Charged-particle Nuclear Reactions Research Articles

Evaluation of differential cross-sections for light element reactions at low energies using R-matrix calculations: The case of 12C

The theoretical evaluation of diÆerential cross-section values for low-energy re- actions of light elements is of great importance in the fields of IBA (Ion Beam Analysis) and nuclear astrophysics. R-matrix theory is generally accepted as the most appropriate one for the analysis of resonance reactions in low-energy nuclear physics. In this approach, the configuration space of the scattering problem is divided into an internal region, corresponding to the compound nucleus, where the total wave function can be expanded into a complete set of eigenstates (in terms of unknown base functions, with the energy eigenvalues and the matrix elements of the base functions being adjustable parameters) and an external region, where the possible combinations of coupled particle pairs exist, corresponding to the reaction channels that emerge from the compound nucleus. This division of space is made by the choice of the boundary of the compound nucleus, i.e. an appropriate nuclear radius is chosen for each reaction channel. The R-matrix takes account of all the interactions which occur inside the nucleus. In the present work, results obtained in the specific case of elastic scattering and charged-particle nuclear reactions, namely for the 12C+p system are presented.

Generating keV ion distributions for nuclear reactions at near solid-density using intense short-pulse lasers

Our understanding of a large range of astrophysical phenomena depends on a precise knowledge of charged particle nuclear reactions that occur at very low rates, which are difficult to measure under relevant plasma conditions. Here, we describe a method for generating dense plasmas at effective ion temperatures >20 keV, sufficient to induce measurable charged particle nuclear reactions. Our approach uses ultra-intense lasers to drive micron-sized, encapsulated nanofoam targets. Energetic electrons generated in the intense laser interaction pass through the foam, inducing a rapid expansion of the foam ions; this results in a hot, near-solid density plasma. We present the laser and target conditions necessary to achieve these conditions and illustrate the system performance using three-dimensional particle-in-cell simulations, outline potential applications and calculate expected nuclear reaction rates in the D(d,n) and 12C(p,γ) systems assuming CD, or CH aerogel foams.

Numerical Study of Fusion Cross Sections for 12C+12C and 16O+16O Reactions by Using Wong Formula

The height of the barrier between the interacting nuclei is one of the interesting topics in nuclear reaction, especially in charged-particle nuclear reactions. Wong formula is one method that can be used to perform such study, especially about fusion cross section. Therefore, a study about fusion cross sections of some light nuclei with Wong formula becomes very interesting to be performed. In this study, the fusion cross sections of 12C+12C and 16O+16O reactions have been calculated by using Wong formula at 12<=E<=32 MeV of energies. The potential of the interacting nuclei was approached by using Woods-Saxon potential. The calculations performed numerically by using both finite different and Nelder-Mead methods. The obtained results of this study have achieved a good agreement with the experimental results and the calculation results of the other researchers. Those results were indicated that Wong formula has good capability in explaining the experimental results concerning fusion cross section of light nuclei.

Screened thermonuclear reactions and predictive stellar evolution of detached double-lined eclipsing binaries

The low energy fusion cross sections of charged-particle nuclear reactions (and the respective reaction rates) in stellar plasmas are enhanced due to plasma screening effects. We study the impact of those effects on predictive stellar evolution simulations for detached double-lined eclipsing binaries. We follow the evolution of binary systems (pre-main sequence or main sequence stars) with precisely determined radii and masses from 1.1Mo to 23Mo (from their birth until their present state). The results indicate that all the discrepancies between the screened and unscreened models (in terms of luminosity, stellar radius, and effective temperature) are within the observational uncertainties. Moreover, no nucleosynthetic or compositional variation was found due to screening corrections. Therefore all thermonuclear screening effects on the charged-particle nuclear reactions that occur in the binary stars considered in this work (from their birth until their present state) can be totally disregarded. In other words, all relevant charged-particle nuclear reactions can be safely assumed to take place in a vacuum, thus simplifying and accelerating the simulation processes.

Dense plasma effects on nuclear reaction rates.

Plasma density effects can cause an exponential change in charged particle nuclear reaction rates important in stellar evolution. Reaction rates in dense plasma, with emphasis on quantum aspects, are examined here using path integral Monte Carlo calculations. Quantum mechanics causes a reduction in the many body enhancement of the reaction rate compared to the value for a classical system. This can be attributed to the "quantum smearing" of the short range Coulomb interaction resulting in reduced repulsion between the reacting pair and surrounding particles. Electron screening and ion exchange effects are also examined, with screening reducing and exchange slightly increasing the many body enhancement.

