1,768 research outputs found
Identification of photons in double beta-decay experiments using segmented germanium detectors - studies with a GERDA Phase II prototype detector
The sensitivity of experiments searching for neutrinoless double beta-decay
of germanium was so far limited by the background induced by external
gamma-radiation. Segmented germanium detectors can be used to identify photons
and thus reduce this background component.
The GERmanium Detector Array, GERDA, will use highly segmented germanium
detectors in its second phase. The identification of photonic events is
investigated using a prototype detector. The results are compared with Monte
Carlo data.Comment: 20 pages, 7 figures, to be submitted to NIM-
Pulse shape simulation for segmented true-coaxial HPGe detectors
A new package to simulate the formation of electrical pulses in segmented
true-coaxial high purity germanium detectors is presented. The computation of
the electric field and weighting potentials inside the detector as well as of
the trajectories of the charge carriers is described. In addition, the
treatment of bandwidth limitations and noise are discussed. Comparison of
simulated to measured pulses, obtained from an 18-fold segmented detector
operated inside a cryogenic test facility, are presented.Comment: 20 pages, 16 figure
Axes determination for segmented true-coaxial HPGe detectors
A fast method to determine the crystallographic axes of segmented
true-coaxial high-purity germanium detectors is presented. It is based on the
analysis of segment-occupancy patterns obtained by irradiation with radioactive
sources. The measured patterns are compared to predictions for different axes
orientations. The predictions require a simulation of the trajectories of the
charge carriers taking the transverse anisotropy of their drift into account.Comment: 18 pages, 1 table, 31 figures; included background contribution to
the occupancy patterns and systematic uncertainties, results slightly change
Investigation into the limits of perturbation theory at low Q^2 using HERA deep inelastic scattering data
A phenomenological study of the final combined HERA data on inclusive deep
inelastic scattering (DIS) has been performed. The data are presented and
investigated for a kinematic range extending from values of the four-momentum
transfer, , above 10 GeV down to the lowest values observable at
HERA of = 0.045 GeV and Bjorken , = 6
10. The data are well described by fits based on perturbative quantum
chromodynamics (QCD) using collinear factorisation and evolution of the parton
densities encompassed in the DGLAP formalism from the highest down to
of a few GeV. The Regge formalism can describe the data up to 0.65 GeV. The complete data set can be described by a new fit
using the ALLM parameterisation. The region between the Regge and the
perturbative QCD regimes is of particular interest.Comment: 38 pages, 13 figure
Characterization of the first true coaxial 18-fold segmented n-type prototype detector for the GERDA project
The first true coaxial 18-fold segmented n-type HPGe prototype detector
produced by Canberra-France for the GERDA neutrinoless double beta-decay
project was tested both at Canberra-France and at the Max-Planck-Institut fuer
Physik in Munich. The main characteristics of the detector are given and
measurements concerning detector properties are described. A novel method to
establish contacts between the crystal and a Kapton cable is presented.Comment: 21 pages, 16 Figures, to be submitted to NIM
The GALATEA Test-Facility for High Purity Germanium Detectors
GALATEA is a test facility designed to investigate bulk and surface effects
in high purity germanium detectors. A vacuum tank houses an infrared screened
volume with a cooled detector inside. A system of three stages allows an almost
complete scan of the detector. The main feature of GALATEA is that there is no
material between source and detector. This allows the usage of alpha and beta
sources as well as of a laser beam to study surface effects. A 19-fold
segmented true-coaxial germanium detector was used for commissioning
Speckle Interferometry of Metal-Poor Stars in the Solar Neighborhood. I
We report the results of speckle-interferometric observations of 109 high
proper-motion metal-poor stars made with the 6-m telescope of the Special
Astrophysical Observatory of the Russian Academy of Sciences. We resolve eight
objects -- G102-20, G191-55, BD+19~1185A, G89-14, G87-45, G87-47,
G111-38, and G114-25 -- into individual components and we are the first to
astrometrically resolve seven of these stars. New resolved systems included two
triple (G111-38, G87-47) and one quadruple (G89-14) star. The ratio of
single-to-binary-to-triple-to-quadruple systems among the stars of our sample
is equal to 71:28:6:1.Comment: 8 pages, 4 figures, accepted to Astrophysical Bulleti
Measurement of the temperature dependence of pulse lengths in an n-type germanium detector
The temperature dependence of the pulse length was measured for an 18-fold
segmented n-type germanium detector in the temperature range of 77-120 K. The
interactions of 122 keV photons originating from a Europium-152 source were
selected and pulses as observed on the core and segment electrodes were
studied. In both cases, the temperature dependence can be well described by a
Boltzmann-like ansatz.Comment: 17 pages, 2 tables, 13 figures, published in EPJ A
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