ISSN:0031-9228    

DOI:10.1063/1.2408437

出版商:AIP    

年代:1902

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.1457250

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Collisions make chemical reactions possible. Scattering collisions kick reactants into excited states; reactive collisions finish the job. Understanding these collisions—being able to predict and control them—is one of physical chemistry's ultimate prizes. With it would come not just the satisfaction of explaining chemical reactions from quantum fundamentals, but also the ability to steer such industrially important reactions as combustion.

ISSN:0031-9228    

DOI:10.1063/1.1457251

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Louis de Broglie's 1923 proposal that particles could display wave behavior paved the way to modern quantum mechanics. Within five years, Clinton Davisson and Lester Germer in the US, and George Thomson in Scotland, confirmed de Broglie's proposal by diffracting electrons off crystals. In 1933, Peter Kapitza and Paul Dirac proposed that a grating of standing waves of light could also diffract electrons: The diffraction peak separation would be proportional to the de Broglie wavelength of the electrons and inversely proportional to the wavelength of the light making the standing waves.

ISSN:0031-9228    

DOI:10.1063/1.1457252

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

The workers below are lowering one of three new superconducting bending magnets into the beamline at Lawrence Berkeley National Laboratory's Advanced Light Source this past August. These new magnets have added hard x rays to the accelerator's offerings of synchrotron radiation beams. The demand for such x‐ray sources has grown explosively in recent years, thanks primarily to work on protein crystallography.

ISSN:0031-9228    

DOI:10.1063/1.1457253

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

When the World Trade Center towers collapsed into a nightmarish pile of burning rubble after being struck by two airliners on 11 September, one of the many emergency units that rushed to the site was a radiation monitoring team based at Brook‐haven National Laboratory. As firefighters, police, and medical personnel frantically searched for survivors, concerns arose about possible radiation dangers from industrial x‐ray machines and other radiological sources believed to have been in the buildings.

ISSN:0031-9228    

DOI:10.1063/1.1457254

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

While the tank was being refilled with 50 000 tons of water, a photomultiplier tube imploded and the shock wave set off a chain reaction that left more than 7000 PMTs shattered. That, at least, is what scientists surmise happened on the morning of 12 November in Super‐Kamiokande, the world's largest neutrino detector.

ISSN:0031-9228    

DOI:10.1063/1.1457255

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Just days after Dan Goldin announced he was leaving his post as NASA administrator (see PHYSICSTODAYDecember 2001, page 22), President Bush surprised the science community by naming Sean O'Keefe, a nonscientist, for the job. The 45‐year‐old O'Keefe comes to NASA from his position as deputy director at the White House Office of Management and Budget (OMB). The nomination came on 14 November, after an 11‐month search for Goldin's replacement. “Everyone at NASA feels better now that someone has been named,” says Ed Weiler, NASA's associate administrator for space science. “It's not good for morale, having a long time without an announcement about a successor.”

ISSN:0031-9228    

DOI:10.1063/1.1457257

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

When Norman Neureiter was appointed as the first science and technology adviser to the Secretary of State in the waning days of the Clinton administration, his first priorities were to make State Department employees aware of the value of science in international relations and to convince scientists that they could contribute to the work of diplomats. Nearly 16 months later, Neureiter has two veteran scientists working on year‐long fellowships in the department, a separate program that sends scientists on brief stints to embassies around the globe, and foreign service officers in 40 embassies saying they would like scientific help.

ISSN:0031-9228    

DOI:10.1063/1.1457258

出版商:AIP    

年代:1902

数据来源: AIP

摘要:

Caltech's coffers are $600 million richer, thanks to semiconductor pioneer Gordon Moore, his wife Betty, and the foundation the couple created in 2000. Their combined gift—$300 million from the Moores and the same again from the Gordon and Betty Moore Foundation—is the largest‐ever donation to a university, eclipsing last year's record‐breaking gifts of $400 million to Stanford University from the William and Flora Hewlett Foundation and an anonymous $360 million to Rensselaer Polytechnic Institute.

ISSN:0031-9228    

DOI:10.1063/1.1457260

出版商:AIP    

年代:1902

数据来源: AIP