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

1931 ◽  
Vol 133 (822) ◽  
pp. 351-366 ◽  
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.

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

1934 ◽  
Vol 143 (849) ◽  
pp. 350-357 ◽  
Keyword(s):  
Long Range ◽  
Published Data ◽  
Level System ◽  
The Past ◽  
Rigorous Test ◽  
Γ Rays ◽  
The Absolute ◽  
Relative Measurements ◽  
Α Particles

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.

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

1932 ◽  
Vol 136 (829) ◽  
pp. 349-363 ◽  
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.

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

1932 ◽  
Vol 136 (829) ◽  
pp. 396-406 ◽  
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.

THE γ-RAYS OF THORIUM CC′

1948 ◽  
Vol 26a (5) ◽  
pp. 313-325 ◽  
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.

scholarly journals Analysis of the long range α-particles from radium C' by the magnetic focussing method

1933 ◽  
Vol 142 (846) ◽  
pp. 347-361 ◽  
Keyword(s):  
Long Range ◽  
Energy Levels ◽  
Resolving Power ◽  
Complete Analysis ◽  
Direct Information ◽  
Annular Ring ◽  
Excited Nucleus ◽  
Counting Methods ◽  
Ring Magnet ◽  
Α Particles

In our last paper we gave an account of an annular ring magnet capable of focussing groups of α -particles after they have traversed a semicircle of 40 cm. radius. By this method the velocities of a number of important groups of α -particles were measured with a relative accuracy, it is believed, of 1 in 5000. Preliminary measurements were described of the two long range groups from thorium C´ and of two from radium C´. In a previous paper we had shown by means of counting methods that the long range groups of α -particles from radium C´ were much more complicated than those from thorium C´, and consisted of at least nine distinct groups. This older method, however, had not sufficient resolving power to separate completely a number of these groups, and the annular ring magnet was constructed primarily to make a more complete analysis of this α -ray spectrum. It is hardly necessary at this stage to emphasize the importance of accurate measurements of the energies of these groups, for they give us direct information of the energy levels of the α -particle in an excited nucleus, which is of fundamental importance in considering the question of the origin of the γ -rays from radium C´.

scholarly journals Analysis of α-rays by an annular magnetic field

1933 ◽  
Vol 139 (839) ◽  
pp. 617-637 ◽  
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.

scholarly journals Evaluation the Safety and Security Procedures used In X-ray Clinics in Al-Harthiya-Baghdad

2021 ◽  
Vol 2114 (1) ◽  
pp. 012009
Author(s):  
Thuraya A. Abdul Hussian ◽  
Anwar kh. Farman
Keyword(s):  
Ionizing Radiation ◽  
X Rays ◽  
X Ray ◽  
Beta Particles ◽  
Medical Clinics ◽  
Γ Rays ◽  
Health Laws ◽  
Different Sources ◽  
Α Particles ◽  
Security Procedures

Abstract Radiation is a form of energy, its emitted either in the form of particles such as α-particles and β-particles (beta particles including the electron and the positron) or waves such as sunlight, X-rays and γ-rays. Radiation found everywhere around us and it comes from many different sources naturally or man-made sources. In this study a questionnaire was distributed to people working in the field of X-rays that used for a medical imaging (X-ray and CT-scan) to evaluate the extent of awareness and knowledge in estimate the damage of ionizing radiation as a result of wrong use. The questionnaire was distributed to medical clinics in Al-Harithiya in Baghdad, which it’s considered as one of the important areas in Iraq to attract and treat patients. It’s found that most of the commitment of radiography clinics by safety and security procedures. Most of the radiology clinics abide by most of the Iraqi Ministry of Health laws. However, some clinics did not implement some of the security and safety conditions

scholarly journals The nuclear photoelectric effect

1935 ◽  
Vol 151 (873) ◽  
pp. 479-493 ◽  
Author(s):  
James Chadwick ◽  
M. Goldhaber
Keyword(s):  
Heavy Particle ◽  
Photoelectric Effect ◽  
Necessary Condition ◽  
Mass Defect ◽  
Radioactive Elements ◽  
Negative Mass ◽  
Photo Effect ◽  
Sufficient Intensity ◽  
Γ Rays ◽  
Α Particles

Some time ago we reported in ‘Nature’ the observation of a nuclear photo-effect, the disintegration of the deutron by γ-rays. An effect of y-rays upon complex nuclei might be expected to occur from analogy with the phenomena of excitation and ionization of atoms by light, and such an effect has been looked for from time to time by various investigators. A necessary condition to make disintegration possible is that the energy of the γ-ray quantum must be greater than the binding energy of the particle which is to be removed from the nucleus. The most energetic γ-rays which are readily available in sufficient intensity are those of thorium C", which have an energy hv — 2·62 x 10 6 electron volts. One can hope, therefore, using these γ-rays, to produce disintegration with the emission of a heavy particle, such as a neutron, proton, etc., only in those nuclei which have a small or negative mass defect, such as the nuclei of deuterium, beryllium, and those radioactive elements which emit α-particles. In fact, only the nuclei of deuterium and beryllium have so far been disintegrated in this way. The disintegration of beryllium by the γ-rays of radium was first reported by Szilard and Chalmers. No evidence of a photo-electric disintegration amongst the radioactive elements has yet been found.

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