The MAJORANA experiment: An ultra-low background search for neutrinoless double-beta decay

The observation of neutrinoless double-beta decay would resolve the Majorana nature of the neutrino and could provide information on the absolute scale of the neutrino mass. The initial phase of the MAJORANA experiment, known as the DEMONSTRATOR, will house 40 kg of Ge in an ultra-low background shielded environment at the 4850' level of the Sanford Underground Laboratory in Lead, SD. The objective of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a narrow region of interest around the 76Ge neutrinoless double-beta decay peak

The MAJORANA DEMONSTRATOR for 0νββ: Current Status and Future Plans

The MAJORANA DEMONSTRATOR will search for neutrinoless-double-beta decay (0νββ) in 76Ge, while establishing the feasibility of a future tonne-scale germanium-based 0νββ experiment, and performing searches for new physics beyond the Standard Model. The experiment, currently under construction at the Sanford Underground Research Facility in Lead, SD, will consist of a pair of modular high-purity germanium detector arrays housed inside of a compact copper, lead, and polyethylene shield. Through a combination of strict materials qualifications and assay, low-background design, and powerful background rejection techniques, the Demonstrator aims to achieve a background rate in the 0νββ region of interest (ROI) of no more than 3 counts in the 0νββ-decay ROI per tonne of target isotope per year (cnts/(ROI-t-y)). The current status of the Demonstrator is discussed, as are plans for its completion

A Dark Matter Search with MALBEK

The Majorana Demonstrator is an array of natural and enriched high purity germanium detectors that will search for the neutrinoless double-beta decay of 76Ge and perform a search for weakly interacting massive particles (WIMPs) with masses below 10 GeV. As part of the Majorana research and development efforts, we have deployed a modified, low-background broad energy germanium detector at the Kimballton Underground Research Facility. With its sub-keV energy threshold, this detector is sensitive to potential non-Standard Model physics, including interactions with WIMPs. We discuss the backgrounds present in the WIMP region of interest and explore the impact of slow surface event contamination when searching for a WIMP signal

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

The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in Ge76. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in Ge76) 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 Qββ 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 1.9×1025 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)

Efficacy of anatomical prostheses in primary glenohumeral osteoarthritis

More than 32.8% of the over-60s suffer from shoulder osteoarthritis. For advanced osteoarthritis, arthroplasty is the treatment of choice. Current systems have moved on from the first shoulder prosthesis implanted by Neer in 1974, thanks to the use of adaptable modular systems. The aim of this study was to investigate the effectiveness of anatomical shoulder replacements in 30 cases of primary glenohumeral osteoarthritis through clinical and radiographic follow-up for a mean of 5 years. All implants were total cemented prostheses. Preoperative investigations included a clinical examination, conventional X-rays and CT. The Constant-Murley scale was used to evaluate the results; the mean score increased from 21.4 preoperative to 69.8 postoperative (p<0.05). In patients aged under 50, the increase in the mean postoperative Constant Score and ROM was greater than for the sample as a whole. The following complications were encountered: 2 postoperative radial nerve paralyses, resolving in 3 months, 2 cases of glenoid loosening, 1 periprosthetic fracture and 3 cases of pain and stiffness. The results led us to conclude that anatomical prostheses are effective in the treatment of severe primary glenohumeral arthropathy

