Overtones of Isoscalar Giant Resonances in medium-heavy and heavy nuclei

A semi-microscopic approach based on both the continum-random-phase-approximation (CRPA) method and a phenomenological treatment of the spreading effect is extended and applied to describe the main properties (particle-hole strength distribution, energy-dependent transition density, partial direct-nucleon-decay branching ratios) of the isoscalar giant dipole, second monopole, and second quadrupole resonances. Abilities of the approach are checked by description of gross properties of the main-tone resonances. Calculation results obtained for the resonances in a few singly- and doubly-closed-shell nuclei are compared with available experimental data.Comment: 12 pages, 14 figures, submitted to Phys. Rev.

Isoscalar Giant Dipole Resonance and Nuclear Matter Incompressibility Coefficient

We present results of microscopic calculations of the strength function, S(E), and alpha-particle excitation cross sections sigma(E) for the isoscalar giant dipole resonance (ISGDR). An accurate and a general method to eliminate the contributions of spurious state mixing is presented and used in the calculations. Our results provide a resolution to the long standing problem that the nuclear matter incompressibility coefficient, K, deduced from sigma(E) data for the ISGDR is significantly smaller than that deduced from data for the isoscalar giant monopole resonance (ISGMR).Comment: 4 pages using revtex 3.0, 3 postscript figures created by Mathematica 4.

Multilayer film shields for the protection of PMT from constant magnetic field

This is the Published Version made available with the permission of the publisher.Photomultiplier tubes (PMTs) are widely used in physical experiments as well as in applied devices. PMTs are sensitive to magnetic field, so creation of effective magnetic shields for their protection is very important. In this paper, the results of measurements of shielding effectiveness of multilayer film magnetic shields on PMT-85 are presented. Shields were formed by alternating layers of a material with high magnetic permeability (Ni-Fe) and high electric conductivity—Cu. The maximum number of bilayers reached 45. It is shown that in weak magnetic fields up to 0.5 mT, the output signal amplitude from PMT-85 does not change for all used multilayer shields. In strong magnetic field of 2–4 mT, the output signal amplitude decrease with 10%–40% depending from the number of layers in the shield. The Pulse distribution of PMT-85 in magnetic field 0.2–4 mT slightly changed in the range 1.1%–1.3% for the case when the number of layers do not exceed 10 and practically did not change for a shield with 45 double layers

Multilayer film shields for the protection of PMT from constant magnetic field

This is the Published Version made available with the permission of the publisher.Photomultiplier tubes (PMTs) are widely used in physical experiments as well as in applied devices. PMTs are sensitive to magnetic field, so creation of effective magnetic shields for their protection is very important. In this paper, the results of measurements of shielding effectiveness of multilayer film magnetic shields on PMT-85 are presented. Shields were formed by alternating layers of a material with high magnetic permeability (Ni-Fe) and high electric conductivity—Cu. The maximum number of bilayers reached 45. It is shown that in weak magnetic fields up to 0.5 mT, the output signal amplitude from PMT-85 does not change for all used multilayer shields. In strong magnetic field of 2–4 mT, the output signal amplitude decrease with 10%–40% depending from the number of layers in the shield. The Pulse distribution of PMT-85 in magnetic field 0.2–4 mT slightly changed in the range 1.1%–1.3% for the case when the number of layers do not exceed 10 and practically did not change for a shield with 45 double layers

Баланс массы ледника Козельский на Камчатке за 1977–2022 гг.

