Measurements of the (n, np+d) activation cross sections with 13.4–14.9 MeV neutrons using a fusion neutronics source/JAERI

The activation cross sections for 20 (n, np+d) reactions were measured in the energy range between 13.4 and 14.9 MeV by the activation method. The mass-separated isotopes of ⁸⁷Sr, ^95,100Mo, ¹⁰⁴Ru, ¹⁰⁶Pd, ^113,116Cd, ^118,119,120Sn, ^123,128,130Te, ^184,186W, and ^189,190Os were irradiated. The 16 cross sections, excepting those for ¹¹⁸Sn, ¹²⁸Te and ^184,186W, were obtained for the first time. The d–T neutron source of the fusion neutronics source (FNS) at the Japan Atomic Energy Research Institute (JAERI) was used for irradiation. All cross section values were determined relative to that of the ²⁷Al (n, ) ²⁴Na reaction (ENDF/B-VI). To measure weakly induced activities, an efficiency calibration technique with a well-type HPGe detector was applied. The present results were compared with the comprehensive evaluated data in the JENDL-3.3, the JENDL-Activation File, the ENDF/B-VI and the FENDL/A-2.0. Most of the data in the JENDL-3.3 and the JENDL-Activation File were in good agreement with the present result. However, relative to our values, 13 of the 20 evaluated data in FENDL/A-2.0 were overestimated more than 2 times or underestimated by less than one tenth.     

Alpha induced reactions on Cd up to 38.5 MeV: Experimental and theoretical studies of the excitation functions

The energy dependence of the cross sections of threshold reactions induced by alpha particles on targets of natural cadmium is studied in the energy range from threshold up to 38 MeV. Using a stacked foil irradiation technique and classical gamma-spectroscopy the formation of the radioisotopes ^{110,113m+g,117m}Sn, ^{108m,g,109g,110m,g,111cum,113m,114m,115m,116m,117m,g}In and ^111m,115gCd was assessed. The newly obtained excitation functions were compared with earlier published values, measured either on enriched or natural Cd targets. The results of calculations based on theoretical models of nuclear reactions obtained by the codes ALICE-IPPE, EMPIRE and GNASH are presented. Thick target yields and production routes for some medically relevant radioisotopes are discussed.     

碘-124的生产、标记及在肿瘤PET分子影像的应用

¹²⁴I是一种半衰期较长的正电子核素（T_1/2=4.2 d），由于其生产工艺要求较高、复杂的衰变纲图以及辐射出的超高能量γ射线，在过去很长一段时间里限制了其临床应用。如今，随着回旋加速器生产核素技术的进步及正电子发射型计算机断层显像（PET）技术在肿瘤及药物药代动力学等研究中应用不断拓展，使得¹²⁴I核素标记的化合物成为具有应用价值的核医学PET分子探针。本文主要对¹²⁴I正电子核素的核性质、生产方式、常规标记方法以及在PET分子影像方面的临床应用进行阐述。     

Large mass bolometric detectors for double-beta decay experiments

The authors have developed bolometric detectors with masses of 5.5 g, 20.9 g, and 34 g using TeO₂ crystals for the investigation of ¹³⁰Te, and are developing CaF₂ detectors for double-beta decay search in ⁴⁸Ca, using the luminescence properties of the crystal to improve background rejection. Scintillation of a CaF₂ crystal with 0.03% of Eu doping was observed at 20 mK. A 2.1-g, 0.01%-Eu-doped crystal was used as a bolometer, and a resolution of 50 keV for the double escape peak of ²³²Th was obtained at 60 mK, showing a negligible contribution of the Eu atoms to the crystal heat capacity. Simultaneous detection of light and phonons will allow an efficient background rejection of the ²³⁸U to ²³⁴Th α decay from the ²³⁸U natural series occurring at almost the same energy of the ⁴⁸Ca transition. Background rejection is necessary as even uranium contamination as low as 10^m-10 g/g would make the search impossible     

