Solar neutrino physics with low-threshold dark matter detectors

Dark matter detectors will soon be sensitive to Solar neutrinos via two distinct channels: coherent neutrino-nucleus scattering and neutrino electron elastic scattering. We establish an analysis method for extracting Solar model properties and neutrino properties from these measurements, including the possible effects of sterile neutrinos which have been hinted at by some reactor experiments and cosmological measurements. Even including sterile neutrinos, through the coherent scattering channel a 1 ton-year exposure with a low-threshold Germanium detector could improve on the current measurement of the normalization of the $^8$B Solar neutrino flux down to 3% or less. Combining with the elastic scattering data will provide constraints on both the high and low energy survival probability, and will improve on the uncertainty on the active-to-sterile mixing angle by a factor of two. This sensitivity to active-to-sterile transitions is competitive and complementary to forthcoming dedicated short baseline sterile neutrino searches with nuclear decays.Comment: 12 pages, 4 figures, 3 table

Implication of neutrino backgrounds on the reach of next generation dark matter direct detection experiments

As direct dark matter experiments continue to increase in size, they will become sensitive to neutrinos from astrophysical sources. For experiments that do not have directional sensitivity, coherent neutrino scattering (CNS) from several sources represents an important background to understand, as it can almost perfectly mimic an authentic WIMP signal. Here we explore in detail the effect of neutrino backgrounds on the discovery potential of WIMPs over the entire mass range of 500 MeV to 10 TeV. We show that, given the theoretical and measured uncertainties on the neutrino backgrounds, direct detection experiments lose sensitivity to light (~10 GeV) and heavy (~100 GeV) WIMPs with a spin-independent cross section below 10^{-45} cm^2 and 10^{-49} cm^2, respectively.Comment: 15 pages, 12 figures, 7Be fluxes revised, conclusions unchange

Complementarity of dark matter detectors in light of the neutrino background

Direct detection dark matter experiments looking for WIMP-nucleus elastic scattering will soon be sensitive to an irreducible background from neutrinos which will drastically affect their discovery potential. Here we explore how the neutrino background will affect future ton-scale experiments considering both spin-dependent and spin-independent interactions. We show that combining data from experiments using different targets can improve the dark matter discovery potential due to target complementarity. We find that in the context of spin-dependent interactions, combining results from several targets can greatly enhance the subtraction of the neutrino background for WIMP masses below 10 GeV/c$^2$ and therefore probe dark matter models to lower cross-sections. In the context of target complementarity, we also explore how one can tune the relative exposures of different target materials to optimize the WIMP discovery potential.Comment: 13 pages, 12 figures, 3 table

A {\mu}-TPC detector for the characterization of low energy neutron fields

The AMANDE facility produces monoenergetic neutron fields from 2 keV to 20 MeV for metrological purposes. To be considered as a reference facility, fluence and energy distributions of neutron fields have to be determined by primary measurement standards. For this purpose, a micro Time Projection Chamber is being developed to be dedicated to measure neutron fields with energy ranging from 8 keV up to 1 MeV. In this work we present simulations showing that such a detector, which allows the measurement of the ionization energy and the 3D reconstruction of the recoil nucleus, provides the determination of neutron energy and fluence of these neutron fields

Micromegas detector developments for MIMAC

The aim of the MIMAC project is to detect non-baryonic Dark Matter with a directional TPC. The recent Micromegas efforts towards building a large size detector will be described, in particular the characterization measurements of a prototype detector of 10 $\times$ 10 cm$^2$ with a 2 dimensional readout plane. Track reconstruction with alpha particles will be shown.Comment: 8 pages, 7 figures Proceedings of the 3rd International conference on Directional Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 2011; corrections on author affiliation

Triggering social interactions:chimpanzees respond to imitation by a humanoid robot and request responses from it

Even the most rudimentary social cues may evoke affiliative responses in humans and promote socialcommunication and cohesion. The present work tested whether such cues of an agent may also promotecommunicative interactions in a nonhuman primate species, by examining interaction-promoting behavioursin chimpanzees. Here, chimpanzees were tested during interactions with an interactive humanoid robot, whichshowed simple bodily movements and sent out calls. The results revealed that chimpanzees exhibited twotypes of interaction-promoting behaviours during relaxed or playful contexts. First, the chimpanzees showedprolonged active interest when they were imitated by the robot. Second, the subjects requested ‘social’responses from the robot, i.e. by showing play invitations and offering toys or other objects. This study thusprovides evidence that even rudimentary cues of a robotic agent may promote social interactions inchimpanzees, like in humans. Such simple and frequent social interactions most likely provided a foundationfor sophisticated forms of affiliative communication to emerge

