Modulation effect in the differential and total rate for supersymmetric dark matter detection

The modulation effect in the direct detection of supersymmetric cold dark matter (CDM) particles is investigated. A variety of nuclear targets (light, intermediate and heavy) are considered, taking into account the nuclear form factor effects and detector energy thresholds. It is shown that the nuclear form factor tends to decrease the modulation effect in the total event rate below its typical value of 5%. In spite of this, however, in some subregions of phase space, the modulation effect can become much larger, $h<~25\%.$ It also becomes more pronounced in the differential event rate in some domains of the energy transfer. These effects may be exploited to discriminate against background.