Page 34 - Summer 2024

(g) Gamma Radiography
Everyone is familiar with the general application REFERENCES
of X-rays or gamma rays in the field of radiography.
The less energetic the X-rays, the more definition one 1 W. J. Arrol, J. Wilson, C. Evans, J. Chadwick, J. Eakins. 4 H. J. Wedge. Oil and Gas Journal. Vol. 54 (17), p. 77.
The Preparation and Possible Industrial Uses of Kryp-
1954.
can achieve when radiographing thin and moderately ton 85 and Tritium.” Radioisotopes Conference, P.54, 5 W. 5. Arrol, S. Jefferson. Brit. Pat. No. 738,182.
low density materials. For instance, Thulium 170 emits 1954. Butterworths Scientific Publication, London. 6 M. M. Kannuna, J. F. Cameron. “The Use of Tritium
gamma rays of only 84 KeV energy, and will provide 2 E. J. Wilson, H. P. Dibbs, S. Richards, J. D. Eakins. Brehmsstrahlmg for the Determination of Sulphur in
very highly defined radiographs of the bone structure “Preparation of Xenon 133 Radiography Sources from Hydrocarbons. I. J.A.R.I., 1957. Vol. 2, p. 76.
Spent Fuel.” Nucleonics, Vol. 16 (4), p. 110. 1958.
of the body. In order to achieve a suitable radiograph 3 E. J. Wilson. “Manipuption of Radioactive Gases in 7 E. J. Wilson, J. D. H. Hughes. “Atomic Lamps.” The
in the shortest possible time, not only must the strength High Vacuum Apparatus. Vacuum, Vol. IV (3), p. 303. Municipal Journal, No. 3395, 14th March, 1958.
of the source be high, but it must be placed as near the 1954 (published Feb., 1957). 8 C. G. Clayton. In Press.
medium as possible, and accordingly, the source must
be concentrated into the smallest volume possible. The
chief disadvantage of Tm is the build up of energetic
brehmsstrahlung or X-rays of energies up to 1 MeV as
the activity of the source is increased. This effectively Membership Elections
reduces the definition of the subsequent radiograph. On
the other hand, Xenon 133 sources with a similar
gamma ray energy do not emit appreciable amounts of The following recent elections have been recorded in the Membership Register of the Institution of
these more energetic rays, so the radiograph remains Electronics:--
highly defined even with higher activity sources. How-
ever, the short half life of the radioisotopes limits its
application in this field. Direct Election to Member:-
It is very unlikely that radioisotopes will compete LISSIMORE, John Philip. Littleover.
with X-ray tubes in attaining the precise exposures
required in clinical radiography, but when X-ray
machines are inconvenient, for example in field condi- Direct Election to Associate Member:-
tions, the above mentioned sources could well prove ACKROYD, Brian R. Streatham. IVERS, George J. Manchester.
particularly applicable. Fig. 5. A Krypton 85 Light Source. ARCHER, Peter. Willerby. JOHNSON, Geoffrey. Stanks.
(h) Atomic Light Sources Although lamps have been prepared in laboratory BAILEY, John E. Chessington . LAZENBY, Brian D. Hull.
The emission of light from phosphors bombarded by conditions which can be seen some 500 or more yards BAKER, Harold F. Mobberley. LEE, Melvin. Huddersfield.
atomic particles is a familiar application to all those away, and have sufficient intensity to make newsprint BLAND, Sheffield.
people possessing watches or alarm clocks with lumin- legible 2-3 feet away in the dark, they will never com- Cecil A. Wilmslow . McATEER, Brian A.
ous dials. A phosphor is a particular type of solid pete with electric light for brightness. Consequently, BOOTH, Harold M. lrby. McCARTHY, Brian D. Catford.
capable of converting absorbed energy, which may the applications are limited to dark room markers, BROWN, Adam G. Giffnock PANRUCKER, Robin N. Stretford.
come from ultra violet rays or the bombarding particles markers in mines, ammunition dumps, ships and aero- BROWN, John. Wythenshawe. PARRY, Alexander E. Baginton.
mentioned above, into light rather than into heat, which planes, certain low intensity signalling lights on rail-
occurs with all other types of organic or inorganic com- ways, short distance marine buoys, etc. They require CLARK, Kenneth J. Foleshill. PENDRY, John K. Chester.
pounds. By increasing the number of bombarding no maintenance, no power sources and consequently no COYNE, John H. Letchworth. PRICKETT, Brian R. Chorlton-cum-Hardy.
particles the amount of light or the brightness of the cables, are completely safe in an inflammable atmos- CROSS, Martin D. Swindon. ROBERTS, Gordon. Huddersfield.
source increases. Unfortunately, the very energetic and phere and long lasting. Since the gases are compara-
comparatively massive particles do have a deleterious tively inert, the inadvertent breakage of a source will DAVIES, Hubert H. Fareham. SCHROEDER, Henry A. Australia.
effect on the phosphor crystals, so as to decrease the constitute little danger if in fairly large rooms or in the ELLIOTT, Henry R. Larkhill. SHAWEESH, Hamzeh M. Jordan.
amount of light emitted. Over a period of a few open air the gas is allowed to disperse quickly'. A FALCONER, John E. A. Upper Batley. SMITH, William. Cosford.
months the brightness of the luminous paint will drop typical atomic lamp is illustrated in Fig. 5. HEANLY, Michael A. C. Rochdale. UNSWORTH, Walter. Atherton.
by 50% or more. When the bombarding particle is
replaced by a beta particle this destructive effect is not CONCLUSION HEASON, Brian. Staple ford. WHITE, John J. Birkenhead.
so noticeable, and considerably brighter sources can be There is every indication that radioactive gases will IRELAND, Leslie. Hyde.
produced which only decrease their light intensity as play a very important part in the future programme of
the activity decays away. radioisotopes in industry. Krypton 85, in particular, is
Both tritium and krypton 85 are two radioisotopes a waste product from reactors and as more civil react- Direct Election to Associate:-
ors are constructed so the availability of the radioisitope
which are particularly useful for such an application. increases and the cost decreases. In addition, the gas BOARDMAN, James W. Canada. SCOTT, Alban. Brough.
Both possess reasonably long half lives, so that the light is inert and therefore not retained by the body when CLARK, Stanley. Shefield. TAYLOR, Donald. Middleton.
intensity will only drop by one half in 10 years, to a inhaled. Since stringent precautions are always adopted Sheffield. Longsight.
quarter in 20 years, to one eighth in 30 years, and so on. to seal all types of radioisotopes, used in industry, there GLASSBY, Brian. THORP, Peter A.
The atomic lights are prepared from metal, glass or will be no more difficulty in sealing a gas compared to JUDD, Frederick C. South Woodford. WOODVINE, Ronald. Leeds.
Perspex in the form of cups or bulbs, with a thin layer a solid. A source containing an inert gas will have RICHARDSON, Eric. Newcastle-upon- Tyne.
of phosphor lining the containers. A window of suit- the additional advantage of not constituting any form
able glass or Perspex allows the light to penetrate from of contamination hazard in the unfortunate event of a
a hermetically sealed lamp filled with the radioactive source being damaged by unqualified personnel or by Student Registrations:-
gas. fire. HO!,LINSHEAD, Alan G. Rochdale. YORKE, Stanley R. Morden.

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