arXiv subjects

A. Phipps

Publications and source records attributed to A. Phipps.

At least 19 recordsLinked to original sources

arXiv2026

The Eos detector: a demonstrator of hybrid optical detection technology

Eos is an R&D testbed for hybrid detector technologies, featuring state-of-the-art sub-ns photosensors, the first implementation of dichroicons in a large-scale demonstrator, and the deployment of novel detection media such as water-based liquid scintillator (WbLS). By separating Cherenkov and scintillation light, Eos leverages the benefits of both to explore the potential of next-generation neutrino technologies. An extensive radioactive source calibration program enables the characterization of position, direction, and energy reconstruction performance of a variety of target materials. Furthermore, Eos will provide data to refine optical models and inform the development and simulation of future neutrino experiments. This paper describes the as-built design and data-taking plan of Eos, outlining its scientific motivations and role in the development of future detector technologies.

physics.ins-det↗

arXiv2026

Performance of the Eos detector with water

In this manuscript we present the first results from Eos, a four tonne optical detector located at the University of California, Berkeley. The primary goal of Eos is to demonstrate the performance capabilities of scintillation-based, 'hybrid' detector technology for future neutrino detectors. The data presented were collected while both the inner target vessel and the outer buffer vessel were filled with water. The water target acts as a well-understood medium that produces only Cherenkov light, which can be used to calibrate and develop the detector model and reconstruction algorithms prior to the deployment of scintillating material. Using deployed optical and radioactive calibration sources, a series of detailed detector calibrations are performed. These enable a suite of tests for various reconstruction algorithms. Simulations that use calibrated models are compared with the data across a variety of different types of calibration sources, source positions, and rotations.

hep-ex↗

arXiv2025

SPLENDOR: a novel detector platform to search for light dark matter with narrow-gap semiconductors

We present the design and current status of SPLENDOR, a novel detector platform that combines narrow-gap semiconductor targets with low-noise charge readout to achieve sensitivity to dark matter energy deposits well below the eV scale. SPLENDOR is designed to be a modular and scalable system able to accommodate different target materials and signal readout technologies. SPLENDOR's present strategy entails: (i) the use of strongly correlated f-electron semiconductors with anisotropic electronic structures to enable not only sub-eV energy thresholds, but also directional sensitivity to the incoming dark matter flux, allowing for signal-background discrimination via daily modulation, and (ii) custom charge readout based on cryogenic high-electron-mobility transistor (cryoHEMT) amplifiers approaching single-electron resolution. We report on the selection and characterization of Eu$_5$In$_2$Sb$_6$ as the target material for SPLENDOR's first prototype detector, as well as the development and calibration of the prototype amplifier chain, achieving a measured charge resolution of 20$\pm$7 electrons in silicon test samples, consistent with predicted performance. This provides a demonstration of the detector architecture, which is now ready for deployment in a dark matter search campaign to deliver SPLENDOR's first science results. Finally, we present estimates of sensitivity reach in the parameter space of athermally produced relic dark matter under high- and low-background environments, and for various amplifier technology upgrades with increasing performance, including planned quantum sensing upgrades in order to achieve our ultimate goal of sub-electron resolution in optimized systems. SPLENDOR provides a novel approach to dark matter direct detection, combining quantum sensing with material's design to open new avenues of exploration in the sub-MeV mass range of dark matter parameter space.

physics.ins-det↗

arXiv2023

Two-Stage Cryogenic HEMT Based Amplifier For Low Temperature Detectors

To search for dark matter candidates with masses below $\mathcal{O}$(MeV), the SPLENDOR (Search for Particles of Light dark mattEr with Narrow-gap semiconDuctORs) experiment is developing novel narrow-bandgap semiconductors with electronic bandgaps on the order of 1-100 meV. In order to detect the charge signal produced by scattering or absorption events, SPLENDOR has designed a two-stage cryogenic HEMT-based amplifier with an estimated charge resolution approaching the single-electron level. A low-capacitance ($\sim$1.6 pF) HEMT is used as a buffer stage at $T=10\,\mathrm{mK}$ to mitigate effects of stray capacitance at the input. The buffered signal is then amplified by a higher-capacitance ($\sim$200 pF) HEMT amplifier stage at $T=4\,\mathrm{K}$. Importantly, the design of this amplifier makes it usable with any insulating material - allowing for rapid prototyping of a variety of novel detector materials. We present the two-stage cryogenic amplifier design, preliminary voltage noise performance, and estimated charge resolution of 7.2 electrons.

