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.

scholarly journals The photoelectric absorption of γ-rays in heavy elements

1935 ◽  
Vol 149 (866) ◽  
pp. 131-151 ◽  
Keyword(s):  
Absorption Coefficient ◽  
Incident Light ◽  
Heavy Particle ◽  
Photoelectric Effect ◽  
Heavy Elements ◽  
Simplified Model ◽  
Total Absorption ◽  
Photoelectric Absorption ◽  
Γ Rays ◽  
Atomic Electrons

The photoelectric effect in hydrogen-like atoms has been treated by various authors, and the object of this paper is to co-ordinate the various results and to obtain values of σ, the absorption coefficient, which should be valid for all ranges of hv 0 , the energy of a quantum of the incident light, and for all values of Z, the atomic number of the atom. To this end we shall develop a method which is applicable in the range not previously examined—where Z is large and hv 0 ~ mc 2 , m being the mass of the electron and c the velocity of light. The problem may be stated briefly as follows. The nucleus of the atom is a heavy particle and may therefore be regarded as fixed at the origin of co-ordinates. We shall neglect exchange interaction between the atomic electrons, assuming that each K-electron may be treated separately. We may then consider the absorption by a simplified model consisting of a fixed nucleus and one K-electron, so that the results obtained have to be doubled to give the total absorption by the K-shell. The system is then perturbed by a beam of γ-rays travelling along the Z-axis, the perturbing potentials being given by A y = b 0 [ e 2π iv 0 ( t - z/c ) + e -2π iv 0 ( t - z/c ) ], A x = A z = 0, A 0 = 0.

scholarly journals Gravitational Collapse versus Thermonuclear Explosion of Degenerate Stellar Cores

1994 ◽  
Vol 147 ◽  
pp. 186-213
Author(s):  
J. Isern ◽  
R. Canal
Keyword(s):  
Neutron Star ◽  
White Dwarfs ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Radioactive Elements ◽  
Border Line ◽  
Thermonuclear Explosion ◽  
Type Ia ◽  
Γ Rays ◽  
Ia Supernovae

AbstractIn this paper we review the behavior of growing stellar degenerate cores. It is shown that ONeMg white dwarfs and cold CO white dwarfs can collapse to form a neutron star. This collapse is completely silent since the total amount of radioactive elements that are expelled is very small and a burst of γ-rays is never produced. In the case of an explosion (always carbonoxygen cores), the outcome fits quite well the observed properties of Type Ia supernovae. Nevertheless, the light curves and the velocities measured at maximum are very homogeneous and the diversity introduced by igniting at different densities is not enough to account for the most extreme cases observed. It is also shown that a promising way out of this problem could be the He-induced detonation of white dwarfs with different masses. Finally, we outline that the location of the border line which separetes explosion from collapse strongly depends on the input physics adopted.

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 Some experiments on the production of positive electrons

1934 ◽  
Vol 144 (851) ◽  
pp. 235-249 ◽  
Keyword(s):  
Direct Information ◽  
Controlled Conditions ◽  
Γ Rays ◽  
Α Particles

This paper describes work curried out during the last year on the production of positive electrons, or positrons. by various radiations. Although it is probable that the positrons found in conjunction with cosmic raw have their origin in the interaction of some penetrating radiation with matter, these experiments gave no direct information about their mode of origin. In order to throw light on this and to have a method of studying their properties more closely it was necessary to seek a means of producing positrons under easily controlled conditions. Our first experiments directed to this end were those which showed that the radiation from beryllium bombarded by polonium α-particles, a radiation consisting of γ-rays and neutrons, could eject positrons from lead. A preliminary notice of these results was given by us in a letter to ‘Nature.’ Almost at the same time Meitner and Philipp and Curie anti Joliot reported the same effect.

