<p>A well tool (10) for determining the presence or absence of cement in an annular area between two concentric pipes in a hydrocarbon well comprises a tool housing (1 1) and a pulse generator (14) provided within the tool housing (1 1) for generating a magnetic field. The pulse generator (14) comprises an inductor (Ls) and a power supply device (HV, c) for supplying electrical power to the inductor (L) and thereby generating an electromagnetic pulse in such a way that, in use, the electromagnetic pulse provides physical vibrations in the pipe being closest to the pulse generator (14). The well tool further comprises at least one signal recorder (16) provided within the tool housing (1 1) for recording reflected acoustic signals from the well. A first distance (HI) between the signal recorder (16) and the pulse generator (14) is substantially equal to a second distance (H2) between the pulse generator (14) and the annular area.</p>
