共查询到18条相似文献,搜索用时 211 毫秒
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为了对电子俘获核素活度进行绝对测量,我们研制成高气压正比计数器装置。当正比计数器对电子的探测效率达到1和计数管内工作气体压力足够高时,粒子的能量全部损耗在计数管灵敏体积内,因此,可以把该正比计数器当作谱仪使用.与液体闪烁谱仪相比较,它具有较高的能量分辨率。 相似文献
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使用内充气正比计数管测量放射性气体活度是放射性气体活度绝对测量的最主要方法之一.基于Geant4(GEometry ANd Tracking 4)的模拟数据,研究了内充气正比计数法测量活度的过程中,壁效应和小脉冲幅度的修正方法本身对最终活度测量的不确定度的影响.根据模拟结果,得到如下结论:为达到0.3%以下的不确定度,3H与85Kr的测量下阈应分别低于0.2 keV和0.6 keV;壁效应对3H的影响较小,对85Kr的影响较大,但其结果可通过改变气体压强的方法修正到0.3%以内的不确定度. 相似文献
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基于大面积无窗流气正比计数器和多道能谱测量单元,建立了2πα、2πβ粒子发射率现场校准装置。性能测试结果表明:该装置对α平面源的坪区为700~1 500 V,坪长为800 V,坪斜为0.25%/100 V;对β平面源的坪区为1 650~2 050 V,坪长为400 V,坪斜为0.44%/100 V。使用该装置测量2πα、2πβ粒子发射率基准装置定值的标准平面源,经各项修正后,结果与基准测量结果在不确定度范围内一致。在现场校准了一批α、β标准平面源,校准结果与上一校准周期的结果在不确定度范围内一致,验证了该装置作为现场测量标准装置实现粒子发射率量值现场传递的可行性。 相似文献
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等离子体破裂防护快速充气阀性能研究 总被引:1,自引:0,他引:1
托卡马克装置在放电过程中经常会发生破裂现象.破裂会对装置造成很大的危害.为了满足在实验先进超导托卡马克(EAST)装置上开展高压气体注入来缓解等离子体破裂研究的需求,基于涡流驱动的等离子体破裂防护快速充气阀已经在中科院等离子体物理研究所研制成功,该阀的成功研制为在EAST上面开展高压气体注入来缓解等离子体破裂研究提供了有效的工具.为了更加精确地测量快阀的响应时间并对其流量进行标定,搭建了基于磁栅尺的测试平台来测量快阀的响应时间,并编写了相应的测试程序,测试结果表明快阀得到触发信号后在0.5ms时间内就可以开启,其流量可以从0~70000PaL之间方便进行调节,其响应时间及流量完全可以满足等离子体破裂防护对充气系统的要求. 相似文献
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目前普遍采用称量法制备标准气体,在此过程中气瓶体积膨胀所引入的空气浮力的不确定度贡献不可忽视。设计了一个气瓶充气膨胀率测量装置,该装置可以控制气瓶内充入气体的压力,并利用精密移液管测量气瓶体积的膨胀量,从而准确计算出气瓶的充气膨胀率。利用该装置对国内常见的2L、4L和8L铝合金气瓶进行了测量,结果显示气瓶体积的膨胀与充入气体的压力近似成线性正相关。而且气瓶外观体积越大,充气膨胀率的数值越大,量值之间也呈现出较强的相关性。基于获得的气瓶充气膨胀率数据,可以进一步降低气瓶体积膨胀对瓶内充入气体质量的不确定度贡献,从而使气体质量的计算更加精确。 相似文献
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为了研究工作气体气压变化对α和β源表面发射率绝对测量的影响,在α、β表面粒子发射率基准装置上,通过改变多丝正比计数器工作气体压强,对大面积α平面源241Am、β平面源204Tl和90Sr/90Y的表面粒子发射率进行了绝对测量,并通过阈值外推方法对低能信号引起的漏计数率进行修正。结果表明,当工作气体压强在50~180kPa气压范围内变化时,不同气压条件下的α、β表面粒子发射率测量结果在实验不确定度范围内相一致。基于Geant4程序包对探测器结构进行建模,Monte Carlo方法给出的模拟结果得出的结论与实验结果相符。 相似文献
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基于大面积流气正比计数器建立了2πα、2πβ粒子发射率测量系统。对该系统进行了性能测试,结果表明其对α平面源的坪长为600~800V,最优平均坪斜为0.2%/100V;对β平面源的坪长为350~400V,最优平均坪斜为0.23%/100V;用点状~(239)Puα源测得100mm×150mm中心区域的计数均匀性为0.45%。通过对粒子发射率测量结果进行本底、死时间、甄别阈修正,实现了α、β平面源的2π粒子发射率绝对测量,其中对α源发射率测量结果的扩展不确定度优于0.9%(k=2),对β源发射率测量结果的扩展不确定度优于1.1%(k=2)。与2πα、2πβ粒子发射率基准比对测量了~(233)U、~(241)Am等9枚进口的α、β标准平面源,测量结果均在不确定度范围内一致。 相似文献
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Chau Q Lahaye T Ménard S Donadille L Bolognese T Rannou A 《Radiation protection dosimetry》2004,110(1-4):297-300
Tissue-equivalent proportional counters (TEPC) allow the measurements of the absorbed dose and the ambient dose equivalent for neutron fields. A device based on this approach, called NAUSICAA((1,2)), has already been developed by IRSN to be used in high energy neutron fields for space applications. The response of this detector underestimates significantly the dose equivalent at low energies (several hundred keV) which represent the major component of neutron fields at workplaces in the nuclear industry. A counter with a similar geometry (cylindrical detector) and a lower gas pressure was studied in