Applications In Nuclear Physics Research Articles

3He proportional counter development for thermal neutron detection

Neutron detection is used in a wide range of applications in nuclear physics, radiation protection, nuclear fuel cycle, reactor instrumentation, security and industrial measurement. Among the detectors used in this field, we notice the gas-filled 3He proportional counters which have been one of the main detecting tools for thermal and cold neutron detection for many years. This last characteristic has ensured that this detector is one of the best tools for thermal neutron flux measurements in a nuclear reactor control. In the instrumentation and detection laboratory of the Nuclear Research Center, of Birine, we are working toward the design and the development of this type of detectors, indeed, several prototypes of neutron detectors have been realized including the 3He proportional counters. Through this paper, we will present the experimental steps and the obtained results to carry out a 3He proportional counter prototype that was fully developed and tested in our laboratory. A comparison study was made between our detector and a commercial cylindrical 3He neutron detector which was considered in this work as a reference detector: LND252 (3He)-PC. The results showed that the characteristics of the gas amplification and the counting plateau for the two counters reference LND 252 (3He)-PC and our prototype was of the same order of scale. The experimental tests show that our developed prototype perfect fit with the standard International Electrotechnical Commission (IEC, www.iec.ch ) in the operating principle, the technology adopted and obtained technical specifications.

Frequency and amplitude modulation of a cw-dye laser for measuring hyperfine frequency separations in optogalvanic spectra of 139La I.

This paper describes frequency modulation of a cw-dye laser to generate a frequency-discriminant dispersive signal by phase-sensitive detection of the optogalvanic signal in a lanthanum hollow cathode lamp. The frequencies of the six major hyperfine components in 5d26s4F9/2 (4121.572cm-1)----→579.13nm⁡5d26p4F9/2(21384.0cm-1) transition in 139La I were measured with an accuracy of 50 MHz, using a calibrated wavemeter after locking the cw-dye laser frequency to the dispersive error signal of the constituent hyperfine component. The measured hyperfine separations are found to be consistent with separations measured using the standard amplitude modulation technique and also with earlier reported results. The relative ease of the optical setup for locking of the cw-dye laser to optogalvanic spectra can be adapted to atomic physics applications for stabilization of laser frequency in the visible region.

Approximate nonlinear wave solutions of the coupled two-component Gross–Pitaevskii equations with spin–orbit interaction

Recent experimental observations of spin–orbit coupling (SOC) in Bose–Einstein condensates (BECs) open the way for investigating novel physics of nonlinear waves with promising applications in atomic physics and condensed matter physics. The interplay between atomic interactions and SOC are crucial for the understanding of the dynamics of nonlinear waves in BECs with SOC. Here, in the small linear coupling regime, an approach is presented which allows us to derive an infinite number of novel approximate solutions of the Gross–Pitaevskii equations (GPEs) in one and two dimensions including SOCs, time-dependent external potentials, and nonlinearities leading to breathers and periodic as well as quasiperiodic nonlinear waves. To verify the theoretical predictions we perform numerical simulations which show for several cases a very good agreement with the analytics. For the case of one spatial dimension, it is shown that functions describing the external potential and nonlinearities cannot be chosen independently. The management of the solutions is clarified along with some important physical properties such as Josephson oscillations and Rosen–Zener oscillations.

Shannon information entropy in the presence of magnetic and Aharanov–Bohm (AB) fields

In this research article, quantum information-theoretic analysis of the class of Yukawa potential (CYP) has been considered in the presence of magnetic and Aharanov–Bohm (AB) fields both analytically. We solve the Schrodinger equation in the presence of external magnetic and AB fields for the CYP via the functional analysis approach to obtain the energy equation and wave function, respectively. The probability density is then obtained by squaring the wave function which is then used to obtain the Shannon entropy numerically. From our results, we note that the all-inclusive effect of the magnetic and AB fields influences the Shannon entropies such that negative values are observed, demonstrating that negative entropies exist which physically means that the probability densities are highly localized in this region. The variation in the Shannon entropy with the screening parameter $$\alpha$$ , magnetic and AB fields for the CYP is discussed. The Bialynicki-Birula, Mycielski inequality (BBM) uncertainty relation is also verified. The content of this research finds application in atomic and molecular physics, quantum chemistry and physics. In this study, Shannon information entropy is investigated with the class of Yukawa potential in position and momentum spaces in the presence of magnetic and Aharanov–Bohm (AB) fields. The all-inclusive effect of the magnetic and AB fields influences the Shannon entropies such that negative values are observed, which physically means that the probability densities are highly localized in this region. The Shannon entropy measure satisfied the Bialynicki-Birula and Mycielski (BBM) uncertainty.

