The Experts below are selected from a list of 8736 Experts worldwide ranked by ideXlab platform
T Idehara - One of the best experts on this subject based on the ideXlab platform.
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Frequency Tunable sub-THz Gyrotron for Direct Measurements of Positronium Hyperfine Structure
2018Co-Authors: A. E. Fedotov, R. M. Rozental, I. V. Zotova, N. S. Ginzburg, A. S. Sergeev, V. P. Tarakanov, M. Yu. Glyavin, T IdeharaAbstract:The feasibility of a high-power sub-THz gyrotron with smooth wideband frequency tuning suitable for direct measurement of the Positronium hyperfine structure is demonstrated numerically using both averaged equations and PIC-code simulations. Analytical estimates show that the frequency-tunable powerful sub-THz radiation can be generated through the excitation of high-order axial modes in a gyrotron with short cavity driven by an electron beam with high current. Simulations show that an output power of 0.5–1 kW can be obtained at a frequency of about 0.2 THz within a 10-GHz band which are the parameters needed for testing of quantum electrodynamics predictions through the spectroscopy of Positronium.
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first millimeter wave spectroscopy of ground state Positronium
2015Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, Y Tatematsu, I Ogawa, T Kobayashi, T IdeharaAbstract:We report on the first measurement of the Breit-Wigner resonance of the transition from ortho-Positronium to para-Positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron ! "#!
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first millimeter wave spectroscopy of the ground state Positronium
2014Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, Y Tatematsu, I Ogawa, T Kobayashi, T IdeharaAbstract:We report on the first measurement of the Breit-Wigner resonance of the transition from {\it ortho-}Positronium to {\it para-}Positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron and a Fabry-Perot cavity. This system opens a new era of millimeter-wave spectroscopy, and enables us to directly determine both the hyperfine interval and the decay width of {\it p-}Ps.
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the sub thz direct spectroscopy of Positronium hyperfine splitting
2013Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, T Kobayashi, Y Tatematsu, I Ogawa, T IdeharaAbstract:The Positronium hyperfine splitting is a good target to study Quantum Electrodynamics in the bound state. There is a discrepancy between precision measurements and a theoretical calculation. We are planning to directly measure the positroinum hyperfine structure for the first time. A gyrotron oscillator is used as a novel radiation source in terahertz region. A Fabry-Perot resonator is also developed to increase photon density. We have already observed the direct transition at 202.9 GHz. The direct measurement of the order of 100 ppm will be performed within about a year.
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first observation of o ps to p ps transition and first direct measurement of Positronium hyperfine splitting with sub thz light
2012Co-Authors: Takayuki Yamazaki, Haruo Saito, Taikan Suehara, A Miyazaki, T Namba, S Asai, T Kobayashi, I Ogawa, Y Urushizaki, T IdeharaAbstract:Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of Positronium (Ps-HFS, about 203 GHz) is an important observable but all previous measurements of Ps-HFS had been measured indirectly using Zeeman splitting. There might be the unknown systematic errors on the uniformity of magnetic field. We are trying to measure Ps-HFS directly using sub-THz radiation. We developed an optical system to accumulate high power (about 10 kW) radiation in a Fabry-Perot resonant cavity and observed the Positronium hyperfine transition for the first time.
A P Mills - One of the best experts on this subject based on the ideXlab platform.
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single shot positron annihilation lifetime spectroscopy
2006Co-Authors: D B Cassidy, S H M Deng, Hiroyuki Tanaka, A P MillsAbstract:Recent developments in positron trapping technology have made possible experimentation with dense interacting Positronium gases. Along with these capabilities comes a need for suitable measurement techniques, and accordingly we have developed a method to measure Positronium lifetimes from a single intense burst of positrons. Our method is based on recording the anode signal from a photomultiplier with a fast oscilloscope following a short-time positron burst which allows us to measure transitory effects as well as high density Positronium interactions.
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experiments with a high density Positronium gas
2005Co-Authors: D B Cassidy, S H M Deng, Hiroyuki Tanaka, R G Greaves, T Maruo, Norikazu Nishiyama, J B Snyder, A P MillsAbstract:We have created a high-density gas of interacting Positronium (Ps) atoms by irradiating a thin film of nanoporous silica with intense positron bursts and measured the Ps lifetime using a new single-shot technique. When the positrons were compressed to 3.3 x 10(10) cm-2, the apparent intensity of the orthoPositronium lifetime component was found to decrease by 33%. We believe this is due to a combination of spin exchange quenching and PS2 molecule formation associated with colliding pairs of oppositely polarized triplet Positronium atoms. Our data imply an effective cross section for this process of 2.9 x 10(-14) cm-2.
