Exotic Dark Matter Search with the Majorana Demonstrator.

With excellent energy resolution and ultralow-level radiogenic backgrounds, the high-purity germanium detectors in the Majorana Demonstrator enable searches for several classes of exotic dark matter (DM) models. In this work, we report new experimental limits on keV-scale sterile neutrino DM via the transition magnetic moment from conversion to active neutrinos ν_{s}→ν_{a}. We report new limits on fermionic dark matter absorption (χ+A→ν+A) and sub-GeV DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), and new exclusion limits for bosonic dark matter (axionlike particles and dark photons). These searches utilize the (1-100)-keV low-energy region of a 37.5-kg y exposure collected by the Demonstrator between May 2016 and November 2019 using a set of ^{76}Ge-enriched detectors whose surface exposure time was carefully controlled, resulting in extremely low levels of cosmogenic activation.

Constraints on the Decay of

^{180m}Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known ß and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower-energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter, and K-spin violation. For this study, we repurposed the Majorana Demonstrator, an experimental search for the neutrinoless double-beta decay of ^{76}Ge using an array of high-purity germanium detectors, to search for the decay of ^{180m}Ta. More than 17 kg, the largest amount of tantalum metal ever used for such a search, was installed within the ultralow-background detector array. In this Letter, we present results from the first year of Ta data taking and provide an updated limit for the ^{180m}Ta half-life on the different decay channels. With new limits up to 1.5×10^{19} yr, we improved existing limits by 1-2 orders of magnitude which are the most sensitive searches for a single ß and electron capture decay ever achieved. Over all channels, the decay can be excluded for T_{1/2}<0.29×10^{18} yr.

First Measurement of the Nuclear-Recoil Ionization Yield in Silicon at 100 eV.

We measured the nuclear-recoil ionization yield in silicon with a cryogenic phonon-sensitive gram-scale detector. Neutrons from a monoenergetic beam scatter off of the silicon nuclei at angles corresponding to energy depositions from 4 keV down to 100 eV, the lowest energy probed so far. The results show no sign of an ionization production threshold above 100 eV. These results call for further investigation of the ionization yield theory and a comprehensive determination of the detector response function at energies below the keV scale.

Erratum: Search for Spontaneous Radiation from Wave Function Collapse in the Majorana Demonstrator [Phys. Rev. Lett. 129, 080401 (2022)].

This corrects the article DOI: 10.1103/PhysRevLett.129.080401.

Co-infection by multiple vector-borne agents in wild ring-tailed coatis (Nasua nasua) from Iguaçu National Park, southern Brazil.

The present study aimed to detect molecularly the presence of co-infections by vector-borne agents (VBA) in ring-tailed coatis' (Nasua nasua) blood samples from Iguaçu National Park (INP), southern Brazil, and assess the phylogenetic positioning of the detected agents. DNA blood samples were submitted to molecular screening and characterization for Anaplasmataceae agents, Piroplasmids, Hepatozoon sp., hemotropic mycoplasmas, and Bartonella spp. In total, 42 (85.7%) coatis were positive for hemotropic Mycoplasma sp., 12 (24.5%) for Bartonella machadoae, 7 (14.3%) for Anaplasma sp. closely related to 'Candidatus Anaplasma brasiliensis', and 3 (6%) for Hepatozoon procyonis. The most prevalent co-infections observed was from bacterial VBA: while 18.3% were co-infected by hemotropic Mycoplasma sp. and Bartonella sp., 12.2% were co-infected by Anaplasma sp. and hemotropic Mycoplasma sp. Only two animals (4%) presented co-infections by three VBA (Bartonella sp., Anaplasma sp. and hemotropic Mycoplasma sp.). The coati is a wild carnivore found in INP, mainly in areas visited by tourists. These animals are frequently seen searching for food in garbage dumps or in tourists' belongings. The present study expands the host specificity range of B. machadoae, which has been isolated only from rodents until the present moment. Since the zoonotic potential and transmission routes of the detected VBA are not yet known, surveillance in this area is much needed.

