FLUORESCENCE DETECTION TOWARDS LASER SPECTROSCOPY OF CESIUM ATOMS UNDER PRESSURE-VARIABLE SUPERFLUID HELIUM ENVIRONMENT

Hyperfine structure energy splitting of atoms in superfluid helium (He II) is known to be slightly different from that in vacuum. We have been developing a pressure-variable cell for laser-RF/MW double resonance spectroscopy of Rb and Cs atoms in He II to measure the variation of hyperfine structure energy splitting with varied pressure to elucidate interaction of atoms with He II.In this study we aim at verification of detection system of laser-induced fluorescence (LIF) by photon counting method using photomultiplier tube (PMT), and performance evaluation of external cavity laser diode (ECLD) prepared as pumping source for Cs atoms as preliminary experiments. We here report detection of LIF from Cs atoms in gas cell and spin polarization using photon counting method towards double resonance experiments