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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.
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This commit updates guess_energy() which is used to seed the energy for the
likelihood fit. Previously we estimated the energy by summing up the charge in
a 42 degree cone around the proposed direction and then dividing that by 6
(since electrons in SNO and SNO+ produce approximately 6 hits/MeV). Now,
guess_energy() estimates the energy by calculating the expected number of
photons produced from Cerenkov light, EM showers, and delta rays for a given
particle at a given energy. The most likely energy is found by bisecting the
difference between the expected number of photons and the observed charge to
find when they are equal.
This improves things dramatically for cosmic muons which have energies of ~200
GeV. Previously the initial guess was always very low (~1 GeV) and the fit
could take > 1 hour to increase the energy.
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This commit updates the flasher cut to flag events in which the PMT with the
highest pedestal subtracted QLX charge is 80 counts above the next highest QLX
charge, has at least 4 hits in the same slot, and passes the final check in
the flasher cut (70% of the normal PMT hits must be 50 ns after the high charge
channel and 70% of the normal PMT hits must be at least 12 meters away from the
high charge channel).
This update was motivated by run 20062 GTID 818162. This was a flasher event
but which had only 3 hits in the PC and so passed the previous version of the
cut. This new update was inspired by the SNO QvT cut.
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This commit updates the flasher cut with the following changes:
- no longer require nhit to be less than 1000
- update charge criteria to be that the flasher channel must have a QHS or QHL
1000 counts above the next highest QHS or QHL value in the PC or a QLX value
80 counts above the next highest QLX value
- only check is_slot_early() for missing hits in the PC
These updates were inspired by looking at how to tag flashers in runs 20062 -
20370 which didn't fail the original cut. In particular, the following flashers
were previously not tagged:
Run GTID Comments
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20062 818162 flasher with only 3 hits in PC
reconstructs at PSUP
ESUMH triggered
20083 120836 high charge missing (in next couple of events)
probably picked wrong flasher PMT ID
20089 454156 nhit > 1000
After this commit the last two are properly tagged.
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This commit updates the QvNHIT cut to not require PMT hits to have a good
calibration to be included in the charge sum. The reason for this is that many
electrical pickup events have lots of hits which are pickup and thus have small
or negative charges. When the charge is low like this the PMT hits get flagged
with the bad calibration bit (I'm not sure if it's because of the PMT charge
walk calibration or what). Therefore, now we include all hit PMTs in the charge
sum if there ECA calibrated QHL value is above -100.
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This commit updates the zebra code to store a pointer to the first MAST bank in
the zebraFile struct so that we can jump to it when iterating over the logical
records. I had naively assumed based on the documenation in the SNOMAN
companion that the first bank in a logical record was guaranteed to be a MAST
bank, but that doesn't seem to be the case. This also explains why I was
sometimes seeing RHDR and ZDAB banks as the first bank in a logical record.
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This commit updates the breakdown cut to flag any event in which less than 70%
of the PMT hits have a good TAC value.
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This commit updates the a and b parameters for the gamma distribution used to
describe the position distribution of shower photons produced along the
direction of the muon. Previously I had been assuming b was equal to the
radiation length and using a formula from the PDG to calculate a from that.
However, this formula doesn't seem to be valid for muons (the formula comes
from a section describing the shower profile of electrons and gammas, so it's
not surprising). Therefore, now we don't assume any relationship between a and
b.
Now, the value of a is approximated by a constant since I couldn't find any
functional relationship as a function of energy to describe a very well (and
it's approximately constant), and b is approximated by a single degree
polynomial fit to the values I got from simulating muons in RAT-PAC as a
function of energy.
Note that looking at the simulation data it seems like the position
distribution of shower photons from muons isn't even very well described by a
gamma distribution, so in the future it might be a good idea to come up with a
better parameterization.
Even if I stick with the gamma distribution, it would be good to revisit this
in the future and fit for a and b over a wider range of energies.
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This commit adds the sub_run variable to the ev array in the HDF5 output file
and updates plot-energy to order the events using the run and sub_run
variables. This fixes a potential issue where I was sorting by GTID before, but
the GTID can wrap around and so isn't guaranteed to put the events in the right
order.
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This commit updates the ITC cut to use the pt1 time which is the ECA + PCA
without charge walk calibration time. The reason is that an event which is
mostly electronics noise may have all low charges which can't be calibrated
with the PCA walk calibration.
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This commit updates the ev.nhit variable to represent the total number of
normal PMTs hit in the event, regardless of if the calibration failed. I added
a new variable ev.nhit_cal which now stores the total number of normal PMTs hit
without any flags.
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This commit adds a field to the pmt_hit struct called best_uncal_q which
represents the best ECA calibrated charge (in units of QHS counts above
pedestals). This is then used in the muon data cleaning cut.
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This commit updates the muon cut to require at least 1 OWL hit which has a high
charge and is early relative to nearby normal PMTs. This replaces the previous
cut criteria which required 2 OWL hits to be early relative to the 10%
percentile of all the normal PMT hits.
