749 research outputs found
Probing particle and nuclear physics models of neutrinoless double beta decay with different nuclei
Half-life estimates for neutrinoless double beta decay depend on particle
physics models for lepton flavor violation, as well as on nuclear physics
models for the structure and transitions of candidate nuclei. Different models
considered in the literature can be contrasted - via prospective data - with a
"standard" scenario characterized by light Majorana neutrino exchange and by
the quasiparticle random phase approximation, for which the theoretical
covariance matrix has been recently estimated. We show that, assuming future
half-life data in four promising nuclei (Ge-76, Se-82, Te-130, and Xe-136), the
standard scenario can be distinguished from a few nonstandard physics models,
while being compatible with alternative state-of-the-art nuclear calculations
(at 95% C.L.). Future signals in different nuclei may thus help to discriminate
at least some decay mechanisms, without being spoiled by current nuclear
uncertainties. Prospects for possible improvements are also discussed.Comment: Minor corrections in the text, references added. Matches published
version in Phys. Rev. D 80, 015024 (2009
An Impacting Descent Probe for Europa and the other Galilean Moons of Jupiter
We present a study of an impacting descent probe that increases the science
return of spacecraft orbiting or passing an atmosphere-less planetary body of
the solar system, such as the Galilean moons of Jupiter. The descent probe is a
carry-on small spacecraft (< 100 kg), to be deployed by the mother spacecraft,
that brings itself onto a collisional trajectory with the targeted planetary
body in a simple manner. A possible science payload includes instruments for
surface imaging, characterisation of the neutral exosphere, and magnetic field
and plasma measurement near the target body down to very low-altitudes (~1 km),
during the probe's fast (~km/s) descent to the surface until impact. The
science goals and the concept of operation are discussed with particular
reference to Europa, including options for flying through water plumes and
after-impact retrieval of very-low altitude science data. All in all, it is
demonstrated how the descent probe has the potential to provide a high science
return to a mission at a low extra level of complexity, engineering effort, and
risk. This study builds upon earlier studies for a Callisto Descent Probe (CDP)
for the former Europa-Jupiter System Mission (EJSM) of ESA and NASA, and
extends them with a detailed assessment of a descent probe designed to be an
additional science payload for the NASA Europa Mission.Comment: 34 pages, 11 figure
Magnetic Fluctuations and Turbulence in the Venus Magnetosheath and Wake
Recent research has shown that distinct physical regions in the Venusian
induced magnetosphere are recognizable from the variations of strength and of
wave/fluctuation activity of the magnetic field. In this paper the statistical
properties of magnetic fluctuations are investigated in the Venusian
magnetosheath, terminator, and wake regions. The latter two regions were not
visited by previous missions. We found 1/f fluctuations in the magnetosheath,
large-scale structures near the terminator and more developed turbulence
further downstream in the wake. Location independent short-tailed non-Gaussian
statistics was observed.Comment: 16 pages, 4 figure
Measurement of double beta decay of 100Mo to excited states in the NEMO 3 experiment
The double beta decay of 100Mo to the 0^+_1 and 2^+_1 excited states of 100Ru
is studied using the NEMO 3 data. After the analysis of 8024 h of data the
half-life for the two-neutrino double beta decay of 100Mo to the excited 0^+_1
state is measured to be T^(2nu)_1/2 = [5.7^{+1.3}_{-0.9}(stat)+/-0.8(syst)]x
10^20 y. The signal-to-background ratio is equal to 3. Information about energy
and angular distributions of emitted electrons is also obtained. No evidence
for neutrinoless double beta decay to the excited 0^+_1 state has been found.
The corresponding half-life limit is T^(0nu)_1/2(0^+ --> 0^+_1) > 8.9 x 10^22 y
(at 90% C.L.).
The search for the double beta decay to the 2^+_1 excited state has allowed
the determination of limits on the half-life for the two neutrino mode
T^(2nu)_1/2(0^+ --> 2^+_1) > 1.1 x 10^21 y (at 90% C.L.) and for the
neutrinoless mode T^(0nu)_1/2(0^+ --> 2^+_1) > 1.6 x 10^23 y (at 90% C.L.).Comment: 23 pages, 7 figures, 4 tables, submitted to Nucl. Phy
Searches for neutrinoless double beta decay
Neutrinoless double beta decay is a lepton number violating process whose
observation would also establish that neutrinos are their own anti-particles.
There are many experimental efforts with a variety of techniques. Some (EXO,
Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has
reported the first measurement of the half life for the double beta decay with
two neutrinos of Xe. The sensitivities of the different proposals are
reviewed.Comment: 8 pages, prepared for TAUP 201
Searches for neutrinoless double beta decay
Neutrinoless double beta decay is a lepton number violating process whose
observation would also establish that neutrinos are their own anti-particles.
There are many experimental efforts with a variety of techniques. Some (EXO,
Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has
reported the first measurement of the half life for the double beta decay with
two neutrinos of Xe. The sensitivities of the different proposals are
reviewed.Comment: 8 pages, prepared for TAUP 201
Searches for neutrinoless double beta decay
Neutrinoless double beta decay is a lepton number violating process whose
observation would also establish that neutrinos are their own anti-particles.
There are many experimental efforts with a variety of techniques. Some (EXO,
Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has
reported the first measurement of the half life for the double beta decay with
two neutrinos of Xe. The sensitivities of the different proposals are
reviewed.Comment: 8 pages, prepared for TAUP 201
Observables sensitive to absolute neutrino masses: A reappraisal after WMAP-3y and first MINOS results
In the light of recent neutrino oscillation and non-oscillation data, we
revisit the phenomenological constraints applicable to three observables
sensitive to absolute neutrino masses: The effective neutrino mass in single
beta decay (m_beta); the effective Majorana neutrino mass in neutrinoless
double beta decay (m_2beta); and the sum of neutrino masses in cosmology
(Sigma). In particular, we include the constraints coming from the first Main
Injector Neutrino Oscillation Search (MINOS) data and from the Wilkinson
Microwave Anisotropy Probe (WMAP) three-year (3y) data, as well as other
relevant cosmological data and priors. We find that the largest neutrino
squared mass difference is determined with a 15% accuracy (at 2-sigma) after
adding MINOS to world data. We also find upper bounds on the sum of neutrino
masses Sigma ranging from ~2 eV (WMAP-3y data only) to ~0.2 eV (all
cosmological data) at 2-sigma, in agreement with previous studies. In addition,
we discuss the connection of such bounds with those placed on the matter power
spectrum normalization parameter sigma_8. We show how the partial degeneracy
between Sigma and sigma_8 in WMAP-3y data is broken by adding further
cosmological data, and how the overall preference of such data for relatively
high values of sigma_8 pushes the upper bound of Sigma in the sub-eV range.
Finally, for various combination of data sets, we revisit the (in)compatibility
between current Sigma and m_2beta constraints (and claims), and derive
quantitative predictions for future single and double beta decay experiments.Comment: 18 pages, including 7 figure
Double beta decay: present status
The present status of double beta decay experiments (including the search for
, EC and ECEC processes) are reviewed. The results of
the most sensitive experiments are discussed. Average and recommended half-life
values for two-neutrino double beta decay are presented. Conservative upper
limits on effective Majorana neutrino mass and the coupling constant of the
Majoron to the neutrino are established as eV and , respectively. Proposals for future double beta decay
experiments with a sensitivity for the at the level of (0.01-0.1)
eV are considered.Comment: 33 pages included 7 figures and 14 tables; an extended version of the
invited talk at 13th Lomonosov Conference of Elementary Particle Physics,
23-29 August, 2007, Moscow, Russi
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