THE ABSORPTION OF GAMMA-RAYS FROM Co60

1947 ◽  
Vol 25a (6) ◽  
pp. 303-314 ◽  
Author(s):  
W. V. Mayneord ◽  
A. J. Cipriani
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Gamma Rays ◽  
Heavy Elements ◽  
Photoelectric Absorption ◽  
Lead Absorber ◽  
Absorption Coefficients ◽  
Cobalt Radiation ◽  
Good Agreement ◽  
Made In

Measurements of the absorption of gamma-rays from Co60 and radium have been made in a number of materials. Variation of absorption coefficient of the gamma-rays from radium with thickness of lead absorber is in agreement with recent experimental determinations. The gamma-rays from Co60 are approximately monochromatic and are therefore suitable for testing theoretical absorption formulae. The absorption coefficient per electron for materials of atomic number equal to or less than that of aluminium was in agreement with the Klein–Nishina formula, assuming the cobalt radiation to consist of two lines at 1.10 and 1.30 Mev. respectively. The photoelectric absorption coefficients per electron for heavy elements are in good agreement with the theory developed by Hulme, McDougall, Buckingham, and Fowler. This coefficient varies approximately as Z3.5.

scholarly journals The absorption of monochromatic X-ray beams, of wave-length in the region 50 to 20 X -units, in lead, tin, copper, and iron

1935 ◽  
Vol 152 (876) ◽  
pp. 402-417 ◽  
Author(s):  
John Read ◽  
John Cunningham McLennan
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Wave Length ◽  
Detailed Account ◽  
Photoelectric Absorption ◽  
Absorption Coefficients ◽  
X Ray ◽  
Method Of Measurement ◽  
Absorption Measurements

In a previous paper an account has been given of the measurement of the absorption of monochromatic X-ray beams of wave-length in the region 50 to 20 x -units, in carbon and aluminium. The relation of the measured coefficient of absorption to the wave-Iength did not differ from that predicted by the Klein-Nishina formula by more than 1%. The method used in that experiment has been improved, and used to measure the absorption coefficients of lead, tin, copper, and iron for similar monochromatic beams. Because lead has been used very extensively for absorption measurements the primary aim has been to measure as accurately as possible the dependence of its absorption coefficient on the wave-length of the radiation. It has not been possible to make such accurate measurements on tin, copper, and iron, but enough data has been obtained to determine the variation of the photoelectric absorption coefficient per electron with the atomic number of the absorbing element, with fair accuracy, for radiation in this region of wave-lengths. Since these absorption coefficients may find considerable application, it is considered well to give a more detailed account of the method of measurement, so that an independent judgment of their reliability may be made.

The Photoelectric Absorption of Gamma Rays

1931 ◽  
Vol 27 (1) ◽  
pp. 103-112 ◽  
Author(s):  
L. H. Gray
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Gamma Rays ◽  
Wave Length ◽  
X Rays ◽  
Photoelectric Absorption ◽  
Empirical Law ◽  
Γ Rays ◽  
Image Position

No satisfactory formula has so far been derived theoretically for the photoelectric absorption of X-rays and γ-rays. The empirical lawhas hitherto been generally accepted as giving approximately the variation of the photoelectric absorption coefficient per electron, with atomic numberZand wave length λ for X-rays of wave length greater than 100 X.U., and the validity of this law has often been assumed for γ-rays also.

THEORY OF THE PRESSURE-INDUCED ROTATIONAL SPECTRUM OF HYDROGEN

1959 ◽  
Vol 37 (10) ◽  
pp. 1187-1198 ◽  
Author(s):  
J. Van Kranendonk ◽  
Z. J. Kiss
Keyword(s):  
Experimental Data ◽  
Distribution Function ◽  
Absorption Coefficient ◽  
Pair Distribution Function ◽  
Wave Functions ◽  
Rotational Line ◽  
Induction Effect ◽  
Rotational Spectrum ◽  
Absorption Coefficients ◽  
Good Agreement

The theory of induced infrared absorption developed previously is applied to the pressure-induced rotational spectrum of hydrogen. The intensity of the rotational band is due mainly to the quadrupolar induction effect, and to a small interference effect between the quadrupolar and overlap moments. From the experimental data on the binary absorption coefficients, values of the angle-dependent overlap moments are obtained for H2–He, H2–H2, H2–Ne, H2–N2, and H2–A. A calculation of the overlap moment for pure H2 is presented. Rosen-type wave functions appear to be inadequate for a calculation of the small angle-dependent rotational as well as vibrational overlap moments. The temperature dependence of the binary absorption coefficient is calculated, taking into account the quantum effects in the pair distribution function, and found to be in good agreement with the experimental data. The dependence on the ortho–para ratio is also discussed. The double rotational line S(1) + S(1) has been observed and its intensity measured.

