User name jinhuang
Log entry time 18:27:58 on April 18, 2008
Entry number 232908
This entry is a followup to: 232729
keyword=Identifying Pi0 Missing Mass PeakThe following missing mass spectrum has been produced by following
these steps:
1. Base on production run 3282 (Kinematic G, 1M Events)
2. Cut on 1 track on Bigbite, 1 track on L-HRS event
a) Plot missing mass spectrum with events, which are 30ns within
coincidence peak
b) Plot missing mass spectrum with events, which are 30ns out of
coincidence peak
3. The final spectrum is Histogram (a) - Histogram (b)
Blue lines have an extra cut on W between 1073 and 1093 MeV, while red
line is cut by W between 1050 and 1070 MeV. Black curve is an Gaussian
fit of the blue plot.
It~{!/~}s obvious that a pi0 missing mass peak is formed after pi0
threshold. The shift and broadening of the peak are believed to be
caused by rough bigbite optics and tracking.
Currently, there are only 2 fitted parameter in bigbite optics model,
and it is only calibrated with 700MeV elastic proton. Identification of
pi0 peak has offered a second opportunity to further tune this model.
A copy of this log entry has been emailed to: jinhuang@mit.org
Plot of Invariant Mass of Recoil Sys.
Plot of Missing Mass