First All-Sky Measurement of Muon Flux with IceCube

IceCube REU Summer 2008

Kristin RosenauAdvisor: 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

Reality

Ideal Situation

(Horizon)

(Horizon)

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

1.5º

1º

20º3º1º

“Good” events

“Bad” events

where =efficiency

•Determining cut parameters based on optimization

Optimization Variable

Cut Parameter

Sigma Zen <.03 radians

Direct Length >200 m

Reduced Likelihood <11

Optimization

Misreconstructed Muons

Reduction in misreconstructed muons

(Horizon)

Angular Resolution

Before cuts

After cuts

Coincident Muons

Background Suppression

angular resolution

qual

ity p

aram

eter

before cuts after cuts

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