MANUFACTURING METHOD FOR COLD HEAD

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PROBLEM TO BE SOLVED : To provide a manufacturing method for a cold head using a cold storage material which prevents a reduction in freezing capacity due to a secular change, improves mechanical strength and has high long-term reliability. SOLUTION : A manufacturing method for a cold head of one embodiment comprises : a step of preparing at least one cold storage container 3; and a step of filling the cold storage container 3 with a plurality of cold storage material particle groups 1-1 and 1-2 of which kinds are different. Cold storage material particles constituting at least one of the plurality of cold storage material particle groups are rare earth cold storage material particles containing rare earth elements as constituents, and a peak indicating carbon components is detected on each surface area of the rare earth cold storage material particles by X-ray photoelectron spectrometry. An entire carbon content including the carbon components of the rare earth cold storage material particles is equal to 100 mass ppm or less. Each carbon component has at least one kind selected from a C-C bond, a C-H bond, a C-O bond, a C=O bond and an O-C=O bond. SELECTED DRAWING : Figure 2 COPYRIGHT : (C)2019, JPO&INPIT