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

The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for largescale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the AT-LAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.

We present results from the first phase of the KamLAND-Zen double-beta decay experiment, corresponding to an exposure of 89.5 kg yr of 136 Xe. We obtain a lower limit for the neutrinoless double-beta decay half-life of T 0ν 1/2 > 1.9 × 10 25 yr at 90% C.L. The combined results from KamLAND-Zen and EXO-200 give T 0ν 1/2 > 3.4 × 10 25 yr at 90% C.L., which corresponds to a Majorana neutrino mass limit of m ββ < (120 − 250) meV based on a representative range of available matrix element calculations. Using those calculations, this result excludes the Majorana neutrino mass range expected from the neutrinoless double-beta decay detection claim in 76 Ge, reported by a part of the Heidelberg-Moscow Collaboration, at more than 97.5% C.L. 21.10.Tg, 14.60.Pq, 27.60.+j Double-beta (ββ) decay is a rare nuclear process observable in even-even nuclei for which ordinary beta decay is energetically forbidden or highly suppressed by large spin differences. Standard ββ decay proceeds by a second-order weak interaction emitting two electron anti neutrinos and two electrons (2νββ). If, however, the neutrino is a massive Majorana particle, ββ decay might also occur without the emission of neutrinos (0νββ). Observation of such a process would demonstrate that lepton number is not conserved in nature. Moreover, if the process is mediated by the exchange of a light left-handed neutrino, its rate increases with the square of the effective Majorana neutrino mass m ββ ≡ Σ i U 2 ei m νi , and hence its measurement would provide information on the absolute neutrino mass scale. To date there has been only one claimed observation of 0νββ decay, in 76 Ge [1].At present there are several operating experiments performing 0νββ decay searches with design sensitivities sufficient to test the Majorana neutrino mass implied by the claim in [1] within a few years of running: GERDA with 76 Ge, CUORE-0 with 130 Te, and EXO-200 and KamLAND-Zen with 136 Xe. Among those experiments, KamLAND-Zen released its first 0νββ half-life limit, T 0ν 1/2 > 5.7 × 10 24 yr at 90% C.L., based on a 27.4 kg yr exposure [2]. Although the sensitivity of this result was impeded by the presence of an unexpected background peak just above the 2.458 MeV Q value of 136 Xe ββ decay, the Majorana neutrino mass sensitivity was similar to that in Ref. [1]. EXO-200 later improved on this limit by a factor of 2.8 [3], constraining the result in [1] for a number of nuclear matrix element (NME) calculations.As shown below, we have found the problematic background peak in the KamLAND-Zen spectrum to most likely come from metastable 110m Ag. We embarked recently on a purification campaign to remove this isotope. Doing so required extracting the Xe from the detector, thus marking the end of the first phase of KamLAND-Zen. In this Letter we report on the full data set from the first phase of KamLAND-Zen, corresponding to an exposure of 89.5 kg yr of 136 Xe. This represents a factor of 3.2 increase over KamLAND-Zen's first result [2], and is also the largest exposure for a ββ decay isot...

Within the limitations of the present study, it is suggested that monolithic zirconia crown with chamfer width of 0.5 mm and occlusal thickness of 0.5 mm can be used in the molar region in terms of fracture resistance.

SUMMARYBrain ischemia, also termed cerebral ischemia, is a condition in which there is insufficient blood flow to the brain to meet metabolic demand, leading to tissue death (cerebral infarction) due to poor oxygen supply (cerebral hypoxia). Our group is interested in the protective effects of neuropeptides for alleviating brain ischemia, as well as the underlying mechanisms of their action. The present study was initiated to investigate molecular responses at the level of gene expression in ischemic brain tissue. To achieve this, we used a mouse permanent middle cerebral artery occlusion (PMCAO) model in combination with high-throughput DNA microarray analysis on an Agilent microarray platform. Briefly, the right (ipsilateral) and left (contralateral) hemispheres of PMCAO model mice were dissected at two time points, 6 and 24 hours post-ischemia. Total RNA from the ischemic (ipsilateral) hemisphere was subjected to DNA microarray analysis on a mouse whole genome 4x44K DNA chip using a dye-swap approach. Functional categorization using the gene ontology (GO, MGD/AMIGO) of numerous changed genes revealed expression pattern changes in the major categories of cellular process, biological regulation, regulation of biological process, metabolic process and response to stimulus. Reverse-transcriptase PCR (RT-PCR) analysis on randomly selected highly up- or downregulated genes validated, in general, the microarray data. Using two time points for this analysis, major and minor trends in gene expression and/or functions were observed in relation to early- and late-response genes and differentially regulated genes that were further classified into specific pathways or disease states. We also examined the expression of these genes in the contralateral hemisphere, which suggested the presence of bilateral effects and/or differential regulation. This study provides the first ischemia-related transcriptome analysis of the mouse brain, laying a strong foundation for studies designed to elucidate the mechanisms regulating ischemia and to explore the neuroprotective effects of agents such as target neuropeptides.