分类: 物理学 >> 核物理学 提交时间: 2022-01-21 合作期刊: 《Nuclear Science and Techniques》
摘要: By implementing an additional heavy quarkantiquark pair production trigger in a multiphase transport (AMPT) model, we study the effect on anisotropy flows of identified particles with a focus on charged particles and quarkonium (J/ and ). A systematic increase in the collision rate for active partons in the AMPT model with such an implementation has been observed. It leads to a slight increase of identified particles anisotropy flows as a function of transverse momentum (pT ) and rapidity, and gives a better description of the experimental data of elliptic flow toward larger pT . Our approach provides an efficient way to study the heavy quark dynamics in the AMPT model at LHC energies.
分类: 生物学 >> 动物学 提交时间: 2023-09-20 合作期刊: 《古脊椎动物学报》
摘要: 间型三棱齿象(Trilophodon connexus Hopwood, 1935)长期以来被认为是中国嵌齿象属 (Gomphotherium)的一个代表种。然而,由于其下颌联合部与下门齿的形态未知,这一归入 存疑。重新研究了来自新疆准噶尔盆地北缘乌伦古河地区哈拉玛盖组的一件此前归为陕西嵌齿象相似种(Gomphotherium cf. G. shensiensis)的下颌。该下颌联合部伸长,呈深槽状, 下门齿缺失,因此确定可归入豕棱齿象科(Choerolophodontidae)。进一步将间型三棱齿象 的正型标本与其相比较,两者颊齿的关键特征完全一致,包括:高度丘型化,m3伸长, 具有四脊,上下颊齿第二脊人字型(chevron)很弱,第二脊中附锥与前中心小尖不愈合, 釉质褶皱、齿谷中小锥及白垩质发育弱或缺失。因此,间型三棱齿象事实上是一种豕棱齿 象类而非嵌齿象。综上所述,暂将其改定为间型豕棱齿象 (Choerolophodon connexus (Hopwood, 1935))。同时,以上特征与北美的索普颌门齿象(Gnathabelodon thorpei)比较接 近。此外,在颌门齿象属和间型豕棱齿象中,颊齿第二脊呈人字型, 釉质褶皱、齿谷中 小锥及白垩质发育强这些典型的豕棱齿象属(Choerolophodon)的特征较弱甚至缺失,但m3 齿脊数变多,这表明颌门齿象属可能起源于东亚的间型豕棱齿象。
分类: 核科学技术 >> 核探测技术与核电子学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: Resistive Plate Chambers (RPCs) built from a new type of Bakelite developed at Institute of High Energy Physics (IHEP), Chinese Academy of Sciences have been used in the BESIII Muon identification system for several years without linseed oil coating, but characteristic aging performances were observed. To adapt to the RPCs in the aging state, the front-end electronics have been upgraded by enhancing the front-end protection, improving the threshold setting circuit, and separating power supplies of the comparator and the field programmable gate array (FPGA). Improvements in system stability, front-end protection and threshold consistency have been achieved. In this paper, the system upgrade and the test results are described in detail.