An electrostatic analyser for the absolute measurement of proton energies and the establishment of fixed points on the high-voltage scale

An electrostatic analyser for measuring the energy of proton beams from an electrostatic generator is described. The energy measurements are absolute and are referred finally to the voltage of thermostatically controlled standard cells. The angle of deflection, 63.2°, was chosen to focus a parallel incident beam on to a fine exit slit. Target currents of over 20¿A were thus obtained with an energy resolution of 1200. The energy of a proton beam producing the lowest strong resonance in the F19(p¿¿)O16 reaction was determined as 874.5±0.9 keV (absolute); the width of the resonance at half maximum yield was 5.0±1.0 keV. Resonances in the Be9(p¿)B10 reaction were found for proton energies of 2.567±0.003 MeV, 1.0837±0.0007 MeV and 989.5±1.4 keV. The widths at half maximum yield of these resonances were 41±3 keV, 3.8±0.3 keV, and 91±5 keV respectively.