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, 20 insertions, 0 deletions

diff --git a/src/sno_charge.c b/src/sno_charge.c
index f0d38ec..130df9f 100644
--- a/src/sno_charge.c
+++ b/src/sno_charge.c
@@ -116,6 +116,26 @@ double get_qhi(void)
     return qhi;
 }
 
+double get_qmean(void)
+{
+    if (!initialized) {
+        fprintf(stderr, "charge interpolation hasn't been initialized!\n");
+        exit(1);
+    }
+
+    return qmean;
+}
+
+double get_qstd(void)
+{
+    if (!initialized) {
+        fprintf(stderr, "charge interpolation hasn't been initialized!\n");
+        exit(1);
+    }
+
+    return qstd;
+}
+
 static double nlopt_log_pq(unsigned int n, const double *x, double *grad, void *params)
 {
     int i;