Detection Of Dark Matter Particles Research Articles

Backaction-evading receivers with magnetomechanical and electromechanical sensors

Today's mechanical sensors are capable of detecting extremely weak perturbations while operating near the standard quantum limit. However, further improvements can be made in both sensitivity and bandwidth when we reduce the noise originating from the process of measurement itself—the quantum-mechanical backaction of measurement—and go below this ‘standard’ limit, possibly approaching the Heisenberg limit. One of the ways to eliminate this noise is by measuring a quantum nondemolition variable such as the momentum in a free-particle system. Here, we propose and characterize theoretical models for direct velocity measurement that utilize traditional electric and magnetic transducer designs to generate a signal while enabling this backaction evasion. We consider the general readout of this signal via electric or magnetic field sensing by creating toy models analogous to the standard optomechanical position-sensing problem, thereby facilitating the assessment of measurement-added noise. Using simple models that characterize a wide range of transducers, we find that the choice of readout scheme—voltage or current—for each mechanical detector configuration implies access to either the position or velocity of the mechanical subsystem. This in turn suggests a path forward for key fundamental physics experiments such as the direct detection of dark matter particles. Published by the American Physical Society 2024

Particle dark matter versus modified gravity

There are at least two possible solutions to the so-called Dark Matter problem. One is to introduce new particles and another one is to modify gravity. In these proceedings of the 182nd Nobel Symposium on dark matter, I question the particle dark matter hypothesis in light of new developments in the gravity sector. To this effect, I review how the CMB anisotropies and the details of structure formation have been used to test the dark matter microscopic properties. I explain how this has led to challenge the Hut-Lee & Weinberg argument and the introduction of light (thermal) dark matter scenarios and dark photon/light Z′. These developments have ultimately paved the way for a comprehensive exploration of the entire dark matter mass spectrum. I then discuss a new theory of modified gravity that appears to be a novel alternative to particle dark matter and ask the question: how to distinguish the two? I expect this question to become extremely relevant in absence of dark matter particle detection in Earth based experiments and in presence of ambiguous astrophysical and cosmological signals.

Dual-phase xenon time projection chambers forrare-event searches.

In the past decade, dual-phase xenon time projection chambers (Xe-TPCs) have emerged as some of the most powerful detectors in the fields of astroparticle physics and rare-event searches. Developed primarily towards the direct detection of dark matter particles, experiments presently operating deep underground have reached target masses at the multi-tonne scale, energy thresholds of approximately 1 keV and radioactivity-induced background rates similar to those from solar neutrinos. These unique properties, together with demonstrated stable operation over several years, allow for the exploration of new territory via high-sensitivity searches for a plethora of ultra-rare interactions. These include searches for particle dark matter, for second-order weak decays, and the observation of astrophysical neutrinos. We first review some properties of xenon as a radiation detection medium and the operation principles of dual-phase Xe-TPCs together with their energy calibration and resolution. We then discuss the status of currently running experiments and of proposed next-generation projects, describing some of the technological challenges. We end by looking at their sensitivity to dark matter candidates, to second-order weak decays and to solar and supernova neutrinos. Experiments based on dual-phase Xe-TPCs are difficult and, like all good experiments, they are constantly pushed to their limits. Together with many other endeavours in astroparticle physics and cosmology they will continue to push at the borders of the unknown, hopefully to reveal profound new knowledge about our cosmos. This article is part of the theme issue 'The particle-gravity frontier'.

