The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
P. B. Schwinberg - One of the best experts on this subject based on the ideXlab platform.
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ultraprecise Atomic Mass measurement of the alpha particle and 4he
Physical Review Letters, 2004Co-Authors: R S Van Dyck, S. L. Zafonte, S Van Liew, David B Pinegar, P. B. SchwinbergAbstract:The Atomic Masses of the alpha particle and 4He have been measured by means of a Penning trap Mass spectrometer which utilizes a frequency-shift detector to observe single-ion cyclotron resonances in an extremely stable 6.0 T magnetic field. The present resolution of this instrument approaches 0.01 ppb [10 ppt (parts per trillion)] and is limited primarily by the effective stability (<5 ppt/h) of the magnet over hundreds of hours of observation. The leading systematic shift [at -202(9) ppt] is due to the image charge located in the trap electrodes. The new value for the Atomic Mass of the alpha particle is 4 001 506 179.147(64) nu and the corresponding value for the Mass of 4He is 4 002 603 254.153(64) nu (nu=10(-9) u). The 16 ppt uncertainty is at least 20 times smaller than any previous determination.
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Determination of the Electron's Atomic Mass and the Proton/Electron Mass Ratio via Penning Trap Mass Spectroscopy
Physical review letters, 1995Co-Authors: D.l. Farnham, Robert S. Van Dyck, P. B. SchwinbergAbstract:Accuracy of the electron's Atomic Mass has been improved tenfold by comparing cyclotron frequencies of electrons and single ${\mathrm{C}}^{6+}$ ions alternately confined to the same uniform magnetic field in a Penning trap. Cyclotron resonances are observed via frequency shifts in the particle's continuously monitored harmonic motion parallel to the field. Field instability and relativity cause, respectively, the leading statistical and systematic errors. Combining the electron's Atomic Mass ${M}_{e}=0.0005485799111(12)$ u with the proton's yields the Mass ratio $\frac{{m}_{p}}{{m}_{e}}=1836.1526665(40)$.
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determination of the electron s Atomic Mass and the proton electron Mass ratio via penning trap Mass spectroscopy
Physical Review Letters, 1995Co-Authors: D.l. Farnham, Robert S. Van Dyck, P. B. SchwinbergAbstract:Accuracy of the electron's Atomic Mass has been improved tenfold by comparing cyclotron frequencies of electrons and single ${\mathrm{C}}^{6+}$ ions alternately confined to the same uniform magnetic field in a Penning trap. Cyclotron resonances are observed via frequency shifts in the particle's continuously monitored harmonic motion parallel to the field. Field instability and relativity cause, respectively, the leading statistical and systematic errors. Combining the electron's Atomic Mass ${M}_{e}=0.0005485799111(12)$ u with the proton's yields the Mass ratio $\frac{{m}_{p}}{{m}_{e}}=1836.1526665(40)$.
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Precision Mass measurements in the UW-PTMS and the electron's "Atomic Mass"
Physica Scripta, 1995Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The Penning trap Mass spectrometer at the University of Washington is described along with the relevant detection mechanisms and the systematic shifts associated with the finite energies in the normal modes of the trapped particle. The cyclotron frequency for the particle-of-interest is compared with the corresponding frequency of a single trapped carbon ion (usually C6+). Upon correcting for lost electrons and their binding energies, the relative Mass ratio then becomes the Atomic Mass for the particle-of-interest. As a recent example, the value of the electron's "Atomic Mass" has been measured to be Me = 0.000 548 579 911 7(17) u and the corresponding proton–electron Mass ratio becomes mp/me = 1836.152 664 6 (58).
