Re: Thoughts on motivating tof for Review

[beni zihlmann <bzihlman@indiana.edu>]

Hi All,

attached are 4 plots. The first two show the TOF in bcal for 65cm and 
90cm fight path
or 90 degree and 45degree polar angle. The dotted line indicates 3 sigma 
from the
center. Where two dotten lines cross indicates the peak separation of 6 
sigma.
The assumed timing resolution in BCAL is 250ps.
The next two plots show the momentum distributions for protons pions and 
kaons
all positive charges only that gets stopped in the BCAL. The events are 
from 2M pythia
generated events and then run through hdgeant.
The relative multiplicities are around 1-5 between protons and pions in 
the momentum
region where there are protons. At the very low momentum region there 
are only pions.
Kaons however are always at least a factor of 10 and more less abundant. 
At smaller angles
even higher momenta are possible.
In general any PID in BCAL beyond 0.8GeV is very very difficult.
To emphasize that a 6 sigma separation is needed I made the last plot 
showing in read blue
and purple what happens when the left peak is the same or 100 larger or 
smaller than
the right peak. While the gray curve shows the running integral of the 
left peak. If
the peaks would be separated only by 3 sigma reasonable PID of uneven 
peaks would
be very difficult.

cheers,
Beni

bcalres_65cm_tof_250ps.eps.gz

bcalres_90cm_tof_250ps.eps.gz

pdist_barrel_z62.eps.gz

pdist_barrel_z122.eps.gz

pid_6sigma_separation.eps.gz