Development of Nuclear Reaction Data Retrieval System on Meme Media

A newly designed retrieval system of charged particle nuclear reaction data is developed on Meme media architecture. We designed the network-based (client-server) retrieval system. The server system is constructed on a UNIX workstation with a relational database, and the client system is constructed on Microsoft Windows PC using an IntelligentPad software package. The IntelligentPad is currently available as developing Meme media. We will develop the system to realize effective utilization of nuclear reaction data: I. “Re-production, Re-edit, Re-use”, II. “Circulation, Coordination and Evolution”, III. “Knowledge discovery”.

Development of a charged-particle nuclear reaction data retrieval system on Intelligent Pad: CONTIP

A newly designed retrieval system of charged-particle nuclear reaction data (CPND) is developed on the IntelligentPad architecture. NRDF (Nuclear Reaction Data File), which is a kind of CPND compilation, is applied as an example. The authors designed the network-based (client-server) retrieval system. The server system is constructed on a UNIX workstation with a relational database; the client system is built on a Microsoft Windows PC using an IntelligentPad software package. The system is called CONTIP, which is an abbreviation of ‘Creative, Cooperative and Cultural Objects for Nuclear data and Tools on IntelligentPad’. CONTIP will be developed to realise effective utilisation of nuclear reaction data: (i) reproduction, re-edit, reuse, (ii) circulation, coordination and evolution and (iii) knowledge discovery.

Development of a charged-particle nuclear reaction data retrieval system on IntelligentPad: CONTIP

Development of a charged-particle nuclear reaction data retrieval system on IntelligentPad: CONTIP

Comparison of elastic and non-elastic displacement damage under light ion simulation irradiation

In order to simulate fusion neutron displacement damage, irradiations with light ions can be used. For this purpose irradiations of iron with protons and α-particles were experimentally and theoretically investigated. The main emphasis was put on the behavior of displacement damage production caused by high-energetic recoils induced by charged particle nuclear reactions. Evaluation of excitation functions and mean recoil ranges lead to non-elastic PKA-spectra. The comparison between charged particle and fusion neutron induced PKA-spectra points out, that the charged particle-induced non-elastic fraction contributes a considerable part to the PKA-spectra. The closest fit was found for the 20 MeV proton-induced PKA-spectrum. Further comparisons of DPA-data show, that at the highest examined energies the non-elastic/total DPA-ratio is 0.43 for protons and 0.47 for α-particles.

Investigation of the charged particle nuclear reactions on natural boron for the purposes of the thin layer activation (TLA)

Boron of natural composition was investigated in the form of NiBSi metallic-glass foil to determine the cross-section functions of the natB(p,x) 7Be and the natB(d,x) 7Be nuclear reactions. These reactions are very important from the point of view of Thin Layer Activation (TLA) technique to monitor the wear of boron-containing superhard materials (e.g. BN), because the 7Be with its half-life of 53 d and gamma-energy of 447 keV is very suitable for wear measurements. The possibility of recoil-implantation of the radioactive nuclei was also studied.

Parity violation in charged particle nuclear reactions.

The potential role of charged particle resonance reactions in the study of parity nonconservation (PNC) in the nucleus is examined in light of recent statistical interpretations of PNC measurements in neutron resonances. Several PNC observables have been calculated using experimental resonance parameters for five s-d shell nuclei. Longitudinal analyzing powers in (p\ensuremath{\rightarrow},${\mathrm{\ensuremath{\alpha}}}_{0}$) reactions show strong dependence on energy, angle, and resonance parameters. Measurements of analyzing powers at the ${10}^{\mathrm{\ensuremath{-}}4}$ level should provide new information on parity vaiolation in the nucleon-nucleus interaction.

ANALNRA — charged particle nuclear reaction analysis software for the IBM PC

Nuclear reaction analysis (NRA) is a powerful ion beam technique which can only be fully harnessed with suitable analysis software. ANALNRA is a NRA analysis package written for situations when the incident and exiting ions are isotopes of hydrogen and helium. This includes (p, α), (d, p), (d, α), ( 3He, p) and ( 3He, α) reactions that are used for analysis of many light elements including C, O, F and Al. The package optimises a suitably parameterized distribution of up to five isotopes using nonlinear least squares fitting. The package is written for the IBM PC in Turbo C and uses EGA and VGA graphical interfaces to overlay initial guess and final fits to the raw spectral data.

