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The physics of computer elements
128
Classified Abstracts 219--232
30 : 58 219. New technique for the direct investigation of fission events. United States. A method for the electron microscopic study of individual fission events in ~sU has been developed. The experimental procedure is as follows : A film of pure aluminium (2S) is evaporated in vacuum (10 5~ of mercury with helium as a residual gas) on to the surface of a sodium chloride cleavage face to a thickness of about 50/~. On this is evaporated a film of ~nU, calculated to be 10/~ in thickness, which is covered with an additional film of aluminium, 50/~ in thickness. This uranium " sandwich " is sealed in an aluminium capsule in oxygen, oxygen-free argon or helium and irradiated by thermal neutrons to an integrated flux, 2.8 × 101~ neutrons/cm ~. After the specimen cools to about 50 mr. it is removed from the capsule, and the metal composite is floated off the sodium chloride on distilled water and mounted on copper grids. Upon examination in the electron microscope light track-like marks are seen in a darker matrix. Micrographs at 140,000 magnifications show these tracks to be 100/~ in average width, 100 to 20,000/~ in length, and invariably of higher electron " transparency " than the matrix. The matrix is composed of atomic aggregates (micro-crystals) of aluminium, randomly oriented. Electron diffraction patterns show sharp aluminium rings, with vague traces of diffuse Al~O3. No uranium rings are visible due to the small quantity of uranium atoms per unit volume. The aluminium crystallites are 50/~ in size and very uniform. The tentative interpretation of the results of these experiments is that the tracks are produced by fission fragments. The visible effect is probably due to vaporization of aluminium atoms along the path of the fission fragment. A crude calculation of the energy transferred along such a path in aluminium of 100/~ thickness shows this to be quite probable. These tracks do not anneal out nor change appearance after heating for 15 min. at 250~C in a helium atmosphere nor with prolonged heating in the electron beam. Experiments have been performed using copper, platinum and silver as the matrix, all of which show much the same appearance. (Authors, modified) J. J. Kelsch, O. F. Kammerer and P. A. Buhl, Brit. J. Appl. Phys., 11 (12), Dec. 1960, 555. 30 : 33 220. The preparation of thin films of germanium and silicon. Great Britain. Films about 1000~ thick, suitable for observing dislocations by transmission electron microscopy, have been prepared from the brittle semiconductors germanium and silicon by a combination of mechanical polishing and chemical etching. (Author) B. A. Irving, Brit. J. Appl. Phys., 12 (3), March 1961, 92-93. 30 221. Measurement of thickness of thin transparent films using fluorescence. Great Britain. A molecular fluorescence method of comparing the thickness of transparent films (in the range 3 × 10 -6 to 10 -~ cm) is described. An instrument for use in the middle of this range (10 -4 cm) is also described and results show that its accuracy is to better than ± 2 per cent. (Author) B. P. Bunt, Brit. J. Appl. Phys., 12 (4), April 1961, 175-177. 30 222. The physics of computer elements. Great Britain. The main requirements of a computing machine are that it should be able to receive and store information, perform logical operations on the information and finally to produce some form of useful output. Some interesting techniques employed in satisfying these requirements are described together with the physical phenomena on which they depend. The main use of novel techniques is in the storage of information and various systems are examined which depend on different physical principles. The following types of system are considered: acoustic, electrostatic, magnetic, optical and super-
