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Internal Radioactive Source Calibration of the
Borexino Solar Neutrino Experiment
Henning Olling Back
(Abstract)
A measurement of solar neutrinos below 1 MeV of energy will further our
knowledge of the neutrino’s mass and mixing properties and will provide a probe to
possible physics beyond the standard model of particle physics, as well as advance our
understanding of energy production in the Sun.
Borexino is a liquid scintillator detector that will measure the neutrino energy
spectrum to the lowest energy threshold to date. It has been designed to measure the flux
of the mono-energetic neutrinos produced by electron capture on 7Be in the Sun’s core,
which will produce a Compton-like edge in the energy spectrum. Because of the low
count rate, Borexino requires extremely low backgrounds, and a good understanding of
the backgrounds that do exist.
Although the purification techniques used for the
scintillator lowered the radioactive contaminates to levels never before achieved, cuts
must still be made to the data.
At Virginia Tech, we have developed an internal source calibration program that
will be able to give us a thorough understanding of both the pulse shape discrimination
efficiency and the energy and time response of Borexino. Energy calibration for alphas,
betas, and gammas (energy scales) can be accomplished with such sources. When the
calibration source is used in conjunction with an accurate source location system any
spatial dependencies can be found. The system will use different types of sources at
various energies to give the required information to make the cuts needed to extract
believable physics from the detector.