TABLE OF CONTENTS This phosphor is a near tissue equivalent material with an effective atomic number for photoelectron absorption equal to 8.4.
The preparation of polycrystalline magnesium borate activated by dysprosium has been reported at first in 1974 [1]. A certain quantity of magnesium carbonate MgCO 3, boric acid H 3BO 3, and dysprosium nitrate Dy(NO 3) 3. is placed in a quartz cup and dried at a temperature ranging between 80 and 100 C. After that the material is annealed in a furnace, then cooled, ground, and screened.
The most sensitive material is obtained at the proportion of boric anhydride and magnesium oxide 2.2 to 2.4 and at the dysprosium concentration of about 1 mg-atom per g-mol of the base.
The glow curve of such a material shows a single peak located in the region from 190 to 200 C.
The sensitivity is reported to be 10 to 20 times larger than that of LiF. The energy response at 40 keV is about 30% larger than that of LiF. The TL response Vs dose is linear from 10 ?5 to 10 Gy. Fading at room temperature is about 25% over a period of 40 days.
A development of the preparation method of magnesium borate activated by Dy and Tm and other unknown impurities added as co-activators, was presented in 1980 [2]. The sensitivity has been reported to be about seven times greater than that of LiF; other investigators reported a factor...
