Overview of the Cosmic Axion Spin Precession Experiment (CASPEr)

Towards an electrostatic storage ring for fundamental physics measurements

We describe a new table-top electrostatic storage ring concept for 30 keV polarized ions with fixed spin orientation. The device will ultimately be capable of measuring magnetic fields with a resolution of 10−20 T with sub-mHz bandwidth. With the possibility to store different kinds of ions or ionic molecules and access to prepare and probe states of the systems using lasers and SQUIDs, it can be used to search for electric dipole moments (EDMs) of electrons and nucleons, as well as axion-like particle dark matter and dark photon dark matter. Its sensitivity potential stems from several hours of storage time, comparably long spin coherence times, and the possibility to trap up to 109 particles in bunches with possibly different state preparations for differential measurements. As a dark matter experiment, it is most sensitive in the mass range of 10−10 to 10−19 eV, where it can potentially probe couplings orders of magnitude below current and proposed laboratory experiments.

Cryogenic probe for low-noise, high-frequency electronic measurements

The design and performance of a low-noise, modular cryogenic probe, which is applicable to a wide range of measurements over a broad range of working frequencies, temperatures, and magnetic fields, is presented. The design of the probe facilitates the exchange of sample holders and sample-stage amplifiers, which, combined with its characteristic low transmission and reflection loss, make this design suitable for high precision or low sensitivity measurements. The specific example of measuring the shot noise of magnetic tunnel junctions is discussed. We highlight various design characteristics chosen specifically to expand the applicability of the probe to measurement techniques such as nuclear magnetic resonance.

Direct detection of dark matter-APPEC committee report

This report provides an extensive review of the experimental programme of direct detection searches of particle dark matter. It focuses mostly on European efforts, both current and planned, but does it within a broader context of a worldwide activity in the field. It aims at identifying the virtues, opportunities and challenges associated with the different experimental approaches and search techniques. It presents scientific and technological synergies, both existing and emerging, with some other areas of particle physics, notably collider and neutrino programmes, and beyond. It addresses the issue of infrastructure in light of the growing needs and challenges of the different experimental searches. Finally, the report makes a number of recommendations from the perspective of a long-term future of the field. They are introduced, along with some justification, in the opening overview and recommendations section and are next summarised at the end of the report. Overall, we recommend that the direct search for dark matter particle interactions with a detector target should be given top priority in astroparticle physics, and in all particle physics, and beyond, as a positive measurement will provide the most unambiguous confirmation of the particle nature of dark matter in the Universe.

Towards large-scale steady-state enhanced nuclear magnetization with in situ detection

Signal amplification by reversible exchange (SABRE) boosts NMR signals of various nuclei enabling new applications spanning from magnetic resonance imaging to analytical chemistry and fundamental physics. SABRE is especially well positioned for continuous generation of enhanced magnetization on a large scale; however, several challenges need to be addressed for accomplishing this goal. Specifically, SABRE requires (i) a specialized catalyst capable of reversible H₂ activation and (ii) physical transfer of the sample from the point of magnetization generation to the point of detection (e.g., a high-field or a benchtop nuclear magnetic resonance [NMR] spectrometer). Moreover, (iii) continuous parahydrogen bubbling accelerates solvent (e.g., methanol) evaporation, thereby limiting the experimental window to tens of minutes per sample. In this work, we demonstrate a strategy to rapidly generate the best-to-date precatalyst (a compound that is chemically modified in the course of the reaction to yield the catalyst) for SABRE, [Ir(IMes)(COD)Cl] (IMes = 1,3-bis-[2,4,6-trimethylphenyl]-imidazol-2-ylidene; COD = cyclooctadiene) via a highly accessible synthesis. Second, we measure hyperpolarized samples using a home-built zero-field NMR spectrometer and study the field dependence of hyperpolarization directly in the detection apparatus, eliminating the need to physically move the sample during the experiment. Finally, we prolong the measurement time and reduce evaporation by presaturating parahydrogen with the solvent vapor before bubbling into the sample. These advancements extend opportunities for exploring SABRE hyperpolarization by researchers from various fields and pave the way to producing large quantities of hyperpolarized material for long-lasting detection of SABRE-derived nuclear magnetization.