[Hallc_sidis_analysis] [EXTERNAL] SIDIS Analysis Meeting tomorrow (FRIDAY) at 1:00 PM EDT

[bosted at jlab.org]

Hi all,
   If you wish to put a cut and related efficiency correction
on the number of reference TDC signals, you can use the
variable:
T.coin.pT2_tdcMultiplicity
   I cut on events with >5 hits.
   Correspondingly, you should find the efficiency for
events with a good TDC and ADC reference time values to
be higher.
   I recommend to use Mark's new version of hcana.

   The remaining deadtime in the aerogel and HG will depend on
how wide your ADC windows are. For the HG, with only
4 PMT's the effect can be bigger. The FADCs have a
minimum 100 nsec between pulses, so if you have a
random hit just before your good one, it might get
lost.

  Regarding tracking efficiency, I found that there
is almost always a track, but that the efficiency for
a "good" track can be as low of 0.88 at high rates.
I define "good" as having -25<pdelta<50%, and
abs(xptar)<0.07 and abs(yptar)<0.070 rad and
abs(ytar)<50 cm. Since the drift times are up to
200 nsec (I think), at high rates random "sprinkle"
hits can come earlier than the actual hit time, as
distort the drift time. And, lots of extra wires
get hits that don't belong with the track. You
may want to tighten some of the tracking criteria
(number clusters, number planes, etc.). Also
important to have tracking pruning turned on and
reasonable pruning parameters.

   After the meeting, Varden found that some studies
were done that showed that proton and kaons would
make signals below threshold due to knock-on
(delta-ray) electrons, mostly coming from the HG
gas detectors and the front hodoscope, both of
which are in front of the aergel. In addition, the
aerogel has a tail extending to higher npe due to
decays to mu nu or pi pi somewhere in the detector
hut. About 20% of them at 3 GeV. I will try to
write up my findings on kaon decays. The good news
is that if they decay before the hut, they
essentially never make it past our cuts, so the
cointime spectrum is not shifted.

   I have decided in my code to store the RF time
spectrum for each of my kinematic bins in z,
and do a two parameter fit for the pi and K peaks,
since they overlap and are not emeable to separation
by cuts on aerogel and/or HG without reducing
the pion efficiency. This is what was done in
the 6 GeV experiment, as I recall.

   If you want to run SIMC for sSIDIS kaons, I
highly recommend to fix a bug in the code around
line 379, where there is a "+" instead of "*"
in front of "ssea" in the formula for K+ from protons.

   If you want a proper treatment of kaon decays,
I recommend to use my version of
/group/c-sidis/bosted/simc/shared/transp.f
The previous version only worked correctly for pions.

   If you want to try my improved treatment of
exclusive pions (using MAID for W<2 GeV), you can try
/group/c-sidis/bosted/simc/physics_pion.f
The previous version just used PARAM3000 for all
values of W, but the fit isn't well constrained
at low W and can give quite inaccurate results.
Dave Gaskell is testing my new code for bugs:
hopefully he won't find too many.

    Hem and Jia, don't forget to include the low-pt runs
from pt-SIDIS in your analysis (if your advisors agree, of
course).  Officially, these points
were overlapped between pt-SIDIS and CSV, to avoid
taking these runs twice. Since the Spring18 runs have
several issues on their own, I can provide you with
corrected yields for those runs to work with, if you
wish. The Fall18 runs that we took back-to-back all
have the same complications, so should be very easy
to add to your analysis, however (starting with run 5368).

   My two big priorities for the future are:

1) try to get a good model for e p -> e pi - Delta++

2) figure out why the missing mass peak for exclusive
pion production is around 0.90 (spring 18) or 0.92
(after that) instead of 0.94, at least when
HMS momentum is 5.27 GeV (which is most of the
pt-sidis experiment).

3) continue refining PID, luminosity corr. rho background, 


Aloha,

Peter


> Hi All,
> We will have the regular CSV analysis meeting tomorrow (Friday) at 1:00 PM
> EDT
>
> The Meeting URL is
> https://urldefense.proofpoint.com/v2/url?u=https-3A__bluejeans.com_341030850&d=DwIBaQ&c=CJqEzB1piLOyyvZjb8YUQw&r=6UVi9h7XDe4YpNVl1Pr7kJfw2N_A9rNcjJ8jEvLZw2M&m=jp9eWTO0zoC-Abhf7MlVvHzGSJhW80l7M4WcHULdpyU&s=acaaPkEJfO4gimzWYYuGYf5XbgsXvQ7joq-sETChMKU&e=
>
> Please plan on showing a few slides on your work and please upload the
> slides to the SIDIS elog at:
> https://hallcweb.jlab.org/elogs/SIDIS+Pt+and+CSV+Experiments+Analysis
>
>
> Cheers
> Dipangkar
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