摘要:

Electron beam lithography means writing patterns in thin films of electron sensitive material using a finely focused (sub-micrometre diameter) electron beam. By combining electrical scanning with interferometrically monitored mechanical motion, very complex patterns can be generated with great accuracy; for example, a pattern containing one-micrometre features can extend over 100 mm with a positional accuracy of 025 μm. In the manufacture of integrated circuits this technique is used for generating masks which are then projected optically onto silicon wafers which are coated with photosensitive resists. For making circuits with sub-micrometre features the resist-coated wafer can be exposed directly with the electron beam; however this is slow because the electron beam exposure is point-by-point and there are limits to electron beam intensity and resist sensitivity. Overcoming this limit is possible using techniques which allow the exposure of many points simultaneously but such techniques are not yet widespread. Competing techniques are ion beam lithography and X-ray lithography.

ISSN:0010-7514    

DOI:10.1080/00107518108231531

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The 12 member states of the European high energy physics laboratory CERN are considering the construction of a huge new accelerator. This article outlines our understanding of the fundamental forces of nature and the subnuclear structure of matter, and describes the accelerator that will enable some of their mysteries to be explained.

ISSN:0010-7514    

DOI:10.1080/00107518108231532

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

This article reviews the present status of superradiance in atoms and molecules. The introductory section describes the important physical properties of superradiant emission, and presents the important experimental features. A simple theoretical formulation, based on the coupled Maxwell-Schrödinger equations, is described. Simple expressions for observable output parameters are given, valid in experimentally relevant regimes. These results are compared with superradiance experiments performed at a wide range of wavelengths in numerous laboratories since 1973. While the principal features of superradiance are generally agreed upon, details of the initiation of the radiation process and of the observed ringing are still under study.

ISSN:0010-7514    

DOI:10.1080/00107518108231533

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The recent gauge theory of strong interactions known as quantum chromodynamics is compared to the earlier gauge theory of quantum electrodynamics. Some important properties of quantum chromodynamics, such as asymptotic freedom, are discussed, and some consequences and current limitations of the theory are pointed out.

ISSN:0010-7514    

DOI:10.1080/00107518108231534

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Earthquake risk is the combination of three factors: the earthquake hazard, the loss potential and the vulnerability. To examine the risk it is first necessary to consider the global distribution of earthquakes, their size and their frequency of occurrence. Migratory trends and temporal patterns of activity are sought as a means of defining the locations of future seismic hazard. It is important also to appreciate the kind of damage that is brought about by an earthquake, including the social and economic effects that can follow. Where loss potential is high, in areas of high population density, and where there is a known hazard from earthquakes, it is vital to mitigate the risk by reducing the vulnerability so far as possible. This can best be achieved through earthquake-resistant construction of buildings and other structures, but there are limits to what can be achieved. Consequently earthquake prediction may prove an alternative, complementary approach that could at least save lives. A range of possible precursory phenomena have been discovered, a number of which can be related empirically to the size and time ahead of an impending earthquake, but since the physical mechanism of earthquakes is still poorly known, these phenomena have only a weak scientific basis. At present none are established as definite precursors, and although a few successful predictions have been claimed, there are too many failures to predict, and too many false alarms, for Predictions to be reliable or credible. For the time being, as research progresses, the uncertainty of predictions will pose problems for scientists and government authorities alike.

ISSN:0010-7514    

DOI:10.1080/00107518108231535

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The article concentrates mainly on the developing pattern of safety thinking and safety practices which have been brought about by, and in turn have influenced, the growth of modern industrial technology, particularly in the nuclear field.

ISSN:0010-7514    

DOI:10.1080/00107518108231536

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518108231537

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518108231538

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A Portrait of Isaac Newton. By F. E. Manuel. (Frederic Muller, 1980.) [Pp. xvi + 478.] £11.75.

ISSN:0010-7514    

DOI:10.1080/00107518108231539

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/00107518108231540

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor