Detection Of Dark Matter Particles Research Articles

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.

Dark Matter Detection Using Helium Evaporation and Field Ionization.

We describe a method for dark matter detection based on the evaporation of helium atoms from a cold surface and their subsequent detection using field ionization. When a dark matter particle scatters off a nucleus of the target material, elementary excitations (phonons or rotons) are produced. Excitations which have an energy greater than the binding energy of helium to the surface can result in the evaporation of helium atoms. We propose to detect these atoms by ionizing them in a strong electric field. Because the binding energy of helium to surfaces can be below 1meV, this detection scheme opens up new possibilities for the detection of dark matter particles in a mass range down to 1 MeV/c^{2}.

Cosmogenic activation of materials

Experiments looking for rare events like the direct detection of dark matter particles, neutrino interactions or the nuclear double beta decay are operated deep underground to suppress the effect of cosmic rays. But, the production of radioactive isotopes in materials due to previous exposure to cosmic rays is a hazard when ultra-low background conditions are required. In this context, the generation of long-lived products by cosmic nucleons has been studied for many detector media and for other materials commonly used. Here, the main results obtained on the quantification of activation yields on the Earth’s surface will be summarized, considering both measurements and calculations following different approaches. The isotope production cross-sections and the cosmic ray spectrum are the two main ingredients when calculating this cosmogenic activation; the different alternatives for implementing them will be discussed. Activation that can take place deep underground mainly due to cosmic muons will be briefly commented too. Presently, the experimental results for the cosmogenic production of radioisotopes are scarce and discrepancies between different calculations are important in many cases, but the increasing interest on this background source which is becoming more and more relevant can help to change this situation.

Electroweak Kaluza-Klein dark matter

In models with universal extra dimensions (UED), the lightest Kaluza-Klein excitation of neutral electroweak gauge bosons is a stable, weakly interacting massive particle and thus is a candidate for dark matter thanks to Kaluza-Klein parity. We examine concrete model realizations of such dark matter in the context of non-minimal UED extensions. The boundary localized kinetic terms for the electroweak gauge bosons lead to a non-trivial mixing among the first Kaluza-Klein excitations of the SU(2)W and U(1)Y gauge bosons and the resultant low energy phenomenology is rich. We investigate implications of various experiments including low energy electroweak precision measurements, direct and indirect detection of dark matter particles and direct collider searches at the LHC. Notably, we show that the electroweak Kaluza-Klein dark matter can be as heavy as 2.4 TeV, which is significantly higher than 1.3 TeV as is indicated as an upper bound in the minimal UED model.

Probing Sub-GeV Dark Matter with Conventional Detectors.

The direct detection of dark matter particles with mass below the GeV scale is hampered by soft nuclear recoil energies and finite detector thresholds. For a given maximum relative velocity, the kinematics of elastic dark matter nucleus scattering sets a principal limit on detectability. Here, we propose to bypass the kinematic limitations by considering the inelastic channel of photon emission from bremsstrahlung in the nuclear recoil. Our proposed method allows us to set the first limits on dark matter below 500MeV in the plane of dark matter mass and cross section with nucleons. In situations where a dark-matter-electron coupling is suppressed, bremsstrahlung may constitute the only path to probe low-mass dark matter awaiting new detector technologies with lowered recoil energy thresholds.

Holographic Superconductivity in the Presence of Dark Matter: Basic Issues

The holographic approach to study strongly coupled superconductors in the presence of dark matter is reviewed. We discuss the influence of dark matter on the superconducting transition temperature of both s-wave and p-wave holographic superconductors. The upper critical field, coherence length, penetration depth of holographic superconductors as well as the metal-insulator transitions have also been analysed. Issues related to the validity of AdS/CFT correspondence for the description of superconductors studied in the laboratory and possible experiments directed towards the detection of dark matter are discussed. In doing so we shall compare our assumptions and assertions with those generally accepted in the elementary particle experiments aimed at the detection of dark matter particles. The superconductivity is a macroscopic quantum phenomenon 1 appearing in many condensed matter systems and characterized by the expulsion of the magnetic field and zero resistance state at sufficiently low temperature. The superconducting rings show quantization of magnetic flux. This is also true for vortices in the type two superconductors. A number of other quantum effects appear if the superconductor is in contact with normal metal (Andreev reflection) or other superconductors (Josephson effect). All these properties and phenomena are at the heart of numerous applications of superconductors. Zero resistivity state allows the construction and operation of powerful superconducting electromagnets for important scientific and medical applications. The superconducting quantum interference devices (SQUIDs) are the most sensitive magnetometers. SQUIDs allow for the precise measurements of the flux quantum � = h/2e, where e is the electron charge and h the Planck constant. These devices have been proposed and used in the search for the magnetic monopole; the elementary particle postulated 2 by Dirac in 1931. The search 3 for this elusive particle continues 4 , with the hope that it might address an important question of composition of dark matter 5 . According to standard theory of gravity based on Newtonian dynamics the explanation of many astrophysical observations require the existence of large amount of matter that cannot be seen with telescopes, and is thus termed dark matter. The Planck satellite mission reveals that dark matter constitutes 26.8% of the total mass of the Universe, while ordinary matter makes only 4.9% of it. The rest 6 is the mysterious dark energy, 68.3%.

