[Frost] tagger sag

[dugger at jlab.org]

Sungkyun,

I used 25 MeV wide bins.

I am using the terms "photon energy correction" and "tagger sag
correction" to mean the same thing. It is probably best to call it a
photon energy correction, but then you must determine why we would need
such a correction. The "tagger sag correction" has a well understood
physical origin.

The biggest problem with this sort of study is that we are working in the
0.1% level. It is not easy to be sure that what you are seeing is a "true"
correction, or some other systematic that is "popping up". If you start to
see a three bump structure, then you know that you are seeing the tagger
sag. Otherwise, you are probably just seeing some problem with the
approximation you are using. This is not an easy thing to measure. Either
you should see a three bump structure when you use the 2.4 GeV set (almost
all of the first bump will be missing from the 1.6 GeV set), OR you should
see the correction be zero to within about 0.1% for all photon energy
bins.

Also, since there is probably a tagger sag correction already applied to
the data, the three bump structure might not look the same as g1c. The g8b
tagger sag correction was always positive and the bumps were more
pronounced than the g1c correction. The g8b data was supposed to have the
tagger-sag corrected in the cooking stage, but either was not applied, or
it was not quite right. We don't know.

I did not assume that the photon energy correction was put into your code.
I just thought that it might improve your photon pulls once correction
factors were put in the kinematic fitter. Once the kinematic fitter has
all of the pulls looking good for CH2, we know that the energy and
momentum corrections are good.