Subject index

This chapter discusses the neutron sources. All neutron sources are based on nuclear reactions that free neutrons bound in nuclei. These are categorized according to the mechanisms by which this is done: fission chain reactions, fusion reactions, e--bremsstrahlung-induced photoneutron and photofission reactions, charged-particle nuclear reactions, and spallation. The last three together termed as accelerator-based reactions. Muon-catalyzed fusion and the neutron focus represent other categories of neutron-producing reactions. Electron-bremsstrahlung sources produce evaporation neutrons with an average energy of a few mega-electron-volts, whether due to photofission or photonuclear reaction. Since the neutron production mechanisms involve first producing bremsstrahlung photons, which then interact to produce neutrons, these sources produce very large gamma-ray fluxes as well, which sometimes represent a troublesome background. Neutron shielding is like that for a reactor. Spallation sources also produce predominantly evaporation neutrons, which boil off in the process of “cooling off” of highly excited nuclei. The types of accelerators that provide the highest intensities are resonant accelerators, which all have inherent pulse structure. In cyclotrons, synchrotrons, and storage rings, bunches of particles circulate at frequencies of a few megahertz.

Low energy charged particle nuclear reaction studies with SSNTDs

In experimental nuclear reaction studies the most general requirement is to measure the yield and the spatial distribution of the reaction products, while their energy and type are simultaneously determined, frequently in the presence of a high background due to various types of radiation. Especially in studying low-yield nuclear processes, high efficiency and long-term stability of the applied spectroscopic method are highly desirable. In such situations, various nuclear track detection methods can be used very advantageously and successfully. Some of these methods are briefly discussed and examples are presented from our results concerning the application of nuclear track spectroscopy to different low-energy nuclear reaction studies, angular distribution and excitation function measurements.

Data Base of Charged Particle Nuclear Reaction : NRDF

Data Base of Charged Particle Nuclear Reaction : NRDF

An information management system for charged particle nuclear reaction data

A storage and retrieval system for Charged Particle Nuclear Reaction Data (CPND) has been designed and implemented. CPND is a typical case of raw data produced in scientific research activities. The system has the architecture of an inter mediate system which lies between an IR system and a Data Base Management System (DBMS). Data input to the system are coded by a "data language" of free format. A doubly inverted file structure is incorporated into the system for both information representation and indexing. The implications of this system in the context of scientific information systems in general is discussed.

Interaction Barrier in Charged-Particle Nuclear Reactions

Simple expressions are obtained for the total reaction cross section in terms of the interaction barrier for the $s$ wave. These expressions allow the interaction barrier to be determined experimentally. Analysis of experimental data for heavy ions on $^{238}\mathrm{U}$ shows that the effective radius parameter decreases as projectile charges increase.

Analyse par reaction nucleaire de l'oxygene et du carbone en couche mince a la surface des metaux Précautions à prendre lors des mesures sur des cibles solides de carbone

Zusammenfassung A preliminary study has been made to define valid experimental conditions in order to determine the quantity of oxygen and carbon, retained by adsorption or chemical reaction, at the surface of high purity metals. A method of analysis by charged-particle nuclear reactions was applied. The first experimental results are given for aluminium metal. These results are compared to those, obtained by one of us, for the same samples, using the activation analysis technique with 2 MeV tritons. In a later paper, we shall report on our results with other metals.

A new broad range spectrometer with a uniform-field sectorial magnet and a preceding quadrupole-magnet doublet

Theoretical basis of constructing a high-resolution and high-transmission spectrometer of a broad range type for charged-particle nuclear reactions is given by the use of a uniform-field sectorial magnet and a preceding quadrupole-magnet doublet. Formulae for various ion-optical parameters in the spectrometer are obtained. The parameters are given as the explicit functions of fractional momentum changes over a range of ±10%. The spectrometer can analyse and detect particles over an energy range from E max to 0.67 E max. The application of a quadrupole-magnet doublet does not only increase the solid angle but also improve the momentum resolution. Applying our theory to a practical example, a product-particle spectrometer is designed for the 55 MeV proton beam which is available by a synchrocyclotron in our Institute for Nuclear Study. An energy resolution of 0.1% and a solid angle of 3×10 −3 steradian can be obtained in the above-mentioned energy range.

Magnetic spectrographs and beam analyzers

A brief discussion is given of some of the magnetic spectrographs and spectrometers in use today for studies of charged-particle nuclear reactions. The need for new instruments with improved resolving power, higher accuracy, larger solid angle, and better signal-to-background ratio is acknowledged. Possible improvements in the design of time-tested spectrographs and beam analyzers, as well as entirely new approaches, are discussed.