Sound absorption of textile curtains – theoretical models and validations by experiments and simulations

2016 ◽  
Vol 88 (1) ◽  
pp. 36-48 ◽  
Author(s):  
Reto Pieren ◽  
Beat Schäffer ◽  
Stefan Schoenwald ◽  
Kurt Eggenschwiler
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Planning Process ◽  
Measurement Data ◽  
Theoretical Models ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Semi Empirical ◽  
Field Sound ◽  
Good Agreement

Textile curtains can be designed to be good sound absorbers. Their acoustical performance, as usually described by the sound absorption coefficient, not only depends on the textile itself but also on the drapery fullness and the backing condition, that is, the spacing between the fabric and a rigid backing wall, or the absence of a backing in the case of a freely hanging curtain. This article reviews existing models to predict the diffuse-field sound absorption coefficient, which to date can only predict the case of flat curtains. A set of existing models is extended to the case of curtains with drapery fullness using a semi-empirical approach. The models consider different backing conditions, including freely hanging curtains. The existing and new models are validated by comparing predicted sound absorption coefficients with data measured in a reverberation room. Hereby, curtains consisting of different fabrics and with different degrees of fullness are considered. Besides situations with rigid backing, also the measurement data of textiles hung freely in space are included in this study. Comparisons reveal a very good agreement between measured and predicted sound absorption coefficients. Compared to currently available commercial sound absorption prediction software that can only handle the situation of flat textiles with rigid backing, the results of the presented models not only show a better agreement with measured data, but also cover a broader range of situations. The presented models are thus well applicable in the design and development of new textiles as well as in the room acoustical planning process.

Areas for Improvement in XRF Analysis of Low Atomic Number Elements

1992 ◽  
Vol 36 ◽  
pp. 73-80
Author(s):  
Bruno A.R. Vrebos ◽  
Gjalt T.J. Kuipéres
Keyword(s):  
Lower Limit ◽  
Atomic Number ◽  
Energy Dispersive Spectrometry ◽  
Limit Of Detection ◽  
Heavy Elements ◽  
Fluorescence Spectrometry ◽  
Accurate Analysis ◽  
X Ray ◽  
Made In

Accurate analysis of the light elements has been, from the early applications of X-ray fluorescence spectrometry a struggle compared to the determination of heavy elements in the same matrices. In contrast, there has been virtually no upper limit to the atomic number of the element that could be determined. The lower limit, however, has been continuously adjusted downward through the years. Clearly, the sensitivity as well as the lower limit of detection for the heavy elements have also been improved, but the effect is Jess striking than the advances made in the region of tight element performance. This paper deals specifically with wavelength dispersive sequential x-ray fluorescence spectrometry, although some of the observations made are equally applicable to energy dispersive spectrometry.

scholarly journals The absorption of hard monochromatic γ -radiation.—Part II

1932 ◽  
Vol 135 (826) ◽  
pp. 223-237 ◽  
Keyword(s):  
Atomic Number ◽  
Heavy Elements ◽  
Absorption Coefficients ◽  
Γ Radiation ◽  
Quantum Energy ◽  
High Quantum ◽  
Γ Ray ◽  
Very High ◽  
Considerable Intensity

Thorium C" emits in very considerable intensity a monochromatic γ-ray of very high quantum energy (2·649 × 10 6 e -volts) free from any other radiation of quantum energy greater than 0·786X 10 6 e -volts, so that it can be isolated by filtering through a few centimetres of lead. Experiments by Tarrant, Meitner and Hupfeld, Chao and by Jacobsen on the absorption of these rays are in agreement in leading to the conclusion that the scattering formula of Klein and Nishina is a good approximation for the elements of low atomic number. The absorption coefficients of the heavy elements, however, indicate that a new mode of γ-ray absorption is occurring, which may be nuclear in origin.

Deuteron bombardment of the heavy elements.

