Search

Abstract $$\varLambda $$ Λ -Cold Dark Matter ( $$\varLambda $$ Λ CDM) has been successful at explaining the large-scale structures in the universe but faces severe issues on smaller scales when compared to observations. Introducing self-interactions between dark matter particles claims to provide a solution to the small-scale issues in the $$\varLambda $$ Λ CDM simulations while being consistent with the observations at large scales. The existence of the energy region in which these self-interactions between dark matter particles come close to saturating the S-wave unitarity bound can result in the formation of dark matter bound states called darkonium. In this scenario, all the low energy scattering properties are determined by a single parameter, the inverse scattering length $$\gamma $$ γ . In this work, we set bounds on $$\gamma $$ γ by studying the impact of darkonium on the observations at direct detection experiments using data from CRESST-III and XENON1T. The exclusion limits on $$\gamma $$ γ are then subsequently converted to exclusion limits on the self-interaction cross-section and compared with the constraints from astrophysics and N-body simulations.

Abstract In recent times, the sensitivity of low-mass direct dark matter searches has been limited by unknown low energy backgrounds close to the energy threshold of the experiments known as the low energy excess (LEE). The CRESST experiment utilises advanced cryogenic detectors constructed with different types of crystals equipped with Transition Edge Sensors (TESs) to measure signals of nuclear recoils induced by the scattering of dark matter particles in the detector. In CRESST, this low energy background manifests itself as a steeply rising population of events below 200 eV. A novel detector design named doubleTES using two identical TESs on the target crystal was studied to investigate the hypothesis that the events are sensor-related. We present the first results from two such modules, demonstrating their ability to differentiate between events originating from the crystal’s bulk and those occurring in the sensor or in its close proximity.

Abstract Cryogenic scintillating calorimeters are ultra- sensitive particle detectors for rare event searches, particularly for the search for dark matter and the measurement of neutrino properties. These detectors are made from scintillating target crystals generating two signals for each particle interaction. The phonon (heat) signal precisely measures the deposited energy independent of the type of interacting particle. The scintillation light signal yields particle discrimination on an event-by-event basis. This paper presents a likelihood framework modeling backgrounds and a potential dark matter signal in the two-dimensional plane spanned by phonon and scintillation light energies. We apply the framework to data from CaWO $$_4$$ 4 -based detectors operated in the CRESST dark matter search. For the first time, a single likelihood framework is used in CRESST to model the data and extract results on dark matter in one step by using a profile likelihood ratio test. Our framework simultaneously fits (neutron) calibration data and physics (background) data and allows combining data from multiple detectors. Although tailored to CaWO $$_4$$ 4 -targets and the CRESST experiment, the framework can easily be expanded to other materials and experiments using scintillating cryogenic calorimeters for dark matter search and neutrino physics.

Abstract COSINUS is a dark matter (DM) direct search experiment that uses sodium iodide (NaI) crystals as cryogenic calorimeters. Thanks to the low nuclear recoil energy threshold and event-by-event discrimination capability, COSINUS will address the long-standing DM claim made by the DAMA/LIBRA collaboration. The experiment is currently under construction at the Laboratori Nazionali del Gran Sasso, Italy, and employs a large cylindrical water tank as a passive shield to meet the required background rate. However, muon-induced neutrons can mimic a DM signal therefore requiring an active veto system, which is achieved by instrumenting the water tank with an array of photomultiplier tubes (PMTs). This study optimizes the number, arrangement, and trigger conditions of the PMTs as well as the size of an optically invisible region. The objective was to maximize the muon veto efficiency while minimizing the accidental trigger rate due to the ambient and instrumental background. The final configuration predicts a veto efficiency of 99.63 ± 0.16% and 44.4 ± 5.6% in the tagging of muon events and showers of secondary particles, respectively. The active veto will reduce the cosmogenic neutron background rate to 0.11 ± 0.02 cts $$\cdot $$ · kg $$^{-1}\cdot $$ - 1 · year $$^{-1},$$ - 1 , corresponding to less than one background event in the region of interest for the whole COSINUS-1 $$\pi $$ π exposure of 1000 kg $$\cdot $$ · days.

Abstract Diamond operated as a cryogenic calorimeter is an excellent target for direct detection of low-mass dark matter candidates. Following the realization of the first low-threshold cryogenic detector that uses diamond as absorber for astroparticle physics applications, we now present the resulting exclusion limits on the elastic spin-independent interaction cross-section of dark matter with diamond. We measured two 0.175 g CVD (Chemical Vapor Deposition) diamond samples, each instrumented with a Transition Edge Sensor made of Tungsten (W-TES). Thanks to the energy threshold of just 16.8 eV of one of the two detectors, we set exclusion limits on the elastic spin-independent interaction of dark matter particles with carbon nuclei down to dark matter masses as low as 0.122 GeV/c $$^2$$ 2 . This work shows the scientific potential of cryogenic detectors made from diamond and lays the foundation for the use of this material as target for direct detection dark matter experiments.