Neutron economy and nuclear data for transmutation of long-lived fission products

In the study of Self-Consistent Nuclear Energy System, the following 29 long-lived fission products (LLFPs) have been selected to be transmuted into stable or short-lived nuclides: ¹⁰⁶Ru, ¹⁰²Rh, ¹⁰⁹Cd, ¹²⁵Sb, ¹³⁴Cs, ^146,147Pm, ^154,155Eu, ¹⁷¹Tm, ⁸⁵Kr, ⁹⁰Sr, ^93mNb, ^113mCd, ^121mSn, ¹³⁷Cs, ¹⁵¹Sm, ¹⁵²Eu, ^108mAg, ¹⁵⁸Tb, ^166mHo, ⁷⁹Se, ⁹³Zr, ⁹⁴Nb, ⁹⁹Tc, ¹⁰⁷Pd, ¹²⁶Sn, ¹²⁹I, ¹³⁵Cs. In the present study, the number of neutrons necessary for the transmutation of the 29 LLFPs with an FBR was evaluated, and the present status of the (n, γ) and (n,2n) cross section data of the 29 LLFPs in JENDL-3.2 and ENDF/B-VI was investigated. The main results of the present study are as follows: (1)only 0.25 neutron per fission is necessary for the transmutation of the 29 LLFPs with isotopic separation, whereas 6.8 neutrons are necessary with chemical separation, (2)the accuracy of the cross sections is 30 to 100% except for the (n, γ) cross sections of limited nuclides in limited incident neutron energy regions.     

3 MV加速器质谱测量36Cl

在端电压为3 MV的AMS装置上实现³⁶Cl及其他中重核素的高灵敏测量是AMS技术发展的重要方向之一。为进一步提高充气飞行时间探测方法中³⁶S的压低能力,本文研究了³⁶S和³⁶Cl在P10、异丁烷和丙烷气体中的能量歧离和角度歧离。在32 MeV的入射能量下测量了几个地下水样品中³⁶Cl的[JP2]含量,测量结果与72 MeV能量下的测量结果相符。测量结果表明,采用充气飞行时间探测方法在3 MV的串列加速器上测量³⁶Cl时,探测限为³⁶Cl/Cl≈10^-14,当样品中³⁶Cl/Cl≈10^-13时测量不确定度为30%。     

Stopping powers of gases for 40 MeV/u tellurium ions

The stopping powers of six gaseous media have been measured for incident 40 MeV/u ¹²⁵Te heavy ions. The energy losses of ions in various “thicknesses” of gas have been accurately determined. The gases were confined in a cell. The amount of matter traversed by the ions was determined from temperature and pressure measurements. The beam energy before and after slowing down were measured using the LISE magnetic spectrometer at GANIL. These experimental gas stopping powers are lower by about 10% than the corresponding tabulated values for solid media. This means that the gas–solid effect is still significant at 40 MeV/u for Te ions. The projectile effective charges derived from these measurements depend on the target atomic number, thus confirming the trend observed in previous experiments performed with lighter ions or at lower energies.     

235UF6和238UF6同位素分子共振能量转移研究

本文利用长程力碰撞理论计算了²³⁵UF₆和²³⁸UF₆同位素分子间ν₃振动能量的近共振碰撞转移过程,得到了不同温度下共振函数随能量差变化的曲线,发现共振函数的宽度随温度的升高而增大。计算了不同温度下共振转移几率和共振转移速率,发现它们随温度的升高而减小。可见,²³⁵UF₆和²³⁸UF₆同位素分子的平动会降低其共振转移几率和共振转移速率,这为激光光化学法分离铀同位素提供了理论依据。     

Low energy radioactive beams by inversion kinematics

Kinematically focussed radioactive beams of energies lower than 10 MeV/nucleon were produced by means of inversion kinematic in heavy ion induced reactions on ¹H. The characteristics of the produced radioactive beam were examined with the view of performing scattering and reaction experiments. On the basis of these results, a new beamline was constructed to collect and focus the radioactive beams. Using this beamline the elastically scattered spectra of ¹⁵O obtained from the ¹H(¹⁵N, ¹⁵O) reaction were observed with an energy resolution better than 0.6 MeV.     

