119115506
High-precision measurement of atmospheric mass-squared splitting with T2K and NOvA
A precise measurement of the atmospheric mass-squared splitting |\Delta m^2_{\mu\mu}| is crucial to establish the three-flavor paradigm and to constrain the neutrino mass models. In addition, a precise value of |\Delta m^2_{\mu\mu}| will significantly enhance the hierarchy reach of future medium-baseline reactor experiments like JUNO and RENO-50. In this work, we explore the precision in |\Delta m^2_{\mu\mu}| that will be available after the full runs of T2K and NOvA. We find that the combined data will be able to improve the precision in |\Delta m^2_{\mu\mu}| to sub-percent level for maximal 2-3 mixing. Depending on the true value of \sin^2\theta_{23} in the currently-allowed 3 sigma range, the precision in |\Delta m^2_{\mu\mu}| will vary from 0.87% to 1.24%. We further demonstrate that this is a robust measurement as it remains almost unaffected by the present uncertainties in \theta_{13}, \delta_{CP}, the choice of mass hierarchy, and the systematic errors.
117196215
Studies of non-standard effects in atmospheric neutrino oscillations of Super-Kamiokande
119244677
Target mass monitoring and instrumentation in the Daya Bay antineutrino detectors
The Daya Bay experiment measures sin 22θ13 using functionally identical antineutrino detectors located at distances of 300 to 2000 meters from the Daya Bay nuclear power complex. Each detector consists of three nested fluid volumes surrounded by photomultiplier tubes. These volumes are coupled to overflow tanks on top of the detector to allow for thermal expansion of the liquid. Antineutrinos are detected through the inverse beta decay reaction on the proton-rich scintillator target. A precise and continuous measurement of the detector's central target mass is achieved by monitoring the the fluid level in the overflow tanks with cameras and ultrasonic and capacitive sensors. In addition, the monitoring system records detector temperature and levelness at multiple positions. This monitoring information allows the precise determination of the detectors' effective number of target protons during data taking. We present the design, calibration, installation and in-situ tests of the Daya Bay real-time antineutrino detector monitoring sensors and readout electronics.
120923082
Constraints on sterile neutrinos using Super-Kamiokande I atmospheric neutrino data
118791439
Reactor Neutrino Experiments: $\theta_{13}$ and Beyond
We review the current-generation short-baseline reactor neutrino experiments that have firmly established the third neutrino mixing angle $\theta_{13}$ to be non-zero. The relative large value of $\theta_{13}$ (around 9$^\circ$) has opened many new and exciting opportunities for future neutrino experiments. Daya Bay experiment with the first measurement of $\Delta m^2_{ee}$ is aiming for a precision measurement of this atmospheric mass-squared splitting with a comparable precision as $\Delta m^2_{\mu\mu}$ from accelerator muon neutrino experiments. JUNO, a next-generation reactor neutrino experiment, is targeting to determine the neutrino mass hierarchy with medium baselines ($\sim$50 km). Beside these {\color{black} opportunities enabled by the large $\theta_{13}$}, the current-generation (Daya Bay, Double Chooz, and RENO) and the next-generation (JUNO, RENO-50, and PROSPECT) reactor experiments, with their unprecedented statistics, are also leading the precision era of the 3-flavor neutrino oscillation physics as well as constraining new physics beyond the neutrino Standard Model.
118598186
The Daya Bay antineutrino detector filling system and liquid mass measurement
The Daya Bay Reactor Neutrino Experiment has measured the neutrino mixing angle ?13 to world-leading precision. The experiment uses eight antineutrino detectors filled with 20-tons of gadolinium-doped liquid scintillator to detect antineutrinos emitted from the Daya Bay nuclear power plant through the inverse beta decay reaction. The precision measurement of sin22?13 relies on the relative antineutrino interaction rates between detectors at near (400 m) and far (roughly 1.8 km) distances from the nuclear reactors. The measured interaction rate in each detector is directly proportional to the number of protons in the liquid scintillator target. A precision detector filling system was developed to simultaneously fill the three liquid zones of the antineutrino detectors and measure the relative target mass between detectors to < 0.02%. This paper describes the design, operation, and performance of the system and the resulting precision measurement of the detectors' target liquid masses.
8377768
Near-infrared Survey of the GOODS-North Field: Search for Luminous Galaxy Candidates at z 6.5
We present near-infrared (NIR; J and K_s) survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field. The publicly available imaging data were obtained using the MOIRCS instrument on the 8.2 m Subaru and the WIRCam instrument on the 3.6 m Canada-France-Hawaii Telescope (CFHT). These observations fulfill a serious wavelength gap in the GOODS-N data, i.e., lack of deep NIR observations. We combine the Subaru/MOIRCS and CFHT/WIRCam archival data to generate deep J- and K_s-band images, covering the full GOODS-N field (~169 arcmin^2) to an AB magnitude limit of ~25 mag (3σ). We applied z_850-band dropout color selection criteria, using the NIR data generated here. We have identified two possible Lyman break galaxy (LBG) candidates at z ≳ 6.5 with J ≲ 24.5. The first candidate is a likely LBG at z ≃ 6.5 based on a weak spectral feature tentatively identified as Lyα line in the deep Keck/DEIMOS spectrum, while the second candidate is a possible LBG at z ≃ 7 based on its photometric redshift. These z 850-dropout objects, if confirmed, are among the brightest such candidates found so far. At z ≳ 6.5, their star formation rate is estimated as 100-200 M_☉ yr^(–1). If they continue to form stars at this rate, they assemble a stellar mass of ~5 × 10^(10) M_☉ after about 400 million years, becoming the progenitors of massive galaxies observed at z ≃ 5. We study the implication of the z 850-band dropout candidates discovered here, in constraining the bright end of the luminosity function and understanding the nature of high-redshift galaxies.
