S. Kokou Dadzie
A5082749731- Gas Dynamics and Kinetic Theory
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Lattice Boltzmann Simulation Studies
- Computational Fluid Dynamics and Aerodynamics
- Fluid Dynamics and Turbulent Flows
- Advanced Thermodynamics and Statistical Mechanics
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Plasma and Flow Control in Aerodynamics
- Planetary Science and Exploration
- Quantum Electrodynamics and Casimir Effect
- Phase Equilibria and Thermodynamics
- Atmospheric Ozone and Climate
- Radiation Therapy and Dosimetry
- Heat Transfer and Optimization
- nanoparticles nucleation surface interactions
- Methane Hydrates and Related Phenomena
- Hydraulic Fracturing and Reservoir Analysis
- Neutrino Physics Research
- Quantum, superfluid, helium dynamics
- Spacecraft and Cryogenic Technologies
- Radioactive contamination and transfer
- Atomic and Subatomic Physics Research
- Nanopore and Nanochannel Transport Studies
Massachusetts Institute of Technology
2017-2025
Heriot-Watt University
2016-2022
Johnson Space Center
2020
National Aeronautics and Space Administration
2020
Heriot-Watt University Malaysia
2014-2015
Wrexham University
2012-2013
University of Strathclyde
2008-2011
Institut Universitaire des Systèmes Thermiques Industriels
2005
Centre National de la Recherche Scientifique
2004-2005
Université Paris Cité
2005
The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector on the International Space Station (ISS) conducting unique, long-duration mission of fundamental research in space. objectives include precise studies origin dark matter, antimatter, and cosmic rays as well exploration new phenomena. Following 16-year period construction testing, precursor flight Shuttle, AMS was installed ISS May 19, 2011. In this report we present results based 120 billion charged ray events up...
We report the observation of new properties primary cosmic rays He, C, and O measured in rigidity (momentum/charge) range 2 GV to 3 TV with 90×10^{6} helium, 8.4×10^{6} carbon, 7.0×10^{6} oxygen nuclei collected by Alpha Magnetic Spectrometer (AMS) during first five years operation. Above 60 GV, these three spectra have identical dependence. They all deviate from a single power law above 200 harden an way.
Precision measurements of cosmic ray positrons are presented up to 1 TeV based on 1.9 million collected by the Alpha Magnetic Spectrometer International Space Station. The positron flux exhibits complex energy dependence. Its distinctive properties (a) a significant excess starting from 25.2±1.8 GeV compared lower-energy, power-law trend, (b) sharp dropoff above 284+91−64 GeV, (c) in entire range is well described sum term associated with produced collision rays, which dominates at low...
We report on the observation of new properties secondary cosmic rays Li, Be, and B measured in rigidity (momentum per unit charge) range 1.9 GV to 3.3 TV with a total 5.4×10^{6} nuclei collected by AMS during first five years operation aboard International Space Station. The Li fluxes have an identical dependence above 7 all three 30 Li/Be flux ratio 2.0±0.1. deviate from single power law 200 way. This behavior has also been observed measurement primary He, C, O but dependences are...
Precision results on cosmic-ray electrons are presented in the energy range from 0.5 GeV to 1.4 TeV based $28.1\ifmmode\times\else\texttimes\fi{}{10}^{6}$ collected by Alpha Magnetic Spectrometer International Space Station. In entire electron and positron spectra have distinctly different magnitudes dependences. The flux exhibits a significant excess starting $42.{1}_{\ensuremath{-}5.2}^{+5.4}\text{ }\text{ }\mathrm{GeV}$ compared lower trends, but nature of this is above...
We present results over an 11-year Solar cycle of cosmic antiprotons based on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mn>1.1</a:mn><a:mo>×</a:mo><a:msup><a:mn>10</a:mn><a:mn>6</a:mn></a:msup></a:math> events in the rigidity range from 1.00 to 41.9 GV. The <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mover accent="true"><c:mi>p</c:mi><c:mo stretchy="false">¯</c:mo></c:mover></c:math> fluxes exhibit distinct properties. magnitude...