Results and strategies in dark matter detection

The dark matter (DM) parallel session DM2 of the 14th Marcel Grossmann Meeting was enriched by several contributions about the results and the strategies in the study and in the detection of DM particles in the Galactic halo. In the following, an overview of the latest results in this field will be summarized. A particular care will be given to the results obtained by exploiting the model independent DM annual modulation signature for the presence of DM particles in the galactic halo. Results from the other experiments using different procedures, different techniques and different target materials will be shortly addressed as well as implications and experimental perspectives.

Exploring Low-Mass Dark Matter with CRESST

The CRESST-II (Cryogenic Rare Event Search with Superconducting Thermometers) experiment, whose second phase has been successfully finished in summer 2015, aims at the direct detection of dark matter particles. The intrinsic radiopurity of CaWO $$_4$$ crystals, the capability to reject recoil events from alpha-surface contamination, and the energy threshold were significantly improved compared to previous runs of the experiment. A moderate exposure of 29 kg-days acquired by one $$\sim $$ 250 g CaWO $$_4$$ detector provides competitive limits on the spin-independent dark matter particle-nucleon cross section and probes a new region of parameter space for dark matter particle masses below 3 GeV/c $$^2$$ . The potential for low-mass dark matter particle search can be further exploited by a new detector design planned for CRESST-III. We describe the experimental strategy for the near future and give projections for the sensitivity.

Single event effect hardness for the front-end ASICs in the DAMPE satellite BGO calorimeter**Supported by Strategic Priority Research Program on Space Science of the Chinese Academy of Sciences (XDA04040202-4) and Fundamental Research Funds for the Central Universities (WK2030040048)

The Dark Matter Particle Explorer (DAMPE) is a Chinese scientific satellite designed for cosmic ray studies with a primary scientific goal of indirect detection of dark matter particles. As a crucial sub-detector, the BGO calorimeter measures the energy spectrum of cosmic rays in the energy range from 5 GeV to 10 TeV. In order to implement high-density front-end electronics (FEE) with the ability to measure 1848 signals from 616 photomultiplier tubes on the strictly constrained satellite platform, two kinds of 32-channel front-end ASICs, VA160 and VATA160, are customized. However, a space mission period of more than 3 years makes single event effects (SEEs) become threats to reliability. In order to evaluate SEE sensitivities of these chips and verify the effectiveness of mitigation methods, a series of laser-induced and heavy ion-induced SEE tests were performed. Benefiting from the single event latch-up (SEL) protection circuit for power supply, the triple module redundancy (TMR) technology for the configuration registers and the optimized sequential design for the data acquisition process, 52 VA160 chips and 32 VATA160 chips have been applied in the flight model of the BGO calorimeter with radiation hardness assurance.

A Global Analysis of Light and Charge Yields in Liquid Xenon

We present an updated model of light and charge yields from nuclear recoils in liquid xenon with a simultaneously constrained parameter set. A global analysis is performed using measurements of electron and photon yields compiled from all available historical data, as well as measurements of the ratio of the two. These data sweep over energies from 1 - 300 keV and external applied electric fields from 0 - 4060 V/cm. The model is constrained by constructing global cost functions and using a simulated annealing algorithm and a Markov Chain Monte Carlo approach to optimize and find confidence intervals on all free parameters in the model. This analysis contrasts with previous work in that we do not unnecessarily exclude data sets nor impose artificially conservative assumptions, do not use spline functions, and reduce the number of parameters used in NEST v0.98. We report our results and the calculated best-fit charge and light yields. These quantities are crucial to understanding the response of liquid xenon detectors in the energy regime important for rare event searches such as the direct detection of dark matter particles.

