A search for neutrino-induced inverse $\beta$-decay in $^{210}$Bi spectrum

We present results of $^{210}$Bi $\beta$-spectrum analysis. A search for monoenergetic peak around the spectrum endpoint was performed. The presence of such peak would be the evidence of direct observation of inverse $\beta$-decay reaction, which can be caused, in particular, by capture of relic neutrino by the bismuth nucleus. The absence of statistically significant excess of such events allowed for setting of the upper limit on product of relic neutrino flux $\Phi_\nu$ and capture cross-section $\sigma_\nu$: $\sigma_\nu\cdot\Phi_\nu\le 1.4\cdot 10^{-12}$ s$^{-1}$.