Studies of the giant resonances of /sup 20/Ne and /sup 90/Zr with polarized proton capture

Thesis/Dissertation · Mon Dec 31 23:00:00 EST 1979

OSTI ID:5229319

Kurjan, P M

Polarized and unpolarized angular distributions of the /sup 19/F(polarized p,..gamma../sub 0/)/sup 20/Ne and /sup 19/F(polarized p,..gamma../sub 1/)/sup 20/Ne reactions were measured in small steps at energies from E/sub x/ = 16.1 to 23.0 MeV. This range encompasses the region of the giant dipole resonance (GDR) built upon the ground state, in which very pronounced intermediate structure has been previously reported. The use of a polarized proton beam enabled solutions for the E1 and E2 T-matrix elements for the ground state reaction to be extracted. The intermediate structure in the cross section is found to be due primarily to the /sup 1/P E1 partial wave amplitude, although the /sup 3/P (spin flip) amplitude also resonates with the cross section. The E2 partial wave amplitudes are found to be rather constant over the range of the GDR. The total measured ground state E2 cross section exhausts 40 to 50 percent of the isoscalar E2 sum rule. The E1 cross section in the /sup 19/F(polarized p,..gamma../sub 0/)/sup 20/Ne reaction can be fitted to a series of nearly isolated Breit-Wigner resonances. Polarized and unpolarized angular distributions of the /sup 89/Y(polarized p,..gamma../sub 0/)/sup 90/Zr reaction were measured in small steps at energies from E/sub x/ = 10.4 to 24.6 MeV, with particular attention paid to the Isobaric Analogue Resonances (IAR's) at E/sub x/ = 14.4 and 16.3 MeV. Solutions were extracted for the E1 T-matrix elements. The E/sub x/ = 14.4 MeV IAR is found to be predominantly s-wave in character, while the E/sub x/ = 16.3 MeV IAR is comprised of approximately equal contributions from s-wave and d-wave incident proton amplitudes. The data are in agreement with recent suggestions that a statistical reaction mechanism dominates below the GDR, while a direct-semidirect reaction mechanism is dominant at and above the GDR.

• Research Organization: Stanford Univ., CA (USA)
• OSTI ID: 5229319
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR DISTRIBUTION
BARYON REACTIONS
BEAMS
CAPTURE
CHARGED-PARTICLE REACTIONS
DATA
DISTRIBUTION
E1-TRANSITIONS
E2-TRANSITIONS
ENERGY-LEVEL TRANSITIONS
EVEN-EVEN NUCLEI
EXPERIMENTAL DATA
FLUORINE 19 TARGET
GIANT RESONANCE
HADRON REACTIONS
INFORMATION
INTERMEDIATE MASS NUCLEI
INTERMEDIATE STRUCTURE
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LIGHT NUCLEI
MULTIPOLE TRANSITIONS
NEON 20
NEON ISOTOPES
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
NUMERICAL DATA
POLARIZED BEAMS
PROTON REACTIONS
RADIOISOTOPES
RESONANCE
STABLE ISOTOPES
TARGETS
YTTRIUM 89 TARGET
ZIRCONIUM 90
ZIRCONIUM ISOTOPES