Nuclear structure of 30S and its implications for nucleosynthesis in classical novae

The uncertainty in the 29P(p,gamma)30S reaction rate over the temperature range of 0.1 - 1.3 GK was previously determined to span ~4 orders of magnitude due to the uncertain location of two previously unobserved 3+ and 2+ resonances in the 4.7 - 4.8 MeV excitation region in 30S. Therefore, the abundances of silicon isotopes synthesized in novae, which are relevant for the identification of presolar grains of putative nova origin, were uncertain by a factor of 3. To investigate the level structure of 30S above the proton threshold (4394.9(7) keV), a charged-particle spectroscopy and an in-beam gamma-ray spectroscopy experiments were performed. Differential cross sections of the 32S(p,t)30S reaction were measured at 34.5 MeV. Distorted wave Born approximation calculations were performed to constrain the spin-parity assignments of the observed levels. An energy level scheme was deduced from gamma-gamma coincidence measurements using the 28Si(3He,n-gamma)30S reaction. Spin-parity assignments based on measurements of gamma-ray angular distributions and gamma-gamma directional correlation from oriented nuclei were made for most of the observed levels of 30S. As a result, the resonance energies corresponding to the excited states in 4.5 MeV - 6 MeV region, including the two astrophysically important states predicted previously, are measured with significantly better precision than before. The uncertainty in the rate of the 29P(p,gamma)30S reaction is substantially reduced over the temperature range of interest. Finally, the influence of this rate on the abundance ratios of silicon isotopes synthesized in novae are obtained via 1D hydrodynamic nova simulations.Comment: 22 pages, 12 figure

Production of Medical 99mTc Isotope Via Photonuclear Reaction

99mTc with a 6 hour half-life is one of the most important medical isotopes used for the Single-Photon Emission Computed Tomography (SPECT) inspection in hospitals of US, Canada, Europe and Japan.99mTc isotopes are extracted by the milking method from parent 99Mo isotopes with a 66 hour half-life. The supply of 99Mo isotopes now encounters a serious crisis. Hospitals may not suitably receive 99Mo medical isotopesin near future, due to difficulties in production by research nuclear reactors. Many countries are now looking for alternative ways to generate 99Mo isotopes other than those with research reactors. We discuss a sustained availability of 99mTc isotopes via the Mo(γ, n) photonuclear reaction, and discuss to solve technical problems for extracting pure 99mTc isotopes from other output materials of photonuclear reactions

Microdosimetric study for 400 MeV/A clinical carbon-beam.

13th SYmposium on Microdosimetr

New method to measure M1 strength using photonucelar reactions with linear polarized gamma-ray beam

The M1 strength from the ground state (or level density of 1+ states) is of importance for estimation of the interaction strength between a neutrino and a nucleus for the study of supernovae. To explore a new method to measure M1 strengths, we have measured neutron angular distributions with (gamma, n) reactions on Au, I, and natCu using linear polarized laser Compton scattering (LCS) gamma-ray beam at NewSUBARU. We also have measured neutron yields from (polarized gamma, n) reactions on a natFe target at 0, 10, 25, 45, 60, 70, and 90 degrees at NewSUBARU.14th International Symposium on Nuclei in the Cosmos XI

M1 Strength in Photonuclear Reactions with Linearly Polarized γ-ray Beam

The neutrino-nucleus interactions are important for understanding nucleosyntheses by neutrino-induced reactions as well as supernova explosion mechanisms. The M1 strength in atomic nuclei is important for estimation of neutrino-nucleus interactions. We have proposed a method using (γ, n) reactions with linear polarized laser Compton scattering (LCS) γ-rays to measure the M1 strength and verified a theoretical prediction

Characterisation of an ultra-miniature counter for Microdosimetric measurements in a therapeutic 400 MeV/A Carbon beam.

Single event spectra of a clinical carbon beam have been measured by an ultra-miniature tissure-equivalent proportional counter (UMC). In order to cover the energy range of the Bragg peak, the incident energy of the carbon beam was degraded by aluminium plates. Single event spectra for carbon-events incident to the UMC were analysed and selected at several carbon energies using thin scintillation counters. It was found that the dose weighted lineal energy distributions have a doublet peak structure due to incident carbon beam and fragment contributions