  In recent years cooling technology for Liquid Xenon (LXe) detectors has
advanced driven by the development of Dark Matter (DM) detectors with target
mass in the 100 - 1,000 kg range. The next generation of DM detectors based on
LXe will be in the 50,000 kg (50 t) range requiring more than 1 kW of cooling
power. Most of the prior cooling methods become impractical at this level. For
cooling a 50 t scale LXe detector, a method is proposed in which Liquid
Nitrogen (LN$_2$) in a small local reservoir cools the xenon gas via a cold
finger. The cold finger incorporates a heating unit to provide temperature
regulation.
  The proposed cooling method is simple, reliable, and suitable for the
required long-term operation for a rare event search. The device can be easily
integrated into present cooling systems, e.g. the 'Cooling Bus' employed for
the PandaX I and II experiments. It is still possible to cool indirectly with
no part of the cooling or temperature control system getting in direct contact
with the clean xenon in the detector. Also the cooling device can be mounted at
a large distance, i.e. the detector is cooled remotely from a distance of 5 -
10 m. The method was tested in a laboratory setup at Columbia University to
carry out different measurements with a small LXe detector and behaved exactly
as predicted.
