Preface: Eighth European Summer School on Experimental Nuclear Astrophysics

We discuss the use of one-nucleon breakup reactions of loosely bound nuclei at intermediate energies as an indirect method in nuclear astrophysics. These are peripheral processes, therefore we can extract asymptotic normalization coefficients (ANC) from which reaction rates of astrophysical interest can be inferred. To show the usefulness of the method, three different cases are discussed. In the first, existing experimental data for the breakup of 8B at energies from 30 to 1000 MeV/u and of 9C at 285 MeV/u on light through heavy targets are analyzed. Glauber model calculations in the eikonal approximation and in the optical limit using different effective interactions give consistent, though slightly different results, showing the limits of the precision of the method. The results lead to the astrophysical factor S_17(0)=18.7+/-1.9 eVb for the key reaction for solar neutrino production 7Be(p,\gamma)8B. It is consistent with the values from other indirect methods and most direct measurements, but one. Breakup reactions can be measured with radioactive beams as weak as a few particles per second, and therefore can be used for cases where no direct measurements or other indirect methods for nuclear astrophysics can be applied. We discuss a proposed use of the breakup of the proton drip line nucleus 23Al to obtain spectroscopic information and the stellar reaction rate for 22Mg(p,\gamma)23Al.

Indirect methods in nuclear astrophysics with relativistic radioactive beams

Our understanding of stellar evolution depends on knowing beta-decay rates and reaction cross sections for a wide range of nuclear capture reactions. Direct laboratory measurements of important stellar reaction rates are hindered by low cross sections and, in some cases, the need for radioactive targets. Indirect techniques have been developed to determine reaction rates for systems that are particularly difficult to measure in a direct experiment. One of the indirect techniques involves measurements of Asymptotic Normalization Coefficients (ANCs) which determine the direct-capture contribution to a capture reaction. Also ANCs can be used to understand the role of subthreshold states in stellar capture. This essay gives an introduction to ANCs and describes how they are used in nuclear astrophysics. Examples are given of measurements which have been carried out with both stable and radioactive beams.

Breakup of loosely bound nuclei at intermediate energies as indirect method in nuclear astrophysics: 8B, 9C and the S17, S18 astrophysical factors

We discuss indirect methods that make use of transfer reactions to determine cross sections of reactions in stellar burning processes. We focus on two of them that have been extensively used in the past decades: the asymptotic normalization coefficients method and the Trojan horse method. We provide a comprehensive description of their theoretical as well as basic experimental features.

We discuss recent developments in indirect methods used in nuclear astrophysics to determine the capture cross sections and subsequent rates of various stellar burning processes, when it is difficult to perform the corresponding direct measurements. We discuss in brief, the basic concepts of Asymptotic Normalization Coefficients, the Trojan Horse Method, the Coulomb Dissociation Method, (d,p), and charge-exchange reactions.

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 l...

It is well known that measuring cross-sections of thermonuclear reactions at the low energies typical of astrophysical sites is very difficult. This is due to the presence of the Coulomb barrier between the interacting nuclei. For non-explosive scenarios at astrophysical sites, the relevant energies typically span from few tens to few hundreds of keV while the Coulomb barrier is in the order of MeV. The fusion processes then proceed via tunnel effect and their cross-sections are strongly depending on the probability of penetration through the barrier. In a first approximation, this probability is given by the Gamow factor. Owing to the exponential decrease in this factor with energy, the cross-section values of thermonuclear fusion processes in stellar systems often reach values as small as micro- and nanobarn and even lower ones. Neutron-induced reactions, in spite of the absence of Coulomb barrier, are also difficult to measure. Indeed, it is the possible presence of a centrifugal barrier that can hinder the measurement of the values of the cross-sections of these processes. In either cases the cross-sections of astrophysical nuclear processes result in experimental difficulties, due to the low signal-to-noise ratio, that have been a challenge for scientists since the setting of this scientific field: Nuclear Astrophysics. In the last two to three decades, experimental improvements, including the construction of underground laboratories, allowed for the first time the measurement of cross-sections of astrophysical nuclear processes in the relevant energy region for astrophysics. Also, indirect methods were developed. As a general and common feature, using these methods it is possible to relate the features --typically the cross-section-- of a process that is experimentally simpler to measure, although not directly linked to astrophysics, to those of another process that is of interest for this latter field. This didactic paper will briefly describe some of these indirect methods with a special emphasis on Trojan Horse and on its application also to reactions that involve the use of radioactive ion beams and to neutron-induced reactions.

Reaction measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

Reprint of: Reaction measurements with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas jet target

