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

^{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 β 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 β and electron capture decay ever achieved. Over all channels, the decay can be excluded for T_{1/2}<0.29×10^{18}  yr.

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.

Final Result of the Majorana Demonstrator's Search for Neutrinoless Double-β Decay in ^{76}Ge

The Majorana Demonstrator searched for neutrinoless double-β decay (0νββ) 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_{ββ} (0.12%), we set a half-life limit of 0νββ in ^{76}Ge at T_{1/2}>8.3×10^{25}  yr (90% C.L.). This provides a range of upper limits on m_{ββ} of (113-269) meV (90% C.L.), depending on the choice of nuclear matrix elements.

Does land-based exercise-therapy improve physical activity in people with knee osteoarthritis? A systematic review with meta-analyses

PRIMARY OBJECTIVE

Investigate the effects of land-based exercise-therapy on physical activity in people with knee osteoarthritis (KOA).

DESIGN

Systematic review and meta-analysis of randomised or quasi-randomised trials investigating land-based exercise-therapy on physical activity, fitness, and general health in people with KOA. We updated a 2013 Cochrane review search on exercise-therapy for KOA in April 2021 and applied the Cochrane Risk-of-Bias Tool 1.0 to included articles. Standardised mean differences (SMDs) and 95% confidence intervals (CI) were calculated. GRADE was used to assess certainty of the evidence.

RESULTS

Twenty-eight randomised controlled trials (2,789 participants) evaluating the effects of resistance-training (n = 10), walking (n = 6) and mixed-exercise programs (n = 7) were identified. Low to moderate certainty evidence indicated small increases in physical activity for exercise-therapy compared to non-exercise interventions in the short-term (SMD, 95% CI = 0.29, 0.09 to 0.50), but not the medium- (0.03, -0.11 to 0.18) or long-term (-0.06, -0.34 to 0.22). Low certainty evidence indicated large increases in physical activity for walking programs (0.53, 0.11 to 0.95) and mixed-exercise programs (0.67, 0.37 to 0.97) compared to non-exercise interventions in the short-term. Low certainty evidence indicated moderate and small increases in physical activity for resistance-training combined with education focused on pain coping skills and self-efficacy compared to education alone at medium-term follow-up (0.45, 0.19 to 0.71).

CONCLUSION

Walking and mixed-exercise, but not resistance-training, may improve physical activity in people with KOA in the short-term. Combining resistance-training with education may increase physical activity in the medium-, but not the long-term, highlighting the potential importance of developing more effective longer-term interventions for people with KOA. Future studies evaluating land-based exercise-therapy are encouraged to include physical activity outcomes and longer-term follow-up to increase the certainty of evidence.

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 β β ) 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 β β region of interest window by an order of magnitude in the Majorana Demonstrator  and will be used in the upcoming LEGEND-200 experiment.

Immediate outcomes following the GLA:D® program in Denmark, Canada and Australia. A longitudinal analysis including 28,370 patients with symptomatic knee or hip osteoarthritis

OBJECTIVE

To report outcomes across three countries for patients with symptomatic knee or hip OA attending the evidence-based education and exercise therapy program Good Life with osteoArthritis from Denmark (GLA:D®).

DESIGN

GLA:D® is a structured treatment program including 2-3 patient education sessions and 12 supervised exercise sessions delivered over 8 weeks by certified health care practitioners. The program was introduced in Denmark in 2013, in Canada 2015 and in Australia 2016. Absolute mean change in pain intensity, number of chair stands in 30 s, 40 m walk test time and Knee injury and Osteoarthritis Outcome Score (KOOS)/Hip dysfunction and Osteoarthritis Outcome Score (HOOS) QOL subscale scores from baseline to immediately after treatment were reported as means and 95 % CIs and proportion of responders for each country.

RESULTS

Patients from the three countries improved 26-33% in mean pain intensity, 8-12% in walking speed, 18-30% in chair stand ability and 12-26% in joint-related quality of life from baseline to immediately after treatment, with no clinically relevant differences between patients with hip and knee OA. These improvements correspond with moderate to large within-group effect sizes and 43-47 % of the patients experienced clinically relevant pain reductions.

CONCLUSION

About half or more of patients across the three countries were categorized as responders for pain and objective function following the implementation of GLA:D®. These findings indicate positive patient outcomes associated with GLA:D® participation across varying health care systems from implementation of guideline-based patient education and exercise therapy for knee and hip OA.

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.

Search for Neutrinoless Double-β Decay in ^{76}Ge with the Majorana Demonstrator

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in ^{76}Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in ^{76}Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. Here we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q_{ββ} and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9×10^{25}  yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0_{-2.5}^{+3.1}  counts/(FWHM t yr).

Greater peak rearfoot eversion predicts foot orthoses efficacy in individuals with patellofemoral pain syndrome

OBJECTIVE

There is growing evidence for the provision of foot orthoses when treating individuals with patellofemoral pain syndrome (PFPS), and prescription is frequently based on the assessment of foot posture/function. However, evaluation of the link between abnormal foot posture/function and foot orthoses outcomes has previously been limited to static alignment measures and has produced inconsistent findings. In this study, the ability of baseline foot kinematics associated with pronation to predict marked improvement 12 weeks following foot orthoses prescription in individuals with PFPS was evaluated.

