White Paper: Measuring the Neutrino Mass Hierarchy

This white paper is a condensation of a report by a committee appointed jointly by the Nuclear Science and Physics Divisions at Lawrence Berkeley National Laboratory (LBNL). The goal of this study was to identify the most promising technique(s) for resolving the neutrino mass hierarchy. For the most part, we have relied on calculations and simulations presented by the proponents of the various experiments. We have included evaluations of the opportunities and challenges for these experiments based on what is available already in the literature.Comment: White paper prepared for Snowmass-201

Radon mitigation during the installation of the CUORE 0νββ0\nu\beta\beta decay detector

CUORE - the Cryogenic Underground Observatory for Rare Events - is an experiment searching for the neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{130}$Te with an array of 988 TeO$_2$ crystals operated as bolometers at $\sim$10 mK in a large dilution refrigerator. With this detector, we aim for a $^{130}$Te $0\nu\beta\beta$ decay half-life sensitivity of $9\times10^{25}$ y with 5 y of live time, and a background index of $\lesssim 10^{-2}$ counts/keV/kg/y. Making an effort to maintain radiopurity by minimizing the bolometers' exposure to radon gas during their installation in the cryostat, we perform all operations inside a dedicated cleanroom environment with a controlled radon-reduced atmosphere. In this paper, we discuss the design and performance of the CUORE Radon Abatement System and cleanroom, as well as a system to monitor the radon level in real time.Comment: 10 pages, 6 figures, 1 tabl

Galileo imaging results from the second Earth-Moon flyby: Lunar Maria and related units

The second flyby of the Earth-Moon System by Galileo occurred on December 7, 1992, on its trajectory toward Jupiter. The flyby took the spacecraft over the lunar north polar region from the dark farside and continued across the illuminated nearside. This provided the first opportunity to observe northern and northeastern limb regions with a modern, multispectral imaging system with high spatial resolution (up to 1.1 km/pixel). Scientific objectives included compositional assessment of previously uncharacterized mare regions, study of various light plains materials, and assessment of dark mantle deposits (DMD) and dark halo craters (DHC). Color composite images were prepared from ratios of Galileo SSI filter data (0.76/0.41 yields red; 0.76/0.99 yields green; 0.41/0.76 yields blue) and used for preliminary comparison of units. The 0.41/0.76 ratio has been empirically correlated to Ti content of mare soils (blue is relatively high, red is relatively low). The relative strengths of the ferrous one micron absorption in mafic minerals can be compared using the 0.76/0.99 ratio. In addition, relative ages of units analyzed spectrally were determined from crater statistics using Lunar Orbiter images following the techniques of Neukum et al. Mare deposits analyzed include Mare Humboldtianum, central and eastern Mare Frigoris, Mare Crisium and other deposits in the Crisium Basin, and isolated mare patches on the northeastern lunar limb. Preliminary results show a diversity of 0.41/0.76 micron signatures, implying a wide range of titanium contents. Some light plains units are similar to units found at the Apollo 16 site; others may be ancient mare materials. Dark mantle deposits (DMD) analyzed also are available

Measurement of the Branching Fraction for B- --> D0 K*-

We present a measurement of the branching fraction for the decay B- --> D0 K*- using a sample of approximately 86 million BBbar pairs collected by the BaBar detector from e+e- collisions near the Y(4S) resonance. The D0 is detected through its decays to K- pi+, K- pi+ pi0 and K- pi+ pi- pi+, and the K*- through its decay to K0S pi-. We measure the branching fraction to be B.F.(B- --> D0 K*-)= (6.3 +/- 0.7(stat.) +/- 0.5(syst.)) x 10^{-4}.Comment: 7 pages, 1 postscript figure, submitted to Phys. Rev. D (Rapid Communications

Production of Radioactive Isotopes through Cosmic Muon Spallation in KamLAND

Radioactive isotopes produced through cosmic muon spallation are a background for rare-event detection in $\nu$ detectors, double-$\beta$-decay experiments, and dark-matter searches. Understanding the nature of cosmogenic backgrounds is particularly important for future experiments aiming to determine the pep and CNO solar neutrino fluxes, for which the background is dominated by the spallation production of $^{11}$C. Data from the Kamioka liquid-scintillator antineutrino detector (KamLAND) provides valuable information for better understanding these backgrounds, especially in liquid scintillators, and for checking estimates from current simulations based upon MUSIC, FLUKA, and GEANT4. Using the time correlation between detected muons and neutron captures, the neutron production yield in the KamLAND liquid scintillator is measured to be $(2.8 \pm 0.3) \times 10^{-4} \mu^{-1} g^{-1} cm^{2}$. For other isotopes, the production yield is determined from the observed time correlation related to known isotope lifetimes. We find some yields are inconsistent with extrapolations based on an accelerator muon beam experiment.Comment: 16 pages, 20 figure

A Study of Time-Dependent CP-Violating Asymmetries and Flavor Oscillations in Neutral B Decays at the Upsilon(4S)

