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The role of entrance channel parameters such as Z²∕A, charge asymmetry αz, mass-asymmetry (ηA), charge product (Z1Z2subscript>), mean fissility Xm, Coulomb interaction parameter and (N-Z)-(N-Z) on compound nucleus formation of actinide nuclei using heavy ion fusion reactions were investigated. For the formation of compound nuclei, the considered atomic number range of the projectile varies between 5 ≤ Z ≤ 14 and the mass number lies between 10 ≤ 𝐴 ≤ 34. Similarly, the studied target atomic number varies between 78 ≤ Z ≤ 92 and the mass number range is 197 ≤ A ≤ 238. Among these entrance channel parameters, PCN is more systematic for (N-Z)(N+Z), Z²∕A and az. In addition to entrance channel parameters, the Ecm and Ebas also play a significant role in the prediction of PCN. The proposed empirical formulae are applicable to the compound nuclei from Fr to Sg. These findings are significant for the PCN prediction from Fr to Sg. [ABSTRACT FROM AUTHOR] more...

In this work, we delved into the intriguing realm of nuclear physics by investigating fusion reactions initiated by 7 0 Zn projectiles colliding with various stable isotopes of thorium nuclei, including 2 2 7 − 2 3 2 , 2 3 4 Th. Our primary objective was the synthesis of the superheavy element Z = 1 2 0. To achieve this, we employed an advanced statistical model to evaluate the evaporation residue cross-sections. Remarkably, we observed that the fusion reaction between 7 0 Zn and 2 3 1 Th exhibited the highest evaporation residue cross-sections, reaching a peak value. Furthermore, the 3n channel within this fusion reaction yielded substantially larger evaporation cross-sections, with a notable value of 0.89 picobarns. The predicted cross-sections fall within the measurable range, making them highly valuable for experimental endeavors aimed at synthesizing the superheavy element Z = 1 2 0. This research not only contributes to our understanding of nuclear reactions but also holds promise for expanding our knowledge of the heaviest elements in the periodic table, potentially opening new frontiers in nuclear science. [ABSTRACT FROM AUTHOR] more...

The 2 6 Mg (n , γ) 2 7 Mg reaction plays a crucial role in the process of nucleosynthesis in stars. It occurs primarily in massive stars during their late evolutionary stages or during explosive events like supernovae. This paper focuses on investigating discrepancies in the ANC values of the 2 6 Mg (n , γ) 2 7 Mg reaction by analyzing experimental angular distributions of 2 6 Mg (d , p) 2 7 Mg using the DWBA, ADWA and CDCC methods for both ground and first excited states. We then use a mirror nucleus procedure to extract information on the ANCs of the ground state 2 6 Si (p , γ) 2 7 P reaction. The Hauser–Feshbach formalism of the statistical Compound Nucleus (CN) model was applied in this study to perform a compound-nucleus analysis of the 2 6 Mg (d , p) 2 7 Mg reaction. The 2 6 Mg (d , p) 2 7 Mg reaction has almost fulfilled the condition of peripherality, which is necessary for understanding the magnitude of the direct reaction contribution. ANCs for the 2 7 Mg → 2 6 Mg + n virtual decay system were obtained. Moreover, according to charge symmetry of mirror nuclei, the square of proton ANC for a 2 7 P → 2 6 Si + p is determined and comparison between the values of the presented ANCs. [ABSTRACT FROM AUTHOR] more...

The question of energy production in stars stimulated an entire generation of young physicists in the 1930s who came to work in this field exploring the fundamentals of quantum and nuclear physics. Their experience and methodologies were essential to the Manhattan Project, facilitating the rapid development of the atomic bomb. The experience and knowledge gained from the Manhattan Project then flowed back to nuclear astrophysics after the war and led to its further development. This paper is motivated by the question that was raised in the film Oppenheimer, which asks whether "a bomb can set the atmosphere on fire?". Seeking an answer requires a close intellectual exchange between the physics of the atomic bomb and the physics of stellar burning; this exchange is the topic of this paper. [ABSTRACT FROM AUTHOR] more...

