Thermoluminescence centres created selectively in MgO crystals by fast neutrons.

A possibility of using the thermoluminescent detection of collision-created interstitial centres in MgO by the TL peak at 700 K, arising at the radiative recombination of anion interstitials with F+ centres, for the selective detection of fast neutrons in mixed neutron-gamma fields, is examined. Selectivity and sensitivity of such a detector are discussed. For the present time, the sensitivity of the thermoluminescent detection of anion interstitials created by neutron irradiation is comparable to that of the EPR detection of F+ centres, the main limitations of the thermoluminescence method being connected with the background thermoluminescence and absence of suitable luminescence centres in this temperature region, when undoped and untreated MgO crystals are used. Possible ways to overcome these shortcomings are discussed.

Continuous-wave room-temperature laser oscillation of Cr(3+):MgO.

Continuous-wave laser oscillation of Cr(3+):MgO at room temperature was realized under argon-ion laser pumping at 476 and 514 nm. The free-running laser wavelength was 840 nm, and with different mirror sets laser oscillation at 824, 830, 870, and 878 nm was also realized. With different crystals a maximum output power of 48 mW and a lowest threshold with respect to the absorbed pump power of 80 mW were realized. The slope efficiencies with respect to the absorbed pump power were as high as 2.3%. No thermal effects were observed for absorbed pump powers as great as 2.7 W.