The HALO detector is now in operation, since May 8, 2012.

The announcement from Clarence Virtue:

We are happy to share with you that, just in time for the grand opening of
SNOLAB, the Helium and Lead Observatory for Supernova Neutrinos (HALO) is
up and running. The concept of HALO dates back to 1996 when Cliff Hargrove
proposed the Lead Astronomical Neutrino Detector (LAND) as a long lifetime
supernova detector. In 2004 Charles Duba renamed the nascent detector to
HALO when we decided to use the 3He proportional counters from the SNO
experiment. The design and construction of HALO started in 2007.

The purpose of HALO is to observe the neutrinos from the next galactic
supernova. These particles stream out before the photons do, giving us an
opportunity to alert astronomers through the Supernova Early Warning
System (SNEWS) so that the light signal can be caught in real-time. Just
like we were able to look into the Sun with the SNO detector, HALO and
other supernova detectors, will give us a window into the mechanics of the
supernova explosion.

Although we still have much work to do to fully calibrate the detector, we
have all of the 128 proportional counters connected to 64 data acquisition
channels.

Supernova, we’re ready for you!