conducting. It is considered that at present magnetic or superconducting devices employing thin films show most promise for the development of high speed devices. (Author) C. N. W. Litting, Brit. J. Appl. Phys., 12 (5), May 1961, 207-213. 3O 223. Use of helium flush in the vacuum deposition of thin films. Canada. Silver films deposited in a vacuum chamber previously flushed with an inert gas, helium, exhibit less aggregation as shown in electron micrographs and reduced ageing as determined from electrical conductivity, as compared with films produced under the usual high vacuum procedures. It is concluded that in general flushing the vacuum chamber with helium is of value in producing stable, compact and pure evaporated films. (Author) G. N. Srivastava, Brit. J. Appl. Phys., 12 (5), May 1961, 255-256. 30 224. Spin wave resonance in Cu-Ni alloy films. H. Nose, J. Phys. Soc. Japan, 16 (2), Feb. 1961, 342. 3O 225. Magnetic anisotropy of evaporated films. I. Iron films formed in magnetic field. M. Takahashi, D. Watanabe, T. Sasagawa, T. Kono and S. Ogawa, J. Phys. Soc. Japan, 16 (I1), Nov. 1961, 1913-1923. 30 226. Magnetic-film storage for digital computers. Great Britain. A storage device is described which consists of a thin film (five millionths of an inch) of a magnetic alloy deposited on a fiat panel ; the layer is deposited in a vacuum on a three-in.-square base plate. Each plate stores 1000 bits and the device is, it is claimed, a thousand times as fast as existing stores. (Author, modified) Anon., New Scientist, 9 (224), 2 March 1961, 541. 3O 227. Thin dielectrics. U.S.S.R. Thin films of boron oxide have been made by decomposing triethyl borate at a temperature of 700-900°C in a vacuum system and depositing the oxide on to thin sheets of tantalum, tungsten or nickel. A deposit of the order of 1.3t~ can be completed in ten minutes. (Author, modified) Anon., New Scientist, 10 (235), 18 May 1961, 391. 3O 228. Thin magnetic films for very fast computers. R. V. Peacock, New Scientist, 11 (245), 27 July 1961, 224-226. 3O 229. On the production of silver apertures by the vacuum evaporation technique. C. E. Anthony and L. E. Preuss, Vacuum, 9 (3/4), May/July 1959, 232. 30 : 38 230. Vacuum distillation source image formation by surface sensitization. L. E. Preuss, Vacuum, 9 (3/4), May/July 1959, 233. 30 : 37 231. Vacuum evaporation of Cu, Ag, Sn, Fe and Cr from a TiC heater. S. Tabata and M. Iwata, Vacuum, 11 (1), Jan. 1961, 36-37. 3O 232. A comparison between the evaporation characteristics of a crucible and a ring source. United States. The properties of evaporated films largely depend on the uniformity of the evaporation parameters achieved
Classified Abstracts 219--232
30 : 58 219. New technique for the direct investigation of fission events. United States. A method for the electron microscopic study of individual fission events in ~sU has been developed. The experimental procedure is as follows : A film of pure aluminium (2S) is evaporated in vacuum (10 5~ of mercury with helium as a residual gas) on to the surface of a sodium chloride cleavage face to a thickness of about 50/~. On this is evaporated a film of ~nU, calculated to be 10/~ in thickness, which is covered with an additional film of aluminium, 50/~ in thickness. This uranium " sandwich " is sealed in an aluminium capsule in oxygen, oxygen-free argon or helium and irradiated by thermal neutrons to an integrated flux, 2.8 × 101~ neutrons/cm ~. After the specimen cools to about 50 mr. it is removed from the capsule, and the metal composite is floated off the sodium chloride on distilled water and mounted on copper grids. Upon examination in the electron microscope light track-like marks are seen in a darker matrix. Micrographs at 140,000 magnifications show these tracks to be 100/~ in average width, 100 to 20,000/~ in length, and invariably of higher electron " transparency " than the matrix. The matrix is composed of atomic aggregates (micro-crystals) of aluminium, randomly oriented. Electron diffraction patterns show sharp aluminium rings, with vague traces of diffuse Al~O3. No uranium rings are visible due to the small quantity of uranium atoms per unit volume. The aluminium crystallites are 50/~ in size and very uniform. The tentative interpretation of the results of these experiments is that the tracks are produced by fission fragments. The visible effect is probably due to vaporization of aluminium atoms along the path of the fission fragment. A crude calculation of the energy transferred along such a path in aluminium of 100/~ thickness shows this to be quite probable. These tracks do not anneal out nor change appearance after heating for 15 min. at 250~C in a helium atmosphere nor with prolonged heating in the electron beam. Experiments have been performed using copper, platinum and silver as the matrix, all of which show much the same appearance. (Authors, modified) J. J. Kelsch, O. F. Kammerer and P. A. Buhl, Brit. J. Appl. Phys., 11 (12), Dec. 1960, 555. 