  The finite mass of the heavy quark suppresses the collimated radiations,
which is generally referred to as the dead cone effect. In this paper, we study
the distribution of hadron multiplicity over the hadron opening angle with
respect to the jet axis in various flavors of jets. The corresponding
measurement can be the most straightforward and simplest to explore the
dynamical evolution of the radiations in the corresponding jet, which can
expose the mass effect. We also propose the transverse energy-weighted angular
distribution which sheds light on the interplay between perturbative and
nonperturbative effects in the radiation. With Monte-Carlo simulations, our
calculation shows that the dead cone effect can be clearly seen by taking the
ratio between the b jet and the light-quark (inclusive) jet, promising to be
measured at the LHC in the future.
