187 research outputs found
SOME NEW RESULTS ON SEMIINSULATING GAAS DETECTORS FOR LOW-ENERGY X-RAYS
No full textGaAs is a semiconductor suitable for room temperature X-ray detection but hitherto has suffered from incomplete charge collection and is affected by noise. Recent GaAs detectors made with LEC material have shown improved charge collection efficiency and energy resolution. In this paper we describe the fabrication process and present the results obtained with 80 mu m thick pad detectors
Experimental study of LEC GaAs detectors for X-ray digital radiography
No full textIn previous studies, various semi-insulating LEC GaAs crystals were irradiated with photons in the diagnostic energy range (20-100 keV), in view of a possible application in digital radiography. Solid-state and irradiation measurements, together with Monte Carlo simulations, have indicated good candidates for this application among the crystals we have investigated. In this paper we present results concerning the detection characteristics (detection efficiency, charge-collection efficiency and energy resolution as functions of the bias voltage) of one of these materials and the images obtained by a pixel detector made on the same material and a bump-bonded electronic system. RI Cola, Adriano/G-2379-201
Purposeless Restraints: Fourteenth Amendment Rationality Scrutiny and the Constitutional Review of Prison Sentences
No full textThis Article presents an analysis and defense of the Supreme Court\u27s current Eighth Amendment case law on prison sentencing. I argue that in the pivotal cases of Ewing v. California and Harmelin v. Michigan, a plurality of the Supreme Court has assimilated Eighth Amendment review of individual prison sentences to rationality review of state action under the Fourteenth Amendment\u27s due process clause. When the cases are read rightly, it becomes clear that Eighth Amendment review does not really ask whether a sentence is grossly disproportionate, as the Court has asserted; rather, it seeks to identify arbitrary and capricious prison sentences that suggest a procedural defect in the sentencing process. I defend this doctrine on the grounds of original understanding, stare decisis, neutral interpretation, and normative federalism values. Finally, I show how an interpretation of Eighth Amendment prison sentencing review as rationality review can be squared with the Supreme Court\u27s decisions involving constitutional proportionality review of other noncapital sanctions such as fines, punitive damages, and conditions of confinement
A fuzzy logic approach to computer software source code authorship analysis
No full textSoftware source code authorship analysis has become an important area in recent years with promising applications in both the legal sector (such as proof of ownership and software forensics) and the education sector (such as plagiarism detection and assessing style). Authorship analysis encompasses the sub-areas of author discrimination, author characterization, and similarity detection (also referred to as plagiarism detection). While a large number of metrics have been proposed for this task, many borrowed or adapted from the area of computational linguistics, there is a difficulty with capturing certain types of information in terms of quantitative measurement. Here it is proposed that existing numerical metrics should be supplemented with fuzzy-logic linguistic variables to capture more subjective elements of authorship, such as the degree to which comments match the actual source code’s behavior. These variables avoid the need for complex and subjective rules, replacing these with an expert’s judgement. Fuzzy-logic models may also help to overcome problems with small data sets for calibrating such models. Using authorship discrimination as a test case, the utility of objective and fuzzy measures, singularly and in combination, is assessed as well as the consistency of the measures between counters
A fuzzy logic approach to computer software source code authorship analysis
No full textSoftware source code authorship analysis has become an important area in recent years with promising applications in both the legal sector (such as proof of ownership and software forensics) and the education sector (such as plagiarism detection and assessing style). Authorship analysis encompasses the sub-areas of author discrimination, author characterization, and similarity detection (also referred to as plagiarism detection). While a large number of metrics have been proposed for this task, many borrowed or adapted from the area of computational linguistics, there is a difficulty with capturing certain types of information in terms of quantitative measurement. Here it is proposed that existing numerical metrics should be supplemented with fuzzy-logic linguistic variables to capture more subjective elements of authorship, such as the degree to which comments match the actual source code’s behavior. These variables avoid the need for complex and subjective rules, replacing these with an expert’s judgement. Fuzzy-logic models may also help to overcome problems with small data sets for calibrating such models. Using authorship discrimination as a test case, the utility of objective and fuzzy measures, singularly and in combination, is assessed as well as the consistency of the measures between counters
Image quality of Medipix2 assemblies with silicon detectors of two different thicknesses
No full textCharge collection efficiency of irradiated silicon detector operated at cryogenic temperatures
No full textThe charge collection efficiency (CCE) of heavily irradiated silicon diode detectors was investigated at temperatures between 77 and 200 K. The CCE was found to depend on the radiation dose, bias voltage value and history, temperature, and bias current generated by light. The detector irradiated to the highest fluence 2 x 10(15) n/cm(2) yields a MIP signal of at least 15000 e(-) both at 250 V forward bias voltage, and at 250 V reverse bias voltage in the presence of a light-generated current. The "Lazarus effect" was thus shown to extend to fluences at least ten times higher than was previously studied
On the Properties of Slow MHD Sausage Waves Within Small-Scale Photospheric Magnetic Structures
No full textThe presence of magnetoacoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we aim to identify properties of the observed magnetoacoustic waves and study the background properties of magnetic structures within the lower solar atmosphere. Using the Dutch Open Telescope and Rapid Oscillations in the Solar Atmosphere instruments, we captured two series of high-resolution intensity images with short cadences of two isolated magnetic pores. Combining wavelet analysis and empirical mode decomposition (EMD), we determined characteristic periods within the cross-sectional (i.e., area) and intensity time series. Then, by applying the theory of linear magnetohydrodynamics (MHD), we identified the mode of these oscillations within the MHD framework. Several oscillations have been detected within these two magnetic pores. Their periods range from 3 to 20 minutes. Combining wavelet analysis and EMD enables us to confidently find the phase difference between the area and intensity oscillations. From these observed features, we concluded that the detected oscillations can be classified as slow sausage MHD waves. Furthermore, we determined several key properties of these oscillations such as the radial velocity perturbation, the magnetic field perturbation, and the vertical wavenumber using SMS. The estimated range of the related wavenumbers reveals that these oscillations are trapped within these magnetic structures. Our results suggest that the detected oscillations are standing harmonics, and this allows us to estimate the expansion factor of the waveguides by employing SMS. The calculated expansion factor ranges from 4 to 12
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