Nuclear level structure of low lying levels of109Cd

Nuclear level structure of low lying levels of¹⁰⁹Cd from¹⁰⁹In decay has been investigated by gamma-gamma angular correlation experiments using a Ge(Li)-NaI(Tl) fast coincidence arrangement. From the measurement on the 347.4?326.3, 347.4–650.1, 287.7–650.1, 203.3–420.5, 203.3–619.3 keV cascades spin-parity assignments of 5/2⁺,1/2⁺,7/2⁺,5/2⁺, 7/2⁺,5/2⁺,9/2⁺, and 9/2⁺, have been made to the ground, 59.5, 203.3, 347.4, 623.8, 673.7, 822.5 and 997.5 keV states, respectively, of¹⁰⁹Cd. The results have been discussed and compared with the previous works.     

Nuclear binding energies and liquid drop parameters in the extended Thomas-Fermi approximation

Using the extended Thomas-Fermi model, we calculate average nuclear binding energies with Skyrme type effective interactions. The total energy is minimized with respect to variations of the nucleon densities without the use of wave functions or adjustable parameters. We obtain binding energies only ～2–7 MeV higher than self consistenly averaged Hartree-Fock energies. By least-square fits we determine the liquid drop parameters of different effective interactions very accurately. Shell effects are added perturbatively and lead to total energies within 5–10 MeV of the exact Hartree-Fock results.     

Triplet of Nuclear Scissors Modes

Physics of Atomic Nuclei - Low energy $$M1$$ excitations are studied within the Time Dependent Hartree–Fock–Bogoliubov (TDHFB) approach. The solution of TDHFB equations by the Wigner...     

Nuclear spin-spin coupling constants prediction based on XGBoost and LightGBM algorithms

Nuclear magnetic resonance (NMR) is a robust method for the analysis of molecular complex structures, and the measurement of the nuclear spin–spin coupling constant is the key. In this paper, based on the 3D coordinates of the atoms in the molecule, the spin–spin coupling constants of atom-pairs are directly predicted using Extreme Gradient Boosting (XGBoost) and Light Gradient Boosting Machine (LightGBM). The calculated result of DFT method is taken as the target value. Experiment shows that LightGBM (R²: 0.93) overall performance is better than XGBoost. In some molecules, the predicted fit (R²) of the coupling constant between atoms even reached 1.00. This research avoids complex quantum mechanics and can assist in NMR to gain insight into the structure and dynamics of molecules, thereby enriching the data information analysis method of nuclear magnetic interaction.     

3-Naphthyl-4-Quinazolone Infrared and Nuclear Magnetic Resonance Band Assignments

Abstract

The ir and nmr spectra of 24 3-naphthyl-4-quinazolones were examined. There are three principal ir bands in the 1500 and 1705 cm^?1 region of the spectra. The first at 1685–1705 cm^?1 is assigned to the tertiary amide carbonyl (ArCONR₂), the second at 1593–1645 cm^?1 to the anil chromophore (ArN=C-N) and the third to the naphthalene ring at 1600 cm^?1. The nmr band assignments are straight forward.     

Nuclear structure of 144Nd in IBM and DPPQ model

The dynamic deformation theory based on the pairing-plus-quadrupole model is employed for a detailed study of the N = 84 vibrational nucleus ¹⁴⁴Nd. The level energies, shape parameters, B(E2) values, ρ(E0), X(E0/E2) and δ(E2/M1) values are compared with available data. The level structure is also analyzed in IBM-1 and their F-spin character in IBM-2 is discussed. The A-dependence of the IBM-2 parameters is compared with those of the DPPQ model and the E2 moments of ^146–150Nd are presented.     

Calculation of Nuclear Stopping in the Semiclassical Approximation

Technical Physics - The results of calculating nuclear stopping in the semiclassical approximation for the H–Be, H–C, H–W, O–C, O–Be, and O–Al systems are...     

Nuclear Corrections in ν A DIS and Their Compatibility with Global NPDF Analyses

We perform a global χ ²-analysis of nuclear parton distribution functions using data from charged current neutrino–nucleus (ν A) deep inelastic scattering (DIS), charged-lepton–nucleus (? ^± A) DIS, and the Drell–Yan (DY) process. We show that the nuclear corrections in ν A DIS are not compatible with the predictions derived from ? ^± A DIS and DY data. We quantify this result using a hypothesis-testing criterion based on the χ ² distribution which we apply to the total χ ² as well as to the χ ² of the individual data sets. We find that it is not possible to accommodate the data from ν A and ? ^± A DIS by an acceptable combined fit. This implies that either the twist-2 parton distribution functions in nuclei are not universal, or that higher-twist terms play a more important role in the nuclear environment and have to be taken into account.     