Take care,
Michael

> Michael,
> I think there is misunderstanding now.
> Do you mean photon energy correction is tagger sag correction? and do
you
> think I already apply it in my code? If so, it is wrong.
> The only correction I have used now is eloss correction. and I found
some
> mistake in my old code.
>   histograms before correcting my mistakes
>   http://www.jlab.org/Hall-B/secure/g9/sungkyun/6-14-10.html
>   histograms after correcting my mistakes
>   http://hadron.physics.fsu.edu/~skpark/research/research_jun1410.html
> After applying eloss correction, the value, [E(cal. photon) - E(mea.
photon)]/[E(mea. photon)] has improved more. My current result is eloss
correction make FROST data improved.  After applying photon energy
correction in my code, I will compare before results to after. It is also
> interesting.
> It is good idea that the correction factors should be considered first
from CH2. That will be my first motivation to research the momentum
correction for FROST.
> I will also talk with Chuck to decide the best binning for momentum
correction.
> You said my binning is not as fine as what you have used in the past. My
current binning of the photon energy is 20 MeV and when I used a
fitting,
> I have combined 5 bins to get more points in the fit. what was your
binning of the photon energy?  In the next work, I will use more
statistics.
> It is also good point to use the data set of the 2.478 GeV.
> Best wishes
> Sungkyun Park
> Florida State University
>> Sungkyun,
>> The plots are looking better. Good job.
>> For the CH2 target you are seeing photon energy corrections from ~ zero
to
>> 0.4%. Mike Williams saw a photon energy correction for g1c from about
-1.0% to 0.2%. When Mike Williams made these corrections, his pulls for
the photon energy became much better.
>> You might want to see if the photon energy correction you have
>> calculated
>> helps with your photon pulls.
>> You are in much better position to determine the best binning to use
for
>> determination of the momentum corrections. You might want to
>> consult with
>> Chuck. He probably has a good feel for what is reasonable.
>> One thing to keep in mind: Your best determination of the energy and
CLAS momentum corrections will come from the CH2 target. It is not even
worth your time to make any decisions regarding these correction
factors
>> from the much more complicated Butanol case (or the Carbon that is
contaminated with Butanol). The correction factors should only come from
>> CH2. Making any decision regarding the correction factors based on
Butanol
>> is a very bad idea.
>> Once the photon energy and CLAS momentum correction factors are
determined
>> from CH2 and are shown to give good pull distributions, we can
>> worry about
>> why we are having problems with the Butanol target.
>> Take care,
>> Michael
>> On Wed, 16 Jun 2010, Sungkyun Park wrote:
>> > Michael,
>> >
>> >   I find some mistakes in my last updated plots. When I project
>> histograms, I used the wrong plots.
>> >   I make the same histograms like before again after correcting
>> my mistakes:
>> >
>> http://hadron.physics.fsu.edu/~skpark/research/research_jun1410.html>
>> >  I also start to look the momentum correction for FROST.
>> >  We can share some idea together. To do this, we need to fix the
>> bins range.
>> >
>> >  I mean g8b used the definition of the following bins.
>> >
>> > proton
>> >
>> >    * ? 1 - 7, 10 degrees each bin
>> >    * ? 1 - 18, 20 degrees each bin
>> >    * momentum
>> >      mom01 = [0.2 - 0.45], mom02 = [0.45 - 0.7], mom03=[0.7 -
>> 0.95], mom04=[0.95 - 1.2], mom05=[1.2 -1.45], mom06=[1.45 -  ]
>> >
>> >  pion
>> >
>> >    * ? 1 - 14, 10 degrees each bin
>> >    * ? 1 - 18, 20 degrees each bin
>> >    * momentum
>> >       mom01=[0.05 - 0.3],mom02=[0.3 - 0.55],mom03=[	0.55 -
>> 0.8],mom04=[0.8 - 1.05],mom05=[1.05 - 1.3],mom06=[1.3 -
>> 1.55],mom07=[1.55 - 1.80],mom08=[1.80 -  ]
>> >
>> > we need to decide to use the same bin distribution of g8b or
>> another group or make our bins.
>> > I have one suggestion about the bin distribution for FROST
>> >
>> >
>> http://hadron.physics.fsu.edu/~skpark/research/research_jun1510.html>
>> > Let me know your idea.
>> >
>> > Best wishes
>> > Sungkyun Park
>> > Florida State University
>> >
>> > ----- Original Message -----
>> > From: dugger at jlab.org
>> > Date: Monday, June 14, 2010 10:39 pm
>> > Subject: Re: [Frost] tagger sag
>> > To: Sungkyun Park <sp06k at fsu.edu>
>> > Cc: dugger at jlab.org, frost at jlab.org
>> >
>> >> Sungkyun,
>> >>
>> >> I am sorry.
>> >>
>> >> I did not understand what was shown.