Final Result of the Majorana Demonstrator's Search for Neutrinoless Double-ß Decay in

The Majorana Demonstrator searched for neutrinoless double-ß decay (0νßß) of ^{76}Ge using modular arrays of high-purity Ge detectors operated in vacuum cryostats in a low-background shield. The arrays operated with up to 40.4 kg of detectors (27.2 kg enriched to ∼88% in ^{76}Ge). From these measurements, the Demonstrator has accumulated 64.5 kg yr of enriched active exposure. With a world-leading energy resolution of 2.52 keV FWHM at the 2039 keV Q_{ßß} (0.12%), we set a half-life limit of 0νßß in ^{76}Ge at T_{1/2}>8.3×10^{25} yr (90% C.L.). This provides a range of upper limits on m_{ßß} of (113-269) meV (90% C.L.), depending on the choice of nuclear matrix elements.

Search for Spontaneous Radiation from Wave Function Collapse in the Majorana Demonstrator.

The Majorana Demonstrator neutrinoless double-beta decay experiment comprises a 44 kg (30 kg enriched in ^{76}Ge) array of p-type, point-contact germanium detectors. With its unprecedented energy resolution and ultralow backgrounds, Majorana also searches for rare event signatures from beyond standard model physics in the low energy region below 100 keV. In this Letter, we test the continuous spontaneous localization (CSL) model, one of the mathematically well-motivated wave function collapse models aimed at solving the long-standing unresolved quantum mechanical measurement problem. While the CSL predicts the existence of a detectable radiation signature in the x-ray domain, we find no evidence of such radiation in the 19-100 keV range in a 37.5 kg-y enriched germanium exposure collected between December 31, 2015, and November 27, 2019, with the Demonstrator. We explored both the non-mass-proportional (n-m-p) and the mass-proportional (m-p) versions of the CSL with two different assumptions: that only the quasifree electrons can emit the x-ray radiation and that the nucleus can coherently emit an amplified radiation. In all cases, we set the most stringent upper limit to date for the white CSL model on the collapse rate, λ, providing a factor of 40-100 improvement in sensitivity over comparable searches. Our limit is the most stringent for large parts of the allowed parameter space. If the result is interpreted in terms of the Diòsi-Penrose gravitational wave function collapse model, the lower bound with a 95% confidence level is almost an order of magnitude improvement over the previous best limit.

Search for Solar Axions via Axion-Photon Coupling with the Majorana Demonstrator.

Axions were originally proposed to explain the strong-CP problem in QCD. Through axion-photon coupling, the Sun could be a major source of axions, which could be measured in solid state detection experiments with enhancements due to coherent Primakoff-Bragg scattering. The Majorana Demonstrator experiment has searched for solar axions with a set of ^{76}Ge-enriched high purity germanium detectors using a 33 kg-yr exposure collected between January, 2017 and November, 2019. A temporal-energy analysis gives a new limit on the axion-photon coupling as g_{aγ}<1.45×10^{-9} GeV^{-1} (95% confidence level) for axions with mass up to 100 eV/c^{2}. This improves laboratory-based limits between about 1 eV/c^{2} and 100 eV/c^{2}.

α -event characterization and rejection in point-contact HPGe detectors.

P-type point contact (PPC) HPGe detectors are a leading technology for rare event searches due to their excellent energy resolution, low thresholds, and multi-site event rejection capabilities. We have characterized a PPC detector's response to α particles incident on the sensitive passivated and p + surfaces, a previously poorly-understood source of background. The detector studied is identical to those in the Majorana Demonstrator experiment, a search for neutrinoless double-beta decay ( 0 ν ß ß ) in 76 Ge. α decays on most of the passivated surface exhibit significant energy loss due to charge trapping, with waveforms exhibiting a delayed charge recovery (DCR) signature caused by the slow collection of a fraction of the trapped charge. The DCR is found to be complementary to existing methods of α identification, reliably identifying α background events on the passivated surface of the detector. We demonstrate effective rejection of all surface α events (to within statistical uncertainty) with a loss of only 0.2% of bulk events by combining the DCR discriminator with previously-used methods. The DCR discriminator has been used to reduce the background rate in the 0 ν ß ß region of interest window by an order of magnitude in the Majorana Demonstrator  and will be used in the upcoming LEGEND-200 experiment.

