T. Kifune

Experimental Study of the Atmospheric Neutrino Flux

Abstract We have observed 277 fully contained events in the KAMIOKANDE detector. The number of electron-like single-prong events is in good agreement with the predictions of a Monte Carlo calculation based on atmospheric neutrino interactions in the detector. On the other hand, the number of muon-like single-prong events is 59±7% (statistical error) of the predicted number of the Monte Carlo calculation. We are unable to explain the data as the result of systematic detector effects or uncertainties in the atmospheric neutrino fluxes.

The acceleration of cosmic-ray protons in the supernova remnant RX J1713.7-3946.

Protons with energies up to ∼1015 eV are the main component of cosmic rays, but evidence for the specific locations where they could have been accelerated to these energies has been lacking. Electrons are known to be accelerated to cosmic-ray energies in supernova remnants, and the shock waves associated with such remnants, when they hit the surrounding interstellar medium, could also provide the energy to accelerate protons. The signature of such a process would be the decay of pions (π0), which are generated when the protons collide with atoms and molecules in an interstellar cloud: pion decay results in γ-rays with a particular spectral-energy distribution. Here we report the observation of cascade showers of optical photons resulting from γ-rays at energies of ∼1012 eV hitting Earths upper atmosphere, in the direction of the supernova remnant RX J1713.7–3946. The spectrum is a good match to that predicted by pion decay, and cannot be explained by other mechanisms.

DISCOVERY OF TEV GAMMA RAYS FROM SN1006: FURTHER EVIDENCE FOR THE SNR ORIGIN OF COSMIC RAYS

This paper reports the first discovery of TeV gamma-ray emission from a supernova remnant made with the CANGAROO 3.8 m Telescope. TeV gamma rays were detected at the sky position and extension coincident with the north-east (NE) rim of shell-type Supernova remnant (SNR) SN1006 (Type Ia). SN1006 has been a most likely candidate for an extended TeV Gamma-ray source, since the clear synchrotron X-ray emission from the rims was recently observed by ASCA (Koyama et al. 1995), which is a strong evidence of the existence of very high energy electrons up to hundreds of TeV in the SNR. The observed TeV gamma-ray flux was

Invariance Violation Extends the Cosmic-Ray Horizon?

(2.4\pm 0.5(statistical) \pm 0.7(systematic)) \times 10^{-12}

Detection of Sub-TeV Gamma Rays from the Galactic Center Direction by CANGAROO-II

cm

Energy Spectrum of Primary Cosmic Rays Between 10**14.5-ev and 10**18-ev

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Detection of Gamma Rays of up to 50 TeV from the Crab Nebula

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Very high energy gamma rays from PSR 1706-44

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Detection of gamma rays around 1 TeV from RX J0852.0-4622 by CANGAROO-II

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Design study of CANGAROO-III, stereoscopic imaging atmospheric Cherenkov telescopes for sub-TeV γ-ray detection

\ge 3.0\pm 0.9