Range and Range Straggling of 97 keV 224Ra Particles in Gases

1971 ◽  
Vol 49 (8) ◽  
pp. 1004-1017 ◽  
Author(s):  
J. Leon ◽  
N. H. Steiger-Shafrir
Keyword(s):  
High Precision ◽  
Energy Region ◽  
Detailed Comparison ◽  
Nuclear Stopping ◽  
Range Distribution ◽  
Medium Mass ◽  
Gaseous Media ◽  
Range Determination ◽  
Good Agreement

High precision range and straggling measurements of 96.5 keV224Ra α-disintegration recoil particles in various gaseous media are described. Special emphasis is placed on the development of a uniform and non-degrading recoil source in order to insure accurate range determination and to prevent broadening of the straggling results by the source. Excellent symmetry for the range distribution curves for all, even the heavy gases, was obtained. The performance of the measurements in gases, where successive collisions can be considered as uncorrelated, enabled a detailed comparison with theoretical treatments of the nuclear stopping mechanism, dominating in this energy region. The results obtained were compared with the Lindhard theory and show good agreement, especially for the medium mass gases.

Pion–pion scattering in a model satisfying crossing symmetry, analyticity, and approximate unitarity

1976 ◽  
Vol 54 (10) ◽  
pp. 1022-1033
Author(s):  
D. H. Boal ◽  
J. W. Moffat
Keyword(s):  
Phase Shift ◽  
Energy Region ◽  
Detailed Comparison ◽  
Phase Shifts ◽  
Low Energy ◽  
Pion Scattering ◽  
Crossing Symmetry ◽  
Mandelstam Analyticity ◽  
Good Agreement

Phase shifts for π–π scattering are obtained from a model satisfying Mandelstam analyticity, exact crossing symmetry, and approximate unitarity in the range 2mπ ≤ s1/2 ≤ 1.3 GeV. The low energy region is dominated by the ρ, ε, and S* poles; the δ00 phase shift is in good agreement with the data obtained by Protopopescu et al. A detailed comparison is made with the available world's data on π–π scattering.

scholarly journals Separate Universe calibration of the dependence of halo bias on cosmic web anisotropy

2020 ◽  
Vol 499 (3) ◽  
pp. 4418-4431 ◽  
Author(s):  
Sujatha Ramakrishnan ◽  
Aseem Paranjape
Keyword(s):  
Dark Matter ◽  
High Precision ◽  
Gaussian Distribution ◽  
Initial Perturbation ◽  
Analytical Framework ◽  
Web Environment ◽  
Wide Range ◽  
Galaxy Assembly ◽  
Very High ◽  
Good Agreement

ABSTRACT We use the Separate Universe technique to calibrate the dependence of linear and quadratic halo bias b1 and b2 on the local cosmic web environment of dark matter haloes. We do this by measuring the response of halo abundances at fixed mass and cosmic web tidal anisotropy α to an infinite wavelength initial perturbation. We augment our measurements with an analytical framework developed in earlier work that exploits the near-lognormal shape of the distribution of α and results in very high precision calibrations. We present convenient fitting functions for the dependence of b1 and b2 on α over a wide range of halo mass for redshifts 0 ≤ z ≤ 1. Our calibration of b2(α) is the first demonstration to date of the dependence of non-linear bias on the local web environment. Motivated by previous results that showed that α is the primary indicator of halo assembly bias for a number of halo properties beyond halo mass, we then extend our analytical framework to accommodate the dependence of b1 and b2 on any such secondary property that has, or can be monotonically transformed to have, a Gaussian distribution. We demonstrate this technique for the specific case of halo concentration, finding good agreement with previous results. Our calibrations will be useful for a variety of halo model analyses focusing on galaxy assembly bias, as well as analytical forecasts of the potential for using α as a segregating variable in multitracer analyses.

scholarly journals In-Depth Verification of a Numerical Model for an Axisymmetric RC Dome

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2152
Author(s):  
Przemysław Czumaj ◽  
Sławomir Dudziak ◽  
Zbigniew Kacprzyk
Keyword(s):  
Three Dimensional ◽  
Spatial Models ◽  
Detailed Comparison ◽  
The Finite Element Method ◽  
Robot System ◽  
Engineering Structures ◽  
Computational Analyses ◽  
Computational Systems ◽  
Good Agreement ◽  
Made In

The designers of civil engineering structures often have to face the problem of the reliability of complex computational analyses performed most often with the Finite Element Method (FEM). Any assessment of reliability of such analyses is difficult and can only be approximate. The present paper puts forward a new method of verification and validation of the structural analyses upon an illustrative example of a dome strengthened by circumferential ribs along the upper and lower edges. Four computational systems were used, namely Abaqus, Autodesk Robot, Dlubal RFEM, and FEAS. Different models were also analyzed—two-dimensional (2D) and three-dimensional (3D) ones using continuum, bar, and shell finite elements. The results of the static (with two kinds of load—self-weight and load distributed along the upper ring) and modal analyses are presented. A detailed comparison between the systems’ and models’ predictions was made. In general, the spatial models predicted a less stiff behavior of the analyzed dome than the planar models. The good agreement between different models and systems was obtained for the first natural frequency with axisymmetric eigenmodes (except from the Autodesk Robot system). The presented approach to the verification of complex shell–bar models can be effectively applied by structural designers.

