The RENO experiment reports more precisely measured values of θ_{13} and |Δm_{ee}^{2}| using ∼2200 live days of data. The amplitude and frequency of reactor electron antineutrino (νover ¯_{e}) ...oscillation are measured by comparing the prompt signal spectra obtained from two identical near and far detectors. In the period between August 2011 and February 2018, the far (near) detector observed 103 212 (850 666) νover ¯_{e} candidate events with a background fraction of 4.8% (2.0%). A clear energy and baseline dependent disappearance of reactor νover ¯_{e} is observed in the deficit of the measured number of νover ¯_{e}. Based on the measured far-to-near ratio of prompt spectra, we obtain sin^{2}2θ_{13}=0.0896±0.0048(stat)±0.0047(syst) and |Δm_{ee}^{2}|=2.68±0.12(stat)±0.07(syst)×10^{-3} eV^{2}.
We report a fuel-dependent reactor electron antineutrino (νover ¯_{e}) yield using six 2.8 GW_{th} reactors in the Hanbit nuclear power plant complex, Yonggwang, Korea. The analysis uses 850 666 ...νover ¯_{e} candidate events with a background fraction of 2.0% acquired through inverse beta decay (IBD) interactions in the near detector for 1807.9 live days from August 2011 to February 2018. Based on multiple fuel cycles, we observe a fuel ^{235}U dependent variation of measured IBD yields with a slope of (1.51±0.23)×10^{-43} cm^{2}/fission and measure a total average IBD yield of (5.84±0.13)×10^{-43} cm^{2}/fission. The hypothesis of no fuel-dependent IBD yield is ruled out at 6.6σ. The observed IBD yield variation over ^{235}U isotope fraction does not show significant deviation from the Huber-Mueller (HM) prediction at 1.3 σ. The measured fuel-dependent variation determines IBD yields of (6.15±0.19)×10^{-43} and (4.18±0.26)×10^{-43} cm^{2}/fission for two dominant fuel isotopes ^{235}U and ^{239}Pu, respectively. The measured IBD yield per ^{235}U fission shows the largest deficit relative to the HM prediction. Reevaluation of the ^{235}U IBD yield per fission may mostly solve the reactor antineutrino anomaly (RAA) while ^{239}Pu is not completely ruled out as a possible contributor to the anomaly. We also report a 2.9 σ correlation between the fractional change of the 5 MeV excess and the reactor fuel isotope fraction of ^{235}U.
The Reactor Experiment for Neutrino Oscillation (RENO) has been taking electron antineutrino (ν¯e) data from the reactors in Yonggwang, Korea, using two identical detectors since August 2011. Using ...roughly 500 live days of data through January 2013 we observe 290 775 (31 514) reactor ν¯e candidate events with 2.8% (4.9%) background in the near (far) detector. The observed visible positron spectra from the reactor ν¯e events in both detectors show a discrepancy around 5 MeV with regard to the prediction from the current reactor ν¯e model. Based on a far-to-near ratio measurement using the spectral and rate information, we have obtained sin22θ13=0.082±0.009(stat.)±0.006(syst.) and |Δmee2|=2.62−0.23+0.21(stat.)−0.13+0.12(syst.)×10−3 eV2.
We report a search result for a light sterile neutrino oscillation with roughly 2200 live days of data in the RENO experiment. The search is performed by electron antineutrino (νe) disappearance ...taking place between six 2.8 GW th reactors and two identical detectors located at 294 m (near) and 1383 m (far) from the center of the reactor array. A spectral comparison between near and far detectors can explore reactor νe oscillations to a light sterile neutrino. An observed spectral difference is found to be consistent with that of the three-flavor oscillation model. This yields limits on sin 22θ14 in the 10−4 ≲ | Δm412 | ≲ 0.5 eV2 region, free from reactor νe flux and spectrum uncertainties. The RENO result provides the most stringent limits on sterile neutrino mixing at | Δm412 | ≲ 0.002 eV2 using the νe disappearance channel.
