Driven by the frontier research of particle physics, humans have built various types of colliders. At the Xiangshan Science Conference held from August 30 to 31, scientists called for a new type of collider, the world's first gamma photon collider, to be built in China.
The gamma photon collider can use the conventional accelerator to generate reverse Compton scattering with high-energy high-frequency lasers, thereby causing high-brightness gamma beams to collide with each other.
“The concept of this collider was proposed more than 30 years ago, but there is currently no gamma photon collider built in the world.” Professor Zhou Renren from the National Fermi Laboratory explained that there are two reasons behind it. .
On the one hand, the development level of laser technology is not mature, and this technology has not been able to meet the requirements of the gamma photon collider until recently. On the other hand, after the concept of the gamma photon collider was proposed, scientists first thought of building a high-energy gamma photon collider, which was based on an energy range of 80-120 GeV (1 billion e-volts). High-energy electron accelerators, which are expected to take 20 years to achieve even under today's technical conditions.
Nowadays, the "Gamma Photon Collider Research Group" composed of Chinese particle physics scientists has jointly proposed a low-energy gamma photon collider construction scheme of MeV (million electron volts). They believe that this collider can be implemented on the basis of existing laser technology and particle accelerators.
“Since the 1980s, the laser power density has increased rapidly, from 1016 watts per square centimeter to 1022–1023 watts per square centimeter.” Huang Yongsheng, a researcher at the Institute of High Energy Physics, Chinese Academy of Sciences, introduced the low-energy gamma photon collider to green laser pointer technology. The requirements are relatively low and existing laser technology can meet its threshold.
The low-energy gamma photon collider also has a unique physical meaning compared to the high-energy gamma photon collider. For example, quantum field theory has been proposed 100 years ago, but it has not been directly verified by experiments. The MeV-scale gamma photon collider provides a unique platform for verifying quantum field theory. In addition, the gamma photon collider can be built for new experiments and new scientific discoveries.
Huang Yongsheng believes that the construction of low-energy gamma photon colliders can drive the development of relevant domestic technologies and talents, laying the foundation for the construction of higher-quality gamma photon colliders in the future.
Two years ago, the issue of whether to build a large particle collider in China had caused huge controversy in the scientific community. Compared to the former, the gamma photon collider is much smaller. According to the design plan of the Gamma Photon Collider Research Group, the world's first low-energy gamma photon collider will be built, covering an area of only 500 square meters. The construction cost is estimated to be 100 million to 200 million yuan. It can be completed in 3 to 5 years. .
"In the past, other types of particle colliders were first built by other countries. Now China has the conditions to build the world's first gamma photon collider. It should seize the favorable opportunity as soon as possible, otherwise it will be taken a step by other countries." Yongsheng said.
However, the experts pointed out that although the technical conditions for China's construction of the world's first gamma photon collider are basically mature, the challenges can not be ignored.
One of the difficulties is that the above design requires that the dual beam laser and the two beam electrons reach the two precise positions and collide at the same time, which requires a synchronization technique of the picosecond level. Although the best synchronization technology in China is higher than the picosecond level, it is only applied to single beam laser and single beam electron collision. The application of dual beam laser and double beam electron collision requires a lot of technical verification.