1940 ◽  
Vol 36 (4) ◽  
pp. 490-499 ◽  
Author(s):  
R. S. Krishnan ◽  
E. A. Nahum
Keyword(s):  
Atomic Number ◽  
Lead Isotope ◽  
Lead Isotopes ◽  
Absorption Measurement ◽  
Hard Work ◽  
Radioactive Isotopes ◽  
Heavy Elements ◽  
High Atomic Number ◽  
Deuteron Bombardment ◽  
Made In

The results of the bombardment of mercury, lead and thallium by 9 M.e.V. deuterons are reported. The following radioactive isotopes have been detected: 5·5 min., 48 min., 36 hr., 60 day mercury isotopes; 4·4 min., 10·5 hr., 44 hr., and 13 day thallium isotopes; 10·25 min., 2·75 hr., and 54 hr. lead isotopes; 18 hr. and 6·35 day bismuth isotopes. The 10·25 min. lead isotope is positron emitting, an interesting result in an element of high atomic number. Absorption measurement have been made of the radiations emitted by many of these isotopes and assignments have been made in most cases.In conclusion we wish to thank Dr N. Feather for valuable discussions, and also for making for us a Ra E source. We are indebted to Dr Lewis for advice in setting up the thyratron scale of eight counter. This paper would be incomplete without a sincere acknowledgement of our indebtedness to the hard work of past members of this laboratory who have been mainly responsible for setting up the cyclotron.One of us (R. S. K.) is grateful to the Royal Commissioners for the Exhibition of 1851 for the grant of an overseas scholarship which made this work possible.

ABSORPTION CORRECTIONS FOR RADIUM STANDARDIZATION

1951 ◽  
Vol 29 (4) ◽  
pp. 301-309 ◽  
Author(s):  
G. M. Keyser
Keyword(s):  
Absorption Coefficient ◽  
Atomic Number ◽  
Electronic Absorption ◽  
Empirical Formula ◽  
Measuring Equipment ◽  
Absorption Coefficients ◽  
Minimum Error ◽  
A Value

The absorption corrections necessary for radium standardization have been redetermined. The measuring equipment and technique have been investigated to find the conditions necessary for minimum error. A lead filtered, aluminum walled chamber was found to have the best characteristics. The electronic absorption coefficients measured with this chamber fit an empirical formula depending only on the atomic number. This formula gives a value for the absorption coefficient of radium salts which was compared with a direct experimental value.

Détermination du coefficient d'absorption des rayons X à partir des mesures de réflectométrie X

2004 ◽  
Vol 82 (1) ◽  
pp. 75-79 ◽  
Author(s):  
E Ech-chamikh ◽  
I Aboudihab ◽  
M Azizan ◽  
A Essafti ◽  
Y Ijdiyaou
Keyword(s):  
Absorption Coefficient ◽  
Amorphous Carbon ◽  
X Rays ◽  
Absorption Coefficients ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Simple Method ◽  
Material Layer ◽  
Reflectivity Spectra ◽  
Good Agreement

In this paper, we present a simple method that allows, among other things, to determine the absorption coefficient of X-rays from reflectivity measurements. This method is applicable if the analysed material is deposited on a substrate denser than the material layer, so that the X-rays reflectivity spectra exhibit two well-resolved descents. In such cases, the amplitude of the first descent (characteristic of the material layer) is directly related to the linear absorption coefficient of the material constituting the layer. We have been able to clarify this relationship and apply it successfully for several cases of materials, especially amorphous carbon and silicon. Values of thus obtained mass absorption coefficients are in very good agreement with those tabulated in the literature.[Journal translation]

scholarly journals Absorption of radium (B+C) gamma-rays

1945 ◽  
Vol 183 (994) ◽  
pp. 338-355 ◽  
Keyword(s):  
Gamma Rays ◽  
Electron Pair ◽  
Gamma Ray ◽  
Wave Length ◽  
Photoelectric Effect ◽  
Pair Formation ◽  
Photoelectric Absorption ◽  
Absorption Coefficients ◽  
Length Range ◽  
Effective Wave

New measurements of the absorption of filtered gamma-rays from radium (B + C) in aluminium, carbon and lead have been made. A small condenser type of ionization chamber has been used, which overcomes many of the difficulties usually inherent in this kind of measurement. Detailed consideration has been given to the corrections which must be applied to ionization measurements before absorption coefficients can be calculated. From the most recent theories of absolution by scattering, photoelectric effect, and electron pair formation, total absorption coefficients for lead over the wave-length range concerned have been calculated. The problem of the effective wave-length of a filtered heterogeneous gamma-ray beam is discussed in some detail, and a proposed method of estimation put forward. Comparison of the calculations of µ / ρ with the experimental figures indicates that the photoelectric absorption rises more rapidly with increasing wave-length than is predicted by theory.

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