hi everyone,
it was pointed out that i didn't give any estimates for the errors for the asymmetries i sent out earlier. sorry about that. also, my message said i calculated the asymmetries for 11-2, but really it should have said 11-4. so here are my estimates for the uncertainty in these asymmetries:
(dA = sqrt((1-A^2)/(Npleft + Npright)), where I have used dNpleft = sqrt(Npleft), dNpright = sqrt(Npright), and Npleft is the number of events in the peak when the proton is on the left, etc.)
Acut
dAcut
-----------------------------------------------------------------
11-4 +11.3%
+/- 3.0%
12-2 -2.2%
+/- 2.6%
12-3 -2.2%
+/- 1.8%
12-4 +3.4%
+/- 1.4%
so, the asymmetries are of the same order of magnitude as the statistical uncertainty, but still not so good. note however, that these numbers include only a few runs. i have looked briefly at the asymmetries with more runs and i didn't notice the asymmetries being much smaller than above. of course, the statistical uncertainty goes down if you include more runs, so if someone repeats this with more runs we may have a better idea of whether the asymmetries are larger than the statistical error in the asymmetries or not.
thanks,
jason
Jason Seely wrote:
Hall was open.I worked on asymmetry study, notes are in the log book.
Basically I just used show_protons.C and applied a timing cut on the TDCdiff spectra to isolate the proton peak. This works ok, but asymmetries are still a few percent. Since this process is really slow (show_protons.C is really slow when it has to make cuts), I changed the loop in show_protons to only do one set of paddle combinations at a time (for example, today i did 0-4 with 11-15), which speeds things up by a factor of 4, but is still pretty slow. Anyway, it has been suggested that a coplanarity cut in addition to the timing cut may help. I started to work on this, but lost about an hour due to the power outage at 3pm. Computers came back online shortly before 4pm.
Here's a table of the asymmetries: (A = (Npleft - Npright)/(Npleft + Npright))
comb. Auncut Acut
------------------------
11-2 -5% +11.3%
12-2 +4% -2.2%
12-3 +2% -2.2%
12-4 +4% +3.4%JS HK
-- -------------------------------------------------------------------- jason seely 26.650.b massachusetts institute of technology 77 massachusetts avenue cambridge, ma 02139-4307 email: seely@mit.edu phone: 617.253.4772/6734 html: web.mit.edu/seely/www --------------------------------------------------------------------
-- -------------------------------------------------------------------- jason seely 26.650.b massachusetts institute of technology 77 massachusetts avenue cambridge, ma 02139-4307 email: seely@mit.edu phone: 617.253.4772/6734 html: web.mit.edu/seely/www --------------------------------------------------------------------
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