Response of CR39 detector to 5 A GeV Si14+ ions and measurement of total charge changing cross-section

In the present work, response of CR39 track etch detector was obtained by cone-height measurement technique. CR39 track etch detector was used to identify the incident charged particles and their fragments by the measurements of cone-height of tracks using an optical microscope DM6000 M and automated image analyzer system installed with Leica QWin Plus software. The CR39 detector was calibrated and the response points were fitted with a linear relation and all the points are within the limits of the experimental errors. The charge resolution of the detector was calculated to be 0.2e. The response function is obtained and fitted with a linear relation which is good throughout Z/β=6.1–14.1. The experimental value of the total charge changing cross-section of 5 A GeV Si¹⁴⁺ ion beam in polyethylene and CR39 combined target is σ_tot=(734±128) mb. The total charge changing cross-section is compared with the experimental results of others based on cone base-area measurement technique and also fitted by the Bradt–Peters geometrical cross-section.     

An Accurate Equation for the Electrolytic Conductivity of Potassium Chloride Solutions

An empirical equation has been developed to model the electrolytic conductivity of potassium chloride (KCl) solutions over the temperature range 0 to 55 °C (ITS-90) and molality concentrations from 0 to 5 mol⋅kg⁻¹ (H₂O). The National Institute of Standards and Technology (NIST) Demal values are treated as the defining data and selected historical data provided further data. Changes in the definition of the ohm, liter and temperature scales have been identified and the historical data were converted to modern units. The accuracy of the equation is estimated to be equal to 0.03% as suggested by NIST as the accuracy of these data.     

Calibration in chemical measurement processes. II. A methodological approach

This article discusses the common terms related to chemical measurement processes, the different methodologies of calibration (which are not always well established) and the role of chemical standards. General classifications of reference materials and their use in the calibration process are clarified. Related features, such as recovery studies or screening and corrections of matrix systematic errors, are also considered, and guidelines concerning experimental design and verification of the calibration are given.     

Laser ablation of powdered samples and analysis by means of laser-induced breakdown spectroscopy

The presented work proves the capacities of laser-induced breakdown spectroscopy (LIBS) as a fast, universal, and versatile technique for analysis of complex materials as ceramics. This paper reports on the analysis of ceramic raw materials (brick clays and kaolin) submitted to laser ablation in the form of pressed pellets. Spectrographic study was provided by standard single-pulse LIBS technique and orthogonal reheating double-pulse LIBS. It was found that both methods are comparable in terms of analytical performance, if adequate experimental parameters and signal detection systems are used.     

软X光多层镜反射率的标定与修正

在北京同步辐射装置上,利用3W1B 束线得到了21° B4C/Si,21° B4C /Mo,10° Cr/Ti,15° B4C/W,10° B4C/W以及6.86° B4C/W等多层镜在50～1500 eV能段上的反射率标定曲线.分析了标定结果的不确定度,计算得到多层镜的积分衍射效率,并修正了标定结果.     

痕量元素ICP-MS测定基体干扰研究及外标法应用

研究了以K、Na、Ca、Mg为主要基体组分时,ICP-MS测定多元素时的干扰情况,结果表明在基体〈0.1%,基体对测定结果无明显干扰。ICP-MS外标法对天然地表水,地下水中土壤,水系沉积物,植物进行测定,在水样测定中,盐分〈500mg/L,外标法与内标法及AAN,ICP-AES测定结果一致,土壤,水系沉积物,植物测定,当基体〈0.1%外标法与内标法测定值一致。     

New calibrations and time stability of the response of the INTERCAST CR-39

We present new calibrations of different production batches (from 1989 to 1999) of the INTERCAST CR-39, using the BNL-AGS 1 A GeV iron beam. The comparison with previous results, obtained with the 158 A GeV lead beam from the CERN-SPS shows that, while each production batch has a different calibration curve (mainly due to minor differences in the production conditions), the aging effect is negligible. We also tested the dependence of the CR-39 response from the time elapsed between exposure and analysis (fading effect). The fading effect, if present, is less then 10%. It may be compatible with the experimental uncertainties on the bulk etching rate v_B.     

Simultaneous calibration of TLDs using the ICRU slab and photon beams

Adoption of the ICRU slab enables several dosimeters to be calibrated simultaneously. In order to allow use of identical conversion coefficients, these dosimeters should be exposed to the same irradiation conditions to within a given tolerance, account being taken of both incident and backscattered radiations. In the present study evaluation has been made of the variation in irradiation conditions for simultaneous irradiation of multiple numbers of TLDs, examination also being made of suitable gap sizes between TLDs. For simultaneous irradiation of four TLDs, a 5 cm gap is required to ensure approximate identical irradiation conditions. Approximate identical irradiation conditions have not been found possible when making simultaneous irradation of nine TLDs.     

