Vertical gradient freeze (VGF) technique as a cost-effective method for growth of trans-stilbene scintillator crystal and investigation of its structural, optical, and alpha – gamma scintillation characteristics

Trans -Stilbene is a promising organic scintillator for radiation detection owing to its fast response and pulse-shape discrimination capability. In this work, a stationary-ampoule vertical gradient freeze (VGF) technique was employed to grow a centimeter-scale trans-stilbene single crystal, followed by systematic investigation of its structural, optical, luminescence, mechanical, and scintillation properties. Powder X-ray diffraction, Laue diffraction, and single-crystal X-ray diffraction confirmed a monoclinic P2 1 /c structure without detectable twinning. The crystal exhibited ~75% optical transmission in the UV‐Vis-NIR region and an Urbach energy of 88.8 meV. Photoluminescence showed characteristic emission, while time-resolved measurements revealed decay components of 1.29 and 3.47 ns. Under gamma excitation, a light yield of ~23,141 Photons/MeV was estimated using an EJ-276D reference scintillator. Alpha excitation using 239 Pu/ 241 Am yielded an energy resolution of ~26%, quenching factor of 7.9%, and light yield of ~1166 Photons/MeV. The scintillation decay profiles exhibited bi-exponential behavior, with fast and slow components of 7.00 ± 0.08 and 131.30 ± 7.37 ns for gamma excitation, contributing 87.8% and 12.2%, respectively, while alpha excitation yielded corresponding components of 9.76 ± 0.15 and 148.04 ± 3.23 ns with contributions of 55.1% and 44.9%. This enabled gamma/alpha pulse shape discrimination with a figure of merit of 2.92. Birefringence interferometry and Vickers microhardness further characterized the crystal. These results demonstrate the feasibility of stationary-ampoule VGF for growing large trans-stilbene crystals and its potential as a simple and cost-effective route for organic scintillator materials for radiation detection.