DISCOVERY OF STRONGLY ENHANCED LOW ENERGY ALPHA DECAY OF A LONG-LIVED ISOMERIC STATE OBTAINED IN 16O + 197Au REACTION AT 80 MeV, PROBABLY TO SUPERDEFORMED BAND

1996 ◽  
Vol 11 (11) ◽  
pp. 861-869 ◽  
Author(s):  
A. MARINOV ◽  
S. GELBERG ◽  
D. KOLB
Keyword(s):  
Isomeric State ◽  
Alpha Decay ◽  
Low Energy ◽  
X Rays ◽  
Superdeformed Band ◽  
Calculated Probability ◽  
Γ Rays ◽  
Bombarding Energy ◽  
Α Particles ◽  
Superdeformed Nucleus

The reaction 16 O + 197 Au has been studied at a bombarding energy of 80 MeV. A group of 5.20 MeV α particles with a half-life of about 90 m has been found in coincidence with characteristic X-rays of At and with γ-rays. The γ-ray energies fit predicted energies for superdeformed band. The data are interpreted as due to formation of a long-lived isomeric state which decays by low energy α-particles to SD band. The calculated probability for decay via a barrier of a superdeformed nucleus was found to be consistent with the experimental results.

Bahan Sasaran Sebagai Sumber Neutron yang Optimal untuk Boron Neutron Capture Therapy (BNCT)

2017 ◽  
Vol 1 ◽  
pp. 104
Author(s):  
Yan Surono ◽  
C Cari ◽  
Yohannes Sarjono
Keyword(s):  
Cancer Cells ◽  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Neutron Capture Therapy ◽  
Radioactive Elements ◽  
Therapeutic Technique ◽  
The Core ◽  
Boron Neutron Capture ◽  
Deadly Disease ◽  
Α Particles

<p><strong>Abstract</strong> Cancer is a deadly disease that exist on planet earth. Efforts were made to be able to kill cancer cells either by manual operation or by radiotherapy. One way to use energy radiation radioactive elements as killers of cancer cells is Boron Neutron Capture Therapy (BNCT). BNCT is a therapeutic technique that utilizes the interaction of neutron capture by the core 10B will produce α-particles and nuclei 7Li results by reaction 10B (n, α) 7Li. It therefore requires a material that will produce neutrons used in BNCT. Materials  target that will be searched in order to obtain optimal materials according to the requirements provided by the International Atomic Agency (IAEA).<em></em></p><p><em> </em></p><p><strong>Keywords </strong>: Kanker, Material, Neutron, BNCT</p><p align="center"><strong><em> </em></strong></p><p><strong>Abstrak</strong> Kanker adalah salah satu penyakit yang mematikan yang ada di planet bumi. Upaya upaya dilakukan untuk dapat membunuh sel kanker baik itu  secara operasi manual maupun dengan cara radioterapi. Salah satu cara yang memanfaatkan energi radiasi unsur unsur radioaktif sebagai pembunuh sel kanker adalah Boron Neutron Capture Therapy (BNCT). BNCT merupakan teknik terapi yang memanfaatkan interaksi tangkapan neutron oleh inti 10B yang akan menghasilkan partikel-α dan inti hasil 7Li melalui reaksi 10B(n,α) 7Li. Oleh sebab itu diperlukan material yang akan menghasilkan neutron digunakan dalam BNCT. Bahan - bahan sasaran yang akan ditelusur dalam upaya mendapatkan bahan yang optimal sesuai persyaratan yang diberikan oleh International Atomic Agency (IAEA).</p><p><em> </em></p><p><strong>Kata Kunci </strong>: Kanker, Material, Neutron, BNCT</p>

scholarly journals Chromosome Damage in Human Cells by γ Rays, α Particles and Heavy Ions: Track Interactions in Basic Dose-Response Relationships

2012 ◽  
Vol 179 (1) ◽  
pp. 9 ◽  
Author(s):  
Bradford D. Loucas ◽  
Marco Durante ◽  
Susan M. Bailey ◽  
Michael N. Cornforth
Keyword(s):  
Dose Response ◽  
Heavy Ions ◽  
Human Cells ◽  
Chromosome Damage ◽  
Γ Rays ◽  
Α Particles
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