Symmetry breaking in statistical nuclear reactions: are two-state-models useful?

1990 ◽  
Vol 337 (1) ◽  
pp. 29-37
Author(s):  
M. Mayer ◽  
A. M�ller ◽  
H. L. Harney
Keyword(s):  
Symmetry Breaking ◽  
Nuclear Reactions ◽  
State Models

scholarly journals Neutrino Cooling of Primordial Hot Regions

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1442
Author(s):  
Konstantin Belotsky ◽  
Mohamed El Kasmi ◽  
Sergey Rubin
Keyword(s):  
Symmetry Breaking ◽  
Lower Limit ◽  
Particle Concentration ◽  
Initial Temperature ◽  
Nuclear Reactions ◽  
Threshold Effect ◽  
Final Temperature ◽  
Hot Matter ◽  
Density Inhomogeneities

The effect of neutrino cooling of possible primary regions filled by hot matter is discussed. Such regions could be obtained from the primordial density inhomogeneities and survive up to the modern epoch. The inhomogeneities could be caused by a symmetry breaking during the inflationary stage. We show that the final temperature of such region should be ∼10 keV provided that the initial temperature is within the interval 10 keV ÷ 100 MeV. The cooling is realized due to the weak nuclear reactions containing n−p transition. The lower limit 10keV is accounted for by suppression of the reactions rates because of the threshold effect and particle concentration decrease.

Symmetry Breaking in Nuclear Reactions: Asymmetry in α+d → 3He + 3H

1986 ◽  
pp. 211-220 ◽  
Author(s):  
M. Bruno ◽  
F. Cannata ◽  
M. D’ Agostino ◽  
M. Frisoni ◽  
H. Herman ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Nuclear Reactions

scholarly journals Long-range order and symmetry breaking in projected entangled-pair state models

2015 ◽  
Vol 92 (15) ◽  
Author(s):  
Manuel Rispler ◽  
Kasper Duivenvoorden ◽  
Norbert Schuch
Keyword(s):  
Symmetry Breaking ◽  
Long Range ◽  
Range Order ◽  
Long Range Order ◽  
State Models ◽  
Pair State

scholarly journals ${\mathbb Z}_N$ symmetry breaking in projected entangled pair state models

2017 ◽  
Vol 50 (36) ◽  
pp. 365001
Author(s):  
Manuel Rispler ◽  
Kasper Duivenvoorden ◽  
Norbert Schuch
Keyword(s):  
Symmetry Breaking ◽  
State Models ◽  
Pair State

scholarly journals Time reversal symmetry breaking effects in resonant nuclear reactions

1995 ◽  
Vol 351 (2) ◽  
pp. 133-136 ◽  
Author(s):  
H. Feshbach ◽  
M. S. Hussein ◽  
A. K. Kerman
Keyword(s):  
Symmetry Breaking ◽  
Time Reversal ◽  
Nuclear Reactions ◽  
Time Reversal Symmetry

Nuclear Processes Related to the Ap Stars and the Heaviest Chemical Elements

1976 ◽  
Vol 32 ◽  
pp. 169-182
Author(s):  
B. Kuchowicz
Keyword(s):  
Nuclear Physics ◽  
Nuclear Reactions ◽  
Chemical Elements ◽  
Fission Products ◽  
Abundance Pattern ◽  
Isotopic Shifts ◽  
Processed Material ◽  
R Process ◽  
Ap Stars ◽  
Nuclear Processes

SummaryIsotopic shifts in the lines of the heavy elements in Ap stars, and the characteristic abundance pattern of these elements point to the fact that we are observing mainly the products of rapid neutron capture. The peculiar A stars may be treated as the show windows for the products of a recent r-process in their neighbourhood. This process can be located either in Supernovae exploding in a binary system in which the present Ap stars were secondaries, or in Supernovae exploding in young clusters. Secondary processes, e.g. spontaneous fission or nuclear reactions with highly abundant fission products, may occur further with the r-processed material in the surface of the Ap stars. The role of these stars to the theory of nucleosynthesis and to nuclear physics is emphasized.

