The Atomic Number of a Radioactive Element at the moment of emission of the γ-rays

1925 ◽  
Vol 22 (6) ◽  
pp. 844-848 ◽  
Author(s):  
C. D. Ellis ◽  
W. A. Wooster
Keyword(s):  
Atomic Number ◽  
Nuclear Charge ◽  
Radioactive Element ◽  
Direct Solution ◽  
Γ Rays ◽  
The Moment

It is well known that the β-ray type of disintegration is usually accompanied by the emission of γ-rays, and it is a matter of great importance to decide which of these two phenomena occurs first, that is, whether the γ-rays are emitted before the nucleus disintegrates or afterwards. It is not practicable to attempt a direct solution of this problem, but since the emission of the disintegration electron results in a change of the nuclear charge of + 1 it would be sufficient to determine the atomic number of the radioactive body at the moment of emission of the γ-rays. For instance, an atom of the β-ray body radium B has an atomic number 82, but after disintegration when it becomes radium C it has an atomic number 83, so that if the γ-rays were known to be emitted from a body of atomic number 82 it would mean that they were emitted before the disintegration, whereas if the atomic number 83 were found it would show that they were emitted afterwards.

The Natural X-ray Spectrum of Radium B

1925 ◽  
Vol 22 (6) ◽  
pp. 834-837 ◽  
Author(s):  
Ernest Rutherford ◽  
W. A. Wooster
Keyword(s):  
Atomic Number ◽  
Atomic Structure ◽  
External Source ◽  
Spontaneous Transformation ◽  
X Ray ◽  
Γ Ray ◽  
The Moment

It is now well known that radium B is an isotope of lead of atomic number 82 with a mass 214, and consequently, if the atoms of radium B are bombarded by an external source of electrons, the spectrum excited in it should be identical with that of lead atomic number 82. A very interesting question arises with regard to the L radiation emitted by a source of radium B during its spontaneous transformation. At the moment of the expulsion of the disintegration electron from radium B, the internal atomic structure of radium B corresponds to an element of number 82, but an instant later, when the electron has escaped from the nucleus, the charge on the latter is 83 and there must follow a reorganisation of the external electrons. Under these conditions, we cannot be certain whether the L spectrum of radium B should correspond to an element of number 82 or 83. Since the excitation of the L spectrum is for the most part due to the action of the rays from the nucleus, the spectrum should correspond to number 82 if the emission of the γ-ray precedes the escape of the disintegration electron and number 83 if it is subsequent to this process.

scholarly journals Secondary electronic emissions from metal foils and animal tissues

1930 ◽  
Vol 130 (812) ◽  
pp. 63-80 ◽  
Keyword(s):  
Relative Sensitivity ◽  
Theoretical Treatment ◽  
Secondary Effects ◽  
Animal Tissues ◽  
Metal Foils ◽  
Ionisation Chamber ◽  
Γ Rays ◽  
The Subject ◽  
The Moment ◽  
Living Tissues

The measurement of penetrating X-and γ-rays by means of an ionisation chamber has been the subject of a large number of experimental and theoretical investigation, but still presents interesting problems. The ionisation current observed in any given case depends (among other factors) upon the material of which the ionisation chamber is constructed, and entirely fallacious estimates of the relative intensities of beams X-and γ-rays of different wave-lengths may be obtained, unless the infulence of this factor be kept in mind. The experiments described below are concerned with the relative sensitivity of small ionisation chambers lined with various metal foils and animal tissues, when irradiated by beams of X-and γ-rays of different mean wave-lengths. Animal tissues were inclued among the materials of which chambers have been constructed, since the results of X-ray measurements with such chambers are of importance in the consideration of the question of relative sensitivity of living tissues to various penetrating radiations. The ionisation current observed in small closed ionisation chambers (volume 1 c. c. approximately) filled with air at atmospheric pressure is due to ionisation produced in the air itself by the primary radiation and also to secondary effects due to β-radiation produced in the walls of the chamber. The latter appears of relatively greater importance in small chambers, until with chambers of the order of size contemplated, the primary effect becomes negligible for walls composed of heavy elements, and the ionisation current is almost entirely determined by the secondary elecronic emission from the wall. In view of the complexity of the effects occuring in such a chamber we cannot hope at the moment to construct an adequate theoretical treatment, but many proceed to discuss the problem as below, in the hope of obtaining at least qualitative agreement with the observations.

Mössbauer Isomer Shifts and Hyperfine Splitting of the 145.4 keV γ-rays of 141Pr

1971 ◽  
Vol 26 (3) ◽  
pp. 357-367 ◽  
Author(s):  
W.H. Kapfhammer ◽  
W. Maurer ◽  
F.E. Wagner ◽  
P.E. Kienle
Keyword(s):  
Magnetic Moment ◽  
Charge Radius ◽  
Hyperfine Splitting ◽  
Nuclear Charge ◽  
Magnetic Hyperfine ◽  
Nuclear Charge Radius ◽  
Fluorine Compounds ◽  
Γ Rays

