Yrast levels of 220Ra populated in the 208Pb(14C, 2n) reaction

Celler, Anna; Briançon, Ch.; Dionisio, J.S.; Lefèbvre, A.; Vieu, Ch.; Ż̷ylicz, J.; Kulessa, R.; Mittag, C.; Fernandez-Niello, J.; Lauterbach, C.; Puchta, H.; Riess, F.

doi:10.1016/0375-9474(85)90252-0

Cited by 42 publications

(13 citation statements)

References 23 publications

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“…A strong hindrance of dipole transitions in comparison to the 22~ [27] and 222Th [39] cases is found.…”

Section: Discussionmentioning

confidence: 84%

“…All the effects of such an alignment (see 1-24-26, 13]) are clearly seen in the experimental data on 23~ The K~= 0-band is compressed in respect to the ground-state band, so that these two bands tend to form an hybridized sequence (see Fig. 10), as it is found to occur at lower spins in the lighter actinides (see [27,28] and the references quoted therein).…”

Section: The Negative-paritymentioning

confidence: 80%

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Coulomb excitation of230Th with32S,84Kr and142Nd projectiles

Kulessa

Briançon

Lefèbvre

et al. 1989

Z. Physik A - Atomic Nuclei

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The Coulomb excitation measurements for the 23~ nucleus with 328, 84Kr and 142Nd projectiles are presented. The use of different projectiles allowed us to get information in the ground-state band and side bands. The energy spectrum of the ground-state band and of the lowest negative-parity band have been investigated up to the spin value I=24 + and I=19-(21), respectively. Five side bands (K~=0+,2+,2~, 1-,2-) were observed also. The branching ratios for a large number of transitions in the spin region I< 10 for ~= + l and 1<9 for re=-1 are analysed. The full set of experimental data contains information on the mixing of the adiabatic states and on the nuclear response to the electromagnetic field of ;:-radiation. It is shown that the experimental data may be explained taking into account the coupling of the ground-/3-and two 7-bands and also of the K~= 0-, 1-and 2-negative-parity bands. An enhancement of the transitions from the ~-to the/~-band in respect to the transitions from the 7 to the ground band and from the /~-to the ground band is reported. The mixing of the negative-parity bands is found to be typical for the alignment of the octupole-vibrational angular momentum. The strong spin dependence of the intrinsic matrix elements of the electric-dipole operator follows from the branching ratios of inter-and intra-band transitions from the K s=0 states.

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“…A strong hindrance of dipole transitions in comparison to the 22~ [27] and 222Th [39] cases is found.…”

Section: Discussionmentioning

confidence: 84%

Section: The Negative-paritymentioning

confidence: 80%

Coulomb excitation of230Th with32S,84Kr and142Nd projectiles

Kulessa

Briançon

Lefèbvre

et al. 1989

Z. Physik A - Atomic Nuclei

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“…Finally, the isomeric ratios for 196 Au and 198 Au produced via transfer processes displayed a different energy dependence and differ in absolute value: in the case of neutron removal from 197 Au, the isomeric ratios are higher than for the transfer of a neutron to 197 Au. Sub-barrier fusion of 6 He with 206 Pb was measured by Wolski et al [46] in the energy range from 14-28 MeV using a stacked-foil activation technique and radiochemical analysis via α-particle detection. The elastic scattering at 18 MeV was simultaneously measured during the beam exposure period in order to obtain an accurate value for 210 Po production in this reaction.…”

Section: Ormentioning

confidence: 99%

“…An explanation for this difference was given in terms of mixing of bound and unbound levels in 199 Au. Fusion of 8 He with 206 Pb was studied by Parkar et al [54] at energies near the Coulomb barrier, using a radiochemical technique with stacked targets of 206 Pb separated by mylar and Al spacers. The yield of the 210 Po evaporation residue (half-life of 138 days) was counted off-line after the Pb targets were dissolved and a 209 Po tracer was added.…”

Section: Fig 7 Excitation Functions Formentioning

confidence: 99%

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Elastic scattering, fusion, and breakup of light exotic nuclei

2016

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Abstract. The present status of fusion reactions involving light (A < 20) radioactive projectiles at energies around the Coulomb barrier (E < 10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron-and proton-rich systems. Possible physical explanations for the observed differences are also reviewed.

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Spectroscopy of221Th

et al. 1985

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A positive and a negative parity band in 221Zffl have been investigated via the 2~ 3n) ~ 2 ~Th reaction. Strong El transitions con~ete with stretched E2 transitions deexciting levels of alternating parity. The measured averaged =2.6 9 10 -6 fm -2 is similar to that observed in neighbouring nuclei. The level scheme 1~y be interpreted assuming an octupole defo~ned core.The light nuclei in the Pa-Th region around A-222 have been the subject of recent examinations from an experimental as well as theoretical .point of view. The most striking features are low-lying negative parity states and strong El transitions connecting states of alternating parity. Experimentally, high-spin states were measured mainly for the even-even nuclei 22~[1,2,3,4], z• [5,6] and for the odd nuclei Zl~Ra [7] and 219Ac [8]. The observed level schemes have been discussed in the framework of IBA-calculations [9] , a molecular cluster model [10] or static octupele deformations [I I, 12,13] .In this note we report on the measurements of high-spin states in 22 ~Th and compare the data with calculations allowing for octupole deformed shapes. No excited levels of 22 iTh have been known until now.In order to produce 22 iTh ' the reaction 20 spb ( ~O, 3n) 221That bombarding energies of 84.5, 86 and 87 MeV was used. The 400 nA pulsed beaJn of tile FAn-tandem accelerator at the MPI f~r Kern_Dhysik in Heidelberg has been employed. The target consisted of an enriched 130 bg/cm 2 2~ sandwiched between carbon foils of "30 bg/cm 2. The produced evaporation residues were deflected in an electrostatic separator [ 14 ] and detected in a 2000 mm 2 Si-surface barrier detector. Without this additional coincidence signal y-spectroscopy would be very dJ ffJcult due to large y-background from fission and other reaction channels, y-rayswere measured with 7 Ge (i) -detectors under 90 ~ and 145 ~ with respect to the beam axis, 5 of them were shielded with NaI-or BGO-anticompton crystals, y-recoil and y-y-recoil coincidences were recorded during a beam time of 57 h beam on the target. Fig. Ib shows a typical y-recoil spectrum, figs. Ic-lf projections out of the y-y-recoil matrix, gated on a specific transition. Fig. la shows the intensity ratios under 145 ~ and 90 ~ wit/l respect to the beam axis together with the expected angular distributions for stretched dipole and quadrupole transitions. From this figure the multipolarity of the radJation was determined. The prominent transitions could be assigned to 22 iTh from excitation functions and the observed G-decay chain in the recoil detector. For the 250.9 keV transition the E2 character was determined from a previous conversion e]ectron m~asur~m~nt [I]. This transition is in cascade with all others and is assigned as the transition to the band hoad. The absence of the dipole transitions in the conversion electron spectrum is a strong indication for the El character of these transitions. For every dipole transition two quadrupole transitions are missing in the coincidence spectra and vice-versa. The decay sc...

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Yrast levels of 220Ra populated in the 208Pb(14C, 2n) reaction

Cited by 42 publications

References 23 publications

Coulomb excitation of230Th with32S,84Kr and142Nd projectiles

Coulomb excitation of230Th with32S,84Kr and142Nd projectiles

Elastic scattering, fusion, and breakup of light exotic nuclei

Spectroscopy of221Th

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