145Er的β延发质子衰变性质研究

通过92Mo(58Ni, 2p3n)熔合蒸发反应生成了非常缺中子核145Er。利用氦喷嘴带传输系统把研究目标核传输到低本底测量站, 进行了质子 γ符合测量, 得到了不受同量异位素干扰的145Er的β延发质子谱。经过仔细分析与延发质子符合的γ谱, 发现了145Er的11/2-同核异能态具有β延发质子衰变性质。经拟合退激144Dy不同激发态γ跃迁的衰变曲线, 得出145Er的1/2+基态和11/2-同核异能态的半衰期分别为(1.6±0.6)和(0.6±0.1) s。最后, 简单介绍了中重质量区缺中子新核素的合成及衰变研究计划。The neutron deficient isotope 145Er was produced via the fusion evaporation reaction 92Mo(58Ni, 2p3n). The reaction products were transported to a low background counting area using a He jet tape transport system, and proton γ coincidence measurements were carried out. Based on the analysis of γ transitions in coincidence with β delayed protons, the β delayed proton decay of an νh11/2 isomer in 145Er was proposed. By fitting the decay curves of the γ transitions depopulating the low lying states in 144Dy, the half lives of the ground state and the νh11/2 isomeric state in 145Er were deduced to be (1.6±0.6) and (0.6±0.1) s, respectively. An experimental plan to synthesize new β delayed proton precursors in the medium heavy mass region has been presented.     

原子核基态双质子衰变的研究进展

基态双质子衰变是质子滴线区原子核的一种奇异衰变。 它可以揭示质子滴线区原子核外层质子对的结构行为, 检验现有核模型理论应用于极端条件下原子核的正确性。 搜索基态双质子衰变是人们广泛关注的一个实验难题, 直到理论预言提出后40多年才取得明显进展。 简要介绍了这一研究的进展情况。 The ground-state two-proton decay is an exotic decay beyond proton drip line. It deals with the structure behavior of the proton pair at outside orbital in a proton drip line nucleus, and can be used to check the current nuclear model under extreme condition. Experimental observation of ground state two proton decay has been widely considered as a challenge because of very low production cross section. In this short paper, the breakthrough of searching ground state two proton decay is briefly reviewed, which was made more than 40 years after the early theoretical prediction was proposed.     

远离稳定线原子核的实验研究（Ⅱ）

远离稳定线原子核的实验研究（Ⅱ）罗亦孝（中国科学院近代物理研究所，兰州重离子加速器国家实验室，兰州７３００００）４２丰质子轻稀土核素的合成和衰变性质研究４２１轻稀土区质子滴线Ｚ＝０７４３Ｎ＋１１６附近新β缓发质子先驱核的合成和研究［１６—１...     

远离β稳定线奇异核性质的理论研究

回顾了对远离β稳定线奇特核性质的理论研究现状，并用相对论平均场理论研究了远离β稳定线奇特核的性质．包括轻核的中子晕和质子晕、远离β稳定线核的壳效应和超重核的性质等.The present situation of studies on exotic nuclei far from the β stable line is simply reviewed and then the relativistic mean field study on these nuclei has been carried out. This includes studies on neutron halos and proton halos in light nuclei, on nuclear shell effects of nuclei far from the stability, and on the properties of superheavy nuclei.     

远离稳定线核研究进展

近几年在对远离核的实验研究中,观测到了理论预言的新衰变模式,如45Fe的双质子衰变,β-缓发裂变;对中子滴线外一些核的存在可能性也进行了较多的实验探索和理论分析;开始了对人们一直关注的中子集团存在可能性的实验探索.远离核谱学和衰变性质研究逐渐深入,通过对一些远离核第一激发态能量的系统比较和许多远离核β衰变Q值的测量,以及核质量的精确测量,发现在远离核区,原有的一些幻数消失,代之产生了一些新的幻数,对其产生原因的理论分析做了简要的综述. Recently the predicted new decay model, for instance two-proton decay and β~(-)delayed fission have been observed in the investigations of the nuclei far from stability line. The existence of the nuclei located beyond the drip-line has already been studied experimentally and theoretically. It has been started to search for the neutron cluster in experiment by using neutron-rich nuclei. The researches of the spectroscopy and decay properties of the nuclei far from stability line are more and deeper, and...     

