The STAR CollaborationNuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons -composed of an antiproton, antineutron, and antilambda hyperon -produced by colliding gold nuclei at high energy. Our analysis yields 70 ± 17 antihypertritons ( Nuclei are abundant in the universe, but antinuclei that are heavier than the antiproton have been observed only as products of interactions at particle accelerators (1, 2). Collisions of heavy nuclei at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) briefly produce hot and dense matter that has been interpreted as a quark gluon plasma (QGP) (3, 4) with an energy density similar to that of the universe a few microseconds after the Big Bang. This plasma contains roughly equal numbers of quarks and antiquarks. As a result of the high energy density of the QGP phase, many strange-antistrange (ss) quark pairs 1 are liberated from the quantum vacuum. The plasma cools and transitions into a hadron gas, producing nucleons, hyperons, mesons, and their antiparticles.Nucleons (protons and neutrons) contain only up and down valence quarks, while hyperons (Λ, Σ, Ξ, Ω) contain at least one strange quark in its 3-quark valence set. A hypernucleus is a nucleus that contains at least one hyperon in addition to nucleons. All hyperons are unstable, even when bound in nuclei. The lightest bound hypernucleus is the hypertriton ( 3 Λ H), which consists of a Λ hyperon, a proton, and a neutron. The first observation of any hypernucleus was made in 1952 using a nuclear emulsion cosmic ray detector (5). Here, we present the observation of an antimatter hypernucleus. Production of antinuclei:Models of heavy-ion collisions have had good success in explaining the production of nuclei by assuming that a statistical coalescence mechanism is in effect during the late stage of the collision evolution (4, 6). Antinuclei can be produced through the same coalescence mechanism, and are predicted to be present in cosmic rays. An observed high yield could be interpreted as an indirect signature of new physics, such as Dark Matter (7, 8). Heavy-ion collisions at RHIC provide an opportunity for the discovery and study of many antinuclei and antihypernuclei.The ability to produce antihypernuclei allows the study of all populated regions in the 3-dimensional chart of the nuclides. The conventional 2-dimensional chart of the nuclides organizes nuclear isotopes in the (N, Z) plane, where N is the number of neutrons and the Z is the number of protons in the nucleus. This chart can be extended to the negative sector in the (N, Z) plane by including antimatter nuclei. Hypernuclei bring a third dimension into play, based on the strangeness quantum number of the nucleus. The present study probes the territory of antinuclei with non-zero strangeness ( Fig. 1), where proposed ideas (9-12) related to t...

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Titanate nanotubes and nanoribbons have been synthesized hydrothermally using commercial anatase nanopowder (particle size ≈50−400 nm) and NaOH. The samples were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (TEM−SAED), and X-ray diffraction (XRD). It has been found that the hydrothermal temperature and the treatment duration have a strong effect on the morphology control of the resulting products. At a fixed temperature of 180 °C, the morphology of the products changes with the hydrothermal duration (5−72 h). Hollow nanotubes with an outer diameter of about 10 nm were formed at treatment durations between 5 and 20 h. Bundles of nanoribbons with widths ranging from 50 to 500 nm and lengths up to several tens of micrometers were produced at a treatment duration of 72 h. Experimental results on samples treated at different temperatures (135−195 °C) for different durations revealed the transformation of the nanotubes into nanoribbons after specific treatment duration at any selected temperature, so we predict that optimizing the hydrothermal temperature and treatment duration may lead to a better control of the product morphology.

A novel route was proposed to completely coat aluminum borate nanowires by in situ providing the precursor for BN coating. Uniformly BN-coated Al18B4O33 nanowires could be obtained by the reaction of Al4B2O9 nanowires with ammonia at high temperature. The high-temperature unstable Al4B2O9 nanowires were converted into Al18B4O33 nanowires, simultaneously evaporated boron oxide. The reaction between the in situ generated vapors and ammonia ensures that the BN layers are attached tightly on the surface of the as-formed Al18B4O33 nanowires.

Aluminum borate (Al18B4O33) nanorods doped with Eu3+ and Eu2+ were synthesized via a simple calcination method. Both nanorods are of straight morphology and smooth surface, with the average diameter of ∼80nm. The structural and compositional characteristics have been investigated by x-ray diffraction, infrared spectra, and various microscopy techniques. A possible growth mechanism was proposed for the synthesis of the doped Al18B4O33 nanorods. Photoluminescence measurements indicate that Al18B4O33:Eu3+ nanorods exhibit emission peaks at 590, 595, 612, and 617nm, and Al18B4O33:Eu2+ nanorods display a broad green emission band centered at ∼540nm.