The so-called scintillation crystal is a kind of scintillation fluorescence that emits a certain wavelength in a crystal when high-energy particle beams are irradiated onto the crystal. After the photoelectric conversion system and the electronic device, the energy of the particles can finally be determined. The Shanghai Institute of Ceramics, Chinese Academy of Sciences, has developed BGO, CeF3, BaF2, CsI, and PbWO4 through knowledge innovation. PWO) and other scintillation crystals. The above-mentioned new types of scintillation crystals have undergone multiple international tests and have won many world firsts. For example, lanthanum gallate crystals have won the first place in quality and size in the world. Lead tungstate crystals have the world's highest luminescence and comprehensive performance. The world's highest quality and large size cesium fluoride crystals, and the world's largest output and uniformity of cesium fluoride crystals. First, antimony-doped yttrium iodide crystals have the world's first radiation resistance.

 

The above five new scintillation crystals have been widely used in fields such as high-energy physics, nuclear physics, astrophysics, radiation medicine, and geological petroleum exploration for their excellent scintillation performance. The Shanghai Silicate's scintillation crystals are widely used in high-energy physics, such as positive and negative electron colliders, hadron colliders, B-Factory and other large-scale electromagnetic energy sensors, and positron electron-scanning in nuclear medicine. instrument.

 

The research, development and production of the above novel scintillation crystals were conducted under the direct leadership and organization of Academician Yan Dongsheng, academician Yin Zhiwen and Academician Guo Jingkun of the Institute of Honorary Directors of the Institute, as well as the Deputy Directors Dai Yuanchao, Fang Xuanlang and the main leader He Chonghan at the time. Directors of Crystal Research, Researchers), Fan Shiqi (researcher), Liao Jingying (researcher), Shen Dingzhong (researcher), Hu Guanqin (researcher) and other teams led by relevant teams to tackle challenges, knowledge innovation, emancipate the mind, explore new ideas, promote team spirit, and make concerted efforts Research has been made. In November 1986, Hu Yaobang, the then general secretary of the CPC Central Committee, visited the institute's inscription "New Materials to Go to the World." Shanghai Institute of Ceramics did exactly that.

 

One or five new scintillation crystals

 

1. BGO scintillation crystals

 

BGO scintillation crystals, with a large effective atomic coefficient, high density. The short fluorescent afterglow, good physical and chemical stability, is one of the preferred materials for the construction of electromagnetic energy estimators in high-energy physical detectors. It has extensive applications in nuclear medicine, space physical and geological prospecting, and nuclear electronics.

In 1978, the institute cooperated with the development of China's key project X-ray tomography scanner (XCT) to undertake the BGO crystal development task. It was successfully developed in 1979 and was used in China's first XCT prototype.

 

In the early 1980s, the European Nuclear Research Center (CERN) prepared to build the world's largest positive and negative electron collider. In 1981, the LEP3 cooperation team headed by Professor Chong Tingzhong of CERN proposed to use BGO crystals to build electromagnetic energy balancers. Not only do they require a large crystal size (3x3x24cm), a large number (12,000 roots, weighing about 10 tons), they require not only good optical and scintillation performance, but also low prices. The 1983 Nobel Prize-winning physicist and Chinese-American scientist Ding Yizhong was guilty of using a large number of BGO scintillation crystals to build a large electronic collider at the time. When he was seen, he was the vice president of the Chinese Academy of Sciences and the director of the Shanghai Silicate Institute. After Yan Dongsheng’s academician, he desperately wanted the help of Yan’s academician. He hopes that the Chinese Academy of Sciences can provide a large-size, high-quality BGO crystal with a total number of more than 10,000. Yan Jianshi realized that it was important to participate in the scientific project that attracted worldwide attention and resolutely accepted the other party’s request.

 

At that time, although the lab's researchers successfully developed small-sized samples, it was difficult to produce crystal materials with large size and excellent performance according to international and domestic conditions at that time. Academician Yan after analysis, that if you change the crystal growth program, it is possible to achieve this goal. Under the leadership and organization of Yan’s academician, through the hard work of his organization team, the difficulties were overcome. Through a year of experimental research, crystal materials with a length of 30 cm and excellent performance and large dimensions were born in the Institute. At that time, the United States, Japan, and France related companies were also engaged in research and development. In March 1983, the comparative performance of CERN's performance, the silicate crystal BGO crystal topped the list and won two world first, namely the crystal quality. First, size first. In September of the same year, CERN conducted comparative tests on BGO crystals from the United States, Japan, France, and silicates. The evaluation results indicated that the three most important indicators of fluorescence efficiency, energy resolution, and light attenuation are the crystals of silicate crystals. the first. Dachang China's reputation in the field of crystal materials. On this basis, the firm signed a contract with the LEP3 group. After two years of hard work, we have completed the development work from the laboratory results to large-scale (3.5x70x250mm) mass production, ensuring the quality and yield of batch crystals, and becoming the largest BGO crystal production scale in the world with reliable quality and the most reputable units. . By 1988, the Institute had completed the task of 12,000 tons of BGO large crystals with a total weight of 12 tons required by the European Nuclear Research Center's electromagnetic energy analyzer six months ahead of schedule. It is rare that high-purity large single crystals are measured in tons. This achievement not only made silicate known internationally, but also played an effective incubator role for the Chinese Academy of Sciences in the research and development of high-tech materials and won credibility at home and abroad. As Professor Ding Xiaozhong said: "To BGO crystals, go to the Shanghai Institute of Ceramics, Chinese Academy of Sciences!" At the subsequent Plenum of the LEP3 Experimental Group, which was attended by hundreds of scientists from all over the world, held by CERN, Professor Yan Yanshi Shi Ding Yizhong The invitation was given a one-hour speech to give a comprehensive introduction to the achievements made by the Shanghai Silicate Crystal Institute and its contribution to the LEP3 project. The splendid and splendid speech won the applause of the audience and made the foreign scientific and technological community obtain from China. The achievements are impressive.