We present a measurement of time-dependent CP-violating asymmetries in neutral B meson decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The data sample consists of 29.7 ${\rm fb}^{-1}$ recorded at the $\Upsilon(4S)$ resonance and 3.9 ${\rm fb}^{-1}$ off-resonance. One of the neutral B mesons, which are produced in pairs at the $\Upsilon(4S)$, is fully reconstructed in the CP decay modes $J/\psi K^0_S$, $\psi(2S) K^0_S$, $\chi_{c1} K^0_S$, $J/\psi K^{*0}$ ($K^{*0}\to K^0_S\pi^0$) and $J/\psi K^0_L$, or in flavor-eigenstate modes involving $D^{(*)}\pi/\rho/a_1$ and $J/\psi K^{*0}$ ($K^{*0}\to K^+\pi^-$). The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. The proper time elapsed between the decays is determined by measuring the distance between the decay vertices. A maximum-likelihood fit to this flavor eigenstate sample finds $\Delta m_d = 0.516\pm 0.016 {\rm (stat)} \pm 0.010 {\rm (syst)} {\rm ps}^{-1}$. The value of the asymmetry amplitude $\sin2\beta$ is determined from a simultaneous maximum-likelihood fit to the time-difference distribution of the flavor-eigenstate sample and about 642 tagged $B^0$ decays in the CP-eigenstate modes. We find $\sin2\beta=0.59\pm 0.14 {\rm (stat)} \pm 0.05 {\rm (syst)}$, demonstrating that CP violation exists in the neutral B meson system. (abridged)Comment: 58 pages, 35 figures, submitted to Physical Review

Search for the W-exchange decays B0 --> Ds(*)- Ds(*)+

We report a search for the decays $B^{0} \to D_{s}^{-} D_{s}^{+}$, $B^{0} \to D_{s}^{*-} D_{s}^{+}$, $B^{0} \to D_{s}^{*-} D_{s}^{*+}$ in a sample of 232 million $\Upsilon(4S)$ decays to \BBb ~pairs collected with the \babar detector at the PEP-II asymmetric-energy $e^+ e^-$ storage ring. We find no significant signal and set upper bounds for the branching fractions: ${\cal B}(B^{0} \to D_{s}^{-} D_{s}^{+}) < 1.0 \times 10^{-4}, {\cal B}(B^{0} \to D_{s}^{*-} D_{s}^{+}) < 1.3 \times 10^{-4}$ and ${\cal B}(B^{0} \to D_{s}^{*-} D_{s}^{*+}) < 2.4 \times 10^{-4}$ at 90% confidence level.Comment: 8 pages, 2 figures, submitted to PRD-R

Evidence for the Rare Decay B -> K*ll and Measurement of the B -> Kll Branching Fraction

We present evidence for the flavor-changing neutral current decay $B\to K^*\ell^+\ell^-$ and a measurement of the branching fraction for the related process $B\to K\ell^+\ell^-$, where $\ell^+\ell^-$ is either an $e^+e^-$ or $\mu^+\mu^-$ pair. These decays are highly suppressed in the Standard Model, and they are sensitive to contributions from new particles in the intermediate state. The data sample comprises $123\times 10^6$ $\Upsilon(4S)\to B\bar{B}$ decays collected with the Babar detector at the PEP-II $e^+e^-$ storage ring. Averaging over $K^{(*)}$ isospin and lepton flavor, we obtain the branching fractions ${\mathcal B}(B\to K\ell^+\ell^-)=(0.65^{+0.14}_{-0.13}\pm 0.04)\times 10^{-6}$ and ${\mathcal B}(B\to K^*\ell^+\ell^-)=(0.88^{+0.33}_{-0.29}\pm 0.10)\times 10^{-6}$, where the uncertainties are statistical and systematic, respectively. The significance of the $B\to K\ell^+\ell^-$ signal is over $8\sigma$, while for $B\to K^*\ell^+\ell^-$ it is $3.3\sigma$.Comment: 7 pages, 2 postscript figues, submitted to Phys. Rev. Let

Measurement of the B+ --> p pbar K+ Branching Fraction and Study of the Decay Dynamics

With a sample of 232x10^6 Upsilon(4S) --> BBbar events collected with the BaBar detector, we study the decay B+ --> p pbar K+ excluding charmonium decays to ppbar. We measure a branching fraction Br(B+ --> p pbar K+)=(6.7+/-0.5+/-0.4)x10^{-6}. An enhancement at low ppbar mass is observed and the Dalitz plot asymmetry suggests dominance of the penguin amplitude in this B decay. We search for a pentaquark candidate Theta*++ decaying into pK+ in the mass range 1.43 to 2.00 GeV/c2 and set limits on Br(B+ --> Theta*++pbar)xBr(Theta*++ --> pK+) at the 10^{-7} level.Comment: 8 pages, 7 postscript figures, submitted to Phys. Rev. D (Rapid Communications