Three-body Photodisintegration Research Articles

Three-body photodisintegration ofHe3

Cross sections for three-body photodisintegration of $sup 3$He are calculated in the electric-dipole approximation. The calculation is performed within the context of exact three-body theory with the two-nucleon interactions represented by s-wave, spin-dependent separable potentials fitted to low-energy nucleon-nucleon scattering data. The photodisintegration amplitude is expressed in terms of the fully-off-shell nucleon plus correlated-pair amplitudes, a method applicable to any weak-process disintegration amplitude. The numerical results indicate: (1) The $sup 3$He($gamma$,n)2p total cross section has a peak value of approximately 1 mb. (2) The neutron spectra for $sup 3$He($gamma$,n)2p and the proton spectra for $sup 3$He($gamma$,p) np peak sharply in the region of the strong p-p final state interaction. (AIP)

Sum-rule photodisintegration cross sections for the three-nucleon system with the Hamada-Johnston potential

A sum-rule calculation of the three-body photodisintegration cross sections ( σ in† and σ b ) is performed using the Hamada-Johnston potential. This is the first calculation of the E1 transition with a realistic potential, and the results show the importance of the tensor force in obtaining agreement with experiment. The contributions of the parity dependent linear LS and quadratic LS forces are negligible. The quantity σ b is closely related to the charge radius of 3H and thus allows an estimation of the Coulomb energy. This estimation gives E C = 0.60 ± 0.03 MeV, which is in accordance with our previous calculation.

Trinucleon three-body photodisintegration

Corrections to the three-body photodisintegration cross section due to (i) the use of an S-state containing a soft core and the inclusion of admixed states of the S′ and D type in the ground state and (ii) final-state interactions between nucleons in relative s-states are calculated. A satisfactory fit to the data is obtained for energies up to the peak cross section.

Trinucleon three-body photodisintegration

Trinucleon three-body photodisintegration

Photodisintegration of the trinucleon system in a separable potential model

Two- and three-body photodisintegration cross sections of 3H and 3He are calculated. The ground state wave function used is an exact solution of the three-body Schrödinger equation with separable potentials of the Yamaguchi type. The final states contain the interactions between nucleon pairs. Results are shown both for the Yamaguchi-Sitenko-Kharchenko set and for the Tabakin set of interaction parameters.

A zero-range treatment of the three-body photodisintegration cross section of 3H and 3He

A zero-range approach is used to construct bound and continuum state wave functions. The total and differential electric dipole photodisintegration cross sections for three-body breakup of 3He and 3H are calculated using these wave functions.

Three-Body Photodisintegration ofHe3

The ${\mathrm{He}}^{3}(\ensuremath{\gamma}, n)2p$ cross section has been measured in 1-MeV steps from threshold to 30 MeV using the National Bureau of Standards betatron and a ${\mathrm{He}}^{4}$ cryostat to produce a 40-${\mathrm{cm}}^{3}$ liquid-${\mathrm{He}}^{3}$ target. The measured cross section shows a broad peak between 14 and 20 MeV with a maximum cross section at about 0.90 mb. The cross section and bremsstrahlung-weighted cross section integrated up to 28 MeV give 12.1\ifmmode\pm\else\textpm\fi{}10% MeV mb and 0.68\ifmmode\pm\else\textpm\fi{}10% mb, respectively. Theoretical calculations of the three-body photodisintegration cross section overestimate the experimental cross section by factors of 3 to 10.

Photodisintegration ofHe3

The 90\ifmmode^\circ\else\textdegree\fi{} photodisintegration cross sections for ${\mathrm{He}}^{3}$ were measured for incident photon energies between 8.5 and 21.5 MeV by detecting proton-deuteron coincidences in CsI(Tl) scintillators immersed in 1 atm of gas. The source of x rays was the bremsstrahlung beam of the University of Illinois 22-MeV betatron. The simultaneous output pulses from the coincidences were displayed on a dual-beam oscilloscope and photographed. The particle energies were determined by pulse-height measurement, and electrons were rejected by pulse-shape analysis. The peak cross section for the ${\mathrm{He}}^{3}(\ensuremath{\gamma}, p)d$ reaction, which is very sensitive to the nuclear size, occurs at 10.8\ifmmode\pm\else\textpm\fi{}0.3 MeV and equals 0.092\ifmmode\pm\else\textpm\fi{}0.004 mb/sr. Gaussian ground-state wave functions for ${\mathrm{He}}^{3}$ fail to predict the shape of the cross-section curve. The modified exponential wave function of Gunn and Irving gives a good fit for a root-mean-square nuclear radius of 1.94 F (corresponding to a charge radius of 2.1 F). The ${\mathrm{He}}^{3}$ charge form factor calculated with this wave function agrees very well with the electron scattering measurements of Collard and Hofstadter for small momentum transfers $q$ and deviates by 20% only at ${q}^{2}=5$ ${\mathrm{F}}^{\ensuremath{-}2}$. Also, some information was acquired about the competing three-body photodisintegration process by detecting proton-proton coincidences in the cases where the angle between the two outgoing protons was near either 90 or 180\ifmmode^\circ\else\textdegree\fi{}.