Direct Neutrino Mass Experiments

With a mass at least six orders of magnitudes smaller than the mass of an electron -- but non-zero -- neutrinos are a clear misfit in the Standard Model of Particle Physics. On the one hand, its tiny mass makes the neutrino one of the most interesting particles, one that might hold the key to physics beyond the Standard Model. On the other hand this minute mass leads to great challenges in its experimental determination. Three approaches are currently pursued: An indirect neutrino mass determination via cosmological observables, the search for neutrinoless double $\beta$-decay, and a direct measurement based on the kinematics of single $\beta$-decay. In this paper the latter will be discussed in detail and the status and scientific reach of the current and near-future experiments will be presented.Comment: Talk presented at NuPhys2015 (London, 16-18 December 2015). 9 pages, LaTeX, 9 png figure

Status of the KATRIN Experiment and Prospects to Search for keV-mass Sterile Neutrinos in Tritium β-decay

AbstractIn this contribution the current status and future perspectives of the Karlsruhe Tritium Neutrino (KATRIN) Experiment are presented. The prime goal of this single β-decay experiment is to probe the absolute neutrino mass scale with a sensitivity of 200 meV (90% CL). We discuss first results of the recent main spectrometer commissioning measurements, successfully verifying the spectrometer's basic vacuum, transmission and background properties. We also discuss the prospects of making use of the KATRIN tritium source, to search for sterile neutrinos in the multi-keV mass range constituting a classical candidate for Warm Dark Matter. Due to the very high source luminosity, a statistical sensitivity down to active-sterile mixing angles of sin2 θ < 1 . 10-7 (90% CL) could be reached

Tan(beta)-enhanced supersymmetric corrections to the anomalous magnetic moment of the muon

We report on a two-loop supersymmetric contribution to the magnetic moment (g-2)_mu of the muon which is enhanced by two powers of tan(beta). This contribution arises from a shift in the relation between the muon mass and Yukawa coupling and can increase the supersymmetric contribution to (g-2)_mu sizably. As a result, if the currently observed 3 sigma deviation between the experimental and SM theory value of (g-2)_mu is analyzed within the Minimal Supersymmetric Standard Model (MSSM), the derived constraints on the parameter space are modified significantly: If (g-2)_mu is used to determine tan(beta) as a function of the other MSSM parameters, our corrections decrease tan(beta) by roughly 10% for tan(beta)=50.Comment: 4 pages, 1 figur

Study of Background Processes in the Electrostatic Spectrometers of the KATRIN Experiment

The Karlsruhe Tritium Neutrino Experiment KATRIN is designed to determine the neutrino mass with a sensitivity of 200 meV (90% C.L.). The focus of this work lies on the investigation of the main background sources at KATRIN: Muon induced background, background due to penning traps, and background arising from stored electrons. A novel method to eliminate the background arising from stored electrons, based on Electron Cyclotron Resonance, was experimentally tested in this work

Probing the Neutrino-Mass Scale with the KATRIN Experiment

The absolute mass scale of neutrinos is an intriguing open question in contemporary physics. The as-yet-unknown mass of the lightest and, at the same time, most abundant massive elementary particle species bears fundamental relevance to theoretical particle physics, astrophysics, and cosmology. The most model-independent experimental approach consists of precision measurements of the kinematics of weak decays, notably tritium β decay. With the KATRIN experiment, this direct neutrino-mass measurement has entered the sub-eV domain, recently pushing the upper limit on the electron-based neutrino mass down to 0.8 eV (90% CL) on the basis of first-year data out of ongoing, multiyear operations. Here, we review the experimental apparatus of KATRIN, the progress of data taking, and initial results. While KATRIN is heading toward the target sensitivity of 0.2 eV, other scientific goals are pursued. We discuss the search for light sterile neutrinos and an outlook on future keV-scale sterile-neutrino searches as well as further physics opportunities beyond the Standard Model

Nanoencapsulation of hydrophobic phytochemicals using poly(dl-lactide-co-glycolide) (PLGA) for antioxidant and antimicrobial delivery applications: Guabiroba fruit (Campomanesia xanthocarpa O. Berg) study

AbstractPrevious studies have reported antioxidant and antimicrobial activity of guabiroba extract (GE), which is associated to its polyphenolic and carotenoid contents. Encapsulation using polymeric materials could improve GE application, bioavailability, and stability in foods and pharmaceuticals. Poly (dl-lactide-co-glycolide) (PLGA) nanoparticles with entrapped GE were synthesized using the emulsion-evaporation method with different lactide to glycolide (50:50 and 65:35) ratios to determine the dependency of polymer composition on nanoparticles antioxidant and antimicrobial activities. Controlled release experiments showed an initial burst followed by a slower release rate of carotenoids inside PLGA matrix. Both nanoparticles showed Listeria innocua growth inhibition within the concentration range tested (<1200 μg/mL), that was not observed by the free extract. Lower GE concentrations were required to reduce reactive oxygen species once it was nanoencapsulated; however, equivalent or higher concentrations for free radical scavenging were required. GE-loaded PLGA 50:50 presented the best results for antimicrobial and antioxidant delivery applications. These nanoparticles could be used with other extracts containing carotenoids and other functional lipids as delivery systems for enhanced biological activity

Tritium beta decay with additional emission of new light bosons

We consider tritium beta decay with additional emission of light pseudoscalar or vector bosons coupling to electrons or neutrinos. The electron energy spectrum for all cases is evaluated and shown to be well estimated by approximated analytical expressions. We give the statistical sensitivity of Katrin to the mass and coupling of the new bosons, both in the standard setup of the experiment as well as for future modifications in which the full energy spectrum of tritium decay is accessible

Characterization of a Silicon Drift Detector for High-Resolution Electron Spectroscopy

Silicon Drift Detectors, widely employed in high-resolution and high-rate X-ray applications, are considered here with interest also for electron detection. The accurate measurement of the tritium beta decay is the core of the TRISTAN (TRitium Investigation on STerile to Active Neutrino mixing) project. This work presents the characterization of a single-pixel SDD detector with a mono-energetic electron beam obtained from a Scanning Electron Microscope. The suitability of the SDD to detect electrons, in the energy range spanning from few keV to tens of keV, is demonstrated. Experimental measurements reveal a strong effect of the detector's entrance window structure on the observed energy response. A detailed detector model is therefore necessary to reconstruct the spectrum of an unknown beta-decay source