113 research outputs found
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
A pulsed, mono-energetic and angular-selective UV photo-electron source for the commissioning of the KATRIN experiment
The KATRIN experiment aims to determine the neutrino mass scale with a
sensitivity of 200 meV/c^2 (90% C.L.) by a precision measurement of the shape
of the tritium -spectrum in the endpoint region. The energy analysis of
the decay electrons is achieved by a MAC-E filter spectrometer. To determine
the transmission properties of the KATRIN main spectrometer, a mono-energetic
and angular-selective electron source has been developed. In preparation for
the second commissioning phase of the main spectrometer, a measurement phase
was carried out at the KATRIN monitor spectrometer where the device was
operated in a MAC-E filter setup for testing. The results of these measurements
are compared with simulations using the particle-tracking software
"Kassiopeia", which was developed in the KATRIN collaboration over recent
years.Comment: 19 pages, 16 figures, submitted to European Physical Journal
Characterization of low temperature metallic magnetic calorimeters having gold absorbers with implanted Ho ions
For the first time we have investigated the behavior of fully
micro-fabricated low temperature metallic magnetic calorimeters (MMCs) after
undergoing an ion-implantation process. This experiment had the aim to show the
possibility to perform a high precision calorimetric measurement of the energy
spectrum following the electron capture of Ho using MMCs having the
radioactive Ho ions implanted in the absorber. The implantation of
Ho ions was performed at ISOLDE-CERN. The performance of a detector
that underwent an ion-implantation process is compared to the one of a detector
without implanted ions. The results show that the implantation dose of ions
used in this experiment does not compromise the properties of the detector. In
addition an optimized detector design for future Ho experiments is
presented
The Electron Capture Ho Experiment ECHo: an overview
The determination of the absolute scale of the neutrino masses is one of the
most challenging present questions in particle physics. The most stringent
limit, eV, was achieved for the electron
anti-neutrino mass \cite{numass}. Different approaches are followed to achieve
a sensitivity on neutrino masses in the sub-eV range. Among them, experiments
exploring the beta decay or electron capture of suitable nuclides can provide
information on the electron neutrino mass value. We present the Electron
Capture Ho experiment ECHo, which aims to investigate the electron
neutrino mass in the sub-eV range by means of the analysis of the
calorimetrically measured energy spectrum following electron capture of
Ho. A high precision and high statistics spectrum will be measured with
arrays of metallic magnetic calorimeters. We discuss some of the essential
aspects of ECHo to reach the proposed sensitivity: detector optimization and
performance, multiplexed readout, Ho source production and
purification, as well as a precise theoretical and experimental
parameterization of the calorimetric EC spectrum including in particular the
value of . We present preliminary results obtained with a
first prototype of single channel detectors as well as a first 64-pixel chip
with integrated micro-wave SQUID multiplexer, which will already allow to
investigate in the eV range.Comment: Contribution to the LTD15 Conference Proceeding
KATRIN background due to surface radioimpurities
The goal of the KArlsruhe TRItrium Neutrino (KATRIN) experiment is the determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c at 90 % C.L.. This goal can only be achieved with a very low background level in the order of 10 mcps in the detector region of interest. A possible background source are α-decays on the inner surface of the KATRIN Main Spectrometer. Rydberg atoms, produced in sputtering processes accompanying the α-decays, are not influenced by electric or magnetic fields and freely propagate inside the vacuum of the Main Spectrometer. Here, they can be ionized by thermal radiation and the released electrons directly contribute to the KATRIN background. Two α-sources, Ra and Th, were installed at the Main Spectrometer with the purpose of temporarily increasing the background in order to study α-decay induced background processes. In this paper, we present a possible background generation mechanism and measurements performed with these two radioactive sources. Our results show a clear correlation between α-activity on the inner spectrometer surface and background from the volume of the spectrometer. Two key characteristics of the Main Spectrometer background – the dependency on the inner electrode offset potential, and the radial distribution – could be reproduced with this artificially induced background. These findings indicate a high contribution of α-decay induced events to the residual KATRIN background
The electron capture in Ho experiment – ECHo
Neutrinos, and in particular their tiny but non-vanishing masses, can be considered one of the doors towards physics beyond the Standard Model. Precision measurements of the kinematics of weak interactions, in particular of the H β-decay and the Ho electron capture (EC), represent the only model independent approach to determine the absolute scale of neutrino masses. The electron capture in Ho experiment, ECHo, is designed to reach sub-eV sensitivity on the electron neutrino mass by means of the analysis of the calorimetrically measured electron capture spectrum of the nuclide Ho. The maximum energy available for this decay, about 2.8 keV, constrains the type of detectors that can be used. Arrays of low temperature metallic magnetic calorimeters (MMCs) are being developed to measure the Ho EC spectrum with energy resolution below 3 eV FWHM and with a time resolution below 1 μs. To achieve the sub-eV sensitivity on the electron neutrino mass, together with the detector optimization, the availability of large ultra-pure Ho samples, the identification and suppression of background sources as well as the precise parametrization of the Ho EC spectrum are of utmost importance. The high-energy resolution Ho spectra measured with the first MMC prototypes with ion-implanted Ho set the basis for the ECHo experiment. We describe the conceptual design of ECHo and motivate the strategies we have adopted to carry on the present medium scale experiment, ECHo-1K. In this experiment, the use of 1 kBq Ho will allow to reach a neutrino mass sensitivity below 10 eV/c. We then discuss how the results being achieved in ECHo-1k will guide the design of the next stage of the ECHo experiment, ECHo-1M, where a source of the order of 1 MBq Ho embedded in large MMCs arrays will allow to reach sub-eV sensitivity on the electron neutrino mass
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