http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Modulation, asymmetry and the diurnal variation in axionic dark matter searches
Semertzidis, Y.,Vergados, J.D. North Holland 2015 Nuclear Physics, Section B Vol.897 No.-
In the present work we study possible time dependent effects in Axion Dark Matter searches employing resonant cavities. We find that the width of the resonance, which depends on the axion mean square velocity in the local frame, will show an annual variation due to the motion of the Earth around the sun (modulation). Furthermore, if the experiments become directional, employing suitable resonant cavities, one expects large asymmetries in the observed widths relative to the sun's direction of motion. Due to the rotation of the Earth around its axis, these asymmetries will manifest themselves as a diurnal variation in the observed width.
An implementation of spin-dependent hadron elastic scattering in GEANT4
정호용,원은일,Semertzidis Yannis K.,Stephenson Edward J.,Park Seongtae 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.80 No.6
An implementation of the spin-dependent differential cross-section is discussed for the elastic hadron–nucleus scattering process in the GEANT4. To validate our implementation, real measurement results of proton-carbon cross-section are compared and the results are discussed. This implementation is applied to study a proposed experiment on the proton electric dipole moment in particular the systematic effects of the experiment.
Axionic dark matter signatures in various halo models
Vergados, J.D.,Semertzidis, Y.K. North Holland 2017 Nuclear Physics, Section B Vol.915 No.-
In the present work we study possible signatures in the Axion Dark Matter searches. We focus on the dependence of the expected width in resonant cavities for various popular halo models, leading to standard velocity distributions, e.g. Maxwell-Boltzmann, as well as phase-mixed and non-virialized axionic dark matter (flows, caustic rings). We study, in particular, the time dependence of the resonance width (modulation) arising from such models. We find that the difference between the maximum (in June) and the minimum (in December) can vary by about 10% in the case of standard halos. In the case of mixed phase halos the variation is a bit bigger and for caustic rings the maximum is expected to occur a bit later. Experimentally such a modulation is observable with present technology.
Review of low-noise radio-frequency amplifiers based on superconducting quantum interference device
Lee, Y.H.,Chong, Y.,Semertzidis, Y.K. The Korea Institute of Applied Superconductivity a 2014 한국초전도저온공학회논문지 Vol.16 No.4
Superconducting quantum interference device (SQUID) is a sensitive detector of magnetic flux signals. Up to now, the main application of SQUIDs has been measurements of magnetic flux signals in the frequency range from near DC to several MHz. Recently, cryogenic low-noise radio-frequency (RF) amplifiers based on DC SQUID are under development aiming to detect RF signals with sensitivity approaching quantum limit. In this paper, we review the recent progress of cryogenic low-noise RF amplifiers based on SQUID technology.
이용호,유권규,김진목,S. K. Lee,정연욱,S. J. Oh,Y. K. Semertzidis 한국초전도.저온공학회 2018 한국초전도저온공학회논문지 Vol.20 No.4
Low-noise amplifiers in the radio-frequency (RF) band based on the direct current (DC) superconducting quantum interference device (SQUID) can be used for quantum-limited measurements in precision physics experiments. For the prediction of peak-gain frequency of these amplifiers, we need a reliable design formula for the resonance frequency of the microstrip circuit. We improved the formula for the resonance frequency, determined by parameters of the DC SQUID and the input coil, and compared the design values with experimental values. The proposed formula showed much accurate results than the conventional formula. Minor deviation of the experimental results from the theory can be corrected by using the measured geometrical parameters of the input coil line.
Concept of multiple-cell cavity for axion dark matter search
Jeong, Junu,Youn, SungWoo,Ahn, Saebyeok,Kim, Jihn E.,Semertzidis, Yannis K. Elsevier 2018 Physics letters: B Vol.777 No.-
<P><B>Abstract</B></P> <P>In cavity-based axion dark matter search experiments exploring high mass regions, multiple-cavity design is under consideration as a method to increase the detection volume within a given magnet bore. We introduce a new idea, referred to as a multiple-cell cavity, which provides various benefits including a larger detection volume, simpler experimental setup, and easier phase-matching mechanism. We present the characteristics of this concept and demonstrate the experimental feasibility with an example of a double-cell cavity.</P>
Detecting solar chameleons through radiation pressure
Baum, S.,Cantatore, G.,Hoffmann, D.H.H.,Karuza, M.,Semertzidis, Y.K.,Upadhye, A.,Zioutas, K. Elsevier 2014 Physics letters: B Vol.739 No.-
<P><B>Abstract</B></P> <P>Light scalar fields can drive the accelerated expansion of the universe. Hence, they are obvious dark energy candidates. To make such models compatible with tests of General Relativity in the solar system and “fifth force” searches on Earth, one needs to screen them. One possibility is the so-called “chameleon” mechanism, which renders an effective mass depending on the local matter density. If chameleon particles exist, they can be produced in the sun and detected on Earth exploiting the equivalent of a radiation pressure. Since their effective mass scales with the local matter density, chameleons can be reflected by a dense medium if their effective mass becomes greater than their total energy. Thus, under appropriate conditions, a flux of solar chameleons may be sensed by detecting the total instantaneous momentum transferred to a suitable opto-mechanical force/pressure sensor. We calculate the solar chameleon spectrum and the reach in the chameleon parameter space of an experiment using the preliminary results from a force/pressure sensor, currently under development at INFN Trieste, to be mounted in the focal plane of one of the X-Ray telescopes of the CAST experiment at CERN. We show, that such an experiment signifies a pioneering effort probing uncharted chameleon parameter space.</P>