Neutrino mass hierarchy and precision physics with medium-baseline reactors: Impact of energy-scale and flux-shape uncertainties

Nuclear reactors provide intense sources of electron antineutrinos, characterized by few-MeV energy E and unoscillated spectral shape Phi(E). High-statistics observations of reactor neutrino oscillations over medium-baseline distances L ~ O(50) km would provide unprecedented opportunities to probe both the long-wavelength mass-mixing parameters (delta m^2 and theta_12) and the short-wavelength ones (Delta m^2 and theta_13), together with the subtle interference effects associated with the neutrino mass hierarchy (either normal or inverted). In a given experimental setting - here taken as in the JUNO project for definiteness - the achievable hierarchy sensitivity and parameter accuracy depend not only on the accumulated statistics but also on systematic uncertainties, which include (but are not limited to) the mass-mixing priors and the normalizations of signals and backgrounds. We examine, in addition, the effect of introducing smooth deformations of the detector energy scale, E -> E'(E), and of the reactor flux shape, Phi(E) -> Phi'(E), within reasonable error bands inspired by state-of-the-art estimates. It turns out that energy-scale and flux-shape systematics can noticeably affect the performance of a JUNO-like experiment, both on the hierarchy discrimination and on precision oscillation physics. It is shown that a significant reduction of the assumed energy-scale and flux-shape uncertainties (by, say, a factor of 2) would be highly beneficial to the physics program of medium-baseline reactor projects. Our results also shed some light on the role of the inverse-beta decay threshold, of geoneutrino backgrounds, and of matter effects in the analysis of future reactor oscillation data.Comment: 13 pages, including 17 figures. Minor changes in the text, references added. To appear in Phys. Rev.

Joint short- and long-baseline constraints on light sterile neutrinos

Recent studies provide evidence that long-baseline (LBL) experiments are sensitive to the extra CP phases involved with light sterile neutrinos, whose existence is suggested by several anomalous short-baseline (SBL) results. We show that, within the 3+1 scheme, the combination of the existing SBL data with the LBL results coming from the two currently running experiments, NO\u3bdA and T2K, enables us to simultaneously constrain two active-sterile mixing angles, \u3b814 and \u3b824, and two CP phases, \u3b413 61\u3b4 and \u3b414, although the information on the second CP phase is still weak. The two mixing angles are basically determined by the SBL data, while the two CP phases are constrained by the LBL experiments, once the information coming from the SBL setups is taken into account. We also assess the robustness or fragility of the estimates of the standard 3-flavor parameters in the more general 3+1 scheme. To this regard we find that (i) the indication of CP violation found in the 3-flavor analyses persists also in the 3+1 scheme, with \u3b413 61\u3b4 having still its best-fit value around 12\u3c0/2, (ii) the 3-flavor weak hint in favor of the normal hierarchy becomes even less significant when sterile neutrinos come into play, (iii) the weak indication of nonmaximal \u3b823 (driven by NO\u3bdA disappearance data) persists in the 3+1 scheme, where maximal mixing is disfavored at almost the 90% C.L. in both normal and inverted mass hierarchy, and (iv) the preference in favor of one of the two octants of \u3b823 found in the 3-flavor framework (higher octant for inverted mass hierarchy) is completely washed out in the 3+1 scheme

Status of three-neutrino oscillation parameters, circa 2013

The standard three-neutrino (3nu) oscillation framework is being increasingly refined by results coming from different sets of experiments, using neutrinos from solar, atmospheric, accelerator and reactor sources. At present, each of the known oscillation parameters [the two squared mass gaps (delta m^2, Delta m^2) and the three mixing angles (theta_12}, theta_13, theta_23)] is dominantly determined by a single class of experiments. Conversely, the unknown parameters [the mass hierarchy, the theta_23 octant and the CP-violating phase delta] can be currently constrained only through a combined analysis of various (eventually all) classes of experiments. In the light of recent new results coming from reactor and accelerator experiments, and of their interplay with solar and atmospheric data, we update the estimated N-sigma ranges of the known 3nu parameters, and revisit the status of the unknown ones. Concerning the hierarchy, no significant difference emerges between normal and inverted mass ordering. A slight overall preference is found for theta_23 in the first octant and for nonzero CP violation with sin delta < 0; however, for both parameters, such preference exceeds 1 sigma only for normal hierarchy. We also discuss the correlations and stability of the oscillation parameters within different combinations of data sets.Comment: Updated and revised version, accepted for publication in PRD. The analysis includes the latest (March 2014) T2K disappearance data: all the figures and the numerical results have been updated, and parts of the text have been revised accordingl

Lateral stress evolution in chromium sulfide cermets with varying excess chromium

The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a onedimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium content

Gaze following in multiagent contexts: Evidence for a quorum-like principle

Research shows that humans spontaneously follow another individual’s gaze. However, little remains known on how they respond when multiple gaze cues diverge across members of a social group. To address this question, we presented participants with displays depicting three (Experiment 1) or five (Experiment 2) agents showing diverging social cues. In a three-person group, one individual looking at the target (33% of the group) was sufficient to elicit gaze-facilitated target responses. With a five-person group, however, three individuals looking at the target (60% of the group) were necessary to produce the same effect. Gaze following in small groups therefore appears to be based on a quorum-like principle, whereby the critical level of social information needed for gaze following is determined by a proportion of consistent social cues scaled as a function of group size. As group size grows, greater agreement is needed to evoke joint attention

Mobile health use in low- and high-income countries: an overview of the peer-reviewed literature.

