ZEPLIN (for Zoned Proportional Scintillation in Liquid Noble Gases) is a name used for experiments to detect dark matter, in particular, some theorized WIMPs. The aim is to detect electromagnetic radiation from a noble gas (specifically, xenon) and the detector consists of a tank of such an element, but cooled to its liquid state. Noble gases are of particular use because of the EMR they produce from very small interactions with other particles. The term WIMP represents a particle presumed to have a very small cross section for interactions with baryonic matter and the more gas in the detector, the more such interactions would occur. Shielding against as many "normal" particles as practical is advantageous. Very sensitive photometers, e.g., photomultiplier tubes are used to detect any resulting EMR.
Four such experiments have been titled with the acronym ZEPLIN: ZEPLIN-I, ZEPLIN-II, ZEPLIN-III in England, and LUX-ZEPLIN (aka LZ, the abbreviation LUX standing for "large underground xenon") in the USA. They have not found WIMPs but have yield evidence about possible cross sections.