[en] A novel broad-band mechanical impedance matching transformer, with applications to gravitational radiation detectors, is described. The transformer utilises transverse models in a tapered beam, or 'whip'. The whip is analysed by the WKB method, and the calculated wavefunction and amplitude gain are shown to be in reasonable agreement with experiment. (author)

[en] The growth of individual grains in commercial aluminium (AA5182) was measured in situ during a recrystallization heat treatment at 543 K including an intermediate cycle to room temperature and back on the three dimensional X-ray diffraction microscope at the European Synchrotron Radiation Facility. It is shown that the growth kinetics of the individual grains were not affected by the intermediate cycle to room temperature

[en] The pulse height weighting integration method for measuring H' (0.07) using a plastic scintillator has been developed through Monte Carlo simulations and laboratory tests. In order to design an optimal detector configuration, the parameters of input-window thickness and plastic scintillator thickness were investigated by EGS4 for their influences on the energy response for electrons. Based on the calculated deposited spectra in the plastic scintillator for electrons with various incident energies, a weighting function W(E), folded with the deposited energy spectra, was introduced in order to obtain a flat energy response in the low energy range. A constant response within ±3% was confirmed, by calculation, for electrons with energy >0.15 MeV. In addition, a preliminary experiment was performed using three beta sources (⁹⁰Sr-⁹⁰Y, ¹⁴⁷Pm, ²⁰⁴Tl) and the energy response within ±6% for beta rays with the maximum energy >0.22 MeV was obtained. Some factors causing uncertainties in the measurements are also discussed in this article. (authors)

[en] Aim: To evaluate the utility of T1 mapping on gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) for staging liver fibrosis. Materials and methods: This retrospective study was approved by the institutional review board and included 145 patients (mean age: 54 years old; 115 men and 30 women). Necro-inflammatory activity grade (G) and liver fibrosis stage (S) were histopathologically determined. T1 relaxation time and apparent diffusion coefficient (ADC) of the liver were measured and the reduction rate of the T1 relaxation time (Δ%) was calculated. T1 relaxation time measurements were compared with ADC values according to S/G scores. Results: Unenhanced hepatobiliary phase (HBP) and Δ% of T1 relaxation times showed significant correlations with S/G scores (rho: 0.28, 0.51, −0.35 for the S score, 0.26, 0.39, −0.26 for the G score, respectively, p<0.05). ADC values showed significant correlation with the S score (rho: −0.17, p=0.04) and did not correlate significantly with the G score (rho: −0.07, p=0.39). The areas under receiver operator characteristics (AUC) curve of unenhanced HBP, Δ% T1 relaxation time, and the ADC value were 0.68, 0.82, 0.71, 0.61 for the identification of S≥3, and 0.63, 0.68, 0.62, 0.52 for the identification of G≥3, respectively. The HBP T1 relaxation time was better than that of ADC for identification of S≥3 (p=0.0005) and G≥3 (p=0.014). Conclusions: The HBP T1 relaxation time measurement on gadoxetic acid-enhanced MRI images might be a potential biomarker in the staging of hepatic fibrosis, and was more accurate than the ADC measurement. -- Highlights: •We compared the results of T1 relaxation time measurement with DWI-ADC measurement on evaluating the liver fibrosis stages(S)/necroinflammatory activity grade(G) scores. •T1 relaxation time measurements on Gadoxetic acid-enhanced MR imaging might be a potential biomarker in staging of hepatic fibrosis. •T1 relaxation time measurements on Gadoxetic acid-enhanced MR imaging were more accuracy than ADC measurement

[en] This paper proposes a numerical model of the dynamic time over threshold (DTOT) method for semi-Gaussian signals. The parameters are optimized accordingly in the design of a prototype DTOT circuit. A photomultiplier tube was coupled to a 2-inch LaBr₃ scintillator and connected to a charge sensitive preamplifier. The signal was semi-Gaussian shaped and sent to the DTOT circuit. The feasibility of the technique has been verified by the experimental results, which achieve 2.3% integral nonlinearity and 7-bit dynamic range.

