Recent improvements of NICT atomic fountains CsF1 & CsF2

NICT atomic fountains CsF1 and CsF2 and their frequency reference based on a cryogenic sapphire oscillator (CSO) are being upgraded with aiming at operations at the low 10
^-16
level. The CSO was upgraded from “dewar-type” to “cryocooler-type” and a long-term continuous operation became available without routine liquid helium transfer. A rapid adiabatic passage method was installed to the fountain in order to correct for a collision shift precisely. The temperature control for the main chamber started to reduce uncertainties of shifts related to the blackbody radiation and the microwave cavity. Other improvements are being undertaken.