High-Temperature Dynamic Nuclear Polarization Enhanced Magic-Angle-Spinning NMR

Dynamic nuclear polarization (DNP) transfers electron spin-polarization to nuclear spins in close proximity, increasing sensitivity by two-to-three orders of magnitude. This enables nuclear magnetic resonance (NMR) experiments on samples with low concentrations of analyte. The requirement of using cryogenic temperatures in DNP-enhanced solid-state NMR (ssNMR) experiments may impair the resolution and hence limit its broad application to biological systems. In this work, we introduce a “High-Temperature DNP” approach, which aims at increasing spectral resolution by performing experiments at temperatures of around 180?K instead of?~100?K. By utilizing the extraordinary enhancements obtained on deuterated proteins, still sufficiently large DNP enhancements of 11–18 are obtained for proton and carbon, respectively. We recorded high sensitivity 2D ¹³C–¹³C spectra in?~9?min with higher resolution than at 100?K, which has similar resolution to the one obtained at room temperature for some favorable residues.     

Nuclear stopping power

Inclusive cross sections for protons emitted in 100 GeV proton-nucleus collisions are used to estimate the stopping power of nuclear matter for fast nucleons. The typical recoil momentum obtained for a nucleon struck by the center of a lead nucleus is 4–10 GeV/c, an order of magnitude greater than in p-p collisions, and an order of magnitude smaller than in a naive cascade model. Possible implications for high energy heavy ion collisions are discussed.     

The Nuclear Quadrupole Interaction in High Temperature Superconductors

Abstract

Since their discovery in 1986 [11], the high temperature superconducting (HTS) copper oxides have presented a continuing challenge to both experiment and theory. The identification of the underlying mechanism (or mechanisms) responsible for their superconductivity remains an unanswered question. Numerous theories have been proposed ranging from phonon-mediated pairing of the charge carriers, similar to the Bardeen–Cooper–Schrieffer (BCS) [2] theory developed for conventional low-temperature superconductors, to novel concepts independent of phonons [3–-l0]. For conventional superconductors the variation of the transition temperature T_c , with isotopic mass M (from BCS theory T_c ～ M^?a ) was an important verification of the contribution of electron-phonon interactions to electron pairing. Measurements of this effect of HTS cuprates resulted in isotope shifts much smaller than predicted by theory [ll-14], raising doubts about the role of phonons. However, Barbee [15] argued that the size of the isotope shift is not a unique indicator of phonon-mediated pairing. Since the HTS materials contain Cu ions with partially filled 3d shells, many of the alternative theories of HTS have focused on magnetic interactions and associated spin fluctuations [3–10]. The reader is referred to Ref. 16 for the details of other theories that have been proposed and to the article by Schrieffer and Anderson [17) for an overview discussion of the theory of high temperature superconductivity.     

Nuclear anapole moments

An approximate analytical expression is obtained for the parity violating electromagnetic, so-called anapole, moment of a spherical nucleus. The result iis confirmed by numerical computation in the Woods-Saxon potential for the nuclei ¹³³Cs, ^203,205Tl, ²⁰⁷Pb, ²⁰⁹Bi. The effective coupling constant of the electromagnetic P-odd electron-nucleus interaction constitutes 0.3–0.4 of the Fermi constant.     

Asymptotic Normalization Coefficients (Nuclear Vertex Constants), Three-Body Asymptotic Normalization Functions (On-Shell Vertex Functions) and Nuclear Astrophysics

In the present review work, the main methods of the determination of asymptotic normalization coefficients (or respective nuclear vertex constants) for the A + x → B channel and of threebody asymptotic normalization functions (or respective on-shell vertex functions) for the A + b + c → B channel are briefly discussed. The main attention is paid both to the use of the specific asymptotic normalization coefficients and three-body asymptotic normalization functions as a source of getting the valuable information about the pair (nucleon–nucleon, nucleon–cluster and cluster–cluster) nuclear interactions and to their application for the specific direct nuclear-astrophysical radiative capture and peripheral transfer reactions at low energies.     

Nuclear Reactions in Micro/Nano-Scale Metal Particles

Low-energy nuclear reactions in micro/nano-scale metal particles are described based on the theory of Bose–Einstein condensation nuclear fusion (BECNF). The BECNF theory is based on a single basic assumption capable of explaining the observed LENR phenomena; deuterons in metals undergo Bose–Einstein condensation. The BECNF theory is also a quantitative predictive physical theory. Experimental tests of the basic assumption and theoretical predictions are proposed. Potential application to energy generation by ignition at low temperatures is described. Generalized theory of BECNF is used to carry out theoretical analyses of recently reported experimental results for hydrogen–nickel system.     

