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論文

Electromagnetic properties of low-lying states in neutron-deficient Hg isotopes; Coulomb excitation of $$^{182}$$Hg, $$^{184}$$Hg, $$^{186}$$Hg and $$^{188}$$Hg

Wrzosek-Lipska, K.*; Rezynkina, K.*; Bree, N.*; Zieli$'n$ska, M.*; Gaffney, L. P.*; Petts, A.*; Andreyev, A. N.; Bastin, B.*; Bender, M.*; Blazhev, A.*; et al.

European Physical Journal A, 55(8), p.130_1 - 130_23, 2019/08

 被引用回数:10 パーセンタイル:75.05(Physics, Nuclear)

The neutron-deficient mercury isotopes serve as a classical example of shape coexistence, whereby at low energy near-degenerate nuclear states characterized by different shapes appear. The electromagnetic structure of even-mass $$^{182-188}$$Hg isotopes was studied using safe-energy Coulomb excitation of neutron-deficient mercury beams delivered by the REX-ISOLDE facility at CERN. The population of 0$$^{+}_{1,2}$$, 2$$^{+}_{1,2}$$, and 4$$^{+}_{1}$$ states was observed in all nuclei under study. Reduced $$E2$$ matrix elements coupling populated yrast and non-yrast states were extracted, including their relative signs. These are a sensitive probe of shape coexistence and may be used to validate nuclear models. The experimental results are discussed in terms of mixing of two different configurations and are compared with three different model calculations: the Beyond Mean Field model, the Interacting Boson Model with configuration mixing and the General Bohr Hamiltonian. Partial agreement with experiment was observed, hinting to missing ingredients in the theoretical descriptions.

論文

Detailed $$alpha$$-decay study of $$^{180}$$Tl

Andel, B.*; Andreyev, A. N.; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; Elseviers, J.*; Fedorov, D. V.*; et al.

Physical Review C, 96(5), p.054327_1 - 054327_11, 2017/12

 被引用回数:3 パーセンタイル:27.8(Physics, Nuclear)

A detailed $$alpha$$-decay spectroscopy study of $$^{180}$$Tl has been performed at ISOLDE (CERN). Z-selective ionization by the Resonance Ionization Laser Ion Source (RILIS) coupled to mass separation provided a high-purity beam of $$^{180}$$Tl. Fine-structure $$alpha$$ decays to excited levels in the daughter $$^{176}$$Au were identified and an $$alpha$$-decay scheme of $$^{180}$$Tl was constructed based on an analysis of $$alpha$$-$$gamma$$ and $$alpha$$-$$gamma$$ -$$gamma$$ coincidences. Multipolarities of several $$gamma$$-ray transitions deexciting levels in $$^{176}$$Au were determined. Based on the analysis of reduced $$alpha$$-decay widths, it was found that all $$alpha$$ decays are hindered, which signifies a change of configuration between the parent and all daughter states.

論文

Synthesis, structure, and pressure-induced polymerization of Li$$_{3}$$Fe(CN)$$_{6}$$ accompanied with enhanced conductivity

Li, K.*; Zheng, H.*; 服部 高典; 佐野 亜沙美; Tulk, C. A.*; Molaison, J.*; Feygenson, M.*; Ivanov, I. N.*; Yang, W.*; Mao, H.-K.*

Inorganic Chemistry, 54(23), p.11276 - 11282, 2015/12

 被引用回数:5 パーセンタイル:26.01(Chemistry, Inorganic & Nuclear)

3重結合における圧力誘起重合は共役二重結合を引き起こすと考えられている。比較的低い圧力において重合を起こす金属シアン化物を探索するために、無水のLi$$_{3}$$Fe(CN)$$_{6}$$を合成し、その結晶構造を調べた。実験の結果、CN$$^{-}$$の不可逆な結合が、工業的な装置でも実現できるほど低い圧力で達成された。それに伴い電気伝導度は3倍に増加し、重合化したLi$$_{3}$$Fe(CN)$$_{6}$$はリチウムイオン電池の電極として使える可能性がある。

