The National Physical Laboratory secondary standard therapy-level X-ray exposure meter

1972 ◽  
Vol 45 (538) ◽  
pp. 775-778 ◽  
Author(s):  
L. A. W. Kemp
Keyword(s):  
Standard Therapy ◽  
National Physical Laboratory ◽  
Secondary Standard ◽  
X Ray ◽  
Physical Laboratory

Address of the President, Professor P. M. S. Blackett, C.H., at the Anniversary Meeting, 30 November 1966

1967 ◽  
Vol 167 (1006) ◽  
Keyword(s):  
National Physical Laboratory ◽  
Simple Approach ◽  
Ionic Crystals ◽  
X Ray Diffraction ◽  
Complete Structure ◽  
Principal Role ◽  
X Ray ◽  
Physical Laboratory ◽  
Royal Institution

The Copley Medal is awarded to Sir Lawrence Bragg, O.B.E., M.C., F.R.S. Bragg’s career has precisely coincided with the growth of a major field of science—the X-ray diffraction analysis of crystal structures. This had its beginning in his own early researches, and he has throughout played a principal role by his leadership at a series of laboratories, at Manchester, at the National Physical Laboratory, at Cambridge and at the Royal Institution, and in many other ways. He was the first to determine the atomic arrangement in a crystal (sodium chloride), and this work marked the introduction of a technique which has since been successfully applied to increasingly complicated molecules, culminating in the complete structure determination of the protein lysozyme at the Royal Institution a year before his retirement. Bragg has been prominent in the development of methods, beginning with the Law named after him; he also pioneered or encouraged the application of these methods in several fields—ionic crystals, elementary oxides, silicates, metals and proteins. The striking characteristic of Bragg as a scientist has been his direct and simple approach to complicated physical situations; his solutions of problems have a lucidity and simplicity which, in retrospect, make one forget how baffling they often seemed in advance.

scholarly journals THE PERFORMANCE OF THE "NPL SECONDARY STANDARD, THERAPY LEVEL X-RAY EXPOSURE METER"

1978 ◽  
Vol 33 (6) ◽  
pp. 733-738
Author(s):  
SHINOBU ISHIYAMA ◽  
KIYOSHI TANAKA ◽  
SUSUMU MORIKAWA
Keyword(s):  
Standard Therapy ◽  
Secondary Standard ◽  
X Ray

Alloys Research Committee: The Work of the Alloys of Iron Research Committee

1934 ◽  
Vol 127 (1) ◽  
pp. 277-298 ◽  
Author(s):  
C. H. Desch
Keyword(s):  
National Physical Laboratory ◽  
Basic Material ◽  
High Melting Point ◽  
Research Committee ◽  
Laboratory Methods ◽  
Physical Methods ◽  
X Ray ◽  
Upper Limit ◽  
Physical Laboratory ◽  
Systematic Knowledge

The Alloys Research Committee of The Institution of Mechanical Engineers began its work in 1890, and from 1902 onwards the investigations were conducted in the National Physical Laboratory. The Eleventh Report, published in 1921, dealt very fully with the light alloys of aluminium. At that stage it was decided that further research should be devoted to the alloys of iron with the object of determining the fundamental nature of the alloys of iron with various metals and non-metals to serve as a basis for a more systematic knowledge of the steels used in practice. The investigation has comprised the construction of equilibrium diagrams using thermal, microscopical, X-ray, and other physical methods. Iron being more sensitive to the influence of minute quantities of impurities than most other metals, it was necessary to prepare very pure iron as the basic material. Since 1921, the alloys of iron with oxygen, phosphorus, silicon, chromium, and manganese have been studied. As all the alloys are of high melting point, many new laboratory methods have had to be developed, the technique of experiments at high temperatures becoming more difficult the higher the upper limit is raised. In the course of the research, therefore, it has been necessary to prepare new refractories and to design special forms of apparatus in order to avoid contamination. The paper contains a summary of the results obtained in the course of the work, and it is shown how these bear upon the improvement of steels for structural and engineering purposes. The investigation is being extended to other elements, and ultimately to the influence of more than one solid element when present simultaneously in the alloy.

Address of the President, Professor P. M. S. Blackett, C.H., at the Anniversary Meeting, 30 November 1966

1967 ◽  
Vol 296 (1444) ◽  
Keyword(s):  
National Physical Laboratory ◽  
Simple Approach ◽  
Ionic Crystals ◽  
X Ray Diffraction ◽  
Complete Structure ◽  
Principal Role ◽  
X Ray ◽  
Physical Laboratory ◽  
Royal Institution

The Copley Medal is awarded to Sir Lawrence Bragg, O. B. E., M. C., F. R. S. Bragg’s career has precisely coincided with the growth of a major field of science─the X-ray diffraction analysis of crystal structures. This had its beginning in his own early researches, and he has throughout played a principal role by his leadership at a series of laboratories, at Manchester, at the National Physical Laboratory, at Cambridge and at the Royal Institution, and in many other ways. He was the first to determine the atomic arrangement in a crystal (sodium chloride), and this work marked the introduction of a technique which has since been successfully applied to increasingly complicated molecules, culminating in the complete structure determination of the protein lysozyme at the Royal Institution a year before his retirement. Bragg has been prominent in the development of methods, beginning with the Law named after him; he also pioneered or encouraged the application of these methods in several fields—ionic crystals, elementary oxides, silicates, metals and proteins. The striking characteristic of Bragg as a scientist has been his direct and simple approach to complicated physical situations; his solutions of problems have a lucidity and simplicity which, in retrospect, make one forget how baffling they often seemed in advance.

