In late August, the China Spallation Neutron Source (CSNS) produced its first neutron beam, representing an important milestone for the $280 million project. The world’s fourth pulsed spallation neutron source, following ISIS in the UK, SNS in the US and J-PARC in Japan, CSNS is located in the city of Dongguan in Guangdong province and is expected to become an important base for research and innovation in China and the surrounding region. CSNS entered construction in 2011 and is being built and operated by the Institute of High Energy Physics in collaboration with the Institute of Physics, both part of the Chinese Academy of Sciences.

A spallation neutron source uses intense pulses of protons to strike a target, producing a beam of neutrons that have been knocked out of the target nuclei. CSNS is driven by a 80 MeV H linac and a 1.6 GeV rapid cycling synchrotron, providing a 100 kW proton beam. The protons strike a solid tungsten target and the emerging neutrons are slowed using three moderators, before being delivered to the instrumentation facilities. A second phase of the project, upgrading the linac to 250 MeV and the proton beam power to 500 kW, is planned for the near future.

At 10.56 a.m. on 28 August, a proton beam pulse from the accelerator collided with the tungsten target for the first time. Neutron detectors located at two of the facility’s 20 beamlines measured the neutron spectrum, showing that the neutron beam had been successfully produced. The spectrum was consistent with the prediction from Monte Carlo simulations, with a higher neutron yield than expected.

Construction of the first three neutron spectrometers is also complete. A general-purpose powder diffractometer will be used to study crystal and magnetic structures of materials, while a small-angle neutron-scattering instrument will probe structures such as polymers at the level of 1–100 nm. A third instrument, a multipurpose reflectometer, will analyse neutrons reflected from a sample to study the surface and interface structure of materials.

These and other instruments will soon be available to users from around the world for research in materials science and technology, life sciences, physics, the chemical industry, environment, energy and other fields. Commissioning of the spectrometers is under way, on track for the facility to open to users in the spring of 2018.