ISSN:1044-8632    

DOI:10.1080/10448639208218763

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Approximately every 18 months the UK's Science and Engineering Research Council (SERC) sponsors a meeting of the UK neutron and muon users, and on 2–3 April 1992 it was held at Reading University. A totalof ∼200scientistsattended, including 70 students, and74posters were presented.

ISSN:1044-8632    

DOI:10.1080/10448639208218764

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The idea for the Workshop on Neutron and Synchrotron Radiation Studies of Materials grew out of our conversations with materials scientists in recent years. There is an initial barrier to ‘user- mode’ research that must be overcome by potential first time users of facilities such as the HFBR and NSLS. Many groups, realizing the power of these tools in materials characterization, would like to try a few experiments to judge their relevance to their own work, but are put off by a perception that the techniques are esoteric and best left to the specialists in x-ray or neutron scattering. This is untrue for many of the techniques most useful in the first characterization of new materials, e.g. powder diffraction, small angle scattering, X-ray absorption spectroscopy, and nothing exposes this misconception as thoroughly as a little first hand experience. Fortunately, the Center of Excellence for the Synthesis and Processing of Advanced Materials, a new program financed by the US. Department of Energy, agreed and provided the funding for this Workshop. The Workshop organizers were J. Hastings, S. Hulbert, S. Shapiro, R. Thomas and myself. R. Greenberg was the Workshop Coordinator. In overall concept the Workshop was patterned after the more ambitious HERCULES Workshops held in Grenoble for the last two years.

ISSN:1044-8632    

DOI:10.1080/10448639208218765

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The second meeting of the International Group on Research Reactors, which is presently chaired by ANS Project Director C.D. West, was hosted by BemardFamoux (CEN) andChristian Desandre (Technicatome) at Saclay, France, last week. The worldwide group shares information on new and upgraded research reactor facilities.

ISSN:1044-8632    

DOI:10.1080/10448639208218766

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Brookhaven National Laboratory's High Flux Beam Reactor (HFBR) was built because the scientist always wants ‘more.’ In the mid-50's the Brookhaven Graphite reactor was churning away, producing anumber of new results, when the current generation of scientists, led by Donald Hughes, realized the need for a high flux reactor and started down the political, scientific and engineering path that led to the HFBR. The effort was joined by a number of engineers and scientists such as Chemick, Hastings, Kouts, and Hendrie that came up with the novel design of the HFBR. The two innovative features that have been incorporated in nearly all other research reactors built since are: (i) an undermoderated core arrangement which enables the thermal flux to peak outside the core region where beam tubes can be placed, and (ii) beam tubes that are tangential to the core which decrease the fast neutron background without affecting the thermal beam intensity. Construction began in the fall of 1961 and four years later, at a cost of $12 Million, criticality was achieved on Halloween Night, October 31, 1965. Thus began 25 years of scientific accomplishments.

ISSN:1044-8632    

DOI:10.1080/10448639208218767

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Welding or other non uniform heat treatments, and plastic deformation during fabrication, can leave strong residual stresses locked-up within components. These stresses can affect the component life in service as they may add to applied loads causing fatigue and failure. Consequently engineers have to allow for their presence, and they have sought for many years an absolute, nondestructive means of measurement of the internal residual stress fields within weldments and fabricated components. The engineer dreams of obtaining a simple small ‘black-box’ with a probe which could be placed on the surface of the component. On dialling the depth and direction of required stress, its value would be read off on a display! Unfortunately this ideal is still some way off full realisation, although a wide range of techniques exist to give limited information on the stress field (1). The engineer also has recourse to computer calculations of stress fields using finite element methods, or analytical models.

ISSN:1044-8632    

DOI:10.1080/10448639208218768

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Neutron topography is an imaging technique which maps the variations of the reflecting power. It has to bedistinguished from neutron radiography (l), which uses the differences in absorption. The topographic techniques (2) were developed in the late fifties and in the sixties, in the X-ray case, mainly to characterize the new crystals produced for the electronics industry, by visualizing the defects (dislocations, twins, precipitates—) present within their volume. They are non destructive and sensitive to very weak distortions(10−7is sometimes observable). Neutron topography started later, in the early seventies (3,4,5), and developed mainly at the high flux reactor of the Institute Laue Langevin. Reviews of the activity in neutron topography are given in references (6) and (7).

ISSN:1044-8632    

DOI:10.1080/10448639208218769

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The application of thermal neutron scattering to the study of the structure and dynamics of condensed matter requires a knowledge of the scattering lengths and the corresponding scattering and absorption cross sections of the elements. Ln some cases, values for the individual isotopes are needed as well. This information is required to obtain an absolute normalization ofthe scatteredneutron distributions, tocalculate unit-cell structure factors in neutron crystallography, and to correct for effects such as absorption, self-shielding, extinction, multiple scattering, incoherent scattering, and detector efficiency.

ISSN:1044-8632    

DOI:10.1080/10448639208218770

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:1044-8632    

DOI:10.1080/10448639208218771

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor