Status of low mass WIMP detector TREX-DM

TREX-DM (TPC Rare Event eXperiment for Dark Matter) is a high-pressure Micromegas-based TPC designed to host a few hundreds of grams of light nuclei (argon or neon) with energy thresholds potentially at the level of 0.4 keVee or below. Preliminary background studies suggest that the levels expected are of the order of 1-10 counts keV-1 kg-1 d-1, making TREX-DM competitive in the search for low mass WIMPs (<10 GeV). The experiment has been approved by the LSC (Laboratorio Subterrneo de Canfranc) and the last months have been devoted to its installation underground. Here we will report on the first commissioning phase

The TREX-DM experiment at the Canfranc Underground Laboratory

TREX-DM (TPC Rare Event eXperiment for Dark Matter) is intended to look for low mass WIMPs in the Canfranc Underground Laboratory (LSC) in Spain, using light elements (Ne, Ar) as target in a high pressure TPC equipped with Micromegas readouts. Here, a description of the detector, the first results from commissioning data and the expected sensitivity from the developed background model are briefly presented

Microbulk Micromegas in non-flammable mixtures of argon and neon at high pressure

We report on a systematic characterization of microbulk Micromegas readouts in high-pressure Ar+1%iC4H10 and Ne+2%iC4H10 mixtures. Experimental data on gain, electron transmission and energy resolution are presented for a wide range of drift and amplification voltages and pressures from 1 bar to 10 bar for argon and from 5 bar to 10 bar in neon, in steps of 1 bar. Maximum gains higher than 1.7e3 (1.7e4) in argon (neon) are measured for all pressures, remarkably without the significant decrease with pressure typically observed in other amplification structures. A competitive energy resolution at 22.1 keV, but with a slight degradation with pressure, is observed:from 10.8% at 1 bar to 15.6% FWHM at 10 bar in argon and from 8.3% at 5 bar to 15.0% FWHM at1 10 bar in neon. The experimental setup, procedure and the results will be presented and discussed in detail. The work is motivated by the TREX-DM experiment, that is operating in the Laboratorio Subterr\'aneo de Canfranc with the mentioned mixtures, although the results may be of interest for other applications of time projection chambers at high pressures.Comment: 11 pages, 8 figures, prepared for JINST, minor changes in th text, added a referenc

Status of the TREX-DM experiment at the Canfranc Underground Laboratory

The TREX-DM experiment is conceived to look for low mass WIMPs by means of a gas time projection chamber equipped with novel micromegas readout planes at the Canfranc Underground Laboratory. The detector can hold 20 l of pressurized gas up to 10 bar, which corresponds to 0.30 kg of Ar, or alternatively, 0.16 kg of Ne. The micromegas will be read with a self-triggered acquisition, allowing for effective thresholds below 0.4 keV (electron equivalent). The preliminary background model, following a complete material screening program, points to levels of the order of 1-10 counts keV-1 kg-1 d-1 in the region of interest, making TREX-DM competitive. The status of the commissioning, description of the background model and the corresponding WIMP sensitivity will be presented here

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

First results of the CAST-RADES haloscope search for axions at 34.67 µeV

We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67 µeV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of ga¿ ¿ 4 × 10-13 GeV-1 over a mass range of 34.6738 µeV < ma< 34.6771 µeV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25 µeV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavities. © 2021, The Author(s)

Search for Dark Matter Axions with CAST-CAPP

The CAST-CAPP axion haloscope, operating at CERN inside the CAST dipole magnet, has searched for axions in the 19.74 $\mu$eV to 22.47 $\mu$eV mass range. The detection concept follows the Sikivie haloscope principle, where Dark Matter axions convert into photons within a resonator immersed in a magnetic field. The CAST-CAPP resonator is an array of four individual rectangular cavities inserted in a strong dipole magnet, phase-matched to maximize the detection sensitivity. Here we report on the data acquired for 4124 h from 2019 to 2021. Each cavity is equipped with a fast frequency tuning mechanism of 10 MHz/min between 4.774 GHz and 5.434 GHz. In the present work, we exclude axion-photon couplings for virialized galactic axions down to $g_{a{\gamma}{\gamma}} = 8 \times {10^{-14}}$ $GeV^{-1}$ at the 90% confidence level. The here implemented phase-matching technique also allows for future large-scale upgrades.Comment: 24 pages, 5 figures, Published version available with Open Access at https://www.nature.com/articles/s41467-022-33913-

Physics potential of the International Axion Observatory (IAXO)

We review the physics potential of a next generation search for solar axions:the International Axion Observatory (IAXO). Endowed with a sensitivity todiscover axion-like particles (ALPs) with a coupling to photons as small as$g_{a\gamma}\sim 10^{-12}$ GeV$^{-1}$, or to electrons $g_{ae}\sim$10$^{-13}$,IAXO has the potential to find the QCD axion in the 1 meV$\sim$1 eV mass rangewhere it solves the strong CP problem, can account for the cold dark matter ofthe Universe and be responsible for the anomalous cooling observed in a numberof stellar systems. At the same time, IAXO will have enough sensitivity todetect lower mass axions invoked to explain: 1) the origin of the anomalous"transparency" of the Universe to gamma-rays, 2) the observed soft X-ray excessfrom galaxy clusters or 3) some inflationary models. In addition, we reviewstring theory axions with parameters accessible by IAXO and discuss theirpotential role in cosmology as Dark Matter and Dark Radiation as well as theirconnections to the above mentioned conundrums

The forward physics facility at the high-luminosity LHC

High energy collisions at the High-Luminosity Large Hadron Collider (LHC) produce a large number of particles along the beam collision axis, outside of the acceptance of existing LHC experiments. The proposed Forward Physics Facility (FPF), to be located several hundred meters from the ATLAS interaction point and shielded by concrete and rock, will host a suite of experiments to probe standard model (SM) processes and search for physics beyond the standard model (BSM). In this report, we review the status of the civil engineering plans and the experiments to explore the diverse physics signals that can be uniquely probed in the forward region. FPF experiments will be sensitive to a broad range of BSM physics through searches for new particle scattering or decay signatures and deviations from SM expectations in high statistics analyses with TeV neutrinos in this low-background environment. High statistics neutrino detection will also provide valuable data for fundamental topics in perturbative and non-perturbative QCD and in weak interactions. Experiments at the FPF will enable synergies between forward particle production at the LHC and astroparticle physics to be exploited. We report here on these physics topics, on infrastructure, detector, and simulation studies, and on future directions to realize the FPF's physics potential

Looking for Low-Mass WIMPs with TREX-DM

TREX-DM is a low-mass WIMP detector: a gas time projection chamber (TPC) equipped with novel micromesh gas structures (Micromegas) readout planes. In the fiducial volume of $\sim$20 litres and a pressure of 10$\;$bar, there will be approx. 0.160$\;$kg of Ne, or alternatively 0.300$\;$kg of Ar. The energy threshold foreseen is well below 0.4~keVee and the expected background level is better than 10 counts keV$^{-1}$kg$^{-1}$d$^{-1}$, and could give competitive results in the search for low-mass WIMPs. The experiment has recently been approved by the Laboratorio Subterráneo de Canfranc and is expected to be commissioned by the end of the current year. We report on the status of the project