Growth and characterization of thorium-doped calcium fluoride single crystals

2022/11/10 by Kjeld Beeks, Tomáš Šikorský, Beeks, Kjeld +29 · 5 citations
Engineering · Physics and Astronomy · #Advanced Semiconductor Detectors and Materials #Atomic Physics (physics.atom-ph) #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Nuclear Experiment (nucl-ex) #Nuclear Physics and Applications #Radiation Detection and Scintillator Technologies

paper · pdf · doi:10.48550/arxiv.2211.05445

openalex publication_date 2022/11/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We have grown ²³²Th:CaF₂ and ²²⁹Th:CaF₂ single crystals for investigations on the VUV laser-accessible first nuclear excited state of ²²⁹Th. To reach high doping concentrations despite the extreme scarcity (and radioactivity) of ²²⁹Th, we have scaled down the crystal volume by a factor 100 compared to established commercial or scientific growth processes. We use the vertical gradient freeze method on 3.2 mm diameter seed single crystals with a 2 mm drilled pocket, filled with a co-precipitated CaF₂:ThF₄:PbF₂ powder in order to grow single crystals. Concentrations of 4⋅10¹⁹ cm^-3 have been realized with ²³²Th with good (>10%) VUV transmission. However, the intrinsic radioactivity of ²²⁹Th drives radio-induced dissociation during growth and radiation damage after solidification. Both lead to a degradation of VUV transmission, limiting the ²²⁹Th concentration to <5⋅10¹⁷ cm^-3.

Cited by

• Towards theory constraints on ultralight dark matter from quantum gravity
• Laser Mössbauer spectroscopy of ²²⁹Th
• A continuous-wave vacuum ultraviolet laser for the nuclear clock
• Density Functional Theory Study of Th-doped LiCAF and LiSAF for Nuclear Clock Applications
• Discrimination of metric theories

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