Pinpointing a pulsar in its parent supernova remnant ( SNR ) or resulting pulsar wind nebula ( PWN ) is key for understanding its formation history , and the pulsar wind mechanism .
Yet , only about half the SNRs and PWNe appear associated with a pulsar .
We aim to find the pulsars in a sample of eight known and new SNRs and PWNe .
Using the LOFAR radio telescope at 150 MHz , each source was observed for 3 hours .
We covered the entire remnants where needed , by employing many tied-array beams to tile out even the largest objects .
For objects with a confirmed point source or PWN we constrained our search to those lines of sight .
We identify a promising radio pulsar candidate towards PWN G141.2+5.0 .
The candidate , PSR J0337+61 , has a period of 94 ms and a DM of 226 pc cm ^ { -3 } .
We re-observed the source twice with increased sensitivities of 30 % and 50 % but did not re-detect it .
It thus remains unconfirmed .
For our other sources we obtain very stringent upper limits of 0.8 - 3.1 mJy at 150 MHz .
Generally we can rule out that the pulsars travelled out of the remnant .
From these strict limits we conclude our non-detections towards point-sources and PWNe are the result of beaming and propagation effects .
Some of the remaining SNRs should host a black hole rather than a neutron star .