  The unstable radium nucleus is appealing for probing new physics due to its
high mass, octupole deformation and energy level structure. Ion traps, with
long hold times and low particle numbers, are excellent for work with
radioactive species, such as radium and radium-based molecular ions, where low
activity, and hence low total numbers, is desirable. We address the challenges
associated with the lack of stable isotopes in a tabletop experiment with a
low-activity ($\sim 10 \ \mu\mathrm{Ci}$) source where we laser-cool trapped
radium ions. With a laser-cooled radium ion we measured the $7p\ ^2P_{1/2}^o$
state's branching fractions to the ground state, $7s\ ^2S_{1/2}$, and a
metastable excited state, $6d\ ^2D_{3/2}$, to be $p=0.9104(7)$ and $0.0896(7)$,
respectively. With a nearby tellurium reference line we measured the $7s\
^2S_{1/2} \rightarrow 7p\ ^2P_{1/2}^o$ transition frequency, 640.09663(6) THz.
