Thepd3Heηreaction near threshold

Photoionization of fine structure levels of Ne III

Low energy Auger electron spectroscopy of titanium nitrides for quantitative analysis

In a conventional borehole logging tool with an isotopic neutron source, the neutron emission energy is typically less than 5 MeV and the slowing down process is dominated by scattering from hydrogen in the rock matrix pores. For a 14 MeV DT source, however, transport from the starting energy to approximately 1 MeV is governed significantly by scattering (elastic and, particularly, inelastic) from nuclei such as C, O, Si, etc., contained in the rock matrix. From 1 MeV to thermal, transport is dominated by hydrogen. Both energy regions are of interest: the high energy region provides information about the rock parameters and the low energy region provides information about the pore volume fraction. Measurement of low energy transport is well established. To measure high energy transport, i.e., the 14/spl rarr/1 MeV slowing down length, detectors capable of measuring 1 MeV flux are required at two different source-to-detector spacings. In this paper, we examine the feasibility of using very high pressure /sup 4/He counters (up to 40 ATM) as detectors of borehole moderated 14 MeV neutrons, and present a very simple technique for neutron/gamma discrimination. These detectors are candidates because of a scattering resonance near 1 MeV and low scattering and absorption cross sections at lower energies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sum rule inequalities and subtractions in π π dispersion relations

It is widely accepted that a new phase structure will emerge in nuclear matter at high temperature and density. In this article the QCD (quantum chromodynamic) phase transitions are briefly reviewed from both theoretical and experimental aspects. Basing on the general principle of QCD and modern phase transition theory, we analyze potential phases in the strong interacting nuclear matter. The phase structure could be understood intuitively through the breaking and restoration of fundamental symmetries of QCD. In the space spanned by the temperature, baryon and isospin chemical potential there are different phases corresponding to three important symmetries, i.e. the color, chiral and isospin. At low temperature and density, the color and isospin symmetries are preserved, while the chiral one is spontaneously broken. At high temperature or density, the color or isospin or both of them would be broken as the chiral restoration. In order to explore the detailed structure of the phase diagram various theoretical approaches of studying the transitions are introduced, such as lattice QCD, mean field calculation basing on effective models, functional renormalization group and Dyson-Schwinger equation. In experiments there are two kinds of physics systems to realize conditions of QCD phase transitions: the relativistic heavy ion collisions and compact stars. Nuclear collision is the only way to approach hot QCD in laboratories on the earth. We focus on some robust probes to the quark gluon plasma formed in the early stage of the collisions. There are generally two types of the traditional signals which are focusing on the profile of the fire ball and the internal interaction of it respectively. For the first case we introduce collective flows as observables for the shape of fire ball. While for the second we review the jet quenching and the heavy flavor suppression. In the hot fire ball the classical transport theory should be modified by including quantum effects induced by the chiral restoration. This novel transport phenomenon of QCD at high temperature is named by the chiral anomalous transport. On the phase transitions at high density, we review the recent progress on color superconductivity and pion superfluidity. Color superconductivity is formed at high baryon chemical potential when quarks pair with each other into diquarks and condense. While pion superfluidity would emerge at high isospin chemical potential with pion condensate. Model studies suggest these states are able to exist in the core of compact star. By modifying the structure of them, such as the mass-radius relation, these states are expected to be identified by astronomical observation at higher precision. Currently dense systems are difficult to produce at main facilities of the world, such as RHIC (relativistic heavy ion collider) and LHC (large hadron collider) because of the designed high energy scale of the accelerators. Therefore it is a critical need for the facilities which could cover the low and medium energy region where the potential critical point and various phase structures would locate. Considering the running and constructing heavy ion facilities, the CSR (cooler-storage-ring) in Lanzhou and the high intensity HIAF (heavy-ion accelerator facility) in Huizhou, the properties of the new QCD phases and their realizations in nuclear collisions will be the new frontier of nuclear physics in China.

Angular and energy dependence of the elastic and the inelastic scattering of protons from nickel isotopes, Ni 58 and Ni 60 , were investigated in the energy range from 7.0 MeV to 15.3 MeV. Angular distributions in the high energy region ( E p ≥10 MeV) showed small difference between both isotopes. Energy dependence of the differential cross sections in the low energy region (7 MeV< E p <9 MeV) showed some fluctuations both for the elastic and the inelastic scattering. The inelastic yield for Ni 58 was larger than that for Ni 60 in the low energy region ( E p ≤9 MeV). These yields decreased gradually as the incident energy increased. The results of present work are compared with our previous one and with the investigations of Thirion et al., Greenlees et al., and Seward.

The ultra-high intensity heavy-ion beam is highly pursued for heavy-ion researches and applications. However, it is limited by heavy-ion production of ion source and space-charge-effect in the low energy region. The Heavy-ion Inertial Fusion (HIF) facilities were proposed in 1970s. The HIF injectors have large cavity number and long total length, e.g., there are 27 injectors in HIDIF and HIBLIC is 30 km in length, and the corresponding HIF facilities are too large and too expensive to be constructed. Recently, ion acceleration technologies have been developing rapidly, especially in the low energy region, where the acceleration of high intensity heavy-ions is realized. Meanwhile, superconducting (SC) acceleration matures and increases the acceleration gradient in medium and high energy regions. The length of HIF injectors can be shortened to a buildable length of 2.5 km. This paper will present a review of a renewed HIF injector, which adopts multi-beam linac-based cavities.

