1—50eV电子与CO2散射总截面的绝对测量

文章介绍了用飞行时间谱仪测量１－５０ｅＶ能区的ｅ－ＣＯ２散射总面值及其误差，同时将其与已有的实验结果进行比较。     

He原子电离能谱和He的1s电子动量谱测量

介绍利用作者最近研制成功的先进的多功能（ｅ，２ｅ）电子动量谱仪实验装置测量得到的Ｈｅ原子电离能谱和Ｈｅ的１ｓ电子动量谱实验结果。     

低能电子与氩原子散射总截面的绝对测量

利用电子散射飞行时间谱仪，测量了１—５０ｅＶ能量范围的电子与氩原子散射绝对总截面（ＴＣＳ），测量精度达到５％。实验结果与同类实验和近期的理论结果进行了比较，在实验误差范围内符合得较好。     

一套研究重离子—原子碰撞过程中小角度散射的散射粒子—反…

本报导通过测量离子－原子碰撞过程中反冲离子横向动量的方法获得散射角θ≤１０＾－＾４ｒａｄ的单重和多重电离截面，即散射粒子－反冲离子飞行时间谱仪系统。中将介绍建于兰州大学２×１．７ＭＶ串列加速器上的散射粒子－反冲离子飞行间谱仪系统的机械设计，性能参数，数据获取，电子学框图以及利用１ＭｅＶ质子轰击氩气时测量反冲氩离子飞行时间谱的试运行实验及结果。     

缪轻子反常磁矩和北京谱仪实验

最新的缪子反常磁矩实验测量结果与标准模型理论预言偏离4.2σ,提供了新物理存在的重要证据.然而要确认新物理的存在,实验和理论还需要进一步提高精度.运行在量子色动力学微扰与非微扰过渡能区的北京谱仪实验能够约束缪子反常磁矩理论计算中最重要的误差来源——强相互作用的修正.文章介绍了缪子反常磁矩的实验与理论现状,特别是北京谱仪...     

一套研究重离子—原子碰撞过程中小角度散射的散射粒子—反冲离子飞行时间谱仪系统

本文报导通过测量离子—原子碰撞过程中反冲离子横向动量的方法获得散射角θ≤10~(-4)rad的单重和多重电离截面,即散射粒子—反冲离子飞行时间谱仪系统。文中将介绍建于兰州大学2×1.7MV串列加速器上的散射粒子—反冲离子飞行时间谱仪系统的机械设计,性能参数,数据获取,电子学框图以及利用1MeV质子轰击氩气时测量反冲氩离子飞行时间谱的试运行实验及结果。     

在HL－1M装置上用弯晶谱仪测量离子温度

本文叙述在ＨＬ－１Ｍ装置上用弯晶谱仪获取Ｆｅ的类Ｈｅ离子谱，用谱线的多谱勒加宽测量等离子体的离子温度，得到的等离子体ＨＬ－１Ｍ装置离子温度为５００—８００ｅＶ。     

~（56，57）Fe，~（59）Co（α，d）核反应及拉长态性质的实验研究

利用△Ｅ—Ｅ望远镜及Ｑ３Ｄ磁谱仪，在ＨＩ－１３串列加速器提供的３５ＭｅＶα离子束轰击下，测量５６，５７Ｆｅ，５９Ｃｏ（α，ｄ）５８、５９Ｃｏ，６１Ｎｉ核反应的精细能谱和微分截面角分布，微观ＤＷＢＡ近似用来分析实验数据．在５６Ｆｅ（α，ｄ）５８Ｃｏ核反应观测的９个强激发能级中，重点分析和讨论了６．７９ＭｅＶ和６．４ＭｅＶ能级的性质，观测到迄今所能看到的最高拉长组态（１ｇ９／２，１ｇ９／２）９和首次确认了６．４ＭｅＶ能级Ｊπ＝１＋．在５７Ｆｅ，５９Ｃｏ（α，ｄ）核反应测量中，未看到孤立强激发能级，它意味着强度分散在许多能级上，以致看不到孤立拉长态存在的实验证据．     

铝靶三倍频激光烧蚀参数实验研究

叙述了采用时间空间积分晶体谱仪和时间分辨晶体谱仪等探测器测量铝平面靶强激光烧蚀参数的方法，给出了三倍频强激光烧蚀铝平面靶的质量烧蚀速率和烧蚀压。实验结果与收集到的国外数据进行了比较，它们在误差范围内一致。     

透射式柱面弯晶谱仪的单滤片能量刻度方法

根据布拉格衍射定律和晶层模型,推导了透射式柱面弯晶谱仪的三维衍射光路的理论公式,并利用该理论研究了谱仪测量光谱的能量刻度问题。在考虑了实验中谱仪与光源的准直度和记录介质放置姿态带来的误差后,发现利用多种滤片的K吸收边进行公式拟合得到弯晶谱仪能量刻度曲线的方法对低能X射线谱线的误差较大,进而提出了用单滤片通过理论公式模拟计算进行谱仪能量刻度的方法。通过对透射式柱面弯晶谱仪测量到的Ag靶X光机的实验光谱进行能量刻度,实现了用单滤片在线定标弯晶谱仪,验证了理论公式和能量刻度方法的正确性。     

