HALO - The Helium and Lead Observatory

Supernova animation
Animation of Supernova Producing a Black Hole

This animation shows how a black hole may have formed in SN 1979C. The collapse of a massive star is shown, after it has exhausted its fuel. A flash of light from a shock breaking through the surface of the star is then shown, followed by a powerful supernova explosion. The view then zooms into the center of the explosion. CREDIT: NASA/CXC/A.Hobart

HALO, the Helium and Lead Observatory, is a carefully arranged detector composed of Helium-3 proportional counter tubes surrounded by lead. The density of lead increases the chance that a neutrino, an elusive particles emitted by nuclear phenomena, might interact with one of its atoms. This interaction generates neutrons, which are slowed and later captured by the Helium-3. The experiment is designed to detect the "blast wave" of neutrinos emitted by, for example, the collapse and explosion of a heavy, dying star in our galaxy. When such an event - a galactic supernova - occurs, even here on Earth this will prompt dozens of neutrons to be produced in less than one minute inside the HALO detector.


The neutrino blast wave can precede the light (illustrated in the animation at the right) by up to, or even more than, a day. This depends on the distance between the Earth and the supernova. Neutrinos provide an "early warning" that a supernova in our own galaxy may be about to become visible. Such an event can be bright enough to be seen during the daytime by the unaided eye. The last such occurrence of such a supernova was in the early 1600s, just before the invention of the telescope.

My current role is to support the experiment through monitoring shifts (3 days every couple of months), active work in the SNOLAB underground facility to calibrate and maintain the detector, and development and operation of data processing and validation software. This work is a partnership with my colleagues, at SNOLAB and internationally.

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