The use of 7Li isotope as a promising target for capturing solar neutrinos was first proposed by Zatsepin and Kuzmin and independently by Bahcall. Nuclei 7Li and 7Be are the mirror nuclei, and transitions between them are superallowed. Therefore, the cross section of the reaction

7Li + &nue &rarr 7Be + e-

is relatively large and can be calculated with high accuracy. Due to the thermal broadening of the energy spectrum of 7Be neutrinos, the detector has a certain sensitivity to beryllium neutrinos, as was first shown by Domogatsky and later was confirmed more accurately by Bahcall.


Other factors that make the detector very attractive are the small atomic weight of the target and a high (92.5%) abundance of 7Li in natural lithium. Taken together, these factors provide a small mass of a lithium target adequate for the detection of solar neutrinos of medium energy range (particulary CNO-neutrinos).


Ten tons of lithium suffice to construct a full-scale solar neutrino detector.A method for the detection of solar neutrino has been developed using the laboratory bench installations. The efficiency of the extraction of beryllium from lithium as high as 96.4% has been achieved, and it was shown that lithium losses during the extraction were less than 1%. The prospects of a full-scale experiment with a 10-t lithium detector consisting of twenty 500-kg lithium modules are discussed. The technical solutions formulated on the basis of this study enable to make design of a pilot lithium installation containing 500 kg of metallic lithium.


According to results of our calculations the 13N-neutrino flux is strong indicator of solar mixing so even very small mixing can be experimentally fixed (JCAP10(2008)007, JCAP08(2009)006). The variations of solar neutrino flux are shown on the pictures below in comparison with mean molecular weight.

F7 F15 F13

In case of mixing there will be some increase due to change of the 13N-neutrino flux. One can see on figure below the expected production rate for lithium with the corresponding uncertainties for the standard case and for the case with mixing when the flux F13 gets increase by 50%, 100%, 150% and 200% for HIGH Z and LOW Z models. One can see that lithium detector can discriminate these two models at 1&sigma level. If the measured production rate is in the region I, this will indicate the case of Low model without mixing. If it would be in region II, then we can only tell that this is the LOW Z model. The region III is compatible with LOW Z model with mixing. The region IV corresponds to case HIGH Z model and region V - to HIGH Z model with mixing. We don't know beforehand what region corresponds to a true value of the production rate. So the result of a lithium experiment is not fully predetermined by the results of previous experiments.