Splitting of the Giant Resonance for Deformed Nuclei

Abstract

Photoneutron yield measurements have been made for terbium, tantalum, and gold with good energy resolution from threshold up to 25 Mev. Neutron-production cross sections were obtained directly from the experimental points without smoothing the raw data. Corrections were made for the multiple production of neutrons above the (y,2n) thresholds. The giant resonances for terbium and tantalum were found to be split into two resonances as predicted by Okamoto and Danos. The giant resonances for all three nuclei were fitted by the superposition of two Lorentz shape resonance lines. The intrinsic quadrupole moments determined from these fits to the experimental data were: terbium, -f5.6±0.6 barns; tantalum, -f5.7±0.3 barns; and gold, +1.6=1=0.6 barns.

Photodisintegration of tantalum

“…(iii) The cross sections σ(γ, sn) obtained in beams of bremsstrahlung photons were presented in [14][15][16][17][18].…”

“…The cross sections calculated for reactions involving [11], (open circles) [12], (open squares) [13], and (closed circles) [19]. [14], (open triangles) [15], (open boxes) [16], (closed circles) [17], and (open circ) [18].…”

Photodisintegration ofU235

“…6 According to Danos 7 and Okamoto, 8 a splitting is to be expected in the giant-dipole resonance of the compound-nucleus-formation cross section. Although such a splitting has been observed in the rare-earth nuclei by several investigators, 9,10 it has not been detected in the fissionable elements.…”

“…The multiplicity can be expressed in terms of a quantity JU defined as the average number of neutrons emitted per formation of the compound nucleus. If the formation cross section <r(7,total) is defined as o-fototal) = <r(y,n)+<r(y,2n)-\ h<K%/) +*(y,»f)+<r(y,2nf)+--- 9 (3) then 11 is given as M=<r(7,iV)/^(7,total).…”

Nuclear Photodisintegration

“…It is clear that in strongly deformed nuclei the simple calculations so far described do not apply. The individual j's are no longer good quantum numbers but are replaced by the n's, the projection (62,63) giant resonance widths r (exp. ) and splittings !…”