physics.ins-det↗

arXiv2023

Electromagnetic modeling and science reach of DMRadio-m$^3$

DMRadio-m$^3$ is an experiment that is designed to be sensitive to KSVZ and DFSZ QCD axion models in the 10--200\,MHz (41 neV$/c^2$ -- 0.83 $\mu$eV/$c^2$) range. The experiment uses a solenoidal dc magnetic field to convert an axion dark-matter signal to an ac electromagnetic response in a coaxial copper pickup. The current induced by this axion signal is measured by dc SQUIDs. In this work, we present the electromagnetic modeling of the response of the experiment to an axion signal over the full frequency range of DMRadio-m$^3$, which extends from the low-frequency, lumped-element limit to a regime where the axion Compton wavelength is only a factor of two larger than the detector size. With these results, we determine the live time and sensitivity of the experiment. The primary science goal of sensitivity to DFSZ axions across 30--200 MHz can be achieved with a $3\sigma$ live scan time of 2.9 years.

hep-ex↗

arXiv2022

Projected Sensitivity of DMRadio-m$^3$: A Search for the QCD Axion Below $1\,μ$eV

The QCD axion is one of the most compelling candidates to explain the dark matter abundance of the universe. With its extremely small mass ($\ll 1\,\mathrm{eV}/c^2$), axion dark matter interacts as a classical field rather than a particle. Its coupling to photons leads to a modification of Maxwell's equations that can be measured with extremely sensitive readout circuits. DMRadio-m$^3$ is a next-generation search for axion dark matter below $1\,μ$eV using a $>4$ T static magnetic field, a coaxial inductive pickup, a tunable LC resonator, and a DC-SQUID readout. It is designed to search for QCD axion dark matter over the range $20\,\mathrm{neV}\lesssim m_ac^2\lesssim 800\,\mathrm{neV}$ ($5\,\mathrm{MHz}<ν<200\,\mathrm{MHz}$). The primary science goal aims to achieve DFSZ sensitivity above $m_ac^2\approx 120$ neV (30 MHz), with a secondary science goal of probing KSVZ axions down to $m_ac^2\approx40\,\mathrm{neV}$ (10 MHz).

hep-ex↗

arXiv2022

New Horizons: Scalar and Vector Ultralight Dark Matter

The last decade has seen unprecedented effort in dark matter model building at all mass scales coupled with the design of numerous new detection strategies. Transformative advances in quantum technologies have led to a plethora of new high-precision quantum sensors and dark matter detection strategies for ultralight ($<10\,$eV) bosonic dark matter that can be described by an oscillating classical, largely coherent field. This white paper focuses on searches for wavelike scalar and vector dark matter candidates.

hep-ex↗

arXiv2022

Introducing DMRadio-GUT, a search for GUT-scale QCD axions

The QCD axion is a leading dark matter candidate that emerges as part of the solution to the strong CP problem in the Standard Model. The coupling of the axion to photons is the most common experimental probe, but much parameter space remains unexplored. The coupling of the QCD axion to the Standard Model scales linearly with the axion mass; therefore, the highly-motivated region 0.4-120 neV, corresponding to a GUT-scale axion, is particularly difficult to reach. This paper presents the design requirements for a definitive search for GUT-scale axions and reviews the technological advances needed to enable this program.

hep-ex↗

arXiv2022

Snowmass2021 Cosmic Frontier: The landscape of low-threshold dark matter direct detection in the next decade

The search for particle-like dark matter with meV-to-GeV masses has developed rapidly in the past few years. We summarize the science case for these searches, the recent progress, and the exciting upcoming opportunities. Funding for Research and Development and a portfolio of small dark matter projects will allow the community to capitalize on the substantial recent advances in theory and experiment and probe vast regions of unexplored dark-matter parameter space in the coming decade.

