Frozen spin solid targets developed at JINR Dubna

Experience with polarized targets and the achievement of very low temperatures at the Laboratory of Nuclear Problems (JINR, Dubna) and at other places have triggered the idea of using a radically new technique based on dissolving 3He in 4He to create a frozen spin polarized target. The short history of the development of such proton and deuteron targets at the LNP is given. Diols with the complex Cr(V) are used as target materials. A characteristic feature of these targets is the long relaxation time (≈1000 h) in magnetic fields of about 0.5 T. Lately, the Saclay–Argonne frozen spin polarized proton target used initially in the E704 experiment at FERMILAB has been upgraded by adding the missing parts. A first physics experiment has been carried out.