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Search Results: 1 - 10 of 208462 matches for " L. Pandola "
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Overview of the European Underground Facilities
L. Pandola
Physics , 2011, DOI: 10.1063/1.3579554
Abstract: Deep underground laboratories are the only places where the extremely low background radiation level required for most experiments looking for rare events in physics and astroparticle physics can be achieved. Underground sites are also the most suitable location for very low background gamma-ray spectrometers, able to assay trace radioactive contaminants. Many operational infrastructures are already available worldwide for science, differing for depth, dimension and rock characteristics. Other underground sites are emerging as potential new laboratories. In this paper the European underground sites are reviewed, giving a particular emphasis on their relative strength and complementarity. A coordination and integration effort among the European Union underground infrastructures was initiated by the EU-funded ILIAS project and proved to be very effective.
Feasibility study of the observation of the neutrino accompanied double beta-decay of Ge-76 to the 0+(1) excited state of Se-76 using segmented germanium detectors
K. Kroeninger,L. Pandola,V. Tretyak
Physics , 2007,
Abstract: Neutrino accompanied double beta-decay of Ge-76 can populate the ground state and the excited states of Se-76. While the decay to the ground state has been observed with a half-life of 1.74 +0.18 -0.16 10^21 years, decays to the excited states have not yet been observed. Nuclear matrix elements depend on details of the nuclear transitions. A measurement of the half-life of the transition considered here could help to reduce the uncertainties of the calculations of the nuclear matrix element for the neutrinoless double beta decay of Ge-76. This parameter relates the half-life of the process to the effective Majorana neutrino mass. The results of a feasibility study to detect the neutrino accompanied double beta-decay of Ge-76 to the excited states of Se-76 are presented in this paper. Segmented germanium detectors were assumed in this study. Such detectors, enriched in Ge-76 to a level of about 86%, will be deployed in the GERDA experiment located at the INFN Gran Sasso National Laboratory, Italy. It is shown that the decay of Ge-76 to the 1122 keV 0+ level of Se-76 can be observed in GERDA provided that the half-life of the process is in the range favoured by the present calculations which is 7.5 10^21 y to 3.1 10^23 y.
Off-line data processing and analysis for the GERDA experiment
M. Agostini,L. Pandola,P. Zavarise
Physics , 2011, DOI: 10.1088/1742-6596/368/1/012047
Abstract: GERDA is an experiment designed to look for the neutrinoless double beta decay of Ge-76. The experiment uses an array of high-purity germanium detectors, enriched in Ge-76, directly immersed in liquid argon. GERDA is presently operating eight enriched coaxial detectors (approximately 15 kg of Ge-76) and about 30 new custom-made enriched BEGe detectors will be deployed in the next phase (additional 20 kg of Ge-76). The paper describes the GERDA off-line analysis of the high-purity germanium detector data. Firstly we present the signal processing flow, focusing on the digital filters and on the algorithms used. Secondly we discuss the rejection of non-physical events and the data quality monitoring. The analysis is performed completely with the GERDA software framework (GELATIO), designed to support a multi-channel processing and to perform a modular analysis of digital signals.
GELATIO: a general framework for modular digital analysis of high-purity Ge detector signals
M. Agostini,L. Pandola,P. Zavarise,O. Volynets
Physics , 2011, DOI: 10.1088/1748-0221/6/08/P08013
Abstract: GELATIO is a new software framework for advanced data analysis and digital signal processing developed for the GERDA neutrinoless double beta decay experiment. The framework is tailored to handle the full analysis flow of signals recorded by high purity Ge detectors and photo-multipliers from the veto counters. It is designed to support a multi-channel modular and flexible analysis, widely customizable by the user either via human-readable initialization files or via a graphical interface. The framework organizes the data into a multi-level structure, from the raw data up to the condensed analysis parameters, and includes tools and utilities to handle the data stream between the different levels. GELATIO is implemented in C++. It relies upon ROOT and its extension TAM, which provides compatibility with PROOF, enabling the software to run in parallel on clusters of computers or many-core machines. It was tested on different platforms and benchmarked in several GERDA-related applications. A stable version is presently available for the GERDA Collaboration and it is used to provide the reference analysis of the experiment data.
Status of double beta decay experiments using isotopes other than Xe-136
Luciano Pandola
Physics , 2014, DOI: 10.1016/j.dark.2014.05.005
Abstract: Neutrinoless double beta decay is a lepton-number violating process predicted by many extensions of the standard model. It is actively searched for in several candidate isotopes within many experimental projects. The status of the experimental initiatives which are looking for the neutrinoless double beta decay in isotopes other than Xe-136 is reviewed, with special emphasis given to the projects that passed the R&D phase. The results recently released by the experiment GERDA are also summarized and discussed. The GERDA data give no positive indication of neutrinoless double beta decay of Ge-76 and disfavor in a model-independent way the long-standing observation claim on the same isotope. The lower limit reported by GERDA for the half-life of neutrinoless double beta decay of Ge-76 is T1/2 > 2.1e25 yr (90% C.L.), or T1/2 > 3.0e25 yr, when combined with the results of other Ge-76 predecessor experiments.