In this work we present a combined fit of the energy spectrum and mass composition data above 6×1017 eV as measured by the Pierre Auger Collaboration and we show that our data can be reproduced by the superposition of two (or more) components, either Galactic or extragalactic. We use a simple astrophysical model with two extragalactic components, one dominant at high energy and the other at low energy, whose superposition generates the so-called “ankle” feature. We find that the component dominating the low (high) energy region is required to be emitted from the sources with a very soft (hard) spectrum. In our best fit scenario the sources contributing above the ankle emit a mixed and increasingly heavier mass composition, whereas a mix of protons and intermediate-mass nuclei is observed below the ankle, which reach the Earth almost una↵ected by the propagation in the intergalactic space. The possible presence of a Galactic population providing the intermediate-mass contribution at low energy is also explored. In order to evaluate our capability to constrain astrophysical models, we finally discuss the impact on the fit results of the main experimental systematic uncertainties and of the assumptions on the quantities a↵ecting propagation, both in the atmosphere and in the intergalactic medium.

Electron stimulated desorption of H − and H + from hydrogen covered tungsten

Accurate measurement of the ionization cross section of the target atom induced by collision between ions and atoms is of great significance for studying the atomic shell process and establishing a suitable theoretical model. The experimental data and the theoretical models mostly concentrate on the cases in the low energy region at present. Only a few experimental data of high energy region are reported due to the limitation of experimental conditions. Which theory is more suitable to describe the ionization cross section of the inner shell of the target atom caused by the high energy heavy ions, is necessarily studied experimentally. The C6+ ions provided by the Heavy Ion Research Facility in Lanzhou Electron Cooling Storage Ring, are used to bombard the Ni target, in which the K-shell X-ray of Ni is measured. The incident energies of C6+ ions are 165, 300, 350 and 430 MeV/u respectively. Through analyzing the intensity ratio of K/K X-ray of Ni, it is found that the influence of incident energy on the intensity ratio of K/K X-ray is not obvious. The intensity ratios of this experiment are greater than the experimental values of incident proton and the calculated values based on the Hartree-Slater theory, which may be caused by the multiple-ionization of the L shell. The production cross sections of Ni K-shell X-ray are calculated by the binary encounter approximation (BEA) model, the plane wave Born approximation (PWBA) model and the energy-loss coulomb-repulsion perturbed-stationary-state relativistic (ECPSSR) theory respectively, which are compared with the experimental results in this paper. It is found that the experimental cross section increases with the increasing incident energy, which is consistent with the trend of BEA model estimation, but the experimental value is obviously lower than the theoretical value. We think that BEA model needs to be modified when describing the ionization process in the high energy region.

The angular distributions of the reactions Al 27 ( p , α)Mg 24 resulting in the ground and first excited states of Mg 24 were measured at 37 energies between 10.5 and 14.5 Mev, making use of proportional counters. Similar behaviour was obtained for both reactions. The variation of the shape of the angular distributions with the bombarding energy is rather smooth in the higher energy region, but becomes rapid with decreasing the bombarding energy. There appear some resonance-like peaks and valleys in the excitation curves at laboratory angles of 50°, 90° and 130° but their positions are not coincident with one another and in the higher energy region these peaks disappear in the excitation curves for the total cross sections. The variations of the excitation curves for the total cross sections and of the shape of the angular distributions with energy in the lower energy region may be due to the fluctuations in the number or properties of the compound nucleus levels and to the interference between the compou...

The electronic band structure of a ferromagnetic chromium spinel CuCr2S4 is calculated self-consistently by using the discrete variational X alpha method. The main features of the band structure are: relatively narrow valence bands constructed mainly from the S 3p orbitals lie in the lower energy region; very narrow bands having mainly d character range over the intermediate energy region and a few d bands with only majority spin cross the Fermi level, which corresponds to the p-type metallic conduction observed; true conduction bands composed of Cu and Cr 4s, 4p orbitals lie in the higher energy region. The valency of each ion obtained from the self-consistent calculation is Cu1.3+(Cr1.55+)2(S1.11-)4 and the atomic spin-polarisation is 3.2, -0.32 and -0.27 for Cr, Cu and S, respectively.

Nuclear physics entails the study of the properties and interactions of hadrons, such as the proton and neutron, and atomic nuclei and it is central to our understanding of our world at the smallest scales. The underlying basis for nuclear physics is provided by the Standard Model of particle physics which describes how matter interacts through the strong, electromagnetic and weak (electroweak) forces. This theory was developed in the 1970s and provides an extremely successful description of our world at the most fundamental level to which it has been probed. The Standard Model has been, and continues to be, subject to stringent tests at particle accelerators around the world, so far passing without blemish. However, at the relatively low energies that are relevant for nuclear physics, calculations involving the strong interaction, governed by the equations of Quantum Chromodynamics (QCD), are enormously challenging, and to date, the only systematic way to perform them is numerically, using a framework known as lattice QCD (LQCD). In this approach, one discretizes space-time and numerically solves the equations of QCD on a space-time lattice; for realistic calculations, this requires highly optimized algorithms and cutting-edge high performance computing (HPC) resources. Progress over the project period is discussed in detail in the following subsections

The energy dependence of dechanneling due to a circular dislocation loop was investigated by a dechanneling model previously proposed by the author. Numerical calculations based on this model show that the dechanneling width, i.e., the dechanneling cross section per length of a dislocation loop, increases with the square root of the ion energy in the low-energy region, and that it has a constant value determined by the maximum displacements of the atomic rows located near the loop in the high-energy region. Analytical considerations also conclude that the energy region where the dechanneling width is proportional to the square root of the ion energy expands proportionally to the square of the radius of the loop, and that the dechanneling width in the high-energy region is proportional to the radius of the loop.

Isospin splitting in the giant resonance of 11B