816 research outputs found
Optimum Filter Synthesis with DPLMS Method for Energy Reconstruction
Optimum filters are granted increasing recognition as valuable tools for
parametric estimation in many scientific and technical fields. The DPLMS
method, introduced some twenty years ago, is effective among the synthesis
algorithms since it derives the optimum filters directly from the experimental
signal and noise waveforms. Two new extensions of the DPLMS method are here
presented. The first one speeds up the synthesis phase and improves the energy
estimation by synthesizing optimum filters with automatically designed flat-top
length. The second one improves the quality of parameter estimation in
multi-channel systems by taking advantage of the inter-channel noise
correlation properties. The theoretical and functional aspects behind the DPLMS
method for optimum filter synthesis are first recalled and illustrated in more
detail. The two new DPLMS extensions are subsequently introduced from the
theoretical viewpoint and more thoroughly considered from the applicative
perspective. The DPLMS optimum filters have been applied first to simulated
signals with various amounts and characteristics of superimposed noise and then
to the experimental waveforms acquired from a solid-state Ge detector. The
results obtained are considered from both the absolute viewpoint and in
comparison with those of more traditional, suboptimal filters. The results
demonstrate the effectiveness of the two new DPLMS extensions. For
single-channel energy estimations, the optimum filters provide comparatively
better results than the other filters. The DPLMS multi-channel optimum filters
further enhance the quality of the estimations, compared to single-channel
optimum filters, with non-negligible inter-channel noise correlation. The
effectiveness and robustness of the DPLMS method in synthesizing high-quality
filters for energy estimation will be tested soon within leading-edge
multi-channel physics experiments.Comment: 15 pages, 13 figure
Time-domain Simulation of electronic noises
In this paper, a procedure is proposed to computer simulate the electronic noise of ionizing-radiation spectrometers. The viewpoint of the simulator is the output of the preamplifier, with or without an anti-aliasing filter, just in front of the ADC. Examples are given for the case of segmented high purity Germanium detectors (HPGe). The method makes use of the fractional calculus basics. A software procedure provides the noisy waveform as a function of the fundamental electrical-physical parameters of the system, including: detector capacitance, detector leakage current, feedback resistor, 1/f-noise coefficient of the input transistor, temperature of the preamplifier input devices. The ADC quantization noise is also included in the simulation
Impact of an asbestos cement factory on mesothelioma incidence: Global assessment of effects of occupational, familial, and environmental exposure
Few studies have examined the incidence of malignant mesothelioma (MM) associated with distinct sources of asbestos exposure (occupational, familial, or environmental). We assessed the impact of asbestos exposure—global and by source—on the incidence of MM in Broni, an Italian town in which an asbestos cement factory once operated (1932–1993). Based on data collected by the Lombardy Mesothelioma Registry, we calculated the number of observed and expected MM cases among workers, their cohabitants, and people living in the area in 2000–2011. We identified 147 MM cases (17.45 expected), 138 pleural and nine peritoneal, attributable to exposure to asbestos from the factory. Thirty-eight cases had past occupational exposure at the factory (2.33 expected), numbering 32 men (26 pleural, six peritoneal) and six women (four pleural, two peritoneal). In the families of the workers, there were 37 MM cases (4.23 expected), numbering five men (all pleural) and 32 women (31 pleural, one peritoneal). Among residents in Broni or in the adjacent/surrounding towns, there were 72 cases of pleural MM (10.89 expected), numbering 23 men and 49 women. The largest MM excess was found in the towns of Broni (48 observed, 3.68 expected) and Stradella (16 observed, 1.85 expected). This study documents the large impact of the asbestos cement factory, with about 130 excess MM cases in a 12-year period. The largest MM burden was among women, from non-occupational exposure. Almost half of the MM cases were attributable to environmental exposure. Keywords: Asbestos, Mesothelioma, Cancer incidence, Occupational exposure, Familial exposure, Environmental exposur
Sinonasal cancer and occupational exposure in a population-based registry.
