A method for background reduction in an experiment for WIMP search with a Xe(Ar)-liquid ionization chamber

A detection method for UV-photons from Xe ₂^∗ deexcitation with ∼ 100% efficiency is proposed. This allows to distinguish reliably the Xe(Ar) recoil nuclei from background electrons. As a result of this the β- and γ-backgrounds will be suppressed practically completely. The neutron background can be reduced by water shielding and by making the experiment deep underground. The body of a chamber 636 mm in diameter and 1000 mm long is now prepared for this experiment. About 35-70 liters of liquid Xe will be used in this chamber. A background of about 10 ^-5 events (kg day) ^-1 can be obtained in this experiment.