Cosmic-ray muon spectrum up to 20 TeV at 89° zenith angle

Abstract

The 800-ton cosmic-ray spectrograph (MUTRON) has been used to measure the sea-level energy spectrum of cosmic-ray muons arriving from 86" to 90" zenith angles in the momentum region of 100-20000 GeV/c. The measured muon energy spectrum can be interpreted by using a cosmic-ray primary spectrum of (1.80 ~m -~s -' s r -' G e~-' )~-~~~~d~ (E in GeV) and a scaling model incorporating an increasing interaction cross section for meson production in hadron-hadron interaction. The muon charge ratio at energies up to 15 TeV in the same zenith-angle range has been measured. It shows a small enhancement with increasing energy. By combining both results we may conclude that the cosmic-ray primary particle composition stays the same up to about 100 TeV as that obtained by direct measurements in the energy range below 1 TeV.

Development of the very long-range cosmic-ray muon radiographic imaging technique to explore the internal structure of an erupting volcano, Shinmoe-dake, Japan

“…For instance, while the integrated vertical muon flux (0 • from zenith) is 7 × 10 −3 and 5 × 10 −8 cm −2 sr −1 s −1 above 1 GeV and 1 TeV, respectively (Beringer et al, 2012), the horizontal flux (85 • from zenith) is 1 × 10 −4 and 1.6 × 10 −7 cm −2 sr −1 s −1 above 1 GeV and 1 TeV, respectively (Allkofer et al, 1985). For the purpose of interpolating the measured flux, several groups have formulated approximate equations of the muon energy spectrum as a function of energy and zenith angle (e.g., Gaisser, 2002;Matsuno et al, 1984;Smith and Duller, 1959). However, the systematic difference between them ranges from 10 to 100 % (Lesparre et al, 2010).…”

Experimental study of source of background noise in muon radiography using emulsion film detectors

“…Their energy and angular distribution reflect a convolution of their production spectrum, energy loss in the atmosphere and decay. The energy spectra of nearly horizontal muons were investigated in detail in the MUTRON (Matsuno et al, 1984) and DEIS (Allkofer et al, 1985) experiments in the 1980s. In this study, we use the analytic formula for describing the muon energy spectrum developed by Matsuno et al (1984).…”

“…The energy spectra of nearly horizontal muons were investigated in detail in the MUTRON (Matsuno et al, 1984) and DEIS (Allkofer et al, 1985) experiments in the 1980s. In this study, we use the analytic formula for describing the muon energy spectrum developed by Matsuno et al (1984). Although the formula does not take into account the rigidity cutoff due to the geomagnetism of the Earth, or the variation of solar activity, these effects affect the muon flux only in the gigaelectronvolt range, and the variation is only 10 %.…”

Towards a muon radiography of the Puy de Dôme

“…The simulation of the atmospheric muon flux relies both on measurements (Matsuno et al, 1984) and theoretical assumptions (Parente et al, 1995). The propagation of muons through rock is handled with the dedicated propagation code MMC (Chirkin and Rhode, 2004), developed for large-scale neutrino detectors.…”

“…Hence, muon imaging could locate and characterise in terms of size, depth and shape, magma reservoirs, volcanic conduits and hydrothermal systems, particularly when combined with other techniques used in volcanology, such as seismic, electrical and electromagnetic tomography and satellite interferometry. However, HE atmospheric muons are scarce, with fluxes of ∼ 100 m −2 deg −1 day −1 close to the horizontal (Matsuno et al, 1984). Therefore, accurate measurements require timescales of ∼ 1 month/(L/1 m) 2 , where L 2 is the area of the muon collection plane.…”