Results 1 - 10 of 465827
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[en] We present a technique for estimating the number of future 0νββ results using several distinct nuclei to optimize the physics reach of upcoming experiments. We use presently available matrix-element calculations and simulated sets of predicted 0νββ measured rates in multiple isotopes to estimate the required precision and number of experiments to discern the underlying physics governing the mechanism of the process. Our results indicate that three (four) experimental results with total uncertainty (statistical, systematic, theoretical) of less than ∼20% (∼40%) can elucidate the underlying physics. If the theoretical (i.e. matrix-element) uncertainty contribution is below ∼18%, then three or four experimental results of ∼20% precision (statistical and systematic) are required. These uncertainty goals can be taken as guidance for the upcoming theoretical and experimental programs
[en] We discuss a general formalism needed for a unified description of the weak and electromagnetic processes in nuclei which is based on the multipole decomposition of the hadronic currents. The use of harmonic oscillator single-particle basis, which is commonly employed in many-body nuclear calculations, simplifies the relevant expressions. We present analytic formulas for the corresponding radial integrals which enter the transition matrix elements of one-body operators in various semi-leptonic nuclear processes. As an example we apply our formalism in order to simplify previous formalism giving the nuclear moments for the 0νββ decay. Our results for the radial integrals refer to the 1s-0d and 1p-0f model space. (author)
[en] Accurate mass determination employing Penning ion traps has gained increasing importance after the installation of several new on-line facilities at accelerator labs. These setups combine unique production possibilities for rare isotopes with elaborate ion-capture and manipulation techniques. Since the final commissioning of the JYFLTRAP setup at the IGISOL facility in Jyvaeskylae, the masses of more than 200 short-lived nuclides have been measured. Their knowledge applies to studies on nuclear structure, the modeling of nucleosynthesis processes, tests of the conserved vector current (CVC) hypothesis and the unitarity of the CKM matrix, and furthermore, can help to assist in ongoing searches of neutrinoless double-beta decays. This presentation focuses on recent highlights studied at JYFLTRAP
[en] In present and future experiments in the field of rare events physics a background index of 10-3 counts/(keV kg a) or better in the region of interest is envisaged. A thorough material screening is mandatory in order to achieve this goal. The results of a systematic study of radioactive trace impurities in selected materials using ultra low-level gamma-ray spectrometry in the framework of the GERDA experiment are reported.
[en] Two large crystals of carefully enriched germanium, one weighing 1 kilogram and the other 2.9 kilograms, and worth many millions of dollars, are being carefully monitored in the Italian Gran Sasso Laboratory in the continuing search for neutrinoless double beta decay
[en] A brief review of several theoretical and experimental talks related to the double-beta decay which were moderated by the author during the workshop MEDEX'99. Comments and criticisms made by some participants in the round table session are also included. (author)
[en] The nuclear matrix elements of Majorana neutrino mass mechanism of neutrinoless double-beta decay have so far been calculated using only contributions from vector axial-vector part and weak magnetism of the nuclear current, while other contributions have been neglected. In the present work we are examining the effect of weak magnetism and induced pseudoscalar coupling. We have performed calculations within the proton-neutron renormalized quasiparticle random phase approximation and we have found that these additional contributions of the nucleon current, result in a considerable reduction of the nuclear matrix elements of all nuclei which we have considered. This reduction of the nuclear matrix element makes the extracted limits of the lepton number violating parameters (
ν> and <ηN>) and less stringent yielding the best value for less than 0.51 eV for 76Ge. (author)
[en] The purpose of the present electrical signal path study is to explore the various issues related to the deployment of highly-segmented low-background Ge detectors for the MAJORANA double-beta decay experiment. A significant challenge is to simultaneously satisfy competing requirements for the mechanical design, electrical readout performance, and radiopurity specifications from the MAJORANA project. Common to all rare search experiments, there is a very stringent limit on the acceptable radioactivity level of all the electronics components involved. Some of the findings are summarized in this report.