The energy of gamma rays from the reaction H² (p,γ)He³ has been measured as a function of incident proton energy in the range of proton energies from 1 to 2 Mev. The results were consistent with the assumption that the He³ is left in the ground state. The Doppler shift in gamma ray energy was measured for incident protons of energies 1 Mev. and 1.7 Mev. and was found to be consistent with the value calculated assuming that the He³ was not slowed down before emission of the gamma ray. This puts an upper limit on the lifetime of the intermediate state of 2 x 10⁻¹² sec. The angular distribution of gamma rays at an incident proton energy of 1.75 Mev. was of the form sin²θ + (.025 ± .007), and at incident proton energy of 1.00 Mev. was of the form sin²θ + (.043 ± .008). The excitation function, over a range of incident proton energies from 0.25 to 1.85 Mev., is fitted by a function of the form AEp⁰•⁶⁵. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Pulsed magnetic resonance studies are reported for a gas of hydrogen atoms at densities of 3-10¹³ X 10 cm⁻³ and temperatures of 4.2-77 K. The gas was produced by dissociation in a room temperature R.F. discharge, and piped through glass tubing into the cryogenic apparatus for study. The magnetic resonance transition observed is between the two lowest hyper-fine levels of the 1s atom in a magnetic field of 6481 Gauss where this splitting has its minimum value of about 765.5 MHZ. At 77 K, spin-exchange broadening of the resonance is observed. By varying the number density of hydrogen atoms, the ratio of spin-exchange broadening to atomic hydrogen density is obtained, and from this ratio the spin-exchange cross section for this transition is calculated. The cross section obtained is 60% of the theoretical value. At liquid helium temperatures, the spin-exchange cross section is shown to be at least 15 times smaller than that at liquid nitrogen temperatures, as. predicted by theory. He⁴ and H₂ buffer gases . are used to limit the diffusion broadening of the resonance, allowing the observation of small frequency shifts of the free induction signal. A model is proposed in which interactions of the hydrogen atoms with the flow tube walls cause these shifts. From the diffusion broadening of the resonance, the diffusion cross sections for H in He⁴ at 4.2 K and H in H₂ at 5-9 K are inferred to be 500 Ų and 250 Ų respectively. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

By using a pair of large Nal spectrometers in a coincidence configuration we have observed the charge exchange of stopped π⁻ in deuterium π⁻ + d → 2n + π°. We have measured the branching ratio of this reaction [equation omitted] and find R = (1.45 ± 0.19) x 10⁻⁴. This measurement is the first observation of pion charge exchange at rest in deuterium and represents an increase in sensitivity of a factor of 40 over previous measurements. The measured value of R agrees well with the recent theoretical result of Beder(1.39 x 10⁻⁴ ≤ R ≤ 1.59 x 10⁻⁴). / Science, Faculty of / Physics and Astronomy, Department of / Graduate

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