The measurement of energy spectra of neutral particles in low energy ion scattering

An apparatus is described for low energy (0.1–10 keV) ion scattering (LEIS) experiments. A time of flight (TOF) spectrometer is incorporated in the system to be able to measure the energy of particles in the neutral state after scattering. The energy resolution ΔE/E of the TOF spectrometer is discussed and found to be 0.5% (FWHM). This is sufficient for our scattering experiments. An electrostatic analyzer (ESA) is used to measure the energy of scattered ions [ΔE/E=0.5% (FWHM)]. Experiments show that in general the ion dose needed to obtain a TOF spectrum (2×10¹⁰ ions/cm²) is much smaller than the dose needed for an ESA-spectrum (6×10¹³ ions/cm²). The ion spectra measured with the TOF spectrometer, by subtracting the neutral yield from the total yield, as well as with the ESA are found to agree quite well. This provides a way to calibrate the TOF spectrometer. The determination of the ion fraction of scattered particles is discussed [10 keV⁴⁰Ar⁺ on Cu(100), scattering angle 30°]. It is shown that the TOF spectrometer is able to measure light recoil particles (e.g. hydrogen) from a heavy substrate. In the analysing system is, in addition to the TOF spectrometer, also incorporated a stripping cell to measure the energy of neutral scattered particles. An energy spectrum of neutral scattered particles measured with both methods is shown.     

用直接中子法测量（n, 2n）反应截面的实验方法研究

在中国原子能科学研究院HI-13 串列加速器上的非常规多探测器快中子飞行时间谱仪上,采用直接中子法测量了14.3 MeV 中子与169Tm作用的(n,2n) 反应截面。用蒙特卡罗方法模拟了次级中子的产生,以对实验数据进行中子注量率衰减、多次散射和有限几何修正,同时结合SUNF 方法得到的评价能谱,给出了(n,2n) 反应截面的实验测量结果。测量截面以中子弹性散射微分截面作为标准截面来归一,并用反冲质子望远镜测量n-p 反应的反冲质子,以监视中子注量率。用直接中子法测量得到的结果与评价数据进行了比较,讨论了采用这种方法测量(n,2n) 反应截面的可行性。(n,2n) reaction cross section from 169Tm at 14.3 MeV was measured with the direct emittedneutron coincidence detecting method, using abnormal fast neutron TOF spectrometer on the HI-13 Tandem Accelerator at CIAE. Monte-Carlo method was used to simulate the generation of secondary neutron and correct the experimental data considering neutron flux attenuation, multiple scattering and finite geometry correction. Combining with evaluated spectra given by SUNF program, the experimental measurement results of the (n,2n) reaction cross sections were given. Cross sections of measurements were normalized by using neutron elastic scattering differential cross section as a standard section, and a recoil proton telescope was used to measure recoiling proton from the n-p reaction to monitor neutron flux rate. After comparing the experimental results with evaluated data, the feasibility of the direct emitted-neutron coincidence detecting method is discussed.     

Measurement of Small-Angle Scattering of 14.7MeV Neutrons by C and Be Nuclei

The 14.7MeV neutron small-angle elastic scattering differential cross sections of C and Be are measured by a position-sensitive spectrometer with associated particle time-of-flight method.The corrections for neutron flux attenuation and multiple scattering are performed by using Monte-Carlo calculations.The experimental results are compared with the opticalmode calculation and other measurements.     

8.19 MeV中子与9Be作用的次级中子双微分截面测量

用中国原子能科学研究院HI13串列加速器上的多探测器快中子飞行时间谱仪, 测量了8.19 MeV中子与9Be作用时, 从20°到160°区间26个角度的次级中子双微分截面。测量截面以np散射截面作为标准进行归一。实验结果用Monte Carlo方法进行了中子注量率衰减、多次散射和有限几何修正, 并用MCNP4C程序对所用的Monte Carlo程序进行了验证。测量结果与评价数据以及其它实验室的数据进行了比较。The secondary neutron emission double differential cross section of 9Be induced by 8.19 MeV neutron was measured at 26 different angles from 20°to 150°by using the multi detector fast neutron TOF spectrometer at the HI 13 Tandem Accelerator at China Institute of Atomic Energy(CIAE). The results were normalized to np scattering measurement. A special Monte Carlo code which was validated with the MCNP 4C code was employed to analyze the measured data for the corrections of neutron flux attenuation, multiple scattering and finite geometry. The measured results were compared with the evaluated data and the other measurements.      

