Search for Extra-Solar Materials as Carriers of Anomalous Noble Gas Isotopes in Meteorites

寻找太阳系外材料作为陨石中异常稀有气体同位素的载体

• 批准号: 60430012
• 负责人: SAKAMOTO Koh
• 金额: $ 5.76万
• 依托单位: KANAZAWA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (A)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1988
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-60430012/
• 关键词: Nucleosynthetic origin; Noble gas isotopes; Photospallation; Photopion reaction; Mass spectrometer; Allende; Murchison; 核理論; 希ガス用質量分析計; Allende隕石; 細分画鉱物分離; Murray; (3,3)共鳴; フラブメンテーション; 希ガス質量分析計; 異常希ガス; π中間子放出反応; Bjurboele隕石; Murchison隕石

1. Nucleosynthetic origin of meteoritic noble gas isotopes of anomalous isotopic compositions were further examined in light of a stellar model prediction by Heymann et al. Our three-isotope analysis has revealed the s- and r-process isotopes more distinctively than previous ones, and shown that the nucleosynthetic model is very promissing in explanation of the observed anomalies in the noble gas abundance. Stellar condition for photodisintegration was found to be the same as deduced earlier by us, i.e. the duration of the silicon burning at peak temperature of T_9=2.05 is (6.5 0.5) x 10^4 sec to yield (^<124>Xe. ^<126>Xe)_p=2.1 0.2 and the observed heavy Xe ratios to constrain the condition of the explosive phase to have a neutron dose of 3.8 x 10^<-7> [mole/cm^3.sec] yielding (^<134>Xe/^<136>Xe)_r=0.675. The carrier phase(s) for s- and r-(＆ p-) isotopes have recently been assigned to very minute SiC and diamond, respectively, but still under debate (see 3. below).2. Energetic photons … More , together with high flux of neutrons, seem to be responsible for reprocessing of chemical elements at supernova explosion. To explore this possibility, photospallation, photofragmentation, photofission and photopion reaction were studied systematically for 13 target nuclei ranging from ^<12>C to ^<209>Bi at bremsstrahlung end point energies of 30-1000 MeV. New characteristic features of their yields and excitation functions were found and examined in light of nuclear theory.3. A sophisticated mass spectrometer of high sensitivity has been constructed and under operation for noble gas isotope study. Meteorite samples were the Allende and Murchison, 10-20 g pieces of which were separately disaggregated by freeze-thaw method and separated into 70 fractions, in case of a 20 g Allende, based on size and density. These fractions were then analyzed for major and trace elements and mineral compositions and for their characteristic features of occurence. Some new types of mineral occurences found in the present work, together with further analysis of noble gas isotopes in the separated fractions, are expected to give observational clues to the origin and formation history of the chemical elements in the solar system. Less

1.根据Heymann等人的恒星模型预测，进一步研究了异常同位素组成的陨石惰性气体同位素的核合成起源。我们的三种同位素分析揭示了s-和r-过程同位素比以前的更明显，并表明核合成模型在解释所观察到的惰性气体丰度异常方面非常有希望。发现光致蜕变的恒星条件与我们以前推导的相同，即在T_9=2.05的峰值温度下，硅燃烧的持续时间为（6.5 ± 0.5）× 10^4秒，产生（？<124>）根据<126>观测到的重中子比，将爆炸相的条件限制为中子剂量为3.8 × 10^<-7>[mole/cm^3.sec]，得到（<134>^mole/<136>^mole）_r=0.675。最近，s-和r-（&amp; p-）同位素的载体相分别被分配给非常微小的SiC和金刚石，但仍在争论中（见3。下面）。2.高能光子 ...更多信息 与高中子通量一起，似乎是超新星爆炸中化学元素再加工的原因。为了探索这一可能性，我们系统地研究了韧致辐射终点能量为30-1000 MeV的13个靶核（从~ 4C到~ 4 Bi）的光致分裂、光致碎裂、光致裂变和质子化反应<12><209>。发现了它们的产额和激发函数的新的特征，并根据核理论进行了检验.一台精密的高灵敏度质谱仪已经建成并投入使用，用于惰性气体同位素研究。陨石样品是阿连德和Murchison，其中10-20克的碎片分别用冻融法分解，并根据大小和密度分成70个部分，如果是20克的阿连德。然后分析这些馏分的主要和微量元素、矿物成分及其产状特征。本文中发现的一些新的矿物占位剂，以及分离组分中稀有气体同位素的进一步分析，可望为太阳系化学元素的起源和形成历史提供观测线索。少

项目成果

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K.Sakamoto 等人：Nucl.Phys.A。

K.Sakamoto, et al.: Nucl.Phys.A. (1989)

K.Sakamoto 等人：Nucl.Phys.A。

K.Sakamoto: Geochem.Jour.23(1). (1989)

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S.SHIBATA: Phys. Rev. C. 35. 254 (1987)

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