1,346 research outputs found
The MGDO software library for data analysis in Ge neutrinoless double-beta decay experiments
The GERDA and Majorana experiments will search for neutrinoless double-beta
decay of germanium-76 using isotopically enriched high-purity germanium
detectors. Although the experiments differ in conceptual design, they share
many aspects in common, and in particular will employ similar data analysis
techniques. The collaborations are jointly developing a C++ software library,
MGDO, which contains a set of data objects and interfaces to encapsulate, store
and manage physical quantities of interest, such as waveforms and high-purity
germanium detector geometries. These data objects define a common format for
persistent data, whether it is generated by Monte Carlo simulations or an
experimental apparatus, to reduce code duplication and to ease the exchange of
information between detector systems. MGDO also includes general-purpose
analysis tools that can be used for the processing of measured or simulated
digital signals. The MGDO design is based on the Object-Oriented programming
paradigm and is very flexible, allowing for easy extension and customization of
the components. The tools provided by the MGDO libraries are used by both GERDA
and Majorana.Comment: 4 pages, 1 figure, proceedings for TAUP201
Search for the Rare Decay K_{L}\to\pi^{0}\pi^{0}\gamma
The KTeV E799 experiment has conducted a search for the rare decay
via the topology
(where ). Due to Bose
statistics of the pair and the real nature of the photon, the
decay is restricted to proceed at lowest order
by the CP conserving direct emission (DE) of an E2 electric quadrupole photon.
The rate of this decay is interesting theoretically since chiral perturbation
theory predicts that this process vanishes at level . Therefore, this
mode probes chiral perturbation theory at . In this paper we report a
determination of an upper limit of (90% CL) for
. This is approximately a factor of 20 lower than
previous results.Comment: six pages and six figures in the submission. Reformatted for Physics
Review
Determination of the Parity of the Neutral Pion via the Four-Electron Decay
We present a new determination of the parity of the neutral pion via the
double Dalitz decay pi^0 -> e+ e- e+ e-. Our sample, which consists of 30511
candidate decays, was collected from K_L -> pi0 pi0 pi0 decays in flight at the
KTeV-E799 experiment at Fermi National Accelerator Laboratory. We confirm the
negative pi^0 parity, and place a limit on scalar contributions to the pi^0 ->
e+ e- e+ e- decay amplitude of less than 3.3% assuming CPT conservation. The
pi^0 gamma* gamma* form factor is well described by a momentum-dependent model
with a slope parameter fit to the final state phase space distribution.
Additionally, we have measured the branching ratio of this mode to be B(pi^0 ->
e+ e- e+ e-) = (3.26 +- 0.18) x 10^(-5).Comment: 5 pages, 4 figures. Typographical error in radiative branching ratio
(Eq. 6) correcte
Search for the Rare Decays KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-
The KTeV E799 experiment has conducted a search for the rare decays
KL->pi0pi0mu+mu- and KL->pi0pi0X0->pi0pi0mu+mu-, where the X0 is a possible new
neutral boson that was reported by the HyperCP experiment with a mass of (214.3
pm 0.5) MeV/c^{2}. We find no evidence for either decay. We obtain upper limits
of Br(KL->pi0pi0X0->pi0pi0mu+mu-) pi0pi0mu+mu-) <
9.2 x 10^{-11} at the 90% confidence level. This result rules out the
pseudoscalar X0 as an explanation of the HyperCP result under the scenario that
the \bar{d}sX0 coupling is completely real
Dispersive analysis of K_{L mu3} and K_{L e3} scalar and vector form factors using KTeV data
Using the published KTeV samples of K_L --> pi^{\pm} e^{\mp} nu and K_L -->
pi^{\pm} mu^{\mp} nu decays [1], we perform a reanalysis of the scalar and
vector form factors based on the dispersive parameterization [2,3]. We obtain
phase space integrals I^e_K = 0.15446 \pm 0.00025 and I^{mu}_K = 0.10219 \pm
0.00025. For the scalar form factor parameterization, the only free parameter
is the normalized form factor value at the Callan-Treiman point (C); our best
fit results in ln C = 0.1915 \pm 0.0122. We also study the sensitivity of C to
different parametrizations of the vector form factor. The results for the phase
space integrals and C are then used to make tests of the Standard Model.
Finally, we compare our results with lattice QCD calculations of F_K/F_pi and
f_+(0).Comment: 9 pages, 3 figures, to be published in PR
New result for the neutron -asymmetry parameter from UCNA
The neutron -decay asymmetry parameter defines the correlation
between the spin of the neutron and the momentum of the emitted electron, which
determines , the ratio of the axial-vector to
vector weak coupling constants. The UCNA Experiment, located at the Ultracold
Neutron facility at the Los Alamos Neutron Science Center, is the first to
measure such a correlation coefficient using ultracold neutrons (UCN).
Following improvements to the systematic uncertainties and increased
statistics, we report the new result which yields . Combination with the previous UCNA result and
accounting for correlated systematic uncertainties produces
and .Comment: 9 pages, 7 figures, updated to as-published versio
Search for neutron dark decay: n → χ + e⁺e⁻
In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. One of the possible final states discussed includes a single χ along with an e⁺e⁻ pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼ 4π acceptance using a pair of detectors that observe a volume of stored Ultracold Neutrons (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e⁻ + ν̅_e decays. The summed kinetic energy (E_(e⁺e⁻)) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel
The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76
The observation of neutrinoless double-beta decay would determine whether the
neutrino is a Majorana particle and provide information on the absolute scale
of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR,
an array of germanium detectors, to search for neutrinoless double-beta decay
of 76-Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be
enriched to 86% in 76-Ge. The DEMONSTRATOR will be deployed deep underground in
an ultra-low-background shielded environment. Operation of the DEMONSTRATOR
aims to determine whether a future tonne-scale germanium experiment can achieve
a background goal of one count per tonne-year in a 4-keV region of interest
around the 76-Ge neutrinoless double-beta decay Q-value of 2039 keV.Comment: Submitted to AIP Conference Proceedings, 19th Particles & Nuclei
International Conference (PANIC 2011), Massachusetts Institute of Technology,
Cambridge, MA, USA, July 24-29, 2011; 3 pages, 1 figur
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