| abstract |
A glass tube, laser sealed at its ends, has an elongated cross section, two wide side faces, and two narrow side faces. The tube contains a radioactive gas and a transducer, such as a phosphor compound, responsive to the gas. The narrow side faces of the tube are thicker than the wide side faces. Preferably, the wide side faces are outwardly bowed and the narrow side faces are semicylindrical to form an oval cross section. The ratio of the total glass thickness of the wide side faces to the spacing between the wide side faces is approximately 0.7. |