Nuclear stopping and collective flow in CSR/LanZhou energy region

2011 ◽  
Vol 85 (6) ◽  
pp. 947-952 ◽  
Author(s):  
X. -F. Luo ◽  
X. Dong ◽  
M. Shao ◽  
C. Li ◽  
H. -F. Chen ◽  
...  
Keyword(s):  
Energy Region ◽  
Collective Flow ◽  
Nuclear Stopping

scholarly journals Mobility of an axisymmetric particle near an elastic interface

2016 ◽  
Vol 811 ◽  
pp. 210-233 ◽  
Author(s):  
Abdallah Daddi-Moussa-Ider ◽  
Maciej Lisicki ◽  
Stephan Gekle
Keyword(s):  
Detailed Comparison ◽  
Boundary Integral ◽  
Particle Orientation ◽  
Spheroidal Particle ◽  
Analytical Approximations ◽  
Elastic Interface ◽  
General Relations ◽  
Independent Parameters ◽  
Membrane Particle ◽  
Good Agreement

Using a fully analytical theory, we compute the leading-order corrections to the translational, rotational and translation–rotation coupling mobilities of an arbitrary axisymmetric particle immersed in a Newtonian fluid moving near an elastic cell membrane that exhibits resistance towards stretching and bending. The frequency-dependent mobility corrections are expressed as general relations involving separately the particle’s shape-dependent bulk mobility and the shape-independent parameters such as the membrane–particle distance, the particle orientation and the characteristic frequencies associated with shearing and bending of the membrane. This makes the equations applicable to an arbitrary-shaped axisymmetric particle provided that its bulk mobilities are known, either analytically or numerically. For a spheroidal particle, these general relations reduce to simple expressions in terms of the particle’s eccentricity. We find that the corrections to the translation–rotation coupling mobility are primarily determined by bending, whereas shearing manifests itself in a more pronounced way in the rotational mobility. We demonstrate the validity of the analytical approximations by a detailed comparison with boundary integral simulations of a truly extended spheroidal particle. They are found to be in a good agreement over the whole range of applied frequencies.

scholarly journals The evidence for a spatially flat Universe

2020 ◽  
Vol 496 (1) ◽  
pp. L91-L95 ◽  
Author(s):  
George Efstathiou ◽  
Steven Gratton
Keyword(s):  
High Precision ◽  
Strong Support ◽  
Inflationary Cosmology ◽  
Density Parameter ◽  
Acoustic Oscillations ◽  
Astrophysical Data ◽  
Flat Universe ◽  
Polarization Spectra ◽  
The Universe ◽  
Good Agreement

ABSTRACT We use a new and statistically powerful Planck likelihood to show that the Planck temperature and polarization spectra are consistent with a spatially flat Universe, in contrast to recent claims in the literature. When combined with other astrophysical data, particularly geometrical measurements of baryon acoustic oscillations, our likelihood constrains the Universe to be spatially flat to extremely high precision. We deduce a curvature density parameter ΩK = 0.0004 ± 0.0018 in good agreement with the 2018 results of the Planck team. In the context of inflationary cosmology, the observations offer strong support for models of inflation with a large number of e-foldings and disfavour models of incomplete inflation.

Temperature and composition measurements from the l.r.i.r. and l.i.m.s. experiments on Nimbus 6 and 7

1980 ◽  
Vol 296 (1418) ◽  
pp. 205-218 ◽  
Keyword(s):  
High Precision ◽  
Trace Gas ◽  
Transport Problems ◽  
Rocket Measurements ◽  
Inversion Techniques ◽  
And Inversion ◽  
First Time ◽  
Good Agreement ◽  
Composition Measurements

The limb radiance inversion radiometer (l.r.i.r.) on Nimbus 6 was the first orbiting infrared limb scanner. It had four channels with which to determine temperature, Oz and H aO in the stratosphere and low mesosphere. The limb infrared monitor of the stratosphere (l.i.m.s.) is a similar six-channel instrument launched on Nimbus 7 in October 1978 to measure temperature, O 3 , H 2 O , NO 2 and HNO 3 . The instrumentation and inversion techniques are briefly described. In this method, the outwelling radiance in the 15 pm bands of CO 2 is inverted to yield temperatures as a function of pressure; the temperature is then used w ith the radiance emitted by a trace gas to determine its concentration. L.r.i.r. temperature and ozone results show high precision and good agreement with rocket measurements from the tropopause into the mesosphere. Preliminary l.i.m.s. results show that temperatures may be retrieved into the troposphere, and the capability to determine constituent concentrations in the part / 10 9 range from a satellite for the first time. The application of such data for photochemical dynamical and transport problems is discussed.

