Giant dipole resonances built on excited states in 90Zr through radiative proton capture

We have studied the ⁸⁹Y(p, γ_i)⁹⁰Zr reaction populating the states of ⁹⁰Zr at 0.0, 1.761, 2.186, 2.321 and 2.743 MeV. The 90° cross sections were measured from E_p = 3.7 to 11.5 MeV. The data were analysed by the statistical and direct-semidirect models. Spectroscopic factors of low-lying states in ⁹⁰Zr were determined.     

Purity of analog spin in isobaric analog resonances

It is shown that the position of the pole of the inverse averageS-matrix of an isolated isobaric analog resonance (IAR) is a very useful parameter, which allows one to distinguish between the weak and the strong coupling case of the finestructure distribution of the resonance. It gives also a direct measure of the purity of analog spin of the resonance. As an example the lowest IAR in²⁰⁸Bi is discussed.     

A dependence of inclusive pion double charge exchange

The A dependence of the forward cross section for inclusive pion double charge exchange on nine target nuclei from ⁶Li to ²⁰⁹Bi at T₀ = 0.59 GeV, as well as the cross section for ⁶Li, ⁷Li, and ¹²C nuclei at T₀ = 0.59, 0.75, and 1.1 GeV, was measured with the 3-m magnetic spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow). The resulting A dependence is well described within the model involving two sequential single charge exchanges and taking into account the renormalization of the amplitude for pion single charge exchange in a nucleus. A relatively weak energy dependence of the cross section for the ⁶Li, ⁷Li, and ¹²C nuclei agrees with the analogous dependence obtained previously for the ¹⁶O nucleus, but it contradicts the predicted sharp decrease in the cross section within the model involving two sequential single charge exchanges. This result provides an additional piece of evidence that the contribution from the mechanism of inelastic Glauber rescattering is significant at T₀ ? 0.6 GeV.     

Giant resonances on excited states

We derive modified RPA equations for small vibrations about excited states. The temperature dependence of collective excitations is examined. The formalism is applied to the ground state and the first excited state of ⁹⁰Zr in order to confirm a hypothesis which states that not only the ground state but every excited state of a nucleus has a giant resonance built upon it.     

Correlation effects in pion double charge exchange in the f72 shell

Analog and non-analog transitions have been measured in the reactions ⁴⁸Ca(π⁺, π⁻)⁴⁸Ti and ⁴⁸Ti(π⁺, π⁻)⁴⁸ Cr at pion energies of 130, 180, 235, and 292 MeV, and θ=5°. The ratios of cross sections for the different transitions are discussed in terms of different models of DCX which offer contrasting explanations.     

E1 radiation decay of isobaric analog resonances

Within the framework of the shell-optical model a quantitative interpretation for partial E1 radiation widths of isobaric analog resonances (IAR) has been proposed for near-magic nuclei over a wide atomic mass range. Spin-flip transitions as well as non-spin-flip ones are considered. A dependence of polarization effects on the spin-isospin part of the quasiparticle effective interaction is cleared up for transitions of different type. The results of calculations are compared with the experimental data.     

Giant dipole resonances of nonmagic nuclei

A method is described for calculating giant dipole resonances of nonmagic nuclei by constructing the nuclear wave functions on the basis of deformed one-particle orbitale. The residual-interaction potential, which is taken into account in the calculation of the dipole states, includes the dependence on the quantum numbers K, which are integrals of motion in this method. Oscillator strengths are calculated as functions of the energy of the giant resonance.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 1, pp. 7–13, January, 1970.