Speaker
Description
The last supernova near our galaxy was in 1987. HALO-1kT will be a low background galactic Supernova detector that uses 1kT of lead as the target for supernova neutrinos and helium-3 neutron counters to detect neutrons produced from the neutrino-lead interactions. The neutrons are then effectively captured by He-3 and converted to electrical signals by the proportional counters.
As with many experiments that want to detect particles coming from space, HALO- 1kT needs to have low ”backgrounds”. The term backgrounds refers to any ambient particles, or noise, which are unrelated to the supernova signal that the counters could pick up. Some backgrounds cannot be controlled, like the amount of neutrons in the lab at any given time, but there are backgrounds that can be minimized, like choosing the lowest background materials possible for building the counters. As HALO-1kT is planned to have 4.3 km of helium-3 counters, they need to have as low backgrounds as possible.
My research is testing the protype proportional counters to make sure their backgrounds are low enough to avoid regular false positives. The first way of testing them was to take the 4 counters underground at SNOLAB to collect 3-4 months of data as well as a 2-day calibration run to see what the base background rate is. After that two of counters were attached to electrostatic counters and counted for two months to determine the background of the wall material. Initial background rates show the prototype counters have 50x too much background. The ongoing research will help narrow down which part of the counters those backgrounds are coming from so that the materials used to make the actual counters will be cleaner allowing the counters to meet the background goals.
