[Frost] [EXTERNAL] Re: Follow up of last FROST meeting
Michael Dugger
dugger at jlab.org
Sat Dec 28 22:43:12 EST 2019
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. 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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