Constraints on Lightly Ionizing Particles from CDMSlite.

The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to lightly ionizing particles (LIPs) in a previously unexplored region of charge, mass, and velocity parameter space. We report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically produced LIPs with an electric charge smaller than e/(3×10^{5}), as well as the strongest limits for charge ≤e/160, with a minimum vertical intensity of 1.36×10^{-7} cm^{-2} s^{-1} sr^{-1} at charge e/160. These results apply over a wide range of LIP masses (5 MeV/c^{2} to 100 TeV/c^{2}) and cover a wide range of ßγ values (0.1-10^{6}), thus excluding nonrelativistic LIPs with ßγ as small as 0.1 for the first time.

Light Dark Matter Search with a High-Resolution Athermal Phonon Detector Operated above Ground.

We present limits on spin-independent dark matter-nucleon interactions using a 10.6 g Si athermal phonon detector with a baseline energy resolution of σ_{E}=3.86±0.04(stat)_{-0.00}^{+0.19}(syst) eV. This exclusion analysis sets the most stringent dark matter-nucleon scattering cross-section limits achieved by a cryogenic detector for dark matter particle masses from 93 to 140 MeV/c^{2}, with a raw exposure of 9.9 g d acquired at an above-ground facility. This work illustrates the scientific potential of detectors with athermal phonon sensors with eV-scale energy resolution for future dark matter searches.

Caracterização da fauna helmintológica de tamanduá-bandeira (Myrmecophaga tridactyla) e tamanduá-mirim (Tamandua tetradactyla) atropelados nas rodovias BR-050 e BR-455 (Minas Gerais, Brasil) / [Helmintological characterization of giant anteater (Myrmecophaga tridactyla) and lesser anteater (Tamandua tetradactyla) roadkilled on BR-050 and BR-455 highways (Minas Gerais, Brazil)]

O tamanduá-bandeira (Myrmecophaga tridactyla) e o tamanduá-mirim (Tamandua tetradactyla) são mamíferos xenartros amplamente distribuídos no território nacional. Apesar disso, suas populações estão em constante ameaça, principalmente o primeiro, categorizado como vulnerável de acordo com classificação da União Internacional para Conservação da Natureza. Diante disso e da escassez de estudos com endoparasitas nesses animais, objetivou-se descrever a helmintofauna dessas duas espécies de tamanduá, utilizando espécimes atropelados nas rodovias BR-050 e BR-455, região do Triângulo Mineiro, Minas Gerais, Brasil. Os animais foram submetidos à necropsia, tendo seus órgãos e conteúdo intestinal e estomacal examinados para recuperação de helmintos. Os parasitos coletados foram identificados com base em suas características morfológicas e morfométricas. As espécies/os gêneros caracterizados para M. tridactyla e T. tetradactyla, suas respectivas prevalências, bem como órgãos de origem, foram: Gaphidiops dissimilis (33,33% e 0%) no estômago; Gigantorhynchus echinodiscus (25% e 66,66%) no intestino delgado; Physaloptera magnipapilla (50% e 66,6%) no estômago; e Mathevotaenia spp. (25% e 66,66%) no intestino delgado. Physaloptera magnipapilla foi a espécie com os maiores índices de infecção, e novo registro de localização foi registrado para o nematódeo Graphidiops dissimilis. Detectou-se uma provável sobreposição da área de vida dos tamanduás estudados, bem como uma helmintofauna característica da região.(AU)

