First Sagittarius A* Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring

In a companion paper, we present the first spatially resolved polarized image of Sagittarius A* on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%–28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87*, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A* (equivalent to ≈46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow

Development of a Miniature High Resolution Electron Impact Ion Source Time-of-Flight Mass Spectrometer

常用的气体分析质谱仪使用四极杆质谱作为分析器,分辨率一般低于300,无法解决同质量数离子带来的干扰问题。本实验自行研制了一种小型高分辨气体分析质谱仪,它采用电子轰击离子源反射式飞行时间质量分析器。仪器腔体总长45 CM,在M/z 28的位置,质量分辨率达到3000(full WIdTH AT HAlf MAXIMuM,fWHM),实现了CO和n2的半峰谷分离;在M/z 69的位置,仪器分辨率达到5000(fWHM)。在直接大气压进样条件下,可以检测到空气中136XE(含量7.8μg/M3)和80kr(含量2.8μg/M3)。使用AdC采集时,仪器的动态范围为106。该仪器将作为高端气体质谱仪,应用于过程监测在线分析、环境有机挥发物研究、热分析质谱及催化反应监测等领域。Since gas analysis mass spectrometers usually use quadrupole as the mass analyzer,the resolution is typically less than 300,and the same mass ions interference problem cannot be solved.This study developed a high resolution gas analysis mass spectrometer.Electron impact ion source reflection time-of-flight mass analyzer has been designed and tested.The length of vacuum chamber is only 45 cm.Mass resolution of 3,000(Full width at half maximum,FWHM) has been achieved at m/z 28,as a result,CO and N2 can be separated at the half peak height.The best resolution of instrument can reach 5000(FWHM) at m/z 69.At the condition of direct ambient air sampling,136Xe(7.8 μg/m3) and 80Kr(2.8 μg/m3) can be detected.The dynamic range is up to 106 with fast ADC acquiring system.This instrument can be used as a high-end gas mass spectrometer and applied to on-line gas analysis for process monitoring,environmental organic volatile compounds research,thermal analysis mass spectrometry and catalytic reaction monitoring.中央高校科研业务费(No.2010121042)资助项

小型高分辨电子轰击离子源反射式飞行时间质谱仪的研制

常用的气体分析质谱仪使用四极杆质谱作为分析器,分辨率一般低于300,无法解决同质量数离子带来的干扰问题。本实验自行研制了一种小型高分辨气体分析质谱仪,它采用电子轰击离子源反射式飞行时间质量分析器。仪器腔体总长45 cm,在m/z 28的位置,质量分辨率达到3000（Full width at half maximum,FWHM）,实现了CO和N2的半峰谷分离;在m/z 69的位置,仪器分辨率达到5000（FWHM）。在直接大气压进样条件下,可以检测到空气中136Xe（含量7.8μg/m3）和80Kr（含量2.8μg/m3）。使用ADC采集时,仪器的动态范围为106。该仪器将作为高端气体质谱仪,应用于过程监测在线分析、环境有机挥发物研究、热分析质谱及催化反应监测等领域

小型高分辨电子轰击离子源反射式飞行时间质谱仪的研制

常用的气体分析质谱仪使用四极杆质谱作为分析器,分辨率一般低于300,无法解决同质量数离子带来的干扰问题。本实验自行研制了一种小型高分辨气体分析质谱仪,它采用电子轰击离子源反射式飞行时间质量分析器。仪器腔体总长45 cm,在m/z 28的位置,质量分辨率达到3000（Full width at half maximum,FWHM）,实现了CO和N2的半峰谷分离;在m/z 69的位置,仪器分辨率达到5000（FWHM）。在直接大气压进样条件下,可以检测到空气中136Xe（含量7.8μg/m3）和80Kr（含量2.8μg/m3）。使用ADC采集时,仪器的动态范围为106。该仪器将作为高端气体质谱仪,应用于过程监测在线分析、环境有机挥发物研究、热分析质谱及催化反应监测等领域

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies