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Search Results: 1 - 10 of 471567 matches for " A. Di Vacri "
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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.
Characterization of a Nd-loaded organic liquid scintillator for neutrinoless double beta decay search of 150-Nd with a 10-ton scale detector
I. Barabanov,L. Bezrukov,C. Cattadori,N. Danilov,A. Di Vacri,A. Ianni,S. Nisi,F. Ortica,A. Romani,C. Salvo,O. Smirnov,E. Yanovich
Physics , 2009,
Abstract: Several liters of an organic liquid scintillator (LS) loaded with Nd have been made. We report on performances of this scintillator in terms of optical properties, radiopurity and light yield for a Nd concentration of 6.5 g/l. A possible application to search for the 150Nd neutrinoless double beta decay with a 10-ton scale LS detector is discussed together with further improvements.
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 and performances of new indium loaded organic liquid scintillators, based on novel indium carboxilate compounds
I. Barabanov,L. Bezrukov,C. Cattadori,N. Danilov,A. Di Vacri,N. Ferrari,V. Kornoukhov,Y. S. Krylov,N. Nesterova,S. Nisi,E. Yanovich
Physics , 2007,
Abstract: A novel formulation to dope organic liquid scintillators (OLS) with indium at concentrations up to 10% is presented: it is based on specific indium carboxylate compounds adequately synthesized. The produced In-OLS has been characterized: it has light yield 8500 ph/MeV at indium concentration 5.5% and light attenuation length of 2,5 m at wavelength of 430 nm. The scintillator properties were stable during all time of investigation (~ 1 years). The produced In-OLS is compared to other In-OLS formulations and shows superior performances. The developed methodic to metal dope OLS can be easily extended to other metals as Gd, Nd, Cd.
Highly sensitive gamma-spectrometers of GERDA for material screening: Part I
D. Budjá?,C. Cattadori,A. Gangapshev,W. Hampel,M. Heisel,G. Heusser,M. Hult,A. Klimenko,V. Kuzminov,M. Laubenstein,W. Maneschg,S. Nisi,S. Sch?nert,H. Simgen,A. Smolnikov,C. Tomei,A. di Vacri,S. Vasiliev,G. Zuzel
Physics , 2008,
Abstract: The GERDA experiment aims to search for the neutrinoless double beta-decay of 76Ge and possibly for other rare processes. The sensitivity of the first phase is envisioned to be more than one order of magnitude better than in previous neutrinoless double beta-decay experiments. This implies that materials with ultra-low radioactive contamination need to be used for the construction of the detector and its shielding. Therefore the requirements on material screening include high-sensitivity low-background detection techniques and long measurement times. In this article, an overview of material-screening laboratories available to the GERDA collaboration is given, with emphasis on the gamma-spectrometry. Additionally, results of an intercomparison of the evaluation accuracy in these laboratories are presented.
First search for double $β$ decay of dysprosium
P. Belli,R. Bernabei,F. Cappella,R. Cerulli,F. A. Danevich,S. d'Angelo,M. L. Di Vacri,A. Incicchitti,M. Laubenstein,S. S. Nagorny,S. Nisi,A. V. Tolmachev,V. I. Tretyak,R. P. Yavetskiy
Physics , 2011, DOI: 10.1016/j.nuclphysa.2011.04.003
Abstract: A search for double $\beta$ decay of dysprosium was realized for the first time with the help of an ultra low-background HP Ge $\gamma$ detector. After 2512 h of data taking with a 322 g sample of dysprosium oxide limits on double beta processes in $^{156}$Dy and $^{158}$Dy have been established on the level of $T_{1/2}\geq 10^{14}-10^{16}$ yr. Possible resonant double electron captures in $^{156}$Dy and $^{158}$Dy were restricted on a similar level. As a by-product of the experiment we have measured the radioactive contamination of the Dy$_2$O$_3$ sample and set limits on the $\alpha$ decay of dysprosium isotopes to the excited levels of daughter nuclei as $T_{1/2}\geq 10^{15} - 10^{17}$ yr.
