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Experimental and theoretical studies of hyperfine structures in $^{21}$Na
Authors:
Junho Won,
Jeongsu Ha,
Deuk Soon Ahn,
Sunghoon Ahn,
Vivek Chavan,
Anastasiia Chekhovska,
Gyoungmo Gu,
Kevin Insik Hahn,
Seongjin Heo,
Jangyong Huh,
Dahee Kim,
Do Gyun Kim,
Dong Geon Kim,
Jung Bog Kim,
Sunji Kim,
Yeong Seok Kim,
Yung Hee Kim,
Zeren Korkulu,
Donghyeon Kwak,
Jens Lassen,
Jin Ho Lee,
Jung Woo Lee,
Chaeyeong Lim,
Joochun Park,
Ben Ohayon
, et al. (16 additional authors not shown)
Abstract:
We measured the hyperfine structure constants, $A(3s^2S_{1/2})$ and $A(3p^2P_{1/2})$, of the neutron-deficient isotope $^{21}\text{Na}$ using CLaSsy, a setup dedicated to collinear laser spectroscopy at RAON. The hyperfine structure constants of $^{21}\text{Na}$ were measured to be $103.6(10)_{\mathrm{stat}}(9)_{\mathrm{syst}}$ MHz for $A(3p^2P_{1/2})$ and…
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We measured the hyperfine structure constants, $A(3s^2S_{1/2})$ and $A(3p^2P_{1/2})$, of the neutron-deficient isotope $^{21}\text{Na}$ using CLaSsy, a setup dedicated to collinear laser spectroscopy at RAON. The hyperfine structure constants of $^{21}\text{Na}$ were measured to be $103.6(10)_{\mathrm{stat}}(9)_{\mathrm{syst}}$ MHz for $A(3p^2P_{1/2})$ and $954.9(11)_{\mathrm{stat}}(25)_{\mathrm{syst}}$ MHz for $A(3s^2S_{1/2})$. A systematic comparison with the state-of-the-art ab-initio relativistic coupled cluster calculations shows the role of higher-order correlation effects such as triple excitations in $^{21}$Na. Furthermore, the measurement demonstrates a capability of the CLaSsy setup to conduct collinear laser spectroscopy experiments with a radioactive beam.
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Submitted 26 May, 2026;
originally announced May 2026.
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Design of the Global Reconstruction Logic in the Belle II Level-1 Trigger system
Authors:
Y. -T. Lai,
T. Koga,
Y. Iwasaki,
Y. Ahn,
H. Bae,
M. Campajola,
B. G. Cheon,
H. -E. Cho,
T. Ferber,
I. Haide,
G. Heine,
C. -L. Hsu,
C. Kiesling,
C. -H. Kim,
J. B. Kim,
K. Kim,
S. H. Kim,
I. S. Lee,
M. J. Lee,
Y. P. Liao,
J. Lin,
A. Little,
H. K. Moon,
H. Nakazawa,
M. Neu
, et al. (10 additional authors not shown)
Abstract:
The Belle~II experiment is designed to search for physics beyond the Standard Model by investigating rare decays at the SuperKEKB \(e^{+}e^{-}\) collider. Owing to the significant beam background at high luminosity, the data acquisition system employs a hardware-based Level-1~Trigger to reduce the readout data throughput by selecting collision events of interest in real time. The Belle~II Level-1~…
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The Belle~II experiment is designed to search for physics beyond the Standard Model by investigating rare decays at the SuperKEKB \(e^{+}e^{-}\) collider. Owing to the significant beam background at high luminosity, the data acquisition system employs a hardware-based Level-1~Trigger to reduce the readout data throughput by selecting collision events of interest in real time. The Belle~II Level-1~Trigger system utilizes FPGAs to reconstruct various detector observables from the raw data for trigger decision-making. The Global Reconstruction Logic receives these processed observables from four sub-trigger systems and provides a global summary for the final trigger decision. Its logic encompasses charged particle tracking, matching between sub-triggers, and the identification of special event topologies associated with low-multiplicity decays. This article discusses the hardware devices, FPGA firmware, integration with peripheral systems, and the design and performance of the trigger algorithms implemented within the Global Reconstruction Logic.
