Stopping power of TGS crystals for proton beam at ferro-paraelectric phase transition.

Experimental study on stopping power of ferroelectric Tryglycine Sulphate (TGS) single crystal for 24.779 MeV protons was carried out as a function of the temperature of TGS with an accuracy of 0.05%. The stopping power of the TGC crystal shows broad valleys in ferroelectric region when the proton beam is moving along the ferroelectric b-axis (010). The fluctuations with peak-peak variation of 0.3% - 0.6% for proton beam near the Curie temperature T_C is observed. This variation in the ferroelectric region cannot be contributed to the dielectric constant of the medium. The electric field and the localized temperature due to passage of proton beam may cause the switching and pining of the domains. The domain switching time τ_s depends on the transverse electric field and sample thickness. The thermal spike model is used to estimate the increase in the localized temperature due to passage of 24.779 MeV Protons in ferroelectric TGS crystal. In this paper, the experimental method of measuring stopping power of TGS crystal for proton beam, interpretation of the results in terms of (i) increase in localized temperature of the crystal sample using thermal spike model, (ii) the transverse electric field developed in the crystal sample and (iii) the domain switching time to account the observed experimental fluctuations in stopping power of TGS crystal for proton beam is discussed. [ABSTRACT FROM AUTHOR]