离子液体/苯并15-冠-5浸渍XAD-7树脂萃取分离锂同位素

以XAD-7树脂为支撑担体制备了含有三种不同咪唑型离子液体([C_8mim][BF_4]、[C_8mim][PF_6]、[C_8mim][(SO_2CF_3)_2N])和萃取剂(苯并15-冠-5)的浸渍树脂,并用于锂同位素的萃取分离。浸渍树脂的红外和扫描电镜表征表明,离子液体成功负载到了树脂上;热重分析表明,该浸渍树脂具有良好的热稳定性。在水相初始pH=5.55时,浸渍树脂具有最佳萃取率。浸渍树脂在LiSCN溶液中具有较高的萃取率,而在CF_3COOLi溶液中呈现较大的单级分离因子,最大单级分离因子达到1.045±0.002。浸渍树脂的萃取平衡时间为2.5~3h。萃取热力学研究表明,该反应为自发过程,温度对体系的影响较小。~6Li富集于固相,~7Li富集在水相。该系列浸渍树脂易于再生,可循环使用。     

Highly enriched isotopes of uranium and transuranium elements for scientific investigation

The paper describes the production of highly enriched isotopes of uranium, plutonium, americium and curium by means of electromagnetic separation for scientific and applied research in physics, chemistry, geology and other fields. The equipment and radiochemical methods used allows to provide the isotopic pure samples in quantities sufficient to set up nuclear physics experiments, to produce reference materials and standard sources for calibration of radiometrical and mass spectrometrical equipment and for use in radionuclear metrology. For a series of nuclei unique characteristics of isotopic enrichment and radiochemical and chemical purity were achieved: ²³³U: 99.97%; ²³⁵U: 99.97%; ²³⁶U: 98.0%; ²³⁸U: 99.997%; ²³⁸Pu: 99.6%; ²³⁹Pu: 99.9977%; ²⁴⁰Pu: 99.9–100%; ²⁴¹Pu: 96.998%; ²⁴²Pu: 97.8–99.96%; ²⁴⁴Pu: 96.7%; ²⁴¹Am: 99.6%; ^242mAm: 85.6%; ²⁴³Am: 99.2–99.94%; ²⁴³Cm: 99.99%; ²⁴⁵Cm: 99.998%; ²⁴⁶Cm: 99.8%; ²⁴⁷Cm: 90%; ²⁴⁸Cm: 97%. Methods of radiochemical and chemical separation, product certification, fabrication of special sources or targets and layers of highly enriched isotopes on various substrates are presented.     

福岛核事故向环境释放的Pu研究进展

福岛核事故向环境释放的放射性核素中包含了锕系元素Pu,其中以极毒组的239Pu、240Pu和高毒组的241Pu为主。本文总结并分析了针对福岛核事故向环境释放的Pu的相关研究。据估计,福岛核事故向环境中排放的239+240Pu总量约为109 Bq,是切尔诺贝利核事故排放量的万分之一。此次事故排放的Pu同位素原子比(240Pu/239Pu和241Pu/239Pu)及活度比(A(238Pu)/A(239+240Pu))明显异于全球沉降值,可作为事故中Pu溯源的判定依据。事故所排放的Pu全部来源于核电站1~3号反应堆堆芯而非乏燃料池。现有研究报道的数据表明,在福岛核电站周围30km范围内的陆地环境中存在来自核事故排放的Pu污染,污染相对严重的"热点"区域和该地区与核电站的相对位置没有明显关联,主要是受地形和降水的影响。而对于人们关心的海洋环境,来自福岛核事故的Pu污染非常小。核事故向海洋中排放的Pu相对于核事故前海洋环境中的Pu污染水平可忽略不计。     

