The beam commissioning of the 1.5 GeV electron storage ring of "NewSUBARU"
started in September 1998. At the beginning of the commissioning the beam l
ifetime was short because of the high beam-on pressure. The upgrade of the
vacuum system including the replacement of the vacuum chamber of the insert
ion devices and the addition of vacuum pumps was performed in 1999. As a re
sult of the upgrade the beam lifetime was drastically improved and the user
experiments started in February 2000. (C) 2001 Elsevier Science B.V. All r