6,495 research outputs found
The reaction 2H(p,pp)n in three kinematical configurations at E_p = 16 MeV
We measured the cross sections of the H(p,pp)n breakup reaction at
E=16 MeV in three kinematical configurations: the np final-state
interaction (FSI), the co-planar star (CST), and an intermediate-star (IST)
geometry. The cross sections are compared with theoretical predictions based on
the CD Bonn potential alone and combined with the updated 2-exchange
Tucson-Melbourne three-nucleon force (TM99'), calculated without inclusion of
the Coulomb interaction. The resulting excellent agreement between data and
pure CD Bonn predictions in the FSI testifies to the smallness of three-nucleon
force (3NF) effects as well as the insignificance of the Coulomb force for this
particular configuration and energy. The CST also agrees well whereas the IST
results show small deviations between measurements and theory seen before in
the pd breakup space-star geometries which point to possible Coulomb effects.
An additional comparison with EFT predictions (without 3NF) up to order NLO
shows excellent agreement in the FSI case and a rather similar agreement as for
CD Bonn in the CST and IST situations.Comment: 20 pages, 11 figure
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
The Polarized H and D Atomic Beam Source for ANKE at COSY-J\"ulich
A polarized atomic beam source was developed for the polarized internal
storage-cell gas target at the magnet spectrometer ANKE of COSY-J\"ulich. The
intensities of the beams injected into the storage cell, measured with a
compression tube, are hydrogen atoms/s (two hyperfine
states) and deuterium atoms/s (three hyperfine states). For
the hydrogen beam the achieved vector polarizations are . For the deuterium beam, the obtained combinations of vector
and tensor () polarizations are (with a
constant ), and or (both with vanishing ). The paper includes a detailed
technical description of the apparatus and of the investigations performed
during the development.Comment: 18 pages, 26 figures, 4 table
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 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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