核电池概述及展望

核电池具有能量密度高、工作稳定可靠、无需人工干预等优点，在需要长期稳定供电的场合具有独特优势，其中热转换式核电池(RTG)是技术最为成熟且应用最早的一类，而β辐射伏特效应核电池已有商业化案例。目前，在β辐射伏特效应核电池研究中存在着放射源自吸收效应浪费能量、转化效率低、换能器件辐射损伤严重等问题，而对于一个实际的核电池，由于放射源自身不断衰变的属性，导致源的成分及其活度随着时间而发生变化，最终影响核电池的电学性能，其影响程度需要加以深入研究。本文以时间轴的形式对核电池的发展进行了全面回顾，简要介绍多种主流类型核电池的原理和应用范围；对于β辐射伏特效应核电池，指出放射源的自吸收是其中的关键科学问题。对于使用63Ni和TiT₂放射源的核电池，给出了其电学性能随时间变化的规律；指出对于某一特定结构的β辐射伏特效应核电池设计，在前期的模拟优化环节中，精细计算是至关重要的；最后提出了将放射源与换能材料相结合、使用含有较重同位素的换能器件的设想，这些设想有利于解决放射源自吸收问题、提高核电池输出功率和减轻辐射损伤的影响。     

弱形变双奇核158Tm中的旋称反转

通过融合蒸发反应¹⁴⁴Nd(¹⁹F,5n)布居了双奇核¹⁵⁸Tm的高自旋态. 扩展了原来已知的带结构, 并建立了一条新转动带. 通过与相邻核的比较, 讨论¹⁵⁸Tm核中两条四准粒子带的内禀组态, 并分别指定为πh_11/2\otimes νh_9/2(α=+1/2)\otimes (νi_13/2)²和πh_11/2\otimes νh_9/2(α=－1/2)\otimes (νi_13/2)² 组态. 建立在πh_11/2\otimes νi_13/2组态上的转动带被观测到呈现持续旋称反转现象, 而前述的两条高自旋区的 四准粒子转动带也呈旋称反转. 对这两种类型的旋称反转现象的可能机制进行了简单而定性的讨论.     

Lifetimes of Excited Levels in ^131Ce

The fusion-evaporation reaction ^116Sn (^19F, p3n)^131 Ce at projectile energy of 95 MeV is used to populate high spin states in ^131Ce. The de-exciting γ-rays are detected in γ-γ coincidence measurement with Compton-suppressed BGO-HPGe detectors. Level lifetimes of ^131 Ce were determined by using the Doppler shift attenuation method.The experimental results indicate that collectivity of ^131 Ce is reduced relative to that of ^130Ce and it follows that deformation decreases with increase of the neutron number on the basis of systematic comparison of transition quadrupole moments for the light cerium isotopes.     

双奇核中π1/2－[541]⊙νi13/2带的系统学特征

通过束流能量为97MeV的¹⁵²Sm(¹⁹F,5n)¹⁶⁶Lu熔合蒸发反应,用在束γ(谱学方法研究了¹⁶⁶的高自旋态,建立了5条转动带,其中3条带是本实验中首次确定的.发现了π1/2^－[541]⊙ν5/2⁺[642]带的低自旋旋称反转现象,该带的反转点自旋值17.5h同A=170区奇奇核的π1/2^－[541]⊙νi_13/2带的反转点变化趋势非常相符.     

Lifetimes of High Spin States in an Odd-Proton Nucleus 129Cs

Lifetimes of high spin states in 129Cs axe measured using the Doppler shift attenuation method. The high spin states of 129 Cs axe populated following the fusion evaporation reaction 124 Sn（UB, 6n）129 Cs at a beam energy of 65 MeV. The reduced transition probabilities B（E2） and the transition quadrupole moments Qt in the negativeand positive-paxity bands are deduced. The experimental results indicate that the Qt values of the negative parity band are smaller than those of the positive parity bands, probably due to different γ-deformation driving effects of different proton orbitals. The Qt values exhibit a considerable increase near the band crossing region in these bands. This behavior demonstrates that nuclear shape changing results from the neutron or proton alignments. The signature splitting of the πh11/2 and πg7/2 bands shows the opposite changing trend after backbending due to the h11~2 neutron and h11/2 proton alignments, respectively.     

New band structures in ~（107）Ag

High spin states in ¹⁰⁷Ag are studied via the ¹⁰⁰Mo(¹¹B, 4n)¹⁰⁷Ag reaction at an incident beam energy of 60 MeV. Prompt γ-γ coincidence and DCO ratios are measured by the detector arrays in CIAE. The level scheme has been updated and a new negative band belonging to ¹⁰⁷Ag is identified. The new negative side band has been constructed and its configuration is tentatively assigned to πg_9/2 νh_11/2(g_7/2/d_5/2).     

Doublet bands in 128La and systematic features of energy separationof doublet bands observed in the A～130 mass region

High spin states of 128La have been studied through the fusion-evaporation reaction 118Sn(14N,4n) 128La at a beam energy of 69 MeV. A positive-parity side band with the same configuration as that of the yrast band has been identified. Moreover, it is noted that the energy separation △E(I) = E(I)side-E(I)yrast of all doublet bands reported in odd-odd nuclei in the A～130 mass region exhibit a staggering pattern systematically, and they stagger up at even-spin and stagger down at odd-spin.     

A tentative method for assigning the configuration of a triaxial nuclei in TRS

A tentative method based on the principle of minimum energy is put forward for assigning the reasonable configuration of a triaxial nucleus in TRS. This method is proved by the TSD of ¹⁶⁷Lu nucleus that has been calculated previously by TRS.     

大质量样品厚度对中子活化定量分析的影响和修正

滑石粉的主要化学成分是Mg3[Si_4010](OH)_2,通过检测面粉中~(24)Mg和~(28)Si原子核的含量,可以计算出面粉中滑石粉的含量.利用中子活化分析方法测量面粉中~(24)Mg和~(28)Si原子核的含量问题时,被测样品内部中子通量和能量随厚度的变化以及γ射线自吸收效应会对测量结果有较大的影响.利用MCNP5 (Monte Carlo N-particle transport code system 5)模拟了中子通量和能量与样品厚度变化的关系,并利用氦3正比计数管测量样品不同厚度处中子通量,结果显示MCNP5模拟结果与实验测量结果基本相符.通过MCNP5模拟和碘化钠探测器测量,研究了γ射线自吸收效应与样品厚度的关系,确定了6.6 cm的样品厚度为最佳实验条件,根据模拟结果给出了特征γ射线计数与样品厚度的关系式,并与实验进行对比,结果符合得较好.     

Theoretical Prediction of Diamond Betavoltaic Batteries Performance Using ~(63)Ni

A diamond p–n junction is used to convert the decay energy of ~(63)Ni source into electrical energy. The selfabsorption effect of the ~(63)Ni source, the backscatter process and the transport process of beta particles in diamond materials are studied. Then the theoretical maximum of electrical properties and the energy conversion efficiencies of diamond-~(63)Ni p–n junction batteries are achieved. Finally, a feasible design of p~+p~-n~+junction battery, which has the maximum output power density of 0.42 μW/cm~2 and the optimal device conversion efficiency of 26.8%,is proposed.