Abstract The question of energy production in stars stimulated an entire generation of young physicists in the 1930s who came to work in this field exploring the fundamentals of quantum and nuclear physics. Their experience and methodologies were essential to the Manhattan Project, facilitating the rapid development of the atomic bomb. The experience and knowledge gained from the Manhattan Project then flowed back to nuclear astrophysics after the war and led to its further development. This paper is motivated by the question that was raised in the film Oppenheimer, which asks whether “a bomb can set the atmosphere on fire?”. Seeking an answer requires a close intellectual exchange between the physics of the atomic bomb and the physics of stellar burning; this exchange is the topic of this paper. more...

The sub-barrier fusion hindrance has been observed in the domain of very low energies of astrophysical relevance. The measured fusion cross sections can be well estimated by using formula obtained by folding a Gaussian function for barrier height distribution with the expression for classical fusion cross section for fixed barrier. The parameters of the formula vary smoothly implying its usage in estimating the excitation function. In the present work, the effects of deformation and transfer on fusion reactions have been studied and the absence of neutron transfer channels has been correlated to the hindrance in heavy-ion fusion reactions. [ABSTRACT FROM AUTHOR] more...

Neutron production in high-energy-density plasma is an interesting topic for developing thermonuclear sources of neutrons and hybrid reactors. The promising candidate reactions for thermonuclear fusion (thermonuclear sources of neutrons) are T(d, n)4He and D(d, n)3He (D‑T and D‑D reactions). As T is a radioactive material, fusion experiments in all over the world deal with the D‑D reaction by using nuclear fuel in the form of plastic material such as CD or CD2. Consequently, reactions of deuterium and carbon effectively participate in the neutron yield. In this work, the neutrons flux of the nuclear reactions D(d, n)3He and D(12c, n)13N were simulated using the MCUNED Code in high-energy-density plasma produced by an ultra-high-power laser. Neutrons have been produced using nuclear fuels D2, CD, and CD2. Neutron flux has been calculated per kW of the laser energy expended in the fuel. Deuteron and proton fluxes have been calculated under the same energy conditions. The obtained data for the reactions D(d, n)3He and D(12c, n)13N were compared with each other and with the available experimental data. A computer program, NJOY, has been used to calculate cross section in Acer format to be used by MCUNED. The neutrons flux peak was increased inside the source and magnet cells for CD and CD2 due to adding carbon to the deuterium fuel. These values were decreased in the cells outside the source. The total neutron yields were approximately the same for D2, CD, and CD2 fuels in the air cells outside the source. [ABSTRACT FROM AUTHOR] more...

The hindrance in fusion of heavy-ion reactions crops up in the region of extreme sub-barrier energies. This phenomenon can be analyzed effectively using an uncomplicated straightforward elegant mathematical formula gleaned presuming diffused barrier with a Gaussian distribution. The mathematical formula for cross section of nuclear fusion reaction has been obtained by folding together a Gaussian function representing the fusion barrier height distribution and the expression for classical cross section of fusion assuming a fixed barrier. The variation of fusion cross section as a function of energy, thus obtained, describes well the existing data on sub-barrier heavy-ion fusion for lighter systems of astrophysical interest. Using this simple formula, an analysis has been presented from 16 O + 18 O to 12 C + 198 Pt, all of which were measured down to < 10 μ b. The agreement of the present theoretically calculated estimates with the measured values is excellent. The relatively smooth variation of the three parameters of this formula implies that it may be exploited to estimate the excitation function or to extrapolate cross sections for pairs of interacting nuclei which are yet to be measured. Possible extensions of the present methodology and its limitations have also been discussed. [ABSTRACT FROM AUTHOR] more...

