2012
article
OpenAlex
F. De Mori, М. Н. Ачасов, D. Ambrose, F. F. An et autres
The decays $J/{\\psi}{\\rightarrow}p\\bar{p}$ and $J/{\\psi}{\\rightarrow}n\\bar{n}$ have been investigated with a sample of $225.2×10^6$ $J/{\\psi}$ events collected with the BESIII detector at the BEPCII $e^+e^-$ collider. The branching fractions are determined to be $\\mathscr{B}(J/{\\psi}{\\rightarrow}p\\bar{p})=(2.112±0. 004±0.031)×10^{-3}$ and $\\mathscr{B}(J/{\\psi}{\\rightarrow}n\\bar{n})=(2.07±0.01±0.17)×10^{-3}$. Distributions of the angle $\\theta$ between …
2003
article
OpenAlex
S. S. Fang, Y. K. Heng, 黄光顺, 金山 et autres
Based on 4-prong events sample of J/psi decay and the psi' data sample, a method is developed to determine J/psi total number of two data sets which were taken from November 1999 to May 2001 at BES Pi. The results are (27.00 …
2001
article
OpenAlex
黄光顺, 李忠朝, 苑长征, 祁向荣 et autres
A method is introduced to measure the trigger efficiency in R scan experiment carried out with BESII at BEPC. The design of trigger table, offline event selection and calculation of efficiency are described. The principle of trigger efficiency measurement is: a data …
1999
article
OpenAlex
周莉, 阙有昆, 崔象宗, Jian Fang et autres
An upgrade has been performed on the barrel shower counter at Beijing spectrometer to improve the performance of this detector. For Bhabha events, the energy resolution is better than 21% / root E (E in GeV) and the spatial resolution along z …