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

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

{ 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)

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

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

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

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?

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)

String 21 Geometry 19 m 15 m 77 ns

String 21 Timing ice properties?

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

String 29 Timing

String 30 Geometry

String 30 Timing

String 38 Geometry

String 38 Timing

String 39 Geometry

String 39 Timing

String 40 Geometry

String 40 Timing

String 49 Geometry

String 49 Timing

String 50 Geometry

String 50 Timing

String 59 Geometry

String 59 Timing

Future Work