SGR J1745-2900 is a magnetar near the Galactic center. X-ray observations of this source found a decreasing X-ray luminosity accompanied by an enhanced spindown rate. This negative correlation between X-ray luminosity...SGR J1745-2900 is a magnetar near the Galactic center. X-ray observations of this source found a decreasing X-ray luminosity accompanied by an enhanced spindown rate. This negative correlation between X-ray luminosity and spindown rate is hard to understand. The wind braking model of magnetars is employed to explain this puzzling spindown behavior. During the release of magnetic energy of magnetars, a system of particles may be generated. Some of these particles remain trapped in the magnetosphere and may contribute to the X-ray luminosity. The rest of the particles can flow out and take away the rotational energy of the central neutron star. A smaller polar cap angle will cause the decrease of X-ray luminosity and enhanced spindown rate of SGR J1745-2900. This magnetar is shortly expected to have a maximum spindown rate.展开更多
The objective of this study is to design an elastic neutron scattering system<span><span style="font-family:;" "=""> according to the angle with a sample using thermal neutron beam...The objective of this study is to design an elastic neutron scattering system<span><span style="font-family:;" "=""> according to the angle with a sample using thermal neutron beam at the Dalat <span>Nuclear Reactor (DNR). The system is used for research and training in the</span> field <span>of material structure analysis by neutron scattering and diffraction tech</span>nique</span></span><span><span style="font-family:;" "="">s</span></span><span><span style="font-family:;" "="">. It is designed on the basis of inheriting the neutron measurement spectrometer systems at the DNR and the scattered neutron measurement systems in the world. The measuring system, which was installed at the hori<span>zontal channel</span></span></span><span><span style="font-family:;" "=""> </span></span><span><span style="font-family:;" "="">4 of the DNR, consists of </span></span><span><span style="font-family:;" "="">5-helium-3 detectors and a fully</span></span><span><span style="font-family:;" "=""> electronic system to record the scatter counts <span>and a mechanical system with the possibility of rotating at 15</span></span></span><span><span style="font-family:;" "=""><span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span></span></span><span><span style="font-family:;" "="">-</span></span><span><span style="font-family:;" "="">75</span></span><span><span style="font-family:;" "=""><span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span></span></span><span><span style="font-family:;" "=""> </span></span><span><span style="font-family:;" "="">angles. The constructed system is tested for <span>evaluation of the accuracy, stability and reliability of the mechanical and</span> electronic systems of moving detector</span></span><span><span style="font-family:;" "="">s</span></span><span><span style="font-family:;" "=""> by angles.</span></span>展开更多
基金supported by the Xinjiang Bairen projectthe National Natural Science Foundation of China (NSFC, 11103021)+2 种基金West Light Foundation of CAS (LHXZ201201)Youth Innovation Promotion Association of CASthe National Basic Research Program of China (973 Program, 2015CB857100)
文摘SGR J1745-2900 is a magnetar near the Galactic center. X-ray observations of this source found a decreasing X-ray luminosity accompanied by an enhanced spindown rate. This negative correlation between X-ray luminosity and spindown rate is hard to understand. The wind braking model of magnetars is employed to explain this puzzling spindown behavior. During the release of magnetic energy of magnetars, a system of particles may be generated. Some of these particles remain trapped in the magnetosphere and may contribute to the X-ray luminosity. The rest of the particles can flow out and take away the rotational energy of the central neutron star. A smaller polar cap angle will cause the decrease of X-ray luminosity and enhanced spindown rate of SGR J1745-2900. This magnetar is shortly expected to have a maximum spindown rate.
文摘The objective of this study is to design an elastic neutron scattering system<span><span style="font-family:;" "=""> according to the angle with a sample using thermal neutron beam at the Dalat <span>Nuclear Reactor (DNR). The system is used for research and training in the</span> field <span>of material structure analysis by neutron scattering and diffraction tech</span>nique</span></span><span><span style="font-family:;" "="">s</span></span><span><span style="font-family:;" "="">. It is designed on the basis of inheriting the neutron measurement spectrometer systems at the DNR and the scattered neutron measurement systems in the world. The measuring system, which was installed at the hori<span>zontal channel</span></span></span><span><span style="font-family:;" "=""> </span></span><span><span style="font-family:;" "="">4 of the DNR, consists of </span></span><span><span style="font-family:;" "="">5-helium-3 detectors and a fully</span></span><span><span style="font-family:;" "=""> electronic system to record the scatter counts <span>and a mechanical system with the possibility of rotating at 15</span></span></span><span><span style="font-family:;" "=""><span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span></span></span><span><span style="font-family:;" "="">-</span></span><span><span style="font-family:;" "="">75</span></span><span><span style="font-family:;" "=""><span style="white-space:nowrap;"><span style="white-space:nowrap;">˚</span></span></span></span><span><span style="font-family:;" "=""> </span></span><span><span style="font-family:;" "="">angles. The constructed system is tested for <span>evaluation of the accuracy, stability and reliability of the mechanical and</span> electronic systems of moving detector</span></span><span><span style="font-family:;" "="">s</span></span><span><span style="font-family:;" "=""> by angles.</span></span>
