Oscillations of the $^7$Be solar neutrinos inside the Earth

TL;DR

This paper investigates the oscillations of solar $^7$Be neutrinos within the Earth, proposing methods to measure solar temperature, neutrino parameters, Earth's structure, and test fundamental physics with large-scale detectors.

Contribution

It provides a detailed analysis of $^7$Be neutrino oscillations in Earth's matter and suggests new ways to measure solar and Earth properties, as well as fundamental neutrino physics.

Findings

Oscillation depth is about 0.1-0.2% with a length of ~30 km.

Energy modulation period is comparable to the solar line width.

Future detectors could achieve precise measurements of solar and Earth properties.

Abstract

We explore in detail oscillations of the solar $^7$Be neutrinos in the matter of the Earth. The depth of oscillations is about $(0.1 - 0.2)\%$ and the length $\approx 30$ km. The period of the oscillatory modulations in the energy scale is comparable with the width of the line determined by the temperature in the center of the Sun. The latter means that depending on the length of trajectory (nadir angle) one obtains different degree of averaging of oscillations. Exploring these oscillations it is possible to measure the width of the $^7$Be line and therefore the temperature of the Sun, determine precisely $\Delta m^2_{21}$, perform tomography of the Earth, in particular, measure the deviation of its form from sphere, and detect small structures. Studies of the Be neutrinos open up a possibility to test quantum mechanics of neutrino oscillations and search for the sterile neutrinos. Accuracy of these measurements with future scintillator (or scintillator uploaded) detectors of the $\sim 100$ kton mass scale is estimated.