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ONe novae thermonuclear simulations still show uncertainties in the abundance of the final elements. This comes from the uncertainties that are present in some reaction rates that are considered to be important. One of this is the resonant proton capture on 30P. For decades various experiments tried to restrain the large variations in the reaction rates and many improvements have been made, but the results are still inconclusive. Decay spectroscopy This proceeding paper aims to make a comparison between two indirect methods that can be used to reach the reaction rate of the above-mentioned reaction, by briefly describing the procedure and detection methods used. [ABSTRACT FROM AUTHOR]

The 9C breakup reaction was investigated in order to obtain information about the inverse reaction: 8B(p,γ)9C at astro-physical energies within the NP1412SAMURAI29R1 experiment. The 8B(p,γ)9C reaction gives a possible path to the hot pp chain pp-IV at high temperatures and away from it toward a rapid alpha-process rap-I at high temperatures and densities and therefore is important in understanding nucleosynthesis in super-massive hot stars in the early universe, including possible bypass of the 3α-process. For this experiment it was proposed to use a combination of nuclear and Coulomb dissociation measurements (on a light target Be or C and on a heavy target Pb, respectively) at energy of 160 A MeV to extract structure information, which will allow to evaluate the radiative proton capture cross section at low energies and from there the reaction rate. The current work is focused on the development of Monte Carlo simulations for Coulomb breakup mechanism of 9C as well as on the Geant4 simulations of the resulting particle trajectories through the experimental setup, including passage of the particles through the magnetic field of the SAMURAI spectrometer. [ABSTRACT FROM AUTHOR]

We have recently developed a gas based detection system called AstroBox, motivated by nuclear astrophysics studies. The goal was to detect very low-energy protons from β-delayed p-decay with reduced beta background and improved energy resolution. The detector was tested using the β-delayed proton-emitter 23Al previously studied with a set-up based on thin double-sided Si strip detectors. The proton spectrum obtained with AstroBox showed no beta background down to ∼80 keV. The low energy (206 keV, 267 keV) proton peaks were positively identified, well separated, and the resolution was improved. [ABSTRACT FROM AUTHOR]

Decay spectroscopy is one of the oldest indirect methods in nuclear astrophysics. We have developed at TAMU techniques to measure beta- and beta-delayed proton decay of sd-shell, proton-rich nuclei. The short-lived radioactive species are produced in-flight, separated, then slowed down (from about 40 MeV/u) and implanted in the middle of very thin Si detectors. These allowed us to measure protons with energies as low as 200 keV from nuclei with lifetimes of 100 ms or less. At the same time we measure gamma-rays up to 8 MeV with high resolution HPGe detectors. We have studied the decay of 23Al, 27P, 31Cl, all important for understanding explosive H-burning in novae. The technique has shown a remarkable selectivity to beta-delayed charged-particle emission and works even at radioactive beam rates of a few pps. The states populated are resonances for the radiative proton capture reactions 22Na(p,γ)23Mg (crucial for the depletion of 22Na in novae), 26mAl(p,γ)27Si and 30P(p,γ)31S (bottleneck in novae and XRB burning), respectively. More recently we have radically improved the technique using a gas based detector we call AstroBox. [ABSTRACT FROM AUTHOR]

The 18O(p,α)15N reaction is of great importance in several astrophysical scenarios, as it influences the production of key isotopes such as 19F, 18O and 15N. In this work, a high accuracy 18O(p,α)15N reaction rate is proposed, based on the simultaneous fit of direct measurements and of the results of a new Trojan Horse experiment. In particular, we have focused on the study of the broad 660 keV 1/2+ resonance. Since Γ∼100-300 keV, it strongly influences the nearly-zero-energy region of the cross section by means of the low-energy tail of the resonant contribution and dominates the cross section at higher energies. Here we provide a factor of 2 larger reaction rate above T∼0.5 109 K based over our new improved determination of its resonance parameters. [ABSTRACT FROM AUTHOR]

We discuss the use of one-nucleon removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. The breakup reactions are proved to be good spectroscopic tools and can be used to study a large number of loosely bound proton- or neutron-rich nuclei over a wide range of beam energies. As peripheral processes, they can be used to extract asymptotic normalization coefficients (ANCs) from which non-resonant capture reaction rates of astrophysical interest can be calculated parameter free. In this talk, we present results of a proton-breakup experiment carried out at GANIL (France) with a cocktail beam centered around 23Al at 50 MeV/nucleon. Momentum distributions of the breakup fragments, inclusive and in coincidence with gamma rays detected by EXOGAM Germanium clover array, were measured in the focal plan of SPEG energy-loss spectrometer. We present in particular the investigations of reaction rates for 22Mg(p,γ)23Al and 23Al(p,γ)24Si important for novae and X-ray bursts, respectively. [ABSTRACT FROM AUTHOR]

