Abstract. We consider the adiabatic demagnetization in the rotating reference frame (ADRF) of a system of dipolar coupled nuclear spins s = 1/2 in the external magnetic field. The demagnetization starts with the offset of the external magnetic field (in frequency units) from the Larmor frequency being several times greater than the local dipolar field. For different subsystem sizes, we have found from numerical simulations the temperatures at which subsystems of a one-dimensional nine-spin chain and a plane nine-spin cluster become entangled. These temperatures are of the order of microkelvins and are almost independent of the subsystem size. There is a weak dependence of the temperature on the space dimension of the system.

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In recent years, the spin-temperature theory has been extended to multiplepulse NMR /1, 2/. In particular, the equations of saturation have been obtained /2/ for a pulsed version of the spin locking. However, the thermal mixing of the Zeeman and dipole-dipole (DD) interaction reservoirs (dipole-Zeeman c r o s s relaxation -DZCR) has not beenincluded in these equations.In this paper, the evolution of the magnetization is considered in the pres-

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