BAIKAL DUMAND[HIGH ENERGY NEUTRINO AND GAMMA-RAY ASTROPHYSICS]

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The Main puropose of our project is to develope the fudamental techniques by which we could realize the extremely high energy neutrino astrophysics in the lake Baikal. In our opinion, the ultimate aim of the extremely high energy neutrino astrophysics is to understand the Universe which could be elucidated by neutrino only. On the other hand, the aim of the high energy neutrino astrophysics whose enery is lower than that of extremely high energy neutrino astrophysics is to understand the Universe by neurtino, reffering to the image of the Universe enlighted by high energy gamma-ray. As you know well, there are four projects on the high energy neutrino astrophysics in the world. Namely, DUMAND (Hawaii), NT-200 (the Baikal), AMANDA (south pole) and NESTOR(the Me diterranean). Among them, only [NT-200] has succeeded in the reconstructions of high energy muon tracks which are absolutely important for thedetection of the high energy cosmic muon-neutrino.There are serious problems to be over … More come in both experiments and the calculations in high energy neutrino astrophysics still now. One of them is the energy determination of muon-neutrino. In this problem, the fluctuation play an important role. We have calculated the relation between the muon energy and the Cherenkov light produced, taking into account the fluctuation effect rigorously.Also, we have examined the behavior of hig energy muon in water, taking into account the fluctuation correctly and have found that the catastrophic energy loss due to the bremsstrahlung play the decisively important role for the energy determination of the muon. As for the high energy gamma-ray astrophysics, we have examined the performances of Russian made photomultiplier which is expected to be improved for the high energy gamma-rsay experiment linked with NT-200.Some techniques have been developed in this project for the extremely high energy neutrino astrophysics. The cross sections for the extremely high energy muon to cause the bremsstrahlung and direct electron pair production have been obtained. The cross section is expected to be utilized the energy determination of the muon in extremaly high energies. Less