D-SERINE CONTRIBUTES TO β-AMYLOID-DEPENDENT PATHOPHYSIOLOGYIN ALZHEIMER’S DISEASE

International audienceB fEPSP/PFV ra>o 0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6 WT 5xFAD 5xFAD/SR-/-+ D-s e ri n e + D-s e ri n e + D-s e ri n e Key regulators of the structural and funcFonal brain plasFcity, the N-methyl-D-aspartate subtype of glutamate receptors (NMDARs) requires the binding of the co-agonist D-serine to be acFvated. In Alzheimer's disease (AD), soluble oligomers of the beta-amyloid pepFde (Aßo) affect NMDARs possibly through mechanisms involving changes in D-serine levels since Aßo sFmulate in vitro the producFon of the co-agonist. In this study, we asked whether D-serine contributes in vivo to morpho-funcFonal NMDAR-related deregulaFons mediated by Aßo. Behavioral analysis combined to electrophysiological recordings at CA1/CA3 hippocampal synapses have been thus conducted in the 5xFAD transgenic mice model of amyloïdogenesis displaying marked increase in Aßo rates and compared to 5xFAD animals in which the homozygous gene of the serine racemase (SR) that synthesizes D-serine, has been jointly invalidated. Our results therefore show that deleFon of serine racemase prevents memory-related behavioral deficits observed in mice with prominent features of amyloidogenesis as well as impairment of NMDAR-dependent funcFonal plasFcity, suggesFng a significant contribuFon of D-serine in NMDAR-dependent β-amyloid-related pathophysiology of Alzheimer's disease. EXPERIMENTAL PROCEDURES 1) Behavioral analysis: 8-min spontaneous alternaFon test was performed in a Y maze apparatus to assess working memory performances in 10-12 months of aged mice. Successive entry of the three arms of the maze was considered as an alternaFon. The percentage of alternaFon was calculated as follows: number of alternaFons / (total number of arms visited-2) x 100. 2) Electrophysiology: Hippocampal slices (400 µm thickness) were cut from two groups of WT, 5xFAD/SR +/+ and 5xFAD/SR-/-mice aged 3-4 or 10-12 months. Field excitatory postsynapFc potenFals (fEPSPs) and presynapFc fiber volley (PFV) were extracellularly recorded in CA1 stratum radiatum aner electrical sFmulaFon of Schaffer collaterals. Input/output curves of the fEPSP/PFV raFo of isolated NMDAr-mediated fEPSPs were constructed in a low magnesium medium supplemented with the non-NMDAr antagonist NBQX (10µM) before and 15 min aner addiFon of D-serine (100 µM). High frequency (HFS)-induced long-term potenFaFon (LTP) was studied in control medium aner tetanic sFmulaFon consisFng in one train at 100 Hz delivered for 1 sec. TesFng sFmulaFon was then resumed for 60 min aner HFS. 3) Semi-quanFtaFve immunoblopng analysis: Hippocampal Fssue was homogenized in protein lysis buffer. The membranes were probed with anFbodiesaginst GluN1 (1:750

Risk analysis to support operation and maintenance of an ageing dock-gate for the Port of Marseille Authority

The dry dock n°10 is a strategic infrastructure of the Port of Marseille Authority: its dimensions (465 x 85 m) place it among the biggest dry docks in Europe. Built in the seventies, it is isolated from the sea by a dock-gate in prestressed concrete. Faced to the ageing of this dock-gate, the Port of Marseille Authority wished to make the most of its knowledge in order to assess the feasibility of two considered operation scenarios: use the dry dock for ship repair or for building new civil engineering structures. In this context, OXAND and the Port of Marseille Authority worked together so as to obtain formal and objective decision-making indicators. These indicators took into account the different operation stakes of the dry dock (security, availability), the condition diagnosis and the ageing prognosis of components and facilities of the dock-gate, along with adapted maintenance actions and related costs. The risk analysis methodology used for this study allowed (1) to characterize the risks linked to each foreseen operation scenario, (2) to identify the most appropriate actions to control these risks, integrating operation constraints (e.g.: need to put the dock-gate in dry dock), (3) to rank these actions regarding their cost/benefit ratio and thus (4), to build a maintenance plan

MLE for the parameters of bivariate interval-valued models

With contemporary data sets becoming too large to analyze the data directly, various forms of aggregated data are becoming common. The original individual data are points, but after aggregation, the observations are interval-valued (e.g.). While some researchers simply analyze the set of averages of the observations by aggregated class, it is easily established that approach ignores much of the information in the original data set. The initial theoretical work for interval-valued data was that of Le-Rademacher and Billard (2011), but those results were limited to estimation of the mean and variance of a single variable only. This article seeks to redress the limitation of their work by deriving the maximum likelihood estimator for the all important covariance statistic, a basic requirement for numerous methodologies, such as regression, principal components, and canonical analyses. Asymptotic properties of the proposed estimators are established. The Le-Rademacher and Billard results emerge as special cases of our wider derivations.Comment: Will appear in ADA