Noise assessment of CMOS active pixel sensors for the CYGNO Experiment

Active Pixel sensors play a crucial role in enabling successful low-light scientific experiments due to their inherent advantages and capabilities. Such devices not only offer high spatial resolution but also feature individual pixels with integrated amplifiers, allowing for direct signal amplification at the pixel level. This results in reduced readout noise and improved signal-to-noise ratio (SNR), which are particularly vital when dealing with limited photon counts in low-light environments. This holds particularly true for scientific CMOS (sCMOS) sensors, acknowledged as an advanced evolution of Active Pixel sensors. However, despite their advantages, such sensors can still exhibit limitations such as higher cost and presence of noise artifacts that should be closely investigated. In particular, CYGNO project fits in a global effort aimed at direct detection of Dark Matter particles. CYGNO collaboration intends to build a detector based on a Time Projection Chamber making use of Gas Electron Multipliers for the amplification of ionization electrons. The GEM multiplication process produces photons that can be readout by a high-resolution sCMOS sensor. Such detection system is being designed to have enough sensitivity to detect low-energy particles and to measure released energy with enough granularity so to reconstruct direction and energy profile along their trajectories. The image sensor has an important role in the detector performance, having a direct impact on the SNR of the experiment. This work proposes a study on the performance of three different sCMOS sensors with respect to their sensitivity to low-energy particles and their intrinsic noise, which are of the utmost importance for various scientific experiments.

Characterisation of low background CaWO$_4$ crystals for CRESST-III

The CRESST-III experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei in a scintillating CaWO_44 target crystal. For many years CaWO_44 crystals have successfully been produced in-house at Technische Universität München with a focus on high radiopurity. To further improve the CaWO_44 crystals, an extensive chemical purification of the raw materials has been performed and the crystal TUM93 was produced from this powder. We present results from an \alphaα-decay rate analysis performed on 344 days of data collected in the ongoing CRESST-III data-taking campaign. The \alphaα-decay rate could significantly be reduced.

Observational constraints on interacting dark energy models with multiple measurements of quasars

Dark energy and dark matter, two subjects of basic physics, have received a lot of attention in the 21st century. From the observational point of view, the interaction between dark energy and dark matter can significantly affect cosmological distances. This gives rise to the possibility of indirectly detecting such interaction through high-redshift cosmological probes. Theoretically, the introduction of interaction between dark energy and dark matter can assist in alleviating the coincidence problem of the standard cosmological model ($\Lambda$CDM model). Furthermore, this can provide a new method of studying the properties of dark matter particles. In this paper, based on the latest observations of multiple measurements of quasars (X-ray+UV quasars acting as standard candles, compact radio quasars acting as standard rulers) covering the redshift range of $0.04~<~z~<~5.1$ and baryonic acoustic oscillation between ($0.38~<~z~<~2.34$), we investigate the observational constraints on a variety of interacting dark energy models ($\gamma_d~$IDE model, $\gamma_m~$IDE model) and other cosmological models ($\Lambda$CDM model, XCDM model). The results provide us with a quantitative analysis of the possible interaction between dark energy and dark matter, as well as the possible range of the mass of dark matter particles. The joint analysis shows that: (1) Multiple measurements of quasars can provide more stringent constraints on the interacting dark energy models, which can further strengthen the potential of quasars acting as effective cosmological standard probes at higher redshifts; (2) In the framework of both $\gamma_m$IDE model and $\gamma_d$IDE model, the quasar data supports possible conversion of dark energy into dark matter at high redshift, which alleviates the coincidence problem to some extent. We also found that the interaction term is of a small value, which demonstrates the negligible interaction between dark matter and dark energy; (3) In the framework of $\Lambda$CDM model, which has shown the best consistency with quasar data, the density parameter of matter in the Universe is constrained at $\Omega_~m=0.317^{+0.007}_{-0.007}$, with the best-fit Hubble constant $H_0=68.177^{+0.497}_{-0.505}$ at 68.3% confidence level. These findings are consistent with the recent microwave background radiation (CMB) measurements from the Planck satellite; (4) If dark matter in the Universe exists in the form of scalar-field dark matter with $Z_2$ symmetry, we obtain the range of the mass of dark matter particles as $56~{\rm~GeV}\lesssim~m_S\lesssim~63~{\rm~GeV}$ or $m_S\gtrsim450~{\rm~GeV}$, based on the dark energy-dark matter coupling term from multiple measurements of quasars. Such conclusions agree well with the latest experimental results aimed at the direct detection of dark matter particles.

