63 research outputs found
Spectral Signature Analysis – BIST for RF Front-Ends
In this paper, the Spectral Signature Analysis is presented as a concept for an integrable self-test system (Built-In Self-Test – BIST) for RF front-ends is presented. It is based on modelling the whole RF front-end (transmitter and receiver) on system level, on generating of a Spectral Signature and of evaluating of the Signature Response. Because of using multi-carrier signal as the test signature, the concept is especially useful for tests of linearity and frequency response of front-ends. Due to the presented method of signature response evaluation, this concept can be used for Built-In Self-Correction (BISC) at critical building blocks
Precision Measurement of the 29Si, 33S, and 36Cl Binding Energies
The binding energies of 29Si, 33S, and 36Cl have been measured with a
relative uncertainty using a flat-crystal spectrometer.
The unique features of these measurements are 1) nearly perfect crystals whose
lattice spacing is known in meters, 2) a highly precise angle scale that is
derived from first principles, and 3) a gamma-ray measurement facility that is
coupled to a high flux reactor with near-core source capability. The binding
energy is obtained by measuring all gamma-rays in a cascade scheme connecting
the capture and ground states. The measurements require the extension of
precision flat-crystal diffraction techniques to the 5 to 6 MeV energy region,
a significant precision measurement challenge. The binding energies determined
from these gamma-ray measurements are consistent with recent highly accurate
atomic mass measurements within a relative uncertainty of .
The gamma-ray measurement uncertainties are the dominant contributors to the
uncertainty of this consistency test. The measured gamma-ray energies are in
agreement with earlier precision gamma-ray measurements.Comment: 13 pages, 4 figure
R&D progress on second-generation crystals for Laue lens applications
The concept of a gamma-ray telescope based on a Laue lens offers the
possibility to increase the sensitivity by more than an order of magnitude with
respect to existing instruments. Laue lenses have been developed by our
collaboration for several years : the main achievement of this R&D program was
the CLAIRE lens prototype. Since then, the endeavour has been oriented towards
the development of efficient diffracting elements (crystal slabs), the aim
being to step from a technological Laue lens to a scientifically exploitable
lens. The latest mission concept featuring a gamma-ray lens is the European
Gamma-Ray Imager (GRI) which intends to make use of the Laue lens to cover
energies from 200 keV to 1300 keV.
Investigations of two promising materials, low mosaicity copper and gradient
concentration silicon-germanium are presented in this paper. The measurements
have been performed during three runs on beamline ID15A of the European
Synchrotron Radiation Facility, and on the GAMS 4 instrument of the Institute
Laue-Langevin (both in Grenoble, France) using highly monochromatic beam of
energy close to 500 keV. Despite it was not perfectly homogeneous, the
presented copper crystal exhibits peak reflectivity of 25% in accordance with
theoretical predictions, and a mosaicity around 26 arcsec, the ideal range for
the realization of a Laue lens such as GRI. Silicon-germanium featuring a
constant gradient have been measured for the very first time at 500 keV. Two
samples showed a quite homogeneous reflectivity reaching 26%, which is far from
the 48% already observed in experimental crystals but a very encouraging
beginning. This results have been used to estimate the performance of the GRI
Laue lens design
The (n, gamma) campaigns at EXILL
At the PF1B cold neutron beam line at the Institut Laue Langevin, the EXILL array consisting of EXOGAM, GASP and ILL-Clover detectors was used to perform (n, gamma) measurements at very high coincidence rates. About ten different reactions were measured in autumn 2012 using a highly collimated cold neutron beam. In spring 2013, the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the EXILL&FATIMA campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of the set-ups and present first results from both campaigns
The neutron and its role in cosmology and particle physics
Experiments with cold and ultracold neutrons have reached a level of
precision such that problems far beyond the scale of the present Standard Model
of particle physics become accessible to experimental investigation. Due to the
close links between particle physics and cosmology, these studies also permit a
deep look into the very first instances of our universe. First addressed in
this article, both in theory and experiment, is the problem of baryogenesis ...
The question how baryogenesis could have happened is open to experimental
tests, and it turns out that this problem can be curbed by the very stringent
limits on an electric dipole moment of the neutron, a quantity that also has
deep implications for particle physics. Then we discuss the recent spectacular
observation of neutron quantization in the earth's gravitational field and of
resonance transitions between such gravitational energy states. These
measurements, together with new evaluations of neutron scattering data, set new
constraints on deviations from Newton's gravitational law at the picometer
scale. Such deviations are predicted in modern theories with extra-dimensions
that propose unification of the Planck scale with the scale of the Standard
Model ... Another main topic is the weak-interaction parameters in various
fields of physics and astrophysics that must all be derived from measured
neutron decay data. Up to now, about 10 different neutron decay observables
have been measured, much more than needed in the electroweak Standard Model.
This allows various precise tests for new physics beyond the Standard Model,
competing with or surpassing similar tests at high-energy. The review ends with
a discussion of neutron and nuclear data required in the synthesis of the
elements during the "first three minutes" and later on in stellar
nucleosynthesis.Comment: 91 pages, 30 figures, accepted by Reviews of Modern Physic
Abrupt shape transition at neutron number N=60: B(E2) values in 94,96,98Sr from fast g-g timing
International audienceLifetimes of low-lying yrast states in neutron-rich 94,96,98Sr have been measured by Germanium-gated γ−γ fast timing with LaBr3(Ce) detectors using the EXILL&FATIMA spectrometer at the Institut Laue-Langevin. Sr fission products were generated using cold-neutron-induced fission of 235U and stopped almost instantaneously within the thick target. The experimental B(E2) values are compared with results of Monte Carlo shell-model calculations made without truncation on the occupation numbers of the orbits spanned by eight proton and eight neutron orbits and show good agreement. Similarly to the Zr isotopes, the abrupt shape transition in the Sr isotopes near neutron number N=60 is identified as being caused by many-proton excitations to its g9/2 orbit
Experimental study of the lifetime and phase transition in neutron-rich <sup>98,100,102</sup>Zr
International audienceRapid shape changes are observed for neutron-rich nuclei with A around 100. In particular, a sudden onset of ground-state deformation is observed in the Zr and Sr isotopic chains at N = 60: Low-lying states in N 58 nuclei are nearly spherical, while those with N 60 have a rotational character. Nuclear lifetimes as short as a few picoseconds can be measured using fast-timing techniques with LaBr3(Ce) scintillators, yielding a key ingredient in the systematic study of the shape evolution in this region.We used neutron-induced fission of 241Pu and 235U to study lifetimes of excited states in fission fragments in the A ∼ 100 region with the EXILL-FATIMA array located at the PF1B cold neutron beam line at the Institut Laue-Langevin. In particular, we applied the generalized centroid difference method to deduce lifetimes of low-lying states for the nuclei 98Zr (N = 58), 100Zr,and 102Zr (N 60). The results are discussed in the context of the presumed phase transition in the Zr chain by comparing the experimental transition strengths with the theoretical calculations using the interacting boson model and the Monte Carlo shell model
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