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Single
Crystal Molybdates for Neutrinoless Double Beta Decay Experiments—Integrated
Photonics, Inc.,
Dr. Irina
Mnushkina,
Dr. Vincent J.
Fratello, Business Official, vjfratello@integratedphotonics.com
DOE Grant No.
DE-FG02-04ER83983
Amount: $700,000
The Neutrinoless Double Beta Decay
Underground Detector has been identified by the DOE as a high scientific
priority for Nuclear Physics research; however, the current generation of
proposed experiments to determine neutrino mass would require 500 kg of
germanium (Ge), which would cost more than $100 million. Therefore, several alternate parent isotopes
for neutrinoless double beta decay have been suggested as candidates. The 100Mo isotope of molybdenum is
particularly promising because it has large decay energy, resulting in a signal
above gamma ray backgrounds. The nuclear
structure of this relatively light nuclide has been shown to be simple enough
to allow reliable calculation of the parameters needed to extract the effective
neutrino mass from the measured half-life.
However, these advantages can only be exploited if a detector can be constructed
with both high detection efficiency and excellent energy resolution. The only known method is to construct a
bolometer of a single crystal from a compound that contains a significant
fraction of molybdenum. Therefore, this
project will develop technology for the bulk crystal growth of single crystal
molybdate (a molybdenum oxide compound), so that large crystals can be
routinely and cost-effectively grown. In Phase I,
three molybdate compositions were investigated to determine: (1) their growability by the Czochralski
method of bulk crystal growth; and (2) their potential use as cryogenic
bolometer materials without any energy interferences, radiation effects, or
other problems. One of the three
materials was selected as a target composition, and independent bolometer tests
indicated that the target composition would be an excellent host for 100Mo
in bolometer applications. In Phase II,
the target molybdate compound will be optimized for crystal growth and
fabrication of cubes for bolometer applications. A large crystal enriched with 100Mo
will be grown and fabricated for complete bolometer testing.
Commercial Applications And Other Benefits as described by the awardee: The dominant application of the single
crystal molybdates would be for cryogenic bolometers for neutrinoless double
beta decay. Because the target molybdate
compound is a good low-temperature scintillator, with luminescence arising from
the molybdenum oxide complexes, secondary commercial applications are antici