Use of a ring detector in the technique of Rayleigh scattering of Moessbauer radiaiton

An installation for measuring Rayleigh scattering of Moessbauer radiation is described. The detector of the ring configuration collects radiation scattered at average <2 THETA > angle relatively to the symmetry axis that gives 20 time advantage in counting rate as compared with usual geometry. Laminated collimator made in the form of lead cylinder with cone hole is chosen for decrease of undesirable background radiation from secondary X-rays within 14.4 keV range. Inner working channels are made of copper and intermediate layer- of cadmium. Scintillation counter located behind the collimator comprises NaI(Tl) crystal made in the form of a ring with outside 62 and 28 mm internal diameters, 0.1 mm thickness and photomultiplier PEI-82. Application of the crystal in the form of a ring instead of disk permits to increase 1.5 times signal/bakground ratio. The average scattering angle is <2THETA>=12 deg, reception angle approximately 5 deg. A conclusion is made on good coincidence of measurement results exercised by means of the described installation with the data obtained in installation of general geometry