The construction of the 25-m long undulator of in-vacuum type was finished
successfully and installed into the 30-m straight section of the SPring-8 s
torage ring. The period length is 32 mm and the number of periods is 780. T
he maximum field is obtained as 0.59 T at the minimum gap of 12 mm. Althoug
h this device is composed of five segments, it works as a one-piece undulat
or without any phasing system. Following this long device, the in-vacuum re
volver undulator of mini-gap type will soon be completed. This device has f
our undulators with different period length. (C) 2001 Elsevier Science B.V.
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