論文

Hydrogen at zinc vacancy of ZnO; An EPR and ESEEM study

Son, N. T.*; 磯谷 順一*; Ivanov, I. G.*; 大島 武; Janz$'e$n, E.*

AIP Conference Proceedings 1583, p.341 - 344, 2014/02

Defect centers in zinc oxide (ZnO) were investigated using electron paramagnetic resonance (EPR) techniques. Un-doped ZnO samples were irradiated with 2MeV electrons with fluence ranges between 2 and 4$$times$$10$$^{18}$$ /cm$$^{2}$$ at room temperature. As a result of EPR measurements, the spectrum, labeled S1, with small-splitting doublet accompanied by weak satellites was observed. The obtained structure is shown to be the hyperfine structure because of the dipolar interaction between an unpaired electron spin and a nuclear spin of hydrogen (H). The presence of H atom in S1 was confirmed from the observation of the nuclear Zeeman frequency of H in electron spin echo envelope modulation experiments. Considering the observed spin-Hamiltonian parameters, S1 was identified to be the partly H-passivated Zn vacancy, V$$_{Zn}$$$$^{-}$$H$$^{+}$$, with the H$$^{+}$$ ion making a short O-H bond with only one nearest O neighbor of V$$_{Zn}$$ in the basal plane, being off the substitutional site, while the unpaired electron spin, by which the observed EPR signal increased, was localized on the p orbital of another O neighbor also in the basal plane.

論文

$$beta$$-delayed fission of $$^{180}$$Tl

Elseviers, J.*; Andreyev, A. N.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.

Physical Review C, 88(4), p.044321_1 - 044321_13, 2013/10

 被引用回数:38 パーセンタイル:89(Physics, Nuclear)

The detailed analysis of the $$beta$$-delayed fission data of $$^{180}$$Tl is presented. The experiment was performed by producing a pure beam of $$^{180}$$Tl by means of highly selective resonance laser ionization followed by mass separation with the ISOLDE isotope separator. A surprising asymmetric mass distribution of fission fragments from $$^{180}$$Hg, the daughter of $$^{180}$$Tl $$beta$$ decays, was obtained. Here, the energy calibration of the silicon detectors, which is crucial for a proper determination of the fission fragments' energy and mass split, is presented and the total kinetic energy and its dependence on the mass split ratio is discussed. A more precise $$beta$$-delayed fission probability of 3.2(2)$$times$$10$$^{-3}$$$$%$$ was deduced.

論文

$$alpha$$-decay spectroscopy of the chain $$^{179}$$Tl$$^{g}$$ $$rightarrow$$ $$^{175}$$Au$$^{g}$$ $$rightarrow$$ $$^{171}$$Ir$$^{g}$$ $$rightarrow$$ $$^{167}$$Re$$^{m}$$

Andreyev, A. N.*; Liberati, V.*; Antalic, S.*; Ackermann, D.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Diriken, J.*; Elseviers, J.*; Fedorov, D.*; et al.

Physical Review C, 87(5), p.054311_1 - 054311_8, 2013/05

 被引用回数:15 パーセンタイル:70.34(Physics, Nuclear)

$$alpha$$-decay studies of $$^{179}$$Tl$$^{g}$$ and its dahghter products $$^{175}$$Au$$^{g}$$ and $$^{171}$$Ir$$^{g}$$ were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). The nucluesu $$^{175}$$Au$$^{g}$$ has $$alpha$$ decay properties of half-life 207 ms and $$alpha$$-decay energy 6433 keV. The ground state spins and parities for $$^{175}$$Au and $$^{171}$$Ir were determined to be 1/2$$^{+}$$.

論文

New type of asymmetric fission in proton-rich nuclei

Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; Diriken, J.*; et al.

Physical Review Letters, 105(25), p.252502_1 - 252502_5, 2010/12

 被引用回数:181 パーセンタイル:97.19(Physics, Multidisciplinary)

A very exotic process of $$beta$$-delayed fission of $$^{180}$$Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-$$beta$$-decay daughter nucleus $$^{180}$$Hg ($$N$$/$$Z$$ = 1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two $$^{90}$$Zr fragments, with magic $$N$$ = 50 and semi-magic $$Z$$ = 40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly-measured branching ratio for $$beta$$-delayed fission of $$^{180}$$Tl is 3.6(7)$$times$$10$$^{-3}$$ %.

