This week I've spent most time looking at neutron arm variables in
conjuntion with BigBite tracks.  I have also spent considerable
time in preparation to migrate to a new database system.  Currently,
we have scripts available to copy all of the BigBite detectors into
the MySQL database.  Work must be done to rewrite the ReadDatabase
functions in the detector classes which will be done once an API
is supplied.

Description of plots:

Tracking:

residual-0000.ps - residuals as they have been
residual-cellrest.ps - Implemented cell restrictions and plotted residuals

pdiff-nocell.ps - Momentum resolution without cell restrictions
pdiff-withcell.ps - Momentum resolution with cell restrictions

Note that adding in cell restrictions decreases the number of tracks
by about 20% in the elastic peak using identical cuts.  Residuals, while
outliers are removed, do not improve significantly in the main peak.

Neutron Arm:

tofres-nocorr.ps - Time of Flight resolution, no corrections
tofresvsbar-nocorr.ps - Time of Flight resolution vs bar number, no corrections

tofres-corr.ps - Time of Flight resolution, corrections
tofresvsbar-corr.ps - Time of Flight resolution vs bar number, corrections

Added in minor corrections to the time of flight calculation.  This was done 
by lining up mean values between bars using only elastic events.

napres.ps - Neutron arm momentum resolution for elastics

n1x-v1x.ps - Veto 1 vertical position - N1 vertical position

Tight correlation allows us to select veto signal events and non-veto signal
events.  Used a cut of +/-0.2m

nap-elastics.ps - Momentum for particle of assumed mass 0.938GeV for elastics
		Black - All events
		Red   - Events with associated veto hit
		Blue  - Events without associated veto hit (no signal)

nap-full.ps - Momentum for particle of assumed mass 0.938GeV for all events
		Black - All events
		Red   - Events with associated veto hit
		Blue  - Events without associated veto hit (no signal)


Here we see some interesting effects.  Protons are detected mostly when
selecting on elastics.  However, there appears to be some structure in the
lower momentum region outside of what we expect for elastics.  These also
appear to have a higher chance of not creating a veto signal.  Pi0s?  If
they are indeed particles of a different mass, the momentum plotted is not 
correct.

edepvsp-elas.ps - Energy deposition vs momentum - Elastic events
edepvsp-full.ps - Energy deposition vs momentum - All events

Here we see elastic events cluster nicely in a specific area.  We see
that the particles in the lower momentum region separate out away from
the elastic region into one or two groups suggesting different particle
types.  More analysis should be done to try and understand these events.

- Seamus Riordan
  riordan@jlab.org
  August 8, 2006