Site Selectivity in γ-Ray Holography

The possibility of imaging the local environments of nuclei with different hyperfine interaction parameters using complex γ-ray holography is investigated. The discussion is based on calculations performed for magnetite Fe₃ O₄, in which Fe ions occupy two nonequivalent positions in the unit cell characterized by different sets of hyperfine interaction parameters. This revised version was published online in September 2006 with corrections to the Cover Date.     

Neutron Activation Analysis of Lipsticks Using γ-Ray Spectrometry

Neutron activation analysis with -ray spectrometry was used to measure the concentrations of various elements in lipsticks of popular Indian and foreign brands. The aim of the present work was to study the possibility of existence of trace elements in samples of lipsticks (the ingredients of which are mostly organic in nature) and to see whether trace elements could distinguish lipsticks of different Indian and foreign brands from the forensic point of view apart from their inter-se differentiation. In the different samples of lipsticks that were analysed the following elements were detected: Au, Ba, Br, Ca, Cs, Fe, Na, Ru, Sb, Sc, Ta, Yt, Zn, Rb, and Se. It was found that inter-se differentiation of lipsticks was possible on the basis of concentrations of trace elements and their profile. Concentration of bromine in samples of lipsticks identified lipsticks of different Indian brands. Samples of lipsticks of Indian and foreign brands could be differentiated on the basis of concentrations of cesium, antimony and scandium which were found to be higher in foreign brands as compared to those in Indian brands.     

Radiation Hardness of Nd:GdVO4 Laser Crystal under γ-Ray Irradiation

Physics of Wave Phenomena - The radiation hardness of neodymium-doped gadolinium vanadate crystal (Nd:GdVO4) has been investigated. Crystal with sizes of 4×4×8 mm doped to a level of 0.5%...     

Nonisothermal Crystallization Behavior of Polypropylene Grafted Silane and Styrene Using γ-Ray Irradiation

Polypropylene grafted silane and styrene (named PP-g-Si/St in this article) was successfully prepared by radical graft polymerization initiated by γ-ray irradiation. The influence of total absorbed dose on the graft ratio of vinyltrimethoxysilane onto PP and the melt flow rate (MFR) of the PP-g-Si/St product were studied. The effect of graft ratios of vinyltrimethoxysilane on the melting point and nonisothermal crystallization kinetics of PP-g-Si/St was investigated by the method of differential scanning calorimetry (DSC). With increasing vinyltrimethoxysilane and styrene (used as viscosity modifier and free radical source) grafted on PP, the melting point of PP-g-Si/St became lower. Several different analysis methods, including those of Avrami, Jeziorny, and Mo and colleagues, were employed to describe the nonisothermal crystallization process of the grafted samples. The results indicate that the peak temperature of crystallization of PP-g-Si/St sample was lower than that of virgin PP. Crystallization kinetics revealed that the rates of nucleation and growth were affected differently by the graft ratio of vinyltrimethoxysilane onto PP. The activation energy was calculated on the basis of the method of Kissinger, and the values were 253.6 and 215.7 kJ/mol for virgin PP and PP-g-Si/St, respectively.     

Determining theCP-violating phase γ

The weak phase γ is conventionally probed by theB _s→ρ ⁰ mode. The predicted rate is tiny. Even if aB _s→ρ ⁰ K _s rate difference could be established, it would not be clear that sin 2γ had been measured, because amplitudes with other weak phases may contribute significantly. Non-CP eigenstates, such asB _s →D _s ^± K ^?, have a two-fold advantage overB _s→ρ ⁰ K _s. Their rates are orders of magnitude above that forB _s→ρ ⁰ K _s, and they probe theCP-violating phase γ, without any contamination from other weak phases. Detailed time-dependent studies of non-CP eigenstates remove possible final-state phases and extract the weak phase γ.     

A soluble γ-unstable hamiltonian

A simple five-dimensional hamiltonian for the nuclear shape is solved analytically for any value of a parameter whose variation describes vibration about a spherical equilibrium at one extreme and a rigid non-spherical but γ-unstable nucleus at the other. Spectra and E2 transition rates are compared with results from the interacting boson model.     

Exclusive γ(*)γ processes

A short review of experimental and theoretical results on the large angle cross sections"γγ→two mesons"and the form factors γ*γ→P = {π,η,η′} is given.     

Form factor π0 → γ* + γ* at different photon virtualities

The π⁰ γγ vertex for virtual photons of squared masses q ₁ ² and q ₂ ² plays a vital rôle in several physical processes; for example for q ₁ ² < 0, q ₂ ² < 0, in the two-photon physics reaction e ⁺ e ^? → e ⁺ e ^?π⁰, and for q ₁ ² > 0, q ₂ ² > 0, in the annihilation process e ⁺ e ^? → π⁰ l ⁺l^?. It is also of interest because of its link to the axial anomaly. We suggest a new approach to this problem. We have obtained a closed analytic expression for the vertex in the limit in which at least one of ¦q ₁ ² ¦ and ¦q ₂ ² ¦ is large for arbitrary fixed values of the ratio q ₁ ² /q ₂ ² . We compare our results with those obtained previously by Brodsky and Lepage. It should be straightforward to test our predictions experimentally.     