Design optimization of high-precision aerostatic equipment based on orifice restriction

2019 ◽  
Vol 233 (10) ◽  
pp. 3459-3474
Author(s):  
Tao Lai ◽  
Xiaoqiang Peng ◽  
Junfeng Liu ◽  
Chaoliang Guan ◽  
Xiaogang Chen ◽  
...  
Keyword(s):  
Finite Difference Method ◽  
High Precision ◽  
Structural Parameter ◽  
Error Feedback ◽  
Aerostatic Bearing ◽  
Proposed Model ◽  
Gas Gap ◽  
Processing Difficulty ◽  
Optimum Working ◽  
Good Agreement

The aerostatic lubrication model with orifice restriction is built based on finite difference method. The model is solved by combination of flux-error feedback and optimization of grids parameter. The stiffness of aerostatic bearing can be improved by reducing the diameter of the orifice, but the optimum working gas gap is reduced and the processing difficulty of surface throttle is improved. The experiments of load and stiffness are carried out on the slider (50 × 50 mm) with the diameter of orifice at 50 µm. The experimental results and theoretical calculation are in good agreement; thus, the model is verified. The structural parameter of two, three, and four orifice gas-bearings is optimized, respectively, based on the proposed model, and the optimum positions of the orifices are obtained. According to the results, the aerostatic bearing guideways, made up of optical material (K9), are manufactured by some optical ways, and the lubrication of the small gas gap is guaranteed; meanwhile, the straightness accuracy of the aerostatic bearing guideways is 0.1 µm/200 mm. The analysis result verifies that the calculation method and the aerostatic lubrication model are significant to the design of high-precision aerostatic equipment.

Longitudinal characterization of the wake and electron bunch in a laser wakefield accelerator

2019 ◽  
Vol 85 (1) ◽  
Author(s):  
Zhijun Zhang ◽  
Wentao Wang ◽  
Jiansheng Liu ◽  
Ming Fang ◽  
Wentao Li ◽  
...  
Keyword(s):  
Electron Bunch ◽  
Detailed Comparison ◽  
Beam Loading ◽  
Space Rotation ◽  
Laser Wakefield ◽  
Chirp Compensation ◽  
Wakefield Accelerator ◽  
Good Agreement ◽  
Laser Wakefield Accelerator

Energy chirp compensation of the electron bunch (e-bunch) in a laser wakefield accelerator, which is caused by the phase space rotation in the gradient wakefield, has been applied in many schemes for low energy spread e-bunch generation. We report the experimental observation of energy chirp compensation of the e-bunch in a nonlinear laser wakefield accelerator with a negligible beam loading effect. By adjusting the acceleration length using a wedge-roof block, the chirp compensation of the accelerated e-bunch was observed via an electron spectrometer. Apart from this, some significant parameters for the compensation process, such as the longitudinal dispersion and wakefield slope at the bunch position, were also estimated. A detailed comparison between experiment and simulation shows good agreement of the wakefield and bunch parameters. These results give a clear demonstration of the longitudinal characteristics of the wakefield in a plasma and the bunch dynamics, which are important for better control of a compact laser wakefield accelerator.

scholarly journals Data Analysis and Calibration of Radiocarbon Dating Results from the Cemetery of the Marquises of Jin

Radiocarbon ◽  
2001 ◽  
Vol 43 (1) ◽  
pp. 55-62 ◽  
Author(s):  
Xiangyang Lu ◽  
Zhiyu Guo ◽  
Hongji Ma ◽  
Sixun Yuan ◽  
Xiaohong Wu
Keyword(s):  
Data Analysis ◽  
High Precision ◽  
Radiocarbon Dating ◽  
Careful Analysis ◽  
Historical Record ◽  
Calibration Result ◽  
Special Part ◽  
Peking University ◽  
Very High ◽  
Good Agreement

The chronology study of the cemetery of Marquises of Jin is valuable to improving the chronological table of Marquis of Jin family. It is also helpful for improving the chronological table of the Zhou Dynasty. The samples were measured at Peking University (PKUAMS). We also made an interlaboratory check with Isotrace to ensure the accuracy. By careful analysis of archaeological information, we built different models and calibrated by OxCal. The calibration results, both sampling contexts and estimations, are in very good agreement with the historical record. Because the dates of some events correspond to the special part of the curve, the calibration gets very high precision. The calibration result of tomb M93 suggests that its host is Marquis Shangshu instead of Marquis Wen.

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