Prospect for a 60 GHz multicharged ECR ion source.

The conceptual design of a fourth generation hybrid electron cyclotron resonance (ECR) ion source operated at 60 GHz is proposed. The axial magnetic mirror is generated with a set of three Nb3Sn coils, while the hexapole is made with room temperature (RT) copper coils. The motivations for such a hybrid development are to study further the ECR plasma physics and the intense multicharged ion beams' production and transport at a time when a superconducting (SC) hexapole appears unrealistic at 60 GHz. The RT hexapole coil designed is an evolution of the polyhelix technology developed at the French High Magnetic Field Facility. The axial magnetic field is generated by means of 3 Nb3Sn SC coils operated with a maximum current density of 350 A/mm2 and a maximum coil load line factor of 81%. The ECR plasma chamber resulting from the design features an inner radius of 94 mm and a length of 500 mm. The radial magnetic intensity is 4.1 T at the wall. Characteristic axial mirror peaks are 8 and 4.5 T, with 1.45 T minimum in between.

How to Reach a Thousand-Second in-Plane Polarization Lifetime with 0.97-GeV/c Deuterons in a Storage Ring.

We observe a deuteron beam polarization lifetime near 1000 s in the horizontal plane of a magnetic storage ring (COSY). This long spin coherence time is maintained through a combination of beam bunching, electron cooling, sextupole field corrections, and the suppression of collective effects through beam current limits. This record lifetime is required for a storage ring search for an intrinsic electric dipole moment on the deuteron at a statistical sensitivity level approaching 10^{-29} e cm.

Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies.

The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19 MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

Evolution of wing shape in hornets: why is the wing venation efficient for species identification?

Wing venation has long been used for insect identification. Lately, the characterization of venation shape using geometric morphometrics has further improved the potential of using the wing for insect identification. However, external factors inducing variation in wing shape could obscure specific differences, preventing accurate discrimination of species in heterogeneous samples. Here, we show that interspecific difference is the main source of wing shape variation within social wasps. We found that a naive clustering of wing shape data from taxonomically and geographically heterogeneous samples of workers returned groups congruent with species. We also confirmed that individuals can be reliably attributed to their genus, species and populations on the basis of their wing shape. Our results suggested that the shape variation reflects the evolutionary history with a potential influence of other factors such as body shape, climate and mimicry selective pressures. However, the high dimensionality of wing shape variation may have prevented absolute convergences between the different species. Wing venation shape is thus a taxonomically relevant marker combining the accuracy of quantitative characters with the specificity required for identification criteria. This marker may also highlight adaptive processes that could help understand the wing's influence on insect flight.

Differences in caste dimorphism among three hornet species (Hymenoptera: Vespidae): forewing size, shape and allometry.

Caste shape dimorphism (CShD) has previously been studied in wasps through comparison of different body parts, originating from different imaginal discs. Using geometric morphometrics with a new protocol for measuring wings of pinned specimens from natural history collections, we tested CShD of three hornet species in an organ developed from a single imaginal disc: the forewing. Gaussian mixture models retrieved most castes and species levels, confirming that caste is an important component of wing variations in females of these hornets. Size and allometry - the influence of size on shape - contribution to wing dimorphism between castes was major, but failed to explain the entire shape dimorphism. This deviation from simple allometric scaling was not similar in the three species: in Vespa tropica, allometric directions in the shape space differed between castes, whereas in V. crabro and V. velutina, they were similar but a significant part of CShD resulted from lateral transpositions. These results clearly indicate that queens are not just enlarged workers. They also support that the different patterns of CShD may result from different developmental mechanisms. Finally, they highlight that even in a highly social group like hornets, there is still variation in caste dimorphism among species.

Measurement of the generalized polarizabilities of the proton in virtual Compton scattering at Q2=0.92 and 1.76 GeV2.

We report a virtual Compton scattering study of the proton at low c.m. energies. We have determined the structure functions P(LL)-P(TT)/epsilon and P(LT), and the electric and magnetic generalized polarizabilities (GPs) alpha(E)(Q2) and beta(M)(Q2) at momentum transfer Q(2)=0.92 and 1.76 GeV2. The electric GP shows a strong falloff with Q2, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a falloff; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q2, compensated at higher Q2 by a paramagnetic contribution from piN intermediate states.