DETECTION OF ULTRAVIOLET-RADIATION IN THE ACTINIC RANGE AT THE EARTHS SURFACE USING EU-DOPED NACL-CRYSTALS (VOL 20, PG 605, 1992) - ESPANA, E; CALDERON, T; CUSSO, F; JAQUE, F; LIFANTE, G; TOWNSEND, PD; (Nuclear Tracks And Radiation Measurements, 1993)