A precise technique for the determination of some nuclear reaction energies

Abstract
A technique has been developed for the absolute determination of nuclear reaction energies by means of a 180° magnetic spectrometer, in which the effective diameter has been measured against a standard scale, and the magnetic field determined by means of a nuclear resonance apparatus. These two measurements, together with the angle of reaction, were the only precise dimensions required. The spectrometer was used to establish a high-voltage scale by means of elastic scattering of protons. Thus sufficient data could be obtained in a nuclear reaction to determine the Q values which are presented in a separate papers. In order to utilize the experimental data efficiently, it was necessary to investigate quantitatively the line shapes in the spectrometer. An empirical method for correcting observed reaction energies for target deterioration is discussed. To obtain verification of the theoretical line shapes for nearly monoenergetic sources, we have measured the Hρ values for several groups of natural α-particles and have obtained the following results, in kilogauss cm : ThC', 427.07± 0.10; ThC α 0 , 354.34; ThCα x , 355.51; Po, 331.76 ± 0.09.