MEASUREMENT OF THE THERMOLUMINESCENT RESPONSE (SUPRALINEARITY AND EFFICIENCY) OF LIF-MG,TI EXPOSED TO 0.7 MEV PROTONS

The irradiation of LiF : Mg,Ti (TLD-100) chips by a defocused 0.7 MeV proton beam from an electrostatic accelerator has been achieved using radiochromic dye film to evaluate the beam transversal intensity distr ibution. The dose-response has been measured at fluences between 2.4 x 10(8) and 5.7 x 10(11) p/cm(2) and peaks 3-9 show linear-supralinear- sublinear response. The efficiency, relative to Co-60 gamma-rays, meas ured for the total thermoluminescent (TL) signal and peaks 5 and 7, eq uals 0.33, 0.22 and 1.4, respectively. The comparison of these and oth er low-energy data for peak 5 with Track Structure Theory (TST) effici ency calculations indicate that the latter must take into account the stopping of the incident ions in the dosimeter to achieve a reasonable agreement with the observations. In general, neither TST, nor Modifie d Track Structure Theory (MTST) are able to simultaneously predict the response to 5.3 MeV alpha-particles and 0.7 MeV protons for all the s tudied glow curve peaks. Track Interaction Model (TIM) and Unified Tra ck/Defect Interaction Model. (UNIM) calculations of the supralinearity function ( ) of peaks 5 to 8 for 5.3 MeV alpha-particles and peaks 5 to 9 for 0.7 MeV protons, qualitatively describe the general trends me asured in this work; only the UNIM agrees quantitatively with the data in both systems. (C) 1998 Elsevier Science B.V.