Radiological and Environmental Research Division Annual Report. Radiation Physics. July 1973 - June 1974
- Argonne National Lab. (ANL), Argonne, IL (United States)
In the past year, the Radiation Physics Section has enhanced its strength considerably. With improved technical capabilities in all three areas - electron scattering by molecules, photoabsorption and photoionization processes, and pertinent theoretical studies -we now approach closer than ever before our eventual goal: the elucidation of elementary mechanisms of radiation actions. A highlight of the electron-scattering program is the initial operation of the electron energy-loss spectrometer (as described in paper 13 of this report) . After some effort directed toward its technical perfection, this apparatus will generate important data for years to come. Another apparatus that uses a trapped-electron technique has exhibited unprecedented versatility in the study of electron-molecule collisions; different modes of operation of this single instrument enable one to study resonances in low-energy electron-molecule interactions (papers 30 -3 2, 35, and 3 6), to measure the excitation functions of individual excited states (paper 33), and even to clarify the intricacies of ionizing collisions of electrons near the ionization threshold (paper 34) . Studies on photon interactions with molecules have likewise been successful. The absolute measurement of photoabsorption and photoionization cross sections in the far vacuum-ultraviolet region is now well under way (papers 17 and 18) . We consider it a unique advantage to conduct both electron energy-loss analyses and photoabsorption measurements in the same group; cross-checking of the oscillator strength from the two independent sources often helps us assess the data reliability and sometimes offers a new insight into the physics involved (papers 14-18). The photoelectron analysis has produced significant results on partial photoionization cross sections (papers 21 and 22) . Theoretical studies have been extended in several ways. First, there were serious attempts to improve theories that connect various radiation chemical yields to basic cross-section data (papers 1-3). Second, analyses of the secondary-electron data (papers 4-6) now make possible a realistic assessment of this crucial element in the theoretical prediction of primary yields. Third, the application of a multiple-scattering method to molecular electronic continua has demonstrated its power in systematic calculations of cross sections for photoionization and electron scattering of molecules (papers 28 and 29). Finally, we have extended the scope of our research to include the spectroscopy of highly stripped ions (paper 41), a subject of increasing importance because of the advent of heavy-ion accelerators and also because of its relevance to controlled ,thermonuclear research. We are proud of having played major roles in two important meetings. Together with the Health Physics Division of the Oak Ridge National Laboratory, we organized the Symposium on the Jesse Effect and Related Phenomena, Gatlinburq, Tennessee, November 1973. The Symposium honored Dr. W. P . Jesse, a pioneer in radiation physics and an earlier head of the group from which this Section has evolved, and provided an opportunity for fruitful discussion among workers in diverse fields ranging from basic radiation physics to vacuum-ultraviolet laser technology. We were especially honored -to have Dr. Jesse at the Symposium, but were saddened by his death only about three months later. A full record of the Symposium was published in Radiation Research, August 1974. The Section also helped to organize a full-day symposium on the basic physics of the interactions with matter as a part of the 5th International Congress of Radiation Research, Seattle, Washington, July 1974. The symposium was dedicated to the memory of the late Professor R. L. Platzman, who was an early leader of our group, and whose tradition in radiation research will continue to influence our activities for years to come.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- US Atomic Energy Commission (AEC)
- DOE Contract Number:
- W-31-109-Eng-38
- OSTI ID:
- 1165979
- Report Number(s):
- ANL-75-3-PT1
- Country of Publication:
- United States
- Language:
- English
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