The γ-rays of radium (B + C) and of thorium (C + C')

Reliable information about the γ-rays emitted by radium C' is particularly valuable since the main features of the nuclear level system are shown by the groups of long range α-particles and are hence accessible to direct investigation. These long range groups of α-particles have been measured recently by Rutherford, Lewis and Bowden by a greatly improved method which has not only brought to light several new groups, but in addition has given considerably greater accuracy in the determination of the energies of the groups than had been possible in the past. The energy of these groups in excess of that of the normal group is a measure of the excitation energy of the nucleus and the older measurements had indicated, as was to be expected, a close correspondence between these energies and the quantum energies of the γ-rays. The recent more accurate measurements of Rutherford, Lewis and Bowden provided the opportunity of a more rigorous test of this connection and showed the possibility, by the combination of the information from these two sources, of a direct experimental determination of the level system. However, the accuracy of the published data on the Ra C γ-rays deduced from the natural β-ray spectrum was subject to some doubts for the following reasons. The measurements dated from 1924 when the absolute energies of certain strong groups in the β-ray spectrum were measured and the energies of the remaining lines determined by relative measurements. The strong groups in question lay between 0.4 X 10 5 and 3.0 X 10 5 volts and the procedure of step-wise comparision up to energies of over 2 X 10 6 volts may have led to cumulative errors. More serious was that recent measurements on the Th (B + C) β-ray spectrum had thrown doubt on the correctness of the absolute values. Lastly, experiment gives values for H ρ , that is the momenta of the electrons in the groups, and the calculation of the energies involves e / m . The older data had been based on e / m = 1.769 X 10 7 , and while the change to the value 1.760 X 10 7 alters the energies proportionally far less, there was involved here an avoidable error which had to be removed.

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The thermal conductivity of some gases at 0° C

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1934.0064 ◽

1934 ◽

Vol 144 (853) ◽

pp. 496-513 ◽

Cited By ~ 50

Keyword(s):

Carbon Dioxide ◽

Thermal Conductivity ◽

Kinetic Theory ◽

Molecular Changes ◽

The Past ◽

Comprehensive Account ◽

The Absolute ◽

Relative Measurements ◽

Gas Conduction ◽

Heat Transfers

During recent years an increased interest has been displayed in the phenomena of gas conduction, particularly in their application to the observation of molecular changes and chemical dissociations. While relative measurements usually suffice for these purpose, there have also been carefully planned researches on the absolute thermal conductivities of gases, the results of which are of value in the development of the kinetic theory. A comprehensive account of the methods which have been employed in the past for the measurement of the thermal conductivity of gases is given in a recent paper by Trautz and Zündel, who include also a table of the available data to 1931 for air, hydrogen, and carbon dioxide. The lack of agreement between the values obtained by different workers shown in this table can be explained by the smallness of the quantity measured, and by the difficulty of eliminating the heat transfers by convection and by radiation, one or both of which are always present.

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Culturomics meets random fractal theory: insights into long-range correlations of social and natural phenomena over the past two centuries

Journal of The Royal Society Interface ◽

10.1098/rsif.2011.0846 ◽

2012 ◽

Vol 9 (73) ◽

pp. 1956-1964 ◽

Cited By ~ 74

Author(s):

Jianbo Gao ◽

Jing Hu ◽

Xiang Mao ◽

Matjaž Perc

Keyword(s):

Long Range ◽

Driving Forces ◽

Fractal Theory ◽

Natural Phenomena ◽

Social Phenomena ◽

Long Range Correlations ◽

The Past ◽

Random Fractal ◽

Data Collection And Analysis

Culturomics was recently introduced as the application of high-throughput data collection and analysis to the study of human culture. Here, we make use of these data by investigating fluctuations in yearly usage frequencies of specific words that describe social and natural phenomena, as derived from books that were published over the course of the past two centuries. We show that the determination of the Hurst parameter by means of fractal analysis provides fundamental insights into the nature of long-range correlations contained in the culturomic trajectories, and by doing so offers new interpretations as to what might be the main driving forces behind the examined phenomena. Quite remarkably, we find that social and natural phenomena are governed by fundamentally different processes. While natural phenomena have properties that are typical for processes with persistent long-range correlations, social phenomena are better described as non-stationary, on–off intermittent or Lévy walk processes.

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The ranges of the α-particles from the radioactive emanations and “A” products and from polonium

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1932.0086 ◽

1932 ◽

Vol 136 (829) ◽

pp. 349-363 ◽

Cited By ~ 20

Keyword(s):

Long Range ◽

Point Of View ◽

Counting Methods ◽

Γ Rays ◽

The Mean ◽

High Degree ◽

Α Particles

The analysis of groups of α-particles by new counting methods has been described in previous papers, in which details have been given of the examination of the α-particles emitted by radium-C and -C' thorium-C and -C', and actinium-C and -C', including the long range particles. The methods have the advantage that any appreciable inhomogeneity of a group of α-particles is readily detected, and moreover, the mean range of a group may be directly measured with a high degree of precision. The experiments have now been extended to an examination of the α-particles emitted by the emanations and “A” products of the three radioactive series, and by polonium. The examination of these α-ray groups is not only of great interest from the point of view of the radioactive transformations, but also for the possible connection with the emission of γ-rays.

