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Significance of TL Radiation Dosimetry of Carbon Ion Beam in Radiotherapy
Published in Vikas Dubey, Sudipta Som, Vijay Kumar, Luminescent Materials in Display and Biomedical Applications, 2020
Karan Kumar Gupta, N.S. Dhoble, Vijay Singh, S.J. Dhoble
Carbon ion beam is a type of heavy charged particle beam and, as we know, when the heavy charged particle beam interacts with matter the ion beam loses its energy by a number of mechanisms, such as (i) Ionization and excitation, (ii) Nuclear collisions, (iii) Photon generation and (iv) Nuclear reactions. When TL materials are irradiated with HCP, total HCP stopping power is due to the contribution of the first two mechanisms electronic and nuclear stopping powers. Total electronic energy loss can further be subdivided into three main energy regions. They are (i) high energy region, (ii) intermediate energy region and (iii) low energy region. In the high energy region the velocity of a heavy charged particle is too high given by the formula v > v0Z12/3 (where v0 indicates c/137, here c is the velocity of the light)i.e. incident ion velocity is faster than the atomic electrons of the medium. According to the corrected Bethe formula electronic energy loss related to the medium through which HCPs travels and also on the velocity of the projectiles (Bethe 1930). This Bethe formula is not appropriate in the case of low ion velocities. In the low energy region the ion’s velocity is very low given by the formula v << v0Z12/3 and also the low energy region practically shows the neutrality to both target and projectile. In this region total stopping power is given with the help of the theory of Lindhard-Scharff (Lindhard and Scharff 1961). But in the intermediate energy region the total electronic energy loss can be predicted by the semi-empirical formula of Biersack and Haggmark (Biersack and Haggmark 1980) which is actually the combination of both Bethe and Lindhard-Schraff formulation.
Unveiling the principle descriptor for predicting the electron inelastic mean free path based on a machine learning framework
Published in Science and Technology of Advanced Materials, 2019
Xun Liu, Zhufeng Hou, Dabao Lu, Bo Da, Hideki Yoshikawa, Shigeo Tanuma, Yang Sun, Zejun Ding
As a starting point, the Bethe equation [28] for inelastic scattering was used in order to parameterize the IMFP data calculated or measured. All parameters of the equation are microscopic quantities. However, the original Bethe formula has an obvious shortcoming in that it is only valid for sufficiently high energies (above 200 eV).