967 research outputs found
Improving Engagement and Well-being Through Strengths and Career-Focused Programming in the Living Learning Community
This study evaluates self-reported well-being and engagement of learning community students who receive strengths and career-focused programming and compares them to a control group of freshman students
Monte Carlo aided design of the inner muon veto detectors for the Double Chooz experiment
The Double Chooz neutrino experiment aims to measure the last unknown
neutrino mixing angle theta_13 using two identical detectors positioned at
sites both near and far from the reactor cores of the Chooz nuclear power
plant. To suppress correlated background induced by cosmic muons in the
detectors, they are protected by veto detector systems. One of these systems is
the inner muon veto. It is an active liquid scintillator based detector and
instrumented with encapsulated photomultiplier tubes. In this paper we describe
the Monte Carlo aided design process of the inner muon veto, that resulted in a
detector configuration with 78 PMTs yielding an efficiency of 99.978 +- 0.004%
for rejecting muon events and an efficiency of >98.98% for rejecting correlated
events induced by muons. A veto detector of this design is currently used at
the far detector site and will be built and incorporated as the muon
identification system at the near site of the Double Chooz experiment
Dynamics and Energy Distribution of Non-Equilibrium Quasiparticles in Superconducting Tunnel Junctions
We present a full theoretical and experimental study of the dynamics and
energy distribution of non-equilibrium quasiparticles in superconducting tunnel
junctions (STJs). STJs are often used for single-photon spectrometers, where
the numbers of quasiparticles excited by a photon provide a measure of the
photon energy. The magnitude and fluctuations of the signal current in STJ
detectors are in large part determined by the quasiparticle dynamics and energy
distribution during the detection process. We use this as motivation to study
the transport and energy distribution of non-equilibrium quasiparticles excited
by x-ray photons in a lateral, imaging junction configuration. We present a
full numerical model for the tunneling current of the major physical processes
which determine the signal. We find that a diffusion framework models the
quasiparticle dynamics well and that excited quasiparticles do not equilibrate
to the lattice temperature during the timescales for tunneling. We extract
physical timescales from the measured data, make comparisons with existing
theories, and comment on implications for superconducting mesoscopic systems
and single-photon detectors.Comment: 25 pages text, 15 figure
The CRESST Dark Matter Search
We present first competitive results on WIMP dark matter using the
phonon-light-detection technique. A particularly strong limit for WIMPs with
coherent scattering results from selecting a region of the phonon-light plane
corresponding to tungsten recoils. The observed count rate in the neutron band
is compatible with the rate expected from neutron background. CRESST is
presently being upgraded with a 66 channel SQUID readout system, a neutron
shield and a muon veto system. This results in a significant improvement in
sensitivity.Comment: 6 pages, 3 figures, to be published in the proceedings of the 5th
International Workshop on the Identification and Detection of Dark Matter IDM
2004, Edinburgh, Sept. 2004, World Scientifi
The CRESST Dark Matter Search
The current status of CRESST (Cryogenic Rare Event Search using
Superconducting Thermometers) and new results concerning the detector
development are presented. The basic technique of CRESST is to search for
particle Dark Matter (WIMPS, Weakly Interacting Massive particles) by the
measurement of non-thermal phonons as created by WIMP-induced nuclear recoils.
Combined with the newly developed method of simultaneous measurement of
scintillation light, strong background discrimination is possible, resulting in
a substantial increase in WIMP detection sensitivity. The short and long term
perspectives of CRESST are discussed.Comment: 12 pages, 6 figure
Frontotemporal dementia, music perception and social cognition share neurobiological circuits:A meta-analysis
Frontotemporal dementia (FTD) is a neurodegenerative disease that presents with profound changes in social cognition. Music might be a sensitive probe for social cognition abilities, but underlying neurobiological substrates are unclear. We performed a meta-analysis of voxel-based morphometry studies in FTD patients and functional MRI studies for music perception and social cognition tasks in cognitively normal controls to identify robust patterns of atrophy (FTD) or activation (music perception or social cognition). Conjunction analyses were performed to identify overlapping brain regions. In total 303 articles were included: 53 for FTD (n = 1153 patients, 42.5% female; 1337 controls, 53.8% female), 28 for music perception (n = 540, 51.8% female) and 222 for social cognition in controls (n = 5664, 50.2% female). We observed considerable overlap in atrophy patterns associated with FTD, and functional activation associated with music perception and social cognition, mostly encompassing the ventral language network. We further observed overlap across all three modalities in mesolimbic, basal forebrain and striatal regions. The results of our meta-analysis suggest that music perception and social cognition share neurobiological circuits that are affected in FTD. This supports the idea that music might be a sensitive probe for social cognition abilities with implications for diagnosis and monitoring
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