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Proton/electron Mass ratio and the electron's "Atomic Mass"
IEEE Transactions on Instrumentation and Measurement, 1995Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The UW Penning trap Mass spectrometer has been used to improve the values for the electron's Atomic Mass and the proton-electron Mass ratio. The cyclotron frequency of small clouds of /spl les/15 electrons is compared with the cyclotron frequency of a single trapped carbon ion (C/sup 6+/) in order to determine their relative Mass ratio. In these comparisons, a relatively uniform magnetic field is used in order to assure that each particle sees (on the average) the same field. During systematic studies, the trapping potential was changed by more than a factor of two for the electron. In addition, measurements were taken versus axial and cyclotron drive power as well as the size of the electron cloud. Since the detection mechanism is through the nonharmonic content of the trapping potential, this too was varied. Upon correcting for the lost electrons in carbon, the comparison directly yields M/sub e/=0.000 548 579 911 7(1 7) u. Using the accepted value for the proton's Atomic Mass, we determine m/sub p//m/sub e/=1836.152 6636(58). These values are limited primarily by the present stability of the magnetic field. >
D.l. Farnham - One of the best experts on this subject based on the ideXlab platform.
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Determination of the Electron's Atomic Mass and the Proton/Electron Mass Ratio via Penning Trap Mass Spectroscopy
Physical review letters, 1995Co-Authors: D.l. Farnham, Robert S. Van Dyck, P. B. SchwinbergAbstract:Accuracy of the electron's Atomic Mass has been improved tenfold by comparing cyclotron frequencies of electrons and single ${\mathrm{C}}^{6+}$ ions alternately confined to the same uniform magnetic field in a Penning trap. Cyclotron resonances are observed via frequency shifts in the particle's continuously monitored harmonic motion parallel to the field. Field instability and relativity cause, respectively, the leading statistical and systematic errors. Combining the electron's Atomic Mass ${M}_{e}=0.0005485799111(12)$ u with the proton's yields the Mass ratio $\frac{{m}_{p}}{{m}_{e}}=1836.1526665(40)$.
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determination of the electron s Atomic Mass and the proton electron Mass ratio via penning trap Mass spectroscopy
Physical Review Letters, 1995Co-Authors: D.l. Farnham, Robert S. Van Dyck, P. B. SchwinbergAbstract:Accuracy of the electron's Atomic Mass has been improved tenfold by comparing cyclotron frequencies of electrons and single ${\mathrm{C}}^{6+}$ ions alternately confined to the same uniform magnetic field in a Penning trap. Cyclotron resonances are observed via frequency shifts in the particle's continuously monitored harmonic motion parallel to the field. Field instability and relativity cause, respectively, the leading statistical and systematic errors. Combining the electron's Atomic Mass ${M}_{e}=0.0005485799111(12)$ u with the proton's yields the Mass ratio $\frac{{m}_{p}}{{m}_{e}}=1836.1526665(40)$.
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Precision Mass measurements in the UW-PTMS and the electron's "Atomic Mass"
Physica Scripta, 1995Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The Penning trap Mass spectrometer at the University of Washington is described along with the relevant detection mechanisms and the systematic shifts associated with the finite energies in the normal modes of the trapped particle. The cyclotron frequency for the particle-of-interest is compared with the corresponding frequency of a single trapped carbon ion (usually C6+). Upon correcting for lost electrons and their binding energies, the relative Mass ratio then becomes the Atomic Mass for the particle-of-interest. As a recent example, the value of the electron's "Atomic Mass" has been measured to be Me = 0.000 548 579 911 7(17) u and the corresponding proton–electron Mass ratio becomes mp/me = 1836.152 664 6 (58).
