On the methodology of Mössbauer spectroscopy with67Zn

Conclusions The piezoceramic vibrators have the advantages of simplicity and stability of operation over those with quartz plates. However, the former show mechanical hysteresis causing distortions of the motion. This effect can be reduced by an appropriate choice of the ceramic cylinder, but it is not completely avoidable. That is why these distortions should be taken into account or quartz vibrators should be used in precision measurements. The displacement piezoceramic sensor described here gives new methodological opportunities in assembling and preliminary testing of the vibrators to find the optimum of construction and operating conditions as well as for continuous motion control during spectrum accumulation and eventual corrections of the motion distortions.     

Sound-based analogue of cavity quantum electrodynamics in silicon

A quantum mechanical superposition of a long-lived, localized phonon and a matter excitation is described. We identify a realization in strained silicon: a low-lying donor transition (P or Li) driven solely by acoustic phonons at wavelengths where high-Q phonon cavities can be built. This phonon-matter resonance is shown to enter the strongly coupled regime where the "vacuum" Rabi frequency exceeds the spontaneous phonon emission into noncavity modes, phonon leakage from the cavity, and phonon anharmonicity and scattering. We introduce a micropillar distributed Bragg reflector Si/Ge cavity, where Q?10(5)-10(6) and mode volumes V?25λ(3) are reachable. These results indicate that single or many-body devices based on these systems are experimentally realizable.     

Measurements of delayed-neutron yields from thermal-neutron-induced fission of 235U, 233U, 239Pu, and 237Np

The experimental results on delayed-neutron yields from thermal-neutron-induced fission of some actinides in the IBR-2 pulsed reactor are presented. A method of periodic irradiation without displacement of the sample was used. The measurements of delayed-neutron total yields in thermal-neutron-induced fission of ²³⁹Pu, ²³³U, and ²³⁷Np and in cold-neutron-induced fission of ²³⁵U, ²³³U, and ²³⁹Pu were carried out. All values were obtained with the use of the value of β₀ for (n _th+²³⁵U) as a reference. Precise measurements of decay curves in the time interval 5–350 ms for ²³⁵U and ²³⁹Pu were performed.     

Determination of Moisture Content in Coke with <Superscript>239</Superscript>Pu–Be Neutron Source and BGO Scintillation Gamma Detector

A series of experiments has been conducted at the Frank Laboratory of Neutron Physics (FLNP) of the Joint Institute for Nuclear Research (JINR) in order to study the possibility of determining the moisture content of coke using a standard neutron source. The proposed method is based on a measurement of the spectrum of prompt γ rays emitted when samples are irradiated by fast and/or thermal neutrons. The moisture content is determined from the area of the peaks of characteristic γ rays produced in the radiative capture of thermal neutrons by the proton (E_γ = 2.223 MeV) and inelastic scattering of fast neutrons by ¹⁶O (E_γ = 6.109 MeV). The ²³⁹Pu–Be neutron source (〈E _n 〉 ~ 4.5 MeV) with an intensity of ~5 × 10⁶ n/s was used to irradiate the samples under study. A scintillation detector based on a BGO crystal was used to register the characteristic γ radiation from the inelastic fast neutron scattering and slow (thermal) neutron capture. This paper presents the results of humidity measurement in the range of 2–50% [1, 2].     

Elemental Analysis of Engine Parts of the Proton Rocket Carrier with Resonance Neutrons

At the JINR Laboratory of Nuclear Physics, neutron–nucleus interactions are investigated for fundamental and applied purposes using the IREN pulsed neutron source. The applied research includes an elemental analysis of constituent materials of various devices. This paper describes the elemental-analysis techniques employed and reports the measurement of palladium abundances in the engine components of the Proton rocket carrier. The elemental-analysis technique involving resonance neutrons, currently implemented with the Romashka apparatus, is shown to be sensitive to palladium abundances at a level of 2 mg/g for samples with masses on the order of 60 g. Further developing the method will boost its sensitivity and allow for elemental analyses of larger samples and their assemblies.     

A Mössbauer study of the morin transition on the surface and in the bulk of hematite single crystals

The Morin transition has been studied simultaneously by transmission and conversion electron Mössbauer spectroscopy on the surface and in the bulk of hematite single-crystal plates with orientation (111) and different origin. It was found that in both samples, the surface transition is shifted to higher temperatures with respect to the bulk.     

Alpha-channeling simulation experiment in the DIII-D tokamak

Alfvén instabilities can reduce the central magnetic shear via redistribution of energetic ions. They can sustain a steady state internal transport barrier as demonstrated in this DIII-D tokamak experiment. Improvement in burning plasma performance based on this mechanism is discussed.     

Signatures of quantum behavior in single-qubit weak measurements

With the recent surge of interest in quantum computation, it has become very important to develop clear experimental tests for "quantum behavior" in a system. This issue has been addressed in the past in the form of the inequalities due to Bell and those due to Leggett and Garg. These inequalities concern the results of ideal projective measurements, however, which are experimentally difficult to perform in many proposed qubit designs, especially in many solid-state qubit systems. Here, we show that weak continuous measurements, which are often practical to implement experimentally, can yield particularly clear signatures of quantum coherence, both in the measured correlation functions and in the measured power spectrum.