  Usual uniformly accelerated frame, in Dray-'t Hooft spacetime, does not see
the any quantum imprint on Unruh effect due to localised shock wave in
Minkowski spacetime. Here we argue that such non-appearance of quantum memory
is specific to those particular observers which do not incorporate the presence
of wave in their trajectory. In fact a detector, associated with a frame which
is affected by the shock, can not be trivial in terms of its response. We
explicitly show that the later type of frame detects particle in the shock wave
Minkowski vacuum which is the effect of shock. Therefore this quantum memory is
very special to specific class of observers as far as Dray-'t Hooft spacetime
is concerned. We analyse for a null like trajectory along which the detector is
moving.
