  A study of $\chi_{b}$ meson production at LHCb is performed on proton-proton
collision data, corresponding to 3.0fb$^{-1}$ of integrated luminosity
collected at centre-of-mass energies $\sqrt{s}=7$ and 8TeV. The fraction of
$\Upsilon(nS)$ mesons originating from $\chi_{b}$ decays is measured as a
function of the $\Upsilon$ transverse momentum in the rapidity range $2.0 <
y^{\Upsilon} < 4.5$. The radiative transition of the $\chi_{b}(3P)$ meson to
$\Upsilon(3S)$ is observed for the first time. The $\chi_{b1}(3P)$ mass is
determined to be $$m(\chi_{b1}(3P)) = 10\,511.3 \pm 1.7 \pm 2.5 MeV/c^2,$$
where the first uncertainty is statistical and the second is systematic.
