ISSN:0031-9228    

DOI:10.1063/1.3128622

出版商:AIP    

年代:1974

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3128624

出版商:AIP    

年代:1974

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3128626

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

A recent theoretical calculation of neutrino–nucleon cross sections, based on neutral currents, has revived interest in a model that proposes neutrino interactions as the mechanism for explosions in supernovae. The neutrino idea was first suggested by Stirling Colgate of the New Mexico Institute of Mining and Technology and Richard White of the Lawrence Livermore Laboratory. Subsequent calculations were performed by W. David Arnett of the University of Texas and by L. N. Ivanova, V. S. Inshennik and D. K. Nadezhin at the Institute of Applied Mathematics of the USSR Academy of Sciences. A more refined calculation by James R. Wilson (Lawrence Livermore Laboratory) showed that the neutrino interaction then assumed (from the theory by Richard Feynman and Murray Gell‐Mann) was of the wrong form to account for explosions. Now Daniel Z. Freedman of the National Accelerator Laboratory has found that if neutral currents exist, the scattering of neutrinos by nuclei is coherent; thus the cross sections go as the square of the atomic weight. Wilson has redone his earlier calculations with the new cross sections and has found that they can account for explosions, depending on what values are assumed for the neutral‐current coupling constant and for the muon–neutrino opacity.

ISSN:0031-9228    

DOI:10.1063/1.3128628

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

In his recent measurements of the electrical conductivity of plastically deformed cadmium sulfide, Charles Elbaum of Brown University has found a large anistropy and unusual temperature dependence over a range from 20 to 300 K. The conductivity in the direction of the longest(z)axis of his specimens is from106to108 timesthat along the other two mutually perpendicular directions. As a function of temperature the conductivity along thezaxis first rises to a maximum of about4.5 (&OHgr; cm)−1near 125 K, then decreases exponentially. By contrast, the conductivities at right angles decrease monotonically from values of about10−6 (&OHgr; cm)−1at 300 K to values of about10−8 (&OHgr; cm)−1at 125 K. Elbaum feels that the experimental results imply a metallic‐type conduction along a pseudo‐one‐dimensional system consisting of arrays of dislocations.

ISSN:0031-9228    

DOI:10.1063/1.3128629

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The Swiss Institute for Nuclear Research (SIN) has announced the production of a 590‐MeV proton beam from its cyclotron at Villigen. The SIN cyclotron system, composed of two cyclotrons, later produced pions from a thin target. Muon production and polarized‐proton beams are anticipated for later this year as experimentation gets underway.

ISSN:0031-9228    

DOI:10.1063/1.3128630

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Initial funding for a large tandem electrostatic accelerator at Oak Ridge appears in the FY 1975 AEC budget request. Also included in the $19.2‐million request is money for expansion and upgrading of SuperHILACat Lawrence Berkeley Laboratory.

ISSN:0031-9228    

DOI:10.1063/1.3128631

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

The idea that the public, as well as the government and industry, should have scientific advisors is an old one. The idea that the interests of the public should have lawyers to defend them is old too, yet it was not until the 1960's that a renewed public understanding of the insensitivity of governmental and industrial bureaucracies led to a substantial commitment in the legal profession to public‐interest law. It appears that the scientific community may now have reached a similar point; a growing awareness of the dangers of leaving the exploitation of technology to special industrial and governmental interests has led to an increased readiness among scientists to undertake work in public‐interest science.

ISSN:0031-9228    

DOI:10.1063/1.3128632

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Almost all decisions that affect significant portions of society—whether or not to develop solar energy, to build a local highway or to develop a new poptop beverage container—are basically political rather than scientific. Nevertheless, technical input can be decisive.

ISSN:0031-9228    

DOI:10.1063/1.3128633

出版商:AIP    

年代:1974

数据来源: AIP

摘要:

Science and technology resulting from applications of scientific knowledge require a great deal of legislative attention. Some of the reasons for this are obvious. Readers ofPHYSICS TODAYare probably aware of the Atomic Energy Act of 1954, the National Science Foundation Act of 1950 and the National Aeronautical and Space Administration Act of 1958. These laws, currently on the statute books, deal explicitly with science and technology.

ISSN:0031-9228    

DOI:10.1063/1.3128634

出版商:AIP    

年代:1974

数据来源: AIP