hep-ph↗

arXiv2020

First Dark Matter Constraints from a SuperCDMS Single-Charge Sensitive Detector

We present the first limits on inelastic electron-scattering dark matter and dark photon absorption using a prototype SuperCDMS detector having a charge resolution of 0.1 electron-hole pairs (CDMS HVeV, a 0.93 gram CDMS HV device). These electron-recoil limits significantly improve experimental constraints on dark matter particles with masses as low as 1 MeV/$\mathrm{c^2}$. We demonstrate a sensitivity to dark photons competitive with other leading approaches but using substantially less exposure (0.49 gram days). These results demonstrate the scientific potential of phonon-mediated semiconductor detectors that are sensitive to single electronic excitations.

hep-ex↗

arXiv2019

Low-noise HEMTs for Coherent Elastic Neutrino Scattering and Low-Mass Dark Matter Cryogenic Semiconductor Detectors

We present the noise performance of High Electron Mobility Transistors (HEMT) developed by CNRS-C2N laboratory. Various HEMT's gate geometries with 2 pF to 230 pF input capacitance have been studied at 4 K. A model for both voltage and current noises has been developed with frequency dependence up to 1 MHz. These HEMTs exhibit low dissipation, excellent noise performance and can advantageously replace traditional Si-JFETs for the readout of high impedance thermal sensor and semiconductor ionization cryogenic detectors. Our model predicts that cryogenic germanium detectors of 30 g with 10 eV heat and 20 eVee baseline resolution are feasible if read out by HEMT based amplifiers. Such resolution allows for high discrimination between nuclear and electron recoils at low threshold. This capability is of major interest for Coherent Elastic Neutrino Scattering and low-mass dark matter experiments such as Ricochet and EDELWEISS.

physics.ins-det↗

arXiv2019

Exclusion Limits on Hidden-Photon Dark Matter near 2 neV from a Fixed-Frequency Superconducting Lumped-Element Resonator

We present the design and performance of a simple fixed-frequency superconducting lumped-element resonator developed for axion and hidden photon dark matter detection. A rectangular NbTi inductor was coupled to a Nb-coated sapphire capacitor and immersed in liquid helium within a superconducting shield. The resonator was transformer-coupled to a DC SQUID for readout. We measured a quality factor of $\sim$40,000 at the resonant frequency of 492.027 kHz and set a simple exclusion limit on $\sim$2 neV hidden photons with kinetic mixing angle $\varepsilon\gtrsim1.5\times10^{-9}$ based on 5.14 hours of integrated noise. This test device informs the development of the Dark Matter Radio, a tunable superconducting lumped-element resonator which will search for axions and hidden photons over the 100 Hz to 300 MHz frequency range.

astro-ph.CO↗

arXiv2019

A HEMT-Based Cryogenic Charge Amplifier with sub-100 eVee Ionization Resolution for Massive Semiconductor Dark Matter Detectors

We present the measured baseline ionization resolution of a HEMT-based cryogenic charge amplifier coupled to a CDMS-II detector. The amplifier has been developed to allow massive semiconductor dark matter detectors to retain background discrimination at the low recoil energies produced by low-mass WIMPs. We find a calibrated baseline ionization resolution of $σ_E = 91\,\text{eV}_{ee}$. To our knowledge, this is the best direct ionization resolution achieved with such massive ($\approx$150 pF capacitance) radiation detectors.

physics.ins-det↗

arXiv2018

Nuclear-recoil energy scale in CDMS II silicon dark-matter detectors

The Cryogenic Dark Matter Search (CDMS II) experiment aims to detect dark matter particles that elastically scatter from nuclei in semiconductor detectors. The resulting nuclear-recoil energy depositions are detected by ionization and phonon sensors. Neutrons produce a similar spectrum of low-energy nuclear recoils in such detectors, while most other backgrounds produce electron recoils. The absolute energy scale for nuclear recoils is necessary to interpret results correctly. The energy scale can be determined in CDMS II silicon detectors using neutrons incident from a broad-spectrum $^{252}$Cf source, taking advantage of a prominent resonance in the neutron elastic scattering cross section of silicon at a recoil (neutron) energy near 20 (182) keV. Results indicate that the phonon collection efficiency for nuclear recoils is $4.8^{+0.7}_{-0.9}$% lower than for electron recoils of the same energy. Comparisons of the ionization signals for nuclear recoils to those measured previously by other groups at higher electric fields indicate that the ionization collection efficiency for CDMS II silicon detectors operated at $\sim$4 V/cm is consistent with 100% for nuclear recoils below 20 keV and gradually decreases for larger energies to $\sim$75% at 100 keV. The impact of these measurements on previously published CDMS II silicon results is small.