The measured D-D neutron rate of neutral beam heated JET baseline and hybrid H-modes in deuterium is found to be between approximately 50% and 100% of the neutron rate expected from the TRANSP code, depending on the plasma parameters. A number of candidate explanations for the shortfall, such as fuel dilution, errors in beam penetration and effectively available beam power have been excluded. As the neutron rate in JET is dominated by beam-plasma interactions, the 'neutron deficit' may be caused by a yet unidentified form of fast particle redistribution. Modelling, which assumes fast particle transport to be responsible for the deficit, indicates that such redistribution would have to happen at time scales faster than both the slowing down time and the energy confinement time. Sawteeth and edge localised modes are found to make no significant contribution to the deficit. There is also no obvious correlation with magnetohydrodynamic activity measured using magnetic probes at the tokamak vessel walls. Modelling of fast particle orbits in the 3D fields of neoclassical tearing modes shows that realistically sized islands can only contribute a few percent to the deficit. In view of these results it appears unlikely that the neutron deficit results from a single physical process in the plasma. more...

In magnetic fusion experiments, the cross sections for the D-T and D- ^3 He fusion reactions are increased by as much as 50% if the fuel remains spin polarized parallel to the magnetic field. The goal of this study is to assess the feasibility of lifetime measurements of spin polarization, in magnetic fusion relevant conditions, on the DIII-D tokamak using relative changes in charged fusion product (CFP) loss measurements that depend upon the differential fusion cross section d σ /dΩ. Relative measurements that capture changes in the escaping CFP pitch, poloidal, and energy distributions are studied in two realistic TRANSP calculated plasma scenarios: (a) vector-polarized ^3 He and D pellets are injected into a hot hydrogen plasma to produce thermonuclear reactions, and (b) a tensor-polarized deuterium pellet is injected into an L-mode hydrogen background plasma that includes unpolarized ^3 He neutral beam injection. Ideal CFP signals in both scenarios show substantial pitch sensitivity to polarization for 14.7 MeV proton detection at a poloidal angle of $-56^{\circ}$ (on the outer wall in the ion $\nabla B$ direction), and strong sensitivity to polarization for 3.6 MeV alpha flux detection by an array of poloidal detectors. Energy-resolved measurements of 14.7 MeV protons are also sensitive to the degree of polarization for the $-56^{\circ}$ port in the beam-plasma scenario. A realistic assessment of CFP signals in the thermonuclear scenario show count rates in the range of $2\times10^4$ cps for pitch-resolved proton detection and $2\times10^5$ cps for alpha flux measurements. Reduced chi-squared $\chi^{\,2}_\mathrm r$ calculations show polarization lifetime measurements are feasible for either proton or alpha detection of both enhanced or suppressed polarization for the thermonuclear scenario. Measurements of gamma rays produced in the weak $\textrm{D} + {}^{3}\textrm{He} \rightarrow \gamma+ {}^5\textrm{Li}$ branch complement the CFP measurements. more...

Recent Experimental Advanced Superconductivity Tokamak experiments have been dedicated to the studies of increasing ion temperature using Neutral Beam Injection (NBI) in synergy with radio-frequency waves in the Ion Cyclotron Range of Frequencies (ICRFs) in third harmonic. They showed that this scenario effectively accelerates fast deuterium ions and produces a larger tail of fast neutrons with E > 3.0 MeV, as measured by Neutron Energy Spectrum. Comparing to the scenario with 2.2 MW NBI alone, adding an addition of 0.3 MW ICRF power leads to an enhancement of fusion yield by 67% (from ${\text{0}}{{.73 \times 1}}{{\text{0}}^{{\text{14}}}}{\text{ n}}\;{{\text{s}}^{ - {\text{1}}}}$ to ${\text{1}}{{.22 \times 1}}{{\text{0}}^{{\text{14}}}}{\text{ n}}\;{{\text{s}}^{ - 1}}$ ) and an increase of core ion temperature by $\Delta {T_{\text{i}}}\sim 7{\text{80 eV}}$ . Besides, the simulation results of TRANSP show that the neutron yield produced by 0.2 MW ICRF in third harmonic with NBI synergy is roughly consistent with the experimental results. Meanwhile, the 80 keV fast ion tail generated by NBI can be heated up to 400 keV and 600 keV by the 0.2 MW and 1.0 MW ICRF with the synergistic effect, respectively. In addition, it is observed for the first time that this ICRF-NBI synergy leads to the excitation of fishbone instabilities with characteristic frequencies of (10–20) kHz. Furthermore, parameter scans of ICRF/NBI power and plasma density were performed for third harmonic ICRF and NBI synergetic heating schemes. It is found that the neutron yield increases nonlinearly as the ICRF power or plasma density increases. more...

