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318. Heat-reflecting windows using gold and bismuth oxide films
Abstracts 309--319 31 309. Some Properties of a Graded Vacuum Spark Gap. J. W. Mathers and A. H. Williams, Rev. Sci. Instrum., 31 : 3, 297-303. 31 : 18 Thermlonie Properties of Thorium Deposits on Control Grid Materials. See Abstract No. 249.
32.
Nucleonics
32 310. Cern Proton Synchrotron. Engineer, 209, 5429, 277-278, Feb. 1960; 209, 5430, 315-318, Feb. 1960.
353
33 315. Accuracy of Selected-Area Microdiffraction in the Electron Microscope. United Kingdom. Because of the spherical aberration at the objective lens, the area of an object defined by the selector aperture for microdiffraction experiments does not exactly correspond to the actual parts of the specimen contributing to the pattern. Further errors may arise through incorrect lens settings. The magnitude of the possible errors and the electronoptical explanation are discussed. The theoretical results are in reasonable agreement with the experimentally observed errors. It is concluded that especial care is required in studies of thin metal foils where mis-orientations between grains are being measured. A. W. Agar, Brit. J. Appl. Phys., 11, 185-189, May 1960.
32
311. Large Double-Focusing Mass Spectrometer. Engineer, 209, 5435, 547-548, March 1960. 32 : 33 : 1 0 : 2 0 : 2 7 Summarized Proceedings of a Symposium on Current Developments in the Production of High Vacua. See Abstract No. 207. 32 : 33 : 19 Absolute Intensity Measurements of the Carbon and Aluminium X-Ray K-Lines with a Proportional Counter. See Abstract No. 253. 32 : 30 Deposition by Thermal Evaporation of Thin Films of Titanium and Zirconium for Tritium Targets. See Abstract No. 299.
Simple Evaporator for Radioactive Metals. 33.
32 : 30 See Abstract No. 302.
G e n e r a l P h y s i c s and E l e c t r o n i c s
33 312. Method for Size-Distribution Determination of NonVolatile Droplets by Electron Microscopy. United Kingdom. The droplets are sampled on a thin wet film of gelatin solution and washed away when the gelatin has set. Replicas are taken of the impressions left by the spread out droplets. The replica diameters are converted to droplet diameters by the application of a spread factor which although determined for larger droplets by light microscopy may be reliably applied to droplets in the electron microscope size range. W. J. Harris, Brit. J. Appl. Phys., 10, 139-140, Mar. 1959. 33 313. Summarized Proceedings of a Conference on Electron Microscopy, Bangor, September 1957. United Kingdom. The Annual Conference of the Electron Microscopy Group of The Institute of Physics was held in the Department of Botany, University College of North Wales, Bangor, from 10 to 12 September 1957. The papers presented, and discussion on them, are summarized in this report. Report on the Conference on Electron Microscopy, Sept. 1957, Brit. J. AppL Phys., 9, 306--311, Aug. 1958. 33 314. Reflexion Electron Microscopy Using Diffracted Electrons. United Kingdom. Crystalline surfaces have been examined in the reftexion electron microscope with the angles of illumination and viewing adjusted so that diffracted electrons contributed to the images. In this way, the size and distribution of the diffracting regions have been determined. A resolution of 80/l~ has been obtained, which is at least four times better than that obtained in normal reflexion micrographs. J. S. Halliday, Brit. J. Appl. Phys., 11, 158-162, April 1960.