[en] Muon tomography, as a novel method of radiography, utilizes the multiple Coulomb scattering property of muons from cosmic rays to discriminate materials. Researchers around the world have been developing various detection systems and image reconstruction algorithms for muon tomography applications, such as in the fields of nuclear reactor monitoring and cargo inspection for contrabands. This paper studies the principle of image reconstruction in muon tomography. The implementation and comparison of some popular algorithms with our simulation dataset are presented, together with ideas regarding potential improvements in image quality and material discrimination performance.

[en] A muon tomography facility has been built in Tsinghua University. Because of the low flux of cosmic muon, an encoding readout method, based on the fine-fine configuration, was implemented for the 2880 channels induced signals from the Multi-gap Resistive Plate Chamber (MRPC) detectors. With the encoding method, the number of the readout electronics was dramatically reduced and thus the complexity and the cost of the facility was reduced, too. In this paper, the details of the encoding method, and the overall readout system setup in the muon tomography facility are described. With the commissioning of the facility, the readout method works well. The spatial resolution of all MRPC detectors are measured with cosmic muon and the preliminary imaging result are also given

[en] Single crystals of Erbium (Er) doped La3Ga5SiO14 (LGS) have been grown along c-axis by using the Czochralski method. The absorption and fluorescence spectra of LGS: Er3+ single crystals have been measured and analyzed according to the Judd-Ofelt theory. When applied, the following spectral parameters have been obtained: intensity parameters Ωt, Ω2=2.741674 x 10-20 cm2, Ω4=0.66934 x 10-20 cm2 and Ω6=0.592591 x 10-20 cm2, radiative transition probabilities AJ,J'', PJ,J''. The radiative lifetime of levels 4I13/2, 4H9/2, 4S3/2 are 11.333 ms, 0.447 ms and 0.704 ms, respectively. The fluorescence branching ratios and the integrated emission cross sections are also calculated. The results suggest that LGS: Er crystals have potential applications as a laser material. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

[en] Epithelioid hepatic angiomyolipoma (Epi-HAML) is a rare benign mesenchymal tumor with malignant potential. Most of Epi-HAML contains no or only a minimal amount of adipose tissue and poses a diagnostic challenge. Central vessels are characteristic imaging finding of Epi-HAML, which usually were displayed by dynamic contrast imaging. In this paper, we displayed the central vessels of Epi-HAML invisible on conventional MR images using a new developed abdominal susceptibility-weighted imaging (SWI). To the best of our knowledge, this is the first description for the role of SWI in characterization of Epi-HAML

[en] With the development of high-speed readout electronics, the digital pulse shape discrimination (PSD) methods have attracted the attention of more researchers, especially in the field of high energy physics and neutron detection. How to choose a PSD algorithm and corresponding data acquisition system (DAQ) naturally becomes a critical problem to settle down for the detection system designers. In this paper, the relationship between the classification performance of different PSD algorithms and digitizers' sampling properties (including sampling rate and the effective number of bits) has been researched based on $\mathrm{L}\mathrm{a}\mathrm{B}{\mathrm{r}}_3$:Ce scintillation detectors. A self-developed integrated digitizer configured with five different ADCs and a WavePro 404HD oscilloscope were deployed to digitize the waveforms from $\mathrm{L}\mathrm{a}\mathrm{B}{\mathrm{r}}_3$:Ce scintillators. Moreover, three PSD methods, charge comparison method (CCM), least square for classification method (LS) and Fisher's linear discriminant analysis (LDA), based on linear model were applied to discriminate the alpha signals from the intrinsic isotope ${}^{227}$Ac. With the LS method and a 125 MSPS 14-Bit ADC, the FoM value was 1.424$\pm <!--\; ??\; -->$0.042, which is similar to the result from LDA but 31% better than the result of CCM. The discrimination results showed that the performances of LS and LDA are less affected by the sampling rate with respect to the CCM method, which reflects in a better PSD capability. The results of this paper can help the developers of detector systems to make a trade-off among sampling properties, desirable discrimination results and the cost of systems.