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The association of γ-rays with the α-particle groups of thorium C

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1932.0089 ◽

1932 ◽

Vol 136 (829) ◽

pp. 396-406 ◽

Cited By ~ 5

Keyword(s):

Long Range ◽

Direct Evidence ◽

Transition Probabilities ◽

Essential Difference ◽

Γ Radiation ◽

Γ Rays ◽

The One ◽

Alternative Processes ◽

Particle Group ◽

Α Particles

As a result of the experiments of Rutherford, Ward and Lewis, it is now generally accepted that the emission of γ-rays from radioactive bodies is associated with the transitions of α-particles between stationary states in the nucleus. Direct evidence for the existence of these excited states in the case of radium C' is obtained from the several groups of long range α-particles which have been detected. Rosenblum has found that thorium C also emits several groups of α-particles, and the existence of a corresponding number of nuclear α-particle states can be safely inferred, which should also give rise to γ-radiation. This case was first discussed by Gamow, who pointed out that there was an essential difference here from radium C' In the latter body the extra α-particle states all have energy greater than the normal, and emission of the corresponding long range α-particles is a rare phenomenon, of the order of one long range particle for a million normal α-particles. The case of radium C' appears to be accounted for satisfactorily by the assumption of two alternative processes, either internal nuclear switch or α-emission from the excited state, the relative frequencies of occurrence depending on the ratio of the transition probabilities. With thorium C, however, the most intense α-particle group is not the one of lowest energy, and the groups only vary in intensity by a factor of one hundred instead of one million as with radium C' The assumption of alternative processes of γ-and α-emission would lead to values for the ratio of the transition probabilities for the two processes which are absolutely incompatible with what is known about the orders of magnitude of the probabilities of α-particle emission and radiation switch. Gamow therefore proposed that the thorium C nucleus is initially formed with its α-particles all in the gromid state and that disintegration could sometimes occur in such a way as to leave the product nucleus excited. Rosenblum gives the following data for the velocities and relative intensities of the groups from thorium C.

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THE γ-RAYS OF THORIUM CC′

Canadian Journal of Research ◽

10.1139/cjr48a-028 ◽

1948 ◽

Vol 26a (5) ◽

pp. 313-325 ◽

Cited By ~ 3

Author(s):

S. C. Fultz ◽

G. N. Harding

Keyword(s):

Energy Level ◽

Long Range ◽

Level Scheme ◽

Electric Quadrupole ◽

Coincidence Rate ◽

A Value ◽

Γ Rays ◽

Γ Ray ◽

Particle Group ◽

Α Particles

At least two energy level schemes have been proposed for the ThC′ nucleus, which is excited in the β-disintegration ThCC′. That of Ellis (1933) includes three γ-rays of energies 0.726, 1.62, and 1.80 Mev., the 1.62 Mev. ray being doubtful. The level scheme of Latyschev and Kulchitsky (1940) has eight γ-rays including one of energy 2.2 Mev., for which no corresponding long-range α-particle group has been observed. The two level schemes lead to widely differing values for the total γ-ray energy of ThCC′. In the present investigation a value for the total γ-ray energy of ThCC′ has been obtained by measuring coincidences between the γ-rays of ThCC′ and the subsequently emitted α-particles of ThC′. It is shown that this value (0.14 Mev.) favors the level scheme of Ellis, including only the γ-rays of energy 0.726 and 1.80 Mev., and taking the former as electric quadrupole. It was found that under certain conditions the external bremsstrahlung excited by the β-rays of ThCC′ in the source-holder contributed appreciably to the coincidence rate. Precautions were taken to minimize this effect.

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DETERMINATION OF AN ABSOLUTE SCALE OF CAPACITANCE

Canadian Journal of Physics ◽

10.1139/p64-005 ◽

1964 ◽

Vol 42 (1) ◽

pp. 53-69 ◽

Cited By ~ 21

Author(s):

A. F. Dunn

Keyword(s):

Research Council ◽

National Research Council ◽

The Past ◽

Absolute Scale ◽

Measuring Techniques ◽

The Absolute ◽

Better Than

In the past decade or two, the measurement of capacitance has become of much greater importance in many fields of scientific and technological investigation as well as forming the basis of many production applications. The capabilities of the capacitance measuring techniques available are of great importance, and the measurement and maintenance of an absolute scale of capacitance has become of prime importance. In the National Research Council of Canada, the absolute unit of capacitance is now known with an accuracy better than ±0.0005%, with the capability of scaling the unit of capacitance over six decades of capacitance both above and below 1 pf (1 × 10−12 f) without introducing an additional indeterminacy any greater than ±0.0005% or ±0.3 af (af = attofarad = 10−18 f).

