A SETUP FOR DETECTION OF MOSSBAUER SELF-ABSORPTION OF GAMMA-QUANTA OFA AG-109M LONG-LIVED ISOMER

The setup is designed for searching for Mossbauer self-absorption of 8 8-keV gamma-quanta from Ag-109m in a single-crystal source-absorber by comparing the temperature dependences of gamma-quanta yields int he h orizontal and vertical directions. If the gamma-resonance broadening i s small, then the gravitational red shift restricts the effective reso nant absorption length in the vertical gamma-ray beam. The setup inclu des a small-sized cryostat, two Ge(Li) detectors, and a system compens ating for the vertical component of the Earth's magnetic field. By per iodically switching this system on and off, one may observe a synchron ous modulation of the resonant absorption probability in the horizonta l direction. The expected decrease in the gamma-ray intensity int he h orizontal beam as a results of the Mossbauer effect is similar to 5 x 10(-4) for a gamma-source cooled from 77 to 4.2 K. For the vertical be am, such as decrease is similar to 7 times smaller.