1. Geometry and Timing Verification with Flashers
Michelangelo D’Agostino
UC Berkeley
Baton Rouge Collaboration Meeting
April 9, 2006

2. Outline method for obtaining timing and geometry from flashers
specifics of the available data
first results from 9 string IceCube

3. { Method for each DOM, flash all 12 LED’s at full brightness
look at the first photons seen by the module just above that DOM (the target)
the mean of the first hit distribution gives an indication of the spacing
the width of the first hit distribution gives an indication of the timing resolution {
17 m (usually)

4. Method Specifics waveforms in the target DOM have hundreds of PE’s
use Dima’s Feature Extractor to get the leading edge of the waveform
feature-extracted leading edge

5. Method Specifics
also need to obtain the time the flasher went off to do absolute geometry and timing
current pulse into the LED’s is digitized and sent up in ATWD channel 3
get the leading edge time of this current pulse
the algorithm for doing this was the source of the discrepancy between the Fat Reader and standard IceTray analyses; fixed now
the module that does all the analysis and outputs histograms and ntuples is called flasher-timing in the IceVer meta-project

6. Method Specifics
Leading Edge Times
leading edge distributions are very well fit by Gaussians
Time [ns]

7. Errors and Offsets each leading edge distribution has ~4000 entries
the errors on the mean as reported by the fitter are typically ~.01 ns
means are offset from the direct travel time
a systematic of the Feature Extraction or the flash time extraction? delay between digitized current pulse and the actual flash
hole ice?

8. Available Data runs are tagged INITVER
flasher is run at full brightness with pulse width 20 ns at 19 Hz
data for all 9 strings processed (not all the DOM’s on all of the strings yet)

9. String 21 Geometry
19 m
15 m
77 ns

10. String 21 Timing
ice properties?

11. String 29 Geometry
16 m, 18 m spacing alteration clearly visible!!

12. String 29 Timing

13. String 30 Geometry

14. String 30 Timing

15. String 38 Geometry

16. String 38 Timing

17. String 39 Geometry

18. String 39 Timing

19. String 40 Geometry

20. String 40 Timing

21. String 49 Geometry

22. String 49 Timing

23. String 50 Geometry

24. String 50 Timing

25. String 59 Geometry

26. String 59 Timing

27. Future Work