放射性束装置给核结构研究带来的新机遇

利用放射性束装置所提供的高强度和高分辨率的短寿命核束流可达到核中质比的极端值 ,新的现象 ,如中子晕、质子晕、中子皮、质子皮、壳的减弱或消失 ,以及在滴线附近对力的重要性和核物质中质子 -中子对的新超导相的可能存在等不断涌现 .对这些现象进行研究和理解 ,然后回到实验上较易达到的稳定区核去检验人们的理解 ,会对进一步研究核结构、核合成、核天文和自然界基本对称性提供新的机遇 .By making use of the facility for radioactive beams which would be able to supply intense high resolution beams of short lived (radioactive) nuclei, the neutron proton ratio can be extended to extreme values, where some new phenomena such as neutron halo, proton halo, neutron skin, proton skin, growing evidence of the fragility or disappearance of shell structure far from stability, the importance of pairing correlation near drip line, and the possible existence of new superconducting phases of...     

Properties of the β-Delayed Proton Decay of 147Er

The β-delayed proton decay of 147Er is studied experimentally using the 58 Ni＋92Mo reaction at a beam energy of 383 MeV. Based on a He-jet apparatus coupled with a tape transport system, the β-delayed proton radioactivities both from the vδl/2 ground state and the vh11/2 isomer in 147 Er are identified by proton-7 coincidence measurements. By analyzing the time distribution of the 4＋ → 2＋-γ transition in the grand-daughter nucleus 146Dy, a half-life of 1.6 ± 0.2s is determined for the Vh11/2 isomer in 147 Er. The half-life for the ground state of 147Er is estimated to be 3.2±1.2 s.     

质子晕研究的新进展

介绍了质子晕研究在理论和实验方面的最新进展 ,着重讨论了 2 s1 d壳的晕核结构和不同理论模型预示2 6～28P和2 7～ 2 9S中质子晕的存在 ,最近的实验证实了 2 6～ 2 8P核存在一个质子晕.最后简要讨论了质子晕形成的条件. The new progress of proton halo researches in theory and experiment was introduced. Especially the structure of halo nuclei having 2s1d shell and the different models predicting the existence of proton halos in 26～28 P, 27～29 S were discussed. A recent experiment proving the existence of one proton halo in 26～28 P was reviewed and finally the conditions forming proton halo were discussed briefly.     

A～130过渡区核的高自旋态研究

评述了Ａ～１３０过渡区Ｉ、Ｘｅ、Ｃｓ和Ｂａ核的高自旋核结构研究．在这些核中观测到的极为丰富的核结构现象,如质子中子转排竞争、形状共存、带终结、带交叉延迟、Ｓｉｇｎａｔｕｒｅ反转和八极关联等与这些核的价质子、价中子都位于ｈ１１／２支壳及这些核易产生γ形变有关. The studies of high spins states of A ～130 transitional I,Xe,Cs and Ba nuclei are reviewed. The variety of nuclear structure, such as proton neutron alignment competition, shape coexistance, band termination, crossing delay, signature inversion, octupole correlation, etc. observed in these nuclei is closely related to that both the valence proton and neutron of these nuclei are located in the h 11/2 subsell and the nuclei are soft against the γ deformation.     

质子自旋疑难及研究现状

ＮＭＣ实验（ｔｈｅＮｅｗＥｕｒｏｒｅａｎＭｕｏｎＣｏｌｌａｂｏｒａｔｉｏｎ＇ｓＥｘｒｅｒｉｍｅｎｔ）结果是实验向理论提出的一个很有意义的课题．本文总结了质子自旋的唯象研究成果．提出对质子波函数重新作动力学计算可能有助于人们加深对质子自旋的理解． The problem on proton spin and its study,which are interest fields are introducedbriefly,the achievements in the past few years reviewed here. The dynamical calculationfor this problem and its prospect are also mentioned.     

