Titanium Purification System for LUX

The Large Underground Xenon (LUX) experiment is a large collaborative effort to detect Weakly Interacting Massive Particles (WIMP), which are the current leading candidates for what dark matter consists of.  The LUX detector is essentially a large container of liquid Xenon, which can detect collisions between the Xe and WIMPS by measuring the scintillation and ionization energy released because of these collisions.  Unfortunately, impurities in the Xe container can absorb this ionization signal.  Currently, the Xe is purified by boiling if off, passing it through a getter (a reactive substance that combines with impurities), and then bringing it back down to liquid form.  While effective, this process assumes that impurities in the container will boil off with the Xe, and requires the 350 kg of liquid to be boiled.  If getter material could be produced through a very powerful spark, the Xe could pass through a purification chamber containing the getter material while remaining in liquid form.  We have constructed such a device (known as a spark getter) using Titanium plates.  When a very high voltage is applied to the Titanium plates, a powerful spark arcs across the two plates, and simultaneously strips some small Titanium particles off.  This process is repeated until there are many small Titanium particles inside the purification chamber.  The Xe can then flow through our purification chamber, and the Titanium will attach itself to impurities.  When there are no Titanium particles left to purify, the voltage is simply reapplied, and new gettering material is produced.