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标样(CRM)在分析化学中的重要性已为大家所认识。仅西方世界,各种标样的生产单位就至少有130家。如果只考虑组成标样(如矿石、岩石和合金等),至少有39家生产单位,它们共提供约250种矿石、精矿、岩石、土壤和水泥标样及2400多种合金标样。标样广泛用于分析数据的质量控制——直接校准方法和仪器;检验“控制分析方法”的精密度、准确度和灵敏度;开拓和评定新方法或 相似文献
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应用热释光技术对模拟阳光晒退后的泥石流标样和实际阳光晒退后的泥石流样品进行了热释光信号分层测定。实验结果表明:泥石流发生后经过曝光,样品积存热释光晒退程度随深度增加逐渐减弱,光晒退明显。光晒退随光照强度和时间增大而增强,深度增大,但深度变化总体不大。模拟的阳光晒退实验晒退深度达1 mm左右,实际阳光晒退实验晒退深度达6 mm左右。根据等效剂量随深度的变化可知,天然泥石流块状样由两次泥石流堆积形成。这一结果可为利用热释光技术开展泥石流测年和发生期次研究提供依据。 相似文献
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按照国家一级标准的规范,制作了核磁共振(NMR)岩心实验分析的系列化标准样品一流体标样、离散体系标样和固体陶瓷标样,通过对这些标样以及天然岩心的实验考察,将其应用于大庆、新疆、大港等油田的NMR岩心实验分析。结果表明,由于流体标样、固体陶瓷标样和天然岩心的弛豫机理不同,其对岩心NMR孔隙度的标定效果不同。流体标样适合于贝瑞砂岩、陆相沉积分选好、泥质含量低的砂岩NMR孔隙度的标定;固体陶瓷标样适合于分选中等的泥质砂岩NMR孔隙度的标定;对粘土含量高的砂岩、含顺磁性物质的砂岩和砾岩等复杂岩性岩样,用流体标样和固体陶瓷标样标定都得不到准确的NMR孔隙度值。为此,建议选用本地区有代表性的天然岩心作为标样标定其孔隙度,或者研究该类岩石内部磁场梯度分布,得到经内部磁场梯度校正后的NMR孔隙度。 相似文献
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本文叙述了一个“非剂量”热释光断代方法。在这个方法中,总热释光和年热释光分别用考古样品中的天然矿物和人造热释光材料测定,并用热释光直接估算年龄。用本方法测定了28个考古样品,结果表明,这些年龄与用剂量法测得的热释光年龄一致,并具有误差降低和不需要刻度放射源的优点。 相似文献
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用纯仪器中子活化分析法测定吉林地球化学水系沉积物Ⅱ级标样GRD30~46,是在我室测定我国首批地球化学标样系列GSD1~8时所制定的技术方法的基础上进行的。对吉林标样GRD30~46共测得21种元素。 吉林标样共照射3次,每次照射标样均制成双份,目的在于从中检验标样的平行性。此标样的标准用美国地调所的GXR,测得的γ能谱由PDP-11/04型计算机按Spectran-F分析软件包给出分析结果,再由我室自编的 相似文献
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本文简要讨论了光子外照射事故后,剂量测量的重要性及各种物理剂量测量方法和它的实用性,其中包括热释光和电子自旋共振方法。对其它物理剂量测量技术也作了扼要的介绍。 相似文献
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为确定实验室对环境样品中90Sr的检测能力,保证检测结果准确可靠,需经常性地开展实验室内外部质量控制。本文针对90Sr分析中原有的质量控制与评价方法的不足,通过对质控图评价法、En值法、Z比分数法和临界值法的详细研究,结合实例对环境样品90Sr检测过程的内外部质量控制与评价方法进行了较为系统的探讨。对于内部质量控制和评价方法:空白样品可采用质控图和判断限评价;平行双样可采用临界值法评价;掺标盲样和放化回收率检验均可采用En值法评价;人员间比对可采用临界值法、En值法、Z比分数法和t检验法。对于外部质量控制和评价方法:测量审核可采用临界值法、En值法和Z比分数法;能力验证可采用En值法和Z比分数法。 相似文献
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超微弱发光分析法在辐照糖类食品中鉴别检测的应用 总被引:2,自引:0,他引:2
糖是大多数食品的重要组成部分。本工作应用超微弱发光分析技术,研究三种糖分在辐照前后变化过程,以建立一种无需对照样品的辐照食品鉴别检测新方法。研究结果表明,食品经不同剂量^60Coγ射线辐照处理后,在干燥状态下,辐照后葡萄糖和蔗糖样品的超微弱发光强度变化不大。但是,在测量过程中瞬间加水溶液后,样品的超微弱发光强度会产生显著变化,其发光峰所对应的光子数与辐照剂量密切相关。根据这一特有的变化规律, 相似文献
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《核技术(英文版)》2015,(4)
In order to do alignment between the timing signal and the synchrotron X-ray pulse on the sample spot in the time domain,measuring time structure of the storage ring on the sample spot inside the experimental hutch is a foundational step during the time-resolved experiments using the pulsed synchrotron X-rays with the time structure defined by the storage ring.In this work,the method of time-resolved X-ray excited optical luminescence(TRXEOL)was designed and implemented to do the measurement.It is based on the principle of time-correlated single photon counting techniques.The measurement system consists of a spectrometer with a detector of photomultiplier tube,a timing system,a set of nuclear instrument modules and a luminescent material of zinc oxide.The measurement was performed on the X-ray absorbed fine structure spectrum beamline at Shanghai Synchrotron Radiation Facility.The results show that this method can be used to measure the time structure of the storage ring with a precision of less than 1 ns.The measurement system can also be used for the time-resolved research for the optical luminescent materials. 相似文献