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Submitted 3 March, 2025;
originally announced March 2025.
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Hyperfine and Zeeman Optical Pumping and Transverse Laser Cooling of a Thermal Atomic Beam of Dysprosium Using a Single 421 nm Laser
Authors:
Rohan Chakravarthy,
Jonathan Agil,
Arijit Sharma,
Jung Bog Kim,
Dmitry Budker
Abstract:
We demonstrate the effect of Zeeman and hyperfine optical pumping and transverse laser cooling of a dysprosium (Dy) atomic beam on the $4f^{10}6s^2(J = 8) \rightarrow 4f^{10}6s6p(J = 9)$ transition at 421.291 nm. For $^{163}$Dy, an electro-optic modulator is used to generate five frequency sidebands required to pump the atoms to the $F = 10.5$ ground state hyperfine level and the light polarizatio…
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We demonstrate the effect of Zeeman and hyperfine optical pumping and transverse laser cooling of a dysprosium (Dy) atomic beam on the $4f^{10}6s^2(J = 8) \rightarrow 4f^{10}6s6p(J = 9)$ transition at 421.291 nm. For $^{163}$Dy, an electro-optic modulator is used to generate five frequency sidebands required to pump the atoms to the $F = 10.5$ ground state hyperfine level and the light polarization is chosen to pump the atoms to the $m_F = 10.5$ Zeeman sublevel. The atoms are simultaneously laser-cooled using a standing wave orthogonal to the atomic beam. The resulting polarized and cooled atomic beam will be used in fundamental physics experiments taking advantage of the accidental degeneracy of excited states in Dy including the ongoing measurement of parity violation in this system.
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Submitted 15 December, 2025; v1 submitted 24 February, 2025;
originally announced February 2025.
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Coherent amplitude modulation of continuous-wave light in cesium vapor
Authors:
X. Zhang,
J. B. Kim,
D. Antypas
Abstract:
We report on observations of coherent, sustained oscillations in the absorption of continuous-wave light at 388 nm that excites the $6S_{1/2}\rightarrow 8P_{3/2}$ transition in cesium vapor. The oscillation frequency is close to the spacing of hyperfine levels of the $8P_{3/2}$ level that are excited simultaneously by the 388 nm field. We observe threshold behavior of the oscillation amplitude wit…
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We report on observations of coherent, sustained oscillations in the absorption of continuous-wave light at 388 nm that excites the $6S_{1/2}\rightarrow 8P_{3/2}$ transition in cesium vapor. The oscillation frequency is close to the spacing of hyperfine levels of the $8P_{3/2}$ level that are excited simultaneously by the 388 nm field. We observe threshold behavior of the oscillation amplitude with pump power, and suggest that the effect is associated with infrared directional emission due to amplified spontaneous emission from the $8P_{3/2}\rightarrow 8S_{1/2}$ transition, that is assisted by retro-reflections from the cell windows. The effect may be used to probe a lasing process in an atomic vapor, by checking the temporal properties of the pump field transmitted through the vapor.
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Submitted 15 June, 2024;
originally announced June 2024.
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Speed of sound in methane under conditions of planetary interiors
Authors:
Thomas G. White,
Hannah Poole,
Emma E. McBride,
Matthew Oliver,
Adrien Descamps,
Luke B. Fletcher,
W. Alex Angermeier,
Cameron H. Allen,
Karen Appel,
Florian P. Condamine,
Chandra B. Curry,
Francesco Dallari,
Stefan Funk,
Eric Galtier,
Eliseo J. Gamboa,
Maxence Gauthier,
Peter Graham,
Sebastian Goede,
Daniel Haden,
Jongjin B. Kim,
Hae Ja Lee,
Benjamin K. Ofori-Okai,
Scott Richardson,
Alex Rigby,
Christopher Schoenwaelder
, et al. (10 additional authors not shown)
Abstract:
We present direct observations of acoustic waves in warm dense matter. We analyze wave-number- and energy-resolved x-ray spectra taken from warm dense methane created by laser heating a cryogenic liquid jet. X-ray diffraction and inelastic free-electron scattering yield sample conditions of 0.3$\pm$0.1 eV and 0.8$\pm$0.1 g/cm$^3$, corresponding to a pressure of $\sim$13 GPa. Inelastic x-ray scatte…
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We present direct observations of acoustic waves in warm dense matter. We analyze wave-number- and energy-resolved x-ray spectra taken from warm dense methane created by laser heating a cryogenic liquid jet. X-ray diffraction and inelastic free-electron scattering yield sample conditions of 0.3$\pm$0.1 eV and 0.8$\pm$0.1 g/cm$^3$, corresponding to a pressure of $\sim$13 GPa. Inelastic x-ray scattering was used to observe the collective oscillations of the ions. With a highly improved energy resolution of $\sim$50 meV, we could clearly distinguish the Brillouin peaks from the quasielastic Rayleigh feature. Data at different wave numbers were utilized to derive a sound speed of 5.9$\pm$0.5 km/s, marking a high-temperature data point for methane and demonstrating consistency with Birch's law in this parameter regime.