Myrmecophaga tridactyla, giant anteater and Tamandua tetradactyla, collared anteater are nationally widespread mammals. Despite that, their populations are in danger, especially the first one, categorized as vulnerable according to the International Union for Conservation of Nature. This study reports the occurrence of helminths in these two anteater species using road killed specimens from BR-050 and BR-455 highways, Triângulo Mineiro region, Minas Gerais state, Brazil. The species were necropsied, and their gastrointestinal organs and contents were opened and examined for parasite recovery. The identification was based on morphological and morphometric features. The species/ genera found for M. tridactyla and T. tetradactyla, their prevalence, as well the organs, were: Gaphidiops dissimilis (33.33% and 0%) in stomach; Gigantorhynchus echinodiscus (25% and 66.66%) in small intestine; Physaloptera magnipapilla (50% and 66.6%) in stomach and Mathevotaenia spp. (25% and 66.66%) in small intestine. Physaloptera magnipapilla was the most common species and a new location was reported for Graphidiops dissimilis. There is a probable overlap in the home range of these animals and a local helminth diversity was described on the study site.(AU)

Results on Low-Mass Weakly Interacting Massive Particles from an 11 kg d Target Exposure of DAMIC at SNOLAB.

We present constraints on the existence of weakly interacting massive particles (WIMPs) from an 11 kg d target exposure of the DAMIC experiment at the SNOLAB underground laboratory. The observed energy spectrum and spatial distribution of ionization events with electron-equivalent energies >200 eV_{ee} in the DAMIC CCDs are consistent with backgrounds from natural radioactivity. An excess of ionization events is observed above the analysis threshold of 50 eV_{ee}. While the origin of this low-energy excess requires further investigation, our data exclude spin-independent WIMP-nucleon scattering cross sections σ_{χ-n} as low as 3×10^{-41} cm^{2} for WIMPs with masses m_{χ} from 7 to 10 GeV c^{-2}. These results are the strongest constraints from a silicon target on the existence of WIMPs with m_{χ}<9 GeV c^{-2} and are directly relevant to any dark matter interpretation of the excess of nuclear-recoil events observed by the CDMS silicon experiment in 2013.

Parasitological assessment of wild ring-tailed coatis (Nasua nasua) from the Brazilian Atlantic rainforest.

Image 1.

The South American lungfish Lepidosiren paradoxa as a new host for Trichodina quelenii / O lungfish sul-americano Lepidosiren paradoxa como novo hospedeiro para Trichodina quelenii

Abstract Recently, the South American lungfish Lepidosiren paradoxa is being found inside aquaculture ponds, and even though there are a few studies on their parasite fauna, there is still much to be reported. Thus, the objective of this study is to report parasitism by trichodinids in L. paradoxa, as these ciliate protozoa are related to injuries and mortality in fish farming. The lungfish were collected from experimental tanks, had their tegument scraped and the resultant mucus was analyzed under an optical microscope for morphological and morphometrical analyses in Giemsa and silver nitrate stained slides. The species found was identified as Trichodina quelleni. This is the first report of this parasite in L. paradoxa, and the second report in cultivated fish in Brazil.

Resumo Recentemente, o peixe pulmonado sul-americano Lepidosiren paradoxa tem sido encontrado em tanques de cultivo da aquicultura e, embora existam alguns estudos sobre a fauna de parasitas neste hospedeiro, ainda há muito a ser relatado. Assim, o objetivo deste estudo é relatar o parasitismo por tricodinídeos em L. paradoxa, pois esses protozoários ciliados estão relacionados a lesões e mortalidade na piscicultura. Os peixes foram coletados de tanques experimentais, tiveram seu tegumento raspado e o muco resultante foi analisado sob um microscópio óptico para análises morfológicas e morfométricas em lâminas impregnadas com Nitrato de Prata e com Giemsa. Os espécimes encontrados foram identificados como Trichodina quelleni. Este é o primeiro registro deste parasita em L. paradoxa, e a segunda ocorrência de Trichodina quelenii em peixes cultivados no Brasil.