We present the precision measurement from May 2011 to 2017 (79 Bartels rotations) of proton fluxes at rigidities 1 60 GV and helium 1.9 based on a total 1×10^{9} events collected with Alpha Magnetic Spectrometer aboard International Space Station. This is in solar cycle 24, which has maximum April 2014. observed that, below 40 GV, flux show nearly identical fine structures both time relative amplitude. The amplitudes decrease increasing rigidity vanish above GV. are reduced during period,...
We report the observation of new properties primary iron (Fe) cosmic rays in rigidity range 2.65 GV to 3.0 TV with 0.62×106 nuclei collected by Alpha Magnetic Spectrometer experiment on International Space Station. Above 80.5 dependence ray Fe flux is identical He, C, and O fluxes, Fe/O ratio being constant at 0.155±0.006. This shows that unexpectedly belong same class which different from Ne, Mg, Si class.Received 2 October 2020Revised 22 November 2020Accepted 9 December...
We present high-statistics, precision measurements of the detailed time and energy dependence primary cosmic-ray electron flux positron over 79 Bartels rotations from May 2011 to 2017 in range 1 50 GeV. For first time, charge-sign dependent modulation during solar maximum has been investigated detail by leptons alone. Based on 23.5×10^{6} events, we report observation short-term structures timescale months coincident both flux. These are not visible e^{+}/e^{-} ratio. The across polarity...
A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2 GV to 3.3 TV based on 2.2×10^{6} events is presented. The detailed dependence spectral index presented for first time. rapidly hardens at high rigidities and becomes identical indices primary He, C, O cosmic rays above ∼700 GV. We observed that Φ_{N} can be as sum its component Φ_{N}^{P} secondary Φ_{N}^{S}, Φ_{N}=Φ_{N}^{P}+Φ_{N}^{S}, we found well described by weighted oxygen Φ_{O} (primary rays)...
We report the observation of new properties primary cosmic rays, neon (Ne), magnesium (Mg), and silicon (Si), measured in rigidity range 2.15 GV to 3.0 TV with 1.8×10^{6} Ne, 2.2×10^{6} Mg, 1.6×10^{6} Si nuclei collected by Alpha Magnetic Spectrometer experiment on International Space Station. The Ne Mg spectra have identical dependence above 3.65 GV. three 86.5 GV, deviate from a single power law 200 harden an way. Unexpectedly, rays is different He, C, O. This shows that O are two classes rays.
We present the precision measurement of daily proton fluxes in cosmic rays from May 20, 2011 to October 29, 2019 (a total 2824 days or 114 Bartels rotations) rigidity interval 1 100 GV based on 5.5×10^{9} protons collected with Alpha Magnetic Spectrometer aboard International Space Station. The exhibit variations multiple timescales. From 2014 2018, we observed recurrent flux a period 27 days. Shorter periods 9 and 13.5 are 2016. strength all three periodicities changes time rigidity....
Precision measurements by the Alpha Magnetic Spectrometer (AMS) on International Space Station of ^{3}He and ^{4}He fluxes are presented. The based 100 million nuclei in rigidity range from 2.1 to 21 GV 18 1.9 15 collected May 2011 November 2017. We observed that exhibit nearly identical variations with time. relative magnitude decreases increasing rigidity. dependence ^{3}He/^{4}He flux ratio is measured for first Below 4 GV, was found have a significant long-term time dependence. Above be...
We present the precision measurement of 2824 daily helium fluxes in cosmic rays from May 20, 2011 to October 29, 2019 rigidity interval 1.71 100 GV based on 7.6×10^{8} nuclei collected with Alpha Magnetic Spectrometer (AMS) aboard International Space Station. The flux and proton ratio exhibit variations multiple timescales. In nearly all time intervals 2014 2018, we observed recurrent a period 27 days. Shorter periods 9 days 13.5 are 2016. strength three periodicities changes rigidity....
We present the precision measurements of 11 years daily cosmic electron fluxes in rigidity interval from 1.00 to 41.9 GV based on 2.0×10^{8} electrons collected with Alpha Magnetic Spectrometer (AMS) aboard International Space Station. The exhibit variations multiple timescales. Recurrent flux periods 27 days, 13.5 and 9 days are observed. find that show distinctly different time proton fluxes. Remarkably, a hysteresis between is observed significance greater than 6σ at rigidities below 8.5...
