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The China Spallation Neutron Source is an accelerator-based neutron source, operated by the Institute of High Energy Physics, at Dongguan in Guangdong province - the first major scientific facility in south China. The project was approved by Chinese central government in 2005. Construction began 20 October 2011,[1] with commissioning planned for 2016, and operation in 2018.[2]
The source contains a proton synchrotron fed by a linear accelerator; short (<500ns) pulses of 1.63×1013 1.6 GeV protons are extracted from the synchrotron 25 times a second;[3] these pulses strike a tungsten-metal target (cooled with heavy water) to produce energetic neutrons, which are reduced to scientifically interesting energies by a variety of moderators.
The intended budget for the project is 1.5 billion CNY;[4] this limits the initial power of the machine to about 120 kW, but it has been designed so that its power can readily be quadrupled if more funding becomes available, by upgrading the linear accelerator and the RF components of the synchrotron.
In March 2018, the China Spallation Neutron Source project was completed [5]. In August 2018, the project passed the national acceptance.[5] At the end of September 2018, the China Spallation Neutron Source was opened to domestic and foreign users.[5]

On December 26, 2022, the National Development and Reform Commission approved the feasibility study report for the Phase-II of the China Spallation Neutron Source (CSNS) project.[6] The Phase-II of the project will build 11 neutron spectrometer terminals and increase the beam power of the accelerator and target station to 500 kW, with an estimated investment of RMB 3 billion.[7] The upgrade will allow the CSNS to test smaller samples, improve experimental accuracy, and speed up data collection time.[8] On March 30, 2024, the Phase-II of the CSNS project was launched and is expected to be completed in August 2026.[9]
In February 2020, the target beam power of the spallation neutron source reached the originally designed 100kW; in February 2022, the target beam power was increased to 125kW; in September 2022, the target beam power was further increased to 140kW; and in March 2024, the target beam power was further increased to 160kW.[10]
On October 21, 2024, the beam power of the spallation neutron source was increased to 170kW, which not only improved the efficiency of the device, but also verified the technical route used for the second phase beam power increase of the spallation neutron source. [11] On March 4, 2026, the beam power was increased to 185kW.[12]
Source:[13]
The most visible application of CSNS technology is in Boron Neutron Capture Therapy (BNCT).
Neutrons are uniquely capable of "seeing" light elements like Lithium and Hydrogen inside dense metal containers, making CSNS the premier lab for the energy transition.
Residual Stress Mapping: CSNS is the only facility in the region capable of measuring internal "residual stress" deep within massive components without destroying them.