Crystal growth and luminescence properties of organic crystal scintillators for α-rays detection

摘要

Scintillation and luminescence properties of a novel organic crystal scintillator, 1,4-bis(2-methylstyryl) benzene (bis-MSB), were measured and compared with those of the conventional trans-stilbene organic crystal scintillator. Although trans-stilbene has been used for beta or neutron detection, trans-stilbene cannot be applied at high temperature conditions due to a lower melting point (124 degrees C). Liquid scintillators or plastic scintillators also cannot be used at high temperature. Usually, bis-MSB has been used as dopant in liquid scintillators to obtain fast scintillation'decay and high luminescence quantum yield, and its melting point is 181 degrees C higher than that of trans-stilbene. In this paper, we focused on bis-MSB in solid state. The bis-MSB and trans-stilbene crystals were grown by the self-seeding vertical Bridgman method using double quartz ampoules. The bis-MSB crystal had the fast decay time of similar to 4.2 ns and the increased light yield of similar to 12,000 ph/5.5 MeV(alpha), while trans-stilbene had the decay time of similar to 8.5 ns and the light yield of similar to 8500 ph/5.5 MeV(alpha). The photoluminescence quantum yield was almost constant up to 125 degrees C for bis-MSB and only up to 50 degrees C for trans-stilbene. We succeeded in obtaining the novel organic crystal scintillator which can operate even at higher temperature up to 125 degrees C.