The detection of very high energy γ-ray emission from the Galactic center has been reported by four independent groups. One of these γ-ray sources, the 10 TeV -γ-ray radiation reported by HESS, has been suggested a...The detection of very high energy γ-ray emission from the Galactic center has been reported by four independent groups. One of these γ-ray sources, the 10 TeV -γ-ray radiation reported by HESS, has been suggested as having a hadronic origin when relativistic protons are injected into and interact with the dense ambient gas. Assuming that such relativistic protons required by the hadronic model come from the tidal disruption of a star by the massive black hole of Sgr A＊, we explore the spectrum of the relativis- tic protons. In the calculations, we investigate cases where different types of stars are tidally disrupted by the black hole of Sgr A＊, and we consider that different diffusion mechanisms are used for the propagation of protons. The initial energy distribution of the injected spectrum of protons is assumed to follow a power-law with an exponential cut-off, and we derive the different indices of the injected spectra for the tidal disruption of different types of stars. For the best fit to the spectrum of photons detected by HESS, the spectral index of the injected relativistic protons is about 2.05 when a red giant is tidally disrupted by the black hole of Sgr A＊ and the diffusion mechanism is the Effective Confinement of Protons.展开更多
By means of programs GTMPAC based- on generalized triangle method,analysis and synthesis of mechanism design in accordance with absolutely graphicalmethod( absolutely germetrical method) are developed.In this paper,we...By means of programs GTMPAC based- on generalized triangle method,analysis and synthesis of mechanism design in accordance with absolutely graphicalmethod( absolutely germetrical method) are developed.In this paper,we make aspecial study about centering- point curve and circling- point curve and couplercurves based on Ball’s points.展开更多
Tunable color center lasers making use of electron trapping defects such as F A and F + 2 like centers in alkali halide crystals can deliver broadly tunable power over the near infrared 0.8—4.0μm range.The tunable r...Tunable color center lasers making use of electron trapping defects such as F A and F + 2 like centers in alkali halide crystals can deliver broadly tunable power over the near infrared 0.8—4.0μm range.The tunable range and their impressive feature of narrow linewidth make these solid state lasers important to molecular spectroscopy,pollution detection,fiber optics communication and other scientific research fields.The( F + 2) H center consisting of an F + 2 center and an neibouring O 2- ion,is one of the most important color centers.In this paper,we will study the preparation,absorption and emission spectra of the ( F + 2) H center in mixed crystal KCl KBr∶OH -. Single crystals of KCl,KBr and different compositions of KCl x Br 1-x solid solutions are growtn with 0.1mol%—0.3mol% KOH in the melt by the Czochralski technique in air.展开更多
基金funded by the National Natural Science Foundation of China (Grant Nos. 10873015, 10778716, 10573021, 10778064, 10673001 and 10433010)the National Basic Research Program of China (Grant 2009CB824800)
文摘The detection of very high energy γ-ray emission from the Galactic center has been reported by four independent groups. One of these γ-ray sources, the 10 TeV -γ-ray radiation reported by HESS, has been suggested as having a hadronic origin when relativistic protons are injected into and interact with the dense ambient gas. Assuming that such relativistic protons required by the hadronic model come from the tidal disruption of a star by the massive black hole of Sgr A＊, we explore the spectrum of the relativis- tic protons. In the calculations, we investigate cases where different types of stars are tidally disrupted by the black hole of Sgr A＊, and we consider that different diffusion mechanisms are used for the propagation of protons. The initial energy distribution of the injected spectrum of protons is assumed to follow a power-law with an exponential cut-off, and we derive the different indices of the injected spectra for the tidal disruption of different types of stars. For the best fit to the spectrum of photons detected by HESS, the spectral index of the injected relativistic protons is about 2.05 when a red giant is tidally disrupted by the black hole of Sgr A＊ and the diffusion mechanism is the Effective Confinement of Protons.
文摘By means of programs GTMPAC based- on generalized triangle method,analysis and synthesis of mechanism design in accordance with absolutely graphicalmethod( absolutely germetrical method) are developed.In this paper,we make aspecial study about centering- point curve and circling- point curve and couplercurves based on Ball’s points.
文摘Tunable color center lasers making use of electron trapping defects such as F A and F + 2 like centers in alkali halide crystals can deliver broadly tunable power over the near infrared 0.8—4.0μm range.The tunable range and their impressive feature of narrow linewidth make these solid state lasers important to molecular spectroscopy,pollution detection,fiber optics communication and other scientific research fields.The( F + 2) H center consisting of an F + 2 center and an neibouring O 2- ion,is one of the most important color centers.In this paper,we will study the preparation,absorption and emission spectra of the ( F + 2) H center in mixed crystal KCl KBr∶OH -. Single crystals of KCl,KBr and different compositions of KCl x Br 1-x solid solutions are growtn with 0.1mol%—0.3mol% KOH in the melt by the Czochralski technique in air.
