Isovector giant quadrupole resonance observed in sup 30 Si( rvec p ,. gamma. ) sup 31 P

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Physical Review, C (Nuclear Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevC.43.223· OSTI ID:6254502

Feldman, G; Kramer, L H; Weller, H R ^[1]; Hayward, E; Dodge, W R ^[2]

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1. Duke University, Durham, North Carolina (USA) Triangle Universities Nuclear Laboratory, Durham, North Carolina (USA)
2. National Institute of Standards and Technology, Gaithersburg, Maryland (USA)

The {sup 30}Si({ital {rvec p}},{gamma}){sup 31}P reaction has been studied in the proton energy range {ital E}{sub {ital p}}=20--36 MeV. Angular distributions of the cross section and the analyzing power have been measured for {gamma}-ray transitions to the ground state and the first excited state of {sup 31}P over the angular range 37.5{degree}--145{degree} at {ital E}{sub {ital p}}=25.5 MeV. Legendre polynomial fits to both observables yield nonzero coefficients of order {ital k}=3,4, suggesting the interference of {ital E}2 radiation with the dominant {ital E}1 radiation. A transition-matrix-element analysis of the data indicates that {similar to}26% of the {gamma}{sub 1} cross section at this energy arises from {ital E}2 radiation, whereas only 10% of the {gamma}{sub 0} cross section can be attributed to {ital E}2 radiation. Direct-semidirect calculations give a direct {ital E}2 component of {similar to}7% for both channels, suggesting significant excess {ital E}2 strength in the {gamma}{sub 1} channel at this energy. The energy dependence of the 90{degree} analyzing power for {gamma}{sub 1} shows a resonance structure near {ital E}{sub {ital p}}=34 MeV which can be reproduced by a direct-semidirect calculation including an {ital E}2 resonance at {ital E}{sub GQR}=38.6 MeV with a width of {Gamma}{sub GQR}=5.0 MeV and a strength of 50% of the isovector {ital E}2 energy-weighted sum rule. The current results thus provide strong evidence for collective {ital E}2 strength roughly at the expected peak of the isovector giant quadrupole resonance built on the first excited state of {sup 31}P.

• DOE Contract Number: AC05-76ER01067
• OSTI ID: 6254502
• Journal Information: Physical Review, C (Nuclear Physics); (USA), Journal Name: Physical Review, C (Nuclear Physics); (USA) Vol. 43:1; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

Related Subjects

651420* -- Nuclear Properties & Reactions
A=20-38
Experimental
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ANALYZING POWER
ANGULAR DISTRIBUTION
BARYON REACTIONS
BEAMS
CAPTURE
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
CYCLIC ACCELERATORS
CYCLOTRONS
DISTRIBUTION
E1-TRANSITIONS
E2-TRANSITIONS
ELECTROMAGNETIC RADIATION
ENERGY DEPENDENCE
ENERGY LEVELS
ENERGY RANGE
ENERGY-LEVEL TRANSITIONS
EQUATIONS
GAMMA RADIATION
GIANT RESONANCE
HADRON REACTIONS
IONIZING RADIATIONS
ISOTOPES
LIGHT NUCLEI
MATRIX ELEMENTS
MEV RANGE
MEV RANGE 10-100
MULTIPOLE TRANSITIONS
NUCLEAR REACTIONS
NUCLEI
NUCLEON REACTIONS
ODD-EVEN NUCLEI
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
POLARIZED BEAMS
PROTON REACTIONS
QUADRUPOLE MOMENTS
RADIATIONS
RESONANCE
SILICON 30 TARGET
STABLE ISOTOPES
SUM RULES
TARGETS