Download First All-Sky Measurement of Muon Flux with IceCube

First All-Sky Measurement of
Muon Flux with IceCube
IceCube REU Summer 2008
Kristin Rosenau
Advisor: Teresa Montaruli
IceCube Neutrino Telescope
 Located at the geographic South
Pole
 Buried beneath roughly 1.5 km of ice,
extending down to 2.5 km.
 Antarctic Muon and Neutrino
Detector Array (AMANDA) was the
proof of concept for IceCube
 4,800 Digital Optical Modules
(DOMs), or photomultiplier tubes,
are inserted into the ice on 80
cables referred to as "strings."
 Each string holds 60 DOMs.
IceCube Neutrino Telescope
 Works on the principle of
Cherenkov Light
 Muons produced by
cosmic rays in the
atmosphere are
background for
astrophysical searches
 Neutrinos cannot be
detected directly
 Neutrinos convert into
muons inside the Earth
 Earth is used as a filter
against background
Project Objective
 Goal: The first all-sky measurement of muon flux
with IceCube.
Muons are a calibration tool for IceCube.
Unprecedented statistics for these events
 Project Steps:
Initial Cuts (weak)
Final Cuts (hard)
Compare IceCube-22 (IC-22) data with Monte Carlo
simulation
Ideal Situation
(Horizon)
(Horizon)
Reality
Useful Variables
 Variables with highest
degrees of correlation to the
angular resolution (which
indicate a quality parameter):
 Sigma Paraboloid
 Direct Length
 Reduced Likelihood
Effect of Cuts
where =efficiency
3º
“Good” events
20º
1º
“Bad” events
1.5º
1º
•Determining cut
parameters based on
optimization
Optimization
Variable
Cut Parameter
Sigma Zen
<.03 radians
Direct Length
>200 m
Reduced Likelihood
<11
Optimization
Misreconstructed
Muons
(Horizon)
Reduction in
misreconstructed muons
Angular Resolution
Before cuts
After cuts
Coincident Muons
quality parameter
Background Suppression
before cuts
after cuts
angular resolution
Single vs. Coincident Muons
Single and coincident muons have
been eliminated past the horizon.
IceCube-22 Data
Minimum Bias Data
Keeps every 200th event
Muon Filtered Data
Keeps all events below 70º because the
neutrinos below the horizon are the focus
IceCube-22 Data
 The initial cut was applied
to the Minimum Bias Data
 The final cut was applied to
the Muon Filtered Data
Results
Results
In the Future
 The muon flux can be used to compare and contrast
IceCube with other detectors
 It will be used extensively in calibration of the IceCube
detector
Desiati P. et al. 2003. Response of AMANDA-II to Cosmic Ray Muons; Universal Academy Press, Inc. 1373-1376
Acknowledgements
A special thanks to the following people for
all the advice and help with this project:
Patrick Berghaus
Teresa Montaruli
Paolo Desiati
Albrecht Karle
IceCube Collaboration
UW-Madison Astrophysics REU Program
NSF