119117635
ALMA SUBMILLIMETER CONTINUUM IMAGING OF THE HOST GALAXIES OF GRB 021004 AND GRB 080607
We report 345 GHz continuum observations of the host galaxies of gamma-ray bursts (GRBs) 021004 and 080607 at z > 2 using the Atacama Large Millimeter/Submillimeter Array (ALMA) in Cycle 0. Of the two bursts, GRB 021004 is one of the few GRBs that originate in a Lyman limit host, while GRB 080607 is classified as a 'dark burst' and its host galaxy is a candidate of dusty star-forming galaxy at z {approx} 3. With an order of magnitude improvement in the sensitivities of the new imaging searches, we detect the host galaxy of GRB 080607 with a flux of S{sub 345} = 0.31 {+-} 0.09 mJy and a corresponding infrared luminosity of L{sub IR} = (2.4-4.5) Multiplication-Sign 10{sup 11} L{sub Sun }. However, the host galaxy of GRB 021004 remains undetected and the ALMA observations allow us to place a 3{sigma} upper limit of L{sub IR} < 3.1 Multiplication-Sign 10{sup 11} L{sub Sun} for the host galaxy. The continuum imaging observations show that the two galaxies are not ultraluminous infrared galaxies, but are at the faintest end of the dusty galaxy population that gives rise to the submillimeter extragalactic background light. The derived star formation rates of the twomore » GRB host galaxies are less than 100 M{sub Sun} yr{sup -1}, which are broadly consistent with optical measurements. The result suggests that the large extinction (A{sub V} {approx} 3) in the afterglow of GRB 080607 is confined along its particularly dusty sight line, and not representative of the global properties of the host galaxy.« less
201858169
KAON-NUCLEON AND ANTI-KAON-NUCLEON INTERACTIONS IN A CONSTITUENT QUARK MODEL
A combined study of the KN and KN interactions is performed within a chiral constituent quark model with the parameters fitted by the masses of the octet and decuplet baryon ground states. The S, P , D, F wave KN phase shifts and the cross sections for K−p scattering into K−p, Kn, π+Σ−, π−Σ+, πΣ and πΛ channels are dynamically calculated by solving a resonating group method (RGM) equation. A satisfactory agreement with the experimental data is obtained, and at the same time, the results show that both one-gluon exchange (OGE) and vector meson exchange are necessary to be included in the quark-quark interacting potentials if one tries to simultaneously describe the KN phase shifts and KN cross sections in a constituent quark model.
119104367
Ultradeep KS Imaging in the GOODS-N
We present an ultradeep KS -band image that covers 0.5 × 0.5 deg2 centered on the Great Observatories Origins Deep Survey-North (GOODS-N). The image reaches a 5σ depth of in the GOODS-N region, which is as deep as the GOODS-N Spitzer Infrared Array Camera (IRAC) 3.6 μm image. We present a new method of constructing IRAC catalogs that uses the higher spatial resolution KS image and catalog as priors and iteratively subtracts fluxes from the IRAC images to estimate the IRAC fluxes. Our iterative method is different from the χ2 approach adopted by other groups. We verified our results using data taken in two different epochs of observations, as well as by comparing our colors with the colors of stars and with the colors derived from model spectral energy distributions of galaxies at various redshifts. We make available to the community our WIRCam KS -band image and catalog (94,951 objects in 0.25 deg2), the Interactive Data Language pipeline used for reducing the WIRCam images, and our IRAC 3.6-8.0 μm catalog (16,950 objects in 0.06 deg2 at 3.6 μm). With this improved KS and IRAC catalog and a large spectroscopic sample from our previous work, we study the color-magnitude and color-color diagrams of galaxies. We compare the effectiveness of using KS and IRAC colors to select active galactic nuclei and galaxies at various redshifts. We also study a color selection of z = 0.65-1.2 galaxies using the KS , 3.6 μm, and 4.5 μm bands.
118328393
Clustering Properties of BzK-selected Galaxies in GOODS-N: Environmental Quenching and Triggering of Star Formation at z ~ 2
Using a sample of BzK-selected galaxies at z ~ 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellar mass (M *), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFR∝M α * with α = 0.74 ± 0.20 down to M * ~ 109 M ☉, indicating a weak dependence on the stellar mass of the SFR efficiency, namely, SSFR. We also measure the angular correlation function and hence infer the correlation length for sBzK galaxies as a function of M *, SFR, and SSFR, as well as K-band apparent magnitude. We show that passive galaxies (pBzKs) are more strongly clustered than sBzK galaxies at a given stellar mass, mirroring the color-density relation seen at lower redshifts. We also find that the correlation length of sBzK galaxies ranges from 4 to 20 h –1 Mpc, being a strong function of MK , M *, and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at 2 × 10–9 yr–1, which is the typical value for "main-sequence" star-forming galaxies at z ~ 2. We show that the correlation length reaches a minimum at this characteristic value, and is larger for galaxies with both smaller and larger SSFRs; a dichotomy that is only marginally implied from the predictions of the semi-analytical models. Our results suggest that there are two types of environmental effects at work at z ~ 2. Stronger clustering for relatively quiescent galaxies implies that the environment has started to play a role in quenching star formation. At the same time, stronger clustering for galaxies with elevated SSFRs ("starbursts") might be attributed to an increased efficiency for galaxy interactions and mergers in dense environments.