A Monte Carlo Generator for Full Simulation of e+e- to hadrons Cross section Scan Experiment

A generator with $\alpha^2$ order radiative correction effects, including both the initial state radiative corrections and the photon vacuum polarization corrections, is built for the full simulation of $e^+e^- \to hadrons $ in cross section scan experiment in the quarkonium energy region. The contributions from the hadron production structures including the resonances of $1^{--}$ quarkonium families and the light hadrons spectrum below 2 GeV as well as the QED continuum hadron spectrum are all taken into account in the event generation. It was employed successfully to determine the detection efficiency for selection of the events of $e^+e^-\to hadrons$ from the data taken in the energy region from 3.650 GeV to 3.872 GeV covering both the $\psi(3686)$ and $\psi(3770)$ resonances in BES experiment. The generator reproduces the properties of hadronic event production and inclusive decays well.