30 : 33 220. The preparation of thin films of germanium and silicon. Great Britain. Films about 1000~ thick, suitable for observing dislocations by transmission electron microscopy, have been prepared from the brittle semiconductors germanium and silicon by a combination of mechanical polishing and chemical etching. (Author) B. A. Irving, Brit. J. Appl. Phys., 12 (3), March 1961, 92-93. 30 221. Measurement of thickness of thin transparent films using fluorescence. Great Britain. A molecular fluorescence method of comparing the thickness of transparent films (in the range 3 × 10 -6 to 10 -~ cm) is described. An instrument for use in the middle of this range (10 -4 cm) is also described and results show that its accuracy is to better than ± 2 per cent. (Author) B. P. Bunt, Brit. J. Appl. Phys., 12 (4), April 1961, 175-177. 30 222. The physics of computer elements. Great Britain. The main requirements of a computing machine are that it should be able to receive and store information, perform logical operations on the information and finally to produce some form of useful output. Some interesting techniques employed in satisfying these requirements are described together with the physical phenomena on which they depend. The main use of novel techniques is in the storage of information and various systems are examined which depend on different physical principles. The following types of system are considered: acoustic, electrostatic, magnetic, optical and super-
conducting. It is considered that at present magnetic or superconducting devices employing thin films show most promise for the development of high speed devices. (Author) C. N. W. Litting, Brit. J. Appl. Phys., 12 (5), May 1961, 207-213. 3O 223. Use of helium flush in the vacuum deposition of thin films. Canada. Silver films deposited in a vacuum chamber previously flushed with an inert gas, helium, exhibit less aggregation as shown in electron micrographs and reduced ageing as determined from electrical conductivity, as compared with films produced under the usual high vacuum procedures. It is concluded that in general flushing the vacuum chamber with helium is of value in producing stable, compact and pure evaporated films. (Author) G. N. Srivastava, Brit. J. Appl. Phys., 12 (5), May 1961, 255-256. 30 224. Spin wave resonance in Cu-Ni alloy films. H. Nose, J. Phys. Soc. Japan, 16 (2), Feb. 1961, 342. 3O 225. Magnetic anisotropy of evaporated films. I. Iron films formed in magnetic field. M. Takahashi, D. Watanabe, T. Sasagawa, T. Kono and S. Ogawa, J. Phys. Soc. Japan, 16 (I1), Nov. 1961, 1913-1923. 30 226. Magnetic-film storage for digital computers. Great Britain. A storage device is described which consists of a thin film (five millionths of an inch) of a magnetic alloy deposited on a fiat panel ; the layer is deposited in a vacuum on a three-in.-square base plate. Each plate stores 1000 bits and the device is, it is claimed, a thousand times as fast as existing stores. (Author, modified) Anon., New Scientist, 9 (224), 2 March 1961, 541. 3O 227. Thin dielectrics. U.S.S.R. Thin films of boron oxide have been made by decomposing triethyl borate at a temperature of 700-900°C in a vacuum system and depositing the oxide on to thin sheets of tantalum, tungsten or nickel. A deposit of the order of 1.3t~ can be completed in ten minutes. (Author, modified) Anon., New Scientist, 10 (235), 18 May 1961, 391. 3O 228. Thin magnetic films for very fast computers. R. V. Peacock, New Scientist, 11 (245), 27 July 1961, 224-226. 3O 229. On the production of silver apertures by the vacuum evaporation technique. C. E. Anthony and L. E. Preuss, Vacuum, 9 (3/4), May/July 1959, 232. 30 : 38 230. Vacuum distillation source image formation by surface sensitization. L. E. Preuss, Vacuum, 9 (3/4), May/July 1959, 233. 30 : 37 231. Vacuum evaporation of Cu, Ag, Sn, Fe and Cr from a TiC heater. S. Tabata and M. Iwata, Vacuum, 11 (1), Jan. 1961, 36-37. 3O 232. A comparison between the evaporation characteristics of a crucible and a ring source. United States. The properties of evaporated films largely depend on the uniformity of the evaporation parameters achieved