Search for $^{73}$Rb and Investigation of Nuclear Decay Modes Near the Z=N Line in the Border Region of the Astrophysical RP-Process Path

% IS351 \\ \\ Following a test experiment on the production rates of $^{73}$Rb and $^{74}$Rb and the negative result concerning the existence of $^{73}$Rb, we have studied the mirror $\beta$- decay of $^{71}$Kr and observed for the first time the $\beta$- decay of $^{70}$Kr. The $\beta$- decay study of $^{71}$Kr extends the systematics of mirror decays to an upper $fp$-shell. The observation of the $\beta$- decay of $^{70}$Kr resulted in the first half-life measurement of this nucleus. Our result disagrees with the value used in the recent rp-process calculations. The new half-life value may increase the effective two proton capture rate of $^{68}$Se by a factor of 6.5.