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Analysis of α-rays by an annular magnetic field

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1933.0043 ◽

1933 ◽

Vol 139 (839) ◽

pp. 617-637 ◽

Cited By ~ 38

Keyword(s):

Magnetic Field ◽

Long Range ◽

Resolving Power ◽

Counting Method ◽

Range Measurements ◽

Considerable Uncertainty ◽

Radioactive Substances ◽

Γ Rays ◽

The Mean ◽

Α Particles

In previous papers an account has been given of a new counting method for analysing the groups of α-rays emitted by radioactive substances, and for measuring directly their mean range in air. In the course of these experiments, we showed that the long range groups of α-particles from radium C' are very complex, consisting of at least nine groups, with mean ranges lying between 7·7 and 11·6 cm. of air. As it is believed that the energies of these long range groups are intimately connected with those of the γ-rays from radium C', it has become of great importance to determine the energies of these groups of particles with precision. As, however, the seven groups with ranges between 9·5 and 11·6 cm. differ so little in velocity that they can only be partially resolved in range measurements, it was very difficult in our experiments to determine the mean ranges with accuracy. Moreover, there has been considerable uncertainty as to the precise relation between the range and velocity of such long range particles. A much greater resolving power can be obtained by a direct velocity determination, using a magnet to bend the α-rays into a circle. The great Paris electromagnet has been used in this way by Rosenblum, who photographed the α-ray spectra produced by the well-known focussing method. He has demonstrated the complexity of a number of α-ray groups, and has measured their velocities with an accuracy of at least 1 in 1000.

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The relative intensities of the groups in the magnetic β-ray spectra of radium B and radium C

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1927.0041 ◽

1927 ◽

Vol 114 (767) ◽

pp. 276-288 ◽

Cited By ~ 4

Keyword(s):

The Body ◽

Unique Determination ◽

Level System ◽

Intensity Measurements ◽

Accuracy Of Measurements ◽

Important Addition ◽

Γ Rays ◽

The Subject ◽

The Individual

It is well known that the study of the energy of the groups of homogeneous β-particles emitted by radio-active bodies has led to many important results, of these the chief is that these groups are due to the conversion of the characteristic γ-rays emitted by the body during the disintegration. From the measurement of the energy of these groups, it has been possible to deduce the energy or frequency of the γ-rays, and there appears to be evidence indicating that the γ-rays are associated with a nuclear level system in the manner familiar from X-ray and optical spectra. This opens up a promising field of work, since a knowledge of these level systems, and the way they varied from body to body would be an important addition to our all too scanty knowledge of the nucleus. Unfortunately, it must be admitted that the existing measurements of the β-ray groups are not of sufficient accuracy to provide a unique determination of the level system, they indicate strongly that the level systems exist, but it is difficult to deduce the actual arrangement with any certainty. An increase in the accuracy of the β-ray measurement would undoubtedly lead to interesting conclusions, but no simple way has as yet been proposed by which this can be achieved. Instead of attempting this method we have attacked the β- and γ-ray problem from another side. Previous investigations have been concerned chiefly with the energy of the individual electrons comprising the β-ray groups and of the γ-rays which can be deduced from them, but it is clear that any theory of their role in the disintegration must also take into consideration their intensities. This seems to be a more promising method of advance than that of trying to increase the accuracy of measurements already carried to a fraction of a per cent., since even approximate values of the intensities would be valuable. There are three main lines along which intensity measurements can usefully be made, one of which is the subject of the present paper. Considered by itself, each is interesting, but since it appears likely that the most valuable results will be obtained by comparing all three, it is permissible to refer briefly to them here.

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Analysis of the α-particles emitted from thorium C and actinium C

Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character ◽

10.1098/rspa.1931.0155 ◽

1931 ◽

Vol 133 (822) ◽

pp. 351-366 ◽

Cited By ~ 18

Keyword(s):

Long Range ◽

Special Interest ◽

Differential Method ◽

Automatic Method ◽

Excited Nucleus ◽

Γ Rays ◽

Α Particles ◽

Corresponding Analysis

In a recent paper, an account has been given of the analysis of the long range α-particles emitted by radium C. Nine distinct groups of α-particles were detected varying in range between 7·8 and 11·6 cm. in air. Evidence was given that the emission of γ-rays from radium C is intimately connected with the occurrence of these groups of long range α-particles, and it was concluded that the γ-rays arise from the transition of an α-particle in an excited nucleus between two levels of different energies. This question has been discussed in more detail by Rutherford and Ellis, who have advanced a tentative theory to account for the relation between the energies of the γ-rays emitted from radium C. In the present paper we give the results of a corresponding analysis of the long range α-particles from thorium C and an analysis of the groups of α-particles emitted from actinium C. In these experiments the differential method of analysis was used, as in the experiments with radium C. In the present experiments, however, instead of recording the α-particles photographically on a moving film, we have mainly employed the automatic method of counting, using thyratrons in place of the oscillograph. This method, which has been developed by one of us (C. E. Wynn-Williams), has been fully discussed in a recent paper. Here it suffices merely to refer to one or two points of special interest in connection with the present research.

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