We present an improved search for neutrinoless double-beta (0νββ) decay of 136 Xe in the KamLANDZen experiment. Owing to purification of the xenon-loaded liquid scintillator, we achieved a significant reduction of the 110m Ag contaminant identified in previous searches. Combining the results from the first and second phase, we obtain a lower limit for the 0νββ decay half-life of T 0ν 1=2 > 1.07 × 10 26 yr at 90% C.L., an almost sixfold improvement over previous limits. Using commonly adopted nuclear matrix element calculations, the corresponding upper limits on the effective Majorana neutrino mass are in the range 61-165 meV. For the most optimistic nuclear matrix elements, this limit reaches the bottom of the quasidegenerate neutrino mass region. DOI: 10.1103/PhysRevLett.117.082503 Neutrinoless double-beta (0νββ) decay is an exotic nuclear process predicted by extensions of the Standard Model of particle physics. Observation of this decay demonstrates the nonconservation of lepton number, and proves that neutrinos have a Majorana mass component. In the framework of light Majorana neutrino exchange, its decay rate is proportional to the square of the effective Majorana neutrino mass hm ββ i ≡ j P i U 2 ei m ν i j. ) provide upper limits on hm ββ i of ∼0.2-0.4 eV using available nuclear matrix element (NME) values from the literature. The sensitivities of these searches correspond to mass scales in the so-called quasidegenerate mass region.KamLAND-Zen is a double-beta decay experiment that exploits the existing detection infrastructure and radiopurity of KamLAND [5,6]. The KamLAND-Zen detector consists of 13 tons of Xe-loaded liquid scintillator (Xe-LS) contained in a 3.08-m-diameter spherical inner balloon (IB) located at the center of the KamLAND detector. The IB is constructed from 25-μm-thick transparent nylon film and is surrounded by 1 kton of liquid scintillator (LS) contained in a 13-m-diameter spherical outer balloon. The outer LS acts as an active shield. The scintillation photons are viewed by 1879 photomultiplier tubes (PMTs) mounted on the inner surface of the containment vessel. The Xe-LS consists of 80.7% decane and 19.3% pseudocumene (1,2,4-trimethylbenzene) by volume, 2.29 g=liter of the fluor PPO (2,5-diphenyloxazole), and ð2.91 AE 0.04Þ% by weight of isotopically enriched xenon gas. The isotopic abundances in the enriched xenon were measured by a residual gas analyzer to be ð90.77 AE 0.08Þ% 136 Xe, ð8.96AE 0.02Þ% 134 Xe. Other xenon isotopes have negligible presence. The two electrons emitted from 136 Xe ββ decay

This corrects the article DOI: 10.1103/PhysRevLett.117.082503.

N-type ZnTe layers with high electron concentration are grown by molecular-beam epitaxy using aluminum as the donor species. The ZnTe:Al layers show a high structural quality with a narrow x-ray diffraction linewidth (24 arcsec) and a high carrier concentration up to n=4×1018 cm−3 with low resistivity (ρ=0.017 Ω cm). The dependence of the electron mobility on the carrier concentration suggests that the dominant scattering mechanisms in the ZnTe:Al layers are ionized impurity scattering and polar optical phonon scattering. The photoluminescence spectrum of moderately doped ZnTe layers shows strong Al–donor-related bound exciton lines: I2 (2.378 eV) and donor–acceptor pair emission (zero phonon energy=2.324 eV) with a weak deep-level emission (2.19 eV). Highly Al-doped layers show an increase in the deep-level emission intensity and a decrease in carrier mobility, which are interpreted in terms of the increase in the carrier compensation.

-We present a search for low energy antineutrino events coincident with the gravitational wave events GW150914 and GW151226, and the candidate event LVT151012 using KamLAND, a kiloton-scale antineutrino detector. We find no inverse beta-decay neutrino events within ±500 seconds of either gravitational wave signal. This non-detection is used to constrain the electron antineutrino fluence and the total integrated luminosity of the astrophysical sources.

We have investigated the ZnTe-based material system for the application to light-emitting devices. To this end, ZnTe homoepitaxy techniques have been developed to grow high-quality epitaxial layers. The conductivity control of ZnTe and ZnMgSeTe layers have been investigated. High structural quality n-type ZnTe layers with high carrier concentration are achieved by aluminum doping. Ambipolar conductivity control of quaternary layers is achieved. Aluminum doped ZnMgSeTe layers show a net carrier concentration of 5 Â 10 16 cm À3 , while a high hole concentration of 2.5 Â 10 19 cm À3 is achieved by p-type doping using a nitrogen plasma source. Based on those results, Zn 1Àx Cd x Te/ZnMgSeTe triple-quantum-well(TQW) LED structures were fabricated. Bright electroluminescence was obtained at room temperature at the wavelength of 604 nm from Zn 0:7 Cd 0:3 Te and at 566 nm from Zn 0:85 Cd 0:15 Te TQW-LED.Introduction Devices emitting light at around 550 nm are strongly needed for several important applications such as medical, plastic optical fiber communication, and full color laser display applications. Although laser diodes (LDs) for violet to blue-green and red wavelength ranges are now commercially available, no succesful report on LDs in the wavelength range from the pure-green to yellow (l = 540-580 nm) have been reported yet. Moreover, the conversion efficiency of light-emitting diodes (LEDs) in this wavelength region is extremely low in comparison with that of blue and red LEDs [1].ZnTe has a direct band gap of 2.27 eV (546 nm) at room temperature, therefore it is one of the most important materials for the pure-green wavelength (l = 550 nm) region. Because of the importance of ZnTe, there have been continuous attempts to fabricate ZnTe-based LEDs. Homo-junction LEDs were fabricated by diffusion of donor impurities [2,3]. However, ZnTe-based heterojunction LEDs have not been demonstrated yet, mainly due to the problems in growing highly doped n-type epitaxial layers with high crystal quality.In this paper, molecular beam epitaxy of ZnTe-based high-quality thin films by homoepitaxy technique is reported. The conductivity control of ZnTe-based materials is investigated using aluminum and nitrogen plasma sources as a n-and p-type dopants. Heterojunction LED strutures are fabricated and current injected operation at room temperature is demonstrated.