The accurate calibration of photomultiplier tubes is critical in a wide variety of applications for which it is necessary to know the absolute number of detected photons or precisely determine the ...resolution of the signal. Conventional calibration methods rely on fitting the photomultiplier response to a low intensity light source with analytical approximations to the single photoelectron distribution. We show that this approach often leads to biased estimates due to an inability to model the full distribution accurately, especially at low charge values. We present a simple statistical method to extract the relevant single photoelectron calibration parameters (first two central moments) without making any assumptions about the underlying single photoelectron distribution. We illustrate the use of this method through the calibration of a Hamamatsu R11410 photomultiplier tube and study the accuracy and precision of the method using Monte Carlo simulations. The method is found to have significantly reduced bias compared to conventional methods and works under a wide range of light intensities, making it suitable for the simultaneous calibration of large arrays of photomultiplier tubes where uniform illumination may not be possible.
Cosmogenic activation of silicon Saldanha, R.; Thomas, R.; Tsang, R. H. M. ...
Physical review. D,
11/2020, Letnik:
102, Številka:
10
Journal Article
Recenzirano
Odprti dostop
The production of 3H, 7Be, and 22Na by interactions of cosmic-ray particles with silicon can produce radioactive backgrounds in detectors used to search for rare events. Through controlled ...irradiation of silicon CCDs and wafers with a neutron beam that mimics the cosmic-ray neutron spectrum, followed by direct counting, we determined that the production rate from cosmic-ray neutrons at sea level is ( 112 ± 24 ) atoms / ( kg day ) for 3H, ( 8.1 ± 1.9 ) atoms / ( kg day ) for 7Be, and ( 43.0 ± 7.2 ) atoms / ( kg day ) for 22Na. Complementing these results with the current best estimates of activation cross sections for cosmic-ray particles other than neutrons, we obtain a total sea-level cosmic-ray production rate of ( 124 ± 25 ) atoms / ( kg day ) for 3H, ( 9.4 ± 2.0 ) atoms / ( kg day ) for 7Be, and ( 49.6 ± 7.4 ) atoms / ( kg day ) for 22Na. These measurements will help constrain background estimates and determine the maximum time that silicon-based detectors can remain unshielded during detector fabrication before cosmogenic backgrounds impact the sensitivity of next-generation rare-event searches.
In this article, a new methodology for sensitivity analysis evaluation of electric potential distribution near transmission lines (TLs) is proposed. The potential is modeled by the finite element ...method, and the sensitivity related to cable positions is obtained using the adjoint method, and thus the objective function's sensitivity is adopted during the optimization process using a multiple cuts' ellipsoid method to get new geometries with high surge impedance loading (SIL). The sensitivities of a large number of conductors by phase are obtained with high precision and very low computational cost, using adjoint sensitivities, which are not dependent on the number of design variables. The approximation using central finite differences (CFDs) to calculate the sensitivity is used for comparisons and validation. Therefore, with this methodology, the finite element method (FEM) model of TLs can be used during the optimization process without compromising the required computational processing time.
Liquid Argon Time Projection Chambers are planned to comprise a central role in the future of the U.S. High Energy Physics neutrino program. In particular, this detector technology will form the ...basis for the 40 kton Deep Underground Neutrino Experiment (DUNE) . In this paper we take as a starting point the dual phase far detector design proposed by the DUNE experiment and ask what changes are necessary to allow one of the four 10 kt modules to be sensitive to heavy Weakly Interacting Massive Particle (WIMP) dark matter. We show that with control over backgrounds and the use of low radioactivity argon, which may be commercially available on that timescale, along with a significant increase in light detection, one DUNE-like module gives a competitive WIMP detection sensitivity, particularly above a dark matter mass of 100 GeV.
This paper presents a multiobjective approach for the design of electrical distribution networks. The objectives are defined as a monetary cost index (including installation cost and energy losses ...cost) and a system failure index. The true Pareto-optimal solutions are found with a multiobjective genetic algorithm that employs an efficient variable encoding scheme and some problem-specific mutation and crossover operators. Results based on 21- and 100-bus systems are presented. The information gained from the Pareto-optimal solution set is shown to be useful for the decision-making stage of distribution network evolution planning.
We present a novel application of machine learning techniques to optimize the design of a radiation detection system. A decision tree-based algorithm is described which greedily optimizes ...partitioning of energy depositions based on a minimum detectable concentration metric – appropriate for radiation measurement. We apply this method to the task of optimizing sensitivity to radioxenon decays in the presence of a high rate of radon-progeny backgrounds (i.e., assuming no physical radon removal by traditional gas separation techniques). Assuming other backgrounds are negligible, and considering sensitivity to each xenon isotope separately (neglecting interference between isotopes), we find that, in general, high resolution readout and high spatial segmentation yield little additional capability to discriminate against radon backgrounds compared to simpler detector designs.
•Decision Trees provide interpretable results to guide radiation detector design.•Decision Trees to minimize MDC outperforms the standard method.•The tool identifies regions of interest similar to human-driven analyses.•Higher-order coincidences do not improve radioXe sensitivity vs radon background.•Energy resolution has a small effect on radioxenon sensitivity vs radon background.
Lipoabdominoplasty Saldanha, Osvaldo R; Federico, Rodrigo; Daher, Presper F ...
Plastic and reconstructive surgery (1963)
124, Številka:
3
Journal Article
Recenzirano
Abdominoplasty is one of the most common aesthetic operations. Wide bibliographic research has revealed that there is a safe method whereby two techniques--liposuction and abdominoplasty--can be ...associated in the same procedure. The authors present a new abdominoplasty technique combining a selective undermining with complete abdominal liposuction.
The authors standardized steps with which to perform a safe association of traditional abdominoplasty with liposuction of the entire abdomen and infracostal areas. Using selective undermining, it is possible to preserve at least 80 percent of the blood supply in the abdominal wall, causing little nervous trauma, preserving the great majority of the lymphatic vessels, and resulting in few complications compared with traditional abdominoplasty, including post-bariatric surgery procedures. In this study, lipoabdominoplasty was performed on 445 patients: eight male patients and 437 female patients, from 2000 to 2007.
The authors consider the results good and excellent, especially regarding patient evaluation, better body contour, abdominal rejuvenation, shorter scars, the form of the umbilicus, and a decrease in the abdominal measures.
With a progressive adaptation of this technique, it is possible to achieve a harmonious body contour using a safe liposuction method on the abdominal and costal areas, with fast recovery and good to excellent results.
This paper presents a multi-objective evolutionary algorithm based on decomposition (MOEA/D) to design broadband optimal Yagi-Uda antennas. A multi-objective problem is formulated to achieve maximum ...directivity, minimum voltage standing wave ratio and maximum front-to-back ratio. The algorithm was applied to the design of optimal 3 to 10 elements Yagi-Uda antennas, whose optimal Pareto fronts are provided in a single picture. The multi-objective problem is decomposed by Chebyshev decomposition, and it is solved by differential evolution (DE) and Gaussian mutation operators in order to provide a better approximation of the Pareto front. The results show that the implemented MOEA/D is efficient for designing Yagi-Uda antennas.
In this paper we propose a new distribution of Gaussian points to compute the weak form integrals of the Generalized Finite Element Method (GFEM). The relevance of this new distribution is the ...possibility of evaluating the integrals of oscillatory functions inside the reference triangle in an alternate way. A simple scheme of relocation of the quadrature points allows to improve the efficacy of the method. A wave propagation problem is solved with the proposed technique and its performance is compared to conventional and other existing proposals. In addition, we propose a new distribution of Gaussian points to the tetrahedral reference element
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