The Effective Wave-length of γ Rays

Nature ◽  
1925 ◽  
Vol 116 (2910) ◽  
pp. 206-207 ◽  
Author(s):  
D. SKOBELTZYN
Keyword(s):  
Wave Length ◽  
Γ Rays ◽  
Effective Wave

scholarly journals Further experiments on the absorption and scattering of γ-rays

1925 ◽  
Vol 109 (749) ◽  
pp. 206-223 ◽  
Keyword(s):  
Direct Method ◽  
Wave Length ◽  
X Rays ◽  
Short Waves ◽  
General Law ◽  
Direct Measurements ◽  
Wide Range ◽  
Important Direction ◽  
Γ Rays ◽  
Effective Wave

The absorption and scattering of γ-rays by elements has already formed the subject of two papers published recently in these proceedings. The objects of the experiments described in this paper were (1) to extend the absorption measurements, especially in the more important direction of the extremely short waves emitted by RaC, and (2) to make a thorough investigation, with special reference to Compton’s theory, of the scattering by matter of these high-frequency radiations. It was shown in the papers referred to that the absorption of γ-rays from RaB + C, filtered through 1 cm. of lead, is closely expressed by relations similar to those which hold for X-rays. Estimates of the mean-effective wave-length of the beam placed the value at about 0.02 Å. U. Now, it is well known from the crystal analysis of Rutherford and Andrade, and the β-ray magnetic spectra measurements of Ellis, and Ellis, and Skinner, that the γ-rays emitted by radium products cover a wide range of wave-length —roughly, from 1.0 to 0.005 Å. U. It is, however, uncertain whether the very short waves obey the same general laws of absorption as the ordinary X-rays. Direct measurements on a few selected homogeneous rays, though capable of yielding most important results, are unfortunately impracticable. The problem has, therefore, been attacked by the less direct method of measuring accurately the absorption of a complex beam, successively hardened by means of five suitable filters. It will be shown that in every case the absorption of γ-rays obeys the same general law as has already been found. The measurements also throw some light on the spectral distribution of energy in the beam.

scholarly journals Phenomena associated with the anomalous absorption of high energy gamma radiation.—II

1934 ◽  
Vol 143 (850) ◽  
pp. 681-706 ◽  
Keyword(s):  
Gamma Radiation ◽  
Scattered Radiation ◽  
Wave Length ◽  
Large Angle ◽  
High Energy ◽  
Secondary Radiation ◽  
Anomalous Absorption ◽  
Small Thickness ◽  
Energy Gamma ◽  
Γ Rays

In a previous paper we gave an account of an investigation of the secondary radiation produced when different elements are irradiated with the high energy γ-rays of thorium C". The present paper describes an extension of this investigation. It will be reduced that confusion with the ordinary scattered radiation was almost entirely eliminated by examining the secondary radiation in a direction making a large angle with the primary beam, since under these conditions not only is the Compton radiation relatively very much weaker, but in addition it is comparatively soft and is easily absorbed in the radiator itself, or in a very small thickness of absorber, owing to the large increase in wave-length at this large angle of scattering.

scholarly journals β-ray spectra and their meaning

1922 ◽  
Vol 101 (708) ◽  
pp. 1-17 ◽  
Keyword(s):  
Wave Length ◽  
X Rays ◽  
Ernest Rutherford ◽  
Active Atom ◽  
Magnetic Spectrum ◽  
Γ Rays

In a previous paper, I described some measurements of the magnetic spectrum of the β-ravs ejected from various metals by the γ-rays of radium B. These experiments showed that the conversion of monochromatic γ-rays into β-rays was described by the same quantum relation that holds for X-rays and light, and using this knowledge it was found possible to give a complete explanation of the natural β-ray spectrum of radium B. Sir Ernest Rutherford had already shown that the lines in the β-ray spectrum were due in some way to the conversion of monochromatic γ-rays in the same radio active atom that emitted them, and these experiments on the excited spectra now proved that the strong lines were due to the conversion of the γ-rays in the K ring, and the weaker lines to conversion in the L 3 ring. This explanation of the line β-ray spectrum is, by itself, of considerable interest, but of far greater importance is the fact that these experiments give a method of finding the wave-lengths of γ-rays. The shortest wave-length that has been measured by the crystal method is 0·07 Å. U., and at present it seems almost impossible to extend this range much further by this method. Since many radio-active bodies emit γ-rays of shorter wave-length than this any method by which these wave-lengths may be found is important

scholarly journals The absolute energies of the groups in magnetic β-ray spectra

1924 ◽  
Vol 105 (729) ◽  
pp. 60-69 ◽  
Keyword(s):  
Magnetic Field ◽  
Wave Length ◽  
X Rays ◽  
Homogeneous Groups ◽  
Absorption Energy ◽  
Length Measurements ◽  
Γ Rays ◽  
Γ Ray ◽  
The Absolute ◽  
The Difference

Most β-ray bodies emit several homogeneous groups of β-rays, and the energies of the electrons forming these groups may be found from the deflection they suffer in a magnetic field. Various experiments have shown that these groups are due to the conversion, according to the quantum relation, of γ-rays in the different electronic levels of the atom. In fact, the energy of any group is of the form E 1 = hv — (absorption energy of level). Two β-ray groups due to the conversion of a γ-ray of definite frequency in the K and L levels of the atom will differ in energy by the difference in energy between the K and L absorption energies. Both in testing this equation, and in using it to deduce frequencies of the γ-rays, it is necessary to compare energies of β-rays determined in terms of a magnetic field, with absorption energies deduced from wave-length measurements of X-rays. It is thus important to obtain values of the absolute β-ray energies as accurate as possible. The most accurate previous values were those of Rutherford and Robinson.

scholarly journals The nature of the interaction between gamma-radiation and the atomic nucleus

1932 ◽  
Vol 136 (830) ◽  
pp. 662-691 ◽  
Keyword(s):  
Angular Distribution ◽  
Atomic Nucleus ◽  
Atomic Number ◽  
Wave Length ◽  
Electronic Systems ◽  
Angular Range ◽  
Light Elements ◽  
Absorbed Energy ◽  
Additional Absorption ◽  
Γ Rays

A number of independent investigations by Chao, Meitner and Hupfeld, and Tarrant, have shown that the absorption of strongly filtered thorium C" γ-rays, both in magnitude and in the manner of its variation with the atomic number of the absorbing element, was in definite disaccord with what was independently known concerning the absorption of γ-rays by extra-nuclear electronic systems. The additional absorption was attributed to interaction with the nuclei of the atoms concerned. In the case of quantum energies as high as 2½ million electron-volts, interaction with a heavy nucleus is quite important. In lead, for example, it accounts for 20 per cent. of the total absorbing power of the atom. The amount of energy absorbed by a nucleus is roughly proportional to the square of its atomic number, and from the investigations of Jacobson and Tarrant, it appears that the absorption increases regularly from element to element. The object of the present investigation was to discover something of the nature of this interaction between the quantum and the nucleus. It was evident that the whole of the absorbed energy was not re-radiated without change of wave-length, since no certain difference was observed between the intensity of the secondary radiations from heavy and light elements within the angular range 10° to 30°, although the conditions were such that if a third of the energy absorbed by the nucleus had been re-radiated with uniform angular distribution and without change of wave-length it could have been detected with certainty.

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