Precision measurements by the Alpha Magnetic Spectrometer (AMS) on International Space Station of deuteron (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>D</a:mi></a:mrow></a:math>) flux are presented. The based <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mrow><c:mn>21</c:mn><c:mo>×</c:mo><c:msup><c:mrow><c:mn>10</c:mn></c:mrow><c:mrow><c:mn>6</c:mn></c:mrow></c:msup></c:mrow></c:math> <e:math...
We report the properties of precision time structures cosmic nuclei He, Li, Be, B, C, N, and O fluxes over an 11-year solar cycle from May 2011 to November 2022 in rigidity range 1.92 60.3 GV. The show similar but not identical variations with amplitudes decreasing increasing rigidity. In particular, below 3.64 GV B fluxes, 2.15 are significantly less affected by modulation than He flux. observe that these differences linearly correlated spectral indices fluxes. This shows, a...
Precise knowledge of the charge and rigidity dependence secondary cosmic ray fluxes secondary-to-primary flux ratios is essential in understanding propagation. We report properties heavy fluorine F R range 2.15 GV to 2.9 TV based on 0.29 million events collected by Alpha Magnetic Spectrometer experiment International Space Station. The spectrum deviates from a single power law above 200 GV. heavier F/Si ratio distinctly different lighter B/O (or B/C) dependence. In particular, 10 GV, F/SiB/O...
We report the properties of sodium (Na) and aluminum (Al) cosmic rays in rigidity range 2.15 GV to 3.0 TV based on 0.46 million 0.51 nuclei collected by Alpha Magnetic Spectrometer experiment International Space Station. found that Na Al, together with nitrogen (N), belong a distinct ray group. In this group, we observe that, similar N flux, both flux Al are well described sums primary component (proportional silicon flux) secondary fluorine flux). The fraction increases for N, Na, fluxes...
Abstract Stokes' hypothesis allows for the frequent neglect of bulk viscosity term related to fluid dilation effects on viscous stress tensor in Newtonian flows. Configurations which this is not valid widely exist, but they are always well distinguished. Meanwhile, it was pointed out earlier that original Navier-Stokes equations may be incomplete, leading development \textit{volume diffusion} hydrodynamics. This article recalls form when (or actual density variation) properly accounted...
We report the properties of primary cosmic-ray sulfur (S) in rigidity range 2.15 GV to 3.0 TV based on 0.38×10^{6} nuclei collected by Alpha Magnetic Spectrometer experiment (AMS). observed that above 90 dependence S flux is identical Ne-Mg-Si fluxes, which different from He-C-O-Fe fluxes. found that, similar N, Na, and Al cosmic rays, over entire range, traditional rays S, Ne, Mg, C all have sizeable secondary components, Mg fluxes are well described weighted sum silicon fluorine flux,...
We present the precision measurements of 11 years daily cosmic positron fluxes in rigidity range from 1.00 to 41.9 GV based on 3.4×10^{6} positrons collected with Alpha Magnetic Spectrometer (AMS) aboard International Space Station. The show distinctly different time variations electron at short and long timescales. A hysteresis between is observed a significance greater than 5σ rigidities below 8.5 GV. On contrary, proton similar variation. Remarkably, we found that are modulated more for 7...
We investigate a model for microgas-flows consisting of the Navier–Stokes equations extended to include description molecular collisions with solid-boundaries together first- and second-order velocity-slip boundary conditions. By considering affected by boundaries in gas flows, we capture some near-wall effects that conventional linear stress-/strain-rate relationship are unable describe. Our is expressed through geometry-dependent mean-free-path yielding new viscosity expression, which...
Different nonkinetic approaches are adopted in this paper towards theoretically predicting the experimentally observed phenomenon of enhanced mass flow rates accompanying pressure-driven rarefied gas flows through microchannels. Our analysis utilizes a full set mechanically consistent volume-diffusion hydrodynamic equations, allowing complete, closed-form, analytical solutions to class problems. As an integral part analysis, existing experimental data pertaining subatmospheric pressure...