推广的液滴模型及其应用

简单介绍了近年来在研究重核和超重核衰变性质及熔合反应方面取得的理论成果和面临的挑战,着重阐述推广的液滴模型(GLDM) 理论框架及其应用。基于原子核的质量数、质子数以及反应Q 值,GLDM考虑了质量和电荷的不对称性、形状演化、亲近势和温度等,很好地描述了重核和超重核的质子放射性、 衰变、重离子放射性、自发裂变的半衰期和重离子熔合反应截面,同时也研究了原子核的粒子(质子、 、重离子) 放射性与自发裂变的竞争。Recent theoretical achievements and challenges about the fusion and decay properties of heavy and superheavy nuclei are generally introduced. Especially, the Generalized Liquid Drop Model(GLDM) as well as its application are emphatically described. Based on the mass number, proton number and the reaction Q value, the GLDM has taken the mass and charge asymmetry, the shape evolution, the proximity potential, as well as the temperature of nucleus into account, well described the proton radioactivity, the decay, the heavy particle radioactivity, the half life of spontaneous fission of heavy nuclei and superheavy nuclei, and the cross-sections of heavy ion fusion. The competitions between the spontaneous fission and other decay modes such as proton and heavy particle radioactivity, the alpha decay, and so on are also studied.     

23Al的β+延发质子测量

利用ＴＯＦ－ Ｅ和０°注入探测器的方法,鉴别并测量了２３Ａｌβ＋延发质子衰变能谱,通过精密脉冲发生器和计数器测得２３Ａｌ的半衰期 Ｔ１／２＝（４７６±４５）ｍｓ．实验中重现了能量为０．２１６,０．２７８,０．４３８,０．４７９ＭｅＶ的低能衰变质子．另外,还观察到了一个新的β＋延发衰变能级 Ｅｘ＝ ８．９１６ＭｅＶ,并给出了它们的相对强度．     

Design, Fabrication and Test of a Soft X-Ray Even-Order Transmission Grating

Most transmission gratings in the x-ray region work with their first orders and dispersion is limited by the line density achievable with current fabrication technology. We present a novel design of a two-dimensional x-ray transmission grating. The grating works with higher dispersion using its second orders, and the influence from first and third orders can be suppressed. A grating according to the novel design is fabricated and its diffraction performance is tested in comparison with a traditional x-ray transmission grating with the same line density. The novel grating could be especially useful when high dispersion is desired while the fabrication of high-density gratings becomes more difficult.     

Electromagnetic design and optimization of a superconducting quarter wave resonator

Superconducting (SC) cavities currently used for the acceleration of protons at a low velocity range are based on half wave resonators. Due to the rising demand on high current, the issue of beam loading and space charge problems has arisen. Qualities of low cost and high accelerating efficiency are required for SC cavities, which are properly fitted by using an SC quarter wave resonator (QWR). We propose a concept of using QWRs with frequency 162.5 MHz to accelerate high current proton beams. The electromagnetic design and optimization of the prototype have been finished at Peking University. An analytical model derived by the transmission line theory is used to predict an optimal combination of the geometrical parameters, with which the calculation by Microwave Studio shows a good agreement. The thermal analysis to identify the temperature rise of the demountable bottom plate under various levels of thermal contact also has been done, and the maximum increment is less than 0.5 K even though the contact state is poor.     

晕核和推广的Glauber理论

简要介绍了中子晕和质子晕研究的最新实验进展,同时,讨论了近年来发展的同位旋,能量有关的具有晕核结构的Glauber理论及它在描述晕核与核散射时的重要性.The development of new experiments for neutron (or proton) halo is briefly described, while the isospin and energy dependence of Glauber theory and its importance in describing halo nuclei-nucleus scattering are discussed.     

CEBAF和质子G°实验研究

本文简单介绍了美国ＣＥＢＡＦ（连续电子束流加速器）的近况和研究方向,以及Ｃ厅将展开的研究核子内Ｓ夸克成分的极化电子与质子散射宇称破坏不对称性测量的实验,即质子味单态电形状因子Ｇ°实验． The current status and scientific goal of CEBAF (The continuous Electron Beam Accelerator Facility ) are briefly presented. The project of the measurement of the flavor Singlet form factor G°of proton at C hall is outlined. A precise measurement of Parity violating asymmetry in the scattering of polarized electron from a proton target enables one to explore the Strange quark content in the proton.     

