X-Ray Emission and Absorption Exercise for Introductory Modern Physics Courses

1974 ◽  
Vol 42 (2) ◽  
pp. 161-166 ◽  
Author(s):  
Walter Kiszenick ◽  
Nathan Wainfan
Keyword(s):  
X Ray ◽  
Physics Courses ◽  
Modern Physics

THE VIP (VIOLATION OF THE PAULI EXCLUSION PRINCIPLE) EXPERIMENT

2007 ◽  
Vol 05 (01n02) ◽  
pp. 299-304 ◽  
Author(s):  
S. BARTALUCCI ◽  
S. BERTOLUCCI ◽  
M. BRAGADIREANU ◽  
M. CARGNELLI ◽  
M. CATITTI ◽  
...  
Keyword(s):  
Pauli Exclusion Principle ◽  
Exclusion Principle ◽  
X Ray ◽  
Preliminary Results ◽  
Forbidden Transition ◽  
Scientific Goal ◽  
Modern Physics ◽  
Lively Debate ◽  
Future Plans

The Pauli Exclusion Principle (PEP) represents one of the fundamental principles of the modern physics and our comprehension of the surrounding matter is based on it. Even if today there are no compelling reasons to doubt its validity, it still spurs a lively debate on its limits, as testified by the abundant contributions found in the literature and in topical conferences. We present a method of searching for possible small violations of PEP for electrons, through the search for "anomalous" X-ray transitions in copper atoms, produced by "fresh" electrons which can decay in a Pauli-forbidden transition to the 1s level, already occupied by two electrons. The VIP Experiment has the scientific goal to improve by four orders of magnitude the present limit on the probability of PEP violation for electrons, bringing it into the 10-30–10-31 region. Preliminary results, together with future plans, are presented.

Modern physics lab experiments using crystal X-ray generators

1999 ◽  
Author(s):  
S. M. Shafroth ◽  
J. D. Brownridge
Keyword(s):  
X Ray ◽  
Lab Experiments ◽  
Modern Physics

Strength of Metals in the Light of Modern Physics

1936 ◽  
Vol 40 (309) ◽  
pp. 586-621 ◽  
Author(s):  
H. J. Gough ◽  
W. A. Wood
Keyword(s):  
Atomic Structure ◽  
Internal Stresses ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Modern Physics ◽  
Correct Understanding ◽  
Development Methods ◽  
First Time ◽  
The Relationship

SummaryThe strengths of the metals at present available to industry are of especial importance to the aeronautical engineer who is also in a position to appreciate the need for greatly improved materials, the absence of which often places restriction on much needed developments. Although the materials of the future may become available by the somewhat fortuitous development methods at present employed, it is undeniable that greatly accelerated developments would result if a correct understanding was obtained of the fundamental characteristics of the cohesion and fracture of metals, of which the former belongs to the field of the atomic physicist.It has been found possible, for the first time, to show that failure under static and fatigue stressing is associated with changes in the crystalline structure which are identical. These changes are (1) a dislocation of the initially perfect grains into large components which vary in orientation from that of the internal grain by amounts up to about 2°,(2) the formation of “crystallites,” approximately 10-4 to 10-5 cm. in size, whose orientation varies widely from that of the original grains, and (3) the presence of severe internal stresses in the crystallites. At fracture, whatever the type of applied stressing, the whole of the specimen behaves to the X-ray beam as a medium of crystallites showing marked lattice distortion and oriented completely at random. X-ray diffraction methods are shown to distinguish clearly between the effects of the application of safe and unsafe ranges of stress; the first method that has been successful in this respect.In order to show the relationship between the new work described and previous work dealing with the use of X-rays in studying the deformation characteristics of metals, a preliminary section of the paper deals with cold-rolling and drawing. A survey is also presented of the present position regarding strength and atomic structure, together with references to various theories regarding the imperfections of crystals as encountered in practice. An introductory section describes briefly the atomic structure of metals, as revealed by X-rays.

scholarly journals Testing General Relativity with black hole X-ray data: a progress report

2021 ◽  
Author(s):  
Cosimo Bambi
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Strong Field ◽  
Weak Field ◽  
Progress Report ◽  
X Ray ◽  
Binary Pulsars ◽  
The Past ◽  
Modern Physics ◽  
New Generation

AbstractEinstein’s theory of General Relativity is one of the pillars of modern physics. For decades, the theory has been mainly tested in the weak field regime with experiments in the Solar System and observations of binary pulsars. Thanks to a new generation of observational facilities, the past 5 years have seen remarkable changes in this field and there are now numerous efforts for testing General Relativity in the strong field regime with black holes and neutron stars using different techniques. Here I will review the work of my group at Fudan University devoted to test General Relativity with black hole X-ray data.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

Some Problems in Understanding the Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 1-9
Author(s):  
A. H. Gabriel
Keyword(s):  
Solar Corona ◽  
Solar Atmosphere ◽  
Theoretical Modelling ◽  
Total System ◽  
Major Advance ◽  
X Ray ◽  
Proper Perspective ◽  
Space Observations

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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