氮-14远程核四极共振谱仪

为了满足检测与探头有一定距离的含氮化合物的核四极共振信号,本文研制了一台结构简单,造价低廉的核四极共振操测仪.它利用了脉冲付里叶变换技术,可将获得的核自由感应衰减信号或者回波信号进行相干累加.整个系统分硬件和软件两大部分.前者由射频脉冲放大器(约500W脉冲输出功率),探头,接收机,MCS-96型单片机和PC机构成.后者由单片机上的脉冲序列程序与PC机上的数值信号处理程序组成.利用这台谱仪,可以在几十秒时间内得到距离探头线圈10cm内的典型¹⁴ N样品的核四极共振谱.     

27Al NMR study in ZrNiAl

We have studied the microscopic properties of the hexagonal ZrNiAl, a model compound for a wide family of intermetallic compounds crystallizing in this type of structure, by using ²⁷Al NMR spectroscopy. We have investigated the lineshape of static and MAS NMR spectra as a function of magnetic field strength (4.7–9.4 T) and temperature (5–300 K). Our data indicate that the ²⁷Al NMR spectra result from a combined effect of quadrupole and anisotropic shift interactions. The ²⁷Al nuclei are in an environment characterized by the quadrupole coupling constant e²qQ/h of 3.3 MHz, asymmetry parameter η_Q of 0.42, isotropic shift δ_iso of 393 ppm, shift anisotropy δ_anis = δ_zz − (δ_xx + δ_yy)/2 of 150 ppm, and asymmetry factor η_S of 0.5. They are found to be temperature independent. The spin–lattice relaxation rate measured at 7.05 T is proportional to the temperature with T₁T = 135 s K. The mechanisms responsible for observed values of δ_iso, δ_anis, T₁T, and the enhanced Korringa constant are discussed.     

Lie algebraic analysis for the nonlinear transport of intense bunched beam in electrostatic quadrupoles

In this paper, the nonlinear transport of intense bunched beams in electrostatic quadrupoles is analyzed using the Lie algebraic method, and the results are briefly presented of the linear matrix approximation and the second order correction of particle trajectory in the state space. Beam having K-V distribution and Gaussian distribution approximation are respectively considered. A brief discussion is also given of the total effects of the quadrupole and the space charge forces on the evolution of the beam envelope.     

Solid state proton imaging detected by quadrupole resonance

A double resonance method for imaging of solid materials containing quadrupole nuclei via the coupled protons is reported. The technique uses a static field gradient to encode the position on the protons and the method of double resonance spin-echo to detect the occurrence of proton resonances by affecting the zero-field echo signal from the quadrupole system. The double resonance imaging method offers the advantages of higher spatial resolution and straightforward image reconstruction for powder samples compared with rotating-frame and Zeeman-perturbated nuclear quadrupole resonance encoding techniques.     

NQR炸药检测系统中激励脉冲拖尾的抑制

介绍了核四极矩共振（Nuclear Quadrupole Resonance简称NQR）炸药检测系统的基本原理及检测过程中面临的如何消除激励脉冲信号拖尾对NQR检测信号的影响问题. 文中采用了在发射电路中增加消振铃电路来消除激励脉冲拖尾的方法，并给出了电路分析和实验结果. 经实际应用验证，该种方法对消除激励脉冲拖尾具有较好的效果，提高了系统的探测能力.     

Microscopic interacting boson model calculations for even-even <Superscript>128–138</Superscript>Ce nuclei

In this study, we determined the most appropriate Hamiltonian that is needed for the present calculations of energy levels and B(E2) values of ^128–138Ce nuclei which have a mass around A≅130 using the interacting boson model (IBM). Using the best-fitted values of parameters in the Hamiltonian of the IBM-2, we have calculated energy levels and B(E2) values for a number of transitions in ^{128,130,132,134,136,138}Ce. The results were compared with the previous experimental and theoretical (PTSM model) data and it was observed that they are in good agreement. Also some predictions of this model have better accuracy than those of PTSM model. It has turned out that the interacting boson approximation (IBA) is fairly reliable for calculating spectra in the entire set of ^{128,130,132,134,136,138}Ce isotopes and the quality of the fits presented in this paper is acceptable.      

Segmented linear radiofrequency quadrupole/laser ion source project at TRIUMF

Reactions such as ²⁵Al(p,γ)²⁶Si are the key to understand the production of ^26g Al and ^26m Al in our galaxy. Experimental results could provide important constraints on nova nucleosynthesis and modelling where ²⁶Al is believed to be produced. To achieve such measurements, high-intensity and high-purity radioactive beams are required. However, production targets at ISOL-type facilities such as ISAC at TRIUMF produce high-intensity alkali beams by surface ionization on hot transfer tubes hampering the measurement of isotopes of interest. To overcome this issue, an ion source combining a segmented linear radiofrequency quadrupole (RFQ) to a laser ion source is being built. Its main function is to suppress alkali impurities whilst allowing for fast-release of short-lived isotopes. The beam production method, the RFQ/laser ion source and the removal of alkali contaminants are discussed in this paper.     

Sb-NMR/NQR study of CeIrSb

We report Sb-NMR/NQR measurements on a valence fluctuating compound CeIrSb, which is isostructural to the Kondo semiconductors CeRhSb and CeNiSn. The nuclear spin-lattice relaxation rate divided by temperature, 1/T₁T has a maximum around 300 K and considerably decreases in proportion to T² when cooling down, followed by a 1/T₁T∼const. behavior below 20 K. These results indicate that CeIrSb has a V-shaped pseudogap with a residual density of states at the Fermi level. The size of pseudogap for CeIrSb is estimated to be about 350 K, which is one order of magnitude larger than the values of 28 K for CeRhSb and 14 K for CeNiSn. The larger size of energy gap in CeIrSb may be attributed to much stronger c-f hybridization than those for CeRhSb and CeNiSn.     

A microscopic study of deformation systematics in <Superscript>154–166</Superscript>Dy isotopes

The Hartree-Bogoliubov (HB) framework of calculations has been applied for calculating various nuclear structure quantities for ^154–166Dy mass chains. In this framework, the intrinsic quadrupole moments, the low-lying yrast states (E ₂⁺ and E ₄⁺) and occupation numbers for various shell model orbits have been obtained. The calculated results indicate that the observed onset of deformation in going from ¹⁵⁴Dy to ¹⁶⁶Dy arises due to enhanced occupation of (h _11/2)_π orbit, increased polarization of (d _5/2)_π orbit and increase in the occupation of down-slopping ‘k’ components of (i _13/2)_υ and (h _9/2)_υ orbits.      

基于全二维气相色谱-四极杆飞行时间质谱高通量检测独活挥发油化学成分

利用全二维气相色谱-四极杆飞行时间质谱(GC×GC-QTOF MS)建立了一种适用于独活挥发油化学成分的高通量检测方法,样品经水蒸气蒸馏提取后,直接采用全二维气相色谱进行分离,并根据谱库匹配、保留指数及精确质量数进行定性确认.结果表明,共分离鉴定了独活挥发油中207种化学成分,其中正向、反向匹配因子大于800的化合物占...