How machine learning conquers the unitary limit

Machine learning has become a premier tool in physics and other fields of science. It has been shown that the quantum mechanical scattering problem cannot only be solved with such techniques, but it was argued that the underlying neural network develops the Born series for shallow potentials. However, classical machine learning algorithms fail in the unitary limit of an infinite scattering length. The unitary limit plays an important role in our understanding of bound strongly interacting fermionic systems and can be realized in cold atom experiments. Here, we develop a formalism that explains the unitary limit in terms of what we define as unitary limit surfaces. This not only allows to investigate the unitary limit geometrically in potential space, but also provides a numerically simple approach towards unnaturally large scattering lengths with standard multilayer perceptrons. Its scope is therefore not limited to applications in nuclear and atomic physics, but includes all systems that exhibit an unnaturally large scale.

Carbon-based innovative materials for nuclear physics applications (CIMA), INFN project

The INFN-CIMA project deals with the employment of graphene, graphene oxide (GO) and reduced graphene oxide (rGO) for applications in Nuclear Physics. In particular, the project aim is that to use the special properties of GO, which can be synthesized as a thin foil with 0.1–100 µm thickness, to realize thin films for solid ion strippers employed in ion accelerator sources with lifetime advantages with respect to the traditional graphite foils. rGO thin foils can be employment to develop laser-generated plasma and to accelerate protons and carbon ions in target-normal-sheath-acceleration (TNSA) regime. The GO can be also employed for the realization of special sensors of temperature, air relative humidity and gas. Moreover, it can be used to realize water-equivalent, biocompatible and low dimensional, dosimeters based on the lecture of the reduction level produced by the absorbed dose. Finally, graphene and rGO films can be applied to investigate the implemantation ofsmall radiation detectors. Many applications and experimental results will be presented and discussed.

Attosecond γ -ray vortex generation in near-critical-density plasma driven by twisted laser pulses

Ultra-short brilliant γ-rays have many potential applications in astrophysics, nuclear physics, and ultra-fast science. However, attosecond γ-ray beams with energy above 100 MeV are still very challenging. Here, we propose and numerically demonstrate an all-optical scheme to produce sub-GeV attosecond γ-rays in near-critical-density (NCD) plasma. When a left-hand circularly polarized Laguerre–Gaussian (LG) laser pulse irradiates the NCD plasma, dense attosecond electron bunches are produced, trapped by the LG laser, and accelerated to GeV energies. Subsequently, these electrons oscillate in the LG laser electric fields and emit a string of hundreds MeV attosecond (367 as) γ-ray pulses. Three-dimensional particle-in-cell simulations indicate that, at a laser intensity of 1022 W/cm2, the yield of γ-ray pulses with photon energies above 1 MeV is as high as 1013 with a peak angular momentum of 10−15 kg m2/s. This results in γ-ray vortex beams with an unprecedented peak brilliance of 1024 photons s−1 mm−2 mrad−2 per 0.1% bandwith at 1 MeV, which may offer a unique opportunity for diverse applications.

Analysis of the neutron noise induced by fuel assembly vibrations

The investigation of neutron noise is key to several applications in nuclear reactor physics, such as the detection of control rod or assembly vibrations and the diagnostic of coolant speed and void fraction. In this paper we will elucidate some aspects of the noise equations in the Fourier domain, for the case of periodic fuel rod vibrations with frequency ω0 in a small symmetrical system in which the perturbation is centrally located. We will in particular focus on the double frequency effect, i.e., the emergence of a noise component at 2ω0 (possibly stronger than the one at the fundamental frequency ω0). Our analysis will be carried out without truncating the noise source at the first order and in the context of a non-perturbative approach (i.e., without resorting to linearization). For this purpose, we will select a simple benchmark configuration that is amenable to accurate reference solutions obtained by solving the exact time-dependent transport equations. The analysis carried out in this work suggests that the non-perturbative noise equations are mandatory in order to properly discriminate the possible emergence of double frequency effects in neutron noise, especially in view of comparing simulation results to experimental data.

Orientational quantum revivals induced by a single-cycle terahertz pulse

The phenomenon of quantum revivals resulting from the self-interference of wave packets has been observed in several quantum systems and utilized widely in spectroscopic applications. Here, we present a combined analytical and numerical study on the generation of orientational quantum revivals (OQRs) exclusively using a single-cycle THz pulse. As a proof of principle, we examine the scheme in the linear polar molecule HCN with experimentally accessible pulse parameters and obtain strong field-free OQR without requiring the condition of the sudden-impact limit. To visualize the involved quantum mechanism, we derive a three-state model using the Magnus expansion of the time-evolution operator. Interestingly, the THz pulse interaction with the electric-dipole moment can activate direct multiphoton processes, leading to OQR enhancements beyond that induced by a rotational ladder-climbing mechanism from the rotational ground state. This work provides an explicit and feasible approach toward quantum control of molecular rotation, which is at the core of current research endeavors with potential applications in atomic and molecular physics, photochemistry, and quantum information science.

