It is shown that the comparison of the results of the chlorine and lit
hium detectors can give valuable information for the solution of the s
olar neutrino problem. A brief description is presented of the prototy
pe of the lithium detector with 300 kg of metal lithium and of the pro
gress in the counting of Be-7 with high efficiency by a cryogenic mu-c
alorimeter. (C) 1997 Published by Elsevier Science B.V.