add a couple of improvements to the quad fitter and fix a bug in get_hough_transform()

This commit adds two improvements to the quad fitter:

1. I updated quad to weight the random PMT hit selection by the probability
that the PMT hit is a multiphoton hit. The idea here is that we really only
want to sample direct light and for high energy events the reflected and
scattered light is usually single photon.

2. I added an option to quad to only use points in the quad cloud which are
below a given quantile of t0. The idea here is that for particles like muons
which travel more than a few centimeters in the detector the quad cloud usually
looks like the whole track. Since we want the QUAD fitter to find the position
of the *start* of the track we select only those quad cloud points with an
early time so the position is closer to the position of the start of the track.

Also, I fixed a major bug in get_hough_transform() in which I was using the
wrong index variable when checking if a PMT was not flagged, a normal PMT, and
was hit. This was causing the algorithm to completely miss finding more than
one ring while I was testing it.

1 files changed, 5 insertions, 1 deletions

diff --git a/src/quad.h b/src/quad.h
index 51ff6ee..e95ae37 100644
--- a/src/quad.h
+++ b/src/quad.h
@@ -19,12 +19,16 @@
 
 #include "event.h"
 #include <stdlib.h> /* for size_t */
+#include <gsl/gsl_rng.h>
 
 /* Maximum number of quad cloud points. */
 #define QUAD_MAX 10000
 
+/* Maximum number of PE to consider when calculating P(> 1 hit|q) */
+#define QUAD_MAX_PE 10
+
 extern char quad_err[256];
 
-int quad(event *ev, double *pos, double *t0, size_t npoints);
+int quad(event *ev, double *pos, double *t0, size_t npoints, double f);
 
 #endif