ZEPLIN IV: A 1-Ton Very Sensitive ZEPLIN II Extension for SUSY Dark Matter

We present a concept of a one ton two-phase liquid Xenon detector based on the concept of the ZEPLIN II detector currently under construction by a UCLA/Torino/UKDM team. The ZEPLIN II detector may be installed in the Boulby laboratory early in 2002. The one ton detector design will benefit from the initial operations of ZEPLIN II.