>> >>
>> >> At first glance, it looks like the tagger sag is correctly dealt
with. The
>> >> error bars are still a bit large. If I read your CH2 (eloss
>> corrected)>> plot correctly, it looks like the energies are within +/-
0.5%.
>> >> There is
>> >> not enough photon energy bins to see if there is the 3 bump
>> structure.>>
>> >> If we assume that the tagger sag has been dealt with, then the next
thingis to find the momentum corrections.
>> >>
>> >> I got an email from Brian Vernarsky today. He stated that he is
ready to
>> >> start looking at the energy and momentum corrections for g9. He has
hiscode working for g1c. With any luck we should get some
>> >> correction factors
>> >> for g9 soon.
>> >>
>> >> I apologize for the confusion.
>> >>
>> >> Sincerely,
>> >> Michael
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>> Hi Michael,
>> >>>
>> >>>> Unless the photon pulls are better than you have previously
>> >> reported, the
>> >>>> energy differences shown can not be taken as accurate. This
>> >> means that
>> >> I  do not know what to say regarding your most recent plots.
>> >>>
>> >>> I do not understand why you say about the photon pull with my
>> >> yesterday's
>> >>> plots.
>> >>> I do not use any kinematic fitting term in my yesterday's plots.
>> >> I only
>> >> follow your suggestion to check if the tagger sag is correctly
includedin g9a.
>> >>> Thus, I make histograms with [E_calculated -
>> >> E_measured]/E_measured and
>> >> enough statistics to get
>> >>> the numbers to the 0.1 % level.
>> >>>
>> >>> My understanding is that the kinematic fitter need to have
>> >> momentum as
>> >> the
>> >>> initial value and it correct momentum using energy conservation.
>> >> In this
>> >> case, the initial energy is very important factor.
>> >>>
>> >>> Before kinematic fitting, the momentum can be corrected by using
>> >> severalcorrection. now I used eloss correction and will use
>> >> momentum correction
>> >> for g9a.
>> >>>
>> >>> Unfortunately, after applying the eloss correction, the pull
>> >> distribution
>> >>> in butanol target is still very bad.
>> >>> I am not sure if our eloss package correct momentum and to
>> check the
>> >> effect of our eloss package, I make the plot with the ratio of the
calculated photon E to measured photon E.
>> >>>
>> >>> If in my yesterday' plot, we can not check the problem of the
>> tagger>> sag,
>> >>> what do I make to check them?
>> >>> It is also important to check if we have the problem of the
>> >> tagger sag now.
>> >>> I think in the current status, we can not use the result of the
>> >> kinematic
>> >>> fitting.
>> >>>
>> >>> How do you think that I add the code to correct the tagger sag
>> >> from g8b
>> >> in
>> >>> my analysis code and I make some plots to compare?
>> >>>
>> >>> Sung
>> >>> Florida State University
>> >>>
>> >>>> Chuck had stated that the pull parameters are going to give you
>> >> moremeaningful information than the corrected energy. He should
know. Why
>> >> don't you do as he suggested, and show the center of the photon
>> pulls>> as a
>> >>>> function of photon energy?
>> >>>> Of course you are free to feel confident in the corrected
>> values of
>> >> thephoton energy given by your kinematic fitter. It is up to you to
find out
>> >>>> how best to make the photon pull parameters more reasonable. I
>> >> wouldconcentrate on the easiest thing first: Make the Carbon and
>> CH2>> targetshave reasonable pulls, and then work on the Butanol
target.>> Thatis just
>> >>>> me. It is your analysis.
>> >>>> Happy hunting.
>> >>>> Best wishes,
>> >>>> Michael
>> >>>>> Hi Dugger,
>> >>>>>
>> >>>>> I have made more updated histograms.
>> >>>>> The y-axis value has [E_calculated - E_measured] /
>> >> [E_measured] The
>> >> x-axis has [E_measured] or Z-vertex.
>> >>>>> You can check my results in the following web:
>> >>>>>
>> >>>>>    http://www.jlab.org/Hall-B/secure/g9/sungkyun/6-14-10.html
>> >>>>>
>> >>>>> I am sure that after applying the recent updated eloss
>> >>>> correction, the
>> >>>>> ratio of {E(cal. photon) - E(cal. photon)} to E(cal. photon) has
>> >>>> been> located near zero more. I think the current eloss is
>> >> improved more.>
>> >>>>> I do not know about the tagger sag. After eloss correction,
>> there>>>> are> still structure. that is, In the low energy,
>> measured photon
>> >> energy is
>> >>>>> bigger than calculated photon energy. However, the difference is
>> >>>> very> small when we compare them with the histogram which are
>> made>> before eloss.
>> >>>>> Do you think the reason of this difference is the tagger sag?
>> >>>>>
>> >>>>> Sung
