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

Michael Dugger dugger at jlab.org
Sun Dec 29 23:27:28 EST 2019 

Chan,

I do not know what I am supposed to think about the plots. What am I
supposed to learn? The shapes for the "true" and "ML classified" are
different. Shouldn't the shapes be the same?

Also, what does "Carbon ML [2,6]cm" mean and how is it different from the
"Butanol ML [2,6]cm" ?

I honestly do not know what you want to do with the machine learning. I
think it would be very good to have a clear goal of classifying something
that is separable and then make a plan on how to move forward. Perhaps you
have a good idea as to where you are going and just need to communicate
that better. I just do not know.

I wish I could be of some help.

Take care,
Michael

> 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.Â
>> 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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