Zeno dynamics of quantum chirps

We investigate the Zeno dynamics of quantum chirps. More specifically, we analyze the Zeno dynamics of a chirped solitary wave solution of the non-dimensional nonlinear Schrödinger equation (NLSE) with a gain/loss term. We show that the motion of the quantum chirp can be inhibited by frequent measurements in the observation domain. In order to assess the effect of Zeno dynamics on the quantum chirp imaging resolution, we analyze and compare its point spread functions (PSF) under free evolution and under Zeno dynamics. Additionally, we investigate the effect of observation frequency on the quantum chirp profile as well as on its probability of lingering in the observation domain. Our results can be immediately used to investigate the signal properties of quantum chirps and their possible jamming properties by Zeno dynamics in quantum radar technology. Additionally, many potential applications in atomic physics and optics including nonlinear phenomena and chirps can be investigated using the approach presented in our paper.

The SPES facility at Legnaro National Laboratories

Worldwide efforts to tackle the nature of exotic nuclei comprise the construction of new-generation Radioactive Ion Beam facilities. The Italian community is deeply involved in the process and the construction of SPES at Legnaro National Laboratories (INFN) is progressing. This contribution describes the layout of SPES in all its flavours, from Nuclear Physics to Applications in Nuclear Medicine and Neutron Physics. In particular, the status of the SPES-β ISOL facility, together with some of the relevant physics cases and the associated equipment are described.

IAEA activities in support of nuclear physics research and applications

Facilitation of development and promotion of nuclear applications for peaceful purposes and related capacity building are among the IAEA missions where Physics Section contributes most. The relevant activities fall under the IAEA’s program ‘nuclear science’ and cover four main thematic areas: applications of particle accelerators, sustainable utilization of research reactors, controlled fusion research and technology, and nuclear instrumentation. The Section also operates the Nuclear Science and Instrumentation Laboratory (NSIL) at Seibersdorf, located approximately 40 km south of Vienna. NSIL’s primary mission is to assist IAEA Member States to establish, operate and maintain various nuclear instrumentation and spectrometry-based techniques in support of a wide range of applications such as materials This paper will illustrate through a number of selected examples how the IAEA supports nuclear physics research and diverse applications in order to address key development priorities in many areas of societal importance and economic growth of the developing countries. In addition, some future plans on enhancing capabilities of the Nuclear Science and Instrumentation Laboratory as part of Physics Section will be highlighted, in particular by establishment of the neutron science facility and considerations for a compact ion beam accelerator.

Virial expansion of attractively interacting Fermi gases in one, two, and three dimensions, up to fifth order

The virial expansion characterizes the high-temperature approach to the quantum-classical crossover in any quantum many-body system. Here, we calculate the virial coefficients up to the fifth-order of Fermi gases in 1D, 2D, and 3D, with attractive contact interactions, as relevant for a variety of applications in atomic and nuclear physics. To that end, we discretize the imaginary-time direction and calculate the relevant canonical partition functions. In coarse discretizations, we obtain analytic results featuring relationships between the interaction-induced changes $\Delta b_3$, $\Delta b_4$, and $\Delta b_5$ as functions of $\Delta b_2$, the latter being exactly known in many cases by virtue of the Beth-Uhlenbeck formula. Using automated-algebra methods, we push our calculations to progressively finer discretizations and extrapolate to the continuous-time limit. We find excellent agreement for $\Delta b_3$ with previous calculations in all dimensions and we formulate predictions for $\Delta b_4$ and $\Delta b_5$ in 1D and 2D. We also provide, for a range of couplings,the subspace contributions $\Delta b_{31}$, $\Delta b_{22}$, $\Delta b_{41}$, and $\Delta b_{32}$, which determine the equation of state and static response of polarized systems at high temperature. As a performance check, we compare the density equation of state and Tan contact with quantum Monte Carlo calculations, diagrammatic approaches, and experimental data where available. Finally, we apply Pad\'e and Pad\'e-Borel resummation methods to extend the usefulness of the virial coefficients to approach and in some cases go beyond the unit-fugacity point.