>> >>>>>
>> >>>>> Florida State University
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>>
>> >>>>> ----- Original Message -----
>> >>>>> From: Michael Dugger <dugger at jlab.org>
>> >>>>> Date: Wednesday, June 9, 2010 4:34 pm
>> >>>>> Subject: Re: [Frost] tagger sag
>> >>>>> To: Sungkyun Park <sp06k at fsu.edu>
>> >>>>> Cc: frost at jlab.org
>> >>>>>
>> >>>>>>
>> >>>>>> Sung,
>> >>>>>>
>> >>>>>> I really hate to be a bother. From what I can tell, the plots
>> >> youshow are
>> >>>>>> from the kinematic fitter. The FSU kinematic fitter showed
>> >> the exact
>> >> same
>> >>>>>> kind of agreement for g8b. I do not know why. There were many
>> >> discussions regarding this. Please see
>> >>>>>> http://www.jlab.org/~dugger/tmp/meanValues_048326.A10.gif
>> >> (this plot
>> >> goes
>> >>>>>> along with the email I got from Charles Hanretty shown at the
>> >> bottom of
>> >>>>>> this email). Charles and I had the exact same conversations
regarding the
>> >>>>>> tagger sag for g8b.
>> >>>>>>
>> >>>>>> The pull parameters for the photon energy are a much better
>> >> gauge of
>> >> how
>> >>>>>> well the measured photon energy compares to the calculated
>> >> when using a
>> >>>>>> kinematic fitter. A kinematic fitter can not be relied upon
>> >> to give
>> >> accurate results when the pulls are not close to optimal. This
appears to
>> >>>>>> very much the case for the calculated photon energy using the
>> >> FSUkinematic fitter for g8b (and probably for g9a as well).
>> >>>>>>
>> >>>>>> You can see the difference in the pull parameters before and
>> >> after the
>> >>>>>> tagger sag correction for g8b data in Fig. 7 on page 8 of
http://www1.jlab.org/ul/Physics/Hall-B/clas/public/2009-030.pdf
>> >>>>>>
>> >>>>>> Your photon pulls shown on your web page at:
>> >>>>>> http://www.jlab.org/Hall-B/secure/g9/sungkyun/6-1-10.html Give
the following parameters:
>> >>>>>>
>> >>>>>> Carbon->
>> >>>>>> mean 0.122
>> >>>>>> sigma 1.124
>> >>>>>>
>> >>>>>> CH2->
>> >>>>>> mean 0.251
>> >>>>>> sigma 1.235
>> >>>>>>>>>>> For Chuck using g8b data:
>> >>>>>>
>> >>>>>> Before tagger sag correction->
>> >>>>>> mean 0.3027
>> >>>>>> sigma 1.219
>> >>>>>>
>> >>>>>> After tagger sag correction->
>> >>>>>> mean 0.0049
>> >>>>>> sigma 1.040
>> >>>>>>
>> >>>>>> At first glance, it looks entirely reasonable to suspect that
>> >> youhave the
>> >>>>>> same sort of photon energy problems that Chuck had.
>> >>>>>>
>> >>>>>> I also want to make it clear that the sag correction was
>> >> supposed to be
>> >>>>>> included in the g8b data and it was never determined what went
>> >> wrong. Why
>> >>>>>> should we assume that the tagger sag is fixed when it has not
>> >> beenverified?
>> >>>>>>
>> >>>>>> One more thing that might be of interest: It appears that the
>> >> [E_calculated - E_measured] is nearly perfect for the comparisons
done by the kinematic fitter. However, it would be very surprising to get
>> >>>>>> this same type of result from your most recent study at:
http://www.jlab.org/Hall-B/secure/g9/sungkyun/6-9-10.html
>> >>>>>>
>> >>>>>> I only propose that you find out [E_calculated -
>> >>>>>> E_measured]/E_measured using your most current study (without
>> >> kinematic>> >> fitter) and include enough statistics to get the
numbers to the 0.1%
>> >>>>>> level. This would serve as a way to verify that the tagger
>> >> sag is
>> >> correctly included in g9a.
>> >>>>>>
>> >>>>>> No matter what, you are going to have to get your photon
>> >> pulls to be
>> >> much
>> >>>>>> better before you can reliably use the kinematic fitter in your
>> >> analysis.
>> >>>>>> That is the price you pay for using such a powerful technique.
>> >>>>>>
>> >>>>>>
>> >>>>>> ************************
>> >>>>>> Date: Wed, 19 Aug 2009 15:18:41 -0400 (EDT)
>> >>>>>> From: Charles Hanretty <hanretty at hadron.physics.fsu.edu> To:
Michael Dugger <dugger at jlab.org>
>> >>>>>> Subject: Re: E(true) and E(meas)
>> >>>>>> Parts/Attachments:
>> >>>>>>    1 Shown    161 lines  Text
>> >>>>>>    2   OK      12 KB     Image
>> >>>>>> ----------------------------------------
>> >>>>>>
>> >>>>>> Mike,
>> > >> >>    Attached is a plot I have of the mean values generated from
>> >>>>>> just 1
>> >>>>>> 1.3GeV file
>> >>>>>> (cooked_048326.A10.B00).  I fit each slice of the
>> >>>>>> (Etrue/Emeas)vEmeas plot
>> >>>>>> by using the function
>> >>>>>> TH2::FitSlicesY (168 slices).  Looking at this, one could see
>> >> thesimilarity between this plot and
>> >>>>>> the one you showed at the meeting.  I've made this final plot
>> >> (Etrue-Emeas v Emeas) but it does not look how I expect it to or
