| 释义 |
ˌultraˈcold, n. and a.
[f. ultra- 3 + cold a., n.]
A. n. Extreme coldness.
1967Britannica Bk. of Year (U.S.) 804/3 Ultracold, excessive coldness especially near absolute zero. 1977A. Hallam Planet Earth 15/1 The Moon's atmosphere..provides little protection from the direct heat of the Sun, and little insulation from the ultracold of space.
B. adj. Nucl. Physics. Of a neutron: having an energy of the order of 10-7 eV or less.
1969JETP Lett. IX. 26 Ultracold neutrons are produced and propagate in accordance with the theoretical expectations. 1978Nature 9 Mar. 127/1 Ultracold neutrons are slow neutrons with velocities of less than 7 m s-1. 1979Sci. Amer. June 106/1 A striking property of ultracold neutrons is their total reflection from solid surfaces. |