134 research outputs found
A mobile Magnetic Sensor Unit for the KATRIN Main Spectrometer
The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the
electron neutrino mass with an unprecedented sensitivity of 0.2 eV/c2, using b
decay electrons from tritium decay. For the control of magnetic field in the
main spectrometer area of the KATRIN experiment a mobile magnetic sensor unit
is constructed and tested at the KATRIN main spectrometer site. The unit moves
on inner rails of the support structures of the low field shaping coils which
are arranged along the the main spectrometer. The unit propagates on a
caterpillar drive and contains an electro motor, battery pack, board
electronics, 2 triaxial flux gate sensors and 2 inclination senors. During
operation all relevant data are stored on board and transmitted to the master
station after the docking station is reached.Comment: 11 pages, 14 figure
Precision high voltage divider for the KATRIN experiment
The Karlsruhe Tritium Neutrino Experiment (KATRIN) aims to determine the
absolute mass of the electron antineutrino from a precise measurement of the
tritium beta-spectrum near its endpoint at 18.6 keV with a sensitivity of 0.2
eV. KATRIN uses an electrostatic retardation spectrometer of MAC-E filter type
for which it is crucial to monitor high voltages of up to 35 kV with a
precision and long-term stability at the ppm level. Since devices capable of
this precision are not commercially available, a new high voltage divider for
direct voltages of up to 35 kV has been designed, following the new concept of
the standard divider for direct voltages of up to 100 kV developed at the
Physikalisch-Technische Bundesanstalt (PTB). The electrical and mechanical
design of the divider, the screening procedure for the selection of the
precision resistors, and the results of the investigation and calibration at
PTB are reported here. During the latter, uncertainties at the low ppm level
have been deduced for the new divider, thus qualifying it for the precision
measurements of the KATRIN experiment.Comment: 22 pages, 12 figure
Technical design and commissioning of the KATRIN large-volume air coil system
The KATRIN experiment is a next-generation direct neutrino mass experiment
with a sensitivity of 0.2 eV (90% C.L.) to the effective mass of the electron
neutrino. It measures the tritium -decay spectrum close to its endpoint
with a spectrometer based on the MAC-E filter technique. The -decay
electrons are guided by a magnetic field that operates in the mT range in the
central spectrometer volume; it is fine-tuned by a large-volume air coil system
surrounding the spectrometer vessel. The purpose of the system is to provide
optimal transmission properties for signal electrons and to achieve efficient
magnetic shielding against background. In this paper we describe the technical
design of the air coil system, including its mechanical and electrical
properties. We outline the importance of its versatile operation modes in
background investigation and suppression techniques. We compare magnetic field
measurements in the inner spectrometer volume during system commissioning with
corresponding simulations, which allows to verify the system's functionality in
fine-tuning the magnetic field configuration. This is of major importance for a
successful neutrino mass measurement at KATRIN.Comment: 32 pages, 16 figure
Using Cold Atoms to Measure Neutrino Mass
We propose a beta decay experiment based on a sample of ultracold atomic
tritium. These initial conditions enable detection of the helium ion in
coincidence with the beta. We construct a two-dimensional fit incorporating
both the shape of the beta-spectrum and the direct reconstruction of the
neutrino mass peak. We present simulation results of the feasible limits on the
neutrino mass achievable in this new type of tritium beta-decay experiment.Comment: 10 pages, 5 figure
Statistical Analysis of future Neutrino Mass Experiments including Neutrino-less Double Beta Decay
We perform a statistical analysis with the prospective results of future
experiments on neutrino-less double beta decay, direct searches for neutrino
mass (KATRIN) and cosmological observations. Realistic errors are used and the
nuclear matrix element uncertainty for neutrino-less double beta decay is also
taken into account. Three benchmark scenarios are introduced, corresponding to
quasi-degenerate, inverse hierarchical neutrinos, and an intermediate case. We
investigate to what extend these scenarios can be reconstructed. Furthermore,
we check the compatibility of the scenarios with the claimed evidence of
neutrino-less double beta decay.Comment: Matches published version: Europhys.Lett.85:51002 (2009). Format
changed suitably for ArXi
On a model with two zeros in the neutrino mass matrix
We consider a Majorana neutrino mass matrix with
, in the basis
where the charged-lepton mass matrix is diagonal. We show that this pattern for
the lepton mass matrices can be enforced by extending the Standard Model with
three scalar SU(2) triplets and by using a horizontal symmetry group
\mathbbm{Z}_4. The Ma--Sarkar (type-II seesaw) mechanism leads to very small
vacuum expectation values for the triplets, thus explaining the smallness of
the neutrino masses; at the same time, that mechanism renders the physical
scalars originating in the triplets very heavy. We show that the conditions
allow both for
a normal neutrino mass spectrum and for an inverted one. In the first case, the
neutrino masses must be larger than and the atmospheric mixing angle
must be practically equal to . In the second case, the
product must be of order one or
larger, thus correlating the large or maximal atmospheric neutrino mixing with
the smallness of the mixing angle .Comment: 13 pages, no figures, plain LaTeX; one equation added, published
references updated, final version for J. Phys.
Neutrino-less Double Beta Decay and Particle Physics
We review the particle physics aspects of neutrino-less double beta decay.
This process can be mediated by light massive Majorana neutrinos (standard
interpretation) or by something else (non-standard interpretations). The
physics potential of both interpretations is summarized and the consequences of
future measurements or improved limits on the half-life of neutrino-less double
beta decay are discussed. We try to cover all proposed alternative realizations
of the decay, including light sterile neutrinos, supersymmetric or left-right
symmetric theories, Majorons, and other exotic possibilities. Ways to
distinguish the mechanisms from one another are discussed. Experimental and
nuclear physics aspects are also briefly touched, alternative processes to
double beta decay are discussed, and an extensive list of references is
provided.Comment: 96 pages, 38 figures. Published versio
Micromachining using focused high energy ion beams
Abstract The combination of deep X-ray lithography with electroforming and micromoulding (i.e., LIGA) has been shown to oer high potential for the production of high aspect-ratio microstructures. The LIGA technique, employing synchrotron light and a suitable X-ray mask, allows production of 3D microstructures in PMMA with aspect ratios around 100. Here we demonstrate that the novel technique of Deep Ion Beam Lithography (DIBL), a direct process utilizing a focused beam of MeV ions scanned in a predetermined pattern over a suitable resist material, can produce three dimensional microstructures with sub-micrometer feature sizes. Microstructures extending up to 100 lm from the substrate with aspect ratios approaching 100 can be produced. Multiple exposures at dierent ion energies allow production of multilayer structures in single resist layers of SU-8, a newly developed, chemically accelerated, negative tone, near UV, photoresist.
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