Tungsten Target of Obtaining Neutron Beams for CSNS

Through solid tungsten target to obtain neutron beams, the Chinese spallation neutron source (CSNS) project completed with high quality in exploring the microscopic world, filling the gap in the domestic pulse neutron application field.

In a lush lychee forest in Dalang town, Dongguan city, Guangdong province, there is a large scientific device built in China - the CSNS. After more than 10 years of preparation, 6 years of construction and over half a year of open operation, this "super-microscope", known as the "national heavy weapon", ushered in a harvest season.

CSNS was jointly built by the Chinese Academy of Sciences and Guangdong Province, making China be the fourth country in the world with a pulsed spallation neutron source. It has broad application prospects in many fields and will be of great significance for China to explore cutting-edge scientific issues, overcome industrial key core technologies, and solve "card neck" problems.

Previously, the pulsed neutron sources that were operating in the world were only ISIS in the UK, SNS in the US, and J-PARC in Japan. Chinese scientists realized that only by building a sparse neutron source can we have our own "eyes of fire" to explore the micro world.

The proposal to build a sparse neutron source in China originated from the study of China's high-energy physics development strategy in the late 1990s. The senior scientists of the Institute of High Energy Physics of the Chinese Academy of Sciences and the China Institute of Atomic Energy pointed out the necessity of building sparse neutron sources for the development of national science and technology. In September 1999, the two institutes submitted a proposal for the construction of spallation neutron sources to the Ministry of Science and Technology of the People’s Republic of China. In August 2000, the two units officially proposed the national major scientific project - "Multi-Purpose Neutron Scientific Devices Pulse Strong Neutron Source".

How does the spallation neutron source become a "super microscope" for exploring the microcosm? This starts with tiny and magical neutrons.

Deep into the 17 meters underground CSNS accelerator tunnel is the "big behemoth" - it includes a linear accelerator of 80 million electron volts, a fast cycle synchrotron with 1.6 billion electron volts, and a target station. And three neutron scattering spectrometers for scientific experiments.

The spallation neutron source device is a whole composed of various high, fine and sharp equipment. The device works by accelerating protons to 1.6 billion electron volts and speeds up to 0.93 times of light speed. The proton beam is used as a "bullet" to bombard a heavy tungsten target with a high atomic coefficient. The tungsten nucleus is hit with a mass of neutrons. Neutrons through special devices used to carry out varies experiments by scientists.

In fact, the construction process of CSNS can be described as a difficult task. From the mastery of key core technologies to equipment installation and project management, there are many challenges.

At 10 o'clock on the morning of August 28, 2017, the CSNS target station spectrometer controlled the room, and the researchers stared at the screen and stood by. After a command, the proton beam ejected from the accelerator hit the metal tungsten target, and the neutron beams were successfully obtained for the first time. The engineers present at the scene witnessed this historic moment with excitement - the first neutron generation of Chinese spallation neutron source, entered the trial run!

In the autumn of 2018, all the construction tasks of China's spallation neutron source were completed with high quality, which filled the gap in the domestic pulse neutron application field and built the international advanced level of spallation neutron source device.

The neutron beams obtained from the tungsten target led CSNS achieve a series of major technical achievements in the accelerator, target station and spectrometer, which has significantly improved the high-power spallation in China. The technical level and independent innovation capability in the fields of targets, magnets, power supplies, detectors and electronics have enabled our country to achieve a leap in high-current proton accelerators and neutron scattering.

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