Erratum: First Dark Matter Constraints from a SuperCDMS Single-Charge Sensitive Detector [Phys. Rev. Lett. 121, 051301 (2018)].

This corrects the article DOI: 10.1103/PhysRevLett.121.051301.

The South American lungfish Lepidosiren paradoxa as a new host for Trichodina quelenii.

Recently, the South American lungfish Lepidosiren paradoxa is being found inside aquaculture ponds, and even though there are a few studies on their parasite fauna, there is still much to be reported. Thus, the objective of this study is to report parasitism by trichodinids in L. paradoxa, as these ciliate protozoa are related to injuries and mortality in fish farming. The lungfish were collected from experimental tanks, had their tegument scraped and the resultant mucus was analyzed under an optical microscope for morphological and morphometrical analyses in Giemsa and silver nitrate stained slides. The species found was identified as Trichodina quelleni. This is the first report of this parasite in L. paradoxa, and the second report in cultivated fish in Brazil.

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 g CDMS high-voltage device). These electron-recoil limits significantly improve experimental constraints on dark matter particles with masses as low as 1 MeV/c^{2}. We demonstrate a sensitivity to dark photons competitive with other leading approaches but using substantially less exposure (0.49 g d). These results demonstrate the scientific potential of phonon-mediated semiconductor detectors that are sensitive to single electronic excitations.

Osteoporosis treatment and 10 years' oestrogen receptor+ breast cancer outcome in postmenopausal women treated with aromatase inhibitors.

BACKGROUND: Risk factors for breast cancer relapse are well-known, such as large tumour size or lymph node involvement. The aim of our study was to analyse the influence of bone mineral density, fractures and bisphosphonate or vitamin D prescription on 10 years' breast cancer outcome. PATIENTS AND METHODS: This is a longitudinal and prospective cohort of 450 postmenopausal women with local oestrogen receptor (ER)+ breast cancer. For every patient, we analysed tumour characteristics, bone status at the beginning of aromatase inhibitor treatment and 10 years' cancer outcome with Cox model. RESULTS: Mean follow-up was 10.3 ± 3.0 years. Seventy nine women died, and 75 had a relapse; 30.7% had a history of fracture, 16.9% had a T-score ≤ -2.5 and 11.3% had vitamin D deficiency. Bisphosphonates were prescribed to 35.3% women for osteoporosis for a mean duration of 5 ± 1.7 years. Tumour size (hazard ratio [HR] = 1.32, P ≤ 0.01) and the number of lymph nodes involved (HR = 1.07, P = 0.03) were significantly associated with relapse. Bisphosphonate treatment was significantly associated with a decreased risk of relapse (HR = 0.51, P = 0.03). Age at cancer diagnosis (HR = 1.07, P ≤ 0.01) and vitamin D deficiency (HR = 1.85, P = 0.04) were significantly associated with an increased risk of death, whereas bisphosphonate treatment was associated with a decreased risk of death (HR = 0.46, P = 0.01). CONCLUSION: Osteoporosis treatment, including vitamin D and bisphosphonates, is associated with a 50% reduction of relapse and death in women treated with aromatase inhibitors for ER+ breast cancer.

First Limit on the Direct Detection of Lightly Ionizing Particles for Electric Charge as Low as e/1000 with the Majorana Demonstrator.

The Majorana Demonstrator is an ultralow-background experiment searching for neutrinoless double-beta decay in ^{76}Ge. The heavily shielded array of germanium detectors, placed nearly a mile underground at the Sanford Underground Research Facility in Lead, South Dakota, also allows searches for new exotic physics. Free, relativistic, lightly ionizing particles with an electrical charge less than e are forbidden by the standard model but predicted by some of its extensions. If such particles exist, they might be detected in the Majorana Demonstrator by searching for multiple-detector events with individual-detector energy depositions down to 1 keV. This search is background-free, and no candidate events have been found in 285 days of data taking. New direct-detection limits are set for the flux of lightly ionizing particles for charges as low as e/1000.