We examined occupational exposures among subjects with sinonasal cancer (SNC) recorded in a population-based registry in the Lombardy Region, the most populated and industrialized Italian region. The registry collects complete clinical information and exposure to carcinogens regarding all SNC cases occurring in the population of the region. In the period 2008-2011, we recorded 210 SNC cases (137 men, 73 women). The most frequent occupational exposures were to wood (44 cases, 21.0%) and leather dust (29 cases, 13.8%), especially among men: 39 cases (28.5%) to wood and 23 cases (16.8%) to leather dust. Exposure to other agents was infrequent (<2%). Among 62 subjects with adenocarcinoma, 50% had been exposed to wood dust and 30.7% to leather dust. The proportions were around 10% in subjects with squamous cell carcinoma and about 20% for tumors with another histology. The age-standardized rates (Ă—100,000 person-years) were 0.7 in men and 0.3 in women. Complete collection of cases and their occupational history through a specialized cancer registry is fundamental to accurately monitor SNC occurrence in a population and to uncover exposure to carcinogens in different industrial sectors, even those not considered as posing a high risk of SNC, and also in extraoccupational settings
Incidence of mesothelioma in Lombardy, Italy: exposure to asbestos, time patterns and future projections
Objectives In Italy, asbestos has been extensively used from 1945 to 1992. We evaluated the impact of exposure to asbestos on occurrence of malignant mesothelioma (MM) in the Lombardy Region, Northwest Italy, the most populated and industrialised Italian region. Methods From the Lombardy Mesothelioma Registry, we selected all incident cases of MM diagnosed between 2000 and 2012. We described sources of exposure to asbestos and examined time trends of MM rates. Using Poisson age-cohort models, we derived projections of burden of MM in the Lombardy population for the period 2013-2029. Results In 2000-2012, we recorded 4442 cases of MM (2850 men, 1592 women). Occupational exposure to asbestos was more frequent in men (73.6%) than in women (38.2%). Non-occupational exposure was found for 13.6% of women and 3.6% of men. The average number of cases of MM per year was still increasing (+3.6% in men, +3.3% in women). Incidence rates were still increasing in individuals aged 65+ years and declining in younger people. A maximum of 417 cases of MM (267 men, 150 women) are expected in 2019. We forecast there will be 6832 more cases (4397 in men, 2435 in women) in the period 2013-2029, for a total of 11274 cases of MM (7247 in men, 4027 in women) in 30years. Conclusions This study documented a high burden of MM in both genders in the Lombardy Region, reflecting extensive occupational (mainly in men) and non-occupational (mainly in women) exposure to asbestos in the past. Incidence rates are still increasing; a downturn in occurrence of MM is expected to occur after 2019
Characterization of Large Volume 3.5 x 8 inches LaBr3:Ce Detectors
The properties of large volume cylindrical 3.5 x 8 inches (89 mm x 203 mm)
LaBr3:Ce scintillation detectors coupled to the Hamamatsu R10233-100SEL
photo-multiplier tube were investigated. These crystals are among the largest
ones ever produced and still need to be fully characterized to determine how
these detectors can be utilized and in which applications. We tested the
detectors using monochromatic gamma-ray sources and in-beam reactions producing
gamma rays up to 22.6 MeV; we acquired PMT signal pulses and calculated
detector energy resolution and response linearity as a function of gamma-ray
energy. Two different voltage dividers were coupled to the Hamamatsu
R10233-100SEL PMT: the Hamamatsu E1198-26, based on straightforward resistive
network design, and the LABRVD, specifically designed for our large volume
LaBr3:Ce scintillation detectors, which also includes active semiconductor
devices. Because of the extremely high light yield of LaBr3:Ce crystals we
observed that, depending on the choice of PMT, voltage divider and applied
voltage, some significant deviation from the ideally proportional response of
the detector and some pulse shape deformation appear. In addition, crystal
non-homogeneities and PMT gain drifts affect the (measured) energy resolution
especially in case of high-energy gamma rays. We also measured the time
resolution of detectors with different sizes (from 1x1 inches up to 3.5x8
inches), correlating the results with both the intrinsic properties of PMTs and
GEANT simulations of the scintillation light collection process. The detector
absolute full energy efficiency was measured and simulated up to gamma-rays of
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