Final Results From The Ktev Experiment On The Decay Kl→π0γ γ

We report on a new measurement of the branching ratio B(KL→π 0γγ) using the KTeV detector. We reconstruct 1982 events with an estimated background of 608, that results in B(KL→π0γγ)=(1. 29±0.03stat±0.05syst)×10-6. We also measure the parameter, aV, which characterizes the strength of vector meson exchange terms in this decay. We find aV=-0.31±0.05stat±0.07syst. These results utilize the full KTeV data set collected from 1997 to 2000 and supersede earlier KTeV measurements of the branching ratio and aV. © 2008 The American Physical Society.7711Barr, G.D., (1990) Phys. Lett. B, 242, p. 523. , PYLBAJ 0370-2693 10.1016/0370-2693(90)91806-MPapadimitriou, V., (1991) Phys. Rev. D, 44, p. 573. , PRVDAQ 0556-2821 10.1103/PhysRevD.44.R573Barr, G.D., (1992) Phys. Lett. B, 284, p. 440. , PYLBAJ 0370-2693 10.1016/0370-2693(92)90458-GEcker, G., Pich, A., De Rafael, E., (1987) Phys. Lett. B, 189, p. 363. , PYLBAJ 0370-2693 10.1016/0370-2693(87)91448-1D'Ambrosio, G., Portoles, J., (1997) Nucl. Phys., 492, p. 417. , NUPBBO 0550-3213 10.1016/S0550-3213(97)00116-8Gabbiani, F., Valencia, G., (2002) Phys. Rev. D, 66, p. 074006. , PRVDAQ 0556-2821 10.1103/PhysRevD.66.074006Truong, T.N., (1993) Phys. Lett. B, 313, p. 221. , PYLBAJ 0370-2693 10.1016/0370-2693(93)91216-AAlavi-Harati, A., (2004) Phys. Rev. Lett., 93, p. 021805. , PRLTAO 0031-9007 10.1103/PhysRevLett.93.021805Alavi-Harati, A., (2000) Phys. Rev. Lett., 84, p. 5279. , PRLTAO 0031-9007 10.1103/PhysRevLett.84.5279Buchalla, G., D'Ambrosio, G., Isidori, G., (2003) Nucl. Phys., 672, p. 387. , NUPBBO 0550-3213 10.1016/j.nuclphysb.2003.09.010Mescia, F., Smith, C., Trine, S., J. High Energy Phys., 2006 (8), p. 88. , JHEPFG 1029-8479 10.1088/1126-6708/2006/08/088Batley, J.R., (2003) Phys. Lett. B, 576, p. 43. , PYLBAJ 0370-2693 10.1016/j.physletb.2003.10.001Alavi-Harati, A., (1999) Phys. Rev. Lett., 83, p. 917. , PRLTAO 0031-9007 10.1103/PhysRevLett.83.917Lai, A., (2002) Phys. Lett. B, 536, p. 229. , PYLBAJ 0370-2693 10.1016/S0370-2693(02)01863-4Alavi-Harati, A., (2003) Phys. Rev. D, 67, p. 012005. , PRVDAQ 0556-2821 10.1103/PhysRevD.67.012005Alavi-Harati, A., (2003) Phys. Rev. D, 67, p. 012005. , PRVDAQ 0556-2821 10.1103/PhysRevD.67.012005Bown, C., (1996) Nucl. Instrum. Methods Phys. Res., Sect. a, 369, p. 248. , NIMAER 0168-9002 10.1016/0168-9002(95)00799-7Brun, R., Carminati, F., W5013 (unpublished)Alexopoulos, T., (2004) Phys. Rev. D, 70, p. 092006. , PRVDAQ 0556-2821 10.1103/PhysRevD.70.092006Yao, W.-M., (2006) J. Phys. G, 33, p. 1. , JPGPED 0954-3899 10.1088/0954-3899/33/1/001http://www.aip.org/pubservs/epaps.html, See EPAPS Document No. E-PRVDAQ-77-071811 for tables of data and acceptance used in extracting aV. For more information on EPAPS, se

Search for neutron dark decay: n → χ + e+e−

In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. One of the possible final states discussed includes a single χ along with an e+e− pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼ 4π acceptance using a pair of detectors that observe a volume of stored Ultracold Neutrons (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e- + ν̅e decays. The summed kinetic energy (Ee+e−) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel

Search for neutron dark decay:

In January, 2018, Fornal and Grinstein proposed that a previously unobserved neutron decay branch to a dark matter particle (χ) could account for the discrepancy in the neutron lifetime observed in two different types of experiments. One of the possible final states discussed includes a single χ along with an e+e− pair. We use data from the UCNA (Ultracold Neutron Asymmetry) experiment to set limits on this decay channel. Coincident electron-like events are detected with ∼ 4π acceptance using a pair of detectors that observe a volume of stored Ultracold Neutrons (UCNs). We use the timing information of coincidence events to select candidate dark sector particle decays by applying a timing calibration and selecting events within a physically-forbidden timing region for conventional n → p + e- + ν̅e decays. The summed kinetic energy (Ee+e−) from such events is reconstructed and used to set limits, as a function of the χ mass, on the branching fraction for this decay channel