To measure the cross section of the 12C(α, p) 15N reaction of Example 13.2, a detector s...

To measure the cross section of the ¹²C(α, p) ¹⁵N reaction of Example 13.2, a detector subtending a solid angle of 3 × 10^-3 sr is used at the scattering angle θ. A 0.20- μA beam of 14.6-MeV particles is incident on a ¹²C target of thickness 100 μg/cm² for one hour. If the differential cross section is 0.25 mb/sr, how many protons are detected at the angle θ?