Stimulated Raman adiabatic passage: Effects of system parameters on population transfer

The stimulated Raman adiabatic passage (STIRAP) procedure is a robust and complete population transfer method which has various applications in chemistry and atomic physics. The bright-state STIRAP (b-STIRAP) is an alternative population transfer process with an intuitive pulse sequence. The simultaneous use of both STIRAP and b-STIRAP is beneficial in quantum manipulation. Adjusting the system parameters in both processes can be useful for the enhancement of transfer efficiency. Hence, we have studied the effects of single-photon detuning, transition time, pulse width, and pulse delay parameters on the population transfer via STIRAP and b-STIRAP techniques. Moreover, the impact of the field amplitude is investigated and analyzed in the b-STIRAP method. It is shown that the robustness of the complete transition can be improved by tuning the field amplitude in the single-photon resonance condition.

Weyl's problem: A computational approach

The distribution of eigenvalues of the wave equation in a bounded domain is known as Weyl's problem. We describe several computational projects related to the cumulative state number, defined as the number of states having wavenumber up to a maximum value. This quantity and its derivative, the density of states, have important applications in nuclear physics, degenerate Fermi gases, blackbody radiation, Bose–Einstein condensation, and the Casimir effect. Weyl's theorem states that, in the limit of large wavenumbers, the cumulative state number depends only on the volume of the bounding domain and not on its shape. Corrections to this behavior are well known and depend on the surface area of the bounding domain, its curvature, and other features. We describe several projects that allow readers to investigate this dependence for three bounding domains—a rectangular box, a sphere, and a circular cylinder. Quasi-one- and two-dimensional systems can be analyzed by considering various limits. The projects have applications in statistical mechanics, but can also be integrated into quantum mechanics, nuclear physics, or computational physics courses.

An ultra-compact x-ray free-electron laser

In the field of beam physics, two frontier topics have taken center stage due to their potential to enable new approaches to discovery in a wide swath of science. These areas are: advanced, high gradient acceleration techniques, and x-ray free electron lasers (XFELs). Further, there is intense interest in the marriage of these two fields, with the goal of producing a very compact XFEL. In this context, recent advances in high gradient radio-frequency cryogenic copper structure research have opened the door to the use of surface electric fields between 250 and 500 MV m−1. Such an approach is foreseen to enable a new generation of photoinjectors with six-dimensional beam brightness beyond the current state-of-the-art by well over an order of magnitude. This advance is an essential ingredient enabling an ultra-compact XFEL (UC-XFEL). In addition, one may accelerate these bright beams to GeV scale in less than 10 m. Such an injector, when combined with inverse free electron laser-based bunching techniques can produce multi-kA beams with unprecedented beam quality, quantified by 50 nm-rad normalized emittances. The emittance, we note, is the effective area in transverse phase space (x, p x /m e c) or (y, p y /m e c) occupied by the beam distribution, and it is relevant to achievable beam sizes as well as setting a limit on FEL wavelength. These beams, when injected into innovative, short-period (1–10 mm) undulators uniquely enable UC-XFELs having footprints consistent with university-scale laboratories. We describe the architecture and predicted performance of this novel light source, which promises photon production per pulse of a few percent of existing XFEL sources. We review implementation issues including collective beam effects, compact x-ray optics systems, and other relevant technical challenges. To illustrate the potential of such a light source to fundamentally change the current paradigm of XFELs with their limited access, we examine possible applications in biology, chemistry, materials, atomic physics, industry, and medicine—including the imaging of virus particles—which may profit from this new model of performing XFEL science.

A Dual-Frequency Faraday Laser

The Faraday laser, with Faraday anomalous dispersion optical filter (FADOF) as frequency-selection element, is a natural narrow-bandwidth light source for laser physic experiments. In this work, a dual-frequency (DF) Faraday laser is demonstrated for the first time on Cs D2 line at 852 nm. The frequencies of the two modes of DF Faraday laser hinge on the peak transition frequencies of 852 nm FADOF transmittance spectrum corresponding to the ground state F=4 and F=3. The frequency difference between the two modes is tunable over a range of 1.4 GHz with the temperature of Cs vapor cell inside the FADOF. The linewidth of each laser mode is less than 33 kHz. Furthermore, the most probable linewidth of the beat-note spectra between the two modes is 902.95 Hz at different vapor-cell temperatures. Such a DF Faraday laser has many potential applications in atomic physics, such as sub-Doppler spectroscopy and coherent population trapping atomic clocks.

Dynamics of Bose-Einstein Condensates Subject to the Pöschl-Teller Potential through Numerical and Variational Solutions of the Gross-Pitaevskii Equation.

