Abstract: Background: The spallation neutron source can generate pulsed white neutron beam and has the advantages such as very high neutron flux and low thermal power, which is used widely in many fields. One of its applications is for nuclear data measurement. However, up to now, no nuclear data measurement based on the white neutron has been carried out in China due to the lack of the white neutron source. Purpose: The China Spallation Neutron Source (CSNS), which is now under construction, will provide us a good opportunity to do nuclear data measurement with its back-streaming neutron beamline. This beamline can provide very intensive neutron flux and reasonable time resolution of white neutrons which are very suitable for nuclear data measurement. Methods: This paper introduces part of the physical design of the back-streaming neutron beamline, especially the Monte Carlo simulation of the two end-stations’ background and the collimator system. Results and Conclusion: According to the simulation results, the neutron and gamma background in the end-stations are very low. And the beam profile of the CSNS back-streaming white neutron source can be well controlled. With the low intensity of background and well designed beam profile, we can develop very high precision nuclear data measurement with the CSNS back-streaming white neutron source.

Key words: China Spallation Neutron Source (CSNS), White neutron source, Nuclear data measurement, Monte Carlo simulation