Analysis of the light shift effect in the 87Rb frequencystandard

The ⁸⁷Rb cell frequency standard, optically pumped by a laser diode, is of great interest in the development of high-stability, short-term oscillators. We report the experiments performed on a rubidium-cell prototype aiming to evaluate the transfer of the laser and microwave noise to the hyperfine clock transition via the light-shift effect, which appears to be the main contribution to the observed short- and medium-term instabilities in this kind of a standard. Pulsed optical pumping is also examined in order to strongly reduce the light-shift effect: the experimental results show an improvement in medium term frequency stability     

X-ray and gamma ray intensity measurements in 141Ce and 170Tm decays

Relative intensities of X-rays and gamma rays in the decays of ¹⁴¹Ce and ¹⁷⁰Tm were precisely measured using a 28.27 mm² × 5.0 m vertical planar high purity Ge (HPGe) detector and a 28.27 mm² × 5.5 mm vertical Si(Li) detector. The intensities of the different X-rays measured in the decays of ¹⁴¹Ce and ¹⁷⁰Tm agree reasonably well with the results calculated using the formulation of Verma and Pal [1] in most of the cases. The measured value of the L_β1.3.4 X-ray intensity from ¹⁴¹Ce is found to differ considerably from the calculated value, which could be due to wrong values of some of the parameters used in the theoretical calculations.     

Study of the 87Rb maser with both ends pumping

Experiments on the ⁸⁷Rb maser with both ends pumping showed variations of the maximum output power versus cell temperature. The largest output power was 2.0×10^-10 W, and a preliminary measurement gave an improved short-term frequency stability. The results of the numerical calculations based on the density matrix formalism agreed qualitatively with the experiments     

Evaluated values of the decay characteristics of the beta-radiating actinides 233Th, 239U, 236Np, 236mNp, 238Np, and 239Np

New estimated values of the decay and radiation characteristics of the radionuclides ²³³Th, ²³⁹U, ²³⁶Np, ^236m Np, ²³⁸Np, and ²³⁹Np obtained in light of information published in 2009 are presented.     

Er3+掺杂的 MFT玻璃材料2H11/2、4S3/2→4I15/2荧光性质

计算了Er     

Progress in the realization of a frequency standard at 192.1 THz(1560.5 nm) using 87Rb D2-line and second harmonicgeneration

Second harmonic generation of a 192.1 THz semiconductor distributed feedback (DFB) laser is achieved using a KNbO₃ crystal in a resonant ring cavity. Optical feedback from this cavity is used to stabilize the laser frequency and reduce its linewidth. A second harmonic power of 5.5 μW is generated with 38 mW incident on the cavity. We use the second harmonic signal to observe saturated absorption lines and orientation signals in rubidium vapor. Injection-locking of a 780 nm Fabry-Perot laser using the second harmonic signal is also demonstrated. With this scheme, we observe saturated absorption lines in rubidium     

Decay data measurements of 111In by 4πβ-γ coincidence spectrometry with a combination of a 4πβ counter and a Ge detector

The total internal conversion coefficients and the γ-intensities per decay of ¹¹¹In were determined directly from the slope-to-intercept ratio of the 4πβ-γ efficiency functions, which were measured by the 4πβ-γ coincidence spectrometry technique with a combination of a 4πβ gas flow counter and a Ge γ-ray spectrometer. The present results are in excellent agreement with Sparrmann's data, while there are considerable discrepancies as compared to the NDS evaluations.     

含铜离子玻璃中的混合碱效应的研究

本文研究了xCuBr-(40-x)NaBr-55P2O5-5CaO玻璃的混合碱效应。发现当Cu+/Cu++Na+≈0.5时,电导率达到最小值。电导率的最大值与最小值相差三个数量级。本文给出了电导率随温度、频率、成分的变化。这与一般混合碱效应的规律相类似。并用离子对模型对Cu+离子玻璃的混合碱效应进行了解释。     

3600m^3／h空分设备氮水预冷系统存在的三个问题

分析3600m^3／h空分设备氮水预冷系统存在的三个问题及原因，指出氮水预冷系统在操作中需注意的四个方面。     

The development of a method for the preparation of large amounts of 234Th-purified 238U-oxide

High purity ²³⁸U-oxide in amounts up to 60 g is required for capture cross-section measurements. The material needs to be purified for the ²³⁴Th daughter of ²³⁸U in order to reduce the natural γ background. It has been shown that 60 g of U₃O₈ can be purified by cation-exchange and retransformed in U₃O₈ in about 20 h. When the target is ready for use the ²³⁴Th content is 2% of the saturation value.     