論文

Magnetic resonance studies of defects in electron-irradiated ZnO substrates

Son, N. T.*; Ivanov, I. G.*; Kuznetsov, A. Yu.*; Svensson, B. G.*; Zhao, Q. X.*; Willander, M.*; 森下 憲雄; 大島 武; 伊藤 久義; 磯谷 順一*; et al.

Physica B; Condensed Matter, 401-402, p.507 - 510, 2007/12

 被引用回数:3 パーセンタイル:17.92(Physics, Condensed Matter)

酸化亜鉛(ZnO)中の欠陥の挙動を解明するために、3又は6MeV電子線照射を行ったZnOの光検知磁気共鳴(ODMR)評価を行った。その結果、浅いドナー及びZu空孔に起因するシグナルに加え、スピン1/2を有する幾つかのシグナルが観測され、このうち、LU3及びLU4とラベル付けされたシグナルがキャリアの再結合中心として働くことが判明した。また、400$$^{circ}$$Cまでの熱処理後もLU3,LU4は安定に存在することも併せて明らかとなった。

口頭

陽子過剰原子核の核分裂

西尾 勝久; Andreyev, A. N.*; Elseviers, J.*; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Bree, N.*; Cocolios, T. E.*; Comas, V. F.*; et al.

no journal, , 

陽子過剰な原子核$$^{180}$$Hgの低励起エネルギー核分裂を測定した。CERN-ISOLDEにおいて$$^{180}$$Tlをアイソトープ分離し、このベータ崩壊によって娘核$$^{180}$$Hgを励起さることで、この核分裂を観測した(ベータ崩壊遅延核分裂)。核分裂特性を調べたところ、中性子数50の閉殻を有する$$^{90}$$Zr原子核は生成されず、質量数80と100に収率の最大を有する非対称な核分裂を示した。また、原子力機構タンデム加速器において、陽子過剰原子核のインビーム核分裂実験を行った。この結果、ウランなど従来の核分裂と異なり、励起エネルギーが増加しても質量非対称度が変化しないことがわかった。

口頭

Deep levels in electron irradiated semi-insulating 4H-SiC; Electronic, optical and structural observation

中根 浩貴*; 加藤 正史*; 市村 正也*; 大島 武; Ivanov, I. G.*; Trinh, X. T.*; Son, N. T.*; Janz$'e$n, E.*

no journal, , 

Deep level defects in Silicon Carbide (SiC) were studied using photo-induced current transient spectroscopy (PICTS), electron paramagnetic resonance (EPR) and photoluminescence (PL). Deep levels were introduced into high-purity semi insulating 4H-SiC samples by 2 MeV-electron irradiation. After the electron irradiation, the samples were annealed between 200 and 1000 $$^{circ}$$C. In the samples annealed at 400 $$^{circ}$$C or higher temperatures, we observed six different peaks from PICTS measurements. We labeled these peaks as a, b, c, d, e and f. As a result of the dependence of the peak heights on annealing temperature, the heights of all peaks increase monotonically with annealing temperature. In our previous report, we observed peaks labeled as A and B, which were speculated to be related to C$$_{Si}$$V$$_{C}$$ and the EI4 center identified by EPR. Peak temperatures and annealing behavior of peaks A and B are similar to those of peaks d and f, respectively, while other peaks a, b, c and e were not observed in our previous studies. The PL peaks at 433 and 442 nm were observed in all the studied samples, whereas peaks at 428 and 429 nm were observed in the samples annealed above 200 $$^{circ}$$C, and a peak at 427 nm was observed in samples annealed above 400 $$^{circ}$$C. Considering the annealing temperature dependence of the PICTS and PL peaks, the PL peak at 427 nm may correspond to either one of PICTS peaks a, b, d, e, and f.

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