Search for highly excited states in light nuclei with three-body reactions

Various three-body break-up reactions resulting from the bombardment of ⁷Li with 120 MeV ³He have been measured simultaneously in a kinematically complete experiment. Missing-mass spectra have been deduced for ⁴H, ⁴He, ⁴Li, ⁵He, ⁵Li, ⁶He, ⁶Li and ⁷Li. The ground states of ⁴H and ⁵He are well described as n-t and n-α P-wave final-state interactions, respectively. Evidence is found for relatively narrow states at very high excitation energies in several nuclei. The results are compared with those of other authors and with various theoretical predictions.     

Many-particle excited states in nuclei

Energies, quadrupole moments and shapes of many-particle excited states in ¹²C and ¹⁶O are calculated. The connection of the obtained results with the cluster model is discussed.     

Halo or skin in the excited states of some light mirror nuclei

The properties of three pairs of mirror nuclei ¹³N- ¹³C, ¹⁵N- ¹⁵O and ²¹Na- ²¹Ne (these mirror nuclei are all made of a good inert core plus an unpaired valence nucleon) are investigated by using the nonlinear relativistic mean-field (RMF) theory. It is found that the calculated binding energies with two different parameter sets are very close to the experimental ones for both the ground states and the excited states except for the large deformed nuclei. The calculations show that the 2s_1/2 excited states of ¹⁵N and of ²¹Na are both weakly bound with a proton halo and a proton skin (or a pigmy proton skin), respectively. In addition, the 1d_5/2 excited state of ¹³C and the 2s_1/2 excited state of ¹⁵O are also weakly bound with a neutron skin, respectively. The ratio of the valence nucleon radius to matter radius is deduced and it can be regarded as an additional criterion for the existence of exotic structure. The unbound 2s_1/2 and 1d_5/2 excited states of ¹³N are also discussed.     

The deformation of the ground and excited states in the Ag and Sn nuclei

The microscopic calculation of the potential energies in the ground and excited states of Ag and Sn nuclei has been performed. The single particle Nilsson potential and the shell correction Strutinski method have been used. The weak sensitivness to nonaxial deformation has been found for even neighbours of these nuclei. The small tendency towards prolate deformation of the ground and excited one-quasiparticle states originating from theg _9/2 proton subshell in^101–105Ag odd isotopes has been noticed. The behaviour with quadrupole e and hexadecapole ε₄ deformation of the ground and two-quasiparticle excited 0⁺ states originating from thed _5/2,g _9/2 andg _7/2 proton subshells andh _11/2 neutron subshell in^112–118Sn has been investigated. The small quadrupole deformation of the excited 0⁺ states has been found what is in agreement with the experimental data concerning the rotational bands build on the first excited 0⁺ states in Sn isotopes.     

First observation of excited states in 197At: the onset of deformation in neutron-deficient astatine nuclei

Excited states in the Z= 85 nucleus ¹⁹⁷At have been identified for the first time using the recoil-decay-tagging (RDT) technique. The excitation energy of these states is found to be consistent with the systematics of neutron-deficient astatine nuclei and with theoretical calculations indicating that the nucleus may be deformed in its ground state. Received: 8 January 1999     

Continuum effects in excited states of light hypernuclei

The spectra of the hypernuclei ⁶_ΛLi, ⁷_ΛLi and ⁹_ΛBe are calculated in the lambda particle - neutron hole basis using the Green's function method. The model includes the effects of the Λ continuum. As a result the Λ escape widths are calculated. for the various hypernuclear states. A comparison with the recently measured strangeness exchange (K⁻, π⁻) reaction results is made.     

Scattering of light exotic atoms in excited states

The differential and total cross-sections for the scattering of muonic, pionic, kaonic and antiprotonic hydrogen in excited states from atomic hydrogen have been calculated for the purpose of atomic cascade calculations. The scattering problem is treated in a fully quantum mechanical framework which takes the energy shifts and, in the case of the hadronic atoms, the widths of the ns states into account. The validity of semiclassical approximations is critically examined. Received 4 December 2001 and Received in final form 4 February 2002     

On the rotational states in light nuclei

Some properties of the projected Hartree-Fock functions which describe the ground state bands in ⁸Be, ¹²C and ²⁰Ne, and the excited 8p-8h band in ¹⁶O are studied in order to answer the question whether these states correspond to real rotational motion in these light nuclei.     

