The relative absorbing powers of the L-levels for radiation of varying wave-length

1924 ◽  
Vol 22 (3) ◽  
pp. 379-392 ◽  
Author(s):  
H. W. B. Skinner
Keyword(s):  
Absorption Coefficient ◽  
Wave Length ◽  
The Other ◽  
X Rays ◽  
A Value ◽  
The Law ◽  
Absorption Wave

1. Changes in the relative intensities of the lines in the fluorescentL-spectrum of Cerium excited by radiation of various wave-lengths have been observed.2. These results imply a change in the relative absorbing powers of the threeL-levels as the wave-length of the absorbed radiation diminishes from a value just below the absorption wave-length of theL-levels to a value considerably below. The absorbing power of theLI-level becomes increased relative to the absorbing powers of the otherL-levels as the wave-length diminishes. The results agree with those published by H. Robinson in a recent paper.3. These results imply a breakdown of the law that μ/λ3is a constant (where μ is the absorption coefficient of X-rays of wave-length λ) as applied to theindividual L-levels of an element.4. A comparison is made between the above results, and some results on the relative absorbing process of theL-levels obtained by Ellis and Skinner from β-ray spectra.

scholarly journals The absorption of hard monochromatic γ-radiation

1930 ◽  
Vol 128 (807) ◽  
pp. 345-359 ◽  
Keyword(s):  
Absorption Coefficient ◽  
High Frequency ◽  
Wave Length ◽  
Low Frequency ◽  
Photoelectric Effect ◽  
Fourth Power ◽  
X Rays ◽  
Photoelectric Absorption ◽  
Initial Direction ◽  
Γ Radiation

Energy may be removed from a beam of γ -rays traversing matter by two distinct mechanisms. A quantum of radiation may be scattered by an electron out of its initial direction with change of wave-length, or it may be absorbed completely by an atom and produce a photoelectron. The total absorption coefficient, μ, is defined by the equation d I/ dx = -μI, and is the sum of the coefficients σ and τ referring respectively to the scattering and to the photoelectric effect. For radiation of low frequency, such as X-rays, the photoelectric absorption is very much more important than the absorption due to scattering, and many experiments have shown that the photoelectric absorption per atom varies as the fourth power of the atomic number and approximately as the cube of the wave-length. For radiation of high frequency, such as the more penetrating γ -rays, the photoelectric effect is, even for the heavy elements, smaller than the scattering absorption; and, since the scattering from each electron is always assumed to be independent of the atom from which it is derived, it is most convenient to divide μ. defined above by the number of electrons per unit volume in the material and to obtain μ e the absorption coefficient per electron.

scholarly journals Economic Efficiency in Economic Analysis of Law

2017 ◽  
Vol 3 (15) ◽  
Author(s):  
Tomasz Famulski
Keyword(s):  
Economic Efficiency ◽  
Critical Analysis ◽  
Point Of View ◽  
The Other ◽  
Legal Regulations ◽  
Economic Analysis Of Law ◽  
Practical Point ◽  
A Value ◽  
The Law ◽  
Fundamental Value

The aim of the article is to identify the category of economic efficiency on the grounds of L&E. According to the primary thesis of L&E economic efficiency is a fundamental legal value. The study discusses said thesis. On one hand, the controversy surrounding the thesis stem from lack of its unequivocal understanding. On the other, law has been functioning for centuries, while the question of its economic efficiency has only been raised for a few decades. Fundamental value, which has always been associated with law, is justice. It follows that the issue of various approaches to the relation between economic efficiency and justice in L&E is considered. Critical analysis of the literature allows to formulate arguments for and against each of these values in enacting and enforcing the law. Significant differences in various approaches to this matter are identified. Simultaneously, the assumption that efficiency is a value realized in the law beside justice is considered to be correct. The issue raised is important from the practical point of view. A theoretical consensus would support formulating a model, which would allow assessment of legal regulations based on criteria of economic efficiency and justice.

scholarly journals The reflection of X-rays by crystals. (II.)

1913 ◽  
Vol 89 (610) ◽  
pp. 246-248 ◽  
Keyword(s):  
Crystal Structure ◽  
Rock Salt ◽  
Royal Society ◽  
Wave Length ◽  
The Other ◽  
X Rays ◽  
Elementary Volume ◽  
Four Corners ◽  
Homogeneous Beam

This note is a supplement to a paper on the reflection of X-rays by crystals which has been recently communicated to the Royal Society. It is there shown that the wave-length of a homogeneous beam of X-rays can be found accurately in terms of the spacing of the elements of a crystal. There has been some doubt as to the actual arrangement of the atoms in the crystal and in consequence it was not possible in the paper quoted to draw any final conclusions as to wave-length values. From the work now described by W. L. Bragg it appears that the reflection phenomena lead to a more definite knowledge of crystal structure, and we may now complete various quantitative determinations. The elementary volume in rock-salt is a cube with 1 atom of sodium at each of four corners and 1 atom of chlorine at each of the other four. In other words the number of elementary volumes in any space of measurable dimensions is equal to the number of atoms in that space.

