Preliminary Evaluation of the Cesium Fountain Primary Frequency Standard NMIJ-F2. - Akifumi Takamizawa; Shinya Yanagimachi; Takehiko Tanabe; Ken Hagimoto; Iku Hirano; Ken-ichi Watabe; Takeshi Ikegami; John G. Hartnett (IEEE Trans. Instrum. Meas., 2015)