Applications of Spectroscopy in the Study of Glassy Solids Part I. Introduction, γ-Ray Spectroscopy (Mössbauer Effect), X-Ray Absorption Fine Structure,UV Absorption,and Visible Spectra

Abstract

Interest in glasses and the amorphous solid state in general, having for a long time been limited t o the separate camps of silicate glass technology and polymer science, has in the last few years become very general. This growth and diversification in scientific interest originates jointly in the discovery and utilization of glasses of quite new types e.g., the chalcogenide glasses, and the recognition by chemists and physicists alike that the glassy state is of very general occurrence in nature, with examples now being known from every class of chemical substance, whether metallic, vander Waals, covalent, or ionic in the interparticle bond character.     

In-beam γ-ray spectroscopy with GASP

The performance of the multi-detector array GASP is described in detail with emphasis on the improvement due to utilization of ancillary detectors. GASP has been running for three years producing interesting new data on different nuclear structure topics. The study of the decay-out of superdeformed bands in the A=130 mass region is presented. The sudden disappearance of the superdeformed bands in the odd^{133, 135, 137}Nd isotopes is explained by the Total Routhian Surface calculations through a change of the nuclear shape which is microscopically related to the transfer of the valence neutron from a N=6 to a N=4 Nilsson orbital. A transient fieldg-factor measurement in the superdeformed band of¹³³Nd will also be presented. A meang-factor of $\bar g = 0.31(8)$ has been determined at the I*=41/2⁺ superdeformed state. The experimental value is compared with theoretical predictions and supports the assignment of the superdeformed band to thev[660]1/2⁺ Nilsson intruder orbital.     

Probing the photon at γe-colliders

We investigate the feasibility of studying the photon structure function at a e-collider. We show that the deep inelastic probe of the real photon by a highly virtual photon in such a collider will extend significantly thex andQ ² range presently accessible ate ⁺ e ^– colliders. In addition, we study the production of large transverse momentum dijet final states to determine the sensitivity of these cross sections to different parametrisations of the quark and gluon distributions in the photon.     

Model with strong γ4 T-violation

We extend the T violating model of the paper on ``Hidden symmetry of the CKM and neutrino-mapping matrices" by assuming its T-violating phases χ_↑ and χ_↓ to be large and the same, with χ=χ_↑=χ_↓. In this case, the model has 9     

In-beam γ-ray spectroscopy of 103Cd

Excited states of ¹⁰³Cd were studied in the reaction ⁵⁸Ni(⁵⁰Cr,4pn)¹⁰³Cd. The NORDBALL array with neutron and charged particle detectors was employed for the detection of γ rays and light evaporated particles. The level scheme of ¹⁰³Cd was significantly extended. A strong cascade of E2 transitions connecting negative parity states was found. Shell model calculations were performed and positive parity excited states were interpreted in terms of neutron-particle and proton-hole excitations with respect to the doubly magic N = Z = 50 core. The negative parity band was well reproduced by the total routhian surface calculations.     

观测来自银道面的TeV γ射线

给出来自银经79.3866°的银道面的TeV γ射线的观测结果.数据是在1995年10月至1998年11月间的晴朗无月夜,用兴隆站的大气契伦科夫望远镜ACT2和ACT3以向源–背景(ON–OFF)观测方式取得的,总观测时间为224.4h.在望远镜计数服从高斯分布的情况下,导出了最大似然比λ的表达式,它直接给出显著性水平的概率.用它分析观测资料,在统计误差范围内没发现有来自银道面的TeV γ射线.     

Isothermal decomposition of γ-irradiated palladium acetate

The isothermal decomposition of un-irradiated (pristine) and pre-γ-irradiated palladium acetate was studied in the temperature range (498–508 K) and in air using the isothermal thermogravimetric technique. The data were analysed using various solid state reaction models. The results showed that the kinetics of isothermal decomposition of palladium acetate was governed by random nucleation reaction (Erofe'ev equation A ₃). The activation energies of the main decomposition process for un-irradiated and pre-γ-irradiated samples were calculated. The change in texture and crystal structure of the investigated palladium acetate by γ-irradiation was studied using electron microscopy and X-ray diffraction techniques.     

Jumplike deformation of γ-irradiated polymethyl methacrylate

Nonuniformity of the microdeformation rate and the parameters of microdeformation jumps were studied in the creep regime for a polymethyl methacrylate irradiated by various dozes of the Co-60 γ radiation. The creep rate during compression of the polymethyl methacrylate was measured by an interferogram on 300-nm deformation increments. It is shown that the periods L of rate oscillations (jumps of deformation) on three scale levels are dependent on the irradiation doze and are also changed after prolonged exposure of samples in air. In the doze range 0 to 330 kGy, both a decrease and an increase in L are observed, which corresponds to the unstable kinetics of radiation chemical processes. The deformation jumps permit estimates of the radiation effect on various structural levels. It is concluded that the effect of radiation on coarser microstructural formations is the largest.

     

EPR study of γ-irradiated three-furancarboxylic acid

The electron paramagnetic resonance of γ-irradiated single crystals of three-furancarboxylic acid has been studied for different orientations of the crystals in a magnetic field. The radicals produced by γ-irradiation have been investigated between 123 and 350 K. The spectra were found to be temperature dependent, and radiation damage centers were attributed to the radical. The principal values of the g-tensor were determined. The results were found to be in good agreement with the existing literature data and theoretical predictions.