Nuclear Reactions in Deuterium Titanium

1990 ◽  
Vol 48 (2) ◽  
pp. 134-135
Author(s):  
D.M. Vanderwalker
Keyword(s):  
Nuclear Reactions ◽  
Ion Beam ◽  
Exothermic Reaction ◽  
Pure Titanium ◽  
Fundamental Interest ◽  
Transmission Electron ◽  
Iodide Titanium ◽  
A Cell ◽  
After Hours ◽  
Quantity Of Heat

There is a fundamental interest in electrochemical fusion of deuterium in palladium and titanium since its supposed discovery by Fleischmann and Pons. Their calorimetric experiments reveal that a large quantity of heat is released by Pd after hours in a cell, suggesting fusion occurs. They cannot explain fusion by force arguments, nor can it be an exothermic reaction on the formation of deuterides because a smaller quantity of heat is released. This study examines reactions of deuterium in titanium.Both iodide titanium and 99% pure titanium samples were encapsulated in vacuum tubes, annealed for 2h at 800 °C. The Ti foils were charged with deuterium in a D2SO4 D2O solution at a potential of .45V with respect to a calomel reference junction. Samples were ion beam thinned for transmission electron microscopy. The TEM was performed on the JEOL 200CX.The structure of D charged titanium is α-Ti with hexagonal and fee deuterides.

Symmetry breaking in convergent-beam diffraction

1989 ◽  
Vol 47 ◽  
pp. 480-481
Author(s):  
D.J. Eaglesham
Keyword(s):  
Symmetry Breaking ◽  
Point Group ◽  
X Ray Diffraction ◽  
Multiple Diffraction ◽  
Space Groups ◽  
Atomic Displacements ◽  
Small Probe ◽  
Phase Sensitive ◽  
Convergent Beam

Convergent Beam Electron Diffraction is now almost routinely used in the determination of the point- and space-groups of crystalline samples. In addition to its small-probe capability, CBED is also postulated to be more sensitive than X-ray diffraction in determining crystal symmetries. Multiple diffraction is phase-sensitive, so that the distinction between centro- and non-centro-symmetric space groups should be trivial in CBED: in addition, the stronger scattering of electrons may give a general increase in sensitivity to small atomic displacements. However, the sensitivity of CBED symmetry to the crystal point group has rarely been quantified, and CBED is also subject to symmetry-breaking due to local strains and inhomogeneities. The purpose of this paper is to classify the various types of symmetry-breaking, present calculations of the sensitivity, and illustrate symmetry-breaking by surface strains.CBED symmetry determinations usually proceed by determining the diffraction group along various zone axes, and hence finding the point group. The diffraction group can be found using either the intensity distribution in the discs

The evolution of the microstructure of 600 Mev proton irradiated materials

1990 ◽  
Vol 48 (4) ◽  
pp. 1002-1003
Author(s):  
R. Gotthardt ◽  
A. Horsewell ◽  
F. Paschoud ◽  
S. Proennecke ◽  
M. Victoria
Keyword(s):  
Nuclear Reactions ◽  
Dislocation Loops ◽  
Defect Clusters ◽  
Weak Beam ◽  
Stacking Fault Tetrahedra ◽  
Small Defect ◽  
Sufficient Intensity ◽  
Reactor Materials ◽  
Metallic Impurities ◽  
Beam Technique

Fusion reactor materials will be damaged by an intense field of energetic neutrons. There is no neutron source of sufficient intensity at these energies available at present, so the material properties are being correlated with those obtained in irradiation with other irradiation sorces. Irradiation with 600 MeV protons produces both displacement damage and impurities due to nuclear reactions. Helium and hydrogen are produced as gaseous impurities. Other metallic impurities are also created . The main elements of the microstructure observed after irradiation in the PIREX facility, are described in the following paragraphs.A. Defect clusters at low irradiation doses: In specimens irradiated to very low doses (1021-1024 protons.m-2), so that there is no superimposition of contrast, small defect clusters have been observed by the weak beam technique. Detailed analysis of the visible contrast (>0.5 nm diameter) revealed the presence of stacking fault tetrahedra, dislocation loops and a certain number of unidentified clusters . Typical results in Cu and Au are shown in Fig. 1.

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