Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268

Thu., September 30, 2004, at 3:00 p.m.

Measuring the Neutrino Luminosity of the Sun: The LENS-Sol Project

R. S. Raghavan, Virginia Tech
Building 6008 Conference Room

The luminosity of the sun as inferred from observing solar neutrinos at the earth (Lv), summarizes the detailed predictions of the standard solar model as well as the physics of neutrino flavor conversion that modifies the original fluxes in the travel to the earth. A precision measurement of Lv and its comparison with the photon luminosity of the sun L is thus the ultimate test of our knowledge of both. Despite the impressive recent advances in solar neutrino research the comparison Lv/L from measured fluxes and inferred neutrino physics is rather imprecise: Lv/L = 1.4+0.7-0.2 at 3sigma, allowing the possibility that Lv could be as large as 2.1 times L or 0.8 times L, both possibilities raising basic astrophysical questions. The remaining task in solar neutrino research is thus: measure Lv/L to a few percent by a direct measurement for the first time, of the complete low energy solar neutrino spectrum comprising the pp, 7Be, CNO fluxes that account for 99.7% of the solar neutrino output. Such a measurement would also provide for the first time, a physical test of LMA flavor conversion, improve the precision of the mixing angles sigma12 and sigma13, reveal the possible presence of subdominant basic physics scenarios such as non-standard interactions and sterile neutrinos as well as critically test CPT validity. The goal of LENS-Sol is observing the low energy solar neutrino spectrum in real time via tagged neutrino capture in 115In. The talk will cover recent technical progress in the development of this long awaited experiment for a precision test of the equality of the neutrino and photon luminosities of the sun.