Spectroscopy of Solar Neutrinos

In the last years, liquid-scintillator detectors have opened a new window for the observation of low-energetic astrophysical neutrino sources. In 2007, the solar neutrino experiment Borexino began its data-taking in the Gran Sasso underground laboratory. High energy resolution and excellent radioactive background conditions in the detector allow the first-time spectroscopic measurement of solar neutrinos in the sub-MeV energy regime. The experimental results of the Beryllium-7 neutrino flux measurements as well as the prospects for the detection of solar Boron-8, pep and CNO neutrinos are presented in the context of the currently discussed ambiguities in solar metallicity. In addition, the potential of the future SNO+ and LENA experiments for high-precision solar neutrino spectroscopy will be outlined.Comment: 6 pages, 5 figures, highlight talk at the annual fall meeting of the German Astronomische Gesellschaft in Potsdam (Sep 2009

Solar-neutrino physics with Borexino

The Borexino solar-neutrino detector is a high-radiopurity lowthreshold liquid scintillator that detects solar neutrinos by means of the elastic scattering νe → νe reaction. The detector, located at the Laboratori Nazionali del Gran Sasso (LNGS, Italy) and has now measured solar neutrinos from the 7Be, 8B and pep components. Terrestrial neutrinos (geoneutrinos) have also been observed

Electromagnetic properties of neutrinos

A short review on electromagnetic properties of neutrinos is presented. In spite of many efforts in the theoretical and experimental studies of neutrino electromagnetic properties, they still remain one of the main puzzles related to neutrinos.Comment: The talk presented by A.Studenikin at the International Conference on Topics in Astroparticle and Underground Physics, Rome (Italy), July 1-5, 200

New bounds on neutrino magnetic moment and re-examination of plasma effect in neutrino spin light

Recent discussion on the possibility to obtain more stringent bounds on neutrino magnetic moment has stimulated new interest to possible effects induced by neutrino magnetic moment. In particular, in this note after a short review on neutrino magnetic moment we re-examine the effect of plasmon mass on neutrino spin light radiation in dense matter. We track the entry of the plasmon mass quantity in process characteristics and found out that the most substantial role it plays is the formation of the process threshold. It is shown that far from this point the plasmon mass can be omitted in all the corresponding physical quantities and one can rely on the results of massless photon spin light radiation theory in matter.Comment: to appear in Nuovo Cimento 35 C, No. 1, 2012 (based on the talk presented at the 25th Rencontres de Physique de la Vallee d'Aoste on "Results and Perspectives in Particle Physics", La Thuile, February 27 - March 5, 201

Real-time spectroscopy of solar pp neutrinos using Nd-150

The potential real-time spectroscopy of solar pp neutrinos using Nd-150 as target is investigated. The threshold of 196 keV would be the lowest of all solar neutrino experiments running so far. Experimental rates and parameters are discussed, about 580 SNU can be expected from pp-neutrinos and another 367 SNU from Be-7. Furthermore, it is investigated whether charged current reactions might cause a new background component for future double beta decay experiments based on a large amount of Nd-150.Comment: 9 pages, 1 figur

Looking at the Sun’s core. CNO and pep solar neutrino detection in Borexino

Both the first evidences and the first discoveries of neutrino flavor transformation have come from experiments which detected neutrinos from the Sun. Observation of solar neutrinos directly addresses the theory of stellar structure and evolution, which is the basis of the standard solar models (SSMs). The Sun as a well-defined neutrino source also provides extremely important opportunities to investigate nontrivial neutrino properties such as neutrino oscillations and Mikheyev-Smirnov-Wolfenstein (MSW) effect, because of the wide range of matter density and the great distance from the Sun to the Earth. The ultra-pure Borexino detector at Laboratori Nazionali del Gran Sasso is designed to perform low-energy solar neutrino spectroscopy. Recently, the Borexino experiment has obtained the first direct evidence of the rare proton-electron-proton (pep) fusion reaction in the Sun by the detection of the neutrinos emitted in the process. Borexino has also placed the strongest limit on the flux of the neutrinos emitted in the carbon-nitrogen-oxygen (CNO) cycle. In these proceedings I will summarise the novel techniques adopted in Borexino to reduce the cosmogenic and external background contributions and I will describe the physics results obtained

Nuclear electron capture rate in stellar interiors and the case of 7Be

Nuclear electron capture rate from continuum in an astrophysical plasma environment (like solar core) is calculated using a modified Debye-Huckel screening potential and the related non-Gaussian q-distribution of electron momenta. For q=1 the well-known Debye-Huckel results are recovered. The value of q can be derived from the fluctuation of number of particles and temperature inside the Debye sphere. For 7Be continuum electron capture in solar core, we find an increase of 7 -- 10 percent over the rate calculated with standard Debye-Huckel potential. The consequence of this results is a reduction of the same percentage of the SSM 8B solar neutrino flux, leaving unchanged the SSM 7Be flux.Comment: 8 pages, 1 figure, IOP macro style, submitted to JP