550 research outputs found
The -cleus experiment: A gram-scale fiducial-volume cryogenic detector for the first detection of coherent neutrino-nucleus scattering
We discuss a small-scale experiment, called -cleus, for the first
detection of coherent neutrino-nucleus scattering by probing nuclear-recoil
energies down to the 10 eV-regime. The detector consists of low-threshold
CaWO and AlO calorimeter arrays with a total mass of about 10 g and
several cryogenic veto detectors operated at millikelvin temperatures.
Realizing a fiducial volume and a multi-element target, the detector enables
active discrimination of , neutron and surface backgrounds. A first
prototype AlO device, operated above ground in a setup without
shielding, has achieved an energy threshold of eV and further
improvements are in reach. A sensitivity study for the detection of coherent
neutrino scattering at nuclear power plants shows a unique discovery potential
(5) within a measuring time of weeks. Furthermore, a site
at a thermal research reactor and the use of a radioactive neutrino source are
investigated. With this technology, real-time monitoring of nuclear power
plants is feasible.Comment: 14 pages, 19 figure
Black hole masses and starbursts in X-shaped radio sources
It has been suggested that the X-shaped morphology observed in some radio
sources can reflect either a recent merger of two supermassive black holes
(SMBHs) or the presence of a second active black hole in the galactic nucleus.
These scenarios are tested by studying the relationship between the black hole
mass, radio and optical luminosity, starburst history, and dynamic age of radio
lobes in a sample of 29 X-shaped radio galaxies drawn from a list of 100
X-shaped radio source candidates identified from the FIRST survey. The same
relationships are also studied in a control sample consisting of 36 radio-loud
active nuclei with similar redshifts and optical and radio luminosities. The
X-shaped objects are found to have statistically higher black hole masses and
older starburst activity compared to the objects from the control sample.
Implications of these findings are discussed for the black hole merger scenario
and for the potential presence of active secondary black holes in post-merger
galaxies.Comment: 11 pages, 8 figure
Verliebt – Verlobt – Verheiratet:Wandel der Hochzeit im 20. Jahrhundert
Die Entscheidung zu heiraten gilt heute als höchstpersönliche Angelegenheit des Brautpaares und Grundstein ihres individuellen Glücks. Doch wenn ein Paar heiratet, ist das nicht nur eine private Entscheidung. Die Brautleute sind immer auch Einflüssen aus Elternhaus, Kirche, Gesamtgesellschaft und Staat ausgesetzt und wirken ihrerseits mit ihrer Entscheidung auf diese Institutionen zurück. Änderungen im Heiratsverhalten stellen somit einen wichtigen Indikator für gesellschaftliche Entwicklungen dar. Um diese Entwicklungen erfassen und darstellen zu können, hat eine Gruppe von acht Teilnehmerinnen und Teilnehmern des Studiums im Alter an der Universität Münster, die Geschichte der Hochzeit im 20. Jahrhundert im Vergleich der Hochzeitsgenerationen der Studierenden (Heirat 1960-75), ihrer Eltern (Heirat 1930-45) und Großeltern (Heirat 1900-1915) untersucht. Hierzu recherchierte die Gruppe in Archiven und Bibliotheken und wertete 586 für das Projekt entwickelte, standardisierte Fragebögen aus
Dark-Photon Search using Data from CRESST-II Phase 2
Identifying the nature and origin of dark matter is one of the major
challenges for modern astro and particle physics. Direct dark-matter searches
aim at an observation of dark-matter particles interacting within detectors.
The focus of several such searches is on interactions with nuclei as provided
e.g. by Weakly Interacting Massive Particles. However, there is a variety of
dark-matter candidates favoring interactions with electrons rather than with
nuclei. One example are dark photons, i.e., long-lived vector particles with a
kinetic mixing to standard-model photons. In this work we present constraints
on this kinetic mixing based on data from CRESST-II Phase 2 corresponding to an
exposure before cuts of 52\,kg-days. These constraints improve the existing
ones for dark-photon masses between 0.3 and 0.7\,keV/c.Comment: submitted EPJ
Results on light dark matter particles with a low-threshold CRESST-II detector
The CRESST-II experiment uses cryogenic detectors to search for nuclear
recoil events induced by the elastic scattering of dark matter particles in
CaWO crystals. Given the low energy threshold of our detectors in
combination with light target nuclei, low mass dark matter particles can be
probed with high sensitivity. In this letter we present the results from data
of a single detector module corresponding to 52 kg live days. A blind analysis
is carried out. With an energy threshold for nuclear recoils of 307 eV we
substantially enhance the sensitivity for light dark matter. Thereby, we extend
the reach of direct dark matter experiments to the sub-region and demonstrate
that the energy threshold is the key parameter in the search for low mass dark
matter particles.Comment: 8 pages, 8 figure
Results on MeV-scale dark matter from a gram-scale cryogenic calorimeter operated above ground
Models for light dark matter particles with masses below 1 GeV/c are a
natural and well-motivated alternative to so-far unobserved weakly interacting
massive particles. Gram-scale cryogenic calorimeters provide the required
detector performance to detect these particles and extend the direct dark
matter search program of CRESST. A prototype 0.5 g sapphire detector developed
for the -cleus experiment has achieved an energy threshold of
eV, which is one order of magnitude lower than previous
results and independent of the type of particle interaction. The result
presented here is obtained in a setup above ground without significant
shielding against ambient and cosmogenic radiation. Although operated in a
high-background environment, the detector probes a new range of light-mass dark
matter particles previously not accessible by direct searches. We report the
first limit on the spin-independent dark matter particle-nucleon cross section
for masses between 140 MeV/c and 500 MeV/c.Comment: 6 pages, 6 figures, v3: ancillary files added, v4: high energy
spectrum (0.6-12keV) added to ancillary file
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