The MARS group at TAMU has developed a new experimental technique to measure very low energy protons from β-delayed proton-decay of proton-rich nuclei produced and separated with the MARS recoil spectrometer at TAMU. Recently we have investigated the β-delayed p-decays of 23Al [1], and 31Cl [2], and obtained information on the resonances in the 22Na(p,γ)23Mg and 30P(p,γ)31S reactions, respectively. These reactions are important in explosive H-burning in Novae [3]. Recently an experiment looking at the β-delayed p-decay of 20Mg was also done in order to obtain information on resonances in the 19Ne(p,γ)20Na reaction. A simple setup consisting of a telescope made of a thin double sided Si strip detector (p-detector) backed or sandwiched between two thick Si detectors (β-detectors) was designed. We studied different W1 and BB2 p-detectors made by MSL, and found that the thinner detectors with a small cell size are best to measure proton energies as low as 2-300 keV. [ABSTRACT FROM AUTHOR]

In order to understand primordial and stellar nucleosynthesis, we have studied 2H(d,p)3H reaction at 0, 4 MeV down to astrophysical energies. Knowledge of this S-factor is interesting also to plan reactions for fusion reactors to produce energy. 2H(d,p)3H has been studied through the Trojan Horse Method applied to the three-body reaction 2H(3He,pt)H, at a beam energy of 17 MeV. Once protons and tritons are detected in coincidence and the quasi-free events are selected, the obtained S-factor has been compared with direct reactions results. Such data are in agreement with the direct ones, and a pole invariance test has been obtained comparing the present result with another 2H(d,p)3H THM one, performed with a different spectator particle (see fig. 1). [ABSTRACT FROM AUTHOR]

We discuss the use of one-nucleon removal reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. These breakup reactions are good spectroscopic tools and can be used to study a large number of loosely bound proton- or neutron-rich nuclei over a wide range of beam energies. They are peripheral processes that can be used to extract asymptotic normalization coefficients (ANC) from which direct capture proton reaction rates of astrophysical interest can be calculated parameter free. We emphasize the importance of reaction model calculations and of exclusive measurements to check them. We review several cases: the breakup of 8B, 9C, 15C and 23Al. Firrst we review how we have used the data for the breakup of 8B at energies from 30 to 1000 MeV/nucleon on light and heavy targets to extract the astrophysical factor S17(0) = 18.7±1.9 eV·b for the key reaction for solar neutrino production. Glauber model calculations in the eikonal approximation and in the optical limit using different effective NN interactions were found to give consistent, though slightly different results, for both 8B and 9C cases, enabling also us to evaluate the precision of the method. The third case is that of a neutron-rich nucleus and the ANC alone does not lead to unambiguous estimates of the associated (n,γ) capture reaction. The 23Al case is that of an sd-shell nucleus, suspected of halo properties, for which our recent GANIL experiment revealed a complex configuration mixing in its ground state. The method outlined here has the big advantage that it can be used for beams of low quality, such as cocktail beams, and intensities as low as a few pps. As such it is very appropriate for the existing and future radioactive beam facilities. The breakup reactions are therefore complementary or a very good alternative to the use of proton and neutron transfer reactions (the ANC method) which require radioactive nuclear beams of much better purity and intensity. [ABSTRACT FROM AUTHOR]

The Trojan Horse Method (THM) is an unique indirect technique allowing to measure astrophysical rearrangement reactions down to astrophysical relevant energies. The basic principle and a review of the recent applications of the Trojan Horse Method are presented. The applications aiming to the extraction of the bare astrophysical Sb(E) for some two-body processes are discussed. [ABSTRACT FROM AUTHOR]

Survey of the most important results of astrophysical research on the 3He cyclotron beam in NPI Rˇezˇ is presented. ANCs for some proton capture reactions of the CNO stellar cycle are discussed. Results of the last experiments on the isotopic gas target of 15N are also mentioned. [ABSTRACT FROM AUTHOR]

It was expected that γ rays from 18F and 22Na would be observed in massive One novae, but neither has been to date. The 17F(p,γ)18Ne and 22Mg(p,γ)23Al reactions may play important roles in the production and destruction of 18F and 22Na. We have determined the asymptotic normalization coefficients for 18Ne and 23Al through measurements of peripheral neutron transfer reactions in the mirror nuclear systems. We use the ANCs to calculate the astrophysical S-factors and reaction rates for these two reactions. [ABSTRACT FROM AUTHOR]

The reaction cross section of the radiative proton capture on the drip line nucleus 12N was studied at the Cyclotron Institute at Texas A&M University. We have employed the indirect Asymptotic Normalization Coefficient method to determine the direct radiative component of the astrophysical S-factor of the 12N(p,γ)13O reaction. A value of 0.31(5) keV·b was found at zero energy. Interference between direct and resonant captures leads to a further enhancement of a factor of two. The reaction was investigated in relation to the evolution of hydrogen-rich massive objects, Population III stars, because of the role that it may play in the hot pp chain nuclear burning processes occurring in such stars. [ABSTRACT FROM AUTHOR]

The Trojan Horse Method allows for the measurements of cross sections in nuclear reactions between charged particles at astrophysical energies. The basic features of the method are discussed and recent applications are presented. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]