The evolution of mobile phone technology has introduced new possibilities to the field of medicine. Combining technological advances with medical expertise has led to the use of mobile phones in all healthcare areas including diagnostics, telemedicine, research, reference libraries and interventions. This article provides an overview of the peer-reviewed literature, published between 1 August 2006 and 1 August 2011, for the application of mobile/cell phones (from basic text-messaging systems to smartphones) in healthcare in both resource-poor and high-income countries. Smartphone use is paving the way in high-income countries, while basic text-messaging systems of standard mobile phones are proving to be of value in low- and middle-income countries. Ranging from infection outbreak reporting, anti-HIV therapy adherence to gait analysis, resuscitation training and radiological imaging, the current uses and future possibilities of mobile phone technology in healthcare are endless. Multiple mobile phone based applications are available for healthcare workers and healthcare consumers; however, the absolute majority lack an evidence base. Therefore, more rigorous research is required to ensure that healthcare is not flooded with non-evidence based applications and is maximized for patient benefit

Disturbances in groundwater chemical parameters related to seismic and volcanic activity in Kamchatka (Russia)

International audienceStarting from 1992 geochemical data are being collected with a mean sampling frequency of three days in the form of the pH value and of the most common ions and gases in the groundwater in one deep well located in Petropavlovsk, the capital city of Kamchatka (Russia). On 1 January 1996 a strong eruption started from the Karymsky volcano, that is located about 100km far from the well, in the north-northeastern direction. At the same time, a large earthquake (M=6.9) occurred in the Karymsky area. On 5 December 1997 a very large earthquake (M=7.7) occurred offshore, at a distance of 350km from the well and towards the same direction. The analysis of the geochemical data shows clear variations in the raw temporal trends on both cases. For the first event, a clear premonitory phase appeared; for the second one, some pre-seismic variations could be revealed but permanent modifications of the chemistry of the water subsequent to the earthquake are very clear. In both cases the feature of the geochemical variations is consistent with an afflux of new water in the aquifer connected with the well and with an escape of the Carbon dioxide gas from the ground in different directions. A schematic model able to justify such a phenomenology and the connections of the geochemical variations with the previous tectonic activities is proposed

The Microcalorimeter Arrays for a Rhenium Experiment (MARE): a next-generation calorimetric neutrino mass experiment

Neutrino oscillation experiments have proved that neutrinos are massive particles, but can't determine their absolute mass scale. Therefore the neutrino mass is still an open question in elementary particle physics. An international collaboration is growing around the project of Microcalorimeter Arrays for a Rhenium Experiment (MARE) for directly measuring the neutrino mass with a sensitivity of about 0.2eV/c2. Many groups are joining their experiences and technical expertise in a common effort towards this challenging experiment. We discuss the different scenarios and the impact of MARE as a complement of KATRIN.Comment: 3 pages, 1 figure Nucl. Instr. Meth. A, proceedings of LTD11 workshop, Tokyo 200

Evolution of the Red Sequence Giant to Dwarf Ratio in Galaxy Clusters out to z ~ 0.5

We analyze deep g' and r' band data of 97 galaxy clusters imaged with MegaCam on the Canada-France-Hawaii telescope. We compute the number of luminous (giant) and faint (dwarf) galaxies using criteria based on the definitions of de Lucia et al. (2007). Due to excellent image quality and uniformity of the data and analysis, we probe the giant-to-dwarf ratio (GDR) out to z ~ 0.55. With X-ray temperature (Tx) information for the majority of our clusters, we constrain, for the first time, the Tx-corrected giant and dwarf evolution separately. Our measurements support an evolving GDR over the redshift range 0.05 < z < 0.55. We show that modifying the (g'-r'), m_r' and K-correction used to define dwarf and giant selection do not alter the conclusion regarding the presence of evolution. We parameterize the GDR evolution using a linear function of redshift (GDR = alpha * z + beta) with a best fit slope of alpha = 0.88 +/- 0.15 and normalization beta = 0.44 +/- 0.03. Contrary to claims of a large intrinsic scatter, we find that the GDR data can be fully accounted for using observational errors alone. Consistently, we find no evidence for a correlation between GDR and cluster mass (via Tx or weak lensing). Lastly, the data suggest that the evolution of the GDR at z < 0.2 is driven primarily by dry merging of the massive giant galaxies, which when considered with previous results at higher redshift, suggests a change in the dominant mechanism that mediates the GDR.Comment: 20 pages, 15 figures. Accepted to MNRA

The XMM Cluster Survey: The Stellar Mass Assembly of Fossil Galaxies

This paper presents both the result of a search for fossil systems (FSs) within the XMM Cluster Survey and the Sloan Digital Sky Survey and the results of a study of the stellar mass assembly and stellar populations of their fossil galaxies. In total, 17 groups and clusters are identified at z < 0.25 with large magnitude gaps between the first and fourth brightest galaxies. All the information necessary to classify these systems as fossils is provided. For both groups and clusters, the total and fractional luminosity of the brightest galaxy is positively correlated with the magnitude gap. The brightest galaxies in FSs (called fossil galaxies) have stellar populations and star formation histories which are similar to normal brightest cluster galaxies (BCGs). However, at fixed group/cluster mass, the stellar masses of the fossil galaxies are larger compared to normal BCGs, a fact that holds true over a wide range of group/cluster masses. Moreover, the fossil galaxies are found to contain a significant fraction of the total optical luminosity of the group/cluster within 0.5R200, as much as 85%, compared to the non-fossils, which can have as little as 10%. Our results suggest that FSs formed early and in the highest density regions of the universe and that fossil galaxies represent the end products of galaxy mergers in groups and clusters. The online FS catalog can be found at http://www.astro.ljmu.ac.uk/~xcs/Harrison2012/XCSFSCat.html.Comment: 30 pages, 50 figures. ApJ published version, online FS catalog added: http://www.astro.ljmu.ac.uk/~xcs/Harrison2012/XCSFSCat.htm