Active-Sterile Neutrino Transformation and r-Process Nucleosynthesis

The type II supernova is considered as a candidate site for the production of heavy elements. Since the supernova produces an intense neutrino flux, neutrino scattering processes will impact element formation. We examine active-sterile neutrino conversion in this environment and find that it may help to produce the requisite neutron-to-seed ratio for synthesis of the r-process elements.Comment: 5 pages including 2 figures, to appear in the Proceedings of the Conference on the Intersections of Nuclear and Particle Physics 200

Nucleosynthesis in the Outflow from Gamma Ray Burst Accretion Disks

We examine the nucleosynthesis products that are produced in the outflow from rapidly accreting disks. We find that the type of element synthesis varies dramatically with the degree of neutrino trapping in the disk and therefore the accretion rate of the disk. Disks with relatively high accretion rates such as 10 M_solar/s can produce very neutron rich nuclei that are found in the r process. Disks with more moderate accretion rates can produce copious amounts of Nickel as well as the light elements such as Lithium and Boron. Disks with lower accretion rates such as 0.1 M_solar/s produce large amounts of Nickel as well as some unusual nuclei such as Ti-49, Sc-45, Zn-64, and Mo-92. This wide array of potential nucleosynthesis products is due to the varying influence of electron neutrinos and antineutrinos emitted from the disk on the neutron-to-proton ratio in the outflow. We use a parameterization for the outflow and discuss our results in terms of entropy and outflow acceleration.Comment: 12 pages, 12 figures; submitted to Ap

Neutrino Interactions in the Outflow from Gamma-Ray Burst Accretion Disks

We examine the composition of matter as it flows away from gamma ray burst accretion disks, in order to determine what sort of nucleosynthesis may occur. Since there is a large flux of neutrinos leaving the surface of the disk, the electron fraction of the outflowing material will change due to charged current neutrino interactions. We calculate the electron fraction in the wind using detailed neutrino fluxes from every point on the disk and study a range of trajectories and outflow conditions for several different accretion disk models. We find that low electron fractions, conducive to making r-process elements, only appear in outflows from disks with high accretion rates that have a significant region both of trapped neutrinos and antineutrinos. Disks with lower accretion rates that have only a significant region of trapped neutrinos can have outflows with very high electron fractions, whereas the lowest accretion rate disks with little trapping have outflow electrons fractions of closer to one half.Comment: 11 pages, 10 figure

Understanding Supernova Neutrino Physics using Low-Energy Beta-Beams

We show that fitting linear combinations of low-energy beta-beam spectra to supernova-neutrino energy-distributions reconstructs the response of a nuclear target to a supernova flux in a very accurate way. This allows one to make direct predictions about the supernova-neutrino signal in a terrestrial neutrino detector.Comment: To appear in the proceedings of International School of Nuclear Physics: 27th Course: "Neutrinos in Cosmology, in Astro, Particle and Nuclear Physics". Erice, Sicily, Italy, 16-2

Untangling supernova-neutrino oscillations with beta-beam data

Recently, we suggested that low-energy beta-beam neutrinos can be very useful for the study of supernova neutrino interactions. In this paper, we examine the use of a such experiment for the analysis of a supernova neutrino signal. Since supernova neutrinos are oscillating, it is very likely that the terrestrial spectrum of supernova neutrinos of a given flavor will not be the same as the energy distribution with which these neutrinos were first emitted. We demonstrate the efficacy of the proposed method for untangling multiple neutrino spectra. This is an essential feature of any model aiming at gaining information about the supernova mechanism, probing proto-neutron star physics, and understanding supernova nucleosynthesis, such as the neutrino process and the r-process. We also consider the efficacy of different experimental approaches including measurements at multiple beam energies and detector configurations.Comment: 13 pages, 11 figures, accepted for publication in Phys. Rev.