62 research outputs found
Beta Spectrum Generator: High precision allowed spectrum shapes
Several searches for Beyond Standard Model physics rely on an accurate and
highly precise theoretical description of the allowed spectrum.
Following recent theoretical advances, a C++ implementation of an analytical
description of the allowed beta spectrum shape was constructed. It implements
all known corrections required to give a theoretical description accurate to a
few parts in . The remaining nuclear structure-sensitive input can
optionally be calculated in an extreme single-particle approximation with a
variety of nuclear potentials, or obtained through an interface with more
state-of-the-art computations. Due to its relevance in modern neutrino physics,
the corresponding (anti)neutrino spectra are readily available with appropriate
radiative corrections. In the interest of user-friendliness, a graphical
interface was developed in Python with a coupling to a variety of nuclear
databases. We present several test cases and illustrate potential usage of the
code. Our work can be used as the foundation for current and future
high-precision experiments related to the beta decay process.
Source code: https://github.com/leenderthayen/BSG
Documentation: http://bsg.readthedocs.i
Study of weak magnetism by precision spectrum shape measurements in nuclear beta decay
Nuclear beta decays play an important role in uncovering the nature of the weak interaction. The weak magnetism (WM) form factor, bWM, is generally a small correction to the beta decay rate that arises at first order as an interference term between the dominant Gamow-Teller and the magnetic dipole contributions to the weak current. This form factor is still poorly known for nuclei with higher atomic number. We performed a careful analysis of the measured beta spectrum shape for Gamow-Teller transitions in In and P nuclei. The precision spectrum shape measurements were carried out using the miniBETA spectrometer consisting of a low-mass, low-Z multi-wire gas tracker and a plastic scintillator energy detector. The preliminary results for the weak magnetism extraction for In and P nuclei are presented
Characterization of a continuous muon source for the Muon-Induced X-ray Emission (MIXE) Technique
The toolbox for material characterization has never been richer than today.
Great progress with all kinds of particles and interaction methods provide
access to nearly all properties of an object under study. However, a
tomographic analysis of the subsurface region remains still a challenge today.
In this regard, the Muon-Induced X-ray Emission (MIXE) technique has seen
rebirth fueled by the availability of high intensity muon beams. We report here
a study conducted at the Paul Scherrer Institute (PSI). It demonstrates that
the absence of any beam time-structure leads to low pile-up events and a high
signal-to-noise ratio (SNR) with less than one hour acquisition time per sample
or data point. This performance creates the perspective to open this technique
to a wider audience for the routine investigation of non-destructive and
depth-sensitive elemental compositions, for example in rare and precious
samples. Using a hetero-structured sample of known elements and thicknesses, we
successfully detected the characteristic muonic X-rays, emitted during the
capture of a negative muon by an atom, and the gamma-rays resulting from the
nuclear capture of the muon, characterizing the capabilities of MIXE at PSI.
This sample emphasizes the quality of a continuous beam, and the exceptional
SNR at high rates. Such sensitivity will enable totally new statistically
intense aspects in the field of MIXE, e.g. elemental 3D-tomography and chemical
analysis. Therefore, we are currently advancing our proof-of-concept
experiments with the goal of creating a full fledged permanently operated user
station to make MIXE available to the wider scientific community as well as
industry
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
Tests of P-violation in neutron and nuclear beta decay
An overview is given of the present status of parity violation tests in neutron
decay and nuclear beta decay. Prospects for improved and new measurements
are discussed as well.status: publishe
Correlation and spectrum shape measurements in beta-decay probing the standard model
The beta-decay process offers unique possibilities for testing the fundamental symmetries of the standard model and searching for non-standard model components in the weak interaction. Here a non-exhaustive review of this field is given highlighting a number of key experiments or recently performed experiments. Also included are new and ongoing developments providing new opportunities for further significant progress in this research field in the era of
the large hadron collider.status: publishe
- …