Partial width fluctuation method of determining nuclear level density

Comparison of giant dipole resonance decay in stiffMo92and softMoKicińska‐Habior1, Snover2, Behr3 et al. 1992Phys. Rev. C232130View full textAdd to dashboardCite

“…[18]. Level In the shape of the deduced photon absorption cross sections a broadening of the GDR in both szMo' and Mo' nuclei, as compared to the ground-state GDR, is clearly visible with increasing temperature and spin; however, the apparent deformation splitting is unresolved.…”

“…4 total level-density curves for some nuclei important in the decay of szMo' and iooMo' calculated in the Reisdorf parametrization with y 1=18. 5 MeV, ro -1.153 fm and odd-A reference (solid curves) as well as the Piihlhofer parametrization with a = A/8 MeV i (dot-dashed curves) and a = A/9 MeV i with the Wigner term included (dashed curves) are shown together with some experimental data (solid points) from counting levels and for Zr from the analysis of partial width fluctuations [18]. Since there is no experimental information about the level densities for nuclei of interest above E~12 MeV, we cannot favor any of these curves.…”

Radiative strength functions for dipole transitions in 90Zr

“…The heat of the (p, γ 0 ) reaction on the 89 Y nucleus is 8.3548 (16) MeV; therefore, the compound nucleus formed is excited to the energy of 12.5 MeV at incidentproton energies not exceeding the effective threshold for the opening of the competing neutron channel (through the reaction 89 Y(p, n 1 ) 89 Zr at E p = 4.24 MeV). At this excitation energy, the attained density of states even in this even-even spherical nucleus of 90 Zr, which is magic in the number of neutrons, N = 50, exceeds (see, for example, [20]) 10 4 MeV −1 , which must satisfy the requirements of applicability of a statistical description. On the basis of an analysis of investigations of the (p, n), (p, p), (p, p ′ ), and (p, γ) reactions on the 89 Y nucleus and on neighboring nuclei [11,12,[19][20][21][22][23][24], (γ, γ) and (γ, γ ′ )) reactions on the 90 Zr nucleus [2,25], as well as the (n, γ) reaction on the isotopes neighboring 90 Zr isotope [5,6], one can conclude that the distances between resonance levels having identical spins and parities in the product compound nucleus 90 Zr obey the Wigner distribution, while the protonic and radiative widths follow two independent Porter-Thomas distributions.…”

“…The closed triangles and open circles in Fig.1a represent the level densities obtained in [35] from the reactions 90 Zr(p, p ′ ) and 90 Zr(e, e ′ ) for the 2 + and 2 − states, respectively. The open triangles in Fig.1b correspond to the density of levels for the 1 − states that was obtained from a statistical analysis of partial width fluctuations manifesting themselves in the excitation function measured for the reaction 89 Y(p, γ 0 ) 90 Zr at incident-proton energies in the range of E p = 2.6 ÷ 3.3 MeV [20]. The open boxes stand for data on discrete levels of respective spin-parity.…”

“…The closed circles stand for the cross sections measured in [14] at an angle of 55 • for E p values in the range between 4.75 and 5.0 MeV with a step of 10 keV for a target of identical equivalent thickness. A strongly fluctuating curve represents the cross sections for the (p, γ 0 )-reaction that were determined after the respective normalization from the relative intensities measured in [20] under the aforementioned conditions for direct gamma-transitions populating the ground state of the 90 Zr nucleus. The dashed, dash-and-double-dot, and solid curves in Fig.4 represent the results obtained by calculating partial cross sections with the radiative strength functions obtained on the basis of, respectively, the SLO, KMF, and MLO2 models.…”