  Background: In stars, carbon is produced exclusively via the $3\alpha$
process, where three $\alpha$ particles fuse to form $^{12}$C in the excited
Hoyle state, which can then decay to the ground state. The rate of carbon
production in stars depends on the radiative width of the Hoyle state. The
radiative width can be deduced by combining three separately measured
quantities, one of which is the $E0$ decay branching ratio. The $E0$ branching
ratio can be measured by exciting the Hoyle state in the $^{12}$C$(p,p')$
reaction and measuring the pair decay of its Hoyle state and first $2^+$ state.
  Purpose: To reduce the uncertainties in the carbon production rate in the
universe by measuring a set of proton angular distributions for the population
of the Hoyle state ($0^+_2$) and $2^+_1$ state in $^{12}$C in $^{12}$C$(p,p')$
reactions between 10.20 and 10.70 MeV, used in the determination of the $E0$
branching ratio of the Hoyle state.
  Method: Proton angular distributions populating the ground, first $2^+$, and
the Hoyle states in $^{12}$C were measured in $^{12}$C(p,p') reactions with a
silicon detector array covering $22^\circ<\theta<158^\circ$ in 14 energy steps
between 10.20 and 10.70 MeV with a thin ($60\ \mu$g/cm$^2$) $^{nat}$C target.
  Results: Total cross-sections for each state were extracted and the
population ratio between the $2^+_1$ and Hoyle state determined at each energy
step. By appropriately averaging these cross-sections and taking their ratio,
the equivalent population ratio can be extracted applicable for any thick
$^{12}$C target used in pair-conversion measurements.
  Conclusions: We present a general data set of high-precision $^{12}$C$(p,p')$
cross-sections that make uncertainties resulting from the population of the
$2^+_1$ and $0^+_2$ states by proton inelastic scattering negligible for any
future measurements of the $E0$ branching ratio in $^{12}$C.