Abstract CRESST is one of the most prominent direct detection experiments for dark matter particles with sub-GeV/c $$^2$$ 2 mass. One of the advantages of the CRESST experiment is the possibility to include a large variety of nuclides in the target material used to probe dark matter interactions. In this work, we discuss in particular the interactions of dark matter particles with protons and neutrons of $$^{6}$$ 6 Li. This is now possible thanks to new calculations on nuclear matrix elements of this specific isotope of Li. To show the potential of using this particular nuclide for probing dark matter interactions, we used the data collected previously by a CRESST prototype based on LiAlO $$_2$$ 2 and operated in an above ground test-facility at Max-Planck-Institut für Physik in Munich, Germany. In particular, the inclusion of $$^{6}$$ 6 Li in the limit calculation drastically improves the result obtained for spin-dependent interactions with neutrons in the whole mass range. The improvement is significant, greater than two order of magnitude for dark matter masses below 1 GeV/c $$^2$$ 2 , compared to the limit previously published with the same data.

Abstract The COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) experiment aims at the detection of dark matter-induced recoils in sodium iodide (NaI) crystals operated as scintillating cryogenic calorimeters. The detection of both scintillation light and phonons allows performing an event-by-event signal to background discrimination, thus enhancing the sensitivity of the experiment. The choice of using NaI crystals is motivated by the goal of probing the long-standing DAMA/LIBRA results using the same target material. The construction of the experimental facility is foreseen to start by 2021 at the INFN Gran Sasso National Laboratory (LNGS) in Italy. It consists of a cryostat housing the target crystals shielded from the external radioactivity by a water tank acting, at the same time, as an active veto against cosmic ray-induced events. Taking into account both environmental radioactivity and intrinsic contamination of materials used for cryostat, shielding and infrastructure, we performed a careful background budget estimation. The goal is to evaluate the number of events that could mimic or interfere with signal detection while optimising the geometry of the experimental setup. In this paper we present the results of the detailed Monte Carlo simulations we performed, together with the final design of the setup that minimises the residual amount of background particles reaching the detector volume.

Abstract In this work, a first cryogenic characterization of a scintillating $$\hbox {LiAlO}_{2}$$ LiAlO 2 single crystal is presented. The results achieved show that this material holds great potential as a target for direct dark matter search experiments. Three different detector modules obtained from one crystal grown at the Leibniz-Institut für Kristallzüchtung (IKZ) have been tested to study different properties at cryogenic temperatures. Firstly, two 2.8 g twin crystals were used to build different detector modules which were operated in an above-ground laboratory at the Max Planck Institute for Physics (MPP) in Munich, Germany. The first detector module was used to study the scintillation properties of $$\hbox {LiAlO}_{2}$$ LiAlO 2 at cryogenic temperatures. The second achieved an energy threshold of ( $$213.02\pm 1.48$$ 213.02 ± 1.48 ) eV which allows setting a competitive limit on the spin-dependent dark matter particle-proton scattering cross section for dark matter particle masses between $$350\,\hbox {MeV/c}^{2}$$ 350 MeV/c 2 and $$1.50\,\hbox {GeV/c}^{2}$$ 1.50 GeV/c 2 . Secondly, a detector module with a 373 g $$\hbox {LiAlO}_{2}$$ LiAlO 2 crystal as the main absorber was tested in an underground facility at the Laboratori Nazionali del Gran Sasso (LNGS): from this measurement it was possible to determine the radiopurity of the crystal and study the feasibility of using this material as a neutron flux monitor for low-background experiments.

Abstract 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 $$\mathrm {CaWO_4}$$ CaWO4 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 $$(68 \pm 16)\,\mathrm {\%}$$ (68±16)% of the electromagnetic background in the energy range between 1 and $$40\,\mathrm {keV}$$ 40keV .

Abstract In this work, we want to highlight the potential of lithium as a target for spin-dependent dark matter search in cryogenic experiments, with a special focus on the low-mass region of the parameter space. We operated a prototype detector module based on a $$\hbox {Li}_2\hbox {MoO}_4$$ Li2MoO4 target crystal in an above-ground laboratory. Despite the high background environment, the detector sets a competitive limit on spin-dependent interactions of dark matter particles with protons and neutrons for masses between $$0.8~\hbox {GeV/c}^2$$ 0.8GeV/c2 and $$1.5~\hbox {GeV/c}^2$$ 1.5GeV/c2 .

