Nuclear States with Abnormal Radii

The radius of a nuclear state is one of the most important its characteristics. Presently there were developed some methods exploiting special features of the nuclear reactions leading to short – lived excited states and allowing determination of their radii. Evidence of existing nuclear excited states with enhanced radii (size isomers) was obtained

Possible Existence of Neutron-Proton Halo in 6Li

One of the most recent results was the determination of the proton halo in the first excited state of the 13N nucleus using of an analog of the MDM method for the charge exchange reactions (3He, t). It turned out that this state has the same radius as the mirror state 1/2+, 3.09 MeV in 13C.This observation allows us to take the next step and try to apply this approach to measure the radii of states. The increased radii in the isobar - analogue states of the 6He-6Li-6Be triplet, which may also have a halo structure, are not excluded. As a first step, we analyzed the published differential cross sections for inelastic scattering of 3He + 6Li with the excitation of the 2.19 MeV, 3+ state at energies 34 and 72 MeV and 3.56 MeV, 0+ state at energies 24.6 and 27 MeV. Probably the state 0+, 3.56 MeV has the same radius as its ”Borromian” isobar analogue 6He and is neutron-proton halo. The predicted enlarged radius because of the more extended wave function p - n, apparently, does not take place. We recall that the spatial structure of the 6He nucleus was predicted to be quite complex, in which correlations of two types appeared: ”cigar” and ”dineutron”. The question arises: does the structure of the state change so much when passing from 6He to the isobar-analoguein6Li,whichrequirestheintroductionofaspecialkindof“tango-halo”

Analytical approximation for the sphere-sphere Coulomb potential

A simple analytical expression, which closely approximates the Coulomb potential between two uniformly charged spheres, is presented. This expression can be used in the optical potential semiclassical analyses which require that the interaction be analytic on and near the real r-axis.Comment: 4 pages including 3 figures and 1 tabl

Diversity and Abundance of Hymenopterous Parasitoids Associated with Anastrepha fraterculus (Diptera: Tephritidae) in Native and Exotic Host Plants in Misiones, Northeastern Argentina

Some Major host species used by the tephritid fruit flies Anastrepha fraterculus (Wiede-mann) and Ceratitis capitata (Wiedemann), including Acca sellowiana (O. Berg) Burret, Campomanesia xanthocarpa O. Berg, Psidium guajava L., Prunus persica (L.) Batsch, Eriobotrya japonica (Thunb.) Lindl., Citrus reticulata Blanco var. Murcott, C. aurantium L., C. paradisi Macfadyen var. Dalan Dan, and C. paradisi var. Sudashi, were sampled for fruit fly larvae between Feb and Dec 2000 in the northernmost section of the Paranaense forest, in the Province of Misiones, NE Argentina. Both A. fraterculus and C. capitata were obtained from these host plant species, with A. fraterculus accounting for 93% of all tephritid puparia identified. Ten species of larval-pupal parasitoids were recovered from A. fraterculus; Doryctobracon areolatus (Szépligeti), D. brasiliensis (Szépligeti), Utetes anastrephae (Viereck), Opius bellus (Gahan), Diachasmimorpha longicaudata (Ashmead) (Opiinae, raconidae), Odontosema anastrephae Borgmeier, Lopheucoila anastrephae (Rohwer), Aganaspis pelleranoi (Brèthes) (Eucoilinae, Figitidae), Asobara anastrephae (Muessebeck) (Alyssinae, Braconidae), and Aceratoneuromyia indica (Silvestri) (Tetrastichinae, Eulophidae). All these parasitoids, with the exception of D. longicaudata and A. indica, are native to the Neotropical region. No parasitoids were recovered from C. capitata puparia. Asobara anastrephae and O. anastrephae are newly recorded in Argentina, whereas D. brasiliensis, U. anastrephae, and L. anastrephae are newly reported in Misiones. The eucoiline A. pelleranoi wasthe most abundant parasitoid species. Acca sellowiana and P. guajava harbored the highest parasitoid abundance and diversity.Fil: Schliserman, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Catamarca. Universidad Nacional de Catamarca. Centro de Investigaciones y Transferencia de Catamarca; ArgentinaFil: Ovruski Alderete, Sergio Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Decoll, Olga. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Misiones; ArgentinaFil: Wharton, Robert. Texas A&M University; Estados Unido

Open Problems in α\alpha Particle Condensation

$\alpha$ particle condensation is a novel state in nuclear systems. We briefly review the present status on the study of $\alpha$ particle condensation and address the open problems in this research field: $\alpha$ particle condensation in heavier systems other than the Hoyle state, linear chain and $\alpha$ particle rings, Hoyle-analogue states with extra neutrons, $\alpha$ particle condensation related to astrophysics, etc.Comment: 12 pages. To be published in J. of Phys. G special issue on Open Problems in Nuclear Structure (OPeNST

Search for states with enlarged radii in excited states of 12B

An experiment was done to search for states with a neutron halo in 12B. The measurements were carried out at the cyclotron of the University of Jyvaskyla (Finland) using Large Scattering Chamber (LSC). The idea of the work was to search for two states with the expected neutron halo, 1 ̄ and 2 ̄. Differential cross sections with excitation of 12B states, including abovementioned states, were observed. The preliminary calculations on halo radii by the method of asymptotic normalization coefficients for the 2 ̄ and 1 ̄ states which are in a discrete spectrum gave following values: 5.6 fm and 7.4 fm, which is much larger than the radius of the valence neutron in the ground state. But strictly the presence of a neutron halo can be confirmed only for 1 ̄ state. The 2 ̄ state can be considered only as candidate for halo. An unexpected result was obtained for the 3 ̄, 3.39 MeV state, which is in continuum 19 keV above the decay threshold 12B → 11B + n, preliminary estimation for its halo radius is ∼ 6.5 fm. This indicates that the halo can be present in this state as well. But strict conditions for neutron halo are not fulfilled in the same way as for 2 ̄ state. Until now, the neutron halo in unbound states has been observed only for the members of the rotational bands