Measurement of the Photoassociation Rate in a BEC of $^{7}$Li

Photoassociation is a process of producing molecules from a collision of two atoms. The maximum rate is limited by quantum mechanical unitarity and by a proposed mechanism involving photodissociation of bound molecules into the contiuum. In the unitarity limit, the rate scales as \textit{n}$\cdot$\textit{T}$^{- 0.5}$. In the photodissociation mechanism, the rate depends on coupling to the quasicontiuum resulting in saturation at high intensities at a value of $\hbar$\textit{n}$^{2/3}/\textit{m}.$\footnote{J. Javanainen and M. Mackie, \textit{Phys. Rev. A} \textbf{59}, R3186 (1999).} The rate of photoassociation has previously been observed to saturate in a non-condensed, but quantum degenerate sample of atomic $^7 $Li to a value consistent with the unitarity limit.\footnote{I. D. Prodan \emph{et al}., \textit{Phys. Rev. Lett.} \textbf{91}, 080402 (2003).} A Bose-Einstein condensate (BEC) is necessary to differentiate between unitarity and photodissociation. We will create a large BEC in an optical dipole trap in the \textit{F}=1, \textit{m}$_{F}$=1 hyperfine state in order to distinguish between these two proposed mechanisms.