Results of the measurements of the excitation function in the deuteron-induced reaction 45 Sc(d,p) 46 Schavebeenobtainedattheenergyofincidentdeuteronsup to11.7MeV.Inaddition, dataforthe 45 Sc(d,t) 44 Screactionwereobtained. The experimentswereperformedusingthevariableenergycyclotronU-120M(NPI, ˇ Reand the Electrostatic Generator EG-5 (FLNP, JINR). The cross sections of the induced activities were measured using the stacked-foil technique. The measured excitation functions were similar to those observed for the 45 Sc( 6 He, 5 He ∗ ) 46 Sc reaction, studied at the accelerator complex for radioactive beams DRIBs (FLNR, JINR). The maximum probability of producing 46 Sc was also found close to the Coulomb barriers of these reactions. The compilation of available experimental data, obtained at deuteron and 6 He-energies near the Coulomb barrier, showed that the values of the cross sections at the maxima of the excitation functions obtained in (d, p) reactions and the reactions for one-neutron pickup from the 6 He projectiles have a different Z-dependence.

New results from a series of experiments dedicated to the study of the C-12 exotic state (the so-called Hoyle state) are presented. In spite of the many investigations that have been carried out, the structure of this state (which lies above the threshold for breaking up into three alpha particles) is still unknown. The different models assume that the nucleus has an abnormally large size in this excited state. However, until recently, methods for measuring the radii of unbound states have not been suggested. The best way to solve this problem seems to be by measuring the angular distributions of elastic and inelastic scattering of C-12 on different target nuclei, and the determination of the radii is based on the fact that, at small scattering angles, the cross sections for direct reactions at high enough energies behave like Frauenhofer diffraction on a black ball. Accordingly, an experiment was performed aimed at measuring the elastic and inelastic angular distributions of C-12 with an energy of (121.5 +/- 0.5) MeV on a C-12 target. The elastic scattering was measured in the angular range from 18 degrees to 50 degrees in the c.m. system with uncertainty in the angle of measurement equal to Delta theta = +/- 0.6 degrees. The inelastic cross section was measured for the C-12 excited state 2(+) (4.44 MeV) and 0(+) (7.65 MeV). Estimates were made for the diffraction radii for the ground and excited states. An increase was observed in the radius of the state at 7.65 MeV compared to those of the ground and first excited states.

New results from a series of experiments dedicated to the study of the 12 C exotic state (the so-called Hoyle state) are presented. In spite of the many investigations that have been carried out, the structure of this state (which lies above the threshold for breaking up into three alpha particles) is still unknown. The different models assume that the nucleus has an abnormally large size in this excited state. However, until recently, methods for measuring the radii of unbound states have not been suggested. The best way to solve this problem seems to be by measuring the angular distributions of elastic and inelastic scattering of 12 C on different target nuclei, and the determination of the radii is based on the fact that, at small scattering angles, the cross sections for direct reactions at high enough energies behave like Frauenhofer diffraction on a black ball. Accordingly, an experiment was performed aimed at measuring the elastic and inelastic angular distributions of 12 C with an energy of (121.5 ± 0.5) MeV on a 12 C target. The elastic scattering was measured in the angular range from 18° to 50° in the c.m. system with uncertainty in the angle of measurement equal to Δθ = ± 0.6°. The inelastic cross section was measured for the 12 C excited state 2 + (4.44 MeV) and 0 + (7.65 MeV). Estimates were made for the diffraction radii for the ground and excited states. An increase was observed in the radius of the state at 7.65 MeV compared to those of the ground and first excited states.

Experimental excitation functions are presented for 45Sc(d, p)46Sc, 45Sc(d, t)44Sc, 45Sc(6He, 5He*)46Sc and 45Sc(6He, α)47Sc reactions at projectile energies near the Coulomb barrier. The obtained excitation functions for reactions 45Sc(d, p)46Sc and 45Sc(6He, 5He*)46Sc have similar behavior and have a maxima near the Coulomb barriers of these reactions. The compilation of the available experimental data, obtained at deuteron- and 6He-energies near the Coulomb barrier, showed that the values of the cross sections at the maxima of the excitation functions obtained in (d, p) reactions and the reactions for one-neutron pickup from the 6He projectiles have a different Z-dependence.

