He Zehui

He Zehui the Chinese nuclear physicist (1914-2011) known as the Chinese Marie Curie, who made pioneering contributions to nuclear emulsion techniques, cosmic-ray research and the development of China's nuclear science, and who was for decades one of the most respected women of science in her country.

Early Life and Education

He Zehui was born on 5 March 1914 in Suzhou, Jiangsu province, into an intellectual family that valued learning highly. Her father, He Cheng, was a lawyer and educator who had studied in Japan, and he encouraged all of his children, daughters included, to pursue modern education at a time when that was still unusual. Several of her siblings became distinguished scientists, and the family produced a remarkable concentration of academic talent.

She attended the Zhenhua and other schools in Suzhou and showed an early aptitude for mathematics and the physical sciences. In 1932 she entered Tsinghua University in Beijing, where she studied physics and graduated near the top of her class in 1936. Her undergraduate years placed her among a small group of talented students who would go on to shape Chinese science in the following decades.

Hoping to work on the frontier of experimental physics, she travelled to Germany in 1936 and entered the Technical University of Berlin. She studied under distinguished physicists and completed a doctoral thesis on the scattering of fast neutrons, receiving her doctorate in engineering in 1940. The outbreak of war in Europe made a return to China impossible for several years, and she remained in Germany to continue research.

Research in Europe

During the Second World War He Zehui worked at the Kaiser Wilhelm Institute for Physics in Berlin, where she became expert in the use of nuclear emulsions and in precision measurement techniques. She built a cloud chamber and studied the scattering of neutrons by various nuclei, work that required delicate instrument-making and careful analysis. Her reputation for experimental skill grew steadily among her colleagues.

After the war she moved to France and worked at the College de France and the Curie Institute in Paris under the physicist Frederic Joliot-Curie and his collaborators. There she applied nuclear emulsion methods to the study of cosmic rays and nuclear fission. With her future husband Qian Sanqiang, whom she married in 1946, she carried out research on the splitting of uranium that earned the couple wide recognition.

Together they made the significant discovery that uranium nuclei can undergo fission into three fragments, not merely two, a phenomenon known as ternary fission. Using refined photographic emulsions they identified and measured these rare events with great precision. The result was regarded as an important contribution to nuclear physics and brought the young researcher international attention.

Return to China and Nuclear Science

In 1948 He Zehui and her husband returned to China, where they took up posts in Beijing and helped to rebuild scientific research after the disruption of the war years. She joined the Institute of Modern Physics, later part of the Chinese Academy of Sciences, and set about establishing laboratories and training a new generation of researchers in nuclear techniques.

She became a leading figure in the effort to develop China's capacity in nuclear physics. Her work on nuclear emulsions, detectors and measurement methods supplied essential tools for experiments, and she trained many students who went on to important careers. In recognition of her standing she was elected a member of the Chinese Academy of Sciences in 1980.

She also served for many years as a professor at the University of Science and Technology of China, where she guided graduate students and helped to build the curriculum in nuclear and particle physics. Her laboratory became a centre for detector development, and she was known for her insistence on meticulous experiment and for the care she took in the training of young scientists.

Cosmic Rays and High-Energy Physics

Much of her later research concerned cosmic rays and the elementary particles produced in high-energy collisions. She studied the composition and behaviour of the particles that arrive from space using emulsion stacks carried by balloons and later by satellites, a method well suited to recording rare and complex events that could not be reproduced in the laboratory of the time.

She was particularly interested in the heavy nuclei present in the primary cosmic radiation, whose relative abundances carry information about the sources and the propagation of cosmic rays through the galaxy. By analysing the tracks left in emulsions exposed at high altitude, she and her collaborators contributed to understanding how these particles are produced and accelerated in astrophysical settings.

Her studies also extended to the search for new particles and to the development of instruments for space-based observation. She advocated the use of Chinese satellites and high-altitude balloons for cosmic-ray research, and she helped to establish a tradition of experimental high-energy astrophysics in the country that continued long after her active career had ended.

Influence and Legacy

He Zehui was widely admired as a scientist, a teacher and a public figure. Her career spanned the transformation of Chinese physics from a modest pre-war base into a modern research enterprise, and she contributed at every stage as an experimenter, an organiser and a mentor. She was often called the Chinese Marie Curie in recognition of both her achievements and her determined independence.

With her husband Qian Sanqiang she formed one of the most celebrated scientific partnerships in modern China, and their home became a meeting place for leading researchers of the era. She worked to advance opportunities for women in science and served in a number of national advisory bodies, using her influence to support basic research and international cooperation.

She died on 20 June 2011 in Beijing at the age of ninety-seven, having remained engaged with science almost to the end of her life. Her papers, instruments and correspondence document a remarkable scientific career, and her example continues to inspire young researchers, especially women, in China and beyond. Commemorations and prizes have been named after her in later years.

See also

• Qian Sanqiang
• Nuclear emulsion
• Cosmic rays
• Chinese Academy of Sciences