ISSN:0031-9228    

DOI:10.1063/1.3129024

出版商:AIP    

年代:1974

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3129025

出版商:AIP    

年代:1974

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3129027

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Nuclear scientists studying the reactions induced by heavy ions have encountered an unexpected process that has been variously dubbed “quasifission,” “deep inelastic transfer,” “relaxed‐peak process,” “incomplete fusion” and “strongly damped collisions.” In this process the reaction products have the kinetic energies typical of fission products, but their masses differ from what one would expect in fission: In the latter process, each of the reaction products has a mass roughly equal to one‐half of the total mass of the compound nucleus (target plus projectile). In quasifission the two product nuclei have masses close to those of the target and projectile, individually.

ISSN:0031-9228    

DOI:10.1063/1.3129029

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Optical astronomers are frequently hampered by atmospheric turbulence that distorts telescopic images by causing random phase shifts in the incoming light. These distortions often reduce the resolution of a telescope far below its diffraction limit. But the outlook may be brightened by new techniques now being developed to detect and correct for the phase error in real time. Until now most techniques to correct for atmospheric distortions have been post‐detection compensation techniques: The effects of turbulence are extracted after the image data has been recorded. Three of the groups that are conducting major development efforts on real‐time compensation described their work at a conference on Optical Propagation Through Turbulence that was sponsored by the Optical Society of America at the University of Colorado, 9–11 July. These three groups are from Hughes Research Laboratories, from Itek Corporation and from Lawrence Berkeley Laboratory and the Institute for Advanced Studies.

ISSN:0031-9228    

DOI:10.1063/1.3129030

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A negative ion source that can provide high yields of nearly all known stable negative ions and enables the user to vary the ion species within minutes has been developed by Roy Middleton and Charles T. Adams of the University of Pennsylvania, Philadelphia. The negative ions are formed directly from a solid surface by the sputter action of 30‐keV positive cesium ions resulting in a negative ion current of the order of 10 microamps. A unique feature here is that a simple, long‐lived surface ionization source (similar to a type used in thrusters for space satellites) produces the cesium ion beam, rather than the duoplasmatron conventionally used in negative‐ion sources, eliminating the problems caused by the presence of plasmas and gases. This new source, developed at the Penn Tandem Accelerator Laboratory, is particularly applicable to Tandem Van de Graaff accelerators, which must use negative ions and have, until now, been unable to live up to their full potential as universal accelerators of all varieties of ions. High‐energy linear accelerators, as well as atomic‐beam experiments, could also incorporate these sources.

ISSN:0031-9228    

DOI:10.1063/1.3129031

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The world has changed since 1899, but there are few fields that have changed more—in the development of fundamental insights and in the discovery of new phenomena—than astronomy. When we glance at the titles (see the box below) of some of the recent papers published, for example, in theAstrophysical JournalandIcarus, we can only conclude that our astronomical ancestors would have extracted a glimmer of meaning from them, but that the principal reaction would have been incredulity.

ISSN:0031-9228    

DOI:10.1063/1.3129032

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

During 1974 the American Astronomical Society is celebrating the 75th anniversary of its founding. To be precise historically, however, there are at least two problems with such a commemoration. First, when the association was founded in 1899, its name was not “The American Astronomical Society,” and second, another association with precisely that name had nominally been founded at least fifteen years earlier!

ISSN:0031-9228    

DOI:10.1063/1.3129033

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

What is behind the unusual flurry of activity concerned with the isotope deuterium? Simply this: Because of its unique properties, the distribution of deuterium in the universe constitutes a powerful clue to the history of the development of matter.

ISSN:0031-9228    

DOI:10.1063/1.3129034

出版商:AIP    

年代:1974

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3129035

出版商:AIP    

年代:1974

数据来源: AIP