After BEPCII finished data accumulation at the psi (3770) peak on May 3, 2011, the center of mass energies of the BEPCII was increased to 4.01 GeV to collect psi (4040) data. The peak luminosity reached above 0.55x10³³/cm²/s after two injections, and the BESIII detector was in excellent status.

The psi (4040) is a radial excitation of the J/psi and psi', and the data at this resonance can be used to study the charmonium spectroscopy, charmonium transition, and the decay properties of the strange charm meson, Ds.

The world largest data sample collected so far was the BESI experiment from 1992 to 1994, with an integarated luminosity of 22.3 pb^-1. CLEOc did an energy scan between

3.97 GeV and 4.06 GeV, and it took 20.6 pb^-1 data at six energy points.

In accodance to the running schedule for the following month, BESIII will accumulate at least 500 pb-1 at this energy with an aim to search for the excited charmonium states and the charmonium-like states (also known as the XYZ particles), and to measure the Ds decay constant and other physics quantities at high precision.

The peak luminosity of the BEPCII has been at around 0.5x10³³/cm²/s since its operation, and BESIII has accumulated more than 140 pb-1 data in about oneweek, which is now the world largest data sample at this energy point. Currently, the data sample continues to increase by about 20 pb-1 per day.