scholarly journals THE REACTION 4He(γ, p)3H, CAUSED BY POLARIZED PHOTONS IN THE GIANT RESONANCE RANGE

2019 ◽  
pp. 21-25
Author(s):  
A.A. Peretiatko ◽  
R.T. Murtazin ◽  
A.F. Khodyachikh
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Diamond Crystal ◽  
Giant Resonance ◽  
Knock Out ◽  
Chamber Method ◽  
The Asymmetry ◽  
The Cross ◽  
Polarized Photons

The reaction of 4He(γ, p)3H in the range of giant resonance was studied by a streamer chamber method in a magnetic field irradiated with polarized photons obtained by plane channeling of electrons by a diamond crystal. The angular and energetic dependences of the asymmetry of the cross section have been measured. The results are explained by the mechanism of direct knock out of nucleons.

scholarly journals CROSS SECTION ASYMMETRY OF THE 12C(γ,p0)11B AND 12C(γ,p1)11B REACTIONS AT PHOTON ENERGIES 40...55MeV

2019 ◽  
pp. 26-37
Author(s):  
D.D. Burdeinyi ◽  
J. Brudvik ◽  
V.B. Ganenko ◽  
K. Hansen ◽  
K. Fissum ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Energy Range ◽  
Cross Section ◽  
Relative Contribution ◽  
Linearly Polarized ◽  
The Asymmetry ◽  
The Cross ◽  
Tagged Photons

The asymmetry of the cross section of the 12C(γ,p0)11B and 12C(γ,p1)11B reactions has been measured in the energy range 40...55MeV using linearly polarized tagged photons of the MAX-lab facility. The asymmetry of the process 12C(⃗γ,p0)11B is Σ ≈ 0.85, that implies one-particle reaction mechanism. The asymmetry of the reaction 12C(⃗γ,p1)11B is smaller, Σ ≈ 0.6...0.7, that may be due to the stronger relative contribution of the 2h−1p mechanism to the dominant one-particle reaction mechanism.

scholarly journals THREE-BODY PHOTODISINTEGRATION OF 4He NUCLEUS BY LINEARLY POLARIZED PHOTONS

2019 ◽  
pp. 11-15
Author(s):  
A.A. Peretiatko ◽  
R.T. Murtazin ◽  
A.F. Khodyachikh
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Production Cross ◽  
Reaction Products ◽  
Azimuthal Distribution ◽  
Proton Production ◽  
Linearly Polarized ◽  
Three Body ◽  
Polarized Photons ◽  
The Magnetic Field

Experimental data are reported from studies of the reaction 4He(γ, pn)d through the use of the streamer chamber placed in the magnetic field and exposed to a linearly polarized photon beam from the electron linac LUE-2000. A structure has been revealed in the momentum distribution of deuterons. Studies were made into the effects of nucleon-deuteron correlation. The azimuthal distribution of reaction products and the asymmetry of proton production cross-section were measured. The obtained data were analyzed in the framework of the quasideuteron model.

The cross-section and angular distribution of the D-D reactions below 50 keV

1953 ◽  
Vol 216 (1124) ◽  
pp. 57-65 ◽  
Keyword(s):  
Angular Distribution ◽  
Total Cross Section ◽  
Cross Section ◽  
Proportional Counter ◽  
Angular Distributions ◽  
Asymmetry Coefficient ◽  
Gas Target ◽  
The Asymmetry ◽  
The Cross ◽  
Bombarding Energy

A thin gas target was used and the particles from the reactions were detected by a proportional counter. The results show that the total cross-section for the two reactions is the same to within 1%, but that the angular distributions of the products are significantly different. The asymmetry coefficient for the reaction D( d , n ) 3 He is given by 0·31 + 0·0058 E , compared with 0·13 + 0·0047 E for reaction D( d , p ) 3 H, where E is the bombarding energy in kilovolts.

Magnetic-field dependence of the cross section formJmixing in2P1/2Cs and Rb atoms

1994 ◽  
Vol 49 (6) ◽  
pp. 4540-4548 ◽  
Author(s):  
W. Kedzierski ◽  
Ju Gao ◽  
W. E. Baylis ◽  
L. Krause
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
The Cross

scholarly journals The Reduction of Welding Current Asymmetry in Multispot Welding Machines by Differentiating the Cross-Section of Welding Machine Arms

2020 ◽  
pp. 37-46
Author(s):  
Mariusz Stępień ◽  
Zygmunt Mikno
Keyword(s):  
Structural Material ◽  
Cross Section ◽  
Cross Sections ◽  
Welding Current ◽  
Weld Nugget ◽  
Welding Machine ◽  
The Asymmetry ◽  
The Cross

The article discusses the analysis of the propagation of current in resistance multispot welding machines and the adjustment of the cross-section of the welding machine arms aimed to compensate the asymmetry of welding current in individual welds. The analysis involved the effect of the length of multispot welding machines where the span of the arms (distance between welds) amounted up to 2 m, the arms were characterised by various cross-sections and the structural material was characterised by various resistivity (resulting from changes in temperature). The analysis was performed in relation to welding machines using a nominal welding current of 5 kA. The tests made it possible to determine the effect of changes in the value of current on the cross-section of the weld nugget.

scholarly journals Rotating magnetic field effect on convection and its stability in a horizontal cylinder subjected to a longitudinal temperature gradient

