scholarly journals Atomic Concealment Due to Loss of Coherence of the Incident Beam of Projectiles in Collision Processes

Atoms ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 5
Author(s):  
Raúl O. Barrachina ◽  
Francisco Navarrete ◽  
Marcelo F. Ciappina
Keyword(s):  
Cross Section ◽  
Coherence Length ◽  
Incident Beam ◽  
Experimental Results ◽  
Interference Effects ◽  
Strong Decrease ◽  
Collision Processes ◽  
The Cross ◽  
Loss Of Coherence

In the study of collision processes, a series of conditions is usually assumed. One of them is that the beam of projectiles is coherent in lengths greater than those of the targets against which it strikes. However, recent experimental results and theoretical analyzes have shown that this assumption can not only fail, but that it is possible to manipulate the coherence length experimentally to go from a coherent situation to an incoherent one. The most conspicuous and studied manifestation of such loss of coherence is the disappearance of interference effects. However, in the present work we show that a strong decrease can also occur in the magnitude of the cross section, not only differential but also total, due to an atomic concealment effect.

The influence of the nuclear and atomic form factors on the muon bremsstrahlung cross section

1968 ◽  
Vol 46 (10) ◽  
pp. S377-S380 ◽  
Author(s):  
A. A. Petrukhin ◽  
V. V. Shestakov
Keyword(s):  
Form Factor ◽  
Cross Section ◽  
Born Approximation ◽  
Form Factors ◽  
Experimental Results ◽  
Simple Analytical Expression ◽  
Nuclear Form Factor ◽  
The Cross ◽  
Atomic Electrons ◽  
Bremsstrahlung Process

The cross section for the muon bremsstrahlung process is calculated as a function of the nuclear form factor in the Born approximation following the Bethe and Heitler theory. The influence of the nuclear form factor is greater than that taken by Christy and Kusaka. The simple analytical expression for the effect of the screening of the atomic electrons is found. The influence of a decrease in the cross section upon the interpretation of some experimental results is estimated.

Experiments on the reaction T( d , n ) 4 He I. The 90° cross-section

1951 ◽  
Vol 204 (1079) ◽  
pp. 488-499 ◽  
Keyword(s):  
Cross Section ◽  
Heavy Water ◽  
Incident Beam ◽  
Absolute Magnitude ◽  
Alpha Particles ◽  
Low Energy ◽  
Energy Relation ◽  
Conventional Theory ◽  
Simultaneous Observation ◽  
The Cross

The 90° cross-section of the reaction 3 1 H( d , n ) 4 2 He has been investigated over the energy range 100 to 200 keV (energy of bombarding triton) using the 200 keV accelerating set of the establishment. Two methods have been used. As a preliminary experiment the yield of alpha-particles from a thick heavy-ice target was measured per unit charge of incident beam, as a function of deuteron energy, and the variation of cross-section deduced from the gradient of this excitation curve and the range energy relation for tritons in heavy water. Secondly, a comparison was made between the yield of alpha-particles from the D-T reaction and the yield of protons from the D-D reaction when a beam containing both deuterons and tritons was passed through a heavy-water vapour target. (The energy loss in this target was calculated as only a few hundred electron volts.) To do this a simultaneous observation was made of the protons and alpha-particles using the same counter. The values obtained for the cross-section have been compared with the resonance formulae given by Bretscher & French (1949) and by Tascbek, Everhart, Gittings, Hemmendinger & Jarvis (1948) and have been found to be in disagreement with formulae of this type. From considerations of the absolute magnitude of the cross-section it has been deduced that no conventional theory postulating reaction at a distance equal to the sum of the nuclear radii (cf. Konopinski & Teller 1948) will be able to explain this reaction. The evidence for a low-energy resonance (Allan & Poole 1949) is thought to be inconclusive.

Behavior of porosity in billet during rolling process of rail

2019 ◽  
Vol 116 (6) ◽  
pp. 607 ◽  
Author(s):  
Rong Cheng ◽  
Jiongming Zhang ◽  
Liangjin Zhang ◽  
Haitao Ma
Keyword(s):  
Simulation Model ◽  
Cross Section ◽  
Rolling Process ◽  
Experimental Results ◽  
Short Cracks ◽  
Industrial Experiments ◽  
Isosceles Trapezoid ◽  
The Cross

Unlike traditional rolling processes, reduction of rolling process of rail is along two vertical directions and the broadening of rolled piece is controlled. In this study, industrial experiments and a simulation model of the rolling process of rail were conducted to investigate the behaviors of porosities in billet during the rolling process of rail. The experimental and simulated results revealed that porosities moved toward the center on the cross section of the rolled piece and the porosities region reduced from a rectangle with the size (76.7 × 93.3 mm) to an isosceles trapezoid with the size {(12.8 + 18.5 mm) × 47.2 mm} during the rolling process of rail. The shapes of the porosities changed from circles with the diameters smaller than 6 mm to short cracks with the lengths shorter than 10 mm on the cross section. The two vertical reduction directions and the controlled broadening of rolled piece both counted against the closure of porosity. The simulated results were mostly in agreement with the experimental results.