We present a theoretical study of total fusion (TF), complete fusion (CF), and incomplete fusion (ICF) cross sections in the breakup of 9Be (described as n −8Be) projectile on 124Sn, 144Sm and 208Pb target nuclei. We use the continuum discretized coupled-channel formalism together with a sum-rule model, by extending an approach outlined in Mukeru et al. (Nucl. Phys. A 996:121700, 2020) to another weakly bound projectile in different targets. The applicability of the model to incident energies below and around the Coulomb barrier is verified, being confirmed for all three reactions an empirical energy-dependent cutoff angular momentum expression. We show that the TF and ICF cross sections are strongly dependent on the projectile binding energy εb, whereas the CF is weakly affected by that. Despite this weak dependence, the CF contribution to the TF cross section becomes more suppressed by decreasing εb. The dependence of the ICF probability on the breakup threshold is also highlighted. [ABSTRACT FROM AUTHOR] more...

Couplings of a system to other degrees of freedom (that is, environmental degrees of freedom) lead to energy dissipation when the number of environmental degrees of freedom is large enough. Here, we discuss quantal treatments for such energy dissipation. To this end, we discuss two different time-dependent methods. One is to introduce an effective time-dependent Hamiltonian, which leads to a classical equation of motion as a relationship among expectation values of quantum operators. We apply this method to a heavy-ion fusion reaction and discuss the role of dissipation on the penetrability of the Coulomb barrier. The other method is to start with a Hamiltonian with environmental degrees of freedom and derive an equation that the system degree of freedom obeys. For this, we present a new efficient method to solve coupled-channels equations that can be easily applied even when the dimension of the coupled-channels equations is huge. more...

In the present study, I investigate the effect of temperature on fusion cross-sections of the 8 B proton halo projectile. For this purpose, I evaluate two different fusion reactions, 8B + 28Si and 8B +58Ni, in the available literature. I apply two different nuclear potentials as a function of temperature. I calculate both fusion cross-sections and nuclear potentials for both reactions and I then compare the theoretical results with the experimental data. This comparison provides an opportunity for a test of different temperature-dependent potentials in explaining the fusion cross-sections with the 8 B halo nucleus. [ABSTRACT FROM AUTHOR] more...

A novel platform for nuclear physics experiments has been developed on the high-energy, short-pulse OMEGA EP Laser System. Planar foil targets are irradiated with a 10-ps, 1-kJ infrared beam focused to an intensity of the order of 1018 W/cm2. Relativistic electrons generated in the laser–target interaction escape the target, generating a very large electrostatic field, which extracts ions from the target's back surface and accelerates them to MeV energies. The energetic ion flow from the back side of this primary target creates neutrons and charged particles through nuclear reactions in a secondary target placed in the ion flow. Charged-particle detectors were used to measure the energy spectra of the ions. The energy spectrum of the neutrons generated in the secondary target was measured using scintillator-based neutron time-of-flight detectors. First experiments to validate the performance of this setup studied d(d,n)3He and 9Be(d,n)10B reactions. This experimental platform is suitable especially for survey-type studies of nuclear reactions and for reactions that involve rare or radioactive ions like tritium. [ABSTRACT FROM AUTHOR] more...

