Comments on atmospheric muon
and neutrino backgrounds
in neutrino telescopes
Use semi-analytic estimates to
display some systematic features of
atmospheric muons and neutrinos
deep underground
Chiba, July 29, 2003
Tom Gaisser
Muons at depth
From report of the Neutrino Facilities Assessment Committee
Chiba, July 29, 2003
Tom Gaisser
Muons at depth
(P. Desiati et al., ICRC2003)
From report of the Neutrino Facilities Assessment Committee
Chiba, July 29, 2003
Tom Gaisser
m energy spectra at depth
See D Chirkin et al. for application
to calibrating Nhit in AMANDA
Chiba, July 29, 2003
Tom Gaisser
Response functions for m at depth
Fraction of multi-m: .08, .05, ..03, .02, .01, .007
--decreases as depth increases
Chiba, July 29, 2003
Tom Gaisser
Muon multipliclity in coincident events
Area--solid-angle ~ 1/3 km2sr
(including angular dependence of EAS trigger)
Chiba, July 29, 2003
Tom Gaisser
Neutrino response
Neutrino energy
Chiba, July 29, 2003
Primary energy / nucleon
Tom Gaisser
K/p bigger for n than for m
Chiba, July 29, 2003
Flavor-dependence of
horizontal/vertical
Tom Gaisser
Compare primary response of
n-induced m to atmospheric m
Response for atmospheric n
Chiba, July 29, 2003
Tom Gaisser
Primary spectrum
Chiba, July 29, 2003
Tom Gaisser
n
muons
Global atmospheric n spectrum
Plot shows sum of
neutrinos + antineutrinos
nm
ne
Solar n
Prompt m
Slope = 3.7
Chiba, July 29, 2003
Tom Gaisser
Slope = 2.7
Summary
• Characteristic Em ~ 200-300 GeV gives tag
for energy calibration of neutrino telescope
• Response functions allow analysis of
uncertainty from primary spectrum
– n-induced muon reponse independent of depth
– response of atmospheric m depends on depth
– <10% multiple muons when triggering on deep
detector, but air shower trigger  multi-mu
Chiba, July 29, 2003
Tom Gaisser