Fragmentation cross-section of relativistic oxygen ions and determination of overlap parameter

Fragmentation cross-section of¹⁶O relativistic ions, at two different energies, was measured in CsI crystal. An experiment designed basically to study primary cosmic ray nuclei, was exposed to monoenergetic beam of¹⁶O ions of bevatron. Fragmentation of the ions was observed in a two layer CsI target. Each CsI crystal was 1 inch thick. The main energy of the beam was 2.1 GeV/nucleon. A subsidiary beam of 0.5 GeV/nucleon oxygen-ions was created for this experiment alone. The number of fragmentations occurring in each crystal was used to obtain the total fragmentation cross-section at these energies. The Bradt-Peters overlap parameter was derived from these cross-sections. The experiment was designed and fabricated at the Department of Physics and Astronomy, Louisiana State University, Baton Rouge, USA and was performed in the accelerator facilities of the University of California, Berkeley, Calif., USA.     

An Efficient Approach for the Calculation of Nuclear Overlap Integrals by Means of Binomial Coefficients and Its Application

This paper examines the computational efficiency of the method of evaluating nuclear overlap integrals commonly encountered in nuclear reactions. As will be seen, the present formulation yields compact closed-form expressions which will make the calculation of nuclear overlap integrals easy. For practical applications, the computational technique used must be amenable to rapid evaluation and yield an acceptable degree of accuracy. Finally, the ratios for the non-Borromean two-nucleon halo systems are calculated by using new formulas which are important for the reaction analyses. The results of this calculation have been compared with those obtained according to one of the theoretical articles (Timofeyuk et al., Phys. Rev. C 68:021601(R), 2003). The same numerical results are presented for significant examples and they are briefly discussed.     

A study of erbium,thulium and other rare earth ethyl sulphates

The available sets of crystal field parameters for erbium and thulium ethyl sulphates are used to calculate the Stark levels,g-values, Schottky specific heat, magnetic anisotropy, hyperfine interaction parameters and low temperature specific heat of these compounds. A comparison of these calculations with experimental data shows that one of these sets can be taken to be optimum within the accuracy of various measurements. These parameters along with the already optimised ones for other ethyl sulphates are discussed in the frameworks of electrostatic, angular overlap and superposition models for the crystalline fields. The antibonding energy parameter and ionicity are found to be different for light and heavy compounds and almost constant in either half of the series.     

Analysis of the chemical bond

Starting from the MO-LCAO energy expression with an approximate correction for left-right correlation formalisms are derived that agree with those of some current semi-empirical schemes, but where the parameters usually fitted to experimental results are given explicitly in an ab initio way. The approximations necessary for deriving the different schemes as well as the range of their validity are discussed. For -electron systems ab initio values of the -parameters (both thermochemical and spectral) are derived.     

晶体双折射测量的干涉条纹重迭法

本文介绍用干涉条纹的重迭与否测量晶体双折射。作者用干涉条纹取代光栅的Ｔａｌｂｏｔ像，主要优点是条纹的对比度好。     

Frustration without competing interactions

The concept of frustration is investigated following an idea of Anderson. A simple, frustrated in Anderson's sense, nonrandom classical lattice spin system without competing interactions is discussed, which exhibits infinitely many equilibrium states at low temperature. The overlap distribution function is calculated exactly to be a delta function at zero.     

Lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets

This paper investigates the Lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets D=(r_1D)∪(r_2D (1 r_1-r_2-r_3)/2)∪(r_3D 1 r_3) and E=(r_1E)∪(r_2E 1-r_2- r_3)∪(r_3E 1-r_3),and proves that D and E are Lipschitz equivalent if and only if there are positive integers m and n such that r_1~m=r_3~n.     

Theoretical Investigation on Electronic Transition of Tris(8-quinolinolate) Aluminum Grafted on Poly(p-phenylenevinylene) Units with the Localized-density-matrix Method

An unsystematic molecule PPV‐Alq₃ [3‐(4‐((E)‐2‐(8‐hydroxy‐3‐(4‐styrylstyryl)quinolin‐Alq₂‐6‐yl)vinyl)‐ styryl)‐6‐(4‐styrylstyryl)quinolin‐8‐olate‐Alq₂; q=8‐quinolinolate], which combines poly(p‐phenylenevinylene) with tris(8‐quinolinolate)aluminum, has been studied using a localized‐density‐matrix method. The absorption spectra and electronic transition properties were analyzed and compared with both intermediate neglect of the differential overlap method and the localized‐density‐matrix method. Great efforts have been made on investigating conjugated system on the absorption properties as these can be particularly important for many applications. Two different absorptions of the special molecule, tris(8‐quinolinolate)aluminum grafted on poly(p‐phenylenevinylene) units, were further discussed with density matrices. For the molecule, the first absorption peak is at 413 nm near the purple light. Two 8‐hydroxyquinolines have very slight electronic transition properties. Another absorption peak is at 237 nm. The second characteristic peak of molecule is completely different from that of the first one, which comes from contribution of 8‐hyroxyquinolines in the two different side chains. Our studies show that electronic transition properties of poly(p‐phenylenevinylene) can be effectively tuned by grafting tris(8‐quinolinolate)‐aluminum on poly(p‐phenylenevinylene) from the standpoint of transition energies, frontier molecular orbitals and density matrices.