Gallax and Sage experiments

These were new experiments that can ``see'' all of the expected solar neutrinos. SAGE is in Russia, GALLAX is in Italy. Both are underground. GALLAX is in an underground laboratory next to a highway tunnel, as indicated on the map:

The experiments are based on

⁷¹Ga + neutrino --> ⁷¹Ge + electron.

(Gallium, Ga has 31 protons while germanium, Ge has 32 protons. Thus one proton got converted into a neutron.)

Conceptually, these experiments are similar to the chlorine experiment. A few atoms of gallium are changed into germanium. The germanium atoms are extracted and then the experiment looks for the decay of the germanium (Ge) atoms, as indicated in the following picture (courtesy of the GALLAX experiment)

The important difference between these experiments and the initial chlorine experiment is that these are sensitive to the lower energy neutrinos that come from the main energy producing reaction in the sun. The prediction for how many of these neutrinos are made should be very accurate since we know the rate at which the sun makes energy.

Result: Neutrino reactions detected, but not as many as expected based on the theoretical calculations.

Here is a link to the Gran Sasso Laboratory in Italy, where the GALLEX experiment. Information about the GALLEX experiment can be found here.

ASTR 122 course home page

Updated 22 Octobber 2007

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA