We present results of a dark matter search performed with a 0.6 kg d exposure of the DAMIC experiment at the SNOLAB underground laboratory. We measure the energy spectrum of ionization events in the ...bulk silicon of charge-coupled devices down to a signal of 60 eV electron equivalent. The data are consistent with radiogenic backgrounds, and constraints on the spin-independent WIMP-nucleon elastic-scattering cross section are accordingly placed. A region of parameter space relevant to the potential signal from the CDMS-II Si experiment is excluded using the same target for the first time. This result obtained with a limited exposure demonstrates the potential to explore the low-mass WIMP region (<10 GeV c−2) with the upcoming DAMIC100, a 100 g detector currently being installed in SNOLAB.
We used Spitzer Space Telescope 3.6, 8.0, 70 and 160 μm data, James Clerk Maxwell Telescope HARP-B CO J= (3–2) data, National Radio Astronomy Observatory 12 m telescope CO J= (1–0) data and Very ...Large Array H i data to investigate the relations among polycyclic aromatic hydrocarbons (PAHs), cold (∼20 K) dust, molecular gas and atomic gas within NGC 2403, an SABcd galaxy at a distance of 3.13 Mpc. The dust surface density is mainly a function of the total (atomic and molecular) gas surface density and galactocentric radius. The gas-to-dust ratio monotonically increases with radius, varying from ∼100 in the nucleus to ∼400 at 5.5 kpc. The slope of the gas-to-dust ratio is close to that of the oxygen abundance, suggesting that metallicity strongly affects the gas-to-dust ratio within this galaxy. The exponential scale length of the radial profile for the CO J= (3–2) emission is statistically identical to the scale length for the stellar continuum-subtracted 8 μm (PAH 8 μm) emission. However, CO J= (3–2) and PAH 8 μm surface brightnesses appear uncorrelated when examining sub-kpc-sized regions.
The CONNIE experiment Aguilar-Arevalo, A.; Bertou, X.; Bonifazi, C. ...
Journal of physics. Conference series,
10/2016, Letnik:
761, Številka:
1
Journal Article
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The CONNIE experiment uses fully depleted, high resistivity CCDs as particle detectors in an attempt to measure for the first time the Coherent Neutrino-Nucleus Elastic Scattering of antineutrinos ...from a nuclear reactor with silicon nuclei. This talk, given at the XV Mexican Workshop on Particles and Fields (MWPF), discussed the potential of CONNIE to perform this measurement, the installation progress at the Angra dos Reis nuclear power plant, as well as the plans for future upgrades.
The CONNIE detector prototype is operating at a distance of 30 m from the core of a 3.8 GW sub(th) nuclear reactor with the goal of establishing Charge-Coupled Devices (CCD) as a new technology for ...the detection of coherent elastic neutrino-nucleus scattering. We report on the results of the engineering run with an active mass of 4 g of silicon. The CCD array is described, and the performance observed during the first year is discussed. A compact passive shield was deployed around the detector, producing an order of magnitude reduction in the background rate. The remaining background observed during the run was stable, and dominated by internal contamination in the detector packaging materials. The in-situ calibration of the detector using X-ray lines from fluorescence demonstrates good stability of the readout system. The event rates with the reactor ON and OFF are compared, and no excess is observed coming from nuclear fission at the power plant. The upper limit for the neutrino event rate is set two orders of magnitude above the expectations for the standard model. The results demonstrate the cryogenic CCD-based detector can be remotely operated at the reactor site with stable noise below 2 e super(-) RMS and stable background rates. The success of the engineering test provides a clear path for the upgraded 100 g detector to be deployed during 2016.
An analysis of large-area CO J= 3-2 maps from the James Clerk Maxwell Telescope for 12 nearby spiral galaxies reveals low velocity dispersions in the molecular component of the interstellar medium. ...The three lowest luminosity galaxies show a relatively flat velocity dispersion as a function of radius while the remaining nine galaxies show a central peak with a radial fall-off within 0.2-0.4r
25. Correcting for the average contribution due to the internal velocity dispersions of a population of giant molecular clouds, the average cloud-cloud velocity dispersion across the galactic discs is 6.1 ± 1.0 km s−1 (standard deviation of 2.9 km s−1), in reasonable agreement with previous measurements for the Galaxy and M33. The cloud-cloud velocity dispersion derived from the CO data is on average two times smaller than the H i velocity dispersion measured in the same galaxies. The low cloud-cloud velocity dispersion implies that the molecular gas is the critical component determining the stability of the galactic disc against gravitational collapse, especially in those regions of the disc which are H2 dominated. The cloud-cloud velocity dispersion shows a significant positive correlation with both the far-infrared luminosity, which traces the star formation activity, and the K-band absolute magnitude, which traces the total stellar mass. For three galaxies in the Virgo cluster, smoothing the data to a resolution of 4.5 kpc (to match the typical resolution of high-redshift CO observations) increases the measured velocity dispersion by roughly a factor of 2, comparable to the dispersion measured recently in a normal galaxy at z= 1. This comparison suggests that the mass and star formation rate surface densities may be similar in galaxies from z= 0 to 1 and that the high star formation rates seen at z= 1 may be partly due to the presence of physically larger molecular gas discs.
The Gould Belt Legacy Survey on the James Clerk Maxwell Telescope's has observed a region of 260 arcmin2 in 12CO J= 3 → 2 emission, and a 190 arcmin2 subset of this in 13CO and C18O towards the ...Serpens molecular cloud. We examine the global velocity structure of the non-outflowing gas, and calculate excitation temperatures and opacities. The large-scale mass and energetics of the region are evaluated, with special consideration for high-velocity gas. We find the cloud to have a mass of 203 M⊙, and to be gravitationally bound, and that the kinetic energy of the outflowing gas is approximately 70 per cent of the turbulent kinetic energy of the cloud. We identify compact outflows towards some of the submillimetre Class 0/I sources in the region.
Abstract
We present the first data release of the James Clerk Maxwell Telescope Plane Survey (JPS), the JPS Public Release 1. JPS is an 850-μm continuum survey of six fields in the northern inner ...Galactic plane in a longitude range of ℓ = 7°–63°, made with the Submillimetre Common-User Bolometer Array 2. This first data release consists of emission maps of the six JPS regions with an average pixel-to-pixel noise of 7.19 mJy beam−1, when smoothed over the beam, and a compact source catalogue containing 7813 sources. The 95 per cent completeness limits of the catalogue are estimated at 0.04 Jy beam−1 and 0.3 Jy for the peak and integrated flux densities, respectively. The emission contained in the compact source catalogue is 42 ± 5 per cent of the total and, apart from the large-scale (greater than 8 arcmin) emission, there is excellent correspondence with features in the 500-μm Herschel maps. We find that, with two-dimensional matching, 98 ± 2 per cent of sources within the fields centred at ℓ = 20°, 30°, 40° and 50° are associated with molecular clouds, with 91 ± 3 per cent of the ℓ = 30° and 40° sources associated with dense molecular clumps. Matching the JPS catalogue to Herschel 70-μm sources, we find that 38 ± 1 per cent of sources show evidence of ongoing star formation. The JPS Public Release 1 images and catalogue will be a valuable resource for studies of star formation in the Galaxy and the role of environment and spiral arms in the star formation process.
The CONNIE Experiment (Coherent Neutrino Nucleus Interaction Experiment) is currently collecting reactor neutrino data to search for the undiscovered standard model process of coherent ...neutrino-nucleus scattering (CNNS). The detector is composed of a silicon target of thick, fully-depleted, low-noise CCD detectors. Results from data collected in 2015 indicate backgrounds are controlled, and allow an estimate of sensitivity to be presented for a larger scale detector. A 2016 upgrade, adding additional target mass, and reducing readout noise, has been performed, increasing the total yield of signal events by a factor of 30, and already yielding science-quality data. Low-energy nuclear calibrations have been performed, enabling calibration down to the device energy threshold. An estimate of the sensitivity expected for measuring the coherent neutrino process is presented. Future prospects with improved detector energy thresholds are estimated.
ABSTRACT We have investigated the physical properties of Planck Galactic Cold Clumps (PGCCs) located in the Galactic Plane, using the JCMT Plane Survey (JPS) and the SCUBA-2 Continuum Observations of ...Pre-protostellar Evolution (SCOPE) survey. By utilizing a suite of molecular-line surveys, velocities, and distances were assigned to the compact sources within the PGCCs, placing them in a Galactic context. The properties of these compact sources show no large-scale variations with Galactic environment. Investigating the star-forming content of the sample, we find that the luminosity-to-mass ratio (L/M) is an order of magnitude lower than in other Galactic studies, indicating that these objects are hosting lower levels of star formation. Finally, by comparing ATLASGAL sources that are associated or are not associated with PGCCs, we find that those associated with PGCCs are typically colder, denser, and have a lower L/M ratio, hinting that PGCCs are a distinct population of Galactic Plane sources.
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