Rotational bands in 181Ta

High-spin states in ¹⁸¹Ta have been studied via the ¹⁷⁶Yb(¹¹B,α2n) reaction at 52 MeV using the PEX array and at 57 MeV using the NORDBALL array, with α-particle detection. The previously known, K^π=(7/2)⁺ ground state band and K^π=(9/2)⁻ band have been extended to spins (29/2)⁺ and (31/2)⁻, respectively. Two new one-quasiparticle bands, the K^π=(5/2)⁺ band built on the known (5/2)⁺ isomer and a K^π=((1/2)⁻) band have been observed. Two other rotational bands with three-quasiparticle structure, K^π=(15/2)⁻ and ((19/2)⁺ with π(7/2)[404]ν²(1/2)[510](9/2)[624] and π(9/2)[514]ν²(1/2)[510](9/2)[624] configurations, respectively, have been newly observed. The half-life of the K^π=((19/2)⁺) bandhead which decays to the head of the (15/2)⁻ band has been measured to be 140(36) ns. However, transitions from the ((19/2)⁺) state to the (15/2)⁻ band have not been observed. Received: 26 August 1998     

Rotational Motion of a Solute Molecule in a Highly Viscous Liquid Studied byC NMR: 1,3-Dibromoadamantane in Polymeric Chlorotrifluoroethene

The viscosity-dependent retarding effect of a polymeric solvent on the rotation of small solute molecules is investigated by¹³C NMR relaxation measurements. It is found that the relaxation data of 1,3-dibromoadamantane in highly viscous polymeric chlorotrifluoroethene can be explained neither by isotropic nor by realistic anisotropic tumbling in a single environment. The experimental data are rationalized in terms of fast exchange between at least two environments with correlation times differing by up to two orders of magnitude. The study shows that a uniform retardation of molecular tumbling by a polymeric solvent, desirable for shifting the NMR observation window in studies of intramolecular mobility, is not always feasible.     

Wavelet and harmonic filtering for distortion-invariant volume holographic correlation

The wavelet and harmonic filtering method suggested by Zalevsky and Ouzieli is introduced in this paper and adopted in our volume holographic image recognition system. This composite filter combines several scaled versions of the cascaded wavelet and harmonic filter, obtaining high discrimination ability and wide dynamic range of rotation and scale deformations. Optical experiments are conducted to demonstrate the validity and practicability of the algorithm. To the best of our knowledge, this is the first report of using this algorithm in a volume holographic system. Moreover, the separate correlation approach proposed in this paper greatly simplifies the manufacturing process and reduces the cost of the system.     

Evolution of shapes in 59Cu

High-spin states in ⁵⁹Cu were populated using the fusion-evaporation reaction ²⁸Si + ⁴⁰Ca at a beam energy of 122 MeV. The Gammasphere Ge-detector array in conjunction with the 4π charged-particle detector array Microball allowed for the detection of γ-rays in coincidence with evaporated light particles. The resulting extensive high-spin decay scheme of ⁵⁹Cu is presented, which comprises more than 320 γ-ray transitions connecting about 150 excited states. Their spins and parities have been assigned via directional correlations of γ-rays emitted from oriented states. Average quadrupole moments of rotational bands have been determined from the analysis of residual Doppler shifts. Shell model calculations in the fp shell are invoked to study some of the low-spin states, while the experimental characteristics of the rotational bands are analyzed in the configuration-dependent cranked Nilsson-Strutinsky (CNS) approach. Received: 15 February 2002 / Accepted: 23 April 2002     

湍流燃烧二阶矩模型的大涡模拟验证

对美国Sandia国家实验室测量的甲烷-空气湍流射流火焰进行了三维大涡模拟(LES),其统计的时均量以及脉动量符合实验测量值,且和RANS代数二阶矩湍流燃烧模型模拟结果大致符合。LES统计得到的化学反应率系数脉动和甲烷浓度脉动的互关联与对应的时均量梯度的乘积分布趋势相同,大小幅值的位置也相对应,与二阶矩湍流燃烧模型的封闭假设相符,验证了二阶矩代数燃烧模型的合理性。     

利用低能质子束产生高强度放射性束流

加拿大TRIUMF实验室利用¹¹C成功验证了一种产生高强度(～10⁸ions/s)放射性束流的方法. 该方法不同于普通在线同位素分离方法, 它利用了13MeV的低能强流质子束, 可以产生一系列核天体物理实验感兴趣的高强度放射性束流.     

Study of fiber optic sugar sensor

Over the last two decades, the fiber optic technology has passed through many analytical stages. Some commercially available fiber optic sensors, though in a small way, are being used for automation in mechanical and industrial environments. They are also used for instrumentation and controls. In the present work, an intensity-modulated intrinsic fiber optic sugar sensor is presented. This type of sensor, with slight modification, can be used for on-line determination of the concentration of sugar content in sugarcane juice in sugar industry. In the present set-up, a plastic fiber made of polymethylmethacrylate is used. A portion of the cladding (1 cm, 2 cm, 3 cm) at the mid-point along the length of the fiber is removed. This portion is immersed in sugar solution of known concentration and refractive index. At one end of the fiber an 850 nm source is used and at the other end a power meter is connected. By varying the concentration of sugar solution, the output power is noted. These studies are made due to the change in refractive index of the fluid. The device was found to be very sensitive which is free from EMI and shock hazards, stable and repeatable and they can be remotely interfaced with a computer to give on-line measurements and thus become useful for application in sugar industries.     

部分子相互作用与(S_(NN))~(1/2)=130GeV Au-Au碰撞中两粒子的横向动量关联(英文)

采用蒙特卡罗模型AMPT 究了(S_(NN))~(1/2)=130GeV Au Au碰撞中部分子相互作用对两粒子横向动量关联的影响,结果表明部分子相互作用对两粒子的横向动量关联有重要的贡献．还计算了AMPT模型中(S_(NN))~(1/2)=130GeV Au Au碰撞的两粒子横向动量关联与碰撞对心性的依赖关系并与来自STAR的实验数据进行了比较,发现AMPT的理论预言很好地符合实验数据．     

A complete active-space self-consistent-field study on cubic N8

Summary Complete Active-Space Self-Consistent-Field (CAS-SCF) calculations for cubic N₈ are presented. We studied the N₈↔4N₂ reaction inD _4h symmetry and found its energy release and activation barrier with three different atomic basis sets. The energy release for this reaction is predicted to be around 526 kcal/mol, while the energy barrier to dissociation is estimated about 159 kcal/mol. These results are in substantial agreement with previousab initio estimates. The authors of this paper have agreed to not receive the proofs for correction.     

韧性金属裂纹尖端损伤区内应变场测量——数字散斑相关法应用

本文用数字散斑相关方法测量了五种不同幂硬化指数韧性金属材料(铝和铜),双边裂纹尖端细观区域内应变场.对所得结果用韧性损伤模型进行了分析.在此法中以金属自然表面结构为散斑场,不同加载状态的散斑场进行比较,得到相对变形与应变.图象之间相关性 C 是变形参数或是位移及其导数的泛函.使其相关性 C 取最大值的试凑变形即为其真实变形场.这一方法在细观测量中应用得到满意的结果.