The hyperfine structure of hydrogen-like ions are a unique probe to access nuclear magnetic

moments and nuclear structure. Thus, while eliminating the ignorance of essential links in

metrology due to insufficiently known magnetic moments, at the same time these ions

provide complementary insight into the inner nucleus. The very recently started 3He-

experiment exploits these characteristics to provide a new standard for absolute precision-

magnetometry and determine the nuclear charge and current distribution of 3He.

To this end, a novel four Penning-trap experiment was designed and built. Using novel

techniques, this system enables non-demolition measurements of the nuclear quantum state

and allows sympathetic laser cooling of single, spatially separated ions to sub-thermal

energies [1].

In the first measurement campaign, 3He was investigated by exciting microwave transitions

between the ground-state hyperfine states. This enabled us to determine the nuclear g-factor,

the electronic g-factor and the zero-field ground-state hyperfine-splitting of 3He+ with a

precision of 5*10-10, 3*10-10 and 2*10-11, respectively [2].

Our measurement constitutes the first direct and most precise determination of the 3He+

nuclear magnetic moment. The result is of utmost relevance for absolute precision

magnetometry, as it allows the use of He NMR probes as an independent new standard with

much higher accuracy. In addition, the comparison to advanced theoretical calculations

enables us to determine the size of the 3He nucleus with a precision of 2,4*10-17m.

In future, we aim at a direct determination of the bare nuclear magnetic moment of 3He to be

compared to the bound-state result. For this measurement, it is essential to implement new

methods and technology such as sympathetic laser cooling and a high-precision voltage

source based on Josephson junctions [3]. The latest results, status and the future prospect of

the experiment will be presented.

References

[1] A Mooser et al., J. Phys.: Conf. Ser. 1138, 012004 (2018)

[2] A. Schneider et al., Nature 606, 878 (2022)

[3] A. Schneider et al., Ann. Phys. 531, 1800485 (2019)

Precision measurements of rare decays of charged pions offer important tests of the standard model. The ratio of pi+ -> e+ nu to mu+ nu decay provides the best test of electron–muon weak universality and is uniquely sensitive to non-V-A exotic currents. The rate of pion beta decay pi+ -> pi0 e nu offers a theoretically pristine sensitivity to the Vud matrix element of the CKM matrix.

The gluon distribution function grows with lower and lower momentum fraction very fast. As the total scattering cross section is bound by quantum mechanics, the raise of the gluon density has to be tamed, which is explained by gluon recombination under the color glass condensate (CGC) framework. A definitive discovery of nonlinear effects in QCD and as such the saturation regime would significantly improve our understanding of the nucleon structure and of nuclear interactions at high energy. Two particle azimuthal correlation is one of the most direct and sensitive channels to access the underlying nonlinear gluon dynamics. In this talk, we will present the recent results of forward di-hadron correlations measured at RHIC, together with the signatures of gluon saturation predicted by CGC. New opportunities for measurements with the STAR forward upgrade and future EIC to study the nonlinear effects in QCD will also be discussed.

Precision nuclear physics experiments have long played an important role in searches for physics Beyond the Standard Model (BSM). The traditional particle detection technologies of many of these experiments, semiconductor and scintillation detectors, face fundamental performance limitations that greatly restrict the sensitivity achievable. A new detector paradigm for charged particle detection has the potential to dramatically improve sensitivity in BSM searches. We are working toward this goal by adapting Thermal Kinetic Inductance Detectors (TKIDs) for external charged particle detection. These cryogenic detectors, used in X-ray and gamma spectroscopy as well as dark matter searches, have shown photon energy resolutions on the order of tens of eV and can be multiplexed to create large area detectors. However, TKIDs have not yet been developed for non-embedded charged particle detection. We have designed a Charged Particle TKID (CP-TKID) prototype to optimized for the  detection of the neutron beta decay electron.  In this seminar, I will discuss the development of our initial prototype design and our efforts to characterize its response.

There exists a class of ultralight Dark Matter (DM) models which could form a Bose-Einstein condensate (BEC) in the early universe and behave as a single coherent wave instead of individual particles in galaxies. We show that a generic BEC DM halo intervening along the line of sight of a gravitational wave (GW) signal could induce an observable change in the speed of GW, with the effective refractive index depending only on the mass and self-interaction of the constituent DM particles and the GW frequency. Hence, we propose to use the deviation in the speed of GW as a new probe of the BEC DM parameter space. With a multi-messenger approach to GW astronomy and/or with extended sensitivity to lower GW frequencies, the entire BEC DM parameter space can be effectively probed by our new method in the near future.

We will discuss a simple model of low-energy baryon number violation in order to simultaneously explain the observed matter-antimatter asymmetry and dark matter relic density in the universe. The stability of dark matter is related to the stability of the proton. The model predicts a sizeable rate for the neutron-antineutron oscillation at low energy and a new type of monojet signal at the LHC. There exists an interesting complementarity between the observed baryon asymmetry, ratio of dark matter and baryon abundances, neutron-antineutron oscillation lifetime and the LHC monojet signal. 

Nab, an experiment that allows studying unpolarized neutron beta decay at the Spallation Neutron Source at Oak Ridge National Lab, aims to determine a, the neutrino-electron correlation coefficient, and b, the Fierz interference term, with high precision. Such measurements provide opportunities to search for evidence of extensions to the Standard Model. Nab is presently being constructed. The spectrometer magnet is supposed to arrive in the week I am giving this seminar. Beam readiness planned for end of summer 2018. I will discuss the experiment’s motivation and design, the planned modes of operation, and the performance of its components.