The Kamiokande-ll Solar Neutrino Detector

The properties of the K-II detector relevant to the detection of solar neutrinos are given in Table IV. The resolutions in energy, position, and angle in Table IV 

FIGURE 3 Schematic drawing of the Kamiokande-ii detector in the Kamioka Mine in Japan, showing the iocation of the water purification system, anticounter, and eiectronics hut. 

For the low energy electrons produced by solar neutrino interactions, there are backgrounds arising from natural radioactivity, primarily radon dissolved in the detector water, from gamma-rays emitted by radioactive elements in the rock of the cavity housing the detector, and from the beta-decays of the muon-induced spallation nuclei in the water. 

FIGURE 4 Plot of the cosine of the angle between the electron direction and a radius vector from the sun, showing the signal from the sun plus an isotropic background. This plot is for 9.3 MeV and the time period is January 1987 through April 1990, a total of 1040 live detector days. 

The intensity of the observed signal relative to the standard solar model value, denoted by Data/SSM, was obtained directly from the data in Fig. 4 and was Data/SSM = 0.46 0.05 (stat.) 0.06 (syst.), where again the SSM referred to the calculation of Bahcall and Ulrich. If the SSM calculation of Turck Qiieze et al. was used as the basis of comparison, the result was Data/SSM = 0.70 0.08 (stat.) 0.09 (syst). 

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