A Student Experiment to Prove the Laws of Conservation of Energy and Momentum for Nuclear Reactions Using a 1.5 MeV Van de Graaff Accelerator

The year 1931 saw the first artificially induced nuclear reaction in the Cavendish Laboratory. The men behind this ground breaking experiment, J.D. Cockcroft and E.T.S. Walton, used a 150 kilovolt accelerator with a screen of zinc sulfide to detect the emitted alpha particles from the ${ }^7$Li (p,$\alpha )\alpha $ reaction. In 1951 the Nobel Prize was awarded in recognition of work that in effect started the nuclear age. The Q value for a nuclear reaction is defined as $\Delta $mc$^2$, where $\Delta $m is the mass converted to energy during the reaction. In order to study the kinematic equations the following reactions were performed: ${ }^7$Li (p,$\alpha )\alpha $, ${ }^6$Li (p,${ }^3$He)$\alpha $, ${ }^{19}$F (p,$\alpha ){ }^{16}$O and ${ }^{11}$B (p,$\alpha ){ }^8$Be. The experiments were carried out with a 1.5 MeV proton beam from a Van de Graaff accelerator. The experimental energies for the reaction products were compared to the theoretical values obtained using the kinematic equations.