• Simulations of momentum correlation functions of light (anti)nuclei in relativistic heavy-ion collisions at p s NN = 39 GeV

    分类: 物理学 >> 核物理学 提交时间: 2023-06-20

    摘要: Momentum correlation functions of light (anti)nuclei formed by the coalescence mechanism of (anti)nucleons are calculated in several relativistic heavy-ion collision systems, namely B +B, O +O, Ca +Ca as well as Au +Au, at di#11;erent centralities at center of mass energy 39 GeV within the framework of A Multi-Phase Transport (AMPT) model complemented by the Lednick#19; y and Lyuboshitz analytical method. Momentum correlation functions for identical or nonidentical light (anti)nuclei are constructed in the above collision systems at so high collision energy. The results suggest that emission of light (anti)nuclei occurs from a source of smaller spacetime extent in more peripheral collisions. The e#11;ect of system-size on the momentum correlation functions of identical or nonidentical light (anti)nuclei is also explored in several central collisions. The results indicate that the emission source-size of light (anti)nuclei pairs deduced from their momentum correlation functions and system-size is self-consistent. Momentum correlation functions of nonidentical light nuclei pairs gated on velocity are applied to infer the average emission sequence of them. The results indicate that protons are emitted in average on a similar time scale with neutrons but earlier than deuterons or tritons in the small relative momentum region. In addition, larger interval of the average emission order among them is observed by large centrality and smaller system collisions.

  • SETI strategy with FAST fractality

    分类: 天文学 >> 天文学 提交时间: 2023-02-19

    摘要: We applied the Koch snowflake fractal antenna in planning calibration of the Five-hundred-meter Aperture Spherical radio Telescope (FAST), hypothesizing second-order fractal primary reflectors can optimize the orientated sensitivity of the telescope. Meanwhile, on the grounds of NASA Science Working Group Report in 1984, we reexamine the strategy of Search for Extraterrestrial Intelligence (SETI). A mathematical analysis of the radar equation will be performed in the first section, aiming to make it convenient to design a receiver system that can detect activities of an extraterrestrial civilization, according to the observable region of the narrowband. Taking advantage of the inherent potential of FAST, we simulate the theoretical detection of a Kardashev Type I civilization by a snowflake-selected reflecting area.