Reactor as a Source of Antineutrinos: Thermal Fission Energy

Deeper insight into the features of a reactor as a source of antineutrinos is required for making further advances in studying the fundamental properties of the neutrino. The relationship between the thermal power of a reactor and the rate of the chain fission reaction in its core is analyzed.Comment: 15 pages in LaTex and 4 ps figure

Testing whether muon neutrino flavor mixing is maximal

The small difference between the survival probabilities of muon neutrino and antineutrino beams, traveling through earth matter in a long baseline experiment such as MINOS, is shown to be an important measure of any possible deviation from maximality in the flavor mixing of those states.Comment: Some revision has been made in the experimental discussions with two new figures replacing the old ones and a clarification of the accuracy of the perturbative result has been included. This version will be published in Physical Review Letters. Title changed as asked by the editors of Physical Review Letter

Implications of a Massless Neutralino for Neutrino Physics

We consider the phenomenological implications of a soft SUSY breaking term BN at the TeV scale (here B is the U(1)_Y gaugino and N is the right-handed neutrino field). In models with a massless (or nearly massless) neutralino, such a term will give rise through the see-saw mechanism to new contributions to the mass matrix of the light neutrinos. We treat the massless neutralino as an (almost) sterile neutrino and find that its mass depends on the square of the soft SUSY breaking scale, with interesting consequences for neutrino physics. We also show that, although it requires fine-tuning, a massless neutralino in the MSSM or NMSSM is not experimentally excluded. The implications of this scenario for neutrino physics are discussed.Comment: 14 pages, latex, no figure

Majorana neutrinos, neutrino mass spectrum, CP-violation and neutrinoless double beta-decay. I : The three-neutrino mixing case.

Assuming three-neutrino mixing and massive Majorana neutrinos, we study the implications of the neutrino oscillation solutions of the solar and atmospheric neutrino problems and of the results of the CHOOZ experiment for the predictions of the effective Majorana mass in neutrinoless double-beta [(ββ)0ν] decay, |〈m〉|. The general case of CP nonconservation is investigated. The predicted values of |〈m〉|, which determine the magnitude of the (ββ)0ν-decay rate, depend strongly on the type of neutrino mass spectrum and on the solution of the solar neutrino problem, as well as on the values of the two Majorana CP-violating phases, present in the lepton mixing matrix. We find that (i) |〈m〉|≲0.02 eV for a hierarchical neutrino mass spectrum, (ii) |〈m〉|≲0.09 eV if the spectrum is of the inverted hierarchy type, and (iii) |〈m〉|0 being the common neutrino mass scale which is limited by the bounds from the 3H β-decay experiments, m<2.5 eV. The indicated maximal values of |〈m〉| are reached in cases (i), (ii), and (iii), respectively, for the large mixing angle (LMA) MSW solution, the small mixing angle (SMA) MSW solution, and for all current solutions of the solar neutrino problem. If CP invariance holds, |〈m〉| is very sensitive to the values of the relative CP parities of the massive Majorana neutrinos. The cases of neutrino mass spectra which interpolate between the hierarchical or inverted hierarchy type and the quasidegenerate one are also studied. The observation of the (ββ)0ν decay with a rate corresponding to |〈m〉|≳0.02 eV can provide unique information on the neutrino mass spectrum. Combined with information on the lightest neutrino mass or the type of neutrino mass spectrum, it can give also information on the CP violation in the lepton sector and, if CP invariance holds, on the relative CP parities of the massive Majorana neutrinos

Optical telescopes for COMPASS RICH1 up-grade

The central photon detection area of the Ring Imaging Cherenkov detector at COMPASS, a particle physics experiment at CERN SPS dedicated to hadron physics, has been upgraded from the previous system formed by wire chambers with CsI layers to a very fast UV extended multi anode photo multiplier tube array (MAPMT), including 576 tubes. The active area covered by the MAPMTs is 7.3 times smaller than the one previously equipped with CsI photocathodes, so 576 optical concentrators transforming the image from the old system focal plane to the new photocathode plane were needed. The telescope system formed by two fused silica lenses was designed, produced and assembled. The first prismatic plano-convex field lens is placed in the focal plane of the RICH mirrors. The second condenser lens is off centered and tilted and has one aspherical surface. All lenses have antireflection coating