We present for the first time an approach about Bose–Einstein condensates made up of atoms with attractive interatomic interactions confined to the Pöschl–Teller hyperbolic potential. In this paper, we consider a Bose–Einstein condensate confined in a cigar-shaped, and it was modeled by the mean field equation known as the Gross–Pitaevskii equation. An analytical (variational method) and numerical (two-step Crank–Nicolson) approach is proposed to study the proposed model of interatomic interaction. The solutions of the one-dimensional Gross–Pitaevskii equation obtained in this paper confirmed, from a theoretical point of view, the possibility of the Pöschl–Teller potential to confine Bose–Einstein condensates. The chemical potential as a function of the depth of the Pöschl–Teller potential showed a behavior very similar to the cases of Bose–Einstein condensates and superfluid Fermi gases in optical lattices and optical superlattices. The results presented in this paper can open the way for several applications in atomic and molecular physics, solid state physics, condensed matter physics, and material sciences.

Nobel Prize Level Scientific Discoveries of a Heir of Zaporizhian Cossacks

In this work, three fundamental discoveries of the Ukraine-born Prof. George A. Gamow are presented from a single scientific and methodological point of view. Each of them is truly worth of the Nobel Prize – the most prestigious recognition of achievements of a scientist.
 We trace the emergence of G. Gamow as one of the most outstanding scientists of the twentieth century – encyclopaedist, theoretical physicist by heart, astrophysicist and biophysicist, talented and brilliant popularizer of science, whose works are readable in one go, as well as the author of unforgettable pranks and jokes.
 
 Gamow was a Fellow of the Danish Royal Academy of Sciences, the American Academy of Arts and Sciences, the International Astronomical Union, the American Physical Society, an honorary doctor of countless universities. Although his name is little known in Ukraine, the history of science would be incomplete without him.
 
 From an early age G. Gamow has shown a great interest in scientific research, using a microscope to look for erythrocytes and a telescope to observe the Halley comet. He graduated from the Faculty of Physics and Mathematics of Leningrad State University, where he followed classes of Professor O. Friedman, founder of the evolutionary cosmology. He has undergone training at the University of Goettingen, the center of theoretical physics at the time, worked for Nobel Prize winners Professors E. Rutherford and N. Bohr. At the age of 28, G. Gamow, by the recommendation of academician V. Vernadskyi, became the member of the Academy of Sciences of USSR, the youngest member in the entire history of its existence.
 Throughout his life, G. Gamow was interested in the fundamental scientific problems and made numerous world-class discoveries that are written by golden letters in the treasury of the human civilization. He has found explanation to the E. Rutherford’s experiments with alpha particles (tunnelling effect); introduced the empirical formula of Geiger – Nettoll, connecting the energy of alpha particles to the half-life of radioactive nuclei. G. Gamow is one of the pioneers of the liquid-drop model of a nucleus, and the application of nuclear physics to the evolution of stars. He proposed a fantastic hypothesis about the early universe, suggesting it being not only super dense but also very hot. He also built the Big Bang theory, which led to the existence of relic radiation (space microwave background) with the characteristic temperature of 5–7 degrees above the absolute zero, detected by methods of radio astronomy. He proposed a triplet model of the genetic code - the alphabet of life with three-letter words, experimentally proven by X-ray structural studies of DNA and empirically established rules of E. Chargaff. These discoveries have greatly contributed not only to the development of the modern science, but to the industrial and economic expansion of humanity.

Temporally stable rotational coherent states for molecular simulations. I. Spherical and linear rotor cases.

We reformulate a previous rotational coherent state (CS) to obtain temporally stable (TS) CSs for the spherical rotor (SR) and linear rotor (LR): TSSR and TSLR CSs, respectively. Being TS, the new CSs remain within their own classes during dynamics by evolving exclusively through their CS parameters. The new TS CSs are now appropriate to reconstruct quantum rotational properties from classical-mechanics simulations of chemical reactions. Following literature precedents, we enforce temporal stability by incorporating action-angle-related phase factors into the parameters of the original CS. In addition, to elucidate CS quantum reconstruction procedures, we derive one more rotational CS from a quantum electron nuclear dynamics description of a diatomic rotor (DR). The DR CS and the TSLR CS are not identical but display similar structures and properties. We rigorously demonstrate and examine the key properties of the three CSs: continuity, resolution of unity, temporal stability, action identity, minimum uncertainty relationships, and quasi-classical behavior. Finally, we present computer simulations of the CSs dynamics and an application of them to predict CO rotational excitation probabilities in the Li+ + CO reaction. CS results agree satisfactorily with experimental ones and encourage future applications in chemical dynamics, statistical mechanics, spectroscopy, nuclear physics, quantum coherence, and quantum computing.