METHODS

26 individuals with PFPS were issued with prefabricated foot orthoses, and patient-reported level of improvement was documented at 12 weeks. Potential predictors of marked improvement at 12 weeks were measured during walking at baseline and included forefoot dorsiflexion and abduction, and rearfoot eversion.

RESULTS

Of the 25 participants who completed the study, seven (28%) reported marked improvement with the foot orthoses after 12 weeks. Discriminant function analysis revealed a greater peak rearfoot eversion to be the only significant independent predictor of marked improvement.

CONCLUSION

These findings provide preliminary evidence that greater peak rearfoot eversion is predictive of marked improvement 12 weeks following prefabricated foot orthoses prescription in individuals with PFPS. Therefore, foot orthoses may be most effective in the subgroup of people with PFPS and increased dynamic foot pronation.

Measurement of the sign of the spectroscopic quadrupole moment for the 2(1)+ state in 70Se: no evidence for oblate shape

Using a method whereby molecular and atomic ions are independently selected, an isobarically pure beam of 70Se ions was postaccelerated to an energy of 206 MeV using REX-ISOLDE. Coulomb-excitation yields for states in the beam and target nuclei were deduced by recording deexcitation gamma rays in the highly segmented MINIBALL gamma-ray spectrometer in coincidence with scattered particles in a silicon detector. At these energies, the Coulomb-excitation yield for the first 2+ state is expected to be strongly sensitive to the sign of the spectroscopic quadrupole moment through the nuclear reorientation effect. Experimental evidence is presented here for a prolate shape for the first 2+ state in 70Se, reopening the question over whether there are, as reported earlier, deformed oblate shapes near to the ground state in the light selenium isotopes.

Stabilization of nuclear isovector valence-shell excitations

Excited states in 138Ce have been studied via the 12C(138Ce, 138Ce*) Coulomb excitation reaction at 480 MeV. Relative cross sections have been determined from the gamma-ray yields observed with Gammasphere. The E2 and M1 strength distributions between the lowest six 2+ states up to 2.7 MeV enables us to identify the 2(4)+ state in 138Ce as the dominant fragment of the one-phonon 2(1,ms)+ mixed-symmetry state. Mixing between this level and a nearby isoscalar state is observed and is more than 4 times larger than in the neighboring isotone 136Ba. This is direct evidence that the stability of mixed-symmetry states strongly depends on the underlying subshell structure.

B(E2) values in 150Nd and the critical point symmetry X(5)

Lifetimes of states in 150Nd were measured using the recoil distance method following Coulomb excitation of 150Nd by a 132 MeV 32S beam. The experiment was performed at the Yale Tandem accelerator, employing the SPEEDY gamma-ray detector array and the New Yale Plunger Device. Reduced transition probabilities in 150Nd are compared to the predictions of the critical point symmetry X(5) of the phase/shape transition that occurs for the N = 90 rare earth isotones. Very good agreement was observed between the parameter-free (apart from scale) X(5) predictions and the low-spin level scheme of 150Nd, revealing this as the best case thus far for the realization of the X(5) symmetry.

Coulomb excitation of radioactive 132,134,136Te beams and the low B(E2) of 136Te

The B(E2;0(+)-->2+) values for the first 2+ excited states of neutron-rich 132,134,136Te have been measured using Coulomb excitation of radioactive ion beams. The B(E2) values obtained for 132,134Te are in excellent agreement with expectations based on the systematics of heavy stable Te isotopes, while that for 136Te is unexpectedly small. These results are discussed in terms of proton-neutron configuration mixing and shell-model calculations using realistic effective interactions.

Prenatal diagnosis in factor XIII-A deficiency

Congenital factor XIII deficiency is a severe bleeding disorder that is inherited as an autosomal recessive trait. The condition is commonly due to absence of the factor XIII-A subunit protein in the plasma. The case of a baby is reported who showed typical clinical features of factor XIII-A deficiency, including recurrent bleeding from the umbilical stump and a life threatening haemorrhage after circumcision. Family studies were performed and molecular analysis, using a Short Tandem Repeat (STR) marker closely linked to the A subunit gene, allowed antenatal exclusion diagnosis to be undertaken in a subsequent pregnancy. The case highlights the importance of seeking a family history of bleeding disorders before surgery in the neonatal period, particularly if the parents are consanguineous.

Agranulocytosis during malaria prophylaxis with Maloprim (pyrimethamine and dapsone)

A case of agranulocytosis during malaria prophylaxis with Maloprim (pyrimethamine and dapsone) is described. At the recommended dose of one tablet weekly this is apparently a rare occurrence but highlights one of the hazards in a changing climate of malarial prophylaxis in which the use of Maloprim is increasing.

Intestinal malabsorption in Strongyloides stercoralis infestation

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