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F. D. McDaniel B. L. Doyle C. H. Seager D. S. Walsh G. Vizkelethy D. K. Brice C. Yang P. Rossi M. Nigam M. El Bouanani G. V. Ravi Prasad J. C. Schwartz L. T. Mitchell J. L. Duggan 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2002,190(1-4):1-10
A new ion beam analysis-based, single ion technique called the time to first photon has been developed to measure the decay of the luminescence signal of phosphors. Such measurements are currently needed to study luminescence decay mechanisms following high-density excitations and to identify strongly luminescent phosphor coatings with short lifetimes for ion photon emission microscopy (IPEM). The samples for this technique consist of thin phosphor layers placed or coated on the surface of PIN diodes. Single ions from an accelerator strike this sample and simultaneously create ion beam induced luminescence (IBIL) from the phosphor that is measured by a single-photon-detector, and an ion beam induced charge collection (IBICC) signal in the PIN diode. In this case, the IBICC signal provides the start pulse and the IBIL signal the stop pulse to a time to amplitude converter. It is straightforward to show that this approach also measures a signal proportional to activity versus time with an accuracy of 5% as long as the number of detected photons per ion is less than 0.1, which usually requires the use of absorbers for the IBIL detector or electronic discrimination for the IBIL signals. Details of the new analysis are given together with examples of luminescence decay measurements of several ceramic phosphors being considered to coat IPEM samples. IPEM is currently being developed at Sandia National Laboratory (SNL), the University of North Texas in Denton, and the Universities and INFN of Padova and Torino. 相似文献
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Marie Sydoff Kristina Stenström 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(7-8):924-926
The Department of Physics at Lund University is participating in a European Union project called EUMAPP (European Union Microdose AMS Partnership Programme), in which sample preparation and accelerator mass spectrometry (AMS) measurements of biological samples from microdosing studies have been made. This paper describes a simplified method of converting biological samples to solid graphite for 14C analysis with AMS. The method is based on online combustion of the samples, and reduction of CO2 in septa-sealed vials. The septa-sealed vials and disposable materials are used to eliminate sample cross-contamination. Measurements of ANU and Ox I standards show deviations of 2% and 3%, respectively, relative to reference values. This level of accuracy is sufficient for biological samples from microdosing studies. Since the method has very few handling steps from sample to graphite, the risk of failure during the sample preparation process is minimized, making the method easy to use in routine preparation of samples. 相似文献