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[en] Here is a review of the current way we handle source photons in Implicit Monte Carlo (IMC). A source photon is created with a randomly sampled position xp in the zone, a direction (Omega)p, a frequency vp sampled from the appropriate distribution, and a time tp uniformly sampled from (tn, tn+1). The source photons each have an energy Ep. The sum of Ep over all of the photons equals the energy of the source for that time step. In the case of thermal emission in a zone with Volume V, they would have Σp=1N Ep = σ pacT4VΔt, where N is the number of thermal source photons for that time step, and σp is the Planck mean opacity. Census photons do not differ from source photons in any way, except that they all start the time step with tp = tn. Then they advance each photon until it reaches the end of the time step. When they are done with all of the photons, they update the matter temperature using the difference between the emitted and absorbed energy, and proceed to the next time step.
[en] The transmission of 500 ns pulses through GaAs-AlGaAs heterostructures has been studied as a function of light intensity and wavelength. The intrinsic exciton absorption can be modeled by the sum of a small unsaturable background and a dominant term which saturates as a Bloch resonance. Corrections for the Gaussian transverse spatial profile and finite optical thickness lead to 150 W/cm2 for the uniform-plane-wave saturation intensity for an optically thin GaAs exciton transition. The nearly Bloch-like saturation curve does not imply that the free exciton transition is a simple saturable two-level system, but does suggest that it saturates as a homogeneously broadened line
[en] We report the experimental observation of an optically controllable shift of the central frequency of a laser pulse, using a scheme based on dynamical electromagnetically induced transparency. This is evidence of frequency shift controllable by a coherent process. Original theoretical results are in agreement with the experimental data.
[en] QIKMIX is a quick-turnaround computer code developed to compute the radiative Rosseland mean opacity of specified mixtures at specified temperature and density points. The QIKLIB data base, which QIKMIX uses, has been derived from the OPLIB library. For most mixtures, QIKMIX can compute opacities over a temperature range of 50 to 25,000 eV in less than 1 min of CDC 7600 computer time. The purpose of this report is to discuss the QIKLIB data base and the operation of the QIKMIX code
[en] In this work we report on the development of a new method for computing mi- and high-Z NLTE opacities. A study has been performed using this method to assess the EOS and opacity sensitivities to the radiation field for both single species Au and multi-species SnNb and U3Au plasma cocktails with an emphasis on moderately to highly ionized systems. Developed as a benchmark tool, this capability will be used to assess both current and future in-line NLTE opacity capabilities.
[en] While a criminal investigation and international inspection are similar in the purpose of identifying any possible violator, there are also differences between them. Especially in the case of a criminal procedure, the defendants are presumed to be innocent until he or she is convicted, but states must make efforts to prove their nuclear transparency. Let's compare both of them to find out the reason why these different points have happened
[en] We investigate the optical bistability and multistability behaviors in a four-level Λ-type system using a microwave field driving a hyperfine transition between two lower states inside a unidirectional ring cavity. By controlling the microwave field and the frequency detunings of the three fields, we find that the appearance and disappearance of OB (or OM) can easily be controlled by adjusting the positions of the dual-EIT windows. Our scheme may be used for building more efficient all-optical switches and logic-gate devices for optical computing and quantum information processing. - Highlights: ► Optical bistability and multistability via dual-EIT windows are investigated. ► The scheme shows some intrinsic characteristics that other schemes do not have. ► The appearance and disappearance of OB/OM can easily be controlled by adjusting the positions of dual-EIT windows.
[en] Status Update of the Precision Attenuation Length Measurement Setup The planned JUNO detector is a 20 kt liquid scintillator neutrino detector. Its primary goal is the determination of the neutrino mass hierarchy. This will be done by precision measurements of the reactor antineutrino survival probability. Due to the spherical detector's diameter of approx. 35.5 m, the optical parameters, especially the attenuation length, of the scintillator have to be known precisely and have to be very good to achieve the required energy resolution of 3% rate at 1MeV. To determine one of the crucial optical parameters, the attenuation length, a new spectrometer experiment, called PALM, was built. Unless the commercially available spectrometers with light paths up to 10 cm, this spectrometer is able to measure light paths up to 2.8 m through the medium, making it possible to determine the attenuation length very precisely. This talk gives a status update on the commissioned PALM setup.
[en] Photometry cell for measuring the optical density of fluids and particularly the turbidity of river or nuclear reactor waters or also for detecting pollutants in liquids or gases. The instrument enables the optical path to be extended, and hence the accuracy, by multiple reflexions on spherical mirrors and an optical system operating by transmission. The facilities used to introduce and extract the light beam can be constituted by light guides, particularly optical fibres
[fr]Cellule de photometrie pour la mesure de la densite optique de fluides et notamment pour la mesure de la turbidite des eaux de riviere ou de reacteurs nucleaires, ou encore pour la detection de polluants dans les liquides ou les gaz. Le dispositif permet d'allonger le parcours optique, et donc la precision, par reflexions multiples sur des miroirs spheriques et une optique travaillant en transmission. Les moyens pour introduire et pour extraire le faisceau lumineux pouvant etre constitues par des guides de lumiere, notamment des fibres optiques