We propose a novel detection method for non-coherent synchronization in multi-access UWB impulse radio (IR) networks. It is designed to solve the IUI (Inter-User Interference) in particular the Near-Far scenario in the presence of concurrent UWB IR transmissions with multiple interfering transmitters, asynchronous transmissions and heterogeneous power levels, as can be found in ad-hoc networks. In such scenarios, the conventional synchronization method, which is based on correlating the received IR signal with a Template Pulse Train (TPT), does not always perform well. Our proposal has similar complexity as the conventional method. We evaluate its performance with the Line Of Sight (LOS) office indoor channel model proposed by the IEEE P802.15.4a study group and find that the improvement is very significant.