Experimental results from measuring the energy dependences of cross sections of fusion and transfer reactions for 6Li beams and Pt targets are presented. The experiments were performed using the MSP-144 magnetic analyzer; stacks of platinum foils were installed at the focal plane of this analyzer. In the energy range 22.5–42.5 MeV, the energy resolution of the beam hitting the target stack was not worse than 0.25 MeV and that of the transmitted beam was not worse than 0.40 MeV. The yields of products of neutron and deuteron transfer reaction on target nuclei were measured using the γ activity induced in the platinum targets. Thus, excitation functions for transfer reactions were obtained in a wide energy range, including near the Coulomb barrier. It was shown that the basic reaction channel is the deuteron capture from 6Li. In this case, the maximum of the excitation function for 6Li breakup and subsequent deuteron capture lies near the Coulomb barrier of the reaction.

Excitation functions of the reaction products were measured for the reactions induced by He-4,He-6 projectiles on Pb-206,Pb-208 targets, leading to the same compound nucleus. This was accomplished by using the stacked-foil-activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive alp ha decays. The excitation functions for the 2n evaporation channels were obtained at energies below the sub-Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound He-6 projectile.

Excitation functions of the reaction products were measured for the reactions induced by 4,6He projectiles on 206,208Pb targets, leading to the same compound nucleus. This was accomplished by using the stacked‐foil‐activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive alp ha decays. The excitation functions for the 2n evaporation channels were obtained at energies below the sub‐Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6He projectile.

Experimental excitation functions are presented for fusion-evaporation and transfer reactions in the interaction of Li-6 with Bi and Pt targets. The data on the cross sections obtained for the produced evaporation residues are in agreement with calculations within the framework of the statistical model using the ALICE-MP code. Enhancement of the cross section for deuteron transfer reactions is observed at energies below the Coulomb barrier. The results are discussed from the point of view of how the nuclear cluster structure influences the probability of interaction at near-barrier energies.

Various excited states in 14C, above the α-decay threshold, are believed to possess a geometric arrangement of three α-particles covalently bound by the two delocalised valence neutrons. The 12C(16O, 14O)14C* reaction was studied at a beam energy of 234 MeV, at the ISL facility at the Hahn-Meitner-Institut (HMI), Berlin. The 14O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited 14C recoil break-up fragments were measured in coincidence using a double sided silicon strip detector array comprised of four detectors at backwards angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the 14C* → 10Be + α and 14C* → 13C + n decay channels and the branching ratios of these decays were calculated. Neutron emission was found to be favoured for the 12.96, 14.87, 16.72 and 18.6 MeV states. Evidence for α-decay was found for the 14.87, 18.6 and 21.4 MeV states; which are candidates for the three bodied molecular cluster structure of 14C.

