We report results of a search for light (≲10 GeV) particle dark matter with the XENON10 detector. The event trigger was sensitive to a single electron, with the analysis threshold of 5 electrons ...corresponding to 1.4 keV nuclear recoil energy. Considering spin-independent dark matter-nucleon scattering, we exclude cross sections σ(n)>7×10(-42) cm(2), for a dark matter particle mass m(χ)=7 GeV. We find that our data strongly constrain recent elastic dark matter interpretations of excess low-energy events observed by CoGeNT and CRESST-II, as well as the DAMA annual modulation signal.
The XENON10 experiment at the Gran Sasso National Laboratory uses a 15 kg xenon dual phase time projection chamber to search for dark matter weakly interacting massive particles (WIMPs). The detector ...measures simultaneously the scintillation and the ionization produced by radiation in pure liquid xenon to discriminate signal from background down to 4.5 keV nuclear-recoil energy. A blind analysis of 58.6 live days of data, acquired between October 6, 2006, and February 14, 2007, and using a fiducial mass of 5.4 kg, excludes previously unexplored parameter space, setting a new 90% C.L. upper limit for the WIMP-nucleon spin-independent cross section of 8.8x10(-44) cm2 for a WIMP mass of 100 GeV/c2, and 4.5x10(-44) cm2 for a WIMP mass of 30 GeV/c2. This result further constrains predictions of supersymmetric models.
XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14
kg, was installed ...at the Gran Sasso Underground Laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulation data. The results on the detector’s energy threshold, position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10
keVr) and low background rate achieved.
We report a new determination of the strange quark contribution to the proton's magnetic form factor at a four-momentum transfer Q2=0.1 (GeV/c)2 from parity-violating e–p elastic scattering. The ...result uses a revised analysis of data from the SAMPLE experiment which was carried out at the MIT-Bates Laboratory. The data are combined with a calculation of the proton's axial form factor GeA to determine the strange form factor GsM(Q2=0.1)=0.37±0.20±0.26±0.07. The extrapolation of GsM to its Q2=0 limit and comparison with calculations is also discussed.
Although evidence documents the use of prestige and dominance for navigating group hierarchies, little is known about factors that explain people’s orientation toward prestige versus dominance. The ...current research applied a life history perspective to assess the role life history strategies play in prestige and dominance. Four studies document associations between adopting a slow life history strategy and having an orientation toward prestige. We also saw some (less consistent) evidence that people’s orientation toward prestige is rooted in exposure to predictable childhood environments, a known antecedent of slow life history strategies. Although we observed some evidence that exposure to unpredictable childhood environments was associated with dominance, there was little direct evidence that this relationship was explained by a fast life history strategy. Findings suggest that an orientation toward prestige is likely to be observed in people with a slow life history, who adopt a long-term time horizon for planning and decision-making.
Childhood unpredictability and harshness are associated with patterns of psychology and behavior that enable individuals to make the most of adverse environments. The current research assessed ...effects of childhood unpredictability and harshness on individual differences in sacrificial moral decision making. Six studies (N = 1,503) supported the hypothesis that childhood unpredictability, but not harshness, would be associated with fewer decisions to reject harm (consistent with deontological ethics) and to maximize overall outcomes (consistent with utilitarian ethics). These associations were not moderated by perceptions of current environmental unpredictability (Studies 3a and 3b) and were robust to potential confounds (religiosity, political conservativism, Big 5 personality traits, and social desirability; Study 5). The associations between childhood unpredictability and lower deontological and utilitarian tendencies were statistically mediated by low levels of empathic concern and poor-quality social relationships (Study 4). Findings are consistent with the possibility that early calibration to ecological unpredictability, but not harshness, undermines other-oriented psychological processes which, in turn, reduce moral concerns about harm and consequences for other people.
XENON10 is an experiment to directly detect weakly interacting massive particles (WIMPs), which may comprise the bulk of the nonbaryonic dark matter in our Universe. We report new results for ...spin-dependent WIMP-nucleon interactions with 129Xe and 131Xe from 58.6 live days of operation at the Laboratori Nazionali del Gran Sasso. Based on the nonobservation of a WIMP signal in 5.4 kg of fiducial liquid xenon mass, we exclude previously unexplored regions in the theoretically allowed parameter space for neutralinos. We also exclude a heavy Majorana neutrino with a mass in the range of approximately 10 GeV/c2-2 TeV/c2 as a dark matter candidate under standard assumptions for its density and distribution in the galactic halo.
A correlational pilot study (
= 143) and an integrative data analysis of two experiments (total
= 377) provide evidence linking anger to the psychology of social hierarchy. The experiments ...demonstrate that the experience of anger increases the psychological accessibility of implicit cognitions related to social hierarchy: compared to participants in a control condition, participants in an anger-priming condition completed word stems with significantly more hierarchy-related words. We found little support for sex differences in the effect of anger on implicit hierarchy-related cognition; effects were equivalent across male and female participants. Findings fit with functionalist evolutionary views of anger suggesting that anger may motivate the use of dominance to strive for high social rank in group hierarchies. Implications for downstream behaviour, including aggression and negotiation, are discussed.
Dominance and prestige are two strategies people use to regulate their social rank within group hierarchies. Despite a growing literature on dominance- and prestige-oriented leaders, little is known ...about how those strategies operate among people lower in social rank. Four studies tested the hypothesis that, among subordinates, dominance and prestige are associated with high levels of malicious and benign envy, respectively. Individual differences in prestige were positively and independently associated with benign envy, and negatively associated with malicious envy. Individual differences in dominance were positively and independently associated with both malicious and benign envy. Two experiments demonstrated that activating a prestige-oriented mindset (relative to a dominance-oriented mindset) caused people to display higher levels of benign envy. No experimental effects on malicious envy were observed. Theories of prestige and dominance provide a useful framework for understanding ways in which subordinate group members strive for high social rank.
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