Search for muon catalyzed $d^{3}He$ fusion

Abstract

This report presents the results of an experiment aimed at observation of the muon catalyzed ${}^{3}Hed$ fusion reaction ${}^{3}He+\mu d{\to }^{3}He\mu d{\to }^{4}He(3.66MeV)+p(14.64MeV)+\mu$ which might occur after a negative muon stop in the $D_2{+}^{3}He$ gas mixture. The basic element of the experimental setup is a Time Projection Chamber (TPC) which can detect the incoming muons and the products of the fusion reaction. The TPC operated with the $D_2{+}^{3}He(5$ gas mixture at $31K$ temperature. About $10^8$ ${}^{3}He\mu d$ molecules were produced with only 2 registered candidates for the muon catalyzed ${}^{3}Hed$ fusion with the expected background $N_{bg}=2.2\pm 0.3$ events. This gives an upper limit for the probability of the fusion decay of the ${}^{3}He\mu d$ molecule $P_F{(}^{3}He\mu d)\le 1.1\cdot 10^{-7}$ at 90% C.L. Also presented are the measured formation rate of the ${}^{3}He\mu d$ molecule ${\lambda }_{d3He}=192(3)\cdot 10^6{s}^{-1}$ and the probability of the fast muon transfer from the excited to the ground state of the $\mu d$ atom $q_{1S}=0.80(3)$.

13 pages, 8 figures