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The 19F(p, αγ)16O reaction is of crucial importance for Galactic 19F abundances and CNO cycle loss in first generation Population III stars. Due to its extremely small cross sections, the 19F(p, αγ)16O reaction has not been measured in the low energy part of the Gamow window(70-200 keV). As a day-one campaign, the experiment was performed under the extremely low cosmicray-induced background environment of the China JinPing Underground Laboratory(CJPL), one of the deepest underground laboratories in the world. The γ-ray yields were measured over Ec.m. =72.4–344 keV, covering the full Gamow window for the first time. The direct experimental data will help people to expound the fluorine over-abundances, energy generation, as well as heavy-element nuclosynthesis scenario in asymptotic giant branch (AGB) stars, with the astrophysical model on the firm ground. [ABSTRACT FROM AUTHOR]

Type I X-ray bursts (XRBs) are the most frequently observed thermonuclear explosions in nature. The 22Mg(α,p)25Al reaction plays a critical role in XRB models. However, experimental information is insufficient to deduce a precise 22Mg(α,p)25Al reaction rate for the respective XRB temperature range. A new measurement of 25Al+p resonant scattring was performed up to the astrophysically interested energy region of 22Mg(α,p)25Al. Several resonances were observed in the excitation functions, and their level properties have been determined based on an R-matrix analysis. In particular, proton widths and spin-parities of four natural-parity resonances above the α threshold of 26Si, which can contribute the reaction rate of 22Mg(α,p)25Al, were first experimentally determined. [ABSTRACT FROM AUTHOR]

Experimental studies on astrophysical reactions involving radioactive isotopes (RI) often accompany technical challenges. Studies on such nuclear reactions have been conducted at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study, the University of Tokyo. We discuss two cases of astrophysical reaction studies at CRIB; one is for the 7Be+n reactions which may affect the primordial 7Li abundance in the Big-Bang nucleosynthesis, and the other is for the 22Mg(α, p) reaction relevantin X-raybursts. [ABSTRACT FROM AUTHOR]

Studies on nuclear astrophysics, nuclear structure, and other interests have been performed using the radioactive-isotope (RI) beams at the low-energy RI beam separator CRIB, operated by Center for Nuclear Study (CNS), the University of Tokyo. A typical measurement performed at CRIB is the elastic resonant scattering with the inverse kinematics. One recent experiment was on the a resonant scattering with 7Li and 7Be beams. This study is related to the astrophysical 7Li/7Be(α,γ) reactions, important at hot p-p chain and vp-process in supernovae. There have also been measurements based on other experimental methods. The first THM measurement using an RI beam has been performed at CRIB, to study the 18F(p, α)15O reaction at astrophysical energies via the three body reaction ²H(18F, α15O)n. The 18F(p, α)15O reaction rate is crucial to understand the 511-keV γ-ray production in nova explosion phenomena, and we successfully evaluated the reaction cross section at novae temperature and below experimentally for the first time. [ABSTRACT FROM AUTHOR]

CRIB (CNS Radioactive Ion Beam separator) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Studies on proton and alpha resonance scatterings, (α, p) reactions, and other types of measurements (β-decay lifetimes etc.) have been performed using RI beams at CRIB, motivated by interests on astrophysical reactions and exotic nuclear structure. Among the studies at CRIB, the measurement of 7Li+α/7Be+α resonant scatterings are presented. [ABSTRACT FROM AUTHOR]

Several reactions have been experimentally studied, including the 12N(d,n)13O and the ones induced by the 3He+12C entrance channel. The former was carried out at the CRIB facility of University of Tokyo, aiming to indirectly determine the astrophysical reaction rates of the 12N(p,γ)13O reaction. For the 3He+12C entrance channel, many excited states of several nuclei are populated and the angular distribution of each state is being analyzed. [ABSTRACT FROM AUTHOR]

Astrophysical 18Ne(α,p)21Na reaction is one of the most probable breakout routes, which lead to the rp-process from the hot-CNO cycle, converting the initial CNO elements into heavier elements in Type I x-ray bursters. Presently, there is no much experimental cross-section data reported at the energy of astrophysical interest, and resonant spectroscopic information in compound 22Mg is scarce as well. The experiment has been carried out by using the CNS radioactive ion beam separator (CRIB). Resonant properties in 22Mg have been studied via the resonant elastic scattering of 21Na+p, and cross section of the time-reversal reaction of 21Na(p,α)18Ne been measured simultaneously. A wide excitation energy region up to Ex ∼ 9.5 MeV in 22Mg has been scanned with a thick-target method. Some preliminary results will be reported. [ABSTRACT FROM AUTHOR]

Astrophysical stellar reactions at extremely high temperatures involve a variety of problems both in nuclear reactions and nuclear structures. Specifically, the problems in the νpprocess were discussed in this talk based on our recent experimental results with low-energy RI beams and a simulation study. The νp-process is one of the key processes for investigating the mechanism of type II supernovae, and the process could be possibly responsible for "the excess production" of p-nuclei around mass 90-100. Alpha cluster resonances have been discovered experimentally to play a crucial role for the stellar (α, p) reactions just above the alpha threshold. Neutron induced reactions in the proton-rich nuclear regions in the νp-process are also suggested to play an important role, which involve nuclear structures of high level density at high excitation energies, probably giant resonances. The discussion also covered the p-nuclei production through the νp-process at around mass 100. [ABSTRACT FROM AUTHOR]

The first direct measurement of the 11C(α, p)14N reaction cross section of astrophysical interest has been performed for the center-of-mass energies from 1 to 4.5 MeV with the CRIB (Center for Nuclear Study Radioactive Ion Beam separator). We successfully distinguished the transition to the ground state of 14N and that to the second excited state with a comparable yield. The resonant shapes in the preliminary excitation function for the ground state transition have been confirmed to be consistent with the ones from the time-reversal reaction data of previous experiments. [ABSTRACT FROM AUTHOR]

CRIB (CNS Radioactive Ion Beam separator ) is a low-energy RI beam separator at the Center for Nuclear Study (CNS) of the University of Tokyo. Using the RI beams at CRIB, many measurements on proton alpha resonance scatterings, (α,p) reactions, and others were performed in recent years mainly for studying astrophysical reactions and exotic nuclear structure. Among them, the results on the 7Li+α resonance scatterings are presented. [ABSTRACT FROM AUTHOR]

Nuclear astrophysics activities with CNS RI beam separator (CRIB) are reported together with the present status of the CRIB facility which is supported by the AVF upgrade project for the total development of the low-energy RIB facility. The activities include direct and indirect measurements of stellar reactions especially relevant to explosive burning processes such as nova and supernovae. Some recent results are discussed together with a scope of the facility. [ABSTRACT FROM AUTHOR]

The measurement of the resonant alpha scattering and the 21Na(α, p) reaction were performed for the first time in inverse kinematics with the thick target method using a 21Na radioisotope (RI) beam. This paper reports the current result of alpha scattering measurement and its astrophysics implication. [ABSTRACT FROM AUTHOR]