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arXiv · 2505.11647

A cryogenic buffer gas beam source with in-situ ablation target replacement

Zhen Han·Zack Lasner·Collin Diver·Peiran Hu·Takahiko Masuda·Xing Wu·Ayami Hiramoto·Maya Watts·Satoshi Uetake·Koji Yoshimura·Xing Fan·Gerald Gabrielse·John M. Doyle·David DeMille
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Abstract

The design and performance of a cryogenic buffer gas beam (CBGB) source with a load-lock system is presented. The ACME III electron electric dipole moment (eEDM) search experiment uses this source to produce a beam of cold, slow thorium monoxide (ThO) molecules. A key feature of the apparatus is its capability to replace ablation targets without interrupting vacuum or cryogenic conditions, increasing the average signal in the eEDM search. The source produces approximately $1.3 \times 10^{11}$ ground-state ThO molecules per pulse, with a rotational temperature of $4.8$ K, molecular beam solid angle of $0.31$ sr, and forward velocity of $200$ m/s. These parameters match the performance of traditional sources that require time-consuming thermal cycles for target replacement. A long-term yield improvement of about 40% is achieved when the load-lock system is used to replace targets biweekly.

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Zhen Han, Zack Lasner, Collin Diver, Peiran Hu, Takahiko Masuda, Xing Wu, Ayami Hiramoto, Maya Watts, Satoshi Uetake, Koji Yoshimura, Xing Fan, Gerald Gabrielse, John M. Doyle, David DeMille. 2026-02-16. A cryogenic buffer gas beam source with in-situ ablation target replacement. https://arxiv.org/abs/2505.11647

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