scholarly journals The composition of the x-rays from various metals

1917 ◽  
Vol 93 (653) ◽  
pp. 427-442 ◽  
Keyword(s):  
National Physical Laboratory ◽  
Point Of View ◽  
X Rays ◽  
Crystal Spectrometer ◽  
Cavendish Laboratory ◽  
Precise Method ◽  
X Ray ◽  
Physical Laboratory ◽  
The Subject

In a paper published in the ‘Philosophical Transactions’ in 1908, the writer described some experiments on the X-rays emitted by a variety of metals when used as anticathodes in an X-ray bulb. Among the results established was the homogeneity of a large proportion of the X-rays when the bulb was very “soft.” The absorption curves of the several homogeneous radiations revealed their identities with the characteristic “secondary” radiations which Barkla and Sadler had then recently discovered. The experiments described in the present paper are an extension of the above, and were carried out partly at the Cavendish Laboratory in 1908 and partly at the National Physical Laboratory just prior to the war. The writer’s military duties have prevented the continuation of the work, and the results are now put on record in the hope that they may help to further the progress of the subject, to which the more precise method of the crystal-spectrometer has given a great impetus from a different point of view.

scholarly journals I. The behaviour of single crystals of aluminium under static and repeated stresses

1927 ◽  
Vol 226 (636-646) ◽  
pp. 1-30 ◽  
Keyword(s):  
Single Crystals ◽  
National Physical Laboratory ◽  
Micro Structure ◽  
Important Conclusion ◽  
X Ray ◽  
Slip Bands ◽  
Physical Laboratory ◽  
Slip Planes ◽  
Experimental Facilities ◽  
Crystalline Aggregates

In a previous paper were recorded the results of an investigation into the effects of repetitions of stress on the micro-structure of various metals in the form of crystalline aggregates, the main purpose of the investigation being a study of the causes of fracture under repeated stresses of relatively low magnitude. One important conclusion derived from the experiments was that the action of slipping was not, as had been previously stated, a weakening process in itself. Up to a point the effect of slip was actually to increase the resistance of the metal to further slip. Eventually, however, this strengthening action was exhausted, and failure commenced by the formation of a crack. It was suggested that failure occurred when the amount of strain-hardening by slip exceeded a certain limiting amount. No definite evidence could be obtained on this point, but it was considered that further information might be obtained if attention was directed to a material more simple in structure than a crystalline aggregate. In particular, it was desired to eliminate the effects of the crystal boundaries, whose nature is at present unknown. This could be accomplished if specimens cut entirely from one crystal were employed. Further, it should be possible to verify the assumption, commonly made, that slip bands represent the traces of actual “slip planes” on the surface of the specimen, and to relate these with the atomic structure of the material. Through the kindness of Prof. Carpenter and Miss Elam a number of large single crystals of aluminium were prepared and presented and have been used throughout this work. At that time the necessary experimental facilities for X-ray work were not available to the authors at the National Physical Laboratory. Prof. Carpenter offered to arrange for the X-ray analyses to be undertaken by his assistant, Miss C. F. Elam, at the Royal School of Mines. This offer was gratefully accepted and the authors are greatly indebted to Miss Elam for carrying out this section of the work.

scholarly journals The application of X-rays to the study of alloys

1925 ◽  
Vol 108 (748) ◽  
pp. 643-654 ◽  
Keyword(s):  
Single Crystals ◽  
National Physical Laboratory ◽  
Photographic Method ◽  
X Rays ◽  
X Ray ◽  
Powder Method ◽  
Physical Laboratory ◽  
Small Crystals ◽  
Ray Methods ◽  
Great Advance

Since the middle of last century it has been known that the alloys, obtained by melting together two or more metals, are conglomerates of small crystals. As it is impossible to study them under the polarizing microscope because of their high absorbing power for light, and as they are seldom obtained in crystals with faces sufficiently well developed to allow a measurement of their angles, our crystallographic knowledge has been, until recently, extremely small. When, therefore, the X-ray methods came to the assistance of the metallurgist they were sure of a welcome. In 1922, Bain, using the powder-photograph method of Debye and Hull, carried out some very important pioneering work. In 1924, Owen and Preston, of the National Physical Laboratory, working in conjunction with Rosenhain studied the Cu-Al and Cu-Zn systems. They used a powder method with an ionization spectrometer. Their work marked a great advance, on account of the precision of their measurements and their detailed description of the preparation of the samples of alloys. At the same time Westgren and Phragmen, working in Stockholm with a photographic method, studied independently the same systems as Owen and Preston, and obtained results of equal precision. They extended the work in certain directions by making a more thorough investigation of single crystals. They have now undertaken an extensive research on several alloys and on steels.

Recent Developments in National Physical Laboratory X-Ray Gratings and Spectrometers

1976 ◽  
Vol 15 (3) ◽  
Author(s):  
A. Franks ◽  
D. W. Butler ◽  
B. Gale ◽  
M. Stedman ◽  
P. R. Stuart
Keyword(s):  
National Physical Laboratory ◽  
X Ray ◽  
Physical Laboratory ◽  
Recent Developments
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