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Proton/electron Mass ratio and the electron's "Atomic Mass"
IEEE Transactions on Instrumentation and Measurement, 1995Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The UW Penning trap Mass spectrometer has been used to improve the values for the electron's Atomic Mass and the proton-electron Mass ratio. The cyclotron frequency of small clouds of /spl les/15 electrons is compared with the cyclotron frequency of a single trapped carbon ion (C/sup 6+/) in order to determine their relative Mass ratio. In these comparisons, a relatively uniform magnetic field is used in order to assure that each particle sees (on the average) the same field. During systematic studies, the trapping potential was changed by more than a factor of two for the electron. In addition, measurements were taken versus axial and cyclotron drive power as well as the size of the electron cloud. Since the detection mechanism is through the nonharmonic content of the trapping potential, this too was varied. Upon correcting for the lost electrons in carbon, the comparison directly yields M/sub e/=0.000 548 579 911 7(1 7) u. Using the accepted value for the proton's Atomic Mass, we determine m/sub p//m/sub e/=1836.152 6636(58). These values are limited primarily by the present stability of the magnetic field. >
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Atomic Mass measurements of H, He, and C, yielding neutron separation energies
Bulletin of the American Physical Society, 1993Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The Penning trap Mass spectrometer (PTMS) has again been used to measure various light elements to a precision that exceeds 0.5 parts per billion. In addition, some isotopes of a given element may be combined with the new value for the neutron`s Atomic Mass = 1,008,664,918.66(256) nu to yield neutron separation energies S{sub n} according to: S{sub n}({sup A}X) = m{sub n} + M({sup A{minus}1}X) {minus} M({sup A}X).
R S Van Dyck - One of the best experts on this subject based on the ideXlab platform.
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Ultra-precise single-ion Atomic Mass measurements on deuterium and helium-3
Metrologia, 2015Co-Authors: S. L. Zafonte, R S Van DyckAbstract:The former University of Washington Penning Trap Mass Spectrometer (UW-PTMS), now located at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany, was used in the decade before the move to determine new values for the deuteron Atomic Mass, M (2H+) = 2.013 553 212 745(40) u, and the deuterium Atomic Mass, M (2H) = 2.014 101 778 052(40) u, both of which are now more than an order-of-magnitude more accurate than the previous best 1994-MIT measurements of these quantities. The new value for the deuteron's Mass can then be used with the accepted 2010-CODATA proton Mass and the most recent 1999-measurement of the 2.2 MeV gamma-ray binding energy of the deuteron to refine the neutron's Mass to mn = 1.008 664 916 018(435) u which has about half the uncertainty relative to the value computed using that previous 1994-MIT deuterium measurement. As a result, further improvements of mn must now come from a more accurate determination of the wavelength of this gamma ray.In this same period of time, this spectrometer has also been used to determine new values for the helion Atomic Mass, M (3He2+) = 3.014 932 246 668(43) u, and the neutral helium-3 Atomic Mass, M (3He) = 3.016 029 321 675(43) u, which are both about 60 times more accurate than the 2006-SMILETRAP measurements, but disagree with the 4.4-times less-accurate 2015-Florida-State measurements by 0.76 nu. It is expected that these helium-3 results will be used in the future 3H/3He Mass ratio (to be determined by the Heidelberg, Germany version of the old UW-PTMS) in order to generate a more accurate value for the tritium Atomic Mass.
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ultraprecise Atomic Mass measurement of the alpha particle and 4he
Physical Review Letters, 2004Co-Authors: R S Van Dyck, S. L. Zafonte, S Van Liew, David B Pinegar, P. B. SchwinbergAbstract:The Atomic Masses of the alpha particle and 4He have been measured by means of a Penning trap Mass spectrometer which utilizes a frequency-shift detector to observe single-ion cyclotron resonances in an extremely stable 6.0 T magnetic field. The present resolution of this instrument approaches 0.01 ppb [10 ppt (parts per trillion)] and is limited primarily by the effective stability (<5 ppt/h) of the magnet over hundreds of hours of observation. The leading systematic shift [at -202(9) ppt] is due to the image charge located in the trap electrodes. The new value for the Atomic Mass of the alpha particle is 4 001 506 179.147(64) nu and the corresponding value for the Mass of 4He is 4 002 603 254.153(64) nu (nu=10(-9) u). The 16 ppt uncertainty is at least 20 times smaller than any previous determination.
