Threshold photoneutron angular distribution and polarization studies of nuclei

Journal Article · Wed Apr 01 04:00:00 EST 1981 · IEEE Trans. Nucl. Sci.; (United States)

DOI:https://doi.org/10.1109/TNS.1981.4331396· OSTI ID:6298529

Holt, R J

The photoneutron method was applied to the study of (i) deuteron photodisintegration, (ii) giant magnetic dipole resonances in heavy nuclei, (iii) mechanism of radiative capture in light nuclei and (iv) isospin splitting of the giant dipole resonance in /sup 60/Ni. These studies were performed with the pulsed bremsstrahlung beam and high-resolution spectrometer available at the Argonne high-current electron linac. A threshold photoneutron polarization method was developed in order to search for the giant M1 resonance in hevy nuclei. A surprisingly small amount of M1 strength was found in /sup 208/Pb. Furthermore, the M1 strength for the 5.08-MeV excitation in /sup 17/O, the best example of a single-particle M1 resonance in nuclei, was found to be strongly quenched. In addition, the /sup 17/O(..gamma..,n/sub 0/)/sup 16/O reaction was found to provide an ideal example of the Lane-Lynn theory of radiative capture. The interplay among the three components of the theory, internal, channel and potential capture, were evident from the data. An electron beam transport system was developed which allows the bremsstrahlung to impinge on the photoneutron target on an axis perpendicular to the usual reaction plane. This system provides an accurate method for the measurement of relative angular distributions in (..gamma..,n) reactions. This system was applied to a high-accuracy measurement of the relative angular distribution for the D(..gamma..,n)H reaction. The question of isospin-splitting of the giant dipole resonance in /sup 60/Ni was studied by using the unique pico-pulse from the accelerator and the newly installed 25-m, neutron flight paths. The results provide clear evidence for the effect of isospin splitting.

• Research Organization: Argonne National Lab., IL
• OSTI ID: 6298529
• Journal Information: IEEE Trans. Nucl. Sci.; (United States), Journal Name: IEEE Trans. Nucl. Sci.; (United States) Vol. 28:2; ISSN IETNA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
COBALT 59 TARGET
DATA
DEUTERIUM TARGET
DIRECT REACTIONS
DISTRIBUTION
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FUNCTIONS
GAMMA SPECTRA
GIANT RESONANCE
HEAVY NUCLEI
INFORMATION
INTERMEDIATE MASS NUCLEI
ISOSPIN
ISOTOPES
KNOCK-OUT REACTIONS
LEAD 208
LEAD 208 TARGET
LEAD ISOTOPES
M1-TRANSITIONS
MULTIPOLE TRANSITIONS
NEUTRON SPECTROSCOPY
NICKEL 60
NICKEL ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUMERICAL DATA
OXYGEN 17 TARGET
PARTICLE PROPERTIES
PHOTONUCLEAR REACTIONS
RESONANCE
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
STRENGTH FUNCTIONS
TARGETS