want it
>> >>>>>> to
>> >>>>>> so I'm trying to figure out if I made an error somewhere.
>> >> One thing to
>> >>>>>> note
>> >>>>>> is that the differences between Etrue and Emeas (for me) seem
>> >> to be
>> >> smaller
>> >>>>>> than the differences you are dealing with.  This might
>> >> flatten out
>> >> some of
>> >>>>>> the bumps we're looking
>> >>>>>> for.  For example, your Etrue/Emeas v Emeas plot has a
>> >>>>>> y-range of 0.95-1.05.  I started off with this range but had
>> >> a lot of
>> >>>>>> empty
>> >>>>>> space and therefore have changed my y-range to 0.998-1.002.
Anyway, this
>> >>>>>> is an update; there is
>> >>>>>> still work to be done.
>> >>>>>>
>> >>>>>> -Chuck
>> >>>>>> *************************************88
>> >>>>>>
>> >>>>>> -Michael
>> >>>>>>
>> >>>>>>
>> >>>>>> On Wed, 9 Jun 2010, Sungkyun Park wrote:
>> >>>>>>
>> >>>>>>> Hi Michael,
>> >>>>>>>
>> >>>>>>> My understanding is that we do not worry about the problem
>> >> of the
>> >>>>>> tagger sag in FROST data.
>> >>>>>>> When we make the cooking file, that problem is corrected.
>> >>>>>>>
>> >>>>>>> I make a same plot made at g8b.
>> >>>>>>> The first plot is about E-id vs E{true photon beam} -
>> >> E{measured>> >> photon beam}
>> >>>>>>> The second plot is about E{measured photon beam} vs E{true
>> >> photon>> >> beam} - E{measured photon beam}
>> >>>>>>>
>> >>>>>>> These plots are made in topology #gamma p -> p #pi+ #pi- (all
>> >>>>>> detected) and the updated eloss correction is applied.
>> >>>>>>> E{measured photon beam} is the initial photon energy.
>> >>>>>>> E{true photon beam} is the photon energy after kinematic
>> >> fitting.I used 0.05 as the confidence level cut. I used only a run
55570>> >> in period 3. The electron beam energy of period 3 is
1.645 GeV. So
>> >> The energy range of E{measured photon beam} is from 0.33 GeV to
>> 1.56>> GeV.
>> >>>>>>> When we compare plots in CLAS-NOTE with plots attached with
>> >> this>> >> email, FROST data do not have any problem of the
>> tagger sag.
>> >>>>>>>
>> >>>>>>> Sung
>> >>>>>>> Florida State University
>> >>>>>>>
>> >>>>>>>
>> >>>>>>> ----- Original Message -----
>> >>>>>>> From: Michael Dugger <dugger at jlab.org>
>> >>>>>>> Date: Wednesday, June 9, 2010 1:04
>> >>>>>>> Subject: [Frost] tagger sag
>> >>>>>>> To: frost at jlab.org
>> >>>>>>>
>> >>>>>>>>
>> >>>>>>>> Hi,
>> >>>>>>>>
>> >>>>>>>> I know that the study Sungkyun performed was to help
>> >> verify the
>> >> eloss
>> >>>>>>>> momentum corrections, and I think that this is a reasonable
>> >>>> way to
>> >>>>>>>> look at
>> >>>>>>>> his study. However, this sort of study is also very useful in
>> >> determining
>> >>>>>>>> the tagger sag. Since the eloss correction is not as
>> >>>> pronounced for
>> >>>>>>>> the
>> >>>>>>>> Carbon and CH2 targets, these targets can give us a good
>> >>>> picture on
>> >>>>>>>> the
>> >>>>>>>> tagger sag situation.
>> >>>>>>>>
>> >>>>>>>> If you look at the CLAS note:
>> >>>>>>>> http://www1.jlab.org/ul/Physics/Hall-B/clas/public/2009-
>> >> 030.pdf>> >> >>
>> >>>>>>>> Fig. 5 on page 6 shows the tagger sag correction to be on the
>> >>>> order>> >> of
>> >>>>>>>> 0.5% for g1c data. For g8b data, the sag correction was
>> >>>> between 0.2
>> >>>>>>>> to
>> >>>>>>>> 1.0% (Fig. 6 page 7). This means that we need to look for
>> >> energyeffects
>> >>>>>>>> on the order of 0.1% to be sure that the tagger sag is not an
>> >>>>>> issue.>>
>> >>>>>>>> For g8b it was found that the tagger sag correction was
>> >>>> important>> >> in
>> >>>>>>>> obtaining reasonable pulls for the FSU kinematic fitter (see
>> >>>> table>> >> 1 on
>> >>>>>>>> page 7).
>> >>>>>>>>
>> >>>>>>>> One way to get a better look at the energy study is to use:
>> >> [E_calculated - E_measured]/E_measured
>> >>>>>>>> instead of
>> >>>>>>>> E_calculated/E_measured.
>> >>>>>>>>
>> >>>>>>>> Since Mike Williams used this sort of parametrization for g1c
>> >>>> (and>> >> I
>> >>>>>>>> did the same for g8b), we can more easily compare results
>> >>>> between>> >> the
>> >>>>>>>> different run periods to see if the shape of the energy
>> >>>> correction>> >> distributions look similar. The tagger sag has a
>> >> "signature" three
>> >>>>>>>> bump
>> >>>>>>>> pattern that should be clearly visible once we get to the
>> >> 0.1%>> >> level.>>
>> >>>>>>>> -Michael
>> >>>>>>>> _______________________________________________
>> >>>>>>>> Frost mailing list
>> >>>>>>>> Frost at jlab.org
>> >>>>>>>> https://mailman.jlab.org/mailman/listinfo/frost
>> >>>>>>>>
>> >>>>>>>
>> >>>>>>
>> >>>>>
>> >>>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >