ISSN:0031-9228    

DOI:10.1063/1.3069042

出版商:AIP    

年代:1975

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3069044

出版商:AIP    

年代:1975

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3069046

出版商:AIP    

年代:1975

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3069047

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

New areas of interest may be opening for ultrashort, or picosecond duration, laser pulses. These pulses have already been used for many years in research ranging from molecular lifetime studies to nonlinear optics (seePHYSICS TODAY, July 1971, page 19). Recent applications to biophysics, condensed matter and plasma physics are reviewed in the article that begins on page 30 of this issue. One new area, recently reported by David H. Auston of Bell Labs,1is the application of these optical pulses to electronic switching functions; they can switch a signal in about 10 picoseconds, one or two orders of magnitude faster than semiconductor junction devices. A second area is the development of ultrafast pulses from the highly efficient carbon dioxide laser, thus extending the ultrafast pulses from the visible and near infrared, where they are currently available, toward the far infrared. Most recently at the Conference on Laser Engineering and Applications in Washington, DC from 28–30 May, one group announced a technique for fast optical switching of pulses from a carbon‐dioxide laser.

ISSN:0031-9228    

DOI:10.1063/1.3069049

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Laser separation has for the first time produced macroscopic amounts of isotopically enriched compounds of such elements as boron, chlorine and sulfur. Last fall experimenters at the Institute for Spectroscopy, Moscow1and the National Bureau of Standards2both described experiments on boron isotope separation from boron trichloride. An NBS group has also done work on separating chlorine isotopes. This past March the Moscow group reported their recent successes with sulfur. Shortly thereafter the Los Alamos Scientific Laboratory made public similar sulfur experiments. Results at all three places indicate that significant progress has been made since we last reported on laser isotope separation (PHYSICS TODAY, September 1974, page 17).

ISSN:0031-9228    

DOI:10.1063/1.3069050

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Nowadays there is a tendency among historians and social scientists to think of the postwar scientists' movement as a quaint aberration, and to dismiss the ideas we developed in the late 1940's as politically naive or irrelevant. Some go even further and would have us believe that time has shown the wisdom of those politicians who insisted on the need for maintaining American preeminence in nuclear armaments, despite our urgent warnings that this was a futile and dangerous course. As evidence, they cite the facts that for thirty years nuclear war has been averted, in spite of recurrent international crises, and that the number of nuclear‐weapons states has remained much smaller than the number that we predicted would be able to produce nuclear weapons on a time scale of thirty years.

ISSN:0031-9228    

DOI:10.1063/1.3069051

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Physicists and chemists have gained an impressive amount of new information on rapid phenomena in materials by using sophisticated new techniques for handling picosecond light pulses. The reason for the great growth of interest is not solely the development of new techniques for probing this time region, but also its importance for understanding the most fundamental processes in materials physics and chemistry. Since particle‐collision rates within materials are rapid, the picosecond time scale is the appropriate gauge for a larger number of energy‐transfer processes in substances.

ISSN:0031-9228    

DOI:10.1063/1.3069052

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

On 28 April at the Washington meeting of The American Physical Society, the results of a year‐long study of light‐water‐reactor safety were released. The study group, consisting of a dozen physicists, chemists and engineers, was chaired by Harold W. Lewis of the University of California at Santa Barbara; it reported to the Physical Society Council through a Steering–Review Committee consisting of Wolfgang K. H. Panofsky (chairman), Hans A. Bethe, and Victor F. Weisskopf. The study was jointly financed by the former Atomic Energy Commission and the National Science Foundation.

ISSN:0031-9228    

DOI:10.1063/1.3069053

出版商:AIP    

年代:1975

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3069054

出版商:AIP    

年代:1975

数据来源: AIP