physics.ins-det↗

arXiv2018

Low-Mass Dark Matter Search with CDMSlite

The SuperCDMS experiment is designed to directly detect weakly interacting massive particles (WIMPs) that may constitute the dark matter in our Galaxy. During its operation at the Soudan Underground Laboratory, germanium detectors were run in the CDMSlite mode to gather data sets with sensitivity specifically for WIMPs with masses ${<}$10 GeV/$c^2$. In this mode, a higher detector-bias voltage is applied to amplify the phonon signals produced by drifting charges. This paper presents studies of the experimental noise and its effect on the achievable energy threshold, which is demonstrated to be as low as 56 eV$_{\text{ee}}$ (electron equivalent energy). The detector-biasing configuration is described in detail, with analysis corrections for voltage variations to the level of a few percent. Detailed studies of the electric-field geometry, and the resulting successful development of a fiducial parameter, eliminate poorly measured events, yielding an energy resolution ranging from ${\sim}$9 eV$_{\text{ee}}$ at 0 keV to 101 eV$_{\text{ee}}$ at ${\sim}$10 eV$_{\text{ee}}$. New results are derived for astrophysical uncertainties relevant to the WIMP-search limits, specifically examining how they are affected by variations in the most probable WIMP velocity and the Galactic escape velocity. These variations become more important for WIMP masses below 10 GeV/$c^2$. Finally, new limits on spin-dependent low-mass WIMP-nucleon interactions are derived, with new parameter space excluded for WIMP masses $\lesssim$3 GeV/$c^2$

astro-ph.CO↗

arXiv2017

Results from the Super Cryogenic Dark Matter Search (SuperCDMS) experiment at Soudan

We report the result of a blinded search for Weakly Interacting Massive Particles (WIMPs) using the majority of the SuperCDMS Soudan dataset. With an exposure of 1690 kg days, a single candidate event is observed, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP--nucleon cross section of $1.4 \times 10^{-44}$ ($1.0 \times 10^{-44}$) cm$^2$ at 46 GeV/$c^2$. These results set the strongest limits for WIMP--germanium-nucleus interactions for masses $>$12 GeV/$c^2$.

hep-ex↗

arXiv2016

Projected Sensitivity of the SuperCDMS SNOLAB experiment

SuperCDMS SNOLAB will be a next-generation experiment aimed at directly detecting low-mass (< 10 GeV/c$^2$) particles that may constitute dark matter by using cryogenic detectors of two types (HV and iZIP) and two target materials (germanium and silicon). The experiment is being designed with an initial sensitivity to nuclear recoil cross sections ~ 1 x 10$^{-43}$ cm$^2$ for a dark matter particle mass of 1 GeV/c$^2$, and with capacity to continue exploration to both smaller masses and better sensitivities. The phonon sensitivity of the HV detectors will be sufficient to detect nuclear recoils from sub-GeV dark matter. A detailed calibration of the detector response to low energy recoils will be needed to optimize running conditions of the HV detectors and to interpret their data for dark matter searches. Low-activity shielding, and the depth of SNOLAB, will reduce most backgrounds, but cosmogenically produced $^{3}$H and naturally occurring $^{32}$Si will be present in the detectors at some level. Even if these backgrounds are x10 higher than expected, the science reach of the HV detectors would be over three orders of magnitude beyond current results for a dark matter mass of 1 GeV/c$^2$. The iZIP detectors are relatively insensitive to variations in detector response and backgrounds, and will provide better sensitivity for dark matter particle masses (> 5 GeV/c$^2$). The mix of detector types (HV and iZIP), and targets (germanium and silicon), planned for the experiment, as well as flexibility in how the detectors are operated, will allow us to maximize the low-mass reach, and understand the backgrounds that the experiment will encounter. Upgrades to the experiment, perhaps with a variety of ultra-low-background cryogenic detectors, will extend dark matter sensitivity down to the "neutrino floor", where coherent scatters of solar neutrinos become a limiting background.

physics.ins-det↗

arXiv2016

Dark matter effective field theory scattering in direct detection experiments

We examine the consequences of the effective field theory (EFT) of dark matter-nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

astro-ph.CO↗