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Precision Mass measurements in the UW-PTMS and the electron's "Atomic Mass"
Physica Scripta, 1995Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The Penning trap Mass spectrometer at the University of Washington is described along with the relevant detection mechanisms and the systematic shifts associated with the finite energies in the normal modes of the trapped particle. The cyclotron frequency for the particle-of-interest is compared with the corresponding frequency of a single trapped carbon ion (usually C6+). Upon correcting for lost electrons and their binding energies, the relative Mass ratio then becomes the Atomic Mass for the particle-of-interest. As a recent example, the value of the electron's "Atomic Mass" has been measured to be Me = 0.000 548 579 911 7(17) u and the corresponding proton–electron Mass ratio becomes mp/me = 1836.152 664 6 (58).
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Proton/electron Mass ratio and the electron's "Atomic Mass"
IEEE Transactions on Instrumentation and Measurement, 1995Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The UW Penning trap Mass spectrometer has been used to improve the values for the electron's Atomic Mass and the proton-electron Mass ratio. The cyclotron frequency of small clouds of /spl les/15 electrons is compared with the cyclotron frequency of a single trapped carbon ion (C/sup 6+/) in order to determine their relative Mass ratio. In these comparisons, a relatively uniform magnetic field is used in order to assure that each particle sees (on the average) the same field. During systematic studies, the trapping potential was changed by more than a factor of two for the electron. In addition, measurements were taken versus axial and cyclotron drive power as well as the size of the electron cloud. Since the detection mechanism is through the nonharmonic content of the trapping potential, this too was varied. Upon correcting for the lost electrons in carbon, the comparison directly yields M/sub e/=0.000 548 579 911 7(1 7) u. Using the accepted value for the proton's Atomic Mass, we determine m/sub p//m/sub e/=1836.152 6636(58). These values are limited primarily by the present stability of the magnetic field. >
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Atomic Mass measurements of H, He, and C, yielding neutron separation energies
Bulletin of the American Physical Society, 1993Co-Authors: R S Van Dyck, D.l. Farnham, P. B. SchwinbergAbstract:The Penning trap Mass spectrometer (PTMS) has again been used to measure various light elements to a precision that exceeds 0.5 parts per billion. In addition, some isotopes of a given element may be combined with the new value for the neutron`s Atomic Mass = 1,008,664,918.66(256) nu to yield neutron separation energies S{sub n} according to: S{sub n}({sup A}X) = m{sub n} + M({sup A{minus}1}X) {minus} M({sup A}X).
Gang Chen - One of the best experts on this subject based on the ideXlab platform.
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stronger phonon scattering by larger differences in Atomic Mass and size in p type half heuslers hf1 xtixcosb0 8sn0 2
Energy and Environmental Science, 2012Co-Authors: Xiao Yan, Weishu Liu, Hui Wang, Shuo Chen, Junichiro Shiomi, Keivan Esfarjani, Hengzhi Wang, Dezhi Wang, Gang ChenAbstract:High lattice thermal conductivity has been the bottleneck for further improvement of the thermoelectric figure-of-merit (ZT) of half-Heuslers (HHs) Hf1−xZrxCoSb0.8Sn0.2. Theoretically, the lattice thermal conductivity can be reduced by exploring larger differences in the Atomic Mass and size in the crystal structure, leading to higher ZT. In this paper, we experimentally demonstrated that a lower thermal conductivity in p-type half-Heuslers can be achieved when Ti is used to replace Zr, i.e., Hf1−xTixCoSb0.8Sn0.2, due to larger differences in the Atomic Mass and size between Hf and Ti compared with Hf and Zr. The highest ZT peak, ∼1.0 at 800 °C, in the Hf1−xTixCoSb0.8Sn0.2 (x = 0.1, 0.2, 0.3, and 0.5) system was achieved using Hf0.8Ti0.2CoSb0.8Sn0.2, which makes this material useful in power generation applications.
