Proton-Triton Elastic Scattering below 1 MeV

Cross sections for proton-triton elastic scattering have been measured between 163- and 520-keV c.m. energy for a scattering angle of 120° c.m. A hydrogen gas target was bombarded with tritons accelerated by an electrostatic generator. Recoil protons emerging at a laboratory angle of 30° were analyzed with a 16-in. radius, 180° double-focusing magnetic spectrometer. The cross section is 180 mb/sr at 163 keV, rises to a broad maximum of 240 mb/sr near 275 keV, and falls gradually to a value of 207 mb/sr at 520 keV. The standard deviations in the absolute cross sections range from 4 to 9%. The energy region studied here includes the region of excitation in the compound nucleus, ${\mathrm{He}}^4$, in which there has been evidence for a $0^{+}$ excited state. The implications of the present results for the question of the existence of an excited state of ${\mathrm{He}}^4$ will require a theoretical analysis of the data. A search for monopole electron pairs from a $0^{+}$ →$0^{+}$ transition was made with indeterminate results.