Neutrino Helioseismology

The observed deficit of B solar neutrinos may call for an improved standard model of the sun or an expanded standard model of particle physics (e.g., with neutrino masses and mixing). In the former case, contemporary fluid motions and thermal fluctuations in the sun’s core may modify nuclear reaction rates and restore agreement. To test this notion, we propose a search for short–term variations of the solar neutrino flux. CERN-TH 6608/92, HUTP-92/A038 The observed deficit of B solar neutrinos [1]–[4] may call for an improved standard model of the sun or an expanded standard model of particle physics (e.g., with neutrino masses and mixing). In the former case, contemporary fluid motions and thermal fluctuations in the sun’s core may modify nuclear reaction rates and restore agreement [5] [6]. To test this notion, we propose a search for short–term variations of the solar neutrino flux. Models of the sun fit its radius R ⊙ and luminosity L ⊙ to an assumed initial He abundance and a convective mixing length [7]–[10]. While challenged by solar–neutrino observations, they are supported by solar-surface measurements [11] of the frequencies of thousands of p–waves (pressure waves). These are inverted to yield the sound velocity at depth [12] [13]. Whilst the result agrees with solar models to better than 1%, helioseismology provides scant information about the solar core, where p waves are damped [14]. Solar g waves (for which gravity is the restoring force) are suppressed toward the surface and difficult to see, but they may well be present. As the sun evolves, the He abundance in its core develops a positive outward gradient. This leads [15] [16] to a hydrostatic instability (often ignored in standard solar models) and to the secular growth of radially asymmetric standing g waves of low order n (number of radial nodes) and degree l (multipole moment). Their periods (2π/ω) are of order one hour [14] [17]. Since energy–tranport times are much larger, g waves correspond to quasi–adiabatic temperature fluctuations about a radial mean: T (r, t, θ, φ) = T (r) [ 1 + Ag(r)Ylm(θ, φ) √ 2 cos(ωt) ]