Analysis of information sources in references of the Wikipedia article "Atomic clock" in English language version.
a narrow, laser-linewidth-limited spectral feature at 148.38219(4)stat(20)sys nm (2020407.3(5)stat(30)sys GHz) that decays with a lifetime of 568(13)stat(20)sys s. This feature is assigned to the excitation of the 229Th nuclear isomeric state, whose energy is found to be 8.355733(2)stat(10)</sys> eV in 229Th:LiSrAlF6.
The transition frequency between the I = 5/2 ground state and the I = 3/2 excited state is determined as: 𝜈Th = 1/6 (𝜈a + 2𝜈b + 2𝜈c + 𝜈d) = 2020407384335(2) kHz.
A half-life of 7±1 μs has been measured
Currently, the type B fractional uncertainty in NIST-F1 is 0.31×10−15 and is dominated by the uncertainty in the blackbody radiation (BBR) shift correction, which is 0.28×10−15 (this corresponds to a 1 degree uncertainty in the radiation environment as seen by the atoms in NIST-F1). To improve the performance of the NIST primary frequency standard, we sought to reduce the uncertainty due to the BBR effect. To accomplish this goal and to better understand the accepted model of the BBR shift, we developed NIST-F2, a laser-cooled Cs fountain primary frequency standard in which the microwave cavity structure and flight tube operate at cryogenic temperatures (80 K).
The nuclear resonance for the Th4+ ions in Th:CaF2 is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum.
a narrow, laser-linewidth-limited spectral feature at 148.38219(4)stat(20)sys nm (2020407.3(5)stat(30)sys GHz) that decays with a lifetime of 568(13)stat(20)sys s. This feature is assigned to the excitation of the 229Th nuclear isomeric state, whose energy is found to be 8.355733(2)stat(10)</sys> eV in 229Th:LiSrAlF6.
The transition frequency between the I = 5/2 ground state and the I = 3/2 excited state is determined as: 𝜈Th = 1/6 (𝜈a + 2𝜈b + 2𝜈c + 𝜈d) = 2020407384335(2) kHz.
A half-life of 7±1 μs has been measured
Currently, the type B fractional uncertainty in NIST-F1 is 0.31×10−15 and is dominated by the uncertainty in the blackbody radiation (BBR) shift correction, which is 0.28×10−15 (this corresponds to a 1 degree uncertainty in the radiation environment as seen by the atoms in NIST-F1). To improve the performance of the NIST primary frequency standard, we sought to reduce the uncertainty due to the BBR effect. To accomplish this goal and to better understand the accepted model of the BBR shift, we developed NIST-F2, a laser-cooled Cs fountain primary frequency standard in which the microwave cavity structure and flight tube operate at cryogenic temperatures (80 K).
The nuclear resonance for the Th4+ ions in Th:CaF2 is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum.
The transition frequency between the I = 5/2 ground state and the I = 3/2 excited state is determined as: 𝜈Th = 1/6 (𝜈a + 2𝜈b + 2𝜈c + 𝜈d) = 2020407384335(2) kHz.
A half-life of 7±1 μs has been measured
The nuclear resonance for the Th4+ ions in Th:CaF2 is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum.
a narrow, laser-linewidth-limited spectral feature at 148.38219(4)stat(20)sys nm (2020407.3(5)stat(30)sys GHz) that decays with a lifetime of 568(13)stat(20)sys s. This feature is assigned to the excitation of the 229Th nuclear isomeric state, whose energy is found to be 8.355733(2)stat(10)</sys> eV in 229Th:LiSrAlF6.
The transition frequency between the I = 5/2 ground state and the I = 3/2 excited state is determined as: 𝜈Th = 1/6 (𝜈a + 2𝜈b + 2𝜈c + 𝜈d) = 2020407384335(2) kHz.
A half-life of 7±1 μs has been measured
Currently, the type B fractional uncertainty in NIST-F1 is 0.31×10−15 and is dominated by the uncertainty in the blackbody radiation (BBR) shift correction, which is 0.28×10−15 (this corresponds to a 1 degree uncertainty in the radiation environment as seen by the atoms in NIST-F1). To improve the performance of the NIST primary frequency standard, we sought to reduce the uncertainty due to the BBR effect. To accomplish this goal and to better understand the accepted model of the BBR shift, we developed NIST-F2, a laser-cooled Cs fountain primary frequency standard in which the microwave cavity structure and flight tube operate at cryogenic temperatures (80 K).
A half-life of 7±1 μs has been measured
The nuclear resonance for the Th4+ ions in Th:CaF2 is measured at the wavelength 148.3821(5) nm, frequency 2020.409(7) THz, and the fluorescence lifetime in the crystal is 630(15) s, corresponding to an isomer half-life of 1740(50) s for a nucleus isolated in vacuum.
