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

IceTray 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

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?

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

What do the events look like? DOM 23 flashing

What do the events look like? DOM 23 flashing

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

What do the events look like? DOM 23 z position

Up and Down String 21 DOM 12 DOM 23 DOM 32

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

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

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

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

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

Ice Properties

Ice Properties dip from previous graph maximum from previous graph

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

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

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?)