33 316. Selected Area Microdiffraction in the Electron Microscope. Note by A. W. Agar, Brit. J. Appl. Phys,, 9, 419, Oct. 1958. 33 317. The Theory of Ballast Tubes or Barretters. United Kingdom. The theory is based on a simple graphical method of solving the equation of thermal equilibrium of an electrically heated wire in a gas-filled enclosure. The results account for the main operating characteristics and have accurately predicted the ratings of various low voltage barretters. It is also shown why, in practice, barretters have always consisted of an iron wire in hydrogen. R. O. Jenkins, Brit. J. Appl. Phys., 9, 391-394, Oct. 1958. 33 : 37 318. Heat-Reflecting Windows Using Gold and Bismuth Oxide Films. United Kingdom. Thin gold films sandwiched between certain metal oxide layers possess a high electrical conductivity and high optical transparency. They also have a high infra-red reflectance and may be used as transparent heat-reflecting coatings if their yellowish tinted colour in transmitted light can be tolerated. The observation window of an enclosure exposed to infra-red radiation was coated with different film combinations, and their effectiveness in reducing the internal temperature rise determined. The reflectance and transmittance of the coatings were measured at A -- 0.56t~ and in the infra-red region using a photometer with a broad bandwidth (0.8-2~). Results are given for the following : plain glass ; a high reflecting bismuth oxide film on glass ; gold film on glass ; and gold films sandwiched between bismuth oxide and silicon monoxide coatings. Optimum performance was obtained with a Bi203/Au/Bi~O.~ multi-layer of 450/130/450 A thickness which had a transmittance of 73 per cent for green light and a reflectance of 74 per cent in the near infra-red region, compared with values of 55 and 35 per cent respectively for a gold film of the same thickness without the oxide layers. L. Holland and G. Siddall, Brit. J. Appl. Phys., 9, 359-361, Sept. 1958. 33 319. The Ageing of Vacuum Standard Lamps on a.c. and d.c. United Kingdom. A comparison is made of the rates of fall of luminous intensity and current, at constant voltage and colour temperatures 2390°K approximately, of 100 V 3 0 W vacuum photometric standard lamps, on a.c. and d.c. supplies. The rate for intensity is considerably higher on d.c. than on a.c., while the rate for current is lower. These specific effects of d.c. operation can be accounted for simply by changes in filament emissivity. There is no necessity to postulate a migration of tungsten along the surface of the filament, as in the authors" previous work on gas-filled lamps. The effects are shown to be almost fully reversible, after many hours of burning, by suitable application of reversed d.c., and a.c., supplies. As for gas-filled
32.
Nucleonics
32 310. Cern Proton Synchrotron. Engineer, 209, 5429, 277-278, Feb. 1960; 209, 5430, 315-318, Feb. 1960.
353
33 315. Accuracy of Selected-Area Microdiffraction in the Electron Microscope. United Kingdom. Because of the spherical aberration at the objective lens, the area of an object defined by the selector aperture for microdiffraction experiments does not exactly correspond to the actual parts of the specimen contributing to the pattern. Further errors may arise through incorrect lens settings. The magnitude of the possible errors and the electronoptical explanation are discussed. The theoretical results are in reasonable agreement with the experimentally observed errors. It is concluded that especial care is required in studies of thin metal foils where mis-orientations between grains are being measured. A. W. Agar, Brit. J. Appl. Phys., 11, 185-189, May 1960.
32
311. Large Double-Focusing Mass Spectrometer. Engineer, 209, 5435, 547-548, March 1960. 32 : 33 : 1 0 : 2 0 : 2 7 Summarized Proceedings of a Symposium on Current Developments in the Production of High Vacua. See Abstract No. 207. 32 : 33 : 19 Absolute Intensity Measurements of the Carbon and Aluminium X-Ray K-Lines with a Proportional Counter. See Abstract No. 253. 32 : 30 Deposition by Thermal Evaporation of Thin Films of Titanium and Zirconium for Tritium Targets. See Abstract No. 299.
Simple Evaporator for Radioactive Metals. 33.
32 : 30 See Abstract No. 302.
