I will discuss a brief history of the experiment, the progress we have made, and our achievements over the past 2 years.
The BeEST Experiment is an international collaboration between experts in many different fields of science. Few of them are low-temperature solid-state physicists. But we all work on some aspect of nuclear decays in superconducting tunnel junctions at temperatures around ~0.1 K. This talk will give a very basic overview of superconductivity and tunnel junctions that I think every collaborator...
I'll present the experimental concept and status for 7Be and 37Ar beam implantations and prospects at TRIUMF.
Neutrinos masses are clear evidence of physics beyond-the-SM. In this talk, we will review mechanisms of neutrino mass generation, focusing on the seesaw mechanism. This mechanism predicts the existence of heavy neutral leptons (or right-handed neutrinos) with rich phenomenology that can be probed with current and future experiments.
We discuss the analysis procedure of the BeEST Phase III and its current status. The discussion will include the application of likelihood profiling for the multiple spectra and various systematic uncertainties that may affect the final limits for the heavy neutrino search.
We will present our latest results on (i) the calculation of electron capture decay probabilities, focusing on the effect of atomic electronic structure modelling and shaking processes [1] (ii) the influence of the tantalum matrix on the P_L/P_K ratio [2].
[1] A. Andoche, L. Mouawad, P.-A. Hervieux, X. Mougeot, J. Machado, and J. P. Santos, Physical Review A 109, 032826 (2024).
[2] In preparation.
I will summarize various atomistic computational efforts to understand materials science effects on the sensitivity of BeEST experiments. Quantum mechanical simulations based on density functional theory (DFT) were applied to understand possible uncertainties (broadening) of capture peak energies due to defects (impurities, clustering, intersitial vs substitutional doping, crystal damage,...
Recent BeEST experimental results displayed that the breadth of the measured peaks associated with electron capture (EC) decay were wider than the inherent resolution of the superconducting tunnel junction detector (STJ). One possible source of the measured peak resolution being appreciably worse than the resolution inherent in the STJ detector is from local imperfections in the materials...
One puzzling observation in the
G4CMP has been developed as an extension to GEANT4 to excite phonons and charges in cryogenic semiconductor crystals in response to energy deposited by radiation. G4CMP is currently being developed towards superconducting processes in the developer's consortium, allowing for modelling the implanted BeEST signal. This talk will demonstrate the applications and value of G4CMP for simulating the...
Poor knowledge of incomplete energy deposition of Auger electrons are a limiting factor in the BeEST's sensitivity to sterile neutrinos. We will present state of the art low-energy scattering simulations and focus on how current approximations determine systematic uncertainties.
At LLNL, we can currently operate up to 32 STJs in two “wet” adiabatic demagnetization refrigerators (ADRs) with liquid N2 and He pre-cooling and a base temperature of ~0.1 K. One of them holds the STJs at the end of a cold finger so that it can be surrounded by large scintillators for coincidence measurements. We also own a “dry” ADR with pulse-tube pre-cooling and a wet dilution refrigerator...
Phase IV of the BeEST experiment requires continuous stable operation of the STJ sensor arrays for 100+ days. This requires transitioning into a dilution refrigerator which will bring new systematics and additional opportunities to deploy recent capabilities demonstrated at LLNL. In this presentation, we will cover the status of STJ sensor operations at PNNL and outline potential areas of improvement.
This contribution will discuss the operation of the VeriCold Dilution Refrigerator (DR) at TRIUMF, a crucial cryogenic instrument for experiments that need ultra-low temperatures and long-term operational duration. A significant challenge was achieving and maintaining stable millikelvin temperatures, essential for effectively operating our Superconducting Tunnel Junction (STJ) detectors for...
Together with Maybell Quantum, we are designing a low-vibration dilution refrigerator with a large and modular sample area. This fridge will be installed on the Mines campus and is a first step towards the Colorado Underground Research Institute (CURIE). At CURIE, the muon flux is 500x suppressed, and we will have low
Dilution refrigerators, in contrast to the single-shot adiabatic demagnetization refrigerators previously utilized in the BeEST experiment, provide continuous cooling power, resulting in a nearly indefinite experimental runtime and a colder, more thermally stable base temperature—properties beneficial for STJ operation. Here, I discuss a bespoke experimental design for testing STJs in dilution...
A challenge in preparing radioactive samples is the dependence on beam time at radioactive isotope facilities. One can imagine implanting large amounts of long-lived isotopes into a target at an isotope facility. The target is then brought to an offline laboratory where specific quantifies of the isotope are extracted from the target via laser ablation. The ablated ions can then be...
The broadening for nuclear recoils observed in BeEST’s STJ experiments is as-yet unexplained. We are working to investigate the origins of this broadening with two proposed control experiments: 1) repeating the 7Be measurements with a phonon-mediated detector, rather than direct pair-breaking, and 2) measuring nuclear recoils from gamma ray emission rather than electron captures. I will...
Gamma-coincidence tagging has proven to be a valuable tool for performing high-selectivity measurements of specific excited state nuclear recoils for the BeEST experiment. In this talk I present experimental concepts for further utilizing coincidence tagging in the BeEST and SALER experimental programs.
The nuclear broadening of the BeEST spectrum as a result of materials effects is poorly constrained. While a precise model of the recoil of dopant radioisotopes in a superconductor such as tantalum and the resulting quasiparticle dynamics in an STJ are challenging, measuring this effect in analogous aluminum-based STJs provides an experimental comparison of this effect. This talk will discuss...
We will discuss the design of a more adaptable device holder for future implantations in the TRIUMF-ISAC facility. This holder will be able to accommodate much larger devices, such as the SLAC Transition Edge Sensors, as well as more objects at the same time so that fewer vacuum breaks are necessary. We are currently building a swap in replacement of the chamber that should be available by June.
New physics coupled to neutrinos are well-motivated extensions of the SM, and could play a role in neutrino mass generation or mediating interactions between the SM and dark sectors. In this talk, we will explore the phenomenology of light neutrinophilic particles, and their signatures in electron capture experiments like BeEST.
We will provide a status update of three-body decay searches in the BeEST data set, focusing on the anticipated sensitivity in the current data set.
The precision of the BeEST measurement can be used to study wavepacket sizes in 7-Be electron capture decays. Predictions for wavepacket sizes vary widely based on the scale of localizing interactions and are largely unconstrained by data. By using Heisenberg’s uncertainty principle and conservation laws, the BeEST measurement places the first experimental limit on the size of decay products...
I will describe some ideas for analyzing the
The SALER experiment aims to expand the precision nuclear recoil measurements in STJs pioneered by the BeEST to much shorter-lived isotopes on-line at FRIB. In this talk we present on the initial commissioning of SALER with a 262 nm UV laser as well as development towards coupling STJs in an ADR cryostat to the FRIB beamline.
We will introduce the proposed ASGARD experiment, which utilises a combination of novel technological steps to perform high precision spectroscopy on short-lived isotopes. The latter is used for TeV-scale searches for new physics and can open up new directions in nuclear physics studies.
I will describe ideas to use optically trapped nanoparticles to search for sterile neutrinos or other new physics by directly measuring the momentum of nuclear recoils from the decay of radioisotopes within the particles. These techniques can provide complementarity to the energy resolving measurements performed by the BeEST, and can allow a number of isotopes to be studied.
In this talk, we will review why low-mass (KeV-MeV) dark matter is an interesting field of study and how cryogenic superconducting techniques could assist in the search for this elusive component of the universe.