Improving the Quality of CaWO4 Target Crystals for CRESST

The Cryogenic Rare Event Search with Superconducting Thermometers (CRESST) experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei in a scintillating CaWO_4 target crystal. The CaWO_4 crystal is operated together with a light detector at mK temperature and read out by a Transition Edge Sensor. For many years, CaWO_4 crystals have successfully been produced in-house at Technical University of Munich (TUM) with a focus on high radiopurity which is crucial to reduce background originating from radioactive contamination. In order to further improve the CaWO_4 crystals, an extensive chemical purification of the raw materials and the synthesised CaWO_4 powder has been performed. In addition, a temperature gradient simulation of the growth process and subsequently an optimisation of the growth furnace with the goal to reduce the intrinsic stress was carried out. We present results on the intrinsic stress in the CaWO_4 crystals and on the CaWO_4 powder radiopurity. A crystal grown from the purified material was installed in the current CRESST set-up. The detector is equipped with an instrumented holder which is used to measure the alpha decay rate of the crystal. We present a preliminary analysis showing a significantly reduced intrinsic background from natural decay chains.

Projected sensitivity of the LUX-ZEPLIN experiment to the two-neutrino and neutrinoless double β decays of Xe134

The projected sensitivity of the LUX-ZEPLIN (LZ) experiment to two-neutrino and neutrinoless double β decay of Xe134 is presented. LZ is a 10-tonne xenon time-projection chamber optimized for the detection of dark matter particles and is expected to start operating in 2021 at Sanford Underground Research Facility, USA. Its large mass of natural xenon provides an exceptional opportunity to search for the double β decay of Xe134, for which xenon detectors enriched in Xe136 are less effective. For the two-neutrino decay mode, LZ is predicted to exclude values of the half-life up to 1.7×1024 years at 90% confidence level (CL) and has a three-sigma observation potential of 8.7×1023 years, approaching the predictions of nuclear models. For the neutrinoless decay mode LZ, is projected to exclude values of the half-life up to 7.3×1024 years at 90% CL.Received 19 May 2021Accepted 19 November 2021DOI:https://doi.org/10.1103/PhysRevC.104.065501©2021 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasDouble beta decayNeutrinoless double beta decayProperties90 ≤ A ≤ 149TechniquesSpectrometers & spectroscopic techniquesNuclear PhysicsParticles & Fields

Characterization of an ultra-high purity NaI(Tl) crystal scintillator with the SABRE Proof-of-Principle detector

The SABRE experiment aims to detect the annual modulation of the dark matter interaction rate by means of ultra-high purity NaI(Tl) crystals. It focuses on the achievement of a very low background to carry out a model-independent and high sensitivity test of the long-standing DAMA result. SABRE has recently completed a Proof-of-Principle (PoP) phase at the Gran Sasso National Laboratory, devoted to assess the radiopurity of the crystals. The results on the radiopurity of a 3.4-kg NaI(Tl) crystal scintillator grown within the SABRE Collaboration and operated underground in the SABRE-PoP setup, will be reported and discussed. The amount of potassium content in the crystal, determined by direct counting of 40K, is found to be < 4.7 ppb at 90% CL. The average background rate in the 1-6 keV energy region of interest (ROI) is 1.20 ± 0.05 counts/day/kg/keV, which is, for the first time, comparable with DAMA/LIBRA-phasel. Our background model indicates that this rate is dominated by 210Pb, and that about half of this contamination is located in the PTFE reflector wrapped around the crystal. Ongoing developments aimed at a further reduction of radioactive contaminants in the crystal indicates that a background rate ≤ 0.3 counts/day/kg/keV in the ROI is within reach. This value represents a benchmark for the development of next-generation NaI(Tl) detector arrays for the direct detection of dark matter particles.

