Solution growth and scintillation properties of 9-phenylcarbazole

Abstract

In this paper we report on the crystal growth and characterization of 9-phenylcarbazole (PCz). Crystals of PCz were obtained by the solution growth technique. Several organic solvents were investigated including heptane, cyclohexane, toluene, xylene, methanol, ethanol, and acetone. The largest crystals of the highest quality were grown from acetone.Radioluminescence spectra of pure PCz crystals exhibit a broad emission band peaking at 381 nm. Adding a small amount of an impurity (dopant) shifts the emission wavelength to 446 nm which is a better match to standard bialkali photomultiplier tubes. Single crystals of pure PCz have low light yields (typically < 5,000 ph/MeV), but doped crystals show high light yields of up to 25,000 ph/MeV and have a fast scintillation decay of less than 20 ns. Pulse shape discrimination with doped PCz crystals using neutron and gamma-rays from a 252Cf source yields a Figure of Merit (FOM) of about 2.7 at 1.0 MeVee cut-off energy.As far as we are aware, doped PCz is one of the brightest organic single crystal scintillators in existence and is a very promising organic neutron detector for a multitude of applications including homeland security, nuclear non-proliferation, nuclear physics, and non-destructive testing.