The change in the volume of the Kozelsky Glacier in Kamchatka for the period 1977–2022 (1977–2015 and 2015–2022) was estimated using historical data and modern DEM. During this period, the area of the glacier did not change much. At the same time, its length increased by about 0.7 km, while the width decreased over its almost whole extent. The volume of the glacier decreased by 34.15 ± 6.74 million m3, and its surface became lower by 17.30 m, on the average. The cumulative mass balance amounted 14.70 ± 3.94 m w.e., and the mean annual value –0.33 m w.e. yr–1. In the last 45 years, the ice loss and redistribution to lower hypsometric levels took place on the Kozelsky Glacier. In 1977–2015, the average area change in the altitude of the glacier surface was equal to –17.84 m, the volume decreased by 35.21 ± 7.20 million m3, the cumulative mass balance amounted –15.16 ± 4.17 m w.e., and the mean annual balance –0.40 m w.e. yr–1. In the period 2015–2022, an elevation of the glacier surface was recorded by 0.59 ± 1.55 m on the average, the volume increased by 1.01 ± 2.65 million m3, the cumulative mass balance amounted to 0.50 ± 1.35 m w.e., and the mean annual balance – to 0.07 m w.e. yr–1. During the last decade, a slowdown in the movement of the glacier front down the valley was recorded. In 2012–2022, the glacier front advanced with a velocity of about 5.2 m/year, while it was 17.9 m/year in 1977–2007, and 20.0 m/year in 2007–2012. The current climatic conditions are not favorable for development of glaciers. In 1977–2022, a trend of the summer air temperature rise was observed with a relatively stable amount of precipitation falling during the cold period. The almost continuous (except 1978–1981) advance of the glacier in 1977–2022 can be explained by the influence of the volcanic factor. A thick surface moraine covers more than 2/3 of the glacier area and, thus, prevents the surface ablation. Increased seismic activity associated with active volcanism promotes the ice movement.Дана оценка изменения объёма ледника Козельский на Камчатке за 1977–2022 гг. Площадь ледник за это время практически не изменилась, фронт продвинулся вперёд почти на 0.7 км, объём сократился на 34.15 ± 6.74 млн м3, поверхность в среднем понизилась на 17.3 м, кумулятивный баланс массы составил –14.70 ± 3.94 м в.э., а удельный среднегодовой –0.33 м в.э./год. Продвижение линии фронта в последние 10 лет замедлилось и составляло около 5 м/год

Escape and Spreading Properties of Charge-Exchange Resonances in Bi 208

The properties of charge-exchange excitations of ${}^ {208}$Pb with $\Delta L = 0$, i.e., the isobaric analog and Gamow-Teller resonances, are studied within a self-consistent model making use of an effective force of the Skyrme type. The well-known isobaric analog case is used to assess the reliability of the model. The calculated properties of the Gamow-Teller resonance are compared with recent experimental measurements with the aim of better understanding the microscopic structure of this mode.Comment: 26 pages including references, figure captions and tables. Figures are available upon request at [email protected] (decnet 32858::COLO). Preprint code: IPNO/TH 94-2

Structure of isobaric analog states in 91Nb populated by the 90Zr(a,t) reaction

Decay via proton emission of isobaric analog states (IAS's) in $^{91}{Nb}$ was studied using the $^{90}{Zr}(\alpha,t)$ reaction at $E_\alpha$=180 MeV. This study provides information about the damping mechanism of these states. Decay to the ground state and low-lying phonon states in $^{90}{Zr}$ was observed. The experimental data are compared with theoretical predictions wherein the IAS `single-particle' proton escape widths are calculated in a continuum RPA approach. The branching ratios for decay to the phonon states are explained using a simple model.Comment: 3 figures. submitted to Phys. Lett.

Interfering Doorway States and Giant Resonances. I: Resonance Spectrum and Multipole Strengths

A phenomenological schematic model of multipole giant resonances (GR) is considered which treats the external interaction via common decay channels on the same footing as the coherent part of the internal residual interaction. The damping due to the coupling to the sea of complicated states is neglected. As a result, the formation of GR is governed by the interplay and competition of two kinds of collectivity, the internal and the external one. The mixing of the doorway components of a GR due to the external interaction influences significantly their multipole strengths, widths and positions in energy. In particular, a narrow resonance state with an appreciable multipole strength is formed when the doorway components strongly overlap.Comment: 20 pages, LaTeX, 3 ps-figures, to appear in PRC (July 1997

Template-Assisted Synthesis and Characterization of Passivated Nickel Nanoparticles

Potential applications of nickel nanoparticles demand the synthesis of self-protected nickel nanoparticles by different synthesis techniques. A novel and simple technique for the synthesis of self-protected nickel nanoparticles is realized by the inter-matrix synthesis of nickel nanoparticles by cation exchange reduction in two types of resins. Two different polymer templates namely strongly acidic cation exchange resins and weakly acidic cation exchange resins provided with cation exchange sites which can anchor metal cations by the ion exchange process are used. The nickel ions which are held at the cation exchange sites by ion fixation can be subsequently reduced to metal nanoparticles by using sodium borohydride as the reducing agent. The composites are cycled repeating the loading reduction cycle involved in the synthesis procedure. X-Ray Diffraction, Scanning Electron Microscopy, Transmission Electron microscopy, Energy Dispersive Spectrum, and Inductively Coupled Plasma Analysis are effectively utilized to investigate the different structural characteristics of the nanocomposites. The hysteresis loop parameters namely saturation magnetization and coercivity are measured using Vibrating Sample Magnetometer. The thermomagnetization study is also conducted to evaluate the Curie temperature values of the composites. The effect of cycling on the structural and magnetic characteristics of the two composites are dealt in detail. A comparison between the different characteristics of the two nanocomposites is also provided