The quantum statistics of bosons or fermions are manifest through even or odd relative angular momentum of a pair. We show theoretically that, under certain conditions, a pair of certain test particles immersed in a fractional quantum Hall state possesses, effectively, a fractional relative angular momentum, which can be interpreted in terms of fractional braid statistics. We propose that the fractionalization of the angular momentum can be detected directly through the measurement of the pair correlation function in rotating ultra-cold atomic systems in the fractional quantum Hall regime. Such a measurement will also provide direct evidence for the effective magnetic field resulting from Berry phases arising from attached vortices, and of excitations with fractional particle number, analogous to fractional charge of electron fractional quantum Hall effect.PACS numbers: 03.65. Vf,03.75.Mn, While all particles in nature are either bosons or fermions, emergent particles in strongly correlated condensed matter systems can, in principle, obey fractional braid statistics [1,2], which refers to the property that their braiding produces phases that are non-integral multiples of 2π. It was proposed three decades ago [3,4] that the fractional quantum Hall effect [5] (FQHE) provides a platform for the realization of such entities. No convincing measurement of the fractional braid statistics has yet been made. In this Letter we consider a pair of test atoms in a background FQHE state of bosonic atoms. Under certain conditions, the test atoms capture vortices and the bound states of atoms and vortices behave effectively as particles with fractional braid statistics. Just as fermionic or bosonic statistics are reflected through an odd or even integer relative angular momentum for a pair of particles, fractional braid statistics are manifest through fractional relative angular momentum. We further show that the relative angular momentum can be deduced from the pair correlation function through determination of the radii of various quantized orbits of one test particle around another. This provides a method for measuring fractional braid statistics relying only on already existing experimental methods of introducing test atoms as well as of measuring their pair correlation function in ultra-cold bosons in rapidly rotating optical traps. No direct interferometric or phase measurement is necessary. In addition, our proposed experiment will provide a direct measurement of the effective magnetic field arising from a binding of vortices to bosons, as well as of excitations involving a fraction of a boson.Neutral bosons can in principle be driven into the FQHE regime by rapid rotation, which effectively amounts to application of a magnetic field. The strongly interacting regime is reached as the number of vortices (N V ) in a rotating Bose-Einstein condensate becomes comparable with the number of atoms N , which is parametrized by the filling factor ν = N/N V . Various methods have been developed for producing vorticity in atomic Bo...