# Where is the “Bremsstrahlung” before the annihilation of an electron and a positron?

When an electron and a positron meet, they annihilate each other, converting into two gamma rays. Unless all of them hit in a straight line (very unlikely), they should emit Bremsstrahlung before the collision, but I think this is not observed. Can someone explain why the Bremsstrahlung is missing?

• Would be hard to measure against the background of Compton radiation from the annihilation gammas. – Pieter Feb 13 '18 at 12:01
• Any spectrometer should be able to distinguish the gamma rays from other radiation. Why should this be hard? – Johannes Maria Frank Feb 13 '18 at 12:37
• Because of the overlap with the Compton continuum caused by the annihilation gammas. At te same energy, spectroscopy cannot help you to distinguish these from a bremsstrahlung continuum. – Pieter Feb 13 '18 at 12:47
• Even if this is the case, the Bremsstrahlung should be emitted before the gamma rays are emitted. Thus it should be detectable. – Johannes Maria Frank Feb 13 '18 at 12:50

• @JohannesMariaFrank My understanding is that observing the Rydberg spectrum of positronium is a tricky measurement, but it has certainly been done. But you shouldn't think that there is some fixed set of decay steps that must occur before annihilation. The hydrogen-like wave-function is non-zero for zero separation in all s-states, which means that annihilation can occur for any value of $n$ or even for an un-bound pair. – dmckee Feb 13 '18 at 19:47