The Bartol-University of Delaware Proton Microprobe

The Bartol Research Foundation and the Physics Department of the University of Delaware have jointly set up a proton microprobe for the observation of proton induced x rays and ¿ rays. The protons with energies up to 2.5 MeV are accelerated in a Van de Graaff and pass out into the atmosphere through holes as small as 10 ¿m. The x rays, for elements above sodium, are detected in a 6 mm diameter by 3 mm deep Si(Li) diode; whereas the gamma rays, for the lighter elements, are detected in a 55 cc Ge(Li) diode. Examples are given of preliminary studies of amorphous alloys, trace elements in microtektites metamorphosed marbles, skarns and pegmatites, chemical composition of the shell of oysters cultured in controlled systems and archaeological artifacts.