Thallium zirconium chloride (Tl₂ZrCl₆) and its hafnium analog (Tl₂HfCl₆) are intrinsic scintillators that have been recently reported, primarily for gamma-ray detection and spectroscopy. These crystals are especially useful for dual-mode detection, gammas exploiting the highly effective $Z$ of the materials, and fast neutrons using the (n, p) and (n, $\alpha$ ) reactions with chlorine. $Z_{\mathrm {eff}}$ (70.7) and high photoelectric conversion efficiency of the zirconium variant without any activator makes it particularly attractive in this regard. We report here on the growth of undoped Tl₂ZrCl₆ and Tl₂HfCl₆ crystals using vertical Bridgman technique. The X-ray emission spectrum shows a broadband in the range of 400–600 nm with a peak around 470 nm for both crystals. The light yields (LYs) of these crystals were measured under irradiation by a ¹³⁷Cs gamma source (662 keV) and compared with that from the commercial Tl-doped NaI crystal. Normalized for the quantum efficiency of the photomultiplier (PMT) at the relevant emission wavelengths, the respective LYs of Tl₂ZrCl₆ and Tl₂HfCl₆ are estimated to be 40 000 and 18 000 photons/MeV with corresponding energy resolution of 5% and 9%, respectively. We have demonstrated for the first time the neutron detection capability of these materials showing excellent pulse shape discrimination (PSD) with figure of merit on the order of 2.4. PSD measurement of Tl₂ZrCl₆ using a ²⁴¹AmBe source demonstrates well-separated gamma, recoiled proton, and alpha particle bands.

中文翻译：

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用于伽马射线和快速中子探测的 Tl2ZrCl6 和 Tl2HfCl6 本征闪烁体

铊锆氯化物 (Tl ₂ ZrCl ₆ ) 及其铪类似物 (Tl ₂ HfCl ₆ ) 是最近报道的本征闪烁体，主要用于伽马射线检测和光谱学。这些晶体对于双模式检测特别有用，伽马利用高效的 $Z$ 材料和快中子使用 (n, p) 和 (n, $\alpha$ ) 与氯反应。 $Z_{\mathrm {eff}}$ (70.7) 和不含任何活化剂的锆变体的高光电转换效率使其在这方面特别有吸引力。我们在此报告了使用垂直 Bridgman 技术生长未掺杂的 Tl ₂ ZrCl ₆和 Tl ₂ HfCl ₆晶体。X 射线发射光谱显示了 400-600 nm 范围内的宽带，两种晶体的峰值都在 470 nm 左右。在¹³⁷ Cs 伽马源 (662 keV) 的照射下测量这些晶体的光产额 (LYs)并与商业 Tl 掺杂的 NaI 晶体的光产额进行比较。归一化光电倍增管 (PMT) 在相关发射波长下的量子效率，Tl ₂ ZrCl的各自 LY₆和 Tl ₂ HfCl ₆估计为 40 000 和 18 000 光子/MeV，相应的能量分辨率分别为 5% 和 9%。我们首次证明了这些材料的中子探测能力，显示出优异的脉冲形状鉴别 (PSD)，品质因数约为 2.4。使用²⁴¹ AmBe 源对 Tl ₂ ZrCl _{6 的}PSD 测量表明分离良好的伽马、反冲质子和 α 粒子带。