The transformation of the nitrogen isotope of mass 15 into carbon and helium by bombardment with protons

1949 ◽  
Vol 199 (1059) ◽  
pp. 458-468 ◽  
Keyword(s):  
Angular Distribution ◽  
Nuclear Reaction ◽  
Cross Section ◽  
Nitrogen Isotope ◽  
Photographic Method ◽  
The Sun ◽  
Broad Maximum ◽  
Dispersion Formula ◽  
The One ◽  
Α Particles

Measurements of the ‘cross-section’ of the nuclear reaction N 15 (p, α) C 12 have been made for protons with different values of the energy in the interval between 200 and 450 keV. There are indications of a broad maximum, in the curve showing the variation of ‘cross-section’ with energy, in the neighbourhood of 400 keV, with a width of 150 keV. The partial proton width of the maximum is 250 eV. Extrapolation of the one-level dispersion formula, together with the theory of thermonuclear reactions, gives a lifetime of 3 x 10 4 years for N 15 in the sun. A photographic method of determining the angular distribution of the emitted α-particles is described. The angular distribution near 400 keV is found to be approximately isotropic, the deviations from isotropy being, at most, 10%.

Angular Distribution of α-Particles from the Li7 (p,α) He4 Reaction

1949 ◽  
Vol 2 (1) ◽  
pp. 25 ◽  
Author(s):  
LH Martin ◽  
JC Bower ◽  
DNF Dunbar ◽  
F Hirst
Keyword(s):  
Angular Distribution ◽  
Nuclear Reaction ◽  
Proton Energy ◽  
Electrostatic Generator ◽  
The Asymmetry ◽  
Ancillary Equipment ◽  
Α Particles

A description is given of a 1 MV, electrostatic generator and ancillary equipment which has been used to study the asymmetry in the angular distribution of α-particles from the Li7 (p, α) He4 reaction. The angular distribution of the a-particles is given by the expression Y(θ) =Y(90�)[1 +A(E) cos2θ + B(E)cos4 θ] where A(E) and B(E) are functions of the proton energy. The form of the expression implies the existence of both p and f protons in the nuclear reaction.

Investigation of the 16O+194Pt reaction: One- and two-dimensional dynamical interpretation

2017 ◽  
Vol 26 (04) ◽  
pp. 1750013 ◽  
Author(s):  
D. Naderi ◽  
A. Farmani
Keyword(s):  
Angular Distribution ◽  
Transition State ◽  
Cross Section ◽  
Fission Cross Section ◽  
Degree Of Freedom ◽  
Two Dimensional ◽  
Orientation Degree ◽  
Fission Fragments ◽  
Fission Probability ◽  
The One

In this paper, we applied the Langevin dynamical model to investigate the different aspects of the [Formula: see text]O+[Formula: see text]Pt reaction. Elongation and orientation degree of freedom ([Formula: see text] coordinate) which are the first and second dimensions of dynamical calculations, are presented here. Fission time, fission cross-section, pre-scission neutron multiplicity, and fission probability were calculated using one- and two-dimensional Langevin equations. Also, anisotropy of fission-fragments angular distribution has been investigated based on the transition state model, one- and two-dimensional Langevin dynamical models. It was found that by adding the orientation degree of freedom to calculations, the fission time and pre-scission neutrons multiplicity increases whereas fission cross-section, and fission probability decreases. The two-dimensional dynamical calculations are a better match to the experimental data than the one-dimensional dynamical calculations, when using nominal values for the reduced dissipation coefficient and shape-dependent level density parameter. However, if model parameters are adjusted to reproduce the fission cross-section data, then both the one- and two-dimensional models give a satisfactory match to the fission fragment anisotropy data. Nonequilibrium [Formula: see text] distributions in the dynamical model can better explain the experimental anisotropy of the angular distribution of fission-fragments with respect to the equilibrium [Formula: see text] distribution in saddle and scission point transition state models.

Dombey and Son

2008 ◽  
Author(s):  
Charles Dickens ◽  
Dennis Walder
Keyword(s):  
Family Relationships ◽  
The Sun ◽  
The Novel ◽  
The Earth ◽  
The Future ◽  
Original Illustrations ◽  
The One

Dombey and Son ... Those three words conveyed the one idea of Mr. Dombey's life. The earth was made for Dombey and Son to trade in, and the sun and moon were made to give them light.' The hopes of Mr Dombey for the future of his shipping firm are centred on his delicate son Paul, and Florence, his devoted daughter, is unloved and neglected. When the firm faces ruin, and Dombey's second marriage ends in disaster, only Florence has the strength and humanity to save her father from desolate solitude. This new edition contains Dickens's prefaces, his working plans, and all the original illustrations by ‘Phiz’. The text is that of the definitive Clarendon edition. It has been supplemented by a wide-ranging Introduction, highlighting Dickens's engagement with his times, and the touching exploration of family relationships which give the novel added depth and relevance.

