P.R. BELL: SCANNING THE FUTURE
Physicist P. R. Bell came to the Laboratory from the University of Chicago in 1946. During the war, he had worked at the U.S. government's radiation laboratory at the Massachusetts Institute of Technology, which sought to improve the effectiveness of radar in detecting aircraft and ships.
At the Laboratory, he led a scientific team that focused on developing new instruments. The team sought to improve the scintillation spectrometer, an electronic device for detecting and recording small pulses of light, or scintillations, emitted by phosphors when bombarded by radiation.
In the early 20th century, the United Kingdom's renowned scientist Lord Rutherford visually counted scintillations in alpha particle experiments. Visual methods were later replaced by the Geiger counter. After World War II, scintillations were detected by photomultiplier tubes, which were highly sensitive to light. In this technique, phosphors were placed in the direct path of radiation and the emitted light was converted into electric signals. The signals were then amplified and registered as electrical pulses with a circuit similar to that used in Geiger counters.
Recognizing the potential value of this device for detecting and measuring beta and gamma rays, Bell and his colleagues improved the scintillation spectrometer, achieving notable success in developing instruments that measured radiation levels and energies.
These improvements had practical applications not only for radiation dosimetry but also for medical diagnosis. Bell and his colleagues C. C. Harris and J. E. Francis, for example, modified this radiation detector for use in locating brain tumors. The detector highlighted trouble spots, making intrusive surgery unnecessary for cancer detection.
Today, scanners based on Bell's improved device are an essential tool of medical diagnosis used by doctors throughout the world to locate cancerous tumors and examine the results of other internal diseases. Bell's pioneering studies on the scintillation spectrometer, and the improvements and adaptations that followed, have prevented untold human suffering and extended millions of lives.
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