Photon Reconstruction in b1pi events 02/10/2012

BCAL

Thrown photons

For comaparision, useful to use z rather than theta

Reconstructed photons

Where does each of these peaks come from?

A timing cut fabs(t_shower-t_flight) < 1 ns can be applied to remove many of the extra "photons".

I don't think low energy showers are well understood at the moment, so remove clusters with E<60 MeV.

Also, cut out a problem area at forward angles and lower energies (E<150 MeV && z>300 cm)

Red shows the effect of the timing cuts. Blue shows all the cuts above.

With all cuts:

Number of "photons" decreases from x to y.

Two gamma invariant Mass

Look at pairs of 2 BCAL photons and 1 BCAL+1 FCAL photon, with the cuts described above. Using truth vertex information.

Compare KLOE algorithm to GlueX algorithm.

Black is KLOE, red is GlueX. Fits are to gaussian + straight line.