ONLINE HE-CRYOSTAT FOR MOSSBAUER-SPECTROSCOPY WITH SHORT-LIVED RADIOACTIVE SOURCES

A special on-line He-cryostat for Mossbauer spectroscopy with accelera tor-produced radioactive sources was developed. The design of this cry ostat allows a computer-controlled irradiation of different targets an d the fast transport of these sources to the absorber. Therefore, this setup is suitable for Mossbauer spectroscopy even with very short-liv ed sources. The sources are cooled down to 15 K by a cryogenerator cap able of absorbing a beam power of 10 W in this temperature range. The liquid helium-cooled absorber is moved by a piezoelectric drive unit. Using this cryostat the sharp resonance of the Mossbauer effect in Ni- 63 was observed for the first time. In this experiment data from more than 1500 Co-63 sources (T1/2 = 27 s) have been collected.