406 research outputs found
Light sterile neutrino sensitivity of 163Ho experiments
We explore the sensitivity of Ho electron capture experiments to
neutrino masses in the standard framework of three-neutrino mixing and in the
framework of 3+1 neutrino mixing with a sterile neutrino which mixes with the
three standard active neutrinos, as indicated by the anomalies found in
short-baseline neutrino oscillations experiments. We calculate the sensitivity
to neutrino masses and mixing for different values of the energy resolution of
the detectors, of the unresolved pileup fraction and of the total statistics of
events, considering the expected values of these parameters in the two planned
stages of the ECHo project (ECHo-1k and ECHo-1M). We show that an extension of
the ECHo-1M experiment with the possibility to collect events will be
competitive with the KATRIN experiment. This statistics will allow to explore
part of the 3+1 mixing parameter space indicated by the global analysis of
short-baseline neutrino oscillation experiments. In order to cover all the
allowed region, a statistics of about events will be needed.Comment: 11 page
MRI/TRUS data fusion for brachytherapy
BACKGROUND: Prostate brachytherapy consists in placing radioactive seeds for
tumour destruction under transrectal ultrasound imaging (TRUS) control. It
requires prostate delineation from the images for dose planning. Because
ultrasound imaging is patient- and operator-dependent, we have proposed to fuse
MRI data to TRUS data to make image processing more reliable. The technical
accuracy of this approach has already been evaluated. METHODS: We present work
in progress concerning the evaluation of the approach from the dosimetry
viewpoint. The objective is to determine what impact this system may have on
the treatment of the patient. Dose planning is performed from initial TRUS
prostate contours and evaluated on contours modified by data fusion. RESULTS:
For the eight patients included, we demonstrate that TRUS prostate volume is
most often underestimated and that dose is overestimated in a correlated way.
However, dose constraints are still verified for those eight patients.
CONCLUSIONS: This confirms our initial hypothesis
First Calorimetric Measurement of OI-line in the Electron Capture Spectrum of Ho
The isotope Ho undergoes an electron capture process with a
recommended value for the energy available to the decay, , of about
2.5 keV. According to the present knowledge, this is the lowest
value for electron capture processes. Because of that, Ho is the best
candidate to perform experiments to investigate the value of the electron
neutrino mass based on the analysis of the calorimetrically measured spectrum.
We present for the first time the calorimetric measurement of the atomic
de-excitation of the Dy daughter atom upon the capture of an electron
from the 5s shell in Ho, OI-line. The measured peak energy is 48 eV.
This measurement was performed using low temperature metallic magnetic
calorimeters with the Ho ion implanted in the absorber.
We demonstrate that the calorimetric spectrum of Ho can be measured
with high precision and that the parameters describing the spectrum can be
learned from the analysis of the data. Finally, we discuss the implications of
this result for the Electron Capture Ho experiment, ECHo, aiming to
reach sub-eV sensitivity on the electron neutrino mass by a high precision and
high statistics calorimetric measurement of the Ho spectrum.Comment: 5 pages, 3 figure
On the keV sterile neutrino search in electron capture
A joint effort of cryogenic microcalorimetry (CM) and high-precision
Penning-trap mass spectrometry (PT-MS) in investigating atomic orbital electron
capture (EC) can shed light on the possible existence of heavy sterile
neutrinos with masses from 0.5 to 100 keV. Sterile neutrinos are expected to
perturb the shape of the atomic de-excitation spectrum measured by CM after a
capture of the atomic orbital electrons by a nucleus. This effect should be
observable in the ratios of the capture probabilities from different orbits.
The sensitivity of the ratio values to the contribution of sterile neutrinos
strongly depends on how accurately the mass difference between the parent and
the daughter nuclides of EC-transitions can be measured by, e.g., PT-MS. A
comparison of such probability ratios in different isotopes of a certain
chemical element allows one to exclude many systematic uncertainties and thus
could make feasible a determination of the contribution of sterile neutrinos on
a level below 1%. Several electron capture transitions suitable for such
measurements are discussed.Comment: 16 pages, 9 figures, 2 table
CONTAINER LOCALISATION AND MASS ESTIMATION WITH AN RGB-D CAMERA
In the research area of human-robot interactions, the automatic estimation of the mass of a container manipulated by a person leveraging only visual information is a challenging task. The main challenges consist of occlusions, different filling materials and lighting conditions. The mass of an object constitutes key information for the robot to correctly regulate the force required to grasp the container. We propose a single RGB-D camera-based method to locate a manipulated container and estimate its empty mass i.e., independently of the presence of the content. The method first automatically selects a number of candidate containers based on the distance with the fixed frontal view, then averages the mass predictions of a lightweight model to provide the final estimation. Results on the CORSMAL Containers Manipulation dataset show that the proposed method estimates empty container mass obtaining a score of 71.08% under different lighting or filling conditions
Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter
The Thorium-229 isotope features a nuclear isomer state with an extremely low
energy. The currently most accepted energy value, 7.8 +- 0.5 eV, was obtained
from an indirect measurement using a NASA x-ray microcalorimeter with an
instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic
microcalorimeters with an energy resolution down to a few eV can be used to
measure the isomer energy. In particular, resolving the 29.18 keV doublet in
the \gamma-spectrum following the \alpha-decay of Uranium-233, corresponding to
the decay into the ground and isomer state, allows to measure the isomer
transition energy without additional theoretical input parameters, and increase
the energy accuracy. We study the possibility of resolving the 29.18 keV line
as a doublet and the dependence of the attainable precision of the energy
measurement on the signal and background count rates and the instrumental
resolution.Comment: 32 pages, 8 figures, eq. (3) correcte
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