5 research outputs found
Constraints on millicharged particles with low threshold germanium detectors at Kuo-Sheng Reactor Neutrino Laboratory
Relativistic millicharged particles () have been proposed in various
extensions to the Standard Model of particle physics. We consider the scenarios
where they are produced at nuclear reactor core and via interactions of
cosmic-rays with the earth's atmosphere. Millicharged particles could also be
candidates for dark matter, and become relativistic through acceleration by
supernova explosion shock waves. The atomic ionization cross section of
with matter are derived with the equivalent photon approximation.
Smoking-gun signatures with significant enhancement in the differential cross
section are identified. New limits on the mass and charge of are
derived, using data taken with a point-contact germanium detector with 500g
mass functioning at an energy threshold of 300~eV at the Kuo-Sheng Reactor
Neutrino Laboratory.Comment: 8 pages, 7 figure
Status of global fits to neutrino oscillations
We review the present status of global analyses of neutrino oscillations,
taking into account the most recent neutrino data including the latest KamLAND
and K2K updates presented at Neutrino2004, as well as state-of-the-art solar
and atmospheric neutrino flux calculations. We give the two-neutrino solar +
KamLAND results, as well as two-neutrino atmospheric + K2K oscillation regions,
discussing in each case the robustness of the oscillation interpretation
against departures from the Standard Solar Model and the possible existence of
non-standard neutrino physics. Furthermore, we give the best fit values and
allowed ranges of the three-flavour oscillation parameters from the current
worlds' global neutrino data sample and discuss in detail the status of the
small parameters \alpha \equiv \Dms/\Dma as well as ,
which characterize the strength of CP violating effects in neutrino
oscillations. We also update the degree of rejection of four-neutrino
interpretations of the LSND anomaly in view of the most recent developments.Comment: v6: In the last Appendix we provide updated neutrino oscillation
results which take into account the relevant oscillation data released by the
MINOS and KamLAND collaboration
Characterization and performance of germanium detectors with sub-keV sensitivities for neutrino and dark matter experiments
Germanium ionization detectors with sensitivities as low as 100.eV(ee) (electron-equivalent energy) open new windows for studies on neutrino and dark matter physics. The relevant physics subjects are summarized. The detectors have to measure physics signals whose amplitude is comparable to that of pedestal electronic noise. To fully exploit this new detector technique, various experimental issues including quenching factors, energy reconstruction and calibration, signal triggering and selection as well as evaluation of their associated efficiencies have to be attended. The efforts and results of a research program to address these challenges are presented