Evidence for $b \to d \gamma$ Transitions Using a Sum of Exclusive Final States

Making use of a sum of exclusive final states with up to three charged pions and one neutral pion or eta, we have demonstrated that it is possible to measure the ratio of the inclusive rates $b\to d \gamma$ and $b \to s \gamma$. This provides information on $|V_{td}/V_{ts}|$ that is complementary to using the exclusive modes $B \to \rho \gamma$ and $B \to K^* \gamma$. These results are from an analysis of data collected by the BaBar detector at the PEP-II asymmetric-energy $e^+ e^-$ storage rings at SLAC.