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Brightness and Calibration of String 21 Flashers in AMANDA Collaboration

This study investigates whether the String 21 flashers are sufficiently bright to trigger events in the AMANDA detector. Preliminary results indicate that up to 60% of flasher events successfully trigger AMANDA, with 40-50% of these events being string-triggered. Detailed analysis of flashing occurrences across various DOMs shows promising results for measuring ice properties and improving calibration through unified trigger mechanisms. The findings could enhance future ice property measurements and simulations within the AMANDA framework.

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Brightness and Calibration of String 21 Flashers in AMANDA Collaboration

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  1. String 21 Flashers and AMANDA Michelangelo D’Agostino UC Berkeley London Collaboration Meeting

  2. Thanks • Dave Hardtke: for doing the first work on this • Kurt: for being the ice guru • John Pretz: for writing his wonderful, bugless merging module for the rest of us to use IceTray

  3. Outline • Are the String 21 flashers bright enough to be seen by AMANDA? • What do these events look like? • Can such flasher events be used for any calibration or ice property measurements?

  4. closest AMANDA strings The Verdict: • Yes! • up to 60% of flashes trigger AMANDA • Roughly 40 to 50% of the AMANDA events were string- triggered

  5. What do the events look like? DOM 23 flashing

  6. What do the events look like? DOM 23 flashing

  7. Stuck String What do the events look like? 16 10 9

  8. What do the events look like? DOM 23 z position

  9. DOM 32 DOM 12 DOM 23 Up and Down String 21

  10. Analysis Details • in July, flasher runs were taken for all DOM’s on string 21 • 10 Hz, full brightness, all 12 LED’s • run monolith offline, requiring a simple multiplicity of 10 string 21 hits in a 5000 ns window

  11. Analysis Details • use John’s Icetray merging module to look for AMANDA triggers with -20 s < t < -5 s of a String 21 trigger • filter out muons (about 1/4 of events): require that the flashing DOM be present in the event and that ATWD channel 3 has a digitized current pulse

  12. what’s going on here? DOM 16 Up and Down String 21 Ryan’s dustlogger data for String 21 DOM 23

  13. Ice Properties: Fluence Analysis • from Poissonian statistics, the average number of received photons in the diffusive regime is given by <N>=-log[P(0)], where P(0) is the probability that the receiver is not hit • 1/λ, where λ is the propagation length, is given by the slope of log[<N>d] vs. d, where d is distance from the light source

  14. Ice Properties DOM 16 flashing 3 closest strings restrict z to +-5 m of the flashing DOM to probe a narrower ice layer corresponds to a λ of 45.3 m +-11.8 m photons all the way to ~400 m

  15. Ice Properties

  16. maximum from previous graph dip from previous graph Ice Properties

  17. Ice Properties • we have a biased sample though, since AMANDA had to be triggered to see the OM hits; the data is L1 filtered as well • P(0) is an overestimate <N> is an underestimate that varies with distance • thus, these are upper limits on the propagation lengths • flasher variability is more likely the culprit for the suspicious dip (cf. Chris Wendt’s talk); longer width runs are needed to tell

  18. Conclusions • the flashers are pretty damn bright • ice properties have been measured over a greater horizontal distance and give reasonable agreement • since flashers should be seen in ~9 IceCube strings, such a method will be much more useful in the future for measuring local ice properties, especially with a unified trigger system

  19. Conclusions • flasher coincidences might also be useful in AMANDA simulation—a simulation capable of reproducing the depth variation in this simple flasher system would surely have a better handle on systematics (COGz?)

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