Degeneracy of de Broglie waves in geoneutrinos in the Earth's core

Journal of Astrophysics and Astronomy, 1983

Recent observations indicate that the primordial abundance of 4 He could be smaller than 0.24. It may then be necessary to invoke neutrino degeneracy in the early universe to explain the primordial abundances of helium and deuterium. It is shown here that the necessary degeneracy, though small, gives rise to a large asymmetry between the present number densities of neutrinos and antineutrinos. The effect of degeneracy on the upper limit to the neutrino masses is also considered.

2021

Anuj Kumar Upadhyay, 2, ∗ Anil Kumar, 3, 4, † Sanjib Kumar Agarwalla, 4, 5, ‡ and Amol Dighe § Department of Physics, Aligarh Muslim University, Aligarh 202002, India Institute of Physics, Sachivalaya Marg, Sainik School Post, Bhubaneswar 751005, India Applied Nuclear Physics Division, Saha Institute of Nuclear Physics, Bidhannagar, Kolkata 700064, India Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India International Centre for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India (Dated: December 30, 2021)

Physics Reports-review Section of Physics Letters, 2007

The deepest hole that has ever been dug is about 12 km deep. Geochemists analyze samples from the Earth's crust and from the top of the mantle. Seismology can reconstruct the density profile throughout all Earth, but not its composition. In this respect, our planet is mainly unexplored. Geo-neutrinos, the antineutrinos from the progenies of U, Th and 40 K decays in the Earth, bring to the surface information from the whole planet, concerning its content of natural radioactive elements. Their detection can shed light on the sources of the terrestrial heat flow, on the present composition, and on the origins of the Earth. Geo-neutrinos represent a new probe of our planet, which can be exploited as a consequence of two fundamental advances that occurred in the last few years: the development of extremely low background neutrino detectors and the progress on understanding neutrino propagation. We review the status and the prospects of the field.

Nuclear Physics B - Proceedings Supplements, 2005

The detection of neutrinos from U, Th, and K decay in the Earth (geo-neutrinos) will help to fix the total amount of long-lived radioactive elements and thus the radiogenic contribution to the terrestrial heat. Moreover, it will provide a direct test of a fundamental paradigm about the origin, formation and structure of the Earth, i.e., the Bulk Silicate Earth model. Alternative or variant models of Earth (including the presence of potassium or the possibility of a giant reactor in the core) can also be checked. This short review presents the status and prospects in this exciting field of research.

Advances in High Energy Physics, 2013

Geoneutrinos, electron antineutrinos from natural radioactive decays inside the Earth, bring to the surface unique information about our planet. The new techniques in neutrino detection opened a door into a completely new interdisciplinary field of neutrino geoscience. We give here a broad geological introduction highlighting the points where the geoneutrino measurements can give substantial new insights. The status-of-art of this field is overviewed, including a description of the latest experimental results from KamLAND and Borexino experiments and their first geological implications. We performed a new combined Borexino and KamLAND analysis in terms of the extraction of the mantle geo-neutrino signal and the limits on the Earth's radiogenic heat power. The perspectives and the future projects having geo-neutrinos among their scientific goals are also discussed.

Here we propose that there is a lot of heat producing elements U and Th in the Earth's outer core. The heat released from them may be the major energy source for driving the material movement within Earth's interior, including plate motion. According to seismic tomography, the hottest area is the mantle under the central Pacific Ocean. Combined with geomagnetic data, it is derived that the magnetic and heat convection centers deviate from Earth's geographic center to the Pacific direction for 400 km. Therefore, U and Th may be more concentrated in a position close to the equator in the lower outer core (from the middle to bottom of the outer core) under the central Pacific Ocean, and have formed a large U, Th-rich center there. Another small U, Thrich center may be located in a position close to the equator in the lower outer core under Africa, which is directly opposite of the large U, Th-rich center past the solid inner core. The two U, Thrich centers may have led to the formation of the Pacific and Africa super-plumes and are offering energy to run the plate tectonic system. The large U, Th-rich center also could have caused the temperature of the western hemisphere to be higher than that of the eastern hemisphere in the inner core, which may be the cause for the east-west hemispherical elastic anisotropy of the inner core. Periodical nuclear fissions of U and Th may have occurred in the outer core in Earth's geological history. This kind of natural fission of U and Th may be similar to the spontaneous fissions that occurred in Precambrian uranium mines. This is also supported by planetary quality and luminosity relation studies. Another piece of evidence comes from noble gases from volcanic rocks and their xenoliths in Pacific volcanic hot spots; since some of these noble gases could only be produced by nuclear fission of U and Th. Periodical U, Th fissions in the outer core might have triggered geomagnetic superchrons and reversals. At the same time, the energy released from the outer core during these events might have also triggered strong and extensive global geological and volcanic activities, and caused mass extinctions on the surface. It may have also led to Earth's cyclical expansions in its geological history.

