Riken Corporation

Ichiro Ushijima

Hideo Yokota

Hidetoshi Katori

Masao Takamoto

Takehiro Tawara

Provided according to an embodiment of the present disclosure is a radiation shieldincluding a shield wall surrounding a hollow region capable of accommodating therein atoms for an optical lattice clock, the shield wall having, provided therein, at least two apertures communicating with outside. A geometrical shape of an inner wall surface of the shield wall is configured such that a difference between BBR shifts found under two conditions does not exceed a predetermined value over a range of position of atoms, the BBR shifts being caused in atomsby emitted radiation emitted by the inner wall surface, incoming radiation leaking in from the outside through the apertures, and a reflection component of the emitted radiation and incoming radiation at the inner wall surface, the two conditions being a condition where the inner wall surface exhibits mirror reflection and a condition where the inner wall surface exhibits diffuse reflection, the range being where clock transition operation is carried out in the optical lattice clock, the inner wall surface facing the hollow region. Provided according to other embodiments of the present disclosure also are the optical lattice clockincluding such a radiation shield, and a design method for the radiation shield.

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Wako, Japan

Ichiro Ushijima