SOLAR NEUTRINOS AND STELLAR PROCESSES
Working group statement:
The fusion reactions in the Sun that
produce solar energy by nuclear reactions also provide a well-defined source
of low-energy neutrinos that can be used to study both the properties of neutrinos
and those of the Sun. For more than 30 years, measurements have indicated a
significant deficit of solar neutrinos compared to that predicted by standard
solar models with standard neutrino properties. This implied the exciting need
of new particle physics but conversely limited our capability of learning from
the Sun interior. Recently, the Sudbury Neutrino Observatory (SNO) has provided
model-independent evidence of the presence of this new particle physics: the
electron neutrinos produced in the Sun convert to muon and/or tau neutrinos
(or anti-neutrinos) in their way from the Sun's core to the Earth. Despite the
enormous impact of this result, many questions remain still unanswered:
- Are oscillations the flavor conversion mechanism?
- If so, what are the precise oscillation parameters?
- Do neutrinos have other properties, such as magnetic moments?
- The evidence for flavor conversion indicates that neutrino oscillations within a supernova can lead to substantial modifications of the evolution of the supernova and of the production of heavy elements. Do oscillations play an important role in supernova?
- Once the neutrino properties are precisely determined, what additional information can we learn about the interior of the Sun? ...
In summary, the recent results have transformed the field from asking the question: "Do solar neutrinos oscillate?" to one in which precision measurements are required to determine in detail the properties of neutrinos and to teach us about the interior of the stars.
The proposed National Underground Science Laboratory would provide new capabilities to address all these questions. New solar neutrino detectors are under development to study the full range of neutrinos produced by the Sun. In order to take advantage of the proposed new detectors, it is essential that we understand more precisely the nuclear processes that produce neutrinos in the stars. Progress has been made in the measurement of the relevant nuclear reaction cross sections by installing small accelerators deep underground, allowing one to measure very low reaction rates without the interference of cosmic ray backgrounds. NUSL would provide a site where more advanced accelerators and spectrometers could be installed to address the required nuclear cross section measurements.
The working group on solar neutrinos and stellar nuclear processes will focus on the reach of the new experiments being proposed for NUSL in this area. The parallel sessions will discuss the physics issues that solar and stellar neutrinos can address, the various approaches that new detectors are pursuing and the status of detector R&D, and the possibilities for improving our knowledge of nuclear cross sections relevant to neutrino production in the Sun and supernova. An important question that this working group will address is what the requirements are on NUSL in order to carry out the full scientific program that is possible with solar and stellar neutrinos.
The parallel sessions will consist
first of a set of overview talks that cover the physics that can be addressed
in studies of stellar neutrinos and the status of the experimental approaches
that are planned to carry out the physics program. Secondly, there will be a
series of talks that focus on specific physics issues and detector development
efforts, along with discussion of the possibilities for improved nuclear cross
section measurements. As many of the experimental efforts require the reduction
of radioactive backgrounds in the detectors to extremely low levels, the solar
neutrino part of this working group will work with the double beta decay, dark
matter, and national security working groups in a joint session.
Click Here to See the Solar Neutrinos & Stellar Processes Working Group Agenda