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Search Results: 1 - 10 of 219538 matches for " C. Cattadori "
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A new approach to the front-end readout of cryogenic ionization detectors
C. Cattadori,B. Gallese,A. Giachero,C. Gotti,M. Maino,G. Pessina
Physics , 2011, DOI: 10.1088/1748-0221/6/05/P05006
Abstract: We present a novel approach to the readout of ionization detectors. The solution allows to minimize the number of components and the space occupation close to the detector. This way a minimal impact is added on the radioactive background in those experiments where very low signal rates are expected, such as GERDA and MAJORANA. The circuit consists in a JFET transistor and a remote second stage. The DC feedback path is closed using a diode. Two signal cables are only necessary for biasing and readout.
GeFRO: a New Charge Sensitive Amplifier Design with a Minimal Number of Front-end Components
L. Cassina,C. Cattadori,A. Giachero,C. Gotti,M. Maino,G. Pessina
Physics , 2013,
Abstract: A new approach was developed for the design of front-end circuits for semiconductor radiation detectors. The readout scheme consists of a first stage made of only a few components located close to the detector, and of a remote second stage located far from the detector, several meters away. The second stage amplifies the signals from the first stage and closes the feedback loop to discharge the input node after each event. The circuit has two outputs: one gives a "fast" signal, with a bandwidth larger than 20 MHz, allowing to preserve the high frequency components of the detector signals, which may be useful for timing measurements, pile-up rejection or pulse shape discrimination. The second output gives a "slow" signal, whose gain depends only on the value of the feedback capacitor, as happens with a classic charge sensitive amplifier, allowing to obtain higher resolution and lower drift. The prototype was named GeFRO for Germanium front-end, and was tested with a BEGe detector from Canberra. The wide bandwidth of the "fast" signal gave a timing resolution of the order of 20 ns. The noise of the circuit at the "slow" output after a 10 us Gaussian shaping was close to 160 electrons RMS with an input capacitance of 26 pF.
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).
Evolutionary History and Attenuation of Myxoma Virus on Two Continents
Peter J. Kerr,Elodie Ghedin,Jay V. DePasse,Adam Fitch,Isabella M. Cattadori,Peter J. Hudson,David C. Tscharke,Andrew F. Read,Edward C. Holmes
PLOS Pathogens , 2012, DOI: 10.1371/journal.ppat.1002950
Abstract: The attenuation of myxoma virus (MYXV) following its introduction as a biological control into the European rabbit populations of Australia and Europe is the canonical study of the evolution of virulence. However, the evolutionary genetics of this profound change in host-pathogen relationship is unknown. We describe the genome-scale evolution of MYXV covering a range of virulence grades sampled over 49 years from the parallel Australian and European epidemics, including the high-virulence progenitor strains released in the early 1950s. MYXV evolved rapidly over the sampling period, exhibiting one of the highest nucleotide substitution rates ever reported for a double-stranded DNA virus, and indicative of a relatively high mutation rate and/or a continually changing selective environment. Our comparative sequence data reveal that changes in virulence involved multiple genes, likely losses of gene function due to insertion-deletion events, and no mutations common to specific virulence grades. Hence, despite the similarity in selection pressures there are multiple genetic routes to attain either highly virulent or attenuated phenotypes in MYXV, resulting in convergence for phenotype but not genotype.
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 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 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.
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