905 research outputs found
Classicalization of Quantum Fluctuation in Inflationary Universe
We discuss the classicalization of a quantum state induced by an environment
in the inflationary stage of the universe. The classicalization is necessary
for the homogeneous ground sate to become classical non-homogeneous one
accompanied with the statistical fluctuation, which is a plausible candidate
for the seeds of structure formation. Using simple models, we show that i) the
two classicalization criteria, the classical correlation and quantum
decoherence, are simultaneously satisfied by the environment and that ii) the
power spectrum of the resultant statistical fluctuation depends upon the detail
of the classicalization process. Especially, the result ii) means that, taking
account of the classicalization process, the inflationary scenario does not
necessarily predict the unique spectrum which is usually believed.Comment: 24 pages, Latex, 2 Postscript figure
Feedback-free optical cavity with self-resonating mechanism
We demonstrated the operation of a high finesse optical cavity without
utilizing an active feedback system to stabilize the resonance. The effective
finesse, which is a finesse including the overall system performance, of the
cavity was measured to be , and the laser power stored in
the cavity was kW, which is approximately 187,000 times greater
than the incident power to the cavity. The stored power was stabilized with a
fluctuation of , and we confirmed continuous cavity operation for more
than two hours. This result has the potential to trigger an innovative
evolution for applications that use optical resonant cavities such as compact
photon sources with laser-Compton scattering or cavity enhanced absorption
spectroscopy.Comment: 5 pages, 7 figure
Development of an intense positron source using a crystal--amorphous hybrid target for linear colliders
In a conventional positron source driven by a few GeV electron beam, a high
amount of heat is loaded into a positron converter target to generate intense
positrons required by linear colliders, and which would eventually damage the
converter target. A hybrid target, composed of a single crystal target as a
radiator of intense gamma--rays, and an amorphous converter target placed
downstream of the crystal, was proposed as a scheme which could overcome the
problem.This paper describes the development of an intense positron source with
the hybrid target. A series of experiments on positron generation with the
hybrid target has been carried out with a 8--GeV electron beam at the KEKB
linac. We observed that positron yield from the hybrid target increased when
the incident electron beam was aligned to the crystal axis and exceeded the one
from the conventional target with the converter target of the same thickness,
when its thickness is less than about 2 radiation length. The measurements in
the temperature rise of the amorphous converter target was successfully carried
out by use of thermocouples. These results lead to establishment to the
evaluation of the hybrid target as an intense positron source.Comment: 17pages, 10figure
Plasma-quenching Efficiency of CO2 by Estimation of C2 Rotational and Vibrational Temperatures in High-pressure High-power Ar-CO2 Induction Plasmas
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