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Submitted 3 May, 2024; v1 submitted 13 November, 2023;
originally announced November 2023.
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Measurement of effective thermal conductivity of LaNi$_5$ powder packed bed
Authors:
Dong-min Kim,
Joong Bae Kim,
Jungchul Lee,
Bong Jae Lee
Abstract:
Effective thermal conductivity of LaNi$_5$ powder packed bed was analyzed with customized guarded hot-plate (GHP) apparatus. Here, GHP was designed for precise measurement of effective thermal conductivity of metal-hydride powders even with small sample amounts (2.12$\times$10$^4$ mm$^3$). Dimensions of sample container and apparatus were determined through two-dimensional (2-D) steady-state heat…
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Effective thermal conductivity of LaNi$_5$ powder packed bed was analyzed with customized guarded hot-plate (GHP) apparatus. Here, GHP was designed for precise measurement of effective thermal conductivity of metal-hydride powders even with small sample amounts (2.12$\times$10$^4$ mm$^3$). Dimensions of sample container and apparatus were determined through two-dimensional (2-D) steady-state heat conduction analysis. Calibration experiment and uncertainty analysis were conducted to validate the accuracy of the GHP. Based on the measurements of the residual thermal conductivity of the LaNi$_5$ packed bed, effect of particle size on contact factor of LaNi$_5$ packed bed was estimated. By applying the Yagi and Kunii (YK) model to the effective thermal conductivity of LaNi$_5$ packed bed, effect of contact factor and gas thermal conductivity on characteristic length of gas film were newly analyzed. Factors of YK model were modified in present work and validated through comparison with experimental data from previous literature.
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Submitted 12 May, 2020;
originally announced May 2020.
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Performance analysis of a direct-absorption parabolic trough solar collector
Authors:
Caiyan Qin,
Joong Bae Kim,
Bong Jae Lee
Abstract:
A parabolic trough solar collector is a dominant technology for high-temperature industrial applications, but efficient use of a conventional surface-based parabolic trough solar collector (SBPTSC) is limited by its high radiation loss due to the high surface temperature. Recently, direct-absorption parabolic trough solar collector (DAPTSC) using nanofluids has been proposed, and its thermal effic…
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A parabolic trough solar collector is a dominant technology for high-temperature industrial applications, but efficient use of a conventional surface-based parabolic trough solar collector (SBPTSC) is limited by its high radiation loss due to the high surface temperature. Recently, direct-absorption parabolic trough solar collector (DAPTSC) using nanofluids has been proposed, and its thermal efficiency has been reported to be 5-10$\%$ higher than the conventional SBPTSC for inlet temperature up to 250$^\circ$C. However, the inner tubes of the receivers of the existing DAPTSCs are all transparent, so the sun rays entering the inner tube can only travel once through the nanofluids. As a result, the optical path length for the sun rays is limited by the inner tube size, which in turn requires high value of the absorption coefficient of nanofluids. Due to the approximately linear relation between the absorption coefficient and the particle concentration, higher absorption coefficient is likely to cause particle agglomeration, leading to detrimental effects on maintaining stable collector performance. In the current study, the transparent DAPTSC is improved by applying a reflective coating on the upper half of the inner tube outer surface, such that the optical path length is doubled compared to the transparent DAPTSC; thus, the absorption coefficient of the nanofluids can be reduced accordingly. The coated DAPTSC is found to have obvious advantage compared to the transparent DAPTSC at absorption coefficient below 0.5 cm$^{-1}$ for a receiver with inner tube diameter of 7 cm. In addition, performance of the transparent DAPTSC, the coated DAPTSC and the SBPTSC with black chrome coating have been compared to explore their advantageous operation conditions, such as inner tube diameter, flow rate, and inlet temperature, with or without a glass envelope for vacuum evacuation.
