At room temperature, particle energy is 0.025eV. Neutron capture reaction has big cross section when neutron is in room temperature. Theoretically, so does an electron. At 0.025eV, the electron velocity should be only 93.78km/s. Unfortunately almost no way to cool down an free electron to so low velocity, even an outermost orbital electron of atom runs at least 1000km/s above, e.g. 2190km/s for hydrogen electron. In absolute 0K temperature, do the atom orbital electrons no longer move and become standstill?