Single-Photon Atomic Cooling - Raizen Lab - The University of ...

2.1 Rubidium
Rubidium (Rb) is an alkali metal. Its common use in atomic exper-
iments is due in part to its relatively simple energy level structure and its
possession of an accessible effective cycling transition. The simplicity of the
energy level structure is due to the fact that of Rb’s 37 electrons only one is
in the outermost shell. 85 Rb is the most abundant and only stable isotope
of rubidium, however the experimental work performed in this dissertation
was done entirely on 87 Rb. The reason for this is that 87 Rb has a simpler
hyperfine structure, the topic of the next section. 87 Rb has a relative natural
abundance of 27.83(2)% and decays to β − + 87 Sr with a total disintegration
energy of 0.283 MeV [40]. While unstable, the nuclear lifetime is 4.88×10 10 yr
[40] making this form of rubidium effectively stable over the duration of our
experiment. The mass of 87 Rb was accurately determined from a Penning trap
measurement to be m = 1.443 160 648(72) × 10 −25 kg [41]. The vapor pressure
of solid Rb is an important experimental quantity because it dictates the load-
ing rate into the first stage of our experimental procedure. This value can be
taken from a vapor-pressure model for solid Rb given by [42], which is
log10Pv = 2.881 + 4.857 − 4215
, (2.1)
T
where Pv is the vapor pressure in torr and T is in K. This model is specified to
have an accuracy better than ±5% from 298-550K. The ambient temperature
surrounding our experimental chamber is approximately 295K resulting in a
vapor pressure of 2.9 × 10 −7 torr. More will be said about how this relates
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