May 19 – 23, 2019
Europe/Madrid timezone

Reduction of Cosmogenic Radioactivity in Low Background Detectors

Not scheduled


Dr Frank T. Avignone III


The elimination of radio isotopes generated by high-energy cosmic-ray neutrons from
detector materials is critically important to achieve the maximum sensitivity in, for
example, dark matter, double-beta decay, and axion searches. A clear demonstration of
such a reduction was observed in the low-energy spectrum from the MAJORANA
DEMONSTRATOR (MJD). In particular, the beta spectrum from cosmogenic tritium, usually
observed in germanium detectors, was reduced by a factor of 20 in the MJD spectrum.
This was achieved by zone refining the input Ge, and by re-zone refining scrap Ge at
each step, and by storing all material underground whenever it was not being used in
production. The facility used by MJD, and its operation, were very costly and required
significant space and infrastructure. A novel method is under development, which if
successful, could purify Ge, TeO2, and possibly LiMoO4, all materials that are being used
in low background experiments. The entire facility is compact, and could be operated
underground. A description of the facility and techniques, as well as a progress report,
will be given.

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