Trap laser (6 mW - 1 cm diameter) x 6 -  /2 detuned to 171Yb 1P1 oven Zeeman slower Trapped atom number Lens f=7.5 cm, diameter d=2.54 cm PMT = 5 v con = 0.3 V Power meter = 0.3  W D=15 cm

oven Zeeman slower Flux measurement Trap laser (6 mW - 1 cm diameter) x 2 0 Hz detuned to 171 Yb 1P1 PMT = ~ 2 v con = V Fluorescent power of atomic beam is too weak to be measured by power meter, thus a calibrated PMT was used. Calibration reference PMT = 5 v con = V  P = 0.3 W However PMT gain varies with control voltage, thus PMT gain with control voltage was measured.

PMT gain with control voltage PMT voltage (V) is normalized to be 1 volt when control voltage is 0.2 V

Mixture of thermal and slowed atoms Thermal atoms 1Thermal atoms 2Non-atomic scattering Probe laseroooo Magnetic fieldoxoo Zeeman slowing laserooxo Atomic beamooox PMT voltage (v) V What was measured is the number of atoms inside interaction volume. 2. What is to be measured is the loading rate of MOT, which is the flux of atomic beam. 3.Flux is always preserved while the speed of atoms vary with Zeeman slower. 4.Flux varies only with oven temperature. 5.The number of atoms inside interaction volume varies with the speed of atoms. Atomic beam fluorescence

Total number of atoms interacting with probe laser F is flux of atomic beam : N cm -2 s -1 A is area of interaction L is interacting length v is velocity of atoms Density of atoms interacting with probe laser n=N/cm -3

PMT signal : 2 v con =0.608 V  v con =0.300 V  W

3.2 % of atoms are trapped. Atoms may defuse out by Zeeman slower. Only a small fraction of slowed atoms can reach MOT region. Loading rate from MOT experiment

Zeeman slowed Atom density Mixture of thermal and slowed atoms Thermal atoms 1Thermal atoms 2Non-atomic scattering Probe laseroooo Magnetic fieldoxoo Zeeman slowing laserooxo Atomic beamooox PMT voltage (v) V Assume v slow =30 m/s V mp =300 m/s