Page0002, Selecting the stopping muons

  • First of all the Data muon fits are done by onsite-lowe group's realtime muboy fitter. (Eric Blaufuss and BKKim). I took their ``vector files'' which are some kind of zebra nonsense and stripped out just what I needed and saved it as gzipped text-ntuples. The code and info on this is in my repository in the work/stopper directory.

  • Here are some histograms from muboy run on Run 3033, which is to be the canonical data run.

    This shows the reconstructed lengths from muboy. Ignore the gaps, they are due to beating between the histogram bins and the a step size used in muboy.

    This shows the Goodness of Fit that muboy gives. To get a pure sample of well fit stoppers I will cut at 0.5. This value is in keeping with the suggestions of Svoboda's in ``how-muboy-works.txt'' in the src/fit directory of SK repository.

  • The conversion from mbvec.003033.stopper.gz to track input file is done with work/stopper/mbvec2track in my repository. In it the GOF cut is applied to generate the initial test MC also a short length (< 1m) tracks are also killed. I simulate the pid of the muons by using 57.8% antimuons and the rest muons as per John Flanagan's mods to src/usmc/kinematics/kinem/Stopping_Muons.c.

    Mon Jan 25 12:40:02 1999

  • The stopper MC finished over the weekend. I am a little confused about the number of events. The track messages seems to say there are 5288 events, the kin file has 6982 events and eventcount (work/utils, my repo) gives 8295 events. Of course eventcount gives right answer and the kin number is only muons, not dke's. So I guess I just don't understand track's messages. No big deal, I think. The job ran in 37.5 hours and generated ~1/2 GB using -R=1 option to track (don't save every little track)

    Tue Jan 26 14:44:47 1999

  • When running muboyT on this file it fails with bad data, this means that track did die midway. I'll re-generate it.

  • Next I will strip out the data events on to disk. I use the same mbvec2track but just print out run/sub/event and use check_eventT to split them out.

  • Dean fixed the big disk today. Tomorrow Toseef should start to continue highe reduction

    Wed Jan 27 12:03:52 1999

  • Stripping out events crashed (segfault) in the middle. It apears to have happened at the end of the first DLT. Last event found is 3033/098/588038. DLT 185's last event is 3033/098/588242. DLT 186's first event is the next event. There are 827522 events total in 3033. There are 4897 stoppers on DLT185 and 2085 on DLT186 so all are accounted for.

    Wed Jan 27 20:27:59 1999

  • Now working on forming the QxL vs L histograms. One thing that really troubled me the first time I tried this was whether or not to do an intime_long_cut. Well, looking closer shows that this cut will kill a lot of PMTs which have substantial charge but early time due to getting hit first with scattered light. Since I am doing a geometry cut I basically don't have to worry about (out of cone) scattered light so it is a silly cut.

  • Doing just simple histogramming of q*l vs. l gives 67.8 m attenution length. Previously we were using about 75 m for this run. I next need to try to do the statistics of q*l correctly and see how this effects the atten length.

  • The MC stoppers should be done tomorrow. With these I can see what length I get in (MC) water where I can check what length I must use to get flat detector response with MC electrons.

    Fri Jan 29 12:47:53 1999

  • Here are histograms from the USMC stoppers equivelent to the ones for run 3033, above.

    They are fairly similar. The GOF for USMC muons seems shifted downward. The difference in number of events between USMC and data are due to the fact that the USMC events are not really exactly like the data events. Eg. some DATA corner clippers which were poorly fit may turn into real looking stoppers or other event class and be fit differently by Muboy.

    It also appears that there are 2 components to the GOF, a wider lower one which doesn't shift between data and MC and the higher peak which does. I am not sure what this is due to as the definition of GOF is burried in Muboy Svoboda-Fortran.

    In the next page I'll start makeing some attenution plot histograms.
    Last modified: Fri Jan 29 13:02:50 EST 1999