Synthetic amorphous silica (SAS), manufactured in pyrogenic or precipitated form, is a nanomaterial with a widespread use as food additive (E 551). Oral exposure to SAS results from its use in food and dietary supplements, pharmaceuticals and toothpaste. Recent evidence suggests that oral exposure to SAS may pose health risks and highlights the need to address the toxic potential of SAS as affected by the physicochemical characteristics of the different forms of SAS. For this aim, investigating SAS toxicokinetics is of crucial importance and an analytical strategy for such an undertaking is presented. The minimization of silicon background in tissues, control of contamination (including silicon release from equipment), high-throughput sample treatment, elimination of spectral interferences affecting inductively coupled plasma mass spectrometry (ICP-MS) silicon detection, and development of analytical quality control tools are the cornerstones of this strategy. A validated method combining sample digestion with silicon determination by reaction cell ICP-MS is presented. Silica particles are converted to soluble silicon by microwave dissolution with mixtures of HNO3, H2O2 and hydrofluoric acid (HF), whereas interference-free ICP-MS detection of total silicon is achieved by ion-molecule chemistry with limits of detection (LoDs) in the range 0.2–0.5 µg Si g−1 for most tissues. Deposition of particulate SiO2 in tissues is assessed by single particle ICP-MS.
Detectors are a key feature of the contemporary scientific approach to cultural heritage (CH), both for diagnostics and conservation. INFN-CHNet is the network of the Italian National Institute of Nuclear Physics that develops and applies new instrumentation for the study of CH. This process results in both optimized traditional state-of-the-art and highly innovative detection setups for spectrometric techniques. Examples of the former are X-rays, gamma-rays, visible-light and particles spectrometers tailored for CH applications, with optimized performances, reliability, weight, transportability, cost, absorbed power, and complementarity with other techniques. Regarding the latter, examples are ARDESIA, the array of detectors at the DAΦNE-Light facility, the MAXRS detection setup at the Riken-RAL muon beamline and the imaging facilities at the LENA Laboratory. Paths for next-generation instruments have been suggested, as in the case of the X-ray Superconductive Detectors and X-ray Microcalorimeter Spectrometers, allowing astonishing improvement in energy resolution. Many issues in CH can now be addressed thanks to scientific techniques exploiting the existing detectors, while many others are still to be addressed and require the development of new approaches and detectors.
1 April 2016 in Nuclear and Particle Physics Proceedings
The GERDA (GERmanium Detector Array) is an experiment for the search of neutrinoless double beta decay (0 nu beta beta) in Ge-76, located at Laboratori Nazionali del Gran Sasso of INFN (Italy). In the first phase of the experiment, a 90% confidence level (C.L.) sensitivity of 2.4 . 10(25) yr on the 0 nu beta beta decay half-life was achieved with a 21.6 kg.yr exposure and an unprecedented background index in the region of interest of 10(-2) counts/(keV.kg.yr). No excess of signal events was found, and an experimental lower limit on the half-life of 2.1 . 10(25) yr (90% C.L.) was established. Correspondingly, the limit on the effective Majorana neutrino mass is m(ee) < 0.2-0.4 eV, depending on the considered nuclear matrix element. The previous claim for evidence of a 0 nu beta beta decay signal is strongly disfavored, and the field of research is open again
The determination of the absolute neutrino mass scale remains a fundamental open question in particle physics, with profound implications for both the standard model and cosmology. Direct kinematic measurements, independent of model-dependent assumptions, provide the most robust approach to address this challenge. Here we present the most stringent upper bound on the effective electron neutrino mass ever obtained with a calorimetric measurement of the electron capture decay of Ho 163 . The HOLMES experiment employs an array of ion-implanted transition-edge sensor (TES) microcalorimeters, achieving an average energy resolution of 6 eV FWHM with a scalable, multiplexed readout technique. With a total of 7 × 10 7 decay events recorded over two months and a Bayesian statistical analysis, we derive an upper limit of m β < 27 eV / c 2 at 90% credibility. These results validate the feasibility of Ho 163 calorimetry for next-generation neutrino mass experiments and demonstrate the potential of a scalable TES-based microcalorimetric technique to push the sensitivity of direct neutrino mass measurements beyond the current state of the art.
A new search for the decay modes of the fourfold forbidden nonunique decay of has been performed at the Gran Sasso Underground Laboratory (LNGS). In total, an exposure of 197 kg d has been accumulated. The half-life for the electron capture into the first excited state of has been measured with the highest precision to date as yr (68% C.I.) in which systematics uncertainties dominate. The search for the decay into the first excited state of resulted in a lower limit of yr (90% C.I.), which is an improvement of almost one order of magnitude compared to existing results. The sensitivity of the new measurement is now in the region of theoretical predictions.