order to simulate a 1 microm biological site. In 2003, the performance of the device was further improved by adding a small amount of 3He to the tissue-equivalent gas (propane based) in order to increase the response for the lower energies of neutrons. Three amplification circuits were used to cover lineal energy range from 10(-1) to 10(4) keV microm(-1). Tests were performed in monoenergetic neutron and source fields. This paper presents the experimental results obtained with this change. 相似文献
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Hiroshi Miyahara Masatoshi Watanabe Tamaki Watanabe 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,241(1):186-190
We have measured gas amplification factors in three types of coaxial proportional counters for a 90% argon: 10% methane mixture (0.1–1.6 MPa) and a methane gas (0.1–0.5 MPa). The results showed that the formula by Diethorn or Williams and Sara was inadequate for the expression of gas amplification but that the Zastawny and Charles formulas could give a good fit for the given counter conditions. New values for constants of these formulas were determined from the experiments. 相似文献
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《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1986,251(1):156-159
We have measured gas amplification factors in counters with rectangular cross section for a 90% argon 10% methane mixture (0.1–1.6 MPa) and methane gas (0.1–0.6 MPa). In the theoretical calculation, an effective cathode radius was introduced from Tomitani's treatment that the potential distribution near the the anode calculated by means of a conformal transformation of the Jacobian elliptic function coincided with that of a cylindrical counter. The experimental results showed that the formulas of Zastawny and of Charles could give a good fit for given counter conditions; therefore, the effective cathode radius for a counter with rectangular cross section is available in the calculation of the gas amplification factor. 相似文献
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A 12 mm tissue-equivalent proportional counter (TEPC) was designed, constructed and successfully tested. This detector achieves features common to others TEPCs, but it does not use field shaping electrodes and it is able to work at higher bias voltages which makes it capable of measuring the whole range of energy deposition events for gamma rays. The following approach was used to design the detector: first of all the use of a cylindrical shape detector featured as simple as possible but keeping its performance as well, the next point is to avoid the use of field shaping tubes and the last one is to make the preamplifier small and as close as possible to the detector. Its construction is based on a cylindrical proportional counter with A-150 tissue-equivalent material as cathode, TE-methane gas as a proportional gas and a 20 microns diameter wire as anode. 相似文献
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本文介绍了液化石油气加气机容积式计量标准装置的基本原理、结构和使用方法 ,并对其测量不确定度进行了评定。结果表明 :本装置设计原理正确、使用方便、测量准确度较高 ,适宜推广使用。 相似文献