CH110 Study Guide - Final Guide: Wavelength, Population Inversion, Acoustic Wave
This seeming contradiction can be resolved if
account is taken of wave properties of the
neutrons, which is supported by the fact that the
resonance cross section depends upon the neutron
wave length [13]. The target nucleus deflects the
neutronic wave and gathers it into a narrow beam
that
penetrates the nucleus, the deflection being
extended over enormous distances.
Thus we can see that a resonator is able to suck in
the incident wave from a tremendous region of
space, redistributing energy flows and so
accumulating energy. This can be attributed to the
presence of positive feedback in the system made
up of the resonator and the incident wave. Since
the wave contracts into a narrow beam, the
amplitude of the wave should
grow considerably in the neighbourhood of the
resonator.
When deducing (4.2), it is assumed that the
resonator has no effect on the perturbation as
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long as the perturbation is fixed. However, under
these conditions too, the capability of the
resonator for accumulating energy manifests itself.
The time it takes for the resonator to absorb an
energy packet of En − Em when |an| = 1 in (4.2) is t
= π/(2|η|). The weakness of the perturbation (the
smallness of |η|) affects only the time necessary to
accumulate the energy. When the resonator can
redistribute energy flows by feedback as is the real
situation with the 54Xe135 nuclei, the time taken to
accumulate the energy should decrease
appreciably.
The above properties of resonators are familiar in
acoustics. The amplitude of vibration in the hole
of an acoustic resonator is many times greater than
the amplitude of the acoustic field the resonator is
placed in [18], which suggests essential
redistribution of the incident acoustic wave and
sucking the wave by the resonator because the
latter amplifies sound using the energy of the
incident wave alone. It is interesting that the
wavelength relevant to low- frequency modes of
Helmholtz’s resonator far exceeds the size of the
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Document Summary
This seeming contradiction can be resolved if account is taken of wave properties of the neutrons, which is supported by the fact that the resonance cross section depends upon the neutron wave length [13]. The target nucleus deflects the neutronic wave and gathers it into a narrow beam that penetrates the nucleus, the deflection being extended over enormous distances. Thus we can see that a resonator is able to suck in the incident wave from a tremendous region of space, redistributing energy flows and so accumulating energy. This can be attributed to the presence of positive feedback in the system made up of the resonator and the incident wave. Since the wave contracts into a narrow beam, the amplitude of the wave should grow considerably in the neighbourhood of the resonator. When deducing (4. 2), it is assumed that the resonator has no effect on the perturbation as long as the perturbation is fixed.
