A method to detect the VUV photons from cooled $^{229}$Th:CaF$_2$ crystals

Fuente: arXiv
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Main Authors: Guan, Ming, Bartokos, Michael, Beeks, Kjeld, Fukunaga, Yuta, Hiraki, Takahiro, Masuda, Takahiko, Miyamoto, Yuki, Okage, Ryoichiro, Okai, Koichi, Sasao, Noboru, Schaden, Fabian, Schumm, Thorsten, Shimizu, Koutaro, Takatori, Sayuri, Yoshimi, Akihiro, Yoshimura, Koji
Format: Preprint
Published: 2024
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author Guan, Ming
Bartokos, Michael
Beeks, Kjeld
Fukunaga, Yuta
Hiraki, Takahiro
Masuda, Takahiko
Miyamoto, Yuki
Okage, Ryoichiro
Okai, Koichi
Sasao, Noboru
Schaden, Fabian
Schumm, Thorsten
Shimizu, Koutaro
Takatori, Sayuri
Yoshimi, Akihiro
Yoshimura, Koji
author_facet Guan, Ming
Bartokos, Michael
Beeks, Kjeld
Fukunaga, Yuta
Hiraki, Takahiro
Masuda, Takahiko
Miyamoto, Yuki
Okage, Ryoichiro
Okai, Koichi
Sasao, Noboru
Schaden, Fabian
Schumm, Thorsten
Shimizu, Koutaro
Takatori, Sayuri
Yoshimi, Akihiro
Yoshimura, Koji
contents Thorium-229, with its exceptionally low-energy nuclear excited state, is a key candidate for developing nuclear clocks. $^{229}$Th-doped CaF$_2$ crystals, benefiting from calcium fluoride's wide band gap, show great promise as solid-state nuclear clock materials. These crystals are excited by vacuum ultraviolet (VUV) lasers, which over time cause radiation damage. Cooling the crystals can mitigate this damage but introduces a challenge: photoabsorption. This occurs when residual gas molecules condense on the crystal surface, absorbing VUV photons and deteriorating detection efficiency. To solve this, we developed a cooling technique using a copper shield to surround the crystal, acting as a cold trap. This prevents ice-layer formation, even at temperatures below $-100\,^\circ$C, preserving high VUV photon detection efficiency. Our study detailed the experimental cooling setup and demonstrated the effectiveness of the copper shield in maintaining crystal performance, a critical improvement for future solid-state nuclear clocks operating at cryogenic temperatures.
format Preprint
id arxiv_https___arxiv_org_abs_2410_18134
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A method to detect the VUV photons from cooled $^{229}$Th:CaF$_2$ crystals
Guan, Ming
Bartokos, Michael
Beeks, Kjeld
Fukunaga, Yuta
Hiraki, Takahiro
Masuda, Takahiko
Miyamoto, Yuki
Okage, Ryoichiro
Okai, Koichi
Sasao, Noboru
Schaden, Fabian
Schumm, Thorsten
Shimizu, Koutaro
Takatori, Sayuri
Yoshimi, Akihiro
Yoshimura, Koji
Instrumentation and Detectors
Nuclear Experiment
Thorium-229, with its exceptionally low-energy nuclear excited state, is a key candidate for developing nuclear clocks. $^{229}$Th-doped CaF$_2$ crystals, benefiting from calcium fluoride's wide band gap, show great promise as solid-state nuclear clock materials. These crystals are excited by vacuum ultraviolet (VUV) lasers, which over time cause radiation damage. Cooling the crystals can mitigate this damage but introduces a challenge: photoabsorption. This occurs when residual gas molecules condense on the crystal surface, absorbing VUV photons and deteriorating detection efficiency. To solve this, we developed a cooling technique using a copper shield to surround the crystal, acting as a cold trap. This prevents ice-layer formation, even at temperatures below $-100\,^\circ$C, preserving high VUV photon detection efficiency. Our study detailed the experimental cooling setup and demonstrated the effectiveness of the copper shield in maintaining crystal performance, a critical improvement for future solid-state nuclear clocks operating at cryogenic temperatures.
title A method to detect the VUV photons from cooled $^{229}$Th:CaF$_2$ crystals
topic Instrumentation and Detectors
Nuclear Experiment
url https://arxiv.org/abs/2410.18134