Nuclear quadrupole resonance exchange spectroscopy with shaped radiofrequency pulses

Recent work on the nuclear quadrupole resonance (NQR) investigation of molecular dynamics in the solid state has relied on 2D methods. We report our studies of dynamic processes by 1D shaped pulse NQR spectroscopy. Significant advantages include considerably shorter experimental duration, clear definition of the exchange time window, and avoidance of off-resonance effects. The reorientation of the Cl₃C? group in polycrystalline chloral hydrate [Cl₃C–CH(OH)₂] is considered as a test case. This may be modelled as a three-site exchange process. An analysis of the generalised Bloch–McConnell equation is performed to formulate the kinetic matrix. The present approach involves simultaneous excitation of the sites that undergo chemical exchange by employing a suitably modulated shaped RF pulse, followed by a mixing time, and finally a suitable read pulse for signal detection. The experimental signal intensities are plotted against the mixing time to extract the kinetic parameters, i.e. the exchange rate and the spin-lattice relaxation rate. Variable temperature measurements are carried out to determine the activation parameters. Short experiment times are possible in our 1D mode, enabling a large number of runs to be readily performed as a function of mixing time and temperature. The kinetic and activation parameters obtained in the case of chloral hydrate are in good agreement with recent literature values.     

Nuclear Magnetic Ions of Magnesium,Calcium, and Zinc as a Powerful and Universal Means for Killing Cancer Cells

Magnetic isotope effect controls enzymatic DNA synthesis and strongly, by 2–3 times, suppresses catalytic activity of polymerases and increases even more strongly, by 20–50 times, the mortality of cancer cells. Catalyzing ions ²⁵Mg²⁺, ⁴³Ca²⁺, and ⁶⁷Zn²⁺ carrying magnetic nuclei are shown to efficiently kill cancer cells. The advantage of these ions for practical medicine is that being injected in blood they are captured selectively and almost exclusively by cancer cells inducing their death. The healthy cells capture these ions much less efficiently (perhaps due to the lower penetrability of their membranes) and are not vulnerable to these ions in comparison with cancer cells. Of course, penetrability of cells is identical for magnetic and nonmagnetic ions, but only the former kill cancer cells.     

Viscosity Correlations with Nuclear (Proton) Magnetic Resonance Relaxation in Oil Disperse Systems

Using nuclear (proton) magnetic resonance relaxometry (NMRR) was studied oil disperse systems. Dependences of NMR–relaxation parameters—spin–lattice T_1i, spin–spin T_2i relaxation times, proton populations P_1i and P_2i, and petrophysical correlations were received for light and heavy oils. Experimental results are interpreted on the base of structure-dynamical ordering of oil molecules with structure unit formation.     

Nuclear magnetic resonance studies in rare earth ternary phosphides

The results of³¹P Knight shift (KS) and spin-lattice relaxation time (T ₁) measurements in the temperature interval 4.2–300 K are reported for the compounds RENi₂P₂(RE=Ce, Eu, Yb) in order to understand the nature of the ground state in these compounds. KS results conclusively establish that all these compounds exhibit non-magnetic ground states. The temperature dependence of spin-fluctuation temperature (T _sf) in each case is estimated from the measured data. For EuNi₂P₂ the values ofT _sf above 77 K qualitatively agree with those obtained from Mössbauer and susceptibility data employing ionic interconfigurational fluctuation model, but disagree at lower temperatures.     

Nuclear Structure of 12,14Be Within Deformed Quasi-Particle Random Phase Approximation (DQRPA)

We developed a deformed quasi-particle random phase approximation (DQRPA) to describe the Gamow–Teller (GT) transitions on even–even neutron-rich nuclei. To describe deformed nuclei, we exploited the deformed axially symmetric Woods–Saxon potential, the deformed BCS, and the deformed QRPA with realistic two-body interaction calculated by Brueckner G-matrix based on Bonn CD potential. The deformed single particle states are expanded in terms of the spherical harmonic oscillator basis in order to take the realistic G-matrix stored in the spherical basis. We calculated GT strength distributions, B(GT), of two nuclei ^12,14Be for many different deformation parameter β ₂ values as a function of the excitation energy E _ex w.r.t. the ground state of a parent nucleus. Our results for ¹²Be predict to prefer a prolate shape and B(GT) results of ¹⁴Be turn out to be independent of the β ₂ values.