  The isomer 83mKr with its half-life of 1.83 h is an ideal calibration source
for a liquid noble gas dark matter experiment like the XENON project. However,
the risk of contamination of the detector with traces of the much longer lived
mother isotop 83Rb (86.2 d half-life) has to be ruled out. In this work the
release of 83Rb atoms from a 1.8 MBq 83Rb source embedded in zeolite beads has
been investigated. To do so, a cryogenic trap has been connected to the source
for about 10 days, after which it was removed and probed for the strongest 83Rb
gamma-rays with an ultra-sensitive Germanium detector. No signal has been
found. The corresponding upper limit on the released 83Rb activity means that
the investigated type of source can be used in the XENON project and similar
low-background experiments as 83mKr generator without a significant risk of
contaminating the detector. The measurements also allow to set upper limits on
the possible release of the isotopes 84Rb and 86Rb, traces of which were
created alongside the production of 83Rb at the Rez cyclotron.
