scholarly journals Remarks on the anomalous scattering of α-particles from the quantum mechanical point of view

1930 ◽  
Vol 127 (806) ◽  
pp. 671-677 ◽  
Keyword(s):  
Cross Section ◽  
Point Of View ◽  
Light Nuclei ◽  
Fourth Power ◽  
Quantum Mechanical ◽  
Anomalous Scattering ◽  
Particle Scattering ◽  
Scattering Angle ◽  
Coulomb Law ◽  
Α Particles

1. It has been established experimentally by Bieler and Rutherford and Chadwick that α-particle scattering by light nuclei does not obey the Rutherford formula if the velocity of the incident particles be sufficiently large (of the order 2 × 10 9 cm. per second). Bieler showed that the scattering becomes less than the classical value for moderate angles (up to 70° scattering angle), while Rutherford and Chadwick found that it increases again for 135° scattering angle. It is at once obvious that these results indicate a departure from the Coulomb law of force, and various laws have been invoked to explain the devia­tions. Thus Bieler showed how the inverse fourth power law was capable of explaining his results, and he found the radius of the neutral surface of the nucleus to be 3⋅44 × 10 -13 cm. Hardmeier used an inverse fifth power polarisation law and was able to explain the increase again at high velocities. However it is desirable to consider the validity of these calculations from the standpoint of the new mechanics. 2. Dimensional Considerations .—Consider scattering by a centre of force exerting a potential F r -n . This scattering will depend not only on the mass m , and velocity v of the incident particles, and on F, but also on Planck’s constant h . The possible dependence on h is not taken into account in any of the above attempts to explain anomalous scattering. Put the scattering cross section proportional to h s v t m u F w .

scholarly journals The scattering of α -particles in helium

1939 ◽  
Vol 172 (951) ◽  
pp. 559-567 ◽  
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Potential Barrier Height ◽  
Light Nuclei ◽  
Coulomb Scattering ◽  
Particle Scattering ◽  
Broad Level ◽  
Resonances In Scattering ◽  
Α Particles

In a previous paper (Devons 1939) the author has discussed the possibility of observing resonance phenomena in the scattering of α -particles by light nuclei, and the experimental results given there show that in general resonances in scattering are observable for light nuclei of atomic number less than about 12 and for α -particle energies about equal to or greater than the potential barrier height. In the case of the scattering by helium nuclei the classical coulomb scattering is very small, and therefore anomalies in the scattering due to excited states of Be 8 , the compound nucleus formed by He 4 and an α -particle, should be comparatively easy to detect. In addition no disintegration is possible with α -particles of the energies used (less than 8.5 MeV), so that if the nucleus Be 8 is formed in an excited state it can only dissociate into two α -particles, and hence the width of any level of Be 8 excited by α -particle scattering in helium will be due practically entirely to elastic scattering. The investigation of the excited states of Be 8 by means of the scattering of α -particles by helium nuclei has a particular interest since the existence of a broad level of Be 8 with an excitation energy of about 3 MeV above the ground state, which is capable of splitting up into two α -particles, is postulated to account for the results of several disintegration experiments.

NEW PHENOMENA IN X-RAY SCATTERING

1930 ◽  
Vol 2 (4) ◽  
pp. 291-293 ◽  
Author(s):  
J. A. Gray ◽  
W. H. Zinn
Keyword(s):  
X Rays ◽  
Particle Scattering ◽  
Scattering Angle ◽  
X Ray ◽  
X Ray Scattering ◽  
New Phenomena ◽  
Α Particles ◽  
Ray Scattering

X rays were scattered by a number of samples of graphite and charcoal in such a way that the scattering increased in intensity as the scattering angle approached zero. In certain cases the scattering at small angles was very similar to the scattering of α-particles; this result cannot be explained easily on the basis of the current views on the nature of X-rays and matter. Experiments are being devised to test what part adsorbed gases play in the phenomena, and to determine whether the scattering at very small angles is a true particle scattering.

scholarly journals Inclusive neutrino-nucleus reaction cross sections at intermediate energies

2020 ◽  
Vol 5 ◽  
pp. 29
Author(s):  
T. S. Kosmas ◽  
E. Oset
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Reaction Cross ◽  
Point Of View ◽  
Electron Neutrino ◽  
Muon Capture ◽  
Light Nuclei ◽  
Experimental Point ◽  
Intermediate Energies ◽  
Reaction Cross Sections