Precision gamma-ray constraints for sub-GeV dark matter models

The indirect detection of dark matter particles with mass below the GeV scale has recently received significant attention. Future space-borne gamma-ray telescopes, including All-Sky-ASTROGAM, AMEGO, and GECCO, will probe the MeV gamma-ray sky with unprecedented precision, offering an exciting test of particle dark matter in the MeV-GeV mass range. While it is typically assumed that dark matter annihilates into only one Standard Model final state, this is not the case for realistic dark matter models. In this work we analyze existing indirect detection constraints and the discovery reach of future detectors for the well-motivated Higgs and vector-portal models using our publicly-available code Hazma. In particular, we show how to leverage chiral perturbation theory to compute the dark matter self-annihilation cross sections into final states containing mesons, the strongly-interacting Standard Model dynamical degrees of freedom below the GeV scale. We find that future telescopes could probe dark matter self-annihilation cross sections orders of magnitude smaller than those presently constrained by cosmic microwave background, gamma-ray and terrestrial observations.

High sensitivity characterization of an ultrahigh purity NaI(Tl) crystal scintillator with the SABRE proof-of-principle detector

We present new results on the radiopurity of a 3.4-kg NaI(Tl) crystal scintillator operated in the SABRE proof-of-principle detector setup. The amount of potassium contamination, determined by the direct counting of radioactive $^{40}$K, is found to be $2.2\pm1.5$ ppb, lowest ever achieved for NaI(Tl) crystals. With the active veto, the average background rate in the crystal in the 1-6 keV energy region-of-interest (ROI) is $1.20\pm0.05$ counts/day/kg/keV, which is a breakthrough since the DAMA/LIBRA experiment. Our background model indicates that the rate is dominated by $^{210}$Pb and that about half of this contamination is located in the PTFE reflector. We discuss ongoing developments of the crystal manufacture aimed at the further reduction of the background, including data from purification by zone refining. A projected background rate lower than $\sim$0.2 counts/day/kg/keV in the ROI is within reach. These results represent a benchmark for the development of next-generation NaI(Tl) detector arrays for the direct detection of dark matter particles.

Probing cosmic-ray accelerated light dark matter with IceCube

The direct detection of particle dark matter through its scattering with nucleons is of fundamental importance to understand the nature of DM . In this work, we propose that the high-energy neutrino detectors like IceCube can be used to uniquely probe the DM-nucleon cross-section for high-energy DM of ∼ PeV, up-scattered by the high-energy cosmic rays. We derive for the first time strong constraints on the DM-nucleon cross-section down to ∼ 10−32 cm2 at this energy scale for sub-GeV DM candidates. Such independent probe at energy scale far exceeding other existing direct detection experiments can therefore provide useful insights complementary to other searches.

New era of dark matter particle detection

The astronomical evidence of the existence of dark matter is overwhelming. However, the physical nature of dark matter is still unknown. It is widely believed that dark matter is some kind of new particles beyond the standard model of particle physics. Alternative candidates include the massive compact halo objects such as primordial black holes. Among all these candidates, the class of so-called weakly interacting massive particles (WIMPs) is the most natural and well theoretically motivated one. The WIMP scenario can naturally explain the abundance of dark matter in the universe via a canonical thermal production mechanism. It also gives a practical way of detecting those particles via various kinds of particle physics experiments. The direct detection method measures the momentum exchange when a dark matter particle scatters off a nucleus. The sensitivities of direct detection increase remarkably during the past 30 years since it was first proposed in the 1980s. China has operated two direct detection experiments, the CDEX and PandaX experiments, in the Jinping underground laboratory. Through the efforts of all the direct detection experiments, including CDEX and PandaX, the current upper limit about the spin-independent scattering cross section between the dark matter particle and the nucleon reaches the level of 10⁻⁴⁷ cm² which is only about two orders of magnitude higher than the neutrino-induced background. Although no convincing signal has been detected yet, such null results can constrain severely many kinds of theoretical models of dark matter. Several experiments are upgrading now, with the goal of a fiducial detector mass of several tons, which are expected to further improve the direct detection sensitivities. The indirect detection method is to search for the annihilation or decay products of dark matter in cosmic rays and gamma-rays, which is complimentary to the direct detection. The main indirect detection experiments in operation include the alpha magnetic spectrometer and the calorimeter electron telescope on the International Space Station, the Fermi gamma-ray space telescope, and China’s dark matter particle explorer. Several anomalies have been reported by the indirect detection experiments, such as the positron excess, the excess of the total electron plus positron spectrum, the gamma-ray excess in the Galactic center region. Interpretations of these excesses are still in debate. Nevertheless, these anomalies offer us targets for further investigation with increased statistics and improved understanding of the astrophysical backgrounds. Both the direct detection and indirect detection experiments will have significantly upgrading in the coming years. Particularly, China’s PandaX experiment is currently building a 4-ton scale detector which is expected to start to operate in 2021. The long-term plan of the CDEX experiment is also a ton-scale detector for multi-purpose studies including the dark matter searches. For the indirect detection, the HERD payload onboard the Chinese Space Station is in the prototype phase, and the next generation very large area gamma-ray space telescope is under design. On the ground we are building the large high-altitude air shower observatory for high-sensitivity sky survey in the very high energy gamma-ray band. All these efforts will make China play a significant or even leading role in the campaign of dark matter detection. We are looking forward to the breakthroughs in the exploration of the nature of dark matter.