Far-infrared images and photometry are presented for 201 Luminous and Ultraluminous Infrared Galaxies LIRGs: log (L sub(IR)/L sub(middot in circle)) = 11.00-11.99, ULIRGs: log (L sub(IR)/L sub(middot ...in circle)) = 12.00-12.99, in the Great Observatories All-Sky LIRG Survey (GOALS), based on observations with the Herschel Space Observatory Photodetector Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) instruments. The image atlas displays each GOALS target in the three PACS bands (70, 100, and 160 mu m) and the three SPIRE bands (250, 350, and 500 mu m), optimized to reveal structures at both high and low surface brightness levels, with images scaled to simplify comparison of structures in the same physical areas of ~100 x 100 kpc super(2). Flux densities of companion galaxies in merging systems are provided where possible, depending on their angular separation and the spatial resolution in each passband, along with integrated system fluxes (sum of components). This data set constitutes the imaging and photometric component of the GOALS Herschel OT1 observing program, and is complementary to atlases presented for the Hubble Space Telescope, Spitzer Space Telescope, and Chandra X-ray Observatory. Collectively, these data will enable a wide range of detailed studies of active galactic nucleus and starburst activity within the most luminous infrared galaxies in the local universe.
A
bstract
The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors since August 2011. The experiment has observed the ...disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen (n-H). Based on 1500 live days of data taken with 16.8 GW
th
reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino candidate events with the n-H data. This provides an independent measurement of neutrino mixing angle
θ
13
and a consistency check on the validity of the result obtained from the data with neutron capture on Gadolinium (n-Gd). Furthermore, it provides an important cross-check on the systematic uncertainties of the n-Gd measurement. Based on a rate-only analysis, we obtain sin
2
2
θ
13
= 0
.
086 ± 0
.
008(stat
.
) ± 0
.
014(syst
.
). The combination of this result with that of n-Gd is also reported.
ABSTRACT
We report the results from a comprehensive study of 74 ultraluminous infrared
galaxies (ULIRGs) and 34 Palomar-Green (PG) quasars within
z
∼
0.3 observed with the
Spitzer
Infrared ...Spectrograph (IRS). The
contribution of nuclear activity to the bolometric luminosity in these systems
is quantified using six independent methods that span a range in wavelength and
give consistent results within ∼±10%–15% on average. This agreement suggests
that deeply buried active galactic nuclei (AGNs) invisible to
Spitzer
IRS but bright in the far-infrared are not common
in this sample. The average derived AGN contribution in ULIRGs is ∼35%–40%,
ranging from ∼15%–35% among “cool”
(
f
25
/
f
60
⩽ 0.2)
optically classified H
ii
-like and LINER ULIRGs to ∼50 and ∼75% among
warm Seyfert 2 and Seyfert 1 ULIRGs, respectively. This number exceeds ∼80% in
PG QSOs. ULIRGs fall in one of three distinct AGN classes: (1) objects with
small extinctions and large polycyclic aromatic hydrocarbon (PAH) equivalent
widths are highly starburst-dominated; (2) systems with large extinctions and
modest PAH equivalent widths have larger AGN contributions, but still tend to be
starburst-dominated; and (3) ULIRGs with both small extinctions and small PAH
equivalent widths host AGN that are at least as powerful as the starbursts. The
AGN contributions in class 2 ULIRGs are more uncertain than in the other
objects, and we cannot formally rule out the possibility that these objects
represent a physically distinct type of ULIRGs. A morphological trend is seen
along the sequence (1)–(2)–(3), in general agreement with the standard ULIRG−QSO
evolution scenario and suggestive of a broad peak in extinction during the
intermediate stages of merger evolution. However, the scatter in this sequence,
including the presence of a significant number of AGN-dominated systems prior to
coalescence and starburst-dominated but fully merged systems, implies that black
hole accretion, in addition to depending on the merger phase, also has a strong
chaotic/random component, as in local AGNs.
Heisenberg interactions are ubiquitous in magnetic materials and play a central role in modelling and designing quantum magnets. Bond-directional interactions offer a novel alternative to Heisenberg ...exchange and provide the building blocks of the Kitaev model, which has a quantum spin liquid as its exact ground state. Honeycomb iridates, A2 IrO3 (A = Na, Li), offer potential realizations of the Kitaev magnetic exchange coupling, and their reported magnetic behaviour may be interpreted within the Kitaev framework. However, the extent of their relevance to the Kitaev model remains unclear, as evidence for bond-directional interactions has so far been indirect. Here we present direct evidence for dominant bond-directional interactions in antiferromagnetic Na2 IrO3 and show that they lead to strong magnetic frustration. Diffuse magnetic X-ray scattering reveals broken spin-rotational symmetry even above the Néel temperature, with the three spin components exhibiting short-range correlations along distinct crystallographic directions. This spin- and real-space entanglement directly uncovers the bond-directional nature of these interactions, thus providing a direct connection between honeycomb iridates and Kitaev physics.
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