Chemical Reactions of Li and CaH at 1 Kelvin

Using cryogenic helium buffer-gas cooling, we have prepared dense samples of atomic lithium and molecular calcium monohydride at temperatures as low as 1 Kelvin. We have measured the Li~+~CaH~$\rightarrow$~LiH~+~Ca chemical reaction, observed in both the accelerated disappearance of CaH and in the appearance of the LiH molecule. For unpolarized reactants, we have measured a reaction rate coefficient of $3.6\times10^{-10}$~cm$^3$~s$^{-1}$, with an uncertainty of a factor of 2. The methods of reaction rate measurement and detection of LiH molecules will be presented.