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can we measure the gravitational free fall of cold rydberg state Positronium
2002Co-Authors: A P Mills, M LeventhalAbstract:Abstract In this paper we examine the possibilities for detecting the free fall of Rydberg Positronium atoms. In our scheme, cold Positronium atoms are emitted from a “point” source and excited to the n=25 circular Rydberg state with L=n−1. The Positronium atoms are allowed to travel horizontally 10 m in a field free vacuum and focused onto a detector using an elliptical Van der Waals mirror. A free fall distance of order 50 μm and a few detected atoms per hour are anticipated. Various extraneous influences on the Positronium, such as collisions with residual gas atoms, Stark mixing in stray electric and magnetic fields, photoionization due to thermal radiation, and accelerations due to patch potentials are estimated.
S Asai - One of the best experts on this subject based on the ideXlab platform.
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study on cooling of Positronium for bose einstein condensation
2016Co-Authors: K Shu, Takayuki Yamazaki, T Namba, S Asai, Xing Fan, K Yoshioka, Makoto KuwatagonokamiAbstract:A proposed new method of cooling Positronium is to realize the Bose–Einstein condensation (BEC) of Positronium. We perform detailed studies of three processes: (1) thermalization processes between Positronium and the silica walls of a cavity, (2) Ps–Ps scattering and (3) laser cooling. The thermalization process is shown to be not sufficient for BEC. Ps–Ps collision is shown to have a big effect on the cooling performance. We combine both methods and establish an efficient cooling process for BEC. We also propose a new optical laser system for the cooling.
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study on cooling of Positronium for bose einstein condensation
2015Co-Authors: K Shu, Takayuki Yamazaki, T Namba, S Asai, Xing Fan, K Yoshioka, Makoto KuwatagonokamiAbstract:A new method of cooling Positronium down is proposed to realize Bose-Einstein condensation of Positronium. We perform detail studies about three processes (1) thermalization processes between Positronium and silica walls of a cavity, (2) Ps-Ps scatterings and (3) Laser cooling. The thermalization process is shown to be not sufficient for BEC. Ps-Ps collision is also shown to make a big effect on the cooling performance. We combine both methods and establish an efficient cooling for BEC. We also propose a new optical laser system for the cooling.
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first millimeter wave spectroscopy of ground state Positronium
2015Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, Y Tatematsu, I Ogawa, T Kobayashi, T IdeharaAbstract:We report on the first measurement of the Breit-Wigner resonance of the transition from ortho-Positronium to para-Positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron ! "#!
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first millimeter wave spectroscopy of the ground state Positronium
2014Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, Y Tatematsu, I Ogawa, T Kobayashi, T IdeharaAbstract:We report on the first measurement of the Breit-Wigner resonance of the transition from {\it ortho-}Positronium to {\it para-}Positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron and a Fabry-Perot cavity. This system opens a new era of millimeter-wave spectroscopy, and enables us to directly determine both the hyperfine interval and the decay width of {\it p-}Ps.
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sub thz spectroscopy of the ground state hyperfine splitting of Positronium
2013Co-Authors: Takayuki Yamazaki, Taikan Suehara, A Miyazaki, T Namba, S Asai, T Kobayashi, Y Tatematsu, I Ogawa, T IdeharacAbstract:We plan to directly measure the hyperfine structure of the ground-state Positronium. The hyperfine structure between ortho-Positronium and para-Positronium is about 203 GHz. We develop a new optical system to accumulate about 20 kW power using a gyrotron and high finesse Fabry-Perot resonator. We report the current status of our experiment.
T Namba - One of the best experts on this subject based on the ideXlab platform.
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study on cooling of Positronium for bose einstein condensation
2016Co-Authors: K Shu, Takayuki Yamazaki, T Namba, S Asai, Xing Fan, K Yoshioka, Makoto KuwatagonokamiAbstract:A proposed new method of cooling Positronium is to realize the Bose–Einstein condensation (BEC) of Positronium. We perform detailed studies of three processes: (1) thermalization processes between Positronium and the silica walls of a cavity, (2) Ps–Ps scattering and (3) laser cooling. The thermalization process is shown to be not sufficient for BEC. Ps–Ps collision is shown to have a big effect on the cooling performance. We combine both methods and establish an efficient cooling process for BEC. We also propose a new optical laser system for the cooling.