水平衡法与高温转化法在矿泉水氢氧稳定同位素测定中的应用

为了鉴别不同品牌矿泉水标注水源地信息真伪,对11种不同品牌饮用水的氢氧稳定同位素(δD和δ18 O)进行测定。结果表明,水平衡法(GasBench-IRMS)和高温转化法(TC/EA-IRMS)的测定结果一致性较好,两种方法测定6种不同饮用水的δD和δ18 O的平均差异分别为(0.6±1.59)‰和(0.02±0.13)‰。水平衡法需要较长的制备和测定时间,但δD和δ18 O的测定精度明显优于高温转化法。11种饮用水δD和δ18 O变化范围较大,其δD和δ18 O受不同品牌饮用水的水源地降水影响形成明显的地域性。虽然无法区分矿泉水是否由其他类别饮用水伪造,但δD和δ18 O可以为特定区域(如高海拔与沿海地区)以及产地相近的矿泉水水源地鉴别提供依据。     

克量级铀中微量铕和铽的放化分离方法研究

为提高中子诱发铀裂变时低产额裂变产物¹⁵⁶Eu和¹⁶¹Tb产额测量的精度，需获得放化纯的¹⁵⁶Eu和¹⁶¹Tb样品。本工作建立了氢氧化物共沉淀法除铝、氟化钙共沉淀法除铀、TRPO萃取法提取稀土元素、阳离子交换色谱法从混合稀土元素中分离Eu和Tb的流程，可用于大量铀、铝和裂变产物中微量Eu和Tb的分离。在待分离样品中含2 g铀、0.65 g铝和裂变产物的条件下，该流程对Eu、Tb的化学回收率均大于80%，对U、²³⁹Np、⁹⁵Zr、¹⁰³Ru、¹³¹I、¹³²Te、¹⁴⁰Ba、¹⁴⁰La、¹⁴¹Ce、¹⁴⁷Nd等主要干扰物质的去污因子达到106。该方法可满足中子诱发铀裂变时¹⁵⁶Eu和¹⁶¹Tb产额精确测量的要求。     

New production systems at ISOLDE

New target systems for the ISOLDE on-line mass separator facility are presented. Targets of carbides, metal/graphite mixtures, foils of refractory metals, molten metals and oxides have been tested. Beams of high intensity of neutron-rich isotopes of a large number of elements are obtained from a uranium carbide target with a hot plasma-discharge ion source. A target of ZrO₂ has been shown to provide high intensity beams of neutron-deficient isotopes of Mn, Cu, Zn, Ga, Ge, As, Se, Br, Kr and Rb, while a SiC target with a hot plasma ion source gives intense beams of radioactive isotopes of a number of light elements. All these systems are rather chemically unselective. Chemically selective performance has been obtained for several systems, i.e.: the production of neutron-deficient Au from (³He, pχn) reactions on a Pt/graphite target with a hot plasma ion source; the production of neutron-deficient Lu and LuF⁺ and Hf and HfF₃⁺ from a Ta-foil target with a hot plasma ion source under CF₄ addition; the production of neutron-deficient Sr as SrF⁺ and Y as YF₂⁺ form a Nb-foil target with a W surface ionizer under CF₄ addition; the production of neutron-deficient Se as COSe⁺ from a ZrO₂ target with a hot plasma ion source under O₂ addition; and the production of radioactive F from a SiC target with a hot plasma ion source operating in Al vapour.     

Preparation and properties of ^117m Sn（Ⅳ）-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

M310核电站含氢废气处理系统容量分析及优化

核岛含氢废气来自一回路,含有氢气和裂变产生的放射性核素,放射性核素主要是惰性气体包括⁸⁵Kr、^85mKr、⁸⁸Kr、¹³³Xe、¹³⁵Xe,还有少量¹³¹I、¹³²I、¹³³I、¹³⁵I、¹³²Te等。M310核电站广泛使用压缩贮存衰变工艺处理含氢废气,出现了衰变箱容量紧张的问题,制约了一回路吹扫操作,影响大修进程,也形成了安全隐患,亟需改造优化。本文以含氢废气中氢气产生的源头为重点,调查研究各种运行工况及操纵规程、规范,分析气体产生量和组份,判断出关键因素为停堆时容控箱气相空间吹扫过程,通过计算得到气体流量的峰值、总体积和氢气的含量。经过比较分析,在满足放射性衰变前提下,提出了针对各类工艺方案需要配备的合理的系统容量,且具有较好的经济性,避免过大冗余造成浪费,解决了工艺优化的难题。     

