Hi Chi-
Well maybe these plots are not impressive but I am still working
in a rough draft way just to get mass cuts. Anyway, I have skimmed some
D2 runs with the cuts:
-3 different tofs must fire (i.e. have good tdc)
-must have at least 3 tracks all w/chi^2 < 1
-must have at least two positive tracks in different groups
with these cuts I crunched about 7 runs at 500K each and retained about 70
events per run. I played with the binning and in two of the plots you can
see the proton, pion, and electron peak. I then rebinned again and found
that the proton peak became more defined while the pions and the electrons
merged. Anyway, it seems to work quite nicely. I am glad I tried to do
things myself (i.e. create my own mass function) though as it gave me a
great appreciation for what you have
done. (Good Job, I will use your function!) Anyway, thanks. Based on
these plots, I will choose to record events with the above cuts plus:
- 2 independent positive tracks with (0.6 GeV < mass < 1.2 GeV)
- at least 1 negative track with:
(0.05 GeV < mass < .35 GeV) for pions
(mass < 0.05 GeV) for electrons
Then I will place these into groups of either:
1: p, p, pi-
2: p, p, e-
3: p, e-, pi-
as we will very likely lose either the e-, p, or pi- in our minute
coverage which is but a fraction of 4*Pi.
Pete
----------------------------------------------
Pete Karpius
Graduate Research Assistant
Nuclear Physics Group
University of New Hampshire
phone: (603)862-1220
FAX: (603)862-2998
email: karpiusp@einstein.unh.edu
http://pubpages.unh.edu/~pkarpius/homepage.htm
----------------------------------------------
---------- Forwarded message ----------
Date: Tue, 20 Jan 2004 11:25:41 -0500 (EST)
From: Peter Karpius <karpiusp@einstein.unh.edu>
To: jrc@physics.unh.edu
Cc: calarco@unh.edu, tong@lns.mit.edu, asindile@cisunix.unh.edu
Subject: mass
Hi John-
I have started using a function called Mass() that Chi uses in
PID. I have included this in my code and run it on about seven runs at
500K events each. Attached are mass plots. It seems that one can resolve
the proton and pion peak. In one plot I have changed the binning which
better defines the proton peak but merges the pions with the electrons.
I am wondering if I can now make mass cuts based on these plots. For
instance, only record events with:
- 2 independent positive tracks with (0.6 GeV < mass < 1.2 GeV)
- at least 1 negative track with:
(0.05 GeV < mass < .35 GeV) for pions
(mass < 0.05 GeV) for electrons
-are these cuts too loose?
Also, if I am not mistaken, I believe that this mass function still must make
an assumption on the first particle mass and uses this to get vertex time
(TOF).
Please take a look at these plots and tell me what you think.
Thanks-
Pete
----------------------------------------------
Pete Karpius
Graduate Research Assistant
Nuclear Physics Group
University of New Hampshire
phone: (603)862-1220
FAX: (603)862-2998
email: karpiusp@einstein.unh.edu
http://pubpages.unh.edu/~pkarpius/homepage.htm
----------------------------------------------
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