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study on cooling of Positronium for bose einstein condensation
2015Co-Authors: K Shu, Takayuki Yamazaki, T Namba, S Asai, Xing Fan, K Yoshioka, Makoto KuwatagonokamiAbstract:A new method of cooling Positronium down is proposed to realize Bose-Einstein condensation of Positronium. We perform detail studies about three processes (1) thermalization processes between Positronium and silica walls of a cavity, (2) Ps-Ps scatterings and (3) Laser cooling. The thermalization process is shown to be not sufficient for BEC. Ps-Ps collision is also shown to make a big effect on the cooling performance. We combine both methods and establish an efficient cooling for BEC. We also propose a new optical laser system for the cooling.
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first millimeter wave spectroscopy of ground state Positronium
2015Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, Y Tatematsu, I Ogawa, T Kobayashi, T IdeharaAbstract:We report on the first measurement of the Breit-Wigner resonance of the transition from ortho-Positronium to para-Positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron ! "#!
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first millimeter wave spectroscopy of the ground state Positronium
2014Co-Authors: A Miyazaki, Haruo Saito, Taikan Suehara, Takayuki Yamazaki, T Namba, S Asai, Y Tatematsu, I Ogawa, T Kobayashi, T IdeharaAbstract:We report on the first measurement of the Breit-Wigner resonance of the transition from {\it ortho-}Positronium to {\it para-}Positronium. We have developed an optical system to accumulate a power of over 20 kW using a frequency-tunable gyrotron and a Fabry-Perot cavity. This system opens a new era of millimeter-wave spectroscopy, and enables us to directly determine both the hyperfine interval and the decay width of {\it p-}Ps.
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sub thz spectroscopy of the ground state hyperfine splitting of Positronium
2013Co-Authors: Takayuki Yamazaki, Taikan Suehara, A Miyazaki, T Namba, S Asai, T Kobayashi, Y Tatematsu, I Ogawa, T IdeharacAbstract:We plan to directly measure the hyperfine structure of the ground-state Positronium. The hyperfine structure between ortho-Positronium and para-Positronium is about 203 GHz. We develop a new optical system to accumulate about 20 kW power using a gyrotron and high finesse Fabry-Perot resonator. We report the current status of our experiment.
Savely G Karshenboim - One of the best experts on this subject based on the ideXlab platform.
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precision physics of simple atoms qed tests nuclear structure and fundamental constants
2005Co-Authors: Savely G KarshenboimAbstract:Abstract Quantum electrodynamics (QED) is the first successful and still the most successful quantum field theory. Simple atoms, being essentially QED systems, allow highly accurate theoretical predictions. Because of their simple spectra, such atoms have also been efficiently studied experimentally frequently offering the most precisely measured quantities. Our review is devoted to comparison of theory and experiment in the field of precision physics of light simple atoms. In particular, we consider the Lamb shift in the hydrogen atom, the hyperfine structure in hydrogen, deuterium, helium-3 ion, muonium and Positronium, as well as a number of other transitions in Positronium. Additionally to a spectrum of unperturbed atoms, we consider annihilation decay of Positronium and the g factor of bound particles in various two-body atoms. Special attention is paid to the uncertainty of the QED calculations due to the uncalculated higher-order corrections and effects of the nuclear structure. We also discuss applications of simple atoms to determination of several fundamental constants.
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precision physics of simple atoms qed tests nuclear structure and fundamental constants
2005Co-Authors: Savely G KarshenboimAbstract:Quantum electrodynamics is the first successful and still the most successful quantum field theory. Simple atoms, being essentially QED systems, allow highly accurate theoretical predictions. Because of their simple spectra, such atoms have been also efficiently studied experimentally frequently offering the most precisely measured quantities. Our review is devoted to comparison of theory and experiment in the field of precision physics of light simple atoms. In particular, we consider the Lamb shift in the hydrogen atom, the hyperfine structure in hydrogen, deuterium, helium-3 ion, muonium and Positronium, as well as a number of other transitions in Positronium. Additionally to a spectrum of unperturbed atoms, we consider annihilation decay of Positronium and the g factor of bound particles in various two-body atoms. Special attention is paid to the uncertainty of the QED calculations due to the uncalculated higher-order corrections and effects of the nuclear structure. We also discuss applications of simple atoms to determination of several fundamental constants.
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precision study of Positronium testing bound state qed theory
2003Co-Authors: Savely G KarshenboimAbstract:As an unstable light pure leptonic system, Positronium is a very specific probe atom to test bound state QED. In contrast to ordinary QED for free leptons, the bound state QED theory is not so well understood and bound state approaches deserve highly accurate tests. We present a brief overview of precision studies of Positronium paying special attention to uncertainties of theory as well as comparison of theory and experiment. We also consider in detail advantages and disadvantages of Positronium tests compared to other QED experiments.
