The alkali-atom density measurement method based on light absorption is highly suitable for a spin-exchange relaxationfree(SERF)atomic magnetometer because of its high-precision measurement and complete nonmagnetic in...The alkali-atom density measurement method based on light absorption is highly suitable for a spin-exchange relaxationfree(SERF)atomic magnetometer because of its high-precision measurement and complete nonmagnetic interference.In this study,the optical rotation angle detection system based on polarization balance detection is utilized to realize the alkali-atom density real-time measurement without affecting magnetic field measurement.We discovered that there exists an optimal frequency detuning of the probe light,which offers the highest sensitivity in alkali-atom density measurement and the lowest susceptibility to temperature fluctuations in terms of the scale factor.In contrast to conventional light absorption measurements based on pump light,this method demonstrated a threefold improvement in alkali-atom density measurement sensitivity while remaining immune to ambient magnetic fields and incident light intensity fluctuations.Furthermore,we utilized this method to achieve closed-loop temperature control with an accuracy of 0.04℃.展开更多
A transverse relaxation determination of spin-exchange relaxation free （SERF） magnetometer based on polarization modulation technique is proposed. Compared with the radio-frequency （RF） excitation and light intens...A transverse relaxation determination of spin-exchange relaxation free （SERF） magnetometer based on polarization modulation technique is proposed. Compared with the radio-frequency （RF） excitation and light intensity excitation meth- ods used in SERF magnetometer, the light polarization modulation method has a high stability in low-frequency range, which indicates a more accurate transverse relaxation measurement.展开更多
Since 1959, the freed serfs in Tibet have experienced tremendous improvements,reflected with changes in the family of the82-year-old Dawa.Dawa lives in the Khezang Village of Lhoka City in the Tibet Autonomous Region ...Since 1959, the freed serfs in Tibet have experienced tremendous improvements,reflected with changes in the family of the82-year-old Dawa.Dawa lives in the Khezang Village of Lhoka City in the Tibet Autonomous Region and is one of the few former Tibetan serfs still alive today in the region.Tibet practiced feudal serf system until 1959, and about one million serfs were freed since then.展开更多
The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the sur...The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_(H)), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole)> S_(H), the sequence of the shielding property is equilateral triangle >square > circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability.展开更多
WHEN we sat down facing each other, I could hardly believe this woman was the former Vice Chairman of the Tibet Autonomous Regional People's Government, now Vice-Secretary of the autonomous regional Committee of t...WHEN we sat down facing each other, I could hardly believe this woman was the former Vice Chairman of the Tibet Autonomous Regional People's Government, now Vice-Secretary of the autonomous regional Committee of the CPC and its committee of the CPPCC. This plain looking and soberly dressed woman is Pasang, a high official grown from a serf. Looking at her weather-worn face, I guessed her age. What surprised me展开更多
文摘The alkali-atom density measurement method based on light absorption is highly suitable for a spin-exchange relaxationfree(SERF)atomic magnetometer because of its high-precision measurement and complete nonmagnetic interference.In this study,the optical rotation angle detection system based on polarization balance detection is utilized to realize the alkali-atom density real-time measurement without affecting magnetic field measurement.We discovered that there exists an optimal frequency detuning of the probe light,which offers the highest sensitivity in alkali-atom density measurement and the lowest susceptibility to temperature fluctuations in terms of the scale factor.In contrast to conventional light absorption measurements based on pump light,this method demonstrated a threefold improvement in alkali-atom density measurement sensitivity while remaining immune to ambient magnetic fields and incident light intensity fluctuations.Furthermore,we utilized this method to achieve closed-loop temperature control with an accuracy of 0.04℃.
基金Project supported by the National Natural Science Foundation of China(Grant No.61227902)the National Key R&D Program of China(Grant No.2017YFB0503100)the Natural Science Foundation of Beijing Municipality,China(Grant No.4162038)
文摘A transverse relaxation determination of spin-exchange relaxation free （SERF） magnetometer based on polarization modulation technique is proposed. Compared with the radio-frequency （RF） excitation and light intensity excitation meth- ods used in SERF magnetometer, the light polarization modulation method has a high stability in low-frequency range, which indicates a more accurate transverse relaxation measurement.
文摘Since 1959, the freed serfs in Tibet have experienced tremendous improvements,reflected with changes in the family of the82-year-old Dawa.Dawa lives in the Khezang Village of Lhoka City in the Tibet Autonomous Region and is one of the few former Tibetan serfs still alive today in the region.Tibet practiced feudal serf system until 1959, and about one million serfs were freed since then.
基金supported by the Key Projects of the National Natural Science Foundation of China (Grant No. 51535002)the Programme of Introducing Talents of Discipline to Universities (Grant No. D17021)。
文摘The shielding property of cylinder with circular, square, and equilateral triangle holes was investigated by finite element analysis(FEA). The hole area(S_(hole)) plays an important role in magnetic circuit on the surface of cylinder. When Sholeis less than the critical area(S_(H)), cylinder with three shapes of holes obtained the same remanent magnetization inside,indicating that the shielding property is unaffected by the shape of the hole. Hence, high-permeability material is the major path of the magnetic field. On the condition of S_(hole)> S_(H), the sequence of the shielding property is equilateral triangle >square > circular, resulting from magnetoresistance of leakage flux in air dielectric. Besides, the anisotropy of shielding property caused by hole structural differences of the cylinder is evaluated. We find that a good shielding effectiveness is gained in the radial direction, compared with the axis direction. This research focuses on providing a theoretical support for the design of magnetic shield and improvement on the magnetic shielding ability.
文摘WHEN we sat down facing each other, I could hardly believe this woman was the former Vice Chairman of the Tibet Autonomous Regional People's Government, now Vice-Secretary of the autonomous regional Committee of the CPC and its committee of the CPPCC. This plain looking and soberly dressed woman is Pasang, a high official grown from a serf. Looking at her weather-worn face, I guessed her age. What surprised me