Theory of the excited states of deformable even-even nuclei

The excited states of nonspherical even-even nuclei are discussed taking the change in nuclear shape during excitation into account.     

Dynamic hyperpolarizabilities of excited states of hydrogen

On the basis of the generalized Sturm expansion of the radial part of the Coulomb Green function, a computational method is proposed and numerical results are presented for the dynamic hyperpolarizability γ and the corrections E ⁽⁴⁾ (quadratic in the light intensity) to the quasi-energy of the ground and excited states of hydrogen with principal quantum numbers n≤5 in a monochromatic light field. In this approach, the problem is reduced to the summation of well-convergent double series of the hypergeometric kind, which ensures reliable numerical results both for states with a large n, and in a wide range of field frequencies ω, including the above-threshold frequency range of ?ω?|E _n | (|E _n | is the ionization potential of the state |nlm〉 under investigation). We consider the frequency dependence of γ and E ⁽⁴⁾, their differences for the cases of linear and circular polarizations of the field, and the relation between their real and imaginary parts, which determine the laser field-induced corrections to the position and width of energy levels. For n=5, the significant role of mixing the |nlm〉 states with different values of l by a laser field in the region of resonances on intermediate bound states is demonstrated. The linear (in intensity) corrections to the photoionization cross section for excited states are analyzed and the threshold intensity corresponding to the onset of atomic level stabilization is estimated for a number of states with n=3 and n=5.

     

Transition probabilities and static moments of excited states in even-even nuclei

A new approach is made to calculate the generalized single-particle density matrixp ^μv in even-even nuclei. It is shown that this quantity is included in the three particle response function, for which we derived a renormalized equation. Taking into account in a consequent way the effective particle-hole interaction we received a formula for the static moment of excited states and the transition probability between such states which is essentially different from the usual RPA theory.     

A method for the direct measurement of excited nuclei deformation

In this work, the energy shift of X-ray photons at two-photon transition, depending on conversion (either at transition between the second and first excited states or at transition from the first to the ground level), is studied. It is possible to very precisely determine the energy shift of an X-ray photon (on the order of 1 eV) by registering the X-ray photon in coincidence with an X-ray photon of another transition with high resolution detectors; this allows one to determine the change of the mean square radius of the nucleus in the excited state.     

A method of angular momentum projection for excited states in even-even nuclei

A method of angular momentum projection for the excited states in even-even nuclei is formulated within the framework of the Hartree-Bogoliubov theory. A preliminary application of this method is performed for the K=0^? band in ¹⁶²Er.     

Low lying 8 and 12 hole states in light nuclei

The positions of 4, 8 and 12 hole states in alpha particle nuclei from ²²⁰Ne to ⁵²Fe are calculated using a j dependent monopole-monopole interaction with an A⁻¹ dependence. The 12 hole states in ⁴⁰Ca and ⁴⁴Ti are lower than the 8 hole states and are calculated to be at 5 and 3 MeV respectively. B(E2)'s are calculated for ⁴⁰Ca and the nature of the 5.21 MeV state is discussed.     

Quenched magnetic transitions from high spin states in light nuclei

Recent investigations of stretchedM 6 transitions in thes-d shell have uncovered the unexpected systematic trend that isoscalarM 6 transitions are two to three times more retarded than the isovector ones. We present the result of a microscopic calculation analyzing the different mechanisms usually invoked in the formation of the quenching and suggest that an additional argument based on the difference in structure between isoscalar and isovector transition densities may be playing a predominant role in explaining the data.     

Life-time of the excited states of the Ru99 and Ru101 nuclei

Using a fast-slow coincidence apparatus, the life-times of the 89, 442, 617 and 897 keV excited states of Ru⁹⁹ and the 127, 307, 311, and 545 keV excited states of Ru¹⁰¹ were measured, these levels being excited by the decay of the nuclei Rh⁹⁹, Rh¹⁰¹, and Tc¹⁰¹. The experimental values of the probabilities of certain-transitions were calculated from the results.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, Vol. 16, No. 9, pp. 82–85, September, 1973.