ISSN:1044-8632    

DOI:10.1080/10448639308218925

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

There is a debate going on about theraison d'etreof large-scale central facilities. They serve a multiple role and attract an increasing number of scientists, wheth & for a single specific experiment or as part of a long term research program. The current financial and political climate is not a favorable one for large scale investment and this naturally reflects on neutron scattering facilities. Hard-won expensive capital equipment can not be utilized to its full effectiveness because of reducing resources of both manpower and money. From the shop-floor of scientific endeavor this appears to be a result of appallingly short-sighted and arbitrary policies. Accordingly, the demand for beam time from the user community far out-strips the supply, a situation which is aggravated by the shut-down of ILL and the KFA reactor at Julich. Despite that, there is a surprisingly large amount of activity going on in the field of quasielastic neutron scattering (QENS).

ISSN:1044-8632    

DOI:10.1080/10448639308218926

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

This workshop, held September 15–18, 1992 in Giardini Naxos (Italy), was the 7th Topical Meeting of the Liquids Section from the Condensed Matter Division of the European Physical Society. The Directors were J. Teixeira (Laboratoire Léon-Brillouin, Saclay, France), A.J. Dianoux (Institut Laue-Langevin, Grenoble, France) and F. Wanderlingh (University of Messina, Italy). The Organizing Committee was composed of R. Giordano (University of Messina, Italy) and J.C. Leickmann (University Paris VI, France).

ISSN:1044-8632    

DOI:10.1080/10448639308218928

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The neutron scattering activity in condensed matter in Italy started in the late 1950s in a close collaboration with the most important' laboratories in the United States (one can not forget the work of Fermi's group in Rome in 1930, but this activity is a well-known story). The experience gained from this collaboration was used in Italy, where two facilities were built. The two facilities were located first in Ispra, near Turin, which was part of a EURATOM center, and second in the Casaccia center close to Rome, which belonged to the National Atomic Energy Commission. A third facility, located in Pisa and belonging to the Defense Ministry was also used for some time in the period from 1970–1975. In all cases, the research activity during the two decades of the '60s and '70s was mainly devoted to condensed matter physics and involved a rather large number of scientists at the level of the most developed countries. One can mention that the first polarized neutron diffractometer and the first triple-axis spectrometer in Europe were installed in Casaccia and in Ispra, respectively. To appreciate the situation during this period, one can look at Figure 1, where the number of publications per year is reported.

ISSN:1044-8632    

DOI:10.1080/10448639308218929

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Neutron depth profiling (NDP) is a nondestructive technique for the measurement of isotopic concentrations as a function of depth. Using neutrons to probe the first few micrometers of solid surfaces, NDP has become an important tool in the nondestructive analyses for several technologically important elements. The National Institute of Standards and Technology (NIST) has operated a dedicated NDP facility (I) since 1982 using thermal neutrons. Recently, a second, more versatile instrument (2) with improved detection limits was installed as part of the Cold Neutron Research Facility (CNRF) at NIST.

ISSN:1044-8632    

DOI:10.1080/10448639308218930

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

It has been of interest for a number of years to ask whether one can use the neutron-electron scattering cross-section as a probe of the superconducting phase transition in a manner analogous to that employed so successfully in magnetic metals (1,2). Such an approach may yield dynamic microscopic detail critical in shaping our picture of the superconducting state. As in the case of magnetic metals, which may be most readily understood in the regime where they are strongly exchange enhanced but still retain the symmetry of the normal paramagnetic ground state, we focus attention on scattering cross-section in the normal phase just above the superconducting transition. Until recently, the relatively low temperatures and long length scales involved in the phenomena of superconductivity reduced the possibilities of observation of neutron scattering frolh enhance conductivity fluctuations to the marginal level. Little effort appears to have been expended in this direction. We were stimulated to attempt such experiments early in 1987 by the discovery of the “Hi-Tc” superconducting ceramics for which the high transition temperatures enable significant thermal population to be put into low energy excitations and, second, the contracted spatial scale of pairing, more or less implied by the high transition temperatures and, hence, the inferred effective binding energy which allows measurements to be performed at experimentally accessible scattering angles.

ISSN:1044-8632    

DOI:10.1080/10448639308218931

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

ISSN:1044-8632    

DOI:10.1080/10448639308218932

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Fundamental Properties of the Neutron, Yu. A. Alexandrov, 1992, Oxford Science Publishers, Oxford Publications Series on Neutron Scattering in Condensed Matter-6

ISSN:1044-8632    

DOI:10.1080/10448639308218933

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor