
> >> >>>> Michael
> >> >>>>
> >> >>>>> Hi Chan,
> >> >>>>>
> >> >>>>> I dont know the details of your classification, but my first
> >> >>>>> impression
> >> >>>>> is
> >> >>>>> yes. If you have a reliable classification then you can (in
> >> >>>>> principle)
> >> >>>>> not
> >> >>>>> apply z vertex cuts. You can just use your butanol events as
> >> chosen
> >> >>>>> by
> >> >>>>> the
> >> >>>>> classification And your carbon events for establishing the bound
> >> >>>>> nucleon
> >> >>>>> contributions. This would of course need to be studied in a
> >> >>>>> systematic
> >> >>>>> way
> >> >>>>> and a classification uncertainty needs to be established. It looks
> >> >>>>> like
> >> >>>>> you were also able to remove the ice build up downstream the
> >> carbon
> >> >>>>> target. Might be good to see the missing masses originating from
> >> the
> >> >>>>> two
> >> >>>>> targets. A quick check for your classification would be to plot
> >> the
> >> >>>>> missing mass of events coming with z vertex that selects the first
> >> >>>>> half
> >> >>>>> of
> >> >>>>> your target (any events away from the carbon target ). Then scale
> >> >>>>> this
> >> >>>>> and
> >> >>>>> see if you can get the missing mass distribution to match the one
> >> >>>>> from
> >> >>>>> your classified butanol events. If it does, it means you are
> >> >>>>> correctly
> >> >>>>> removing any contributions from the carbon target which would only
> >> >>>>> contribute to background. If you fail to match the free proton
> >> peak
> >> >>>>> and
> >> >>>>> the bound nucleon contributions it means that the classification
> >> >>>>> might
> >> >>>>> need some work.
> >> >>>>>
> >> >>>>> Sent from my iPhone
> >> >>>>>
> >> >>>>>>> On 28 Dec 2019, at 21:26, Chan Kim <kimchanwook at gwmail.gwu.edu>
> >> >>>>>>> wrote:
> >> >>>>>>
> >> >>>>>> 
> >> >>>>>> 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.Ã‚  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?Ã‚  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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