High-energy-density electron beam generation in ultra intense laser-plasma interaction

By using a two-dimensional particle-in-cell simulation,we demonstrate a scheme for highenergy-density electron beam generation by irradiating an ultra intense laser pulse onto an aluminum(Al) target.With the laser having a peak intensity of 4?×?1023W cm~(-2),a high quality electron beam with a maximum density of 117 ncand a kinetic energy density up to8.79?×?1018J m~(-3) is generated.The temperature of the electron beam can be 416 Me V,and the beam divergence is only 7.25°.As the laser peak intensity increases(e.g.,1024 W cm~(-2)),both the beam energy density(3.56?×?1019J m~(-3)) and the temperature(545 Me V) are increased,and the beam collimation is well controlled.The maximum density of the electron beam can even reach 180 nc.Such beams should have potential applications in the areas of antiparticle generation,laboratory astrophysics,etc.     

Method for precision measurement of the masses of short-lived nuclides with application of stable isobars

The distinction of the suggested scheme of the experiment is the application of the isobaric doublets method in determining the masses of short-lived nuclides by means of a high-resolution mass spectrometer. This method enables us to considerably decrease the systematic errors of the measurement results in comparison with the previously applied isotopic reference method.

The work was carried out on an experimental complex, the main component of which was a prism mass spectrometer (PMS) with resolution R = 3 × 10⁴, installed on-line with a mass separator and a synchrocyclotron of the LNPI of the Academy of Sciences of Russia. On this installation we measured the masses of the isotopes ^91–97Rb. Samples containing stable reference isotopes ^91,92,94,96Zr, ⁹³Nb or ^95,97Mo were introduced into the ionizer of the PMS for calibration of the mass scale, that was ensured by their ionization simultaneously with radioactive isotopes of rubidium coming from the mass separator. The values of the masses of the stable isotopes used as reference in the suggested method are known with a very high precision (ΔM/M 3×10⁻⁸), therefore they made a negligible contribution to our experimental errors.     

Measurement of the cross sections for the reactions Cr(n,2n)Cr, Zn(n,2n)Zn, Y(n,2n)Y and Zr(n,2n)Zr from 13.5 to 14.8 MeV

Cross section measurements for the reactions ⁵²Cr(n,2n)⁵¹Cr, ⁶⁶Zn(n,2n)⁶⁵Zn, ⁸⁹Y(n,2n)⁸⁸Y and ⁹⁶Zr(n,2n)⁹⁵Zr were carried out in the neutron energy range 13.47–14.79 MeV applying the activation technique. Neutrons were produced via the T(d,n)⁴He reaction, making use of the variation of neutron energy with the emission angle. The neutron fluences incident on the samples were determined relative to the well-evaluated cross section for the reaction ⁹³Nb(n,2n)^92mNb.

The induced γ-ray activities of the irradiated Zn, Zr and Y₂O₃ samples and their monitor foils were measured by means of a calibrated Ge(Li) γ-ray detector at the KFI, Debrecen. At the IRK, Vienna, relative γ-ray measurements using a high-purity Ge detector were combined with integral γ-ray counting by means of a NaI(TI) well-type detector on the Cr, Zn and Zr foils of highest activity and on some Nb monitor foils; integral γ-ray counting only was applied in the case of the Y₂O₃ samples. All necessary corrections were taken into account.

The results are compared to the corresponding results of cross section measurements published in the literature. The uncertainties obtained in this work are considerably smaller in most cases than the uncertainties given by other authors.