Progresses in the study of the nature of dark matter and detections

Astrophysical observations have indicated that dark matter contributes to 85% of the energy budeget of the Universe, but its nature is still largely unknown. Understanding the nature of dark matter requires new physics beyond the current standard models of particle physics. This article briefly reviews the evidence, origins of relic aboundance and candidates of dark matter, with the focus on the indirect and direct detection of dark matter particles. The recent experimental progresses are briefly discussed. Some mechanisims and models such as the Sommerfeld enhancements, effective operator approach and the isospin violating dark matter are discussed.

Results from the LUX dark matter experiment

The LUX (Large Underground Xenon) experiment aims at the direct detection of dark matter particles via their collisions with xenon nuclei. The 370kg two-phase liquid xenon time projection chamber measures simultaneously the scintillation and ionization from interactions in the target. The ratio of these two signals provides very good discrimination between potential nuclear recoil and electronic recoil signals to search for WIMP-nucleon scattering. The LUX detector operates at the Sanford Underground Research Facility (Lead, South Dakota, USA) since February 2013. First results were presented in late 2013 setting the world׳s most stringent limits on WIMP-nucleon scattering cross-sections over a wide range of WIMP masses. A 300 day run beginning in 2014 will further improve the sensitivity and new calibration techniques will reduce systematics for the WIMP signal search.

Indirect searches for dark matter

Abstract The indirect detection of particle dark matter (DM) is based on the search for anomalous components in cosmic rays (CRs) due to the annihilation of DM pairs in the galactic halo, on the top of the standard astrophysical production. We revise here the most recent results on the DM searches for γ -rays, antiprotons, antideuterons and positrons in CRs.

Millisecond pulsar interpretation of the Galactic center gamma-ray excess

It was found in the Fermi-LAT data that there is an extended γ-ray excess in the Galactic center region. The proposed sources to be responsible for the excess include dark matter annihilation or an astrophysical alternative from a population of millisecond pulsars (MSPs). Whether or not the MSP scenario can explain the data self-consistently has very important implications for the detection of particle dark matter, which is however, subject to debate in the literature. In this work we study the MSP scenario in detail, based on the detected properties of the MSPs by Fermi-LAT. We construct a model of Milky Way disk-component MSPs which can reproduce the γ-ray properties of the observed Fermi-LAT MSPs, and derive the intrinsic luminosity function of the MSPs. The model is then applied to a bulge population of MSPs. We find that the extended γ-ray excess can be well explained by the bulge MSPs without violating the detectable flux distribution of MSPs by Fermi-LAT. The spatial distribution of the bulge MSPs as implied by the distribution of low mass X-ray binaries follows a r−2.4 profile, which is also consistent with the γ-ray excess data. We conclude that the MSP model can explain the Galactic center γ-ray excess self-consistently, satisfying all the current observational constraints.

Antihelium from dark matter

Cosmic-ray antinuclei provide a promising discovery channel for the indirect detection of particle dark matter. Hadron showers produced by the pair annihilation or decay of Galactic dark matter generate antinucleons which can in turn form light antinuclei. Previous studies have only focused on the spectrum and flux of low energy antideuterons which, although very rarely, are occasionally also produced by cosmic-ray spallation. Heavier elements ($A\ensuremath{\ge}3$) have instead entirely negligible astrophysical background and a primary yield from dark matter which could be detectable by future experiments. Using a Monte Carlo event generator and an event-by-event phase space analysis, we compute, for the first time, the production spectrum of $^{3}\overline{\mathrm{He}}$ and $^{3}\overline{\mathrm{H}}$ for dark matter annihilating or decaying to $b\overline{b}$ and ${W}^{+}{W}^{\ensuremath{-}}$ final states. We then employ a semianalytic model of interstellar and heliospheric propagation to calculate the $^{3}\overline{\mathrm{He}}$ flux as well as to provide tools to relate the antihelium spectrum corresponding to an arbitrary antideuteron spectrum. Finally, we discuss prospects for current and future experiments, including GAPS and AMS-02.

Dark Matter Particle Detection System SQUID - Magnetic Calorimeter

Physical principles underlying the concept of the Dark Matter (DM) are considered. Problems of Dark Matter particle detection are briefly reviewed. An original two-channel scheme for direct detection of cosmic DM particles is proposed. It is based on a super-low-temperature calorimeter and includes a nuclear spin system whose magnetic response is measured by a quantum interferometer (SQUID). Low threshold and the capability for efficiently suppressing the recoil-electron background are the most important advantages of the proposed scheme. They make it possible to detect DM particles with extremely low recoil energies and carry out direct DM search with high sensitivity.

Three puzzles from nuclear astrophysics

I discuss three open problems in astrophysics where nuclear physics can make important contributions: the solar abundance problem, dark matter particle detection and the origin of the r-process elements.