Giant resonances and bound collective states observed in the scattering of 92. 5-MeV electrons from the closed-neutron-shell nucleus /sup 89/Y between excitation energies from 2. 0 to 55 MeV

Journal Article · Thu Sep 01 04:00:00 EDT 1977 · Phys. Rev., C; (United States)

DOI:https://doi.org/10.1103/PhysRevC.16.970· OSTI ID:7082103

Pitthan, R; Buskirk, F R; Dally, E B; Shannon, J O; Smith, W H

92.5-MeV electrons were used to study in /sup 89/Y the excitation range between 2 and 55 MeV. Above neutron threshold, broad electric resonances have been seen at 14.0 (63A/sup -1/3/) MeV (E2, ..delta..T = 0) and 28 (125A/sup -1/3/) MeV (E2, ..delta..T = 1). The total width of the isoscalar E2 resonance is (4.5 +- 0.4) MeV and its strength (56 +- 6) % energy-weighted sum rule (E2, ..delta..T = 0). For the isovector E2 resonance only a minimal value of 7 MeV for the width can be given which is connected with (48 +- 5) % of the isovector sum rule. The strength of the E1 resonance (T/sub less-than/(104 +- 10) % of the Thomas-Reiche-Kuhn sum rule) agrees well with (..gamma..,n) measurements, thus giving a check for the accuracy of the evaluating methods employed. A structure around 19--20 MeV, believed to be the T/sub greater-than/part of the giant dipole resonance, carries (8 +- 3) % of the E1 sum rule. In addition to these generally well known states, clustering of E3 strength, (13 +- 2) % energy-weighted sum rule (E3, ..delta..T = 0), was found at 6.75 and 8.05 MeV; the enveloping line shape of these clusters was best described by a Breit-Wigner term. Other concentrations of strength include E3 at 2.6 MeV, (15 +- 3) % energy-weighted sum rule (E3, ..delta..T = 0), E2 at 4.0 MeV, (11 +- 3) % energy-weighted sum rule (E2, deltaT = 0), and E3 strength at 13.5 MeV. No resonance other than the E1 was found around 17 MeV, thus ruling out in /sup 89/Y the existence of a monopole state with 100% sum rule proposed for /sup 90/Zr from (..cap alpha..,..cap alpha..') and (e,e') measurements. In contrast to heavy nuclei, no resonant 3h..omega.. E3 strength could be located.

• Research Organization: Department of Physics and Chemistry, Naval Postgraduate School, Monterey, California 93940
• OSTI ID: 7082103
• Journal Information: Phys. Rev., C; (United States), Journal Name: Phys. Rev., C; (United States) Vol. 16:3; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BORN APPROXIMATION
BOUND STATE
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DWBA
ELECTRON REACTIONS
ENERGY RANGE
EQUATIONS
GIANT RESONANCE
INELASTIC SCATTERING
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
ISOVECTORS
LEPTON REACTIONS
MATHEMATICAL MODELS
MATRIX ELEMENTS
MEV RANGE
MEV RANGE 10-100
MULTIPOLARITY
NUCLEAR MODELS
NUCLEAR REACTIONS
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
RESONANCE
SCATTERING
SECONDS LIVING RADIOISOTOPES
SHELL MODELS
STABLE ISOTOPES
SUM RULES
TARGETS
TENSORS
VECTORS
YTTRIUM 89
YTTRIUM 89 TARGET
YTTRIUM ISOTOPES