Physics of Unstable Nuclei, pp. 221-229 (2008) No AccessCORE ⊗ (sd)3 STRUCTURES IN 17C, 16C AND 15C UP TO HIGH EXCITATION ENERGIESH. G. BOHLEN, W. VON OERTZEN, CH. SCHULZ, TZ. KOKALOVA, C. WHELDON, R. KALPAKCHIEVA, T. N. MASSEY, and M. MILINH. G. BOHLENhttp://www.hmi.de Hahn-Meitner-Institut Berlin, Glienocker Str. 100, 14109 Berlin, Germany, W. VON OERTZENhttp://www.hmi.de Hahn-Meitner-Institut Berlin, Glienocker Str. 100, 14109 Berlin, Germany, CH. SCHULZhttp://www.hmi.de Hahn-Meitner-Institut Berlin, Glienocker Str. 100, 14109 Berlin, Germany, TZ. KOKALOVAhttp://www.hmi.de Hahn-Meitner-Institut Berlin, Glienocker Str. 100, 14109 Berlin, Germany, C. WHELDONhttp://www.hmi.de Hahn-Meitner-Institut Berlin, Glienocker Str. 100, 14109 Berlin, Germany, R. KALPAKCHIEVAFlerov Laboratory for Nuclear Reactions, JINR, RU-141980 Dubna, RussiaInstitute for Nuclear Research and Nuclear Energy, BAS, Blvd. Tsarigradsko Shosse 72, BG-1784 Sofia, Bulgaria, T. N. MASSEYDepartment of Physics and Astronomy, Ohio University, Athens, Ohio 45701-2979, USA, and M. MILINRuđer Bošković Institute, Bijenicka 54, HR-10002 Zagreb, Croatiahttps://doi.org/10.1142/9789812776150_0034Cited by:0 (Source: Crossref) PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: Structures of 17C of the type 14C⊗ν(sd)3 have been studied up to high excitation energies using the (12C,9C) three-neutron transfer reaction on 14C at 231 MeV incident energy. In this reaction (3p2h)-configurations are directly populated selectively. The large negative Q-value (Q0 = -46.93 MeV) supports this selectivity for three-neutron configurations and high-spin states by dynamical matching conditions in the reaction mechanism, and higher-order transitions are suppressed. Tentative assignments could be made in this way. The experimental results are compared to shell-model calculations. The same structures have been also populated in 16C and 15C using the (12C, 9C) reaction on 12C and 13C targets. Nine states in the three carbon isotopes 17C, 16C and 15C show strong similarities in their properties. This concerns the excitation energies, which agree within ±0.23 MeV except for a constant shift of excitation energies in 16C by 5.82 MeV and in 15C by 6.65 MeV with respect to 17C, and these states have also similar widths and cross-section ratios. Therefore tentative assignments are discussed in the same way for 16C and 15C. Furthermore, the levels of the three isotopes have been investigated for band structures using the tentative assignments and shell-model calculations. Two bands could be identified in each isotope. Keywords: Transfer reactions A = 15, 16, 17Three-neutron configurationsShell-model calculationsTentative assignments FiguresReferencesRelatedDetails Recommended Physics of Unstable NucleiMetrics History KeywordsTransfer reactions A = 15, 16, 17Three-neutron configurationsShell-model calculationsTentative assignmentsPDF download

Excitation functions of the reaction products were measured for the reactions induced by 4,6He projectiles on 208,206Pb targets, leading to the same compound nucleus. This was accomplished by using the stacked-foil activation technique. The identification of the reaction products (accumulated in the Pb targets) was done by their radioactive α-decays. The excitation functions for the various products were obtained at energies including the sub-Coulomb barrier region. A large value of the fusion cross section was observed in the case of the reaction induced by the weakly bound 6He projectile.

The C-12(O-16,O-14)C-14 reaction was studied at a beam energy of 234 MeV. The O-14 ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited C-14 recoil break-up fragments were measured in coincidence with the O-14 ejectile using a double sided silicon strip detector array at backward angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the C-14(*)-> Be-10+alpha and C-14(*)-> C-13+n decay channels and the branching ratios and widths of these decays were calculated. Theoretical decay branches were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the spins, parities, and configurations of the states. Neutron emission was found to be favored for the 11.73, 12.96, 14.87, 16.72, and 18.6 MeV states. The 14.87, 18.6, and 21.4 MeV states were found to have a considerable width for alpha-decay and are candidates for the three bodied molecular cluster structure of C-14.

Excitation functions for evaporation residues in the reactions 206,208 Pb (6,4 He,2n 210 Po , as well as for the transfer reactions in the interaction of 6 He and 6 Li projectiles with Au and Pt were measured at the energies near the Coulomb barrier. Studied reactions were characterized by an increase in the cross-section compared to statistical model calculations.