scholarly journals ANALYSIS OF PERMEABLE BREAKWATERS

1986 ◽  
Vol 1 (20) ◽  
pp. 155
Author(s):  
Hitoshi Murakami ◽  
Yoshihiko Hosoi ◽  
Yoshitaka Goda
Keyword(s):  
Cross Section ◽  
Water Exchange ◽  
Water Concentration ◽  
Wave Action ◽  
Theoretical Solution ◽  
Experimental Results ◽  
Concentration Change ◽  
Vertical Slit ◽  
Transmission Coefficients ◽  
The Cross

This paper discusses the characteristics of hydraulic and water exchange due to the wave action against vertical slit-type breakwaters. The theoretical solution of the reflection and the transmission coefficients for the breakwater models is compared with the experimental results. Furthermore, the water exchange discharge and the water concentration change through the gap of the permeable breakwater are examined experimentally. Finally the most effective geometry of the cross section is suggested for the breakwaters used here.

scholarly journals The Ovalisation of Steel Circular Hollow Sections under Bending

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
Manahel Sh. Khalaf ◽  
Amer M. Ibrahim
Keyword(s):  
Cross Section ◽  
Local Buckling ◽  
Bending Moment ◽  
Thickness Ratio ◽  
Experimental Results ◽  
Experimental Program ◽  
Specimen Length ◽  
Specimen Cross Section ◽  
The Cross

This paper investigates the ovalisation behavior of the Steel Circular Hollow Sections (CHSs) when subjected to bending moment. The experimental program included testing of ten specimens in four groups in order to examine the influence of changing the diameter, thickness, length and the presence of openings on the ovalisation phenomenon of these specimens.The experimental results showed that the ovalisation of the specimen cross-section appears clearly when the diameter to thickness ratio (D/t) is ranging from 17 to 50, while the ovalisation of the specimens that have D/t ratio greater than 50 is very little or unclear because the instability of these specimens are controlled by the local buckling. In addition, the change of the specimen length and the presence of openings didn’t cause the cross-section ovalisation

Influence of Cross-Section Distortion on the Bending Vibration of Thin-Walled Beams of H Section

1964 ◽  
Vol 6 (3) ◽  
pp. 211-218 ◽  
Author(s):  
A. D. S. Barr ◽  
T. Duthie
Keyword(s):  
Differential Equations ◽  
Cross Section ◽  
Reasonable Agreement ◽  
Experimental Results ◽  
Hamilton’S Principle ◽  
Hamilton's Principle ◽  
Bending Vibration ◽  
Cross Sectional ◽  
Thin Walled ◽  
The Cross

Approximate differential equations describing the bending vibration of beams of thin-walled H section, in which the distortion of the cross-section in its own plane is taken into account, are derived from Hamilton's principle using an assumed form for the cross-section deformation. Only the simplest of the cross-sectional deformation configurations which will couple with ordinary bending is considered. The variation with wavelength of the two spectra of frequencies which result from this coupling of the bending and cross-sectional motions is shown for several section geometries. Theoretical curves show reasonable agreement with experimental results from free beams.

scholarly journals Cross-section measurements for disintegrations produced by deuterons in the heavy elements

1942 ◽  
Vol 180 (982) ◽  
pp. 321-332 ◽  
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Experimental Results ◽  
Heavy Elements ◽  
Nuclear Radius ◽  
The Cross ◽  
Gold Mercury

The cross-sections have been measured for reactions produced by deuterons in platinum, gold, mercury, thallium, lead, bismuth, thorium and uranium, using deuterons of 9 MeV energy from the Cavendish cyclotron. The observed values of σ for the ( d, p ) reaction vary from 30 x 10 -27 cm. 2 for platinum to 5 x 10 -27 cm. 2 for uranium. The values for the ( d, n ) reaction are about one-fifth of those for the ( d, p ) reaction. Calculations of the cross-sections to be expected on theoretical grounds, have been made for two different values of the standard nuclear radius R 0 , namely, 2.0 x 10 -13 and 1.47 x 10 -13 cm. The experimental results are shown to favour the lower of these values.

Experimental results on the cross section for π− πo → π− ωo

1963 ◽  
Vol 5 (3) ◽  
pp. 209-211 ◽  
Author(s):  
L. Bondàr ◽  
E. Keppel ◽  
G. Kraus ◽  
W.P. Dodd ◽  
B. Tallini ◽  
...  
Keyword(s):  
Cross Section ◽  
Experimental Results ◽  
The Cross

Steady long slender droplets in two-dimensional straining motion

1979 ◽  
Vol 91 (3) ◽  
pp. 401-414 ◽  
Author(s):  
E. J. Hinch ◽  
A. Acrivos
Keyword(s):  
Cross Section ◽  
Experimental Results ◽  
Recent Analysis ◽  
Two Dimensional ◽  
Axisymmetric Case ◽  
Hyperbolic Flow ◽  
Theoretical Criterion ◽  
Theoretical Predictions ◽  
The Cross ◽  
Good Agreement

The recent analysis by Acrivos & Lo (1978) concerning the breakup of a long slender droplet in an axisymmetric straining motion is extended to the case of a two-dimensional hyperbolic flow. It is found that, although the cross-section of the droplet becomes significantly non-circular, the theoretical criterion for breakup is effectively the same as in the axisymmetric case. The theoretical predictions are in good agreement with the available experimental results.

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