18 research outputs found
Gas electron tracking detector for beta decay experiments
For identification and 3D-tracking of low-energy electrons a new type of
gas-based detector was designed that minimizes scattering and energy loss. The
current version of the detector is a combination of a plastic scintillator,
serving as a trigger source and energy detector, and a hexagonally structured
multi-wire drift chamber (MWDC), filled with a mixture of helium and isobutane
gas. The drift time information is used to track particles in the plane
perpendicular to the wires, while a charge division technique provides spatial
information along the wires. The gas tracker was successfully used in the
miniBETA project as a beta spectrometer for a measurement of the weak magnetism
form factor in nuclear beta decay. The precision of the three-dimensional
electron tracking, in combination with low-mass, low-Z materials and
identification of backscattering from scintillator, facilitated a reduction of
the main systematics effects. At certain conditions, a spatial resolution
better than 0.5 mm was obtained in the plane perpendicular to the wires, while
resolutions of about 6 mm were achieved along wires. Thanks to precise tracking
information, it is possible to eliminate electrons and other particles not
originating from the desired decay with high efficiency. Additionally, using
the coincidence between MWDC and scintillator, background from gamma emission
typically accompanying radioactive decays, was highly suppressed. An overview
of different event topologies is presented together with the tracker's ability
to correctly recognize them. The analysis is supported by Monte Carlo
simulations using Geant4 and Garfield++ packages. Finally, the preliminary
results from the 114In spectrum study are presented.Comment: 5 pages, 3 figures, accepted for publication in JINST - PSD12(2021
BRAND – search for BSM physics at TeV scale by exploring transverse polarization of electrons emitted in neutron decay
Neutron and nuclear beta decay correlation coefficients are linearly sensitive to the exotic scalar and tensor interactions that are not included in the Standard Model (SM). The proposed experiment will measure simultaneously 11 neutron correlation coefficients (a, a, B, D, H, L, N, R, S, U, V) where 7 of them (H, L, N, R, S, U, V) depend on the transverse electron polarization – a quantity that vanishes for the SM weak interaction. The neutron decay correlation coefficients H, L, S, U, V were never attempted experimentally before. The expected ultimate sensitivity of the proposed experiment that currently takes off on the cold neutron beamline PF1B at the Institut Laue-Langevin, Grenoble, France, is comparable to that of the planned electron spectrum shape measurements in neutron and nuclear β decays but offers completely different systematics and additional sensitivity to imaginary parts of the scalar and tensor couplings
INITIAL TESTS OF MiniBETA SPECTROMETER PERFORMANCE
© 2018 Jagellonian University. All rights reserved. MiniBETA is a new spectrometer incorporating a low-pressure multiwire drift chamber (MWDC). It is designed for beta spectrum shape measurements and to improve knowledge on electron backscattering in the about 100 keV to a few MeV region. After the commissioning phase, which we report on here, the spectrometer will first be used for the latter purpose. This will help reducing the systematic uncertainty in beta spectrum shape measurements. The performance of the trajectory recognition algorithm was investigated using cosmic muons as the source of the primary ionization. For the initial test, the chamber was filled with a mixture of helium-isobutane (50/50) at 600 mbar. A single cell efficiency η higher than 0.98 within almost the entire cell was achieved and the single cell spatial resolution in the drift plane reached σ = 0:4 mm for most of the cells in the chamber.status: publishe
A first extraction of the weak magnetism form factor and Fierz interference term from the In Sn Gamow-Teller transition
International audienceSpectrum shape measurements in nuclear decay can be used to test physics beyond the Standard Model with results being complementary to high-energy collider experiments. In particular, Beyond Standard Model sensitivity of the weak interaction is expressed through the so-called Fierz interference term. Additionally, the spectrum shape is a useful tool to probe Standard Model effects, among which the most prominent is \textit{weak magnetism}, a higher-order recoil correction induced by nuclear pion exchange. To study effects in the spectrum shape at a precision level competitive with the LHC, a new spectrometer was designed and built. It consists of a 3D low-pressure gas electron tracker and a plastic scintillator used for triggering the data acquisition and recording the particle energy. In this Letter, the results from spectrum shape measurements on the allowed Gamow-Teller transition are presented, including a first extraction of the weak magnetism form factor in the high nuclear mass range and a new estimate of the confidence interval for the Fierz interference term
A first extraction of the weak magnetism form factor and Fierz interference term from the In Sn Gamow-Teller transition
International audienceSpectrum shape measurements in nuclear decay can be used to test physics beyond the Standard Model with results being complementary to high-energy collider experiments. In particular, Beyond Standard Model sensitivity of the weak interaction is expressed through the so-called Fierz interference term. Additionally, the spectrum shape is a useful tool to probe Standard Model effects, among which the most prominent is \textit{weak magnetism}, a higher-order recoil correction induced by nuclear pion exchange. To study effects in the spectrum shape at a precision level competitive with the LHC, a new spectrometer was designed and built. It consists of a 3D low-pressure gas electron tracker and a plastic scintillator used for triggering the data acquisition and recording the particle energy. In this Letter, the results from spectrum shape measurements on the allowed Gamow-Teller transition are presented, including a first extraction of the weak magnetism form factor in the high nuclear mass range and a new estimate of the confidence interval for the Fierz interference term
BRAND – Search for BSM physics at TeV scale by exploring transverse polarization of electrons emitted in neutron decay
Neutron and nuclear beta decay correlation coefficients are linearly sensitive to the exotic scalar
and tensor interactions that are not included in the Standard Model (SM). The proposed experiment will
measure simultaneously 11 neutron correlation coefficients (a, A, B, D, H, L, N, R, S, U, V) where 7 of
them (H, L, N, R, S, U, V) depend on the transverse electron polarization – a quantity that vanishes for
the SM weak interaction. The neutron decay correlation coefficients H, L, S, U, V were never attempted
experimentally before. The expected ultimate sensitivity of the proposed experiment that currently takes off
on the cold neutron beamline PF1B at the Institut Laue-Langevin, Grenoble, France, is comparable to that
of the planned electron spectrum shape measurements in neutron and nuclear β decays but offers completely
different systematics and additional sensitivity to imaginary parts of the scalar and tensor couplings.status: publishe