Thule Neutron Monitor
Thule neutron monitor, oldest of the monitors operated
by Bartol Research Institute, began collecting data in 1957.
The neutron detector tubes are inside the four white boxes
encased in polyethylene. The three smaller boxes at left
each contain three detector tubes of the traditional "BP28"
design, which uses boron trifluoride to capture neutrons.
The larger box at right was added in 2001. It contains
nine tubes of a newer design that uses helium-3 to capture
neutrons. Photo by J Roth, 2001.
Building 561 on Thule Air Force Base, Greenland,
home of the Thule neutron monitor since August 20, 1997.
Photo by L Shulman, 1999.