Abstract CRESST is a direct dark matter search experiment, aiming for an observation of nuclear recoils induced by the interaction of dark matter particles with cryogenic scintillating calcium tungstate crystals. Instead of confining ourselves to standard spin-independent and spin-dependent searches, we re-analyze data from CRESST-II using a more general effective field theory (EFT) framework. On many of the EFT coupling constants, improved exclusion limits in the low-mass region (< 3–4 GeV/$$c^2$$ c2 ) are presented.

The original version of this article unfortunately contains mistakes.

The effect of toxic element multicontamination on photosynthetic responses was observed in a greenhouse hydroponic culture of lettuce plants (Lactuca sativa var. capitata). The experiment focused only on the combined effect of selected toxic elements without the influence of soil, due to the hydroponic conditions. Pre-cultivated (six-true-leaf stage) plants were grown in control and contaminated hydroponic culture for 14 d. The mix of toxic elements (As, Cd, Pb, and Zn) in the contaminated solution corresponded to the water-soluble fraction of soil from the anthropogenically contaminated Litavka River area, Czech Republic. The plant response was measured by determining the toxic element contents, dry biomass, and gas-exchange parameters. Lettuce accumulated toxic elements predominantly in the roots, with low translocation to the leaves. The uptake of toxic elements harmed photosynthesis and caused a decrease in net photosynthetic rate, transpiration rate, and stomatal conductance. Consequently, the whole dry biomass of the plants decreased. The results show that contamination in hydroponic conditions had an irreversible effect on plant fitness due to direct contact between the roots and contaminated solutions.

The present study investigated the effect of arsenic (As) on photosynthesis and other selected physiological parameters in two ferns. The ferns (Pteris cretica 'Albo-lineata' and 'Parkerii') subjected to As doses of 100 and 250 mg kg-1 for three months, showed different As accumulation, which was higher in Albo-lineata. Overall, the obtained results indicated significant differences between studied ferns. The individual effects of As and growing period on all parameters were very variable. However, As doses generally caused a decrease of net photosynthetic rate, stomatal conductance, transpiration rate, maximum quantum yield of PSII, and photosynthetic pigments. The sampling period effect was significant for magnesium content of Parkerii (decrease) and contents of photosynthetic pigments of Albo-lineata (increase) and Parkerii (decrease). Results showed that Parkerii had higher sensitivity to As doses than Albo-lineata, which was also reflected by the higher free glycine content and its increase by As doses.

In this paper, we focused on a problem of authentication on low-cost devices. We have proposed a new light-weight protocol for mutual authentication of communication entities with non-repudiation of realized events. The protocol is simple and suitable for implementation on low-cost devices. Non-repudiation of realized events is achieved by involving a Trusted Third Party (TTP) to the communication. The proposed protocol uses only an appropriate lightweight hash function and pre-shared secret data. Security of the proposed protocol was verified by the BAN (Burrows-Abadi-Needham) logic.

Power analysis presents the typical example of successful attacks against trusted cryptographic devices such as RFID (Radio-Frequency IDentifications) and contact smart cards. In recent years, the cryptographic community has explored new approaches in power analysis based on machine learning models such as Support Vector Machine (SVM), RF (Random Forest) and Multi-Layer Perceptron (MLP). In this paper, we made an extensive comparison of machine learning algorithms in the power analysis. For this purpose, we implemented a verification program that always chooses the optimal settings of individual machine learning models in order to obtain the best classification accuracy. In our research, we used three datasets, the first containing the power traces of an unprotected AES (Advanced Encryption Standard) implementation. The second and third datasets are created independently from public available power traces corresponding to a masked AES implementation (DPA Contest v4). The obtained results revealed some interesting facts, namely, an elementary k-NN (k-Nearest Neighbors) algorithm, which has not been commonly used in power analysis yet, shows great application potential in practice.

Changes of amino acid (AAs) contents (glutamic acid - Glu, aspartic acid - Asp) and fatty acids profile (FAs) in spinach under cadmium (Cd) soil contamination (Cd1 = 30, Cd2 = 60, Cd3 = 90 mg/kg soil) are reported here. Spinach plants were sampled 25, 40, 55 and 75 days after sowing. Growing Cd soil contamination was associated with the strong inhibition of above-ground biomass (23.5-6.3 g dry matter per pot) and with the enhancement of Cd content (0.60-72.38 mg/kg dry matter) in leaves. During 55 days of plant growing the increase of Glu and Asp content was associated with the enhancement of Cd content. The highest accumulation of AAs was determined on Cd3 treatment after 55 days of cultivation. Strong decreases of both AAs were confirmed in the last sampling period for Cd treatments (reduction of Glu content of Cd3 treatment to ca. 64% and Asp content to ca. 72% in contrast to control). The content of saturated fatty acids increased (mainly palmitic acid) and the content of unsaturated fatty acids decreased in spinach aboveground biomass with increasing Cd concentration. Results of multivariate analysis of variance MANOVA showed the significant effect of Cd contamination for FAs metabolism, but the most significant effect was confirmed for plant growing period.

