The (t, p) reaction with the even isotopes of Sm

Blocking of coupling to the 02 + excitation in 154Gd by the [505]11/2- neutron in 155Gd

“…However the |0 + 2 levels in N = 90 nuclei are very weakly populated in single-particle transfer [10][11][12][13] and electron scattering [14] experiments. They are also relatively weakly populated in (p,t) two-neutron pick-up reactions [15,16] but strongly in (t,p) two-neutron stripping reactions [17,18]. These latter data indicate that a considerable part of the |0 + 2 configuration consists of two quasi-neutrons in time-reversed orbits.…”

Congruent band structures in 154Gd : Configuration-dependent pairing, a double vacuum and lack of $ \beta$ -vibrations

“…If one assumes that the 0 + 2 levels correspond to collective β-vibrations it remains unclear why there would be a e-mail: jfss@tlabs.ac.za a substantial difference in the population patterns of these states. For nuclei with N ≥ 92 most of the two-neutron transfer strength is concentrated in the ground states [17][18][19][20][21][22]24], which is expected [25] for superfluid nuclei with a ground-state vacuum |0 + 1 well described by the BCS or Hartree-Fock-Bogolyubov theories [26].One should keep in mind that for the N = 88 and 90 nuclei even the most sophisticated models [2,4,27] fail to predict a β-vibration below about 1.5 MeV, adding further doubts about the interpretation of these states as β-vibrations. A totally different approach has been adopted by the Yale group [28] in which the 0 + 2 levels become s = 2 boson excitations [29][30][31] at a critical point X (5) symmetry.…”

“…It has usually been assumed that these 0 + 2 levels are collective β-vibrations based on the ground state |0 + 1 vacuum in spite of the observation that they are very weakly excited in inelastic electron scattering [15,16], which is unusual for states with a collective nature. The N = 88 0 + 2 levels are strongly populated in (p,t) two-neutron pickup reactions [17][18][19][20][21] but are weakly populated in (t,p) two-neutron stripping reactions [22,23]. In contrast the N = 90 0 + 2 levels are weakly populated in the (p,t) reactions and strongly populated in the (t,p) reactions.…”

“…If one assumes that the 0 + 2 levels correspond to collective β-vibrations it remains unclear why there would be a e-mail: jfss@tlabs.ac.za a substantial difference in the population patterns of these states. For nuclei with N ≥ 92 most of the two-neutron transfer strength is concentrated in the ground states [17][18][19][20][21][22]24], which is expected [25] for superfluid nuclei with a ground-state vacuum |0 + 1 well described by the BCS or Hartree-Fock-Bogolyubov theories [26].…”

Investigation of discrete states and quasidiscrete structures observed in Sm150 and Sm152 using the Humby1, Simón2, Beausang3 et al. 2016Phys. Rev. C6030View full textAdd to dashboardCite

“…This has led to this region of the nuclear chart being the focus of intense experimental and theoretical study, see for example references [1][2][3][4][5][6]. In the early two-neutron transfer experiments by Maxwell [7] and Bjerregaard [8] excited J π = 0 + states were observed to have large cross sections relative to the ground state in the 152 Sm(p,t) and 150 Sm(t,p) reactions. This was interpreted in terms of shape coexistence [7,8] and the rapid onset of deformation, inviting further interest in these nuclei.…”