出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The non-selective 31P(3He,t)31S reaction has been studied for the first time using 20- and 25-
MeV 3He beams from the tandem Van de Graaff accelerator at Yale University’s Wright Nuclear
Structure Laboratory. The Yale Engemagnetic spectrograph has been used to momentum-analyze
reaction products; a position-sensitive ionization drift chamber backed by a scintillator at the focal
plane has been used to identify tritons and measure the excitation energies of corresponding
states in 31S. Proton branching ratios and spins of 30P+p resonances have also been constrained
by measuring the angular correlations of decay protons in coincidence with the tritons using the
Yale Lamp Shade Array of silicon strip detectors. The 31S energy-level scheme has been considerably
extended and refined above the proton threshold of 6133 keV, and the new information
has been used to calculate the thermonuclear 30P(p,g )31S reaction rate up to T = 10 GK. Most
importantly, the existence of new resonances at Ec.m. = 194.0(25) and 266.4(27) keV has been
deduced which should have a significant impact on ONe nova nucleosynthesis and the classification
of presolar ONe nova grains. It is recommended that these resonances be targeted in future
direct measurements of the 30P(p,g )31S reaction using radioactive 30P ion beams.
