1. University of Wisconsin-Madison
The Angular Distribution of Atmospheric Muons in the AMANDA detector at a depth of 1730m
Karen R. Bland
Summer REU 2002
University of Wisconsin-Madison
Madison, WI

2. Overview Introduction to AMANDA Atmospheric muons Analysis Results
Some conclusions
Future studies

3. Antarctic Muon and Neutrino Detector Array

4. Atmospheric Muons Produced by cosmic rays hitting atmosphere
Background to neutrino analysis

5. Analysis Monte Carlo (MC) Same analysis is performed on MC and data:
Simulation codes: Corsika, Corama, MMC, Amasim
Data
AMANDA-II (year 2000) data
~ 13,000 sec of lifetime (3.5 hrs)
Same analysis is performed on MC and data:
Hit cleaning
Filtering
Quality cuts

6. Quality Cuts Optimizing Removing mis-reconstructed events
Angular resolution
Data/MC response
Stability

7. Cuts (cont’d) Cuts: Passing rates: MC: 62.5% Data: 56.0%
Length of direct hits >120 m
Track smoothness between –0.26 and +0.26
The time-likelihood fit reconstruction < 7.8
Passing rates:
MC: 62.5%
Data: 56.0%

8. Unfolding the detector dataMC
true zenith angle
reconstructed zenith angle
Data
reconstructed zenith angle

9. Results: Angular Distribution
Angular Distribution of Downgoing Muons at 1730 m
Angular Distribution of Downgoing Muons at 1730 m
S. Klimushin curve
Data fit – 85 %
MC fit – 68 %
S.I. Sinegovsky curve
Data fit – 73 %
MC fit – 59 %

10. Results: Angular Distribution / Depth-Intensity
Slant Depth Intensity of Down-going Muons
Angular Distribution of Downgoing Muons at 1730 m

11. Results: MC-Data Response / Effective Area

12. Some conclusions Atmospheric muon flux in AMANDA-II
MC-data deviation: ~ 7.5%
There is a systematic effect around 30 degrees from vertical
Horizontal resolution is still poor

13. Other things to look at…
Other ice models
Different depths
Different times of the year
Energy threshold dependence
Vertical depth intensity
Comparisons with other groups

14. Acknowledgments Dr. Paolo Desiati Dr. Albrecht Karle
The UW-Madison AMANDA group
The AMANDA collaboration
Dr. Bob Benjamin
The astrophysics REU group
National Science Foundation

16. Dependence on energy: MC, E = 50 GeV Data, E = 50 GeV MC, E = 25 GeV

17. AMANDA and Cherenkov light