| 释义 |
yrast, a. Nucl. Physics.|ˈɪræst|
[See quot. 1967.]
Pertaining to or designating any nuclear energy level that is the lowest for some value of the spin; yrast line, a line on a graph of spin against nuclear rotational energy (or some function of each of these), connecting points representing the various yrast states of a nuclide.
1967J. B. Grover in Physical Rev. CLVII. 832 It has been proposed that the lowest-energy excited state at a given angular momentum be called ‘yrast’ level for that angular momentum. Ibid. 832/1 The yrast levels play a crucial role in deciding the course and outcome of many nuclear reactions. [Note] By ‘yrast’ level of a given nucleus, at a given angular momentum, is meant the level with least energy at that angular momentum. The English language seems not to have a graceful superlative form for adjectives expressing rotation. Professor F. Ruplin (of the Germanic Languages Department of the State University of New York, Stony Brook) suggested the use of the Swedish adjective yr for designating these special levels. This word derives from the same Old Norse verb hvirfla (to whirl) as the English verb whirl, and forms the natural superlative, yrast. It can thus be understood to mean ‘whirlingest’, although literally translated from Swedish it means ‘dizziest’ or ‘most bewildered’. 1971Physics Lett. XXXIVb. 575 Non⁓axially symmetric deformation of a nucleus is introduced to account for the admixture of the collective rotational bands and the distribution of the yrast levels. 1974Frauenfelder & Henley Subatomic Physics xvi. 435 The yrast line of a nucleus gives E as a function of J. 1983Nucl. Physics A. CDIII. 421 Precession of the yrast 2+1 , and 4+1 , and the second 2+2 states in 24Mg have been measured. |