Ground-state photoneutron reactions in sup18O

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Phys. Rev. C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.36.1243· OSTI ID:6011981

Jury, J W; Kuo, P C; McNeill, K G; Ross, C K; Weller, H R; Raman, S

Differential cross sections have been measured for the reaction /sup 18/O(..gamma..,n/sub 0/)/sup 17/O over the region of excitation energy from 14 to 26 MeV. The angle-integrated cross section for the ground-state transition reveals that this channel accounts for less than 20% of the total photoneutron cross section in the structured pygmy resonance region (near 14 MeV) and is a small fraction (10--15 %) of the cross section in the region of the giant resonance (near 25 MeV). The values of angular distribution coefficients fitted to the data are consistent with a description of this reaction in which electric dipole excitations dominate the cross section in the pygmy resonance. Narrow regions exist near 15.0, 16.0, and 20.0 MeV where nonzero a/sub 1/ coefficients are observed indicating the absorption of non-E1 radiation. The measured cross section and a/sub 2/ coefficients are compared to a direct-semidirect calculation which gives reasonable agreement and suggests that f-wave neutron emission dominates the ground-state channel and that there is little justification for the introduction of E2 amplitudes other than a pure direct E2 term.

• Research Organization: Department of Physics, Trent University, Peterborough, Ontario, Canada K9J 7B8
• OSTI ID: 6011981
• Journal Information: Phys. Rev. C; (United States), Journal Name: Phys. Rev. C; (United States) Vol. 36:4; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

651320* -- Nuclear Properties & Reactions
A=6-19
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR MOMENTUM
BARYONS
CROSS SECTIONS
DIFFERENTIAL CROSS SECTIONS
E1-TRANSITIONS
E2-TRANSITIONS
ELEMENTARY PARTICLES
ENERGY RANGE
ENERGY SPECTRA
ENERGY-LEVEL TRANSITIONS
EVEN-ODD NUCLEI
FERMIONS
GIANT RESONANCE
HADRONS
ISOSPIN
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
MEV RANGE
MEV RANGE 10-100
MULTIPOLE TRANSITIONS
NEUTRONS
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
NUCLEONS
OXYGEN 17
OXYGEN 18 TARGET
OXYGEN ISOTOPES
PARTICLE MODELS
PARTICLE PROPERTIES
PHOTONEUTRONS
PHOTONUCLEAR REACTIONS
PHOTONUCLEONS
RESONANCE
SHELL MODELS
SINGLE-PARTICLE MODEL
SPECTRA
STABLE ISOTOPES
TARGETS