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PRODID:UW-Madison-Physics-Events
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SEQUENCE:1
UID:UW-Physics-Event-7806
DTSTART:20220825T190000Z
DTEND:20220825T230000Z
DTSTAMP:20260414T113424Z
LAST-MODIFIED:20220728T185609Z
LOCATION:https://uwmadison.zoom.us/j/97268699602?pwd=ZTc1SEYyWkgzSFdMN
 XVzdFhCU3k0Zz09
SUMMARY:A Few New Techniques for Probing IceCube Data and a Search for
  High Energy Atmospheric Neutrinos\, Thesis Defense\, Bunheng Ty\, Phy
 sics PhD Graduate Student
DESCRIPTION:The idea of characterizing an IceCube event by its locatio
 n and magnitude of maximum photon density is proven useful. A complete
  set of new filter tools built around this idea is successfully develo
 ped and used to detect high-energy neutrino interactions inside IceCub
 e. The two key features to search for are: a highly localized deposit 
 of photoelectrons\, and a lack of a veto track leading up to it. The f
 irst is achieved reliably by counting photoelectrons making up the mos
 t photon-dense region of the event. The second is achieved with moving
  cylinders (160 m radius\, 240 m half-height\, 0.3 m/ns speed)\, one a
 t each possible direction from the sky\, collecting any DOM forming a 
 muon track pattern with the region. In addition to the traditional tru
 e starting events\, this new approach allows\, for the first time\, a 
 direct search for the self-veto events of the atmospheric neutrinos. T
 he no-veto condition is loosened to allow up to a very small veto\, ju
 st enough to be still outside the region of the atmopsheric muon backg
 round. The final selection consists of 23 events\, one of which is a s
 elf-veto event of 134 TeV Millipede reconstructed energy. This data\, 
 though limited\, shows a measurable contribution of the atmospheric co
 mponent to the neutrino flux at the high energies. A lower bound estim
 ate is given for the atmospheric contribution to IceCube’s HESE samp
 le to be at least at the level of 1 percent.
URL:https://www.physics.wisc.edu/events/?id=7806
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