Electrostatic Deflection Studies of Alpha-Particles; the Alphas fromLi6(p,α)He3

A technique is described for studying nuclear reactions in which short range alpha-particles are produced with a yield that is too small for the direct application of the electrostatic deflector. In preliminary experiments a strong polonium source is used to supply alpha-particles to the deflector, and a group of these alphas, homogeneous in energy, passes through the deflector and enters a variable pressure absorption cell and ionization chamber. Cut-off pressures determined for various alpha-particle energies result in a calibrated cell which can then be used to determine the alpha-particle energies in nuclear disintegrations. Application of this method to ${\mathrm{Li}}^6(p,\alpha ){\mathrm{He}}^3$ results in a $Q$ value of 3.94±0.08 Mev. The calibration, extending in alpha-particle energy from 1 to 1.8 Mev, is also used to determine the slope of the range energy curve. The average value of the slope found for this region is 200 kv per mm range.