[G12] pKp[Km] ntuple

Thu Nov 3 09:17:40 EDT 2011

Yup, sorry about that. The label on the x-axis is wrong it should read
"M(K+K-)" and as the filename indicates it is the invariant mass of the
K+K- where the K- was obtained through missing mass (and kinematically fit)
-- So it really is the missing mass off the proton, but now its semantics
since those are equal after the kinematic fit. Anyways, I updated the
figure with the statistics I got over night and attached it.

This data represents about 50% of g12 and exactly 354 complete runs where I
have cut out the "tripped" regions which were not included in the flux
calculation. I am in the process of getting the rest of the data now. If
you don't care about the flux for this analysis, I can get you 95% of the
data by tomorrow I think.

As far as basic cuts, here they are:
1. I require "complete" information from the track fitter. Specifically,
the TDPL bank had to have positions and local angles for the planes at the
start counter and time-of-flight counters.
2. The start counter and TOF hit had to be associated with the track
_during_ the reconstruction. I.e., the ST and TOF hit shows up in the TBID
bank.
3. vertex timing cuts are as such for each detected particle (in this case,
the proton and the K+):
    dt_vtx_pid = t_vtx(TAG) - t_vtx(TOF, Beta_momentum[PID})
    dt_vtx_st = t_vtx(TAG) - t_vtx(ST,TOF)
where t_vtx(TAG) is the vertex time according to the tagger hit, t_vtx(TOF,
Beta_momentum[PID}) is the vertex time according to the TOF where I got
beta from the particle ID and the momentum in the DC, and t_vtx(ST,TOF) is
the vertex time according to the hits in the ST and TOF. The path lengths
were obtained from the TDPL bank in the latter two.
4. There was a mass cut on both the proton and K+:
    abs(M_measured - M_book) < M_cut
where M_cut is 62.4 MeV for the proton and 60 MeV for the K+
5. There were a few tagger timing cuts as well:
    abs(t_tag - t_pho(PID)) < 1
    abs(t_tag - t_pho(ST,TOF) < 1
where t_tag is the RF corrected tagger time for the selected tagger hit,
and t_pho(PID) and t_pho(ST,TOF)) are the tagger times in a similar vein as
the vertex times of cut #3 above.
6. There was a cut on the missing mass off the proton and K+ (around the
K-):
    abs(M_Km_measured - M_Km_book) < M_Km_measured
7. the minimum probability after the kinematic fit (pK+ to a missing K-)
was 0.01 (equivalently, 1%).

I am including plots which illustrate all but the last two cuts in my
analysis note on cascades since they are (slightly) different from what I
used in my dissertation. The cuts 1-5 (where the K+ is concerned) are part
of the skim I made so changing them would take a long time (month or so).
Cuts 1-5 for the proton or cuts 6 and 7 can be changed in a day but I think
they should be broad enough for any analysis, especially since the
resulting four-vectors are post-kinematic fit.

It occurred to me you may need the vertex positions of the proton and K+.
Let me know if you do and I can redo the ntuple.

On Wed, Nov 2, 2011 at 8:48 PM, Alex Kubarovsky <kubarovsky at gmail.com>wrote:

> Dear Johann,
>
> I think the picture you attached is missing mass to proton with K+
> detected, am I wrong?
>
> Thank you, Alex
>
> On Wed, Nov 2, 2011 at 4:24 PM, Johann Goetz <jgoetz at ucla.edu> wrote:
>
>> Hi all,
>> I was not sure who to send this to so I sent it to the g12 mailing list.
>> I am outputting a small ntuple of proton K+ events where I have
>> kinematically fit to a missing K- with a probability selection of >1%. I
>> have briefly looked at the data to make sure the numbers are reasonable
>> (see phi(1020) peak attached).
>>
>> I am copying the files here:
>>     /volatile/clas/clasg12/goetz/pkp_km_kfit_ntuple
>>
>> The files I have processed so far are __complete_runs__ meaning that
>> every event was considered in the given run. e.g. the file
>> kaon.good.56363.txt includes all data from run 56363 ("good" here means
>> non-trip regions). These are plain-text files and the first two lines are
>> header information: first line is column label and the second line is
>> column type: i4 = int, f4 = float.
>>
>> I included the run and event number, the beam energy (ebeam) and the
>> four-momenta of the three particles p, kp, and km. The other columns are
>> the results from the kinematic fit. The one you might want to look at is
>> "kfitprob". I made a selection on this variable at >1%, but you might want
>> to first increase this to 10% if you find you have any background you can't
>> explain.
>>
>> >head -3 kaon.good.56363.txt
>> run event kfitprob kfitchi2 kfitpull_ebeam kfitpull_p_mom kfitpull_p_lam
>> kfitpull_p_phi kfitpull_kp_mom kfitpull_kp_lam kfitpull_kp_phi
>> kfiterr_km_mom kfiterr_km_lam kfiterr_km_phi ebeam p_e p_px p_py p_pz kp_e
>> kp_px kp_py kp_pz km_e km_px km_py km_pz
>> i4 i4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4 f4
>> f4 f4 f4
>> 56363 40481 0.619477 0.246603 -0.507221 0.367299 0.49034 -0.507834
>> 0.513646 -0.477136 0.501621 0.018267 0.0236273 0.0236293 2.9719 1.12352
>> -0.0508986 -0.243942 0.565551 1.80493 0.366565 0.431194 1.64126 0.981723
>> -0.315666 -0.187252 0.765084
>> ...
>>
>> --
>> Johann T. Goetz, PhD. <http://sites.google.com/site/theodoregoetz/>
>> jgoetz at ucla.edu
>> Nefkens Group, UCLA Dept. of Physics & Astronomy
>> Hall-B, Jefferson Lab, Newport News, VA
>> Office: 757-269-5465 (CEBAF Center F-335)
>> Mobile: 757-768-9999
>>
>>
>> _______________________________________________
>> G12 mailing list
>> G12 at jlab.org
>> https://mailman.jlab.org/mailman/listinfo/g12
>>
>>
>

-- 
Johann T. Goetz, PhD. <http://sites.google.com/site/theodoregoetz/>
jgoetz at ucla.edu
Nefkens Group, UCLA Dept. of Physics & Astronomy
Hall-B, Jefferson Lab, Newport News, VA
Office: 757-269-5465 (CEBAF Center F-335)
Mobile: 757-768-9999
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