变量优选补正算法的鲜枣可溶性固形物检测模型传递方法研究

在水果的品质检测和分级分选中,存在不同仪器所建检测模型难以共享的难题。为此,以壶瓶枣为研究对象,利用可见/近红外光谱技术探讨仪器间可溶性固形物含量（SSC）检测模型的传递方法。首先,采用美国ASD（Analytical Spectral Device）公司生产的两台仪器采集样本的光谱信息,采用最小二乘支持向量机（LS-SVM）建立原始光谱、Savitzky-Golay一阶导数处理、标准正态变量变换后的SSC检测模型,预测不同仪器采集的光谱时3种方法的预测能力均较差。预测同一台仪器的光谱时,基于原始光谱的主仪器所建模型最优,预测集的决定系数（R2_p）和均方根误差（RMSEP）分别为0.73和1.36%。在此基础上,采用Kennard/Stone算法选取标样,利用专利算法（Shenk’s）、直接标准化（DS）、斜率/偏差算法（S/B）进行模型传递。然后,根据回归系数提取主仪器（24个）和从仪器（28个）的特征波长,优选出单一变量（SV）24个、共性变量（CV）23个、融合变量（FV）29个,均涵盖了SSC的主要吸收谱带。利用优选的变量分别建立主仪器的LS-SVM检测模型,采用主仪器的预测结果（R2_p=0.78~0.80,RMSEP=1.07%~1.13%）明显好于全波段所建模型,但预测从仪器时RMSEP为6.62%~7.88%,模型失效。最后,基于波长位置偏移和分子振动的吸收特性提出了共性变量优选结合差值补正（CV-MC）、单一变量优选结合差值补正、融合变量优选结合差值补正、共性变量优选结合波长补正算法（CV-WC）进行模型传递,并与SV-Shenk’s,CV-Shenk’s,FV-Shenk’s,SV-DS,CV-DS,FV-DS,SV-S/B,CV-S/B和FV-S/B进行对比分析。结果表明,基于全波段进行模型传递时,预测结果均较差（R2_p=0.03~0.34,RMSEP=2.44%~4.67%）;基于优选变量所建模型经SV-Shenk’s,CV-Shenk’s,FV-Shenk’s传递后的结果较差,经其他算法传递后的结果（R2_p=0.47~0.73,RMSEP=1.30%~1.90%）好于全波段;基于共性变量传递后的结果好于单一变量和融合变量,CV-MC结果最佳（R2_p=0.73,RMSEP=1.30%）,CV-WC传递后的预测结果（RMSEP=1.62%）与CV-DS和CV-S/B相近。研究表明,CV-MC和CV-WC均是一种有效模型传递算法,对建立不同仪器间通用的鲜枣品质检测模型具有重要意义。     

Investigation of the specific mass flow rate distribution in pipes supplied with a pulsating flow

A pulsating flow is typical of inlet and exhaust pipes of internal combustion engines and piston compressors. Unsteady flow phenomena are especially important in the case of turbocharged engines, because dynamic effects occurring in the exhaust pipe can affect turbine operation conditions and performance.One of the basic parameters describing the unsteady flow is a transient mass flow rate related to the instantaneous flow velocity, which is usually measured by means of hot-wire anemometers. For the flowing gas, it is more appropriate to analyze the specific mass flow rate φ_m = ρv, which takes into account also variations in the gas density. In order to minimize the volume occupied by measuring devices in the control section, special double-wire sensors for the specific mass flow rate (CTA) and temperature (CCT) measurement were applied. The article describes procedures of their calibration and measurement. Different forms of calibration curves are analyzed as well in order to match the approximation function to calibration points. Special attention is paid to dynamic phenomena related to the resonance occurring in a pipe for characteristic frequencies depending on the pipe length. One of these phenomena is a reverse flow, which makes it difficult to interpret properly the recorded CTA signal. Procedures of signal correction are described in detail. To verify the measurements, a flow field investigation was carried out by displacing probes radially and determining the profiles of the specific mass flow rate under the conditions of a steady and pulsating flow. The presence and general features of a reverse flow, which was identified experimentally, were confirmed by 1-D unsteady flow calculations.