Neutron polarisation from the reactions 13C(p,n013N and 15N(d,n0)16O

The neutron polarisation has been measured of the reaction ¹³C(p,n₀)¹³N for E_p = 6.9 MeV (E_n = 3.7 MeV) at θ_lab = 40° and of the reaction ¹⁵N(d,n₀)¹⁶O for E_d = 5.5 MeV (E_n = 15.3 MeV) at θ_lab = 20°.     

Functional possibilities of Ag- N 0AlGaAs- n +GaAs- n 0GaInAs-au structures with an isotype base region

We have considered the spectral characteristics of two-base structures with isotype heterojunctions and with Schottky and Mott barriers to the base regions and explained the features of the impurity and photovoltaic effects in two-base structures containing deep impurity levels of oxygen and intrinsic defects. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 1005–1009, September–October, 2008.     

205Tl and 19F nmr study of ionic motion and structure in a series of thallium pyrochlore ionic conductors

A series of defect pyrochlores of the type Tl_xNbO_2+xF_1?x have been studied for x = 0.5, 0.55, 0.6, 0.7, 0.8, and 1.0. Tl_0.5TaO_2.5F_0.5 was also examined. Both ²⁰⁵Tl and ¹⁹F resonances were studied from 120° to 540°K. The NMR data are related to the structure and to the motion of Tl⁺. The activation energy for the Tl⁺ motion measured by NMR is close to values determined by conductivity measurements.     

Uranium density and enrichment in fuel tubes determined from 232U and 235U γ-activities

Gamma spectroscopy is used to determine ²³⁵U density and enrichment in UAl fuel tubes containing recycled fuel. A collimated HPGe γ-detector views the tube surface, such that UAl disk volumes of 6.35 mm diameter and ～1.0 mm thickness are examined. The γ-activities from ²³²U and ²³⁵U, along with the tube design parameters, are used to deduce the attenuation-corrected results. Respective density and enrichment variations of <1% and <0.6 e% were measurable with 2000 s counting time per tube location. Such measurements are useful for certifying tube quality and characterizing problems associated with blending the UAl alloy.     

Ionic conductors NaxInxSn1−xS2: NMR study of 23Na and complex impedance measurements

The Na_xIn_xSn_1?xS₂ intercalation — substitution compounds have been studied by NMR of ²³Na and by complex impedance measurements. The obtained results — quadrupole splitting, T₁ relaxation times, hopping frequencies, diffusion coefficients, activation energies — are discussed and compared to those relative to homologous series. The role of some factors — such as the sodium environment geometry, the host structure covalency, and the amount of vacancies — is discussed.     

Decay of long-lived 129I

The decay of the long-lived fission nuclide ¹²⁹I was reinvestigated with a high-resolution HPGe detector. Accurate values of the energy and the absolute intensity of the 39.58 keV γ-rays are given together with Xe X-ray intensities. The K internal conversion coefficient of the M1 line is also deduced.     

4500m^3／h空分设备精氩塔冻结原因分析与处理

对合钢动力厂4500m^3／h空分设备精氩塔投产初期出现的反复冻结故障进行原因分析；在无法扒砂检修的情况下，采用非常规方法处理了故障。最后介绍了最终解决措施。     

Precision frequency measurement of the 2S1/2 2D5/2 transition of Sr+ with a 674-nmdiode laser locked to an ultrastable cavity

We have measured the frequency of the 5s ²S_1/2 -4d ²D_5/2 clock transition of a single Sr ion confined in a Paul trap. A diode laser locked to an ultrastable Fabry-Perot (F-P) cavity was used to probe the transition with a resolution of 3.5 kHz. The absolute frequency was determined from heterodyne measurements referenced to an iodine stabilized HeNe laser and a CO₂ laser yielding a value for the S-D transition of (444 779 043 963±30) kHz. This work could lead to the development of a new optical frequency standard at 674 nm     

Observation of a Sub-10-Hz Linewidth 88Sr+ 2S1/2–2D5/2 Clock Transition at 674 nm

In this paper, a pair of diode lasers at 674 nm, locked to two independent ultralow-expansion high-finesse cavities, have been characterized by monitoring the beat frequency between them. The individual laser linewidth of 1.4 Hz for a 3-s averaging time broadened to 4 Hz at 30 s. The relative frequency stability of the beat at 1s is 2.5 10^-15. One of the lasers has been used to interrogate the ⁸⁸Sr^{+ 2}Si_1/2-²D _5/2 transition at 674 nm, and a transition linewidth of 9 Hz has been observed     

武钢60000m^3／h制氧机流程与主冷型式的选择

对目前空分设备流程、主冷型式的安全性与节能性进行了分析和综合比较，阐述了武钢60000m^3／h制氧机选择外压缩流程和降膜式主冷的依据，提出了空分设备流程和主冷型式的选择原则。