Prof. Claudio Spitaleri, director of the schoolIt is my pleasure, as co-director of the school, to welcome students and lecturers of the “Eigth European Summer School on Experimental Nuclear Astrophysics”. The school is at its seventh edition and we have students coming from several European countries and from all the world, like Lebanon, India, USA, Russia, Canada, Japan, China, Brazil, Kazakhstan. This is a clear sign that the school is considered as an important meeting for the international Nuclear Astrophysics Community worldwide. We are very proud to offer, for the eigth time, our school program, which aims at widening the students’ perspectives and sets, hopefully, a milestone in the education of a new generation of scientists. I remind you that among the goals of the school there are two particular points that deserve attention. The first is allowed by the special venue of the school: the program takes place inside a unique building and this allows all the students to continue their scientific activity and the discussions on the lectures beyond the normal lecture hours. The second peculiar feature is that of favouring cultural exchanges between lectures and students with different traditions, customs and religions. Indeed, Sicily has been historically considered as a meeting place for different cultures, a land that offer chances for peaceful and constructive encounters among different peoples.I wish to thank all the supporting institutions and sponsors, such as INFN - LNS and the University of Catania. To you all I wish a pleasant and fruitful time in our wonderful city.Dr. Giacomo Cuttone, Director of INFN-LNSAs a nuclear physicist and as the Director of the LNS it is a pleasure to welcome the students and lecturers of the school in our laboratory. For the eigth time Catania assumes the role of an attraction point in the field of Nuclear Astrophysics, since the whole scientific world is represented here. As a scientist I wish you a fruitful attendance and especially to the youngest ones I wish for them to maintain for all their lifetimes the same enthusiasm they show in this moment. The human understanding of the Universe needs also your efforts as Nuclear Astrophysicists to proceed. LNS has an important and active group of Nuclear Astrophysics research and constitutes a leading facility worldwide in this field. I wish you a fruitful and pleasant week in Santa Tecla and Catania.

Nuclear astrophysics is an interdisciplinary field at the border between nuclear physics and astrophysics. It aims at answering fundamental questions such as how and where are elements synthesised, how energy is generated in stars and how stars evolve and eventually die. Nuclear astrophysics experiments use Earth-bound facilities to investigate nuclear reactions and nuclear properties of interest in stellar scenarios. This review will focus in particular on thermonuclear reactions occurring in relatively low temperature scenarios (T < 1 GK) such as quiescent burning stars and classical novae. Because of the hindering effect of the Coulomb repulsion between nuclei, nuclear cross sections in these scenarios can be extremely small (10−12 barn and even lower) and the signals produced can be challenging to disentangle from the natural background on the Earth’s surface.Moving underground to reduce the background induced by cosmic rays is one possible solution to this problem. For more than 20 years, the LUNA experiment has studied nuclear reactions employing accelerators based deep underground in the Gran Sasso Laboratory in Italy. In this review, recent results obtained at LUNA, as well as future prospects at the new LUNA-MV accelerator, soon to be installed underground will be reviewed.Another possible approach is to employ indirect methods to probe nuclear properties of astrophysical interest. This review work will mention in particular the novel possibility of carrying out nuclear astrophysics experiments at the newly commissioned CRYRING storage ring in GSI, Germany.

The fifth edition of the bi-annual 'Nuclear Physics in Astrophysics (NPA)' conference series was held in Eilat, Israel on April 3–8, 2011. This Conference is also designated as the 24th Nuclear Physics Divisional Conference of the EPS. The main purpose of this conference, as that of the four previous ones in this series, is to deal with those aspects of nuclear physics that are directly related to astrophysics. The concept of such a meeting was conceived by the Nuclear Physics Board of the European Physical Society in 1998. At that time, the idea of such a conference was quite new and it was decided that this meeting would be sponsored by the EPS. The first meeting, in January 2001, was planned and organized in Eilat, Israel. Due to international circumstances the conference was moved to Debrecen, Hungary. Subsequent conferences were held in Debrecen again, in Dresden, Germany, and in Frascati, Italy (moved from Gran Sasso due to the tragic earthquake that hit the L'Aquila region). After 10 years the conference finally returned to Eilat, the originally envisioned site.

The Trojan Horse Method(THM) is an important indirect method in experimental nuclear astrophysics. The S(E) factor of a two-body reaction in Gammow energy range related to astrophysics can be extracted from an appropriate three-body reaction measurement above the Coulomb barrier, under the quasi-free reaction condition. The method can overcome the difficulties caused by the Coulomb barrier suppression and the electron screening effect in direct measurement. While no extrapolation is needed, the method can also avoid the uncertainty in the extrapolation process. THM has a wide application in the experimental nuclear astrophysical study, low-energy fusion data measurement, neutron-induced reaction, electron screening effect and other important research fields. After a short introduction of the THM, this paper will focus on some of the most important experimental results in nuclear astrophysics measured by THM recently and the prospect of its future applications. The following key reactions will mainly be discussed: the indirect measurement of the key neutron source reaction \begin{document}$ ^{{\rm{13}}}{\rm{C(\alpha ,n}}{{\rm{)}}^{{\rm{16}}}}{\rm{O}}$\end{document} in the s-process of AGB stars, the indirect measurement of the nuclear reaction related to the fluorine abundance anomaly in AGB stars, as well as the recent hot spot, the indirect measurement results of the carbon burning reaction in medium or massive stars.

▪ Abstract This review summarizes current problems and questions in experimental nuclear astrophysics. It focuses on the present need for experimental data, emphasizing novel methods and approaches. Starting with an overview on nuclear energy generation and nucleosynthesis in an astrophysical plasma, the discussion concentrates on crucial problems related to the various aspects of stellar evolution, from the hydrostatic stage through the advanced burning scenarios up to and including the supernova explosion mechanism. Innovative experimental approaches are needed to pursue the associated questions in stellar nucleosynthesis. Particular emphasis is given to the potential use of radioactive ion beams and their importance for characterizing explosive nucleosynthesis in X-ray bursts and supernovae.