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Stronger phonon scattering by larger differences in Atomic Mass and size in p-type half-Heuslers Hf1−xTixCoSb0.8Sn0.2
Energy & Environmental Science, 2012Co-Authors: Xiao Yan, Weishu Liu, Hui Wang, Shuo Chen, Junichiro Shiomi, Keivan Esfarjani, Hengzhi Wang, Dezhi Wang, Gang Chen, Zhifeng RenAbstract:High lattice thermal conductivity has been the bottleneck for further improvement of the thermoelectric figure-of-merit (ZT) of half-Heuslers (HHs) Hf1−xZrxCoSb0.8Sn0.2. Theoretically, the lattice thermal conductivity can be reduced by exploring larger differences in the Atomic Mass and size in the crystal structure, leading to higher ZT. In this paper, we experimentally demonstrated that a lower thermal conductivity in p-type half-Heuslers can be achieved when Ti is used to replace Zr, i.e., Hf1−xTixCoSb0.8Sn0.2, due to larger differences in the Atomic Mass and size between Hf and Ti compared with Hf and Zr. The highest ZT peak, ∼1.0 at 800 °C, in the Hf1−xTixCoSb0.8Sn0.2 (x = 0.1, 0.2, 0.3, and 0.5) system was achieved using Hf0.8Ti0.2CoSb0.8Sn0.2, which makes this material useful in power generation applications.
Junichiro Shiomi - One of the best experts on this subject based on the ideXlab platform.
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stronger phonon scattering by larger differences in Atomic Mass and size in p type half heuslers hf1 xtixcosb0 8sn0 2
Energy and Environmental Science, 2012Co-Authors: Xiao Yan, Weishu Liu, Hui Wang, Shuo Chen, Junichiro Shiomi, Keivan Esfarjani, Hengzhi Wang, Dezhi Wang, Gang ChenAbstract:High lattice thermal conductivity has been the bottleneck for further improvement of the thermoelectric figure-of-merit (ZT) of half-Heuslers (HHs) Hf1−xZrxCoSb0.8Sn0.2. Theoretically, the lattice thermal conductivity can be reduced by exploring larger differences in the Atomic Mass and size in the crystal structure, leading to higher ZT. In this paper, we experimentally demonstrated that a lower thermal conductivity in p-type half-Heuslers can be achieved when Ti is used to replace Zr, i.e., Hf1−xTixCoSb0.8Sn0.2, due to larger differences in the Atomic Mass and size between Hf and Ti compared with Hf and Zr. The highest ZT peak, ∼1.0 at 800 °C, in the Hf1−xTixCoSb0.8Sn0.2 (x = 0.1, 0.2, 0.3, and 0.5) system was achieved using Hf0.8Ti0.2CoSb0.8Sn0.2, which makes this material useful in power generation applications.
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Stronger phonon scattering by larger differences in Atomic Mass and size in p-type half-Heuslers Hf1−xTixCoSb0.8Sn0.2
Energy & Environmental Science, 2012Co-Authors: Xiao Yan, Weishu Liu, Hui Wang, Shuo Chen, Junichiro Shiomi, Keivan Esfarjani, Hengzhi Wang, Dezhi Wang, Gang Chen, Zhifeng RenAbstract:High lattice thermal conductivity has been the bottleneck for further improvement of the thermoelectric figure-of-merit (ZT) of half-Heuslers (HHs) Hf1−xZrxCoSb0.8Sn0.2. Theoretically, the lattice thermal conductivity can be reduced by exploring larger differences in the Atomic Mass and size in the crystal structure, leading to higher ZT. In this paper, we experimentally demonstrated that a lower thermal conductivity in p-type half-Heuslers can be achieved when Ti is used to replace Zr, i.e., Hf1−xTixCoSb0.8Sn0.2, due to larger differences in the Atomic Mass and size between Hf and Ti compared with Hf and Zr. The highest ZT peak, ∼1.0 at 800 °C, in the Hf1−xTixCoSb0.8Sn0.2 (x = 0.1, 0.2, 0.3, and 0.5) system was achieved using Hf0.8Ti0.2CoSb0.8Sn0.2, which makes this material useful in power generation applications.