abstract: Given any knot $K$ and integer $n$, we form the $n$-trace $Xn(K)$ by attaching an $n$-framed 2-handle to the 4-ball along $K$. We will show that for any choice of $n \geq 0$, the oriented diffeomorphism type of $Xn(K)$ determines the hat Heegaard Floer homologies of all nonnegative rational surgeries on $K$. We will then use this to show that every torus knot is detected by its 0-trace. This is joint work with John Baldwin.