A singularity in E1 matrix elements at the neutron threshold: Evidence from (d, p)-(n, γ) correlations

There are several independent effects which tend to suppres correlations of (d, p)-(n, γ) type. When a near-perfect correlation is found, as in the case ³⁷Cl with thermal capture, it follows that all the effects are small. This has important implications, such as showing that the dominant thermal capture process can be `direct', thereby settling a long debate. Further, the data establishes the E_γ^-1 singularity in E1 matrix elements for thermal capture that was derived theoretically in 1960.