Intrinsic neutron background of nuclear emulsions for directional Dark Matter searches
A. Aleksandrov,T. Asada,A. Buonaura,L. Consiglio,N. D'Ambrosio,G. De Lellis,A. Di Crescenzo,N. Di Marco,M. L. Di Vacri,S. Furuya,G. Galati,V. Gentile,T. Katsuragawa,M. Laubenstein,A. Lauria,P. F. Loverre,S. Machii,P. Monacelli,M. C. Montesi,T. Naka,F. Pupilli,G. Rosa,O. Sato,P. Strolin,V. Tioukov,A. Umemoto,M. Yoshimoto
Physics , 2015,
Abstract: Recent developments of the nuclear emulsion technology led to the production of films with nanometric silver halide grains suitable to track low energy nuclear recoils with submicrometric length. This improvement opens the way to a directional Dark Matter detection, thus providing an innovative and complementary approach to the on-going WIMP searches. An important background source for these searches is represented by neutron-induced nuclear recoils that can mimic the WIMP signal. In this paper we provide an estimation of the contribution to this background from the intrinsic radioactive contamination of nuclear emulsions. We also report the induced background as a function of the read-out threshold, by using a GEANT4 simulation of the nuclear emulsion, showing that it amounts to about 0.02 neutrons per year per kilogram, fully compatible with the design of a 10 kg$\times$year exposure.
Search for Rare Nuclear Decays with HPGe Detectors at the STELLA Facility of the LNGS
P. Belli,R. Bernabei,F. Cappella,R. Cerulli,F. A. Danevich,A. d'Angelo,S. d'Angelo,A. Di Marco,M. L. Di Vacri,A. Incicchitti,V. V. Kobychev,G. P. Kovtun,N. G. Kovtun,M. Laubenstein,S. Nisi,D. V. Poda,O. G. Polischuk,A. P. Shcherban,D. A. Solopikhin,J. Suhonen,A. V. Tolmachev,V. I. Tretyak,R. P. Yavetskiy
Physics , 2013, DOI: 10.1063/1.4856562
Abstract: Results on the search for rare nuclear decays with the ultra low background facility STELLA at the LNGS using gamma ray spectrometry are presented. In particular, the best T1/2 limits were obtained for double beta processes in 96Ru and 104Ru. Several isotopes, which potentially decay through different double beta decay channels, including also possible resonant double electron captures, were investigated for the first time (156Dy, 158Dy, 184Os, 192Os, 190Pt, 198Pt). Search for resonant absorption of solar 7Li axions in a LiF crystal gave the best limit for the mass of 7Li axions (< 8.6 keV). Rare alpha decay of 190Pt to the first excited level of 186Os (Eexc = 137.2 keV) was observed for the first time.
Discovery of the $^{151}$Eu $α$ decay
N. Casali,S. S. Nagorny,F. Orio,L. Pattavina,J. W. Beeman,F. Bellini,L. Cardani,I. Dafinei,S. Di Domizio,M. L. Di Vacri,L. Gironi,M. B. Kosmyna,B. P. Nazarenko,S. Nisi,G. Pessina,G. Piperno,S. Pirro,C. Rusconi,A. N. Shekhovtsov,C. Tomei,M. Vignati
Statistics , 2013, DOI: 10.1088/0954-3899/41/7/075101
Abstract: We report on the first compelling observation of $\alpha$ decay of $^{151}$Eu to the ground state of $^{147}$Pm. The measurement was performed using a 6.15 g Li$_6$Eu(BO$_3$)$_3$ crystal operated as a scintillating bolometer. The Q-value and half-life measured are: Q = 1948.9$\pm 6.9(stat.) \pm 5.1(syst.)$ keV, and T$_{1/2}=\left( 4.62\pm0.95(stat.)\pm0.68(syst.)\right) \times 10^{18}$ y . The half-life prediction of nuclear theory using the Coulomb and proximity potential model are in good agreement with this experimental result.
Performances and stability of a 2.4 ton Gd organic liquid scintillator target for antineutrino detection
I. R. Barabanov,L. B. Bezrukov,C. Cattadori,N. A. Danilov,A. Di Vacri,Yu. S. Krilov,L. Ioannucci,E. A. Yanovich,M. Aglietta,A. Bonardi,G. Bruno,W. Fulgione,E. Kemp,A. S. Malguin,A. Porta,M. Selvi,for the LVD Collaboration
Physics , 2008, DOI: 10.1088/1748-0221/5/04/P04001
Abstract: In this work we report the performances and the chemical and physical properties of a (2 x 1.2) ton organic liquid scintillator target doped with Gd up to ~0.1%, and the results of a 2 year long stability survey. In particular we have monitored the amount of both Gd and primary fluor actually in solution, the optical and fluorescent properties of the Gd-doped liquid scintillator (GdLS) and its performances as a neutron detector, namely neutron capture efficiency and average capture time. The experimental survey is ongoing, the target being continuously monitored. After two years from the doping time the performances of the Gd-doped liquid scintillator do not show any hint of degradation and instability; this conclusion comes both from the laboratory measurements and from the "in-tank" measurements. This is the largest stable Gd-doped organic liquid scintillator target ever produced and continuously operated for a long period.
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