•Generated by “weak” force
during p+® n
+ e+ + n
•“Massless” particles which
interact poorly with matter
–In that first respect, similar to
photons
–Can pass through sun without being
absorbed
–Same property makes them very hard to
detect
–
•Davis experiment at Homestake Mine in
Black Hills
–100,000 gallon tank of C2Cl4 dry cleaning fluid
–in Cl nuclei n + n ® p+ + e- so Cl (Z=17) becomes Ar (Z=18)
–Physically separate out the Ar, then wait
for it to radioactively decay
–Saw only 1/3 the neutrinos predicted