High Energy Physics Institute and China Academy of Space Technology (CAST)

Author: Yuefeng Zhu

Today’s trip started with a pleasant weather. Blue skies and golden sunshine reminded people of southern California. After the breakfast in the early morning, we took a short ride on Tsinghua’s bus to the Institute of High Energy Physics (IHEP). Prof. Wang, a famous scholar in astrophysics and a friend of Prof He, acted as the host of today’s trip.

We first had an informal meeting and discussion with some of the Ph.D. students from the institute. We had an introduction of each person and what they were doing. It was pretty interesting to learn how diverse their research topics are. One of them was working on neutron stars using X-ray telescope. He claimed that he could observe the change of x-ray spectra from many binary neutron star systems and reveal the secrets of the universe. Another person was working Yabajin telescope in Tibet. This telescope was designed to be placed on a high altitude so that cosmic ray showers can be detected with minimum attenuation. There were also people working on medical instruments such as PET and CT. They said there were instruments built in-house and they use them to do software development.

After the short one-hour discussion, we were led to visit some labs. The first one was the manufacturing site of PET systems, including small animal PET and human PET. They use LYSO scintillator as the detector to 511-keV gammas. They have successfully modulized the detector so that they can be used for either small animal PET or full-size human PET. We saw the real machines of both versions. The next stop was the BEPCII, Beijing Electron Position Collider. This was the first major scientific project built in modern China, proposed by Nobel Prize laureate Tsung-Dao Lee. We learned in concept how the collider worked and how the positrons were generated (through pair production). The collider also has synchrotron beam outputs, which people can rent to study their materials or perform other analyses. Since the beam was turned on, we could not visit the tunnel. We saw the control center and were impressed by how intense the beam was. The last stop was the clean room IHEP used to make the detectors for space telescopes. There are several projects actively developing in the institute. The most interesting one was HXMT (Hard X-ray Modulation Telescope). Prof. He’s master degree involved working with the NaI scintillator detector of this telescope. After 30 years of additional efforts, this telescope finally became true and launched to space. The visit in IHEP ended with a special lunch in the dining room of the IHEP. Prof. He used to eat there and it is still serving people. Jim requested to taste Chinese version yogurt and he was impressed.

Still accompanied by Prof. Wang, we took the bus to travel to China Academy of Space Technology (CAST). It is the equivalent institute of NASA in the United States. We received a warm welcome from a professor of the institute, Rui You. On our way to the exhibition hall of the institute, we met the statue of Xuesen Qian (also known as Tsien Hsue-shen, who graduated from MIT and Cal Tech and was the father of Chinese space science). After sitting down in a nice meeting room, we were first shown a short movie to introduce CAST and its previous and current projects, including the first lunar exploration, space station and the Mars project. The lunar project, Beidou navigation system, and the Mars project drew a lot of attention from us. Several questions were raised to better understand the purpose and motivation of the projects. For example, people were pretty interested in the scientific goal of Chinese lunar project and how it differed from USA’s previous lunar exploration. The answer was China wanted to achieve better results with better instruments compared with USA’s project dating back to the 70’s. They are also interested in building the foundation for future deep-space exploration, such as the Mars project. After the intense discussion, we were led to the exhibition hall to see the full-scale models of the satellites. We were impressed by the size of the satellites and the number that CAST had actually built. There was also a real returned capsule from a manned space project. We could see the burned surface of the capsule and were deeply impressed by the achievement. There were also models for the lunar lander and rover. We were told that several radiation detectors mounted on the rover were designed and developed by Prof. Wang. The exhibition was the technical high light of the day.

Leaving CAST, the bus driver delivered us to the restaurant, which was arranged by Prof. He for a special reason, which was kept secret before the dinner. Since we arrived at the restaurant one hour earlier than the schedule, Prof. He took us to a nearby park called Purple Bamboo Park. With Prof. He’s introduction, we got to know that this was the first English corner, where Chinese people started to learn English after China’s reform and open policies. Now, there is no studying of English any more. Instead, many local people use the place to enjoy their lives with music and dancing. Later, we received the special introduction from Prof. He that one of his high school classmates bought an apartment close to this park, and he built an incredible corridor inside his apartment using his skills as an architect. This short detour ended, and in the restaurant, we met this legendary architect. We also revealed the secret of the dinner place: it was a place where people can eat and watch performance in the same time.

The food was incredible. People liked the soy source pork and squirrel fish a lot. The performance started in the middle of the dinner. The first performance was a Sichuan Opera face changing, which was a unique cultural legacy from southern China. We also heard Beijing Opera and Chinese fellow music. They are both unique to American students. Another impressive entertaining performance was happy kitchen. The actor showed off his skill to rotate 10 plates simultaneously. He also used comedy elements in his show and created lots of interaction between the actor and the audience. Both David and Emily enjoyed the special service.

The dinner was a special treat from Prof. He and his high school classmates. All of us appreciated their generosity. We also appreciated the help of the young lady from the education section of IHEP to arrange the tour there. There were also two Tsinghua students accompanied us during the day, and we would like to thank them.