Geant4-based electromagnetic background model for the CRESST dark matter experiment

The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) dark matter search experiment aims for the detection of dark matter particles via elastic scattering off nuclei in mathrm {CaWO_4} crystals. To understand the CRESST electromagnetic background due to the bulk contamination in the employed materials, a model based on Monte Carlo simulations was developed using the Geant4 simulation toolkit. The results of the simulation are applied to the TUM40 detector module of CRESST-II phase 2. We are able to explain up to (68 pm 16),mathrm {%} of the electromagnetic background in the energy range between 1 and 40,mathrm {keV}.

Direct detection of dark matter particles by nonlinear effects in crystal vibrations

The energetic dark matter particles (EDP) of (4 + 1.5) x 1015 eV mass-energy propagating from the central region of the Milky Way galaxy (CMW) are directly detected with the help of half-inch ~10 MHz quartz vibrators. The spectra of acousto-electric vibrations of thin piezoelectric crystal are theoretically calculated, and a nonlinear effect of external frictional influence is taken into account. The EDP produce the changes in the spectra of vibrations under specific orientation of the crystallographic axes toward the CMW. The mechanism of EDP-crystal interaction may be associated with the gravitational influence of EDP and their quantum properties, such as matter waves. The EDP average energy density is 0.71 + 0.29 (GeV/cm3) near Earth, which agrees with the expectations and existing astrophysical bounds of dark matter density in the solar neighborhood. The EDP can transfer their momenta-energy to a media of propagation. The influences of EDP, or naviten, on vibrating atoms are detected from 10 different samples during 5 years. The micro-void tracks of EDP-particles are also observed in the vibrating plates of fuzzed quartz, which appear due to EDP decay inside solid media. The existence of EDP-particles is in agreement with recent detection of the ~1015 eV energy neutrinos from the CMW region.

Lyman α forest and non-linear structure characterization in Fuzzy Dark Matter cosmologies

Fuzzy Dark Matter (FDM) represents an alternative and intriguing description of the standard Cold Dark Matter (CDM) fluid, able to explain the lack of direct detection of dark matter particles in the GeV sector and to alleviate small scales tensions in the cosmic large-scale structure formation. Cosmological simulations of FDM models in the literature were performed either with very expensive high-resolution grid-based simulations of individual haloes or through N-body simulations encompassing larger cosmic volumes but resorting on significant approximations in the FDM non-linear dynamics to reduce their computational cost. With the use of the new N-body cosmological hydrodynamical code AX-GADGET, we are now able not only to overcome such numerical problems, but also to combine a fully consistent treatment of FDM dynamics with the presence of gas particles and baryonic physical processes, in order to quantify the FDM impact on specific astrophysical observables. In particular, in this paper we perform and analyse several hydrodynamical simulations in order to constrain the FDM mass by quantifying the impact of FDM on Lyman-$\alpha$ forest observations, as obtained for the first time in the literature in a N-body setup without approximating the FDM dynamics. We also study the statistical properties of haloes, exploiting the large available sample, to extract information on how FDM affects the abundance, the shape, and density profiles of dark matter haloes.