2010 ◽  
Vol 664 ◽  
pp. 108-137 ◽  
Author(s):  
D. V. LYUBIMOV ◽  
A. V. BURNYSHEVA ◽  
H. BENHADID ◽  
T. P. LYUBIMOVA ◽  
D. HENRY
Keyword(s):  
Magnetic Field ◽  
Temperature Gradient ◽  
Prandtl Number ◽  
Cross Section ◽  
Rotating Magnetic Field ◽  
Shear Mode ◽  
Convective Flows ◽  
Longitudinal Temperature Gradient ◽  
Longitudinal Temperature ◽  
The Cross

A rotating magnetic field (RMF) is used in crystal growth applications during the solidification process in order to improve the crystal quality. Its influence on the convective flows in molten metals and on their stability is studied here in the case of a horizontal infinite cylindrical channel subjected to a longitudinal temperature gradient. The steady convective flows, which correspond to the usual longitudinal counterflow structure, with four vortices in the cross-section for non-zero Prandtl number, Pr, are modified by the RMF (parametrized by the magnetic Taylor number Tam). For zero Prandtl number, the flow in the cross-section corresponds to circular streamlines and the longitudinal flow structure is moved in the direction of the magnetic field rotation, with a decrease in its intensity and an asymptotic variation as 1/Tam. For non-zero Prandtl numbers, depending on the respective values of Tam on one side and Prandtl and Grashof numbers on the other side, different structures ranging from the circular streamlines with transport by rotation of the longitudinal velocity and the temperature field, to the more usual counterflow structure almost insensitive to the RMF with four cross-section vortices, can be obtained. The decrease in the flow intensity with increasing Tam is also delayed for non-zero Pr, but the same asymptotic limit is eventually reached. The stability analysis of these convective flows for Tam = 0 shows a steep increase of the thresholds around Pr = Prt,0 ≈ 3 × 10−4, corresponding to the transition between the usual counterflow shear mode and a new sidewall shear mode. This transition is still present with an RMF, but it occurs for smaller Pr values as Tam is increased. Strong stabilizing effects of the rotating magnetic field are found for Pr < Prt,0, particularly for Pr = 0 where an exponential increase of the threshold with Tam is found. For Pr > Prt,0 (i.e. in the domain where the sidewall instability is dominant), in contrast, the stabilization by the RMF is weak.

scholarly journals Radial distribution of electrons rotation moment in hall effect and plasma-ion thrusters

2021 ◽  
pp. 28-34
Author(s):  
Zongshuai Guo
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Cross Section ◽  
Radial Distribution ◽  
Electric Propulsion ◽  
Mirror Reflection ◽  
Radial Magnetic Field ◽  
Ion Thrusters ◽  
Wall Conductivity ◽  
The Cross

The subject matter of the article is the radial distribution of electrons movement parameters inside electric propulsion thrusters with closed electrons drift. The radial magnetic field in Hall effect thrusters is the limits the axial flow of electrons because of interaction with azimuth electron current. In turn, this azimuth current exists as a result of rivalry between the attempt of the magnetic field to transform electrons current completely closed one and the loss of electrons rotation moment in collisions. Similar processes take place in the ionization chamber of plasma-ion thrusters with the radial magnetic field. The attempts to estimate electrons parameters through only collisions with ions and atoms inside volume have given the value of axial electrons current much lower than really being. This phenomenon is called anomalous electrons conductivity, which was tried to be explained as a consequence of various effects including "near-the-wall-conductivity", which was explained as a result of non-mirror reflection of electrons from the Langmuir layer near the walls of the thruster channel. The disadvantage of this name is the fact that the reflection of the electron occurs before reaching the surface from the potential barrier at the plasma boundary with any environment: the wall, but also with the environment vacuum. The potential distribution in the Langmuir layer is non-stationary and inhomogeneous due to the presence of so-called plasma oscillations. The definition of "conductivity" is just as unfortunate in this name, because the collisions are always not a factor of conductivity, but on the contrary – of resistance. The goal is to solve the task of electrons rotation moment distribution in the thruster channel. The methods used are the formulation of the kinetic equation for electrons distribution function over the velocities, radius, and projections of the coordinates of the instantaneous center of cyclotron rotation; solution of this equation and finding with its use the distribution of the gas-dynamic parameters of electrons along the cross-section of the channel. Conclusions. A mathematical model of electrons rotation moment dynamics is proposed, which allows using plasma-dynamics equations to analyze its distribution along the cross-section of thruster channel and to estimate the effect of "near-the-wall-conductivity" using appropriate boundary conditions.

scholarly journals Collision of a Positron with the Capture of an Electron from Lithium and the Effect of a Magnetic Field on the Particles Balance

Chemosensors ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 45
Author(s):  
Elena V. Orlenko ◽  
Alexandr V. Evstafev ◽  
Fedor E. Orlenko
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Cross Section ◽  
Dynamic Equilibrium ◽  
Mass Effect ◽  
Alpha Particles ◽  
Exchange Effects ◽  
The Cross ◽  
Living Tissues ◽  
Comparison Of The Results

The processes of scattering slow positrons with the possible formation of positronium play an important role in the diagnosis of both composite materials, including semiconductor materials, and for the analysis of images obtained by positron tomography of living tissues. In this paper, we consider the processes of scattering positrons with the capture of an electron and the formation of positronium. When calculating the cross-section for the capture reaction, exchange effects caused by the rearrangement of electrons between colliding particles are taken into account. Comparison of the results of calculating the cross-section with a similar problem of electron capture by a proton showed that the mass effect is important in such a collision process. The loss of an electron by a lithium atom is more effective when it collides with a positron than with a proton or alpha particles. The dynamic equilibrium of the formation of positronium in the presence of a strong magnetic field is considered. It is shown that a strong magnetic field during tomography investigation shifts the dynamic equilibrium to the positronium concentration followed by positron annihilation with radiation of three gamma-quants.

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