Correlated neutron-proton pairs from the photodisintegration of oxygen

Angular distributions of protons from bremsstrahlung of maximum energy 400 MeV incident on elements between lithium and gold

“…To lose its excitation energy, it reacts with a second nucleon and conservation of momentum alone is sufficient to lead to the emission of the two nucleons in opposite directions. In this description of the process, the interaction of the two nucleons occurs in the final rather than in the initial state, so that the study of such processes should not give useful information about possible initial-state correlations such as are assumed by Levinger. When started, the present investigation was intended only to be a preliminary study to pave the way for a subsequent, more detailed investigation of n-p coincidences, somewhat along the lines of the measurements described by Garvey et al [4]. However, it became obvious that existing data on photo-proton emission were grossly inadequate, partly because of large discrepancies between results from different laboratories and partly because of the technical advances of the last few years.…”

“…While there has been some discussion in the literature about various aspects of the measurements, it seems to be possible to infer that most high-energy photo-protons from nuclei are emitted in coincidence with high-energy neutrons. This deduction, which is of importance for the subsequent analysis of our experimental results, is based on three separate points: First, Odian et al [9], on the basis of experimental studies of n-p coincidences for a wide range of nuclei, concluded that most high-energy photo-protons were in coincidence with neutrons emitted in an angular region consistent with deuteron-type kinematics, a conclusion which should not be seriously affected by the criticism of Garvey et al [4]. Second, the reported values of L obtained from measurements on neutrons and protons separately agree, to about the above accuracy, with results from n-p coincidences.…”

“…No measurements of photo-protons from oxygen are known to us, although there have been two studies of n-p coincidences [4,8]. In both cases, the target used has been, as here, in the form of a thin-walled container filled with distilled water.…”

Photoproduction of high-energy neutrons in thick targets by electrons in the energy range 150 to 270 MeV

“…The results of the investigation of the nuclear photoeffect, which have been described in several publications [4][5][6][7], point out that at photon energies above 150 MeV the (~, rip) process is the dominant absorption process and that in this region the experimental data can be satisfactorily described by the quasi-deuteron model originally proposed by Levinger [8] and improved by other authors [9][10][11].…”

Dose Measurements of Bremsstrahlung-Produced Neutrons at the Advanced Photon Source

“…L is the quasi-deuteron constant which is given as 6.4 by Levinger [7], though measurements [6,8] to determine this value produced contradictory results. At lower photon energies (< 100 MeV), Equation 2 is expected to overestimate the nuclear cross section.…”