Abstract The Mössbauer scattering of the 145.4 keV γ-rays of 141Pr was observed in a number of praseodymium compounds. From the isomer shifts between trivalent and tetravalent fluorine compounds the value Δ/(r2) = + 12 · 10-3 fm2 was derived for the change of the nuclear charge radius. The magnetic moment of the 145.4 keV state, μ7/2= (2.8 ± 0.2) μN, was deduced from the magnetic hyperfine pattern observed with scatterers of antiferromagnetic PrO2 .

scholarly journals The internal conversion of γ-rays with the production of electrons and positrons

1935 ◽  
Vol 148 (865) ◽  
pp. 708-728 ◽  
Keyword(s):  
Atomic Number ◽  
Internal Conversion ◽  
Energy State ◽  
Structure Constant ◽  
Negative Energy ◽  
Fine Structure Constant ◽  
Radioactive Atom ◽  
Electrons And Positrons ◽  
Γ Rays ◽  
Γ Ray

A γ-ray emitted from the nucleus of a radioactive atom may be absorbed by one of the outer electrons, with the production of a β-ray. This process has already been treated at length and fairly satisfactory results have been obtained. If the energy of the γ-ray is greater than 2 mc 2 it is possible for the γ-ray to be absorbed by one of the electrons in a state of negative energy. This electron is then emitted eith an energy hν 0 - | E' |, where hν 0 is the energy of the γ-ray and E' the energy of the electron in the negative energy state. We are thus left with an electron of energy hν 0 - | E' |, and a hole, or positron, of energy | E' |. The problem has been treated by Oppenheimer and Plesset, who gave an approximate answer in the form I ~ α 3 Z 2 , where I is the Internal Conversion Coefficient, that is, the number of pairs created for each γ-ray emitted from the nucleus, α is the fine structure constant and Z the atomic number of the nucleus. The approximations used were very rough, and as the problem could be treated rigorously it was decided that an accurate computation would be worth attempting. While these calculations were in progress, Oppenheimer and Nedelski gave another calculation of I, in which they found that for high energies it was almost independent of the atomic number of the nucleus emitting the γ-ray. They therefore neglected completely the electrostatic field of the nucleus. According to these authors the method should be valid when Z c /137 ν ≪ 1

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.

Radioactive Pollution

2002 ◽  
Keyword(s):  
Atomic Number ◽  
Electromagnetic Waves ◽  
Neutron Radiation ◽  
Atomic Weight ◽  
Atomic Mass Unit ◽  
X Rays ◽  
Orbital Electron ◽  
Γ Rays ◽  
The Difference ◽  
A Charge

Radiation that, on passage through matter, produces ions by knocking electrons out of their orbits is called ionizing radiation. This radiation is produced through decomposition of unstable, naturally occurring or synthetic elements referred to as radionuclides. The four types of radiation are ∝-particles, β-particles, γ-rays, and neutrons. The ∝-particles have a mass of two protons and two neutrons and a charge of +2; β -particles are electrons with a mass of 0.00055 atomic mass unit (amu) and a charge of –1; γ -rays and X-rays are high-frequency electromagnetic waves with no mass and no charge. The difference between γ -rays and X-rays is that γ -rays occur naturally, whereas X-rays are generated. In addition, γ -rays are of higher frequency than X-rays. Release of an ∝ -particle leads to the formation of a daughter element with an atomic number 2 units lower and an atomic weight 4 units lower than that of the parent nuclide. Similarly, release of a β -particle from the nucleus causes conversion of a neutron to a proton, producing a daughter element with the same atomic weight as the parent nuclide but with its atomic number increased by 1 unit. Neutron radiation does not occur naturally and is released only from synthetic radionuclides. Neutrons, which have no charge, are formed from protons. This conversion is accompanied by the release of an orbital electron from the atom. Neutrons produce ions indirectly, by collisions with hydrogen atoms. The impact knocks out protons, which in turn produce ions on passage through matter. Capture of a neutron forms an isotope of the parent nuclide with its atomic weight increased by 1 unit. The mode of action of particles (∝ and β ) varies from that of photons (γ - and X-rays). When ∝- or β -particles travel through matter, their electric charges (positive or negative) cause ionization of the atoms in the matter. This is called a direct effect. Whereas the track of ∝- particles is short and straight, β -particles scatter, frequently producing a wavy track. Gamma- and X-rays act indirectly.

Muonic X rays and capture γ rays in 89Y

1970 ◽  
Vol 48 (24) ◽  
pp. 3029-3037 ◽  
Author(s):  
D. Kessler ◽  
R. J. McKee ◽  
C. K. Hargrove ◽  
E. P. Hincks ◽  
H. L. Anderson
Keyword(s):  
High Resolution ◽  
Dirac Equation ◽  
Charge Distribution ◽  
Nuclear Charge ◽  
Atomic Transition ◽  
X Rays ◽  
Transition Energies ◽  
Line Intensities ◽  
Cascade Calculation ◽  
Γ Rays

The main mu-atomic transition energies in 89Y were measured with a high-resolution Ge(Li) spectrometer. The nuclear charge parameters of yttrium were derived by fitting the observed transition energies to those obtained by numerically solving the Dirac equation, using a radially symmetric Fermi charge distribution. The line intensities were also measured and shown to agree reasonably well with the results of a cascade calculation. Finally, we measured the energies and intensities of the most prominent capture γ rays. Most of these γ rays could be assigned to known transitions in the strontium isotopes 86 through 89.

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