飞行时间质谱峰值的漂移

飞行时间质谱仪(time-of-flight mass spectrometer, TOF-MS)在分子团簇的激光电离/解离动力学研究中广泛使用。文章报道了在用脉冲355 nm的YAG激光进行水/甲醇二元团簇的多光子电离研究中,发现在电离激光相对于脉冲分子束的不同延时下,即激光作用于脉冲束的不同位置,飞行时间质谱仪测得的离子的质谱峰值发生漂移。在激光作用于脉冲束的中段时,离子的信号最强,同时离子的峰值漂移达到最大。分析认为：这种峰值漂移不是因为新质量数谱峰的出现,而是离子在穿越质谱仪的离子引出区和加速区极板时发生部分离子吸附,引起极板间电压的起伏造成的。离子在电场起伏下的数值模拟与实验中观测到的离子峰值漂移规律一致。     

Low-energy neon-ion scattering and neutralization on first and second layers of a Ni(001) surface

The scattering and neutralization of 2.4 and 5 keV Ne⁺ ions on the Ni(001) surface have been studied by time-of-flight (TOF) and electrostatic analyzer (ESA) techniques. The scattering yield of neutrals plus ions (by TOF) is strongly dependent on crystal orientation, in one direction being reduced by the shadowing of 2nd layer atoms by 1st layer atoms, or in another being increased by focussing of ions onto the 2nd layer by 1st layer atoms. Ion yields (by ESA) show little of this variation since the ions are largely neutralized on scattering from the second layer. The results thus demonstrate and explain the first layer selectivity of low-energy ion scattering by ESA for a case in which there is no shadowing of second layer atoms by the first layer. On the other hand, the ability to measure and distinguish first and second layer scattering of neutrals and ions by TOF suggests the possibility of composition analysis of individual layers of single crystal alloys and compound semiconductors.     

A method to enhance coincidence time resolution with applications for medical imaging systems (TOF/PET)

A coincidence timing spectrometer was assembled using NaI(Tl) inorganic and BC418 type organic (plastic) scintillation detectors. The constant fraction timing method was used. Coincidence time resolution values of the detectors, which have great importance in TOF/PET measurements, were obtained separately. The resolutions were enhanced using a different method in a start-stop coincidence spectrometer: the signals from the start detectors were delayed. The results from the FLUKA Monte Carlo simulation code agreed well with the experimental results.     

High-intensity laser induced ion acceleration from heavy-water droplets

Fusion neutrons from a heavy water droplet target irradiated with laser pulses of 3 x 10(19) W/cm(2) and from a deuterated secondary target are observed by a time-of-flight (TOF) neutron spectrometer. The observed TOF spectrum can be explained by fusion of deuterium ions simultaneously originating from two different sources: ion acceleration in the laser focus by ponderomotively induced charge separation and target-normal sheath acceleration off the target rear surface. The experimental findings agree well with 3D particle-in-cell simulations.     

15N（p,n)15O反应中子源0°角激发函数测量

利用中国原子能科学研究院HI-13串列加速器上的多探测器快中子飞行时间谱仪, 测量了38个不同入射质子能量点下15N（p, n)15O反应0°角方向的激发函数。 测量数据用蒙特卡罗方法进行了模拟, 以进行中子注量衰减和入射窗厚度的不确定度修正。 实验在入射质子能量位于6.029—8.056 MeV之间时发现了3个共振峰, 这一点与DROSG 2000评价数据及PTB数据相符合, 但三家的截面数值存在差异, 对这些差异需要作进一步深入探讨。 The excitation function of 15N（p, n)15O reaction at 0 degree was measured at 38 energy points using the fast neutron Time of Flight (TOF) spectrometer at the HI 13 Tandem Accelerator in the China Institute of Atomic Energy（CIAE）. The measured data were analyzed by Monte Carlo simulation for the corrections of neutron flux attenuation and uncertainty of the thickness of the entrance foil. Three resonance peaks were observed in this experiment in the energy range from 6.029 to 8.056 MeV,which is comparable with the DROSG 2000 evaluated data and the PTB data. However,more experimental studies are needed since the cross sections deviate with each other.     

Simultaneous energy analysis in a large angular range: A novel neutron spectrometer,its resolution and applications

A new type of crystal spectrometer for elastic and inelastic neutron scattering has been set up by modifying an existing flat-cone diffractormeter at the BER II-reactor in Berlin (West). The main difference to conventional triple axis spectrometers is the analyser part. It consists of large crystal plates which reflect the neutrons out of the horizontal plane into a curved multicounter. This allows simultaneous measurements in a large and continuous range of scattering angles for a constant energy transfer. The resolution function has been calculated and compared with experimental results. There is the possibility to focus acoustical phonons. We present applications together with experimental results such as quasielastic diffuse scattering in orientationally disordered crystals and inelastic scattering due to acoustical phonons. In combination with the flat-cone technique all elastic and inelastic scattering events of a single crystal can be collected in a systematic and efficient way.in collaboration with the Hahn-Meitner Institut, Berlin (West)