Inelastic alpha scattering studies of the low-energy octupole resonance

Journal Article · Tue Aug 01 04:00:00 EDT 1978 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.18.741· OSTI ID:6669436

Moss, J M; Brown, D R; Youngblood, D H; Rozsa, C M; Bronson, J D

Beams of 96 and 115 MeV ..cap alpha.. particles have been used to study the distribution of isoscalar octupole strength in 18 nuclei from /sup 40/Ca to /sup 208/Pb. A prominent broad peak (GAMMA approx. 2.5 MeV) is observed at E/sub x/ approx. 30/A/sup 1/3/ MeV in nuclei from /sup 66/Zn to /sup 197/Au. No broad peak is observed in this excitation energy range in /sup 208/Pb or /sup 40/Ca and lighter nuclei. The oscillatory angular distributions of the (..cap alpha..,..cap alpha..') reaction exciting this peak are in excellent agreement with l = 3 distorted-wave Born approximation calculations. Studies of the angular range from sigma/sub lab/ = 3.5/sup 0/ to 6/sup 0/ in /sup 116/Sn indicate very little contribution from l = 1 strength. Energy- weighted sum rule fractions for this low-energy octupole resonance are generally in the range from 15% to 20%; this corresponds to 1/2 to 2/3 of the expected 1h..omega.. octupole strength. The overall distribution of octupole strength in spherical nuclei, including the absence of the low-energy octupole resonance in /sup 40/Ca and /sup 208/Pb, is in very good agreement with random-phase approximation calculations. The low-energy octupole resonance undergoes a pronounced change in structure in soft-vibrational and deformed nuclei. Theoretical calculations for the low-energy octupole resonance in /sup 154/Sm account qualitatively for the data.

• Research Organization: Cyclotron Institute and Physics Department, Texas A M University, College Station, Texas 77843
• OSTI ID: 6669436
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 18:2; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ALPHA REACTIONS
ANGULAR DISTRIBUTION
ARSENIC 75 TARGET
BORN APPROXIMATION
CALCIUM 40 TARGET
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DEFORMED NUCLEI
DISTRIBUTION
DWBA
ELEMENTS
ENERGY RANGE
EQUATIONS
GIANT RESONANCE
GOLD 197 TARGET
INELASTIC SCATTERING
LEAD 208 TARGET
METALS
MEV RANGE
MEV RANGE 10-100
MEV RANGE 100-1000
MOLYBDENUM 100 TARGET
MOLYBDENUM 92 TARGET
MOLYBDENUM 96 TARGET
NEODYMIUM 142 TARGET
NUCLEAR REACTIONS
NUCLEI
RESONANCE
SAMARIUM 144 TARGET
SAMARIUM 148 TARGET
SAMARIUM 154 TARGET
SCATTERING
SILVER
SUM RULES
TARGETS
TIN 116 TARGET
TIN 118 TARGET
TIN 124 TARGET
TRANSITION ELEMENTS
YTTRIUM 89 TARGET
ZINC 66 TARGET
ZIRCONIUM 90 TARGET