This tutorial is devoted to the understanding of the different components that are present in the neutron light output pulse height distribution of liquid scintillators in fusion relevant energy ranges. The basic mechanisms for the generation of the scintillation light are briefly discussed. The different elastic collision processed between the incident neutrons and the hydrogen and carbon atoms are described in terms of probability density functions and the overall response function as their convolution. The results from this analytical approach is then compared with those obtained from simplified and full Monte Carlo simulations. Edge effect, finite energy resolution, light output and transport and competing physical processes between neutron and carbon and hydrogen atoms and their impact on the response functions are discussed. Although the analytical treatment here presented allows only for a qualitative comparison with full Monte Carlo simulations it enables an understanding of the main features present in the response function and therefore provides the ground for the interpretation of more complex response functions such those measured in fusion plasmas. Although the main part of this tutorial is focused on the response function to mono-energetic 2.45 MeV neutrons a brief discussion is presented in case of broad neutron energy spectra and how these can be used to infer the underlying properties of fusion plasmas via the application of a forward modelling method. [ABSTRACT FROM AUTHOR] more...

This paper concerns important and difficult problems connected with a design and construction of thermonuclear reactors, which have to use nuclear fusion reactions of heavy isotopes of hydrogen, i.e., deuterium (D) and tritium (T). There are described conditions in which such reactions can occur, and different methods of a high-temperature plasma generation, i.e., high-current electrical discharges, intense microwave pulses, and injection of energetic neutral atoms (NBI). There are also presented experimental facilities which can contain hot plasma for an appropriate period, and particularly so-called tokamaks. The second part presents the technical problems which must be solved in order to build a thermonuclear reactor, that might be used for energetic purposes. There are considered problems connected with a choice of constructional materials for a vacuum chamber, its internal parts, external windings generating a magnetic field, and necessary shields. The next part considers the handling of radioactive tritium; the using of alpha particles (4He) for additional heating of plasma; recuperation of hydrogen isotopes absorbed in the tokamak internal parts, and a removal of a helium excess. There is presented a scheme of a future thermonuclear power plant and critical comments on a road map which should enable the construction of an industrial thermonuclear reactor (DEMO). more...

Up today, two hyper research projects to achieve nuclear fusion energy exist; inertial confinement fusion (ICF) driven by laser, called national ignition facility (NIF) and magnetic confinement fusion the international thermonuclear experimental reactor (ITER) project. In reaching the required temperature and pressure, to ignite nuclear fusion reactor, is technologically complex and economically expensive. Thus, a breakthrough and a short cut, other alternative methods should be considered. Pulsed power ICF driver with repetitive pulse operation, mainly dense plasma focus (DPF) machines for high yield fusion neutrons could be taken as drivers for the fission blanket operation. The setup can be a cost-effective and efficient. In this article, we consider a set of two medium energy sizes DPF to produce simultaneously dense plasma columns, operating as thermonuclear plasma driver, to pierce the pellet target for external nuclear fusion reactions. These DPFs produce sufficient fast neutrons for the fission process in the neutral uranium or thorium and/or weak enriched uranium blanket. The drive systems and the concept for delivering thermonuclear plasma to pellets target in the magnetic free zone of central region will be presented. The feasibility of such fusion-fission hybrid reactor will be discussed. [ABSTRACT FROM AUTHOR] more...

High energy gamma-rays from the 116 Sn + 24 Mg reaction at 23 A MeV were measured using the MEDEA detector at LNS – INFN Catania. Combining this new data with previous measurements yields a detailed view of the quenching of the Giant Dipole Resonance as a function of excitation energy in nuclei of mass A in the range 120 ÷ 132 . The transition towards the disappearance of the dipole strength, which occurs around 230 MeV excitation energy, appears to be remarkably sharp. Current phenomenological models give qualitative explanations for the quenching but cannot reproduce its detailed features. [ABSTRACT FROM AUTHOR] more...