2008

Two underground detectors, in Japan and Italy, are currently recording interactions of highly penetrating particles called geoneutrinos, which are naturally produced inside the Earth. By measuring the geoneutrino flux, these pioneering projects along with several other projects that are being planned are advancing constraints on the contribution of radioactive elements to Earth's heat budget in a novel way.

La Rivista del Nuovo Cimento, 2021

The review is conceived to provide a useful toolbox to understand present geoneutrino results with a view to shed light on Earth's energetics and composition. The status of the geoneutrino field is presented starting from the comprehension of their production, propagation, and detection, and going on with the experimental and technological features of the Borexino and KamLAND ongoing experiments. The current understanding of the energetical, geophysical and geochemical traits of our planet is examined in a critical analysis of the currently available models. By combining theoretical models and experimental results, the mantle geoneutrino signal extracted from the results of the two experiments demonstrates the effectiveness in investigating deep earth radioactivity through geoneutrinos from different sites. The obtained results are discussed and framed in the puzzle of the diverse classes of formulated Bulk Silicate Earth models, analyzing their implications on planetary heat budget and composition. As final remarks, we turn our gaze to the prospects in the field of geoneutrinos presenting the expectations of experiments envisaged for the next decade and the engaging technological challenges foreseen. Keywords KamLAND • Borexino • Antineutrinos detection • Radiogenic heat • Heat producing elements • Bulk silicate Earth List of symbols a(K) X Abundance of potassium in the reservoir X (ng g −1 or mg g −1) a(Th) X Abundance of uranium in the reservoir X (ng g −1 or mg g −1) B G. Bellini

Nature Geoscience, 2011

The total heat flow from the Earth s interior is 44.2 ± 1.0 TW from the analysis in ref. 1 of calorimetric-based data. On the other hand, a much lower value (31 ± 1 TW) is found in ref. 2. This analysis in ref. 2 has been severely criticized, see ref. 3 and 4. See also ref. 5. 2 Backgrounds to ν e detection The background to ν e detection arising from the α-particle-induced 13 C(α, n) 16 O reaction in the LS is particularly troublesome for the low energy geoneutrino region. The reaction produces neutrons with energies up to 7.3 MeV which subsequently thermalize via collisions with protons and carbon nuclei. ν e events are mimicked by neutron-induced recoils in the scintillator followed by neutron captures. In spite of the relatively large neutron energy, light quenching in the scintillator produces values for E p that are mainly below 3 MeV, as studied at intense neutron source facilities 6, 7. The principal source of α-particles is 210 Po, a daughter of 222 Rn introduced into the LS during the initial filling of the detector. The LS purification campaign in 2007 and 2008 reduced the 210 Po by a factor of ∼20. There are (5.95 ± 0.29) × 10 9 α-decays in the entire data set, as directly measured from the scintillation signal of the 5.3 MeV α-particle in the 210 Po decay. The

Earth and Planetary Science Letters, 2005

In preparation to the experimental results which will be available in the future, we study geo-neutrino production for different models of mantle convection and composition. By using global mass balance for the Bulk Silicate Earth, the predicted flux contribution from distant sources in the crust and in the mantle is fixed within a total uncertainty of ±15%. We also discuss regional effects, provided by subducting slabs or plumes near the detector. In four years a five-kton detector operating at a site relatively far from nuclear power plants can achieve measurements of the geo-neutrino signal accurate to within ±5%. It will provide a crucial test of the Bulk Silicate Earth and a direct estimate of the radiogenic contribution to terrestrial heat.

Nuclear and Particle Physics Proceedings, 2015

The Sun is fueled by a series of nuclear reactions that produce the energy that makes it shine. The primary reaction is the fusion of two protons into a deuteron, a positron and a neutrino. These neutrinos constitute the vast majority of neutrinos reaching Earth, providing us with key information about what goes on at the core of our star. Several experiments have now confirmed the observation of neutrino oscillations by detecting neutrinos from secondary nuclear processes in the Sun; this is the first direct spectral measurement of the neutrinos from the keystone proton-proton fusion. This observation is a crucial step towards the completion of the spectroscopy of pp-chain neutrinos, as well as further validation of the LMA-MSW model of neutrino oscillations.

2010

New measurements of the geo-neutrino flux are available from two independent and complementary experiments: Borexino and KamLAND. These new data decrease uncertainties on the flux and the derived radiogenic contribution to the terrestrial heat flow begins to be significant. The derived heat flow has a theoretical uncertainty from the accepted model of Earth. In the new future the range of the predictions should decrease mainly because of larger statistics collected by the two experiments and of a detailed geological study of the region near Borexino.

2012

Abstract. Recently the Borexino [1] and KamLAND [2] collaborations reported evidence of the geo-neutrino signal at more than 4 sigma. These experimental results constrain the contribution of radiogenic heat production in the Earth and provide a crucial test of the existing Bulk Silicate Earth (BSE) models. We developed a high resolution, geospatial reference model for the crust and lithospheric mantle in order to determine the U and Th concentration in the deep Earth from the geo-neutrino signal.