122254340
SIMULATIONS OF MUON-INDUCED NEUTRON BACKGROUND WITH GEANT4
12512718
High-resolution X-ray spectroscopy and imaging of the nuclear outflow of the starburst galaxy NGC 253
Aims. Using XMM-Newton  data, we have studied the nuclear outflow of the nearby starburst galaxy NGC 253 in X-rays with respect to its morphology and to spectral variations along the outflow. Methods. We analysed XMM-Newton  RGS spectra, RGS brightness profiles in cross-dispersion direction, narrow-band RGS and EPIC images, and EPIC PN brightness profiles of the nuclear region and of the outflow from NGC 253. Results. We detect a diversity of emission lines along the outflow of NGC 253. This includes the He-like ions of Si, Mg, Ne, and O and their corresponding ions in the next higher ionisation state. Additionally transitions from $\ion{Fe}{xvii}$ and $\ion{Fe}{xviii}$ are prominent. The derived temperatures from line ratios along the outflow range from 0.21 ± 0.01 to 0.79 ± 0.06 keV, and the ratio of $\ion{Fe}{xvii}$ lines indicates a predominantly collisionally ionised plasma. Additionally, we see indications of either a recombining or an underionised plasma in the $\ion{Fe}{xvii}$ line ratio. Derived electron densities are 0.106 ± 0.018 cm -3 for the nuclear region and 0.025 ± 0.003 cm -3 for the outflow region closest to the centre. The RGS image in the $\ion{O}{viii}$ line energy clearly shows the morphology of an outflow extending out to ~750 pc along the southeast minor axis, while the northwest part of the outflow is not seen in $\ion{O}{viii}$ due to the heavy absorption by the galactic disc. This is the first time that the hot wind fluid has been detected directly. The limb brightening in Chandra  and XMM-Newton  EPIC observations is only seen in the energy range that contains the $\ion{Fe}{xvii}$ lines (550-750 eV). In all other energy ranges between 400 and 2000 eV, no clear evidence of limb brightening could be detected.
119283621
Results from 730 kg days of the CRESST-II Dark Matter search
The CRESST-II cryogenic Dark Matter search, aiming at detection of WIMPs via elastic scattering off nuclei in CaWO4 crystals, completed 730 kg days of data taking in 2011. We present the data collected with eight detector modules, each with a two-channel readout; one for a phonon signal and the other for coincidently produced scintillation light. The former provides a precise measure of the energy deposited by an interaction, and the ratio of scintillation light to deposited energy can be used to discriminate different types of interacting particles and thus to distinguish possible signal events from the dominant backgrounds.Sixty-seven events are found in the acceptance region where a WIMP signal in the form of low energy nuclear recoils would be expected. We estimate background contributions to this observation from four sources: (1) “leakage” from the e/γ-band (2) “leakage” from the α-particle band (3) neutrons and (4) 206Pb recoils from 210Po decay. Using a maximum likelihood analysis, we find, at a statistical significance of more than 4σ, that these sources alone are not sufficient to explain the data. The addition of a signal due to scattering of relatively light WIMPs could account for this discrepancy, and we determine the associated WIMP parameters.
122303611
The CRESST dark matter search
CRESST is a WIMP dark matter search using scintillating CaWO4 cryogenic detectors with active background suppression. First results obtained in the commissioning run are presented.
122869103
Evidence for Solar-Wind Charge-Exchange X-Ray Emission from the Earth’s Magnetosheath
122921889
SIMULATION OF LOW ENERGY NEUTRON RECOILS WITH GEANT4
123319980
Level-rank duality in nonunitary coset theories
It is shown that the conformal field theories SU(n)k*SU(n)1/SU(n)k+1 and SU(m)l*SU(m)1/SU(m)1+1 are equivalent, where k+n=n/m, l+m=m/n, for a pair (m, n) of relatively prime positive integers.
118577113
Real Time Imaging of Quantum and Thermal Fluctuations: The Case of a Two-Level System
A quantum system in contact with a heat bath undergoes quantum transitions between energy levels upon absorption or emission of energy quanta by the bath. These transitions remain virtual unless the energy of the system is measured repeatedly, even continuously in time. Isolating the two indispensable mechanisms in competition, we describe in a synthetic way the main physical features of thermally activated quantum jumps. Using classical tools of stochastic analysis, we compute in the case of a two-level system the complete statistics of jumps and transition times in the limit when the typical measurement time is small compared to the thermal relaxation time. The emerging picture is that quantum trajectories are similar to those of a classical particle in a noisy environment, subject to transitions à la Kramer in a multi-well landscape, but with a large multiplicative noise.
107502491
Bipolar monolithic preamplifiers for SSC silicon calorimetry
This paper describes preamplifiers designed specifically to address the requirements of silicon calorimetry for the Superconducting Super Collider (SSC). Eight different preamplifiers designed for detector capacitances ranging from 20 pF to 500 pF and operating temperatures from 25{degree}C to {minus}20{degree}C are discussed. The preamplifiers were fabricated with two different high-frequency processes (one with the VTC, Inc. VJ900 process, seven with the Harris Semiconductor VHF Process). The different topologies and their features are discussed in addition to the design methodologies employed. The results for noise, power consumption, speed, and radiation damage effects as well as data for post-damage annealing are presented for the VTC process preamplifier. Simulations for the VHF Process circuits are presented. This work was funded through SSC Generic Detector funding, SSC Detector Subsystem funding, and the Oak Ridge National Laboratory (ORNL) Detector Center.
59058647
COVARIANT DIFFERENTIAL EQUATIONS AND SINGULAR VECTORS IN VIRASORO REPRESENTATIONS
Abstract We give explicit expressions for the singular vectors in highest weight representations of the Virasoro algebra using a precise definition of fusion.
119268338
Light dark matter, naturalness, and the radiative origin of the electroweak scale
A bstractWe study classically scale invariant models in which the Standard Model Higgs mass term is replaced in the Lagrangian by a Higgs portal coupling to a complex scalar field of a dark sector. We focus on models that are weakly coupled with the quartic scalar couplings nearly vanishing at the Planck scale. The dark sector contains fermions and scalars charged under dark SU(2) × U(1) gauge interactions. Radiative breaking of the dark gauge group triggers electroweak symmetry breaking through the Higgs portal coupling. Requiring both a Higgs boson mass of 125.5 GeV and stability of the Higgs potential up to the Planck scale implies that the radiative breaking of the dark gauge group occurs at the TeV scale. We present a particular model which features a long-range abelian dark force. The dominant dark matter component is neutral dark fermions, with the correct thermal relic abundance, and in reach of future direct detection experiments. The model also has lighter stable dark fermions charged under the dark force, with observable effects on galactic-scale structure. Collider signatures include a dark sector scalar boson with mass ≲ 250 GeV that decays through mixing with the Higgs boson, and can be detected at the LHC. The Higgs boson, as well as the new scalar, may have significant invisible decays into dark sector particles.