Spin alignment and density matrix measurement in sup 28 Si+ sup 12 C orbiting reaction

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

DOI:https://doi.org/10.1103/PhysRevC.43.1789· OSTI ID:5547854

Ray, A ^[1]; Shapira, D; Halbert, M L; Gomez del Campo, J; Kim, H J ^[2]; Sullivan, J P ^[3]; Shivakumar, B; Mitchell, J ^[4]

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1. Joint Institute for Heavy Ion Research, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (US)
2. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (US)
3. Cyclotron Institute, Texas A M University, College Station, Texas 77843 (US)
4. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut 06511 (US)

Gamma-ray angular correlations have been measured for the damped reactions {sup 12}C({sup 28}Si,{sup 12}C){sup 28}Si between {theta}{sub c.m.}=120{degree} and 160{degree} for {ital E}{sub c.m.}=43.5 and 48 MeV. The spin alignments and density matrices have been deduced from the observed angular distribution of the gamma rays for {sup 28}Si states in {minus}10{lt}{ital Q}{lt}0 and {minus}16{lt}{ital Q}{lt}0 MeV for {ital E}{sub c.m.}=43.5 and 48 MeV, respectively, and for {sup 12}C(2{sub 1}{sup +}) state in strongly damped region {ital Q}{lt}{minus}10 MeV. We find that the spin angular momenta of the nuclei are poorly aligned with respect to the normal to the reaction plane and the density matrices for the {sup 12}C(2{sub 1}{sup +}) and {sup 28}Si states are almost diagonal with respect to the direction of motion of the outgoing particle. We also find qualitatively similar behavior of the spin alignments for {sup 28}Si states in strongly damped region. The measured density matrices and spin alignments are consistent with the picture of formation of a long-lived dinuclear complex undergoing orbiting, bending, and wriggling motions, but not with those obtained from statistical compound nucleus or sticking-model calculations.

• DOE Contract Number: FG05-87ER40361; AC05-84OR21400; AC02-76ER03074
• OSTI ID: 5547854
• Journal Information: Physical Review, C (Nuclear Physics); (USA), Journal Name: Physical Review, C (Nuclear Physics); (USA) Vol. 43:4; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ANGULAR CORRELATION
ANGULAR DISTRIBUTION
CARBON 12 TARGET
CHARGED-PARTICLE REACTIONS
COMPOUND-NUCLEUS REACTIONS
CORRELATIONS
DENSITY MATRIX
DISTRIBUTION
EVEN-EVEN NUCLEI
GAMMA SPECTRA
HEAVY ION REACTIONS
ISOTOPES
LIGHT NUCLEI
MATHEMATICAL MODELS
MATRICES
NUCLEAR REACTIONS
NUCLEI
ORIENTATION
SILICON 28
SILICON 28 REACTIONS
SILICON ISOTOPES
SPECTRA
SPIN ORIENTATION
STABLE ISOTOPES
STATISTICAL MODELS
TARGETS