Search results for "Background"
showing 10 items of 556 documents
Phase joint transform sequential correlator for nonlinear binary correlations
2005
We study the performance of nonlinear optical correlations using a joint transform correlator that operates in phase-only spatial light modulation at input joint transform plane. Amplitude input nonlinear optical time sequential correlations have shown better discrimination and noise robustness than conventional linear correlations. Those nonlinear correlations are based on decomposing the reference and the target into binary slices and to add the contribution of all linear correlations between them. Those correlations can be easily implemented using a conventional joint transform correlator. However, the system has poor efficiency and low cross-correlation peak intensity, mainly because of…
Preliminary assessment of the ATHENA/WFI non-X-ray background
2017
We present a preliminary assessment of the non-X-ray background for the WFI on board ATHENA conducted at IAAT in the context of the collaborative background and radiation damage working group activities. Our main result is that in the baseline configuration originally assumed for the camera the requirement on the level of non-X-ray background could not be met. In light of the results of Geant4 simulations we propose and discuss a possible optimization of the camera design and pinpoint some open issues to be addressed in the next phase of investigation. One of these concerns the possible contribution to the non-X-ray background from soft protons and ions funneled to the focal plane through t…
Searches for neutrinoless resonant double electron captures at LNGS
2012
Several experiments were performed during last years at underground (3600 m w.e.) Laboratori Nazionali del Gran Sasso (LNGS) of the INFN (Italy) to search for resonant 2$\varepsilon0\nu$ captures in 96Ru, 106Cd, 136Ce, 156Dy, 158Dy, 180W, 184Os, 190Pt with the help of HP Ge semiconductor detectors, and ZnWO4 and 106CdWO4 crystal scintillators. No evidence for r-2$\varepsilon0\nu$ decays was found, and only T_{1/2} limits were established in the range of 10^{14}-10^{21} yr.
Large-scale inhomogeneities may improve the cosmic concordance of supernovae
2010
We reanalyze the supernovae data from the Union Compilation including the weak lensing effects caused by inhomogeneities. We compute the lensing probability distribution function for each background solution described by the parameters Omega_M, Omega_L and w in the presence of inhomogeneities, approximately modeled with a single-mass population of halos. We then perform a likelihood analysis in the space of FLRW-parameters and compare our results with the standard approach. We find that the inclusion of lensing can move the best-fit model significantly towards the cosmic concordance of the flat LCDM model, improving the agreement with the constraints coming from the cosmic microwave backgro…
A self-consistent approach to the reflection component in 4U 1705-44
2010
High-resolution spectroscopy has recently revealed in many neutron-star Low-Mass X-ray binaries that the shape of the broad iron line observed in the 6.4-6.97 keV range is consistently well fitted by a relativistically smeared line profile. We show here spectral fitting results using a newly developed self-consistent reflection model on XMM-Newton data of the LMXB 4U 1705-44 during a period when the source was in a bright soft state. This reflection model adopts a blackbody prescription for the shape of the impinging radiation field, that we physically associate with the boundary layer emission. © 2010 American Institute of Physics.
Background Simulations of the Wide Field Imager of the ATHENA X-Ray Observatory
2011
The ATHENA X-ray Observatory-IXO is a planned multinational orbiting X-ray observatory with a focal length of 11.5m. ATHENA aims to perform pointed observations in an energy range from 0.1 keV to 15 keV with high sensitivity. For high spatial and timing resolution imaging and spectroscopic observations the 640x640 pixel^2 large DePFET-technology based Wide field Imager (WFI) focal plane detector, providing a field of view of 18 arcsec will be the main detector. Based on the actual mechanics, thermal and shielding design we present estimates for the WFI cosmic ray induced background obtained by the use of Monte-Carlo simulations and possible background reduction measures.
IceCube: A multipurpose neutrino telescope
2008
IceCube is a new high-energy neutrino telescope which will be coming online in the near future. IceCube will be capable of measuring fluxes of all three flavors of neutrino, and its peak neutrino energy sensitivity will be in the TeV–PeV range. Here, after a brief description of the detector, we describe its anticipated performance with a selection of physics topics: supernovae, extraterrestrial diffuse and point sources of neutrinos, gamma-ray bursts, neutrinos from WIMP annihilation, and cosmic ray composition.
A measurement of material in the ATLAS tracker using secondary hadronic interactions in 7 TeV pp collisions
2016
Knowledge of the material in the ATLAS inner tracking detector is crucial in understanding the reconstruction of charged-particle tracks, the performance of algorithms that identify jets containing b-hadrons and is also essential to reduce background in searches for exotic particles that can decay within the inner detector volume. Interactions of primary hadrons produced in pp collisions with the material in the inner detector are used to map the location and amount of this material. The hadronic interactions of primary particles may result in secondary vertices, which in this analysis are reconstructed by an inclusive vertex-finding algorithm. Data were collected using minimum-bias trigger…
Long-lived particles at the energy frontier: the MATHUSLA physics case
2019
We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of Standard Model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the $\mu$m scale up to the Big Bang Nucleosynthesis limit of $\sim 10^7$m. Neutral LLPs with lifetimes above $\sim$ 100m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging …
Search for point-like sources of ultra-high energy neutrinos at the pierre auger observatory and improved limit on the diffuse flux of tau neutrinos
2012
The surface detector array of the Pierre Auger Observatory can detect neutrinos with energy Eν between 1017 eV and 1020 eV from point-like sources across the sky south of +55º and north of −65º declinations. A search has been performed for highly inclined extensive air showers produced by the interaction of neutrinos of all flavors in the atmosphere (downward-going neutrinos), and by the decay of tau leptons originating from tau neutrino interactions in Earth’s crust (Earth-skimming neutrinos). No candidate neutrinos have been found in data up to 2010 May 31. This corresponds to an equivalent exposure of ∼3.5 years of a full surface detector array for the Earth-skimming channel and ∼2 years…