G e n e r a l P h y s i c s and E l e c t r o n i c s
33 312. Method for Size-Distribution Determination of NonVolatile Droplets by Electron Microscopy. United Kingdom. The droplets are sampled on a thin wet film of gelatin solution and washed away when the gelatin has set. Replicas are taken of the impressions left by the spread out droplets. The replica diameters are converted to droplet diameters by the application of a spread factor which although determined for larger droplets by light microscopy may be reliably applied to droplets in the electron microscope size range. W. J. Harris, Brit. J. Appl. Phys., 10, 139-140, Mar. 1959. 33 313. Summarized Proceedings of a Conference on Electron Microscopy, Bangor, September 1957. United Kingdom. The Annual Conference of the Electron Microscopy Group of The Institute of Physics was held in the Department of Botany, University College of North Wales, Bangor, from 10 to 12 September 1957. The papers presented, and discussion on them, are summarized in this report. Report on the Conference on Electron Microscopy, Sept. 1957, Brit. J. AppL Phys., 9, 306--311, Aug. 1958. 33 314. Reflexion Electron Microscopy Using Diffracted Electrons. United Kingdom. Crystalline surfaces have been examined in the reftexion electron microscope with the angles of illumination and viewing adjusted so that diffracted electrons contributed to the images. In this way, the size and distribution of the diffracting regions have been determined. A resolution of 80/l~ has been obtained, which is at least four times better than that obtained in normal reflexion micrographs. J. S. Halliday, Brit. J. Appl. Phys., 11, 158-162, April 1960.
33 316. Selected Area Microdiffraction in the Electron Microscope. Note by A. W. Agar, Brit. J. Appl. Phys,, 9, 419, Oct. 1958. 33 317. The Theory of Ballast Tubes or Barretters. United Kingdom. The theory is based on a simple graphical method of solving the equation of thermal equilibrium of an electrically heated wire in a gas-filled enclosure. The results account for the main operating characteristics and have accurately predicted the ratings of various low voltage barretters. It is also shown why, in practice, barretters have always consisted of an iron wire in hydrogen. R. O. Jenkins, Brit. J. Appl. Phys., 9, 391-394, Oct. 1958. 33 : 37 318. Heat-Reflecting Windows Using Gold and Bismuth Oxide Films. United Kingdom. Thin gold films sandwiched between certain metal oxide layers possess a high electrical conductivity and high optical transparency. They also have a high infra-red reflectance and may be used as transparent heat-reflecting coatings if their yellowish tinted colour in transmitted light can be tolerated. The observation window of an enclosure exposed to infra-red radiation was coated with different film combinations, and their effectiveness in reducing the internal temperature rise determined. The reflectance and transmittance of the coatings were measured at A -- 0.56t~ and in the infra-red region using a photometer with a broad bandwidth (0.8-2~). Results are given for the following : plain glass ; a high reflecting bismuth oxide film on glass ; gold film on glass ; and gold films sandwiched between bismuth oxide and silicon monoxide coatings. Optimum performance was obtained with a Bi203/Au/Bi~O.~ multi-layer of 450/130/450 A thickness which had a transmittance of 73 per cent for green light and a reflectance of 74 per cent in the near infra-red region, compared with values of 55 and 35 per cent respectively for a gold film of the same thickness without the oxide layers. L. Holland and G. Siddall, Brit. J. Appl. Phys., 9, 359-361, Sept. 1958. 33 319. The Ageing of Vacuum Standard Lamps on a.c. and d.c. United Kingdom. A comparison is made of the rates of fall of luminous intensity and current, at constant voltage and colour temperatures 2390°K approximately, of 100 V 3 0 W vacuum photometric standard lamps, on a.c. and d.c. supplies. The rate for intensity is considerably higher on d.c. than on a.c., while the rate for current is lower. These specific effects of d.c. operation can be accounted for simply by changes in filament emissivity. There is no necessity to postulate a migration of tungsten along the surface of the filament, as in the authors" previous work on gas-filled lamps. The effects are shown to be almost fully reversible, after many hours of burning, by suitable application of reversed d.c., and a.c., supplies. As for gas-filled