对超重核基态性质的系统性研究

对有限力程小液滴模型计算的质子数z=101—130超重核同位素链核的基态性质进行了系统的分析，通过对这些同位素链中处于裂变稳定线上核的平均结合能、四极形变、单质子分离能、双质子分离能和a衰变能等性质的系统研究，显示了质子数Z=108，114，126和中子数N=162，180，196时壳幻数的存在，同时可以看到Z=127之后超重核的基态性质还需要进一步研究。The calculated data by the Finite Range Droplet Model (FRDM) for the ground state properties of super-heavy nuclear isotope chains from Z=101 to Z=130 are analyzed in a global systematic way. Some quantities of the super-heavy nuclei which lie on the line of stability agains fission, such as the mean binding energy, deformation, single and double proton separation energy, as well as the α decay energy indicate the existence of the shell closure positions at Z=108, 114 and 126 and N=162...     

质子与乙烯分子碰撞的密度泛函理论研究(英文)

采用含时局域密度近似与分子动力学相结合的方法研究了不同入射速度的质子与乙烯分子碰撞的动力学。计算了质子的能量损失及碰撞后乙烯分子的电子和离子的运动状态, 研究了质子的入射方向及入射动能对整个系统的碰撞动力学的影响。计算结果表明, 当入射质子的动能较小（E_k0<250 eV）时, 在相同的入射速度下, 当质子垂直于分子平面入射时, 系统的电离最大, 质子俘获的电子多; 当质子的入射动能E_k0>250 eV时, 质子的能量损失与入射方向有密切的关系。In the framework of the time dependent local density approximation (TDLDA),which applied to valence electrons, coupled non adiabatically to molecular dynamics of ions, the microscopic mechanisms of collisions between energetic protons and ethylene are studied. Not only the amount of energy lost of the projectile, but also the electron and vibration excitations of the target are identified. In addition, the influences of the collision orientation on the energy loss of the proton and excitation dynamics of ethylene are discussed. It is found that the ionization is enhanced and more electrons are captured by the proton when the proton with the impact energy less than 250 eV moves perpendicularly to the molecular plane. A strong relation between the proton energy lost and the impact orientation is obtained when the impact energy is larger than 250 eV.     

爆发性核合成与核结构

讨论了天体物理环境中爆发性核合成及其与核结构的紧密关系.用反射不对称壳模型计算了远离稳定线丰中子核148Ba的低能八极转动带,结果与实验很好符合.展示了其应用于不稳定核低能态计算的有效性 ,以及在核天体物理研究中的应用前景.The explosive nucleosynthesis in the astrophysical environment and its close link to nuclear structure are discussed. The low lying octupole bands for neutron rich nucleus 148 Ba far from the stability line have been calculated by the reflection asymmetric shell model and the results are in good agreement with the experimental data, presenting the capability of the model for calculations of the low lying states of unstable nuclei as well as the foreground of application in nuclear astrophysics.     

126Ce的EC/β+衰变

利用187 MeV的40Ca离子轰击同位素靶92Mo, 由熔合蒸发反应生成目标核126Ce。 藉助氦喷嘴快速带传输系统和X-X-t与X-γ-t符合测量, 首次建立了126Ce的EC/β+衰变纲图。 建议了可能属于126Ce一个高自旋同核异能态的衰变, 其β衰变后布居在与126La的高自旋同核异能态相关的低位能级区, 测定的半衰期是57(9) s。 也建议了可能属于126Ce基态的衰变, 其β衰变后布居在与126La的低自旋同核异能态相关的低位能级区,它的半衰期被测定为12(4) s。 但偶偶核126Ce存在高自旋同核异能态的物理原因还有待进一步探究。 Ce was produced by bombarding an enriched target of 92Mo with 187 MeV 40Ca beam and studiedby using a helium jet fast tape transport system in combination with X-γ and γ-γ coincidencemeasurements. An EC/β+ decay scheme of 126Ce was proposed for the first time. A group of low lying states associated with the low spin isomer in 126La feeding by β decay was possibly from the ground state EC/β+ decay of 126Ce with the measured half-life 12(4) s. Another group of low lying states associated with the high spin isomer in 126La feeding by β decay was possibly from a high spin isomer EC/β+ decay of 126Ce with the measured half-life 57(9) s. However, the physical reason for the existence of a high spin isomer in even-even nucleus 126Ce is still an open problem.