Noccaea caerulescens (NC) and Arabidopsis halleri (AH) were studied to compare cadmiunm (Cd) accumulation and resistance. After 30, 60 and 90 days of plant cultivation in Cd contaminated soil (Cd1 = 30, Cd2 = 60 and Cd3 = 90 mg Cd/kg soil) amino acids were determined in plants. The comparison between both species showed that Cd stress resulted in different changes of amino acids levels playing a significant role in plant adaptation to Cd stress. Our analyses indicated higher accumulations of amino acids in the roots of NC compared to AH. Contrasting responses of plants to Cd contamination were confirmed in methionine metabolism. Methionine was determined only in roots of AH after 30 and 60 days of plant cultivation. Free methionine content decreased with increasing Cd contamination (Cd3 treatment - 40% decrease compared to the control treatment). Our results also showed that NC contains more than 10-fold higher content of histidine than AH. These observations indicated that this amino acid may be involved in Cd resistance and accumulation by reducing oxidative damage. Tryptophan plays a major role in the regulation of plant development and in defense responses. Its significant increase for NC treatments in contrast to AH treatments was determined.

Changes of free amino acid (AA) contents (glutamic acid, glutamine, aspartic acid, asparagines, proline, hydroxyproline) in Noccaea caerulescens and Arabidopsis halleri under cadmium soil contamination (Cd1 = 30, Cd2 = 60, Cd3 = 90 mg/kg soil) are reported. Results of the pot experiment confirmed different effect of Cd on N. caerulescens in contrast to A. halleri and the higher stress adaptation of A. halleri. Total free AA contents in both plant species were not significantly modified by Cd contamination. The glutamic acid and glutamate contents in plant biomass were decreased under Cd2 and Cd3 stress. The declines of contents of both AA can be caused by intensive syntheses of plant defense elicitors, but declines in A. halleri were significantly lower in contrast to N. caerulescens. The content of aspartic acid was increased in N. caerulescens under Cd stress, but in A. halleri its changes were not observed. The different pathways of nitrogen utilization of tested plants were confirmed: the major AA forms used for nitrogen transport are glutamate for N. caerulescens and asparagine for A. halleri. The increase of proline content was determined only in N. caerulescens growing under Cd stress in the beginning of growing period.

This paper describes an innovative method of the power analysis which presents the typical example of successful attacks against trusted cryptographic devices such as RFID (Radio-Frequency IDentifications) and contact smart cards. The proposed method analyzes power consumption of the AES (Advanced Encryption Standard) algorithm with neural network, which successively classifies the first byte of the secret key. This way of the power analysis is an entirely new approach and it is designed to combine the advantages of simple and differential power analysis. In the extreme case, this feature allows to determine the whole secret key of a cryptographic module only from one measured power trace. This attribute makes the proposed method very attractive for potential attackers. Besides theoretical design of the method, we also provide the first implementation results. We assume that the method will be certainly optimized to obtain more accurate classification results in the future.

The aim of this study was to evaluate metals (Cd, Cu, Pb and Zn) sorption behavior after biochar application into a metal-contaminated soil. Additionally, two different types of biochar originated from the same organic material (contaminated and uncontaminated) at different application rates (1% and 2% w/w) were evaluated as a novelty of the experiment. Batch sorption/desorption experiments were established to compare the sorption behavior of metals originating from single- and multi-element solutions. Zinc as one of the main contaminants in the studied soil was easily desorbed in the presence of Cu, Pb and to a lesser extent by Cd. This desorption was reduced after biochar application. The obtained results proved the different sorption behavior of metals in the single-metal solution compared to the multi-metal ones due to competition effect. Moreover, during multi-element sorption, Zn was significantly desorbed. The applied biochar enhanced Cu and Pb sorption and no changes were observed when contaminated and uncontaminated biochar was used. Furthermore, the application rate (1% and 2% w/w) had no effect as well. In summary, it is needed to point out that the applied rates of biochars were insufficient for metal immobilization in such contaminated soils.

A novel second-generation current conveyor is defined. A special three-port cell containing the above element is presented. A method for nth-order multifunction circuit realization is described. Two universal networks illustrate the described procedure.