This new cut should target external muons better although I still need to do
some testing. In the future I'd like to optimize the distance at which PMTs are
considered nearby. Currently I just use 3 meters which seemed like a good value
based on some initial testing.
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This commit updates is_slot_early() to do the following:
- use median time when checking to see if the time of the PMT hits in the slot
is early relative to nearby PMTs
- return True if the number of nearby PMTs is less than or equal to the number
of hit PMTs in the potential flasher slot
- skip potential cross talk hits when finding the nearby hit PMTs by skipping
hits in the adjacent slots with the same paddle card as the potential flasher
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This commit updates get_event() to assume the PMT type is correct in the
pmt.txt file instead of assuming the SNOMAN bank is correct. The reason for
this is that according to the email from Stan 3/15/9 should be a neck PMT (at
least in the NCD phase) and that is what the pmt.txt file says it should be. In
addition, the changes that Stan said were needed in ccc_type.for never got
made.
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This commit updates is_muon() to use the EHS charge for the OWL tubes since
based on looking at the charges for the OWL tubes it looks like the QHS values
are completely random.
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This commit updates get_event() to fill in the uncalibrated charge and time
info from the calibrated charge and time. The ECA calibrated time and ECA + PCA
without walk correction times (ept and pt1) are just set to the calibrated
time. The uncalibrated charges are set by multiplying the calibrated charge by
the mean high-half point and adding a constant offset, and the ECA calibrated
charges are set by taking the uncalibrated charges and subtracting the offset.
The reason for filling these in is so that we can test the data cleaning cuts
on MC. Although it would be better if these were filled in by the MC, this is
better than nothing.
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This commit updates the zebra code to properly handle all the errors from
get_bytes(). I also updated fit and cat-zdab to not display the errors about
the FTX banks by default unless you run them with the -v command line option.
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This commit fixes the FTS cut so that it returns 1 when the event is flagged as
failing the cut. Previously, the function returned the following:
not enough PMT pairs: 0 (fail)
median time > 6.8 ns: 0 (fail)
otherwise: 1 (pass)
This had two issues: the return value wasn't consistent with the rest of the
data cleaning cuts and it should pass if there aren't enough PMT pairs.
Now, I fixed the not enough PMT pairs case and made the return value consistent
with the rest of the data cleaning cuts:
not enough PMT pairs: 0 (pass)
median time > 6.8 ns: 1 (fail)
otherwise: 0 (pass)
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This commit updates the second requirement of the neck event tag to flag events
in which either 50% of the normal PMT hits are at the bottom of the detector
*or* 50% of the ECA calibrated charge is at the bottom of the detector.
This update was added after testing the cut out on run 10058 which is not in
the golden run list and noticing that there were 4 events which were very
clearly neck events but which didn't get tagged.
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This commit fixes a bug in get_shower_weights() and get_delta_ray_weights()
which was causing an inf value to propagate and cause the fitter to crash. The
problem came because due to floating point roundoff the cdf value at the end of
the loop was slightly greater than the last cdf value we wanted which was
causing it to get mapped to cos(theta) = -1 (I think?) and then subsequently
get interpolated to an infinite value for xcdf.
The fix is just to make sure that the x coordinate is always between x1 and x2.
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This commit updates the charge spectrum initialization to convolve the charge
distribution over a wider range to make sure that we have a nonzero probability
of observing charges all the way down to qlo.
The reason for this is that previously for some negative charges the
probability of observing that charge was zero, which was causing the likelihood
to return nan.
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This commit updates the fit program to accept a particle combo from the command
line so you can fit for a single particle combination hypothesis. For example
running:
$ ./fit ~/zdabs/mu_minus_700_1000.hdf5 -p 2020
would just fit for the 2 electron hypothesis.
The reason for adding this ability is that my grid jobs were getting evicted
when fitting muons in run 10,000 since it takes 10s of hours to fit for all the
particle hypothesis. With this change, and a small update to the
submit-grid-jobs script we now submit a single grid job per particle
combination hypothesis which should make each grid job run approximately 4
times faster.
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This commit updates get_event() to flag PMT charges below qlo, which is the
minimum charge value that we compute the charge PDFs for. This is to prevent
the likelihood from returning nan.
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This commit updates fast_acos() to use an algorithm I found here:
https://web.archive.org/web/20161223122122/http://http.developer.nvidia.com:80/Cg/acos.html
which is faster than using a lookup table.
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After some testing, I realized that the fast_sqrt() function wasn't really
faster than the native sqrt function.
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This commit updates the likelihood to use the multiphoton PCA time instead of
the usual pt time. When looking at the reconstruction of muons in run 10,000 I
noticed that the PMT hit times for the PMTs which had really high charge was
all over the place. There were PMTs that were very close to each other with hit
times differing by ~ 20 ns. I'm still not entirely sure what causes this (is
it some hardware issue with the discriminator or is it a problem with the
charge walk correction which always assumes a single PE?), but the multiphoton
PCA times looked a lot more reasonable.
Eventually I need to look into the ptms variable which is the multiphoton PCA
transit time RMS.
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Previously I was accidentally passing the absolute position of the particle
instead of the distance to the PMT to get_theta0_min().
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