Log 20

Justin Vandenbroucke

justinv@hep.stanford.edu

Stanford University

5/30/03

 

This file contains log entries summarizing the results of various small subprojects of the AUTEC study.  Each entry begins with a date, a title, and the names of any relevant programs (Labview .vi files or Matlab .m files – if an extension is not given, they are assumed to be .m files).

 

Note: Higher-resolution versions of the figures are available.  If a log has URL dirname/logLL.html, Figure FF of the log should be at URL dirname/FF.jpg.

 

 

5/30/03

Diamond waveform rejection

PlotDiamondTemplate.m

 

Figure 1

 

Figure 2

 

Figure 3

 

Figure 4

 

Figure 5

 

5/30/03

Successful rejection of all events with aggressive cuts

            By applying all of our cuts together (including three new ones: diamond waveform metric, crossings above threshold, and angle above horizontal after localization), I was able to reject all neutrino candidates.  The cuts were somewhat aggressive (but I don’t think overly so).  I don’t know what the overall neutrino efficiency is but would guess it’s ~1/2.  We should be able to relax some of the cuts and still reject all background with a higher efficiency.  Below are our current strategy and notes for a future, improved strategy.

 

Current cut strategy:

Filter trigger (online)                                            continuous stream -> 1/103 of stream captured

Electronic noise (online)                                       ~2/3 retained -> 25 x 106 single-phone triggers

5-fold coincidence                                                -> 5 x 106 combinations of 3 x 104 singles

For all 5 singles in each combo:                             -> 2 x 103 combinations of 2 x 103 singles

(not all these singles are still in 5-fold coincidence, only 400 are)

Diamond waveform metric < 0.7

20 kHz< Characteristic frequency < 40 kHz

Characteristic number of periods < 4

Threshold <= 0.024

Localization with all 5 TOA’s (4 TDOA’s):              300 combinations

Angle with horizontal < 8 degrees

For all 5, crossings above threshold < 2                   0 combinations

 

Future cut strategy:

Use crossings above threshold earlier (even online?)

Relax cuts on diamond metric, Nikolai parameters (frequency and number of periods), filter thresholod (->

higher neutrino efficiency)

Use spike metric if necessary (with other cuts relaxed)

Use localization metric if necessary (I never used it here; some events were clearly random coincidences

from how large this metric was and from the excess of events at the effective volume boundary)

Return to 4-fold coincidence; achieve higher acceptance?

 

5/30/03

Estimate of our new flux limit