Two novel autonomous networks containing current conveyors are presented. The design of second-order oscillators and frequency filters based on the above general networks is described. The Q-factor of the circuits designed is controllable through a grounded single resistor. Some examples illustrate the procedure described. Two new one-port elements for high-order immittance realization are shown.

The paper deals with the design of floating one- and/or two-port high-order networks. The current conveyor CCII+ seems to be a suitable active building block for this purpose. Some examples of the above mentioned networks are shown .

The CRESST experiment observes an unexplained excess of events at low energies. In the current CRESST-III data-taking campaign we are operating detector modules with different designs to narrow down the possible explanations. In this work, we show first observations of the ongoing measurement, focusing on the comparison of time, energy and temperature dependence of the excess in several detectors. These exclude dark matter, radioactive backgrounds and intrinsic sources related to the crystal bulk as a major contribution.

NaI(Tl) based scintillation detectors have become a staple in the field of direct dark matter searches, with the DAMA-LIBRA experiment being the standout for its reported observation of an annually modulating WIMP-like signal which is in direct contrast with other results. In order to accurately calibrate the energies of WIMP-induced nuclear recoil signals, precise measurements of the quenching factor of the NaI crystals are essential for each of these experiments, as it is well established that electron recoils and nuclear recoils have dissimilar scintillation light yields. In this contribution, we present first preliminary results of an ongoing systematic study that has been carried out by the COSINUS collaboration and Duke University to measure the quenching factor of Na recoils. Five ultra-pure NaI crystals, manufactured by the Shanghai Institute for Ceramics, each of which have varying Tl dopant concentrations, were irradiated with a mono-energetic neutron beam at the Triangle Universities National Laboratory, North Carolina, USA to extract the quenching factor values in the low recoil energies of 1-30keV$_{nr}$.

The CRESST-III experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei in a scintillating CaWO$_4$ target crystal. For many years CaWO$_4$ crystals have successfully been produced in-house at Technische Universität München with a focus on high radiopurity. To further improve the CaWO$_4$ 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 $\alpha$-decay rate analysis performed on 344 days of data collected in the ongoing CRESST-III data-taking campaign. The $\alpha$-decay rate could significantly be reduced.

For over twenty-five years the DAMA/LIBRA experiment has reported an annual modulation signal that is consistent with a dark matter explanation. This signal is, currently, in tension with the null results observed by other searches that utilize different target detectors. The COSINUS experiment will perform a model-independent cross-check of the DAMA/LIBRA result by using the same target material, NaI crystals, operated as scintillating calorimeters. By measuring both temperature and light the NaI crystals in COSINUS will be able to distinguish between electron and nuclear recoils on an event-by-event basis. However, background events induced by cosmic-rays, environmental radioactivity or the intrinsic contamination of the materials used in the crystal, shielding and infrastructure can pose an issue to any analysis and must be fully understood. We report on the status of the development of the simulation for an active water Cherenkov muon veto, as well as the results of the beginning radiogenic material screening.

The increasing statistical significance of the DAMA/LIBRA annual modulation signal is a cause for tension in the field of dark matter direct detection. The COSINUS experiment aims at a model-independent cross-check of the DAMA/LIBRA signal claim, using NaI crystals operated as cryogenic scintillating calorimeters at millikelvin temperatures. Such a setup enables measurement of phonon and scintillation light signals via Transition Edge Sensors (TESs) and allows particle discrimination on an event-by-event basis. The non-standard properties of NaI cause an obstacle when attaching a TES directly onto the surface of the crystal. This can be overcome with the ``remoTES'' design, where the TES is attached to an external wafer crystal. We present the results from a first successful operation of NaI and other crystals as cryogenic calorimeters with the remoTES design.

Many low-threshold experiments observe sharply rising event rates of yet unknown origins below a few hundred eV, and larger than expected from known backgrounds. Due to the significant impact of this excess on the dark matter or neutrino sensitivity of these experiments, a collective effort has been started to share the knowledge about the individual observations. For this, the EXCESS Workshop was initiated. In its first iteration in June 2021, ten rare event search collaborations contributed to this initiative via talks and discussions. The contributing collaborations were CONNIE, CRESST, DAMIC, EDELWEISS, MINER, NEWS-G, NUCLEUS, RICOCHET, SENSEI and SuperCDMS. They presented data about their observed energy spectra and known backgrounds together with details about the respective measurements. In this paper, we summarize the presented information and give a comprehensive overview of the similarities and differences between the distinct measurements. The provided data is furthermore publicly available on the workshop’s data repository together with a plotting tool for visualization.