Impact of Sommerfeld enhancement on helium reionization via WIMP dark matter

Dark matter annihilation can have a strong impact on many astrophysical processes in the Universe. In the case of Sommerfeld-enhanced annihilation cross sections, the annihilation rates are enhanced at late times, thus enhancing the potential annihilation signatures. We here calculate the Sommerfeld-enhanced annihilation signatures during the epoch of helium reionization, the epoch where helium becomes fully ionized due to energetic photons. When considering the upper limits on the energy injection from the CMB, we find that the resulting abundance of He$^{++}$ becomes independent of the dark matter particle mass. The resulting enhancement compared to a standard scenario is thus 1-2 orders of magnitude higher. For realistic scenarios compatible with CMB constraints, there is no significant shift in the epoch of helium reionization, which is completed between redshifts $3$ and $4$. While it is thus difficult to disentangle dark matter annihilation from astrophysical contributions (active galactic nuclei), a potential detection of dark matter particles and its interactions using the Large Hadron Collider (LHC) would allow one to quantify the dark matter contribution.

Dark Matter Particle Explorer and Its First Results

The Dark Matter Particle Explorer (DAMPE) is China's first astronomical satellite dedicated to the indirect detection of dark matter particles and the study of high-energy astrophysics. It can measure high-energy electrons and gamma-rays up to 10 TeV with unprecedentedly high energy resolution and low background. Cosmic ray nuclei up to 100 TeV can also be measured. DAMPE was launched on December 17, 2015, and has been operating smoothly in space for more than two years since then. The first results about the precise measurements of the electron plus positron spectrum between 25 GeV and 4.6 TeV have been reported.

Sub-GeV dark matter detection with electron recoils in carbon nanotubes

Directional detection of Dark Matter particles (DM) in the MeV mass range could be accomplished by studying electron recoils in large arrays of parallel carbon nanotubes. In a scattering process with a lattice electron, a DM particle might transfer sufficient energy to eject it from the nanotube surface. An external electric field is added to drive the electron from the open ends of the array to the detection region. The anisotropic response of this detection scheme, as a function of the orientation of the target with respect to the DM wind, is calculated, and it is concluded that no direct measurement of the electron ejection angle is needed to explore significant regions of the light DM exclusion plot. A compact sensor, in which the cathode element is substituted with a dense array of parallel carbon nanotubes, could serve as the basic detection unit.

Cosmogenic production of tritium in dark matter detectors

The direct detection of dark matter particles requires ultra-low background conditions at energies below a few tens of keV. Radioactive isotopes are produced via cosmogenic activation in detectors and other materials and those isotopes constitute a background source which has to be under control. In particular, tritium is specially relevant due to its decay properties (very low endpoint energy and long half-life) when induced in the detector medium, and because it can be generated in any material as a spallation product. Quantification of cosmogenic production of tritium is not straightforward, neither experimentally nor by calculations. In this work, a method for the calculation of production rates at sea level has been developed and applied to some of the materials typically used as targets in dark matter detectors (germanium, sodium iodide, argon and neon); it is based on a selected description of tritium production cross sections over the entire energy range of cosmic nucleons. Results have been compared to available data in the literature, either based on other calculations or from measurements. The obtained tritium production rates, ranging from a few tens to a few hundreds of nuclei per kg and per day at sea level, point to a significant contribution to the background in dark matter experiments, requiring the application of specific protocols for target material purification, material storing underground and limiting the time the detector is on surface during the building process in order to minimize the exposure to the most dangerous cosmic ray components.