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Submitted 20 October, 2018;
originally announced October 2018.
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Setup for meV-resolution inelastic X-ray scattering measurements at the Matter in Extreme Conditions Endstation at the LCLS
Authors:
E. E. McBride,
T. G. White,
A. Descamps,
L. B. Fletcher,
K. Appel,
F. Condamine,
C. B. Curry,
F. Dallari,
S. Funk,
E. Galtier,
M. Gauthier,
S. Goede,
J. B. Kim,
H. J. Lee,
B. K. Ofori-Okai,
M. Oliver,
A. Rigby,
C. Schoenwaelder,
P. Sun,
Th. Tschentscher,
B. B. L. Witte,
U. Zastrau,
G. Gregori,
B. Nagler,
J. Hastings
, et al. (2 additional authors not shown)
Abstract:
We describe a setup for performing inelastic X-ray scattering measurements at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source (LCLS). This technique is capable of performing high-, meV-resolution measurements of dynamic ion features in both crystalline and non-crystalline materials. A four-bounce silicon (533) monochromator was used in conjunction with three si…
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We describe a setup for performing inelastic X-ray scattering measurements at the Matter in Extreme Conditions (MEC) endstation of the Linac Coherent Light Source (LCLS). This technique is capable of performing high-, meV-resolution measurements of dynamic ion features in both crystalline and non-crystalline materials. A four-bounce silicon (533) monochromator was used in conjunction with three silicon (533) diced crystal analyzers to provide an energy resolution of ~50 meV over a range of ~500 meV in single shot measurements. In addition to the instrument resolution function, we demonstrate the measurement of longitudinal acoustic phonon modes in polycrystalline diamond. Furthermore, this setup may be combined with the high intensity laser drivers available at MEC to create warm dense matter, and subsequently measure ion acoustic modes.
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Submitted 5 June, 2018;
originally announced June 2018.
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Three dimensional fast tracker for central drift chamber based level 1 trigger system in the Belle II experiment
Authors:
E. Won,
J. B. Kim,
B. R. Ko
Abstract:
The Belle II detector at the SuperKEKB accelerator has a level 1 trigger implemented in field-programmable gate arrays. Due to the high luminosity of the beam, a trigger that effectively rejects beam induced background is required. A three dimensional tracking algorithm for the level 1 trigger that uses the Belle II central drift chamber detector response is being developed to reduce the recorded…
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The Belle II detector at the SuperKEKB accelerator has a level 1 trigger implemented in field-programmable gate arrays. Due to the high luminosity of the beam, a trigger that effectively rejects beam induced background is required. A three dimensional tracking algorithm for the level 1 trigger that uses the Belle II central drift chamber detector response is being developed to reduce the recorded beam background while having a high efficiency for physics of interest. In this paper, we describe the three dimensional track trigger that finds and fits track parameters which we developed.
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Submitted 7 November, 2017;
originally announced November 2017.
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A software framework for pipelined arithmetic algorithms in field programmable gate arrays
Authors:
J. B. Kim,
E. Won
Abstract:
Pipelined algorithms implemented in field programmable gate arrays are being extensively used for hardware triggers in the modern experimental high energy physics field and the complexity of such algorithms are increases rapidly. For development of such hardware triggers, algorithms are developed in $\texttt{C++}$, ported to hardware description language for synthesizing firmware, and then ported…
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Pipelined algorithms implemented in field programmable gate arrays are being extensively used for hardware triggers in the modern experimental high energy physics field and the complexity of such algorithms are increases rapidly. For development of such hardware triggers, algorithms are developed in $\texttt{C++}$, ported to hardware description language for synthesizing firmware, and then ported back to $\texttt{C++}$ for simulating the firmware response down to the single bit level. We present a $\texttt{C++}$ software framework which automatically simulates and generates hardware description language code for pipelined arithmetic algorithms.
