Anniversary paper. Development of x-ray computed tomography: the role of medical physics and AAPM from the 1970s to present.
(9/23)
The AAPM, through its members, meetings, and its flagship journal Medical Physics, has played an important role in the development and growth of x-ray tomography in the last 50 years. From a spate of early articles in the 1970s characterizing the first commercial computed tomography (CT) scanners through the "slice wars" of the 1990s and 2000s, the history of CT and related techniques such as tomosynthesis can readily be traced through the pages of Medical Physics and the annals of the AAPM and RSNA/AAPM Annual Meetings. In this article, the authors intend to give a brief review of the role of Medical Physics and the AAPM in CT and tomosynthesis imaging over the last few decades. (+info)
Discovery of naked charm particles and lifetime differences among charm species using nuclear emulsion techniques innovated in Japan.
(10/23)
This is a historical review of the discovery of naked charm particles and lifetime differences among charm species. These discoveries in the field of cosmic-ray physics were made by the innovation of nuclear emulsion techniques in Japan. A pair of naked charm particles was discovered in 1971 in a cosmic-ray interaction, three years prior to the discovery of the hidden charm particle, J/Psi, in western countries. Lifetime differences between charged and neutral charm particles were pointed out in 1975, which were later re-confirmed by the collaborative Experiment E531 at Fermilab. Japanese physicists led by K.Niu made essential contributions to it with improved emulsion techniques, complemented by electronic detectors. This review also discusses the discovery of artificially produced naked charm particles by us in an accelerator experiment at Fermilab in 1975 and of multiple-pair productions of charm particles in a single interaction in 1987 by the collaborative Experiment WA75 at CERN. (+info)
The szilard hypothesis on the nature of aging revisited.
(11/23)
Medical use of byproduct material--authorized user clarification. Direct final rule.
(12/23)
The U.S. Nuclear Regulatory Commission (NRC) is amending its regulations to clarify that individuals who do not need to comply with the training and experience requirements as described in the applicable regulations for the medical use of byproduct material (i.e., are "grandfathered") may serve as preceptors and work experience supervisors for individuals seeking recognition on NRC licenses for the same medical uses of byproduct material. The regulations that govern the medical use of byproduct material were amended in their entirety in 2002 and again in 2005. Currently, individuals who were identified on an NRC or Agreement State license or permit before the regulations were amended do not need to requalify by meeting the training and experience (T&E) requirements of the applicable regulations. When the regulations were revised, the NRC intended that those authorized individuals would also be able to serve as preceptors and work experience supervisors. However, the regulations as they are currently written do not specifically state that grandfathered individuals can be work experience supervisors and preceptors. This direct final rule amends the regulations to clarify that all individuals grandfathered under the applicable regulations may serve as preceptors and work experience supervisors for individuals seeking recognition on an NRC license for the same uses. Additionally, several minor administrative changes are included in this rulemaking. (+info)
New way to produce dense double-antikaonic dibaryon system, KKNN, through Lambda(1405)-doorway sticking in p+p collisions.
(14/23)
A recent successful observation of a dense and deeply bound K nuclear system, K-pp, in the p+p-->K++K-pp reaction in a DISTO experiment indicates that the double-K dibaryon, K-K-pp, which was predicted to be a dense nuclear system, can also be formed in p+p collisions. We find theoretically that the K--K- repulsion plays no significant role in reducing the density and binding energy of K-K-pp and that, when two Lambda(1405) resonances are produced simultaneously in a short-range p+p collision, they act as doorways to copious formation of K-K-pp, if and only if K-K-pp is a dense object, as predicted. (+info)
Cross sections of the 36Ar(d,alpha)34mCl, 40Ar(d,alpha)38Cl, and 40Ar(d,p)41Ar nuclear reactions below 8.4 MeV.
(15/23)