Off-line data quality monitoring for the GERDA experiment
P. Zavarise,M. Agostini,A. A. Machado,L. Pandola,O. Volynets
Physics , 2011, DOI: 10.1088/1742-6596/375/1/042028
Abstract: GERDA is an experiment searching for the neutrinoless {\beta}{\beta} decay of Ge-76. The experiment uses an array of high-purity germanium detectors, enriched in Ge-76, directly immersed in liquid argon. GERDA recently started the physics data taking using eight enriched coaxial detectors. The status of the experiment has to be closely monitored in order to promptly identify possible instabilities or problems. The on-line slow control system is complemented by a regular off-line monitoring of data quality. This ensures that data are qualified to be used in the physics analysis and allows to reject data sets which do not meet the minimum quality standards. The off-line data monitoring is entirely performed within the software framework GELATIO. In addition, a relational database, complemented by a web-based interface, was developed to support the off-line monitoring and to automatically provide information to daily assess data quality. The concept and the performance of the off-line monitoring tools were tested and validated during the one-year commissioning phase.
Observation of beta decay of In-115 to the first excited level of Sn-115
C. M. Cattadori,M. De Deo,M. Laubenstein,L. Pandola,V. I. Tretyak
Physics , 2004, DOI: 10.1016/j.nuclphysa.2004.10.025
Abstract: In the context of the LENS R&D solar neutrino project, the gamma spectrum of a sample of metallic indium was measured using a single experimental setup of 4 HP-Ge detectors located underground at the Gran Sasso National Laboratories (LNGS), Italy. A gamma line at the energy (497.48 +/- 0.21) keV was found that is not present in the background spectrum and that can be identified as a gamma quantum following the beta decay of In-115 to the first excited state of Sn-115 (9/2+ --> 3/2+). This decay channel of In-115, which is reported here for the first time, has an extremely low Q-value, Q = (2 +/- 4) keV, and has a much lower probability than the well-known ground state-ground state transition, being the branching ratio b = (1.18 +/- 0.31) 10^-6. This could be the beta decay with the lowest known Q-value. The limit on charge non-conserving beta decay of In-115 is set at 90% C.L. as tau > 4.1 10^20 y.
Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass
C. M. Cattadori,M. De Deo,M. Laubenstein,L. Pandola,V. I. Tretyak
Physics , 2005, DOI: 10.1134/S1063778807010140
Abstract: Recent observation of beta decay of 115-In to the first excited level of 115-Sn with an extremely low Q_beta value (Q_beta ~ 1 keV) could be used to set a limit on neutrino mass. To give restriction potentially competitive with those extracted from experiments with 3-H (~2 eV) and 187-Re (~15 eV), atomic mass difference between 115-In and 115-Sn and energy of the first 115-Sn level should be remeasured with higher accuracy (possibly of the order of ~1 eV).
Signal modeling of high-purity Ge detectors with a small read-out electrode and application to neutrinoless double beta decay search in Ge-76
M. Agostini,C. A. Ur,D. Budjá?,E. Bellotti,R. Brugnera,C. M. Cattadori,A. di Vacri,A. Garfagnini,L. Pandola,S. Sch?nert
Physics , 2010, DOI: 10.1088/1748-0221/6/03/P03005
Abstract: The GERDA experiment searches for the neutrinoless double beta decay of Ge-76 using high-purity germanium detectors enriched in Ge-76. The analysis of the signal time structure provides a powerful tool to identify neutrinoless double beta decay events and to discriminate them from gamma-ray induced backgrounds. Enhanced pulse shape discrimination capabilities of "Broad Energy Germanium" detectors with a small read-out electrode have been recently reported. This paper describes the full simulation of the response of such a detector, including the Monte Carlo modeling of radiation interaction and subsequent signal shape calculation. A pulse shape discrimination method based on the ratio between the maximum current signal amplitude and the event energy applied to the simulated data shows quantitative agreement with the experimental data acquired with calibration sources. The simulation has been used to study the survival probabilities of the decays which occur inside the detector volume and are difficult to assess experimentally. Such internal decay events are produced by the cosmogenic radio-isotopes Ge-68 and Co-60 and the neutrinoless double beta decay of Ge-76. Fixing the experimental acceptance of the double escape peak of the 2.614 MeV photon to 90%, the estimated survival probabilities at Qbb = 2.039 MeV are (86+-3)% for Ge-76 neutrinoless double beta decays, (4.5+-0.3)% for the Ge-68 daughter Ga-68, and (0.9+0.4-0.2)% for Co-60 decays.
Characterization of a broad energy germanium detector and application to neutrinoless double beta decay search in Ge-76
M. Agostini,E. Bellotti,R. Brugnera,C. M. Cattadori,A. D'Andragora,A. di Vacri,A. Garfagnini,M. Laubenstein,L. Pandola,C. A. Ur
Physics , 2010, DOI: 10.1088/1748-0221/6/04/P04005
Abstract: The performance of a 630g commercial broad energy germanium (BEGe) detector has been systematically investigated. Energy resolution, linearity, stability vs. high-voltage (HV) bias, thickness and uniformity of dead layers have been measured and found to be excellent. Special attention has been dedicated to the study of the detector response as a function of bias HV. The nominal depletion voltage being 3000V, the detector under investigation shows a peculiar behavior for biases around 2000V: in a narrow range of about 100V the charge collection is strongly reduced. The detector seems to be composed by two parts: a small volume around the HV contact where charges are efficiently collected as at higher voltage, and a large volume where charges are poorly collected. A qualitative explanation of this behavior is presented. An event-by-event pulse shape analysis based on A/E (maximum amplitude of the current pulse over the total energy released in the detector) has been applied to events in different energy regions and found very effective in rejecting non localized events. In conclusion, BEGe detectors are excellent candidates for the second phase of GERDA, an experiment devoted to neutrinoless double beta decay of Ge-76.
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