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Submitted 13 December, 2017; v1 submitted 20 October, 2017;
originally announced October 2017.
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Matter-wave beam splitter on an atom chip for a portable atom-interferometer
Authors:
S. J. Kim,
H. Yu,
S. T. Gang,
J. B. Kim
Abstract:
We construct a matter-wave beam splitter using 87Rb Bose-Einstein condensate on an atom chip. Through the use of radio-frequency-induced double-well potentials, we were able to split a BEC into two clouds separated by distances ranging from 2.8 μm to 57 μm. Interference between these two freely expanding BECs has been observed. By varying the rf-field amplitude, frequency, or polarization, we inve…
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We construct a matter-wave beam splitter using 87Rb Bose-Einstein condensate on an atom chip. Through the use of radio-frequency-induced double-well potentials, we were able to split a BEC into two clouds separated by distances ranging from 2.8 μm to 57 μm. Interference between these two freely expanding BECs has been observed. By varying the rf-field amplitude, frequency, or polarization, we investigate behaviors of the beam-splitter. From the perspective of practical use, our BEC manipulation system is suitable for application to interferometry since it is compact and the repetition rate is high due to the anodic bonded atom chip on the vacuum cell. The portable system occupies a volume of 0.5 m3 and operates at a repetition rate as high as ~0.2 Hz.
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Submitted 26 January, 2016;
originally announced January 2016.
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Controllable Asymmetric Matter-wave Beam Splitter and Ring Potential on an Atom Chip
Authors:
S. J. Kim,
H. Yu,
S. T. Gang,
D. Anderson,
J. B. Kim
Abstract:
We have constructed an asymmetric matter-wave beam splitter and a ring potential on an atom chip with Bose-Einstein condensates using radio-frequency dressing. By applying rf-field parallel to the quantization axis in the vicinity of the static trap minima added to perpendicular rf-fields, versatile controllability on the potentials is realized. Asymmetry of the rf-induced double well is manipulat…
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We have constructed an asymmetric matter-wave beam splitter and a ring potential on an atom chip with Bose-Einstein condensates using radio-frequency dressing. By applying rf-field parallel to the quantization axis in the vicinity of the static trap minima added to perpendicular rf-fields, versatile controllability on the potentials is realized. Asymmetry of the rf-induced double well is manipulated without discernible displacement of the each well along horizontal and vertical direction. Formation of an isotropic ring potential on an atom chip is achieved by compensating the gradient due to gravity and inhomogeneous coupling strength. In addition, position and rotation velocity of a BEC along the ring geometry are controlled by the relative phase and the frequency difference between the rf-fields, respectively.
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Submitted 2 June, 2015;
originally announced June 2015.
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Modified "delta kick cooling" for studies of atomic tunneling
Authors:
S. H. Myrskog,
J. K. Fox,
H. S. Moon,
H. A. Kim,
J. B. Kim,
A. M. Steinberg
Abstract:
We present progress towards a planned experiment on atomic tunneling of ultra-cold Rb atoms. As a first step in this experiment we present a realization of an improved form of "delta-kick cooling." By application of a pulsed magnetic field, laser cooled Rb atoms are further cooled by a factor of 10 (in 1-D) over the temperature out of molasses. Temperatures below 700 nK are observed. The techniq…
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We present progress towards a planned experiment on atomic tunneling of ultra-cold Rb atoms. As a first step in this experiment we present a realization of an improved form of "delta-kick cooling." By application of a pulsed magnetic field, laser cooled Rb atoms are further cooled by a factor of 10 (in 1-D) over the temperature out of molasses. Temperatures below 700 nK are observed. The technique can be used not only to cool without fundamental limit (but conserving phase-space density), but also to focus atoms, and as a spin-dependent probe.
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Submitted 31 March, 1999; v1 submitted 14 December, 1998;
originally announced December 1998.