From earth to space: ESR dosimetry moves towards the 21st century

Future developments of electron spin resonance (ESR) dosimetry, dating and imaging (microscopy) are discussed following a brief review of the present state of the art. The Third International Symposium on ESR Dosimetry and Applications in 1991 gives an opportunity for an outline of further developments of the methods as we move towards the 21st century. One direction these developments need to take is toward space sciences where ESR dosimetry of solar wind, particulate radiation as well as dating of planetary and interplanetary substances like comets and asteroids must be studied first in the laboratory. Physics on defects in solid H2O, CO2 and CH4 abundant in outer space must be studied. Improvement of the alanine dosimeters and monitoring irradiated foods and the in-vivo human tooth dosimeter for accident dosimetry are essential in the development of ESR dosimetry. ESR ages of geological substances must be refined on a firm physical basis by establishing models of defects whose signals are used for ESR dating. Finally, magnetic resonance imaging (MRI) both CT- and scanning ESR for spatial distribution of spins must be developed with the pulsed ESR method which can separate overlapping signals with different relaxation times. A small portable ESR will make this ESR metrology more practical in many fields. The sensitivity increase can be realized by cooling the oscillator and detector diode and electronics to reduce thermal noise. (author)