Abstract After analysing results on the measurement of the acceleration of gravity using a physical pendulum in our teaching laboratory, we found that the value reported by the students is always higher than the theoretical expectations. In this article we analyze critically some of the students hypotheses for such displacement, and we perform an investigation of our own to detect what is leading to this result. We disregarded any flaw on the experimental procedure performed by the students, and instead, concluded that the miscalibration of the laboratory instruments was distorting the students measurements, leading to a ~ 5 % increase in the calculated value of the acceleration of gravity.

There are reasons to believe that the solar matter density fluctuates around an equilibrium profile. One of these reasons is a resonance between the Alfvén waves and the g-modes inside the Sun that creates spikes in the density profile. The neutrinos are created in the solar core and passing through these spikes feel them as a noisy perturbation, whose correlation length is given by the distance between the spikes. When we consider these perturbations on the density profile, the values of the neutrino parameters necessary to obtain a solution to the solar neutrino problem are affected. In particular, in the present work, we show that the values of the parameters of mass and mixing angle that satisfy both the Large Mixing Angle solution to the solar neutrinos and the data from KamLAND - that observes neutrinos created in earth nuclear reactors - are shifted in the direction of lower values as the amplitude of the density noise increases. This means that, depending on the new data of KamLAND and other detectors, it can be necessary to invoke random perturbations in the Sun to recover compatibility with solar neutrino observations. In this case, the neutrino observations will be used as a real probe of the solar interior, giving information of the density profile in the central part of the Sun, which can not be observed directly.

The first KamLAND results are in a very good agreement with the predictions made on the basis of the solar neutrino data and the LMA realization of the MSW mechanism. We perform a combined analysis of the KamLAND (rate, spectrum) and the solar neutrino data with a free boron neutrino flux fB. The best fit values of neutrino parameters are deltam² = 7.1.10-5 eV², tan² theta = 0.40 and fB = 1.04 with the 1sigma intervals: deltam² = (6.4 - 8.4). 10-5 eV², tan² theta = 0.33 - 0.48. We find the 3sigma upper bounds: deltam² < 1.7 . 10-4 eV² and tan² theta< 0.64, and the lower bound deltam² > 4.8 . 10-5 eV². In the best fit point we predict for SNO: CC/NC = <IMG SRC="/img/revistas/bjp/v34n4a/a19img01.gif">and <IMG SRC="/img/revistas/bjp/v34n4a/a19img02.gif" > or = 3.0 ± 0.8% (68% C.L.), and <IMG SRC="/img/revistas/bjp/v34n4a/a19img02.gif">< 6% at the 3sigma level. Further improvements in the determination of the oscillation parameters are discussed and implications of the solar neutrino and KamLAND results are considered.