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21.
Die Anwendung radioaktiver Nuklide in der chemischen Industrie kann nach der jeweils verwendeten Eigenschaft des strahlenden Materials in drei Gruppen eingeordnet werden 相似文献
22.
We discuss the conditions required for an optimal SASE FEL operation when bunch compression techniques are exploited to enhance the bunch peak current. We discuss the case of velocity bunching and magnetic bunch compression. With reference to the latter technique we provide a quantitative estimate of the amount of laser heater power necessary to suppress the micro-bunching instability without creating any problem to the SASE dynamics. 相似文献
23.
Im ersten Teil der Arbeit wurde über den Ausbau eines Van-de-Graaff-Generators zum Röntgenstrahlungserzeuger für die Standarddosimetrie berichtet. Der vorliegende zweite Teil behandelt den Aufbau und die Wirkungsweise einer Magnetfeld-Druck-Ionisationskammer, die die Darstellung der Einheit Exposition im Energieintervall von 0,6 MeV bis 1,8 MeV für Röntgenbremsstrahlung mit einer Meβsicherheit von 2% gewährleistet. Die Normalkammer ist fūr Messungen bei erhöhtem Luftdruck bis 10 kp/cm2 konzipiert. Das Magnetfeld zur Verrigerung ihrer Querabmessungen wird durch eine endkorrigierte Zylinderspule erzeugt, die das zylindrische Druckgefäβ aus nichtferromagetischem Stahl umschlieβt. Die eigentliche Ionisationskammer hat die Form einer Zylinderschalenkammer. Die Untersuchungen zur Bestimmung der Bertiebsparameter der Kammer werden dargestellt. Auβerdem wird auf die in die Bestimmungsgleichung fūr die Exposition eingehenden Korrektionsfaktoren kurz eingegangen. 相似文献
24.
Robert P. Crease 《Physics in Perspective (PIP)》2009,11(1):15-45
This is the second part of a two-part article about the National Synchrotron Light Source (NSLS), the first facility designed
and built specifically for producing and exploiting synchrotron radiation. The NSLS,a $24-million project conceived about
1970 and officially proposed in 1976, had its groundbreaking in 1978. Its construction was a key episode in Brookhaven’s history,
in the transition of synchrotron radiation from a novelty to a commodity, and in the transition of synchrotron-radiation scientists
from parasitic to autonomous researchers. In this part I cover the construction of the NSLS.The story of its construction
illustrates many of the tensions and risks involved in building a large scientific facility in a highly politicized environment:
risking a facility’s quality by underfunding it versus asking for more funding and risking not getting it; focusing on meeting time and budget promises that risk compromising machine
performance versus focusing on performance and risking cancellation; and the pros and cons of a pragmatic versus an analytic approach to commissioning.
Robert P. Crease is a Professor in the Department of Philosophy of Stony Brook University in Stony Brook, New York, and historian
at Brookhaven National Laboratory. 相似文献
25.
Robert P. Crease 《Physics in Perspective (PIP)》2008,10(4):438-467
The National Synchrotron Light Source (NSLS) was the first facility designed and built specifically for producing and exploiting
synchrotron radiation. It was also the first facility to incorporate the Chasman-Green lattice for maximizing brightness.
The NSLS was a $24-million project conceived about 1970. It was officially proposed in 1976, and its groundbreaking took place
in 1978. Its construction was a key episode in Brookhaven’s history, in the transition of synchrotron radiation from a novelty
to a commodity, and in the transition of synchrotron-radiation scientists from parasitic to autonomous researchers. The way
the machine was conceived, designed, promoted, and constructed illustrates much both about the tensions and tradeoffs faced
by large scientific projects in the age of big science. In this article, the first of two parts, I cover the conception, design,
and planning of the NSLS up to its groundbreaking. Part II, covering its construction, will appear in the next issue.
Robert P. Crease is a Professor in the Department of Philosophy of Stony Brook University in Stony Brook, New York, and historian
at Brookhaven National Laboratory. 相似文献
26.
D. Guerreau 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):263-266
During the last ten years, the cooperation in Nuclear Physics between the different European countries has significantly increased,
in particular through extensive discussions initiated by NuPECC, the Nuclear Physics European Collaboration Committee. In
this context, perspectives in physics with radioactive beams have been reviewed and a high priority has been given to the
developments of performing facilities in Europe including both in-flight and ISOL facilities. In this presentation, the main
challenges are recalled and the various existing national and transnational projects are reviewed as well as the accompanying
research and development programs. A special attention is given to the EURISOL project, a European program aiming at a preliminary
design study of a second-generation European ISOL radioactive beam facility.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
27.
Effects of sulphate,calcium and aluminum ions upon the hydration of sulphoaluminate belite cement 总被引:2,自引:0,他引:2
In the model sulphoaluminate belite cement, the process of hydration is governed by the diffusion and transport phenomena of the main ionic species. The sulphate components and combined sulphate and aluminium ions, exert an accelerating effect upon the kinetics of sulphoaluminate belite cement hydration. Aluminium and calcium ions delay the hydration by creating a retarding layer which can be considered a co-precipitate of aluminium and calcium hydroxides. This is revealed in the calorimetric curves by the duration of induction period and also by the intensities of the main peaks. The appearance of small additional peaks characterizes the formation of primary ettringite, due to the presence of sulphate ions in aqueous solution. The intensities of these peaks depend on the ion concentration too. 相似文献
28.
29.
Kenneth P. Felis Tovi Avnery Anthony J. Berejka 《Radiation Physics and Chemistry》2002,63(3-6):605-608
Advanced electron beams (AEB) has developed a modular, low voltage (80–125 keV), high beam current (up to 40 ma), electron emitter with typically 25 cm of beam width, that is housed in an evacuated, returnable chamber that is easy to plug in and connect. The latest in nanofabrication enables AEB to use an ultra-thin beam window. The power supply for AEB's emitter is based on solid-state electronics. This combination of features results in a remarkable electrical efficiency. AEB's electron emitter relies on a touch screen, computer control system. With 80 μm of unit density beam penetration, AEB's electron emitter has gained market acceptance in the curing of opaque, pigmented inks and coatings used on flexible substrates, metals and fiber composites and in the curing of adhesives in foil based laminates. 相似文献
30.
G. Maero P. Quarati F. Ferro 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):23-26
An interest for the low-energy range of the nonextensive distribution function arises from the study of radiative recombination
in electron cooling devices in particle accelerators, whose experimentally measured reaction rates are much above the theoretical
prediction. The use of generalized distributions, that differ from the Maxwellian in the low energy part (due to subdiffusion
between electron and ion bunches), may account for the observed rate enhancement. In this work, we consider the isotropic
distribution function and we propose a possible experiment for verifying the existence of a cut-off in the generalized momentum
distribution, by measuring the spectrum of the X-rays emitted from radiative recombination reactions. 相似文献