scholarly journals A critical-absorption photometer for the study of the Compton effect

1928 ◽  
Vol 119 (783) ◽  
pp. 526-530
Keyword(s):  
Absorption Coefficient ◽  
Wave Length ◽  
Light Element ◽  
Compton Effect ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Length Changes ◽  
Absorption Measurements ◽  
Ray Scattering

That a change of wave-length occurs in X-ray scattering was first indicated by absorption measurements with the ionisation chamber, which showed that the absorption coefficient of a light element like aluminium was slightly greater for the scattered than for the primary X-rays. Later more conclusive and direct evidence was obtained when spectrometric analysis of the scattered X-rays was made first by the ionisation and afterwards by the photographic method. This analysis disclosed the existence of an unshifted as well as the shifted line, and showed also that the latter becomes relatively more prominent with diminishing wave-length and lower atomic number of the scattering element. After the main features of the Compton effect were established by means of spectrometric measurements, however, absorption measurements with the ionisation method have again been employed for a detailed study of the phenomenon, for such measurements are much quicker than the spectrum experiments, where the final energy available is much smaller on account of the double scattering involved. As mentioned above, the absorption measurements were based on the slight increase in the absorption coefficient of a light element when the wave-length changes from the unmodified to the modified value. The much larger and sudden diminution in absorption of X-rays when the frequency is altered from the short to the long wave-length side of the critical K-absorption limit of the element used as a filter, furnishes us with an easy and convenient method of exhibiting the wave-length change in X-ray scattering. In the present paper will be described a photographic wedge photometer based on this principle, which enables the characteristics of the Compton effect to be readily observed. It may be pointed out that the same idea could no doubt be utilised also in connection with the ionisation measurements of the Compton effect.

scholarly journals The Urgency of the Maqāṣid Al-Syarī‘Ah in Reasoning Islamic Law

2019 ◽  
Vol 1 (2) ◽  
pp. 117-123
Author(s):  
Alimuddin
Keyword(s):  
Islamic Law ◽  
The Other ◽  
A Value ◽  
Other Hand ◽  
Human Need ◽  
Basic Concepts ◽  
The Law

This paper aims to present several theories about how important to understand maqāṣid al-syarī‘ah when someone wants to study a law in Islam, someone cannot be separated from that context. Maqāṣid al-syarī‘ah is a barometer or the main standard of consideration in the formulation of shari'ah with the aim of benefit the Ummah, and Islam consistently makes  maqāṣid al-syarī‘ah in all its rules. The thinking of Ibn ‘Āsyūr about maqāṣid is built on this principle, that it’s imperative to accept the concept of ta‘līl. The theory of maqāṣid rests on three basic concepts; (a). Maqāṣids are sometimes qath‘ī and ḍannī (assumptive). (b). Maqāṣid ‘āmmah and khaṣṣhah (c). Al-maqām, al-istiqrā ’and distinguish between waṣilah and purpose in the application of fiqh law. Every phenomenon that has great potential for maslahah it can be stated to be included in the maqāṣid al-syarī‘ah. On the other hand the human need is not to know the maqāṣid al-syāri‘ itself, but to find a law for a new case that has no prescribed text. Ontology of maqāṣid al-syarī'at al-khāssah is also a value, because knowing the law for that case is complete with the text, now the needed for a new case, so the ontology of maqāṣid al-syarī'ah in this dimension is a transcendent value to refer when conducting tahqīqal-manāt.

scholarly journals III. Transmission of sunlight through the Earth’s atmosphere

1887 ◽  
Vol 42 (251-257) ◽  
pp. 170-172
Keyword(s):  
Wave Length ◽  
Solar Spectrum ◽  
Transmitted Wave ◽  
The Other ◽  
Earth’S Atmosphere ◽  
Minimum Value ◽  
Subsequent Investigation ◽  
Earth's Atmosphere ◽  
The Law ◽  
Made In

The observations were made by means of the colour photometer which General Festing and himself introduced last year, and which they described in the Bakerian Lecture for 1886. They extended over more than a year, the object being to ascertain the intensity of the different rays in the solar spectrum after passing through various thicknesses of the atmosphere. Owing to the unpromising results obtained by Langley with his bolometer experiments, it was not anticipated that the variation in the intensities of the different rays would obey any law, but subsequent investigation showed that as a rule the intensity of any ray obeyed the law enunciated by Lord Rayleigh, in that I' = I ε - kxλ -4 , where I and I' are the initial and transmitted wave-lengths, x the thickness of the medium through which the ray passed, and k a constant, λ being the wave-length. The standard illuminating value of the spectrum was taken from observations made in Switzerland at 8000 feet altitude on September 15 at noon. The other observations were made at South Kensington. It was found that with the wind in the proper quarter the sky at the latter place was as pure in colour as in the country, and that measures made on the days on which there was apparently no haze gave results which when combined together gave a minimum value for k of 0·0013. A mean of the results showed that k = 0·0017.

scholarly journals Experiments on the diffraction of cathode rays.—II

1928 ◽  
Vol 119 (783) ◽  
pp. 651-663 ◽  
Keyword(s):  
Thin Film ◽  
Diffraction Pattern ◽  
Discharge Tube ◽  
Photographic Plate ◽  
Wave Length ◽  
The Other ◽  
X Rays ◽  
Spark Gap ◽  
De Broglie Waves ◽  
Considerable Length

§ 1. The following paper is an account of further experiments which have been made on the lines of those described in these ' Proceedings ’ (vol. 117, p. 600), and largely with the same apparatus. A beam of cathode rays passing normally through a very thin film of metal was found to produce a pattern of concentric rings on a photographic plate about 30 cm. away. These could be explained as a diffraction pattern due to the de Broglie waves of the electron, the atoms of the metal crystals being the diffracting system. In the present paper several points of uncertainty are cleared up, and the work extended to other cases. § 2. As mentioned in a note at the end of the previous paper, the discrepancy of 6 per cent, between the values of the crystal constants of aluminium and gold determined by X-rays, and those found by applying the de Broglie theory to the diffraction rings formed by the cathode rays, has now been explained. It was due to an error in the measurement of the energy of the cathode rays, and hence their wave-length. The energy was measured by a spark-gap connected in parallel with the discharge tube. In the earlier measurements a considerable length of leads and a rectifying valve were included with the discharge tube, and it now appears that an appreciable fraction of the potential fall occurred in these. When two spark-gaps were used, one connected as before, and the other directly across the discharge, there was 1-2 mm. difference in the readings. The following table shows the values of P, the voltage; D, the diameter of the ring corresponding to reflection from the (2, 0, 0) plane; and D√P (1 + P e /1200 m 0 c 2 ), which latter quantity should be constant for any one metal on the de Broglie theory (see previous paper, p. 603). The factor in brackets is the relativity correction, and in the experiments in question never differs from unity by more than 3 per cent.

scholarly journals On the absorption of X-rays in copper and aluminium

1918 ◽  
Vol 94 (664) ◽  
pp. 567-575 ◽  
Keyword(s):  
Absorption Coefficient ◽  
Electromagnetic Radiation ◽  
Experimental Work ◽  
Atomic Structure ◽  
Wave Length ◽  
X Rays ◽  
Absorption Coefficients

Much experimental work has been directed towards the determination of the absorption coefficients of X-rays in elements—especially with respect to the relation existing between the absorption coefficient and the wave-length—owing to the importance of the bearing of the results on the theories of electromagnetic radiation and atomic structure. Nevertheless, on account of the experimental difficulties encountered in this work, serious discrepancies appear among the results of different observers. The method described below appears to offer a reliable and accurate means of measuring the absorption coefficients of homogeneous X-rays in various materials and the wave-lengths of the rays employed. Among the difficulties experienced in the experimental arrangements, two of the chief are:— ( a ) The heterogeneity of the source. ( b ) The variations in intensity of the source.

scholarly journals The absorption of X-rays

1918 ◽  
Vol 94 (664) ◽  
pp. 510-524 ◽  
Keyword(s):  
Absorption Coefficient ◽  
Atomic Absorption ◽  
Atomic Number ◽  
Wave Length ◽  
Fourth Power ◽  
X Rays ◽  
Absorption Coefficients ◽  
Characteristic Radiation ◽  
Crystal Face ◽  
X Ray

Introduction . —Previous to the discovery of the behaviour of X-rays with regard to crystals, the most homogeneous radiation obtainable was that of the characteristic radiation of an element which is excited when that element is exposed to X-radiation of suitable hardness. These characteristic radiations are now found, however, by the new method of analysis, to be constituted of a number of radiations of different wave-lengths. Moseley, shortly after the discovery of the reflection of X-rays, showed that the characteristic radiations of most of the metals he examined consisted of two prominent wave-lengths; Bragg later found that, in the case of rhodium, palladium and silver, each of these lines could be further resolved into two components. Hence the spectra of the characteristic radiation of the K series of these elements consist of at least four different wave-lengths. The analysis of a beam of X-rays into its constituent radiations by reflection at a crystal face provides a means, therefore, of obtaining radiation of a definite wave length and of such intensity as to enable its absorption coefficient in different materials to be accurately measured. Bragg and Pierce have already measured the absorption coefficients of the two most prominent lines in the spectra of the elements Rh, Pd and Ag, in a number of metals. To make the absorption coefficient more directly comparable with other atomic characteristics, they gave their results in the form of atomic absorption coefficients: the atomic absorption coefficient expresses the proportion of the energy of an X-ray pencil which is absorbed in crossing a surface on which lies one atom to every square centimetre. The ordinary mass absorption coefficient can be calculated from this quantity by dividing it by the mass of the absorbing atom. The experimental results showed that the ratio of two absorption coefficients is independent of the wave-length of the radiation over considerable ranges, a result previously deduced by Barkla from his experiments; also, that the atomic absorption coefficient is proportional to the fourth power of the atomic number of the absorber.

Sign in / Sign up

Export Citation Format

Share Document