The Tychonic Method for Calculating the Ratio between the Eccentricities of Mars

2021 ◽  
Vol 52 (2) ◽  
pp. 212-234
Author(s):  
Christián C. Carman
Keyword(s):  
The Sun ◽  
Circular Orbits ◽  
The One

In Chapter 16 of Astronomia nova, Kepler describes and applies a method for finding the parameters of what he will call the vicarious hypothesis: a model that still assumes circular orbits and an equant point, but does not assume the bisection of the eccentricity, that is, that the center of the orbit is halfway between the equant point and the Sun. The method allows Kepler to find independently both centers in a very elegant way, but its application is tedious. He confesses that he had to apply it seventy times over a period of 5 years to obtain trustable results. Years earlier, when Kepler arrived to work with Tycho, he found that Tycho and Longomontanus had rejected bisection and somehow had obtained a ratio between eccentricities that, as Kepler himself highlights, happened to be very close to the one Kepler would later find after so much effort. Kepler does not say how Tycho and Longomontanus obtained their parameters and, to the best of my knowledge, there is no single published work that attempts to answer this question. Still, it is a very interesting question to ask how they arrived at values so close to those that took so much pain for Kepler to obtain. Recently, I published a paper describing a method Tycho used for finding Saturn’s parameters. In this paper, I show that by applying this method to the data of Tychonic observations of oppositions, it is possible to arrive at parameters very close to those that we know Tycho found. In this way, I argue that this is the method Tycho applied for obtaining Mars’s parameters. The simplicity of the Tychonic method contrasts with the complexity of Kepler’s.

scholarly journals On the Tidal Prism: The Roles of Basin Extension, Bottom Friction and Inlet Cross-Section

2021 ◽  
Vol 9 (1) ◽  
pp. 88
Author(s):  
Marco Petti ◽  
Sara Pascolo ◽  
Silvia Bosa ◽  
Nadia Busetto
Keyword(s):  
Cross Section ◽  
Bottom Friction ◽  
Static Method ◽  
Tidal Prism ◽  
Empirical Relationships ◽  
Cross Sectional ◽  
Asymptotic Regime ◽  
Static Regime ◽  
The One ◽  
Basin Area

The prism of the Lignano tidal inlet was approximately constant over the last forty years, although the section width has halved. This has led to questions concerning the factors that most influence the tidal prism, and on the applicability of the well-known A–P relationship. A conceptual scheme of the sea–channel–lagoon system has been used to perform a sensitivity analysis of different parameters that characterize both the basin and the inlet cross-section. A 2D hydrodynamic model has been applied to evaluate the prism and compare it to the one derived by a static method, which is the basis of the analytical derivation of the A–P linkage. Three regimes have been found in the prism variability as a function of the basin extension: a linear static regime between prism and basin area; an asymptotic regime in which the prism depends only on the basin bottom friction; and an intermediate one. In addition, the roles of the inlet and channel sizes on the prism value have been investigated. The results, compared to the empirical relationships between the prism and the inlet cross-section, show that a variation in the cross-sectional area does not always corresponds to a change in tidal prism.

scholarly journals Gamma Astrometric Measurement Experiment: testing General Relativity with a small mission

2007 ◽  
Vol 3 (S248) ◽  
pp. 290-291 ◽  
Author(s):  
A. Vecchiato ◽  
M. G. Lattanzi ◽  
M. Gai ◽  
R. Morbidelli
Keyword(s):  
General Relativity ◽  
Solar Eclipse ◽  
Galactic Center ◽  
The Sun ◽  
Measurement Experiment ◽  
The One ◽  
First Time ◽  
Bending Of Light

AbstractGAME (Gamma Astrometric Measurement Experiment) is a concept for an experiment whose goal is to measure from space the γ parameter of the Parameterized Post-Newtonian formalism, by means of a satellite orbiting at 1 AU from the Sun and looking as close as possible to its limb. This technique resembles the one used during the solar eclipse of 1919, when Dyson, Eddington and collaborators measured for the first time the gravitational bending of light. Simple estimations suggest that, possibly within the budget of a small mission, one could reach the 10−6level of accuracy with ~106observations of relatively bright stars at about 2° apart from the Sun. Further simulations show that this result could be reached with only 20 days of measurements on stars ofV≤ 17 uniformly distributed. A quick look at real star densities suggests that this result could be greatly improved by observing particularly crowded regions near the galactic center.

scholarly journals On the scattering of fast neutrons by protons

1947 ◽  
Vol 191 (1025) ◽  
pp. 195-209 ◽  
Keyword(s):  
Angular Distribution ◽  
Cross Section ◽  
Cosmic Ray ◽  
Fast Neutrons ◽  
Meson Mass ◽  
Nuclear Forces ◽  
Total Scattering ◽  
Empirical Results ◽  
Meson Theory ◽  
Total Scattering Cross Section

The features of the scattering of fast neutrons by protons are calculated using the Møller- Rosenfeld version of the meson theory of nuclear forces. The experimental results of Occhialini & Powell are used to check the predicted angular distribution of the scattered particles and to determine the mass of the meson; the meson mass indicated is about 215 electronic masses, which agrees with the mass of cosmic ray mesons. The total scattering cross-section predicted by the theory agrees with the empirical results.

Evidence for the Photoemission Nature of Gd 4f Resonant Photoemission

1998 ◽  
Vol 524 ◽  
Author(s):  
S. R. Mishra ◽  
T. R. Cummins ◽  
W. J. Gammon ◽  
G. D. Waddill ◽  
G. Van der-Laan ◽  
...  
Keyword(s):  
Angular Distribution ◽  
Cross Section ◽  
Photon Energy ◽  
Photoelectron Spectroscopy ◽  
Emission Cross Section ◽  
Linear Dichroism ◽  
Constructive Interference ◽  
Resonant Photoemission ◽  
Magnetic Linear Dichroism ◽  
Spectroscopy Experiment

ABSTRACTThe constructive interference between direct and indirect channels above the absorption threshold of a core level leads to a massive increase in the emission cross section leading to a phenomenon called “resonant photoemission”. Using novel magnetic linear dichroism in angular distribution photoelectron spectroscopy experiment we have tried to understand the nature of the resonant photoemission process in Gd metal. The presence of dichroism in Gd 4f photoemission intensity at a photon energy corresponding to resonant photoemission clearly demonstrates the photoemission-like nature of the resonant photoemission process.

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