Inclusive neutrino-nucleus reaction cross sections at intermediate energies (20 MeV < Ey < 500 MeV) are calculated throughout the periodic table for the most interesting nu­ clei from an experimental point of view. The method used had previously proved to be very accurate in calculating the induced reaction cross section for T=0 light nuclei (12C and 16O) and in the study of other similar processes like the ordinary muon capture. The electron-neutrino (ve) cross section weighted by the Michel distribution is also discussed in conjuction with the existing experimental results at LAMPF and ΚARMEN.

scholarly journals Semi-Classical Localisation Properties of Quantum Oscillators on a Noncommutative Configuration Space

2015 ◽  
Vol 22 (04) ◽  
pp. 1550021 ◽  
Author(s):  
Fabio Benatti ◽  
Laure Gouba
Keyword(s):  
Phase Space ◽  
Configuration Space ◽  
Classical Limit ◽  
Coherent States ◽  
Point Of View ◽  
Quantum Mechanical ◽  
Wigner Functions ◽  
Quantum Mechanical Oscillators ◽  
Mechanical Oscillators ◽  
Space Noncommutativity

When dealing with the classical limit of two quantum mechanical oscillators on a noncommutative configuration space, the limits corresponding to the removal of configuration-space noncommutativity and position-momentum noncommutativity do not commute. We address this behaviour from the point of view of the phase-space localisation properties of the Wigner functions of coherent states under the two limits.

scholarly journals QUANTUM SINGULARITIES IN STATIC SPACETIMES

2011 ◽  
Vol 20 (05) ◽  
pp. 729-743 ◽  
Author(s):  
JOÃO PAULO M. PITELLI ◽  
PATRICIO S. LETELIER
Keyword(s):  
Quantum Mechanics ◽  
Wave Operator ◽  
Point Of View ◽  
Quantum Mechanical ◽  
Mathematical Framework ◽  
Physical Content ◽  
Dirac Equations ◽  
Quantum Particles ◽  
Klein Gordon ◽  
Quantum Singularities

We review the mathematical framework necessary to understand the physical content of quantum singularities in static spacetimes. We present many examples of classical singular spacetimes and study their singularities by using wave packets satisfying Klein–Gordon and Dirac equations. We show that in many cases the classical singularities are excluded when tested by quantum particles but unfortunately there are other cases where the singularities remain from the quantum mechanical point of view. When it is possible we also find, for spacetimes where quantum mechanics does not exclude the singularities, the boundary conditions necessary to turn the spatial portion of the wave operator to be self-adjoint and emphasize their importance to the interpretation of quantum singularities.

scholarly journals Determining Functional Relations in Multivariate Oceanographic Systems: Model II Multiple Linear Regression

2014 ◽  
Vol 31 (7) ◽  
pp. 1663-1672 ◽  
Author(s):  
Scott J. Richter ◽  
Robert H. Stavn
Keyword(s):  
Cross Section ◽  
Particle Concentration ◽  
Scattering Coefficient ◽  
Mineral Particle ◽  
Particle Scattering ◽  
Multivariate System ◽  
Functional Relationships ◽  
Scattering Cross ◽  
Model Ii Regression ◽  
Organic Particle

Abstract A method for estimating multivariate functional relationships between sets of measured oceanographic, meteorological, and other field data is presented. Model II regression is well known for describing functional relationships between two variables. However, there is little accessible guidance for the researcher wishing to apply model II methods to a multivariate system consisting of three or more variables. This paper describes a straightforward method to extend model II regression to the case of three or more variables. The multiple model II procedure is applied to an analysis of the optical spectral scattering coefficient measured in the coastal ocean. The spectral scattering coefficient is regressed against both suspended mineral particle concentration and suspended organic particle concentration. The regression coefficients from this analysis provide adjusted estimates of the mineral particle scattering cross section and the organic particle scattering cross section. Greater accuracy and efficiency of the coefficients from this analysis, compared to semiempirical coefficients, is demonstrated. Examples of multivariate data are presented that have been analyzed by partitioning the variables into arbitrary bivariate models. However, in a true multivariate system with correlated predictors, such as a coupled biogeochemical cycle, these bivariate analyses yield incorrect coefficient estimates and may result in large unexplained variance. Employing instead a multivariate model II analysis can alleviate these problems and may be a better choice in these situations.

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