The Helium and Lead Observatory (HALO) is a dedicated supernova neutrino detector that is presently under construction underground at SNOLAB in the Creighton Mine in Sudbury Ontario Canada.
It uses 76 tonnes of annular lead blocks instrumented with 128 tubular Helium-3 neutron detectors to detect neutrinos from supernovae within our galaxy. As a part of the worldwide Supernova Early Warning System (SNEWS), it will help detect supernovae by their neutrino burst, before their light reaches Earth, allowing time to notify both professional and amateur astronomers.
World Wide, several detectors currently running or nearing completion are sensitive to a core collapse supernova neutrino signal in the Milky Way. The neutrino signal emerges promptly from a supernova’s core, whereas it may take hours for the first photons to be visible. Therefore, the detection of the neutrino burst from the next Galactic supernova can provide an early warning for astronomers. Putting several detectors in coincidence can provide the astronomical community with a very high confidence early warning of the supernova’s occurrence. In addition, the SNEWS alarm may be able to serve as a trigger for detectors which are not able to trigger on a supernova signal by themselves, allowing extra data to be saved.
The SNEWS project involves an international collaboration of experimenters representing current supernova neutrino detectors. In addition, gravitational wave detectors will be involved. The goal of SNEWS is to provide the astronomical community with a prompt alert of the occurrence of a Galactic core collapse event. We are also engaged in cooperative inter-experiment work, such as downtime coordination and inter-experiment timing verification, designed to optimize global sensitivity to a core collapse supernova signal.