Al-Shayeb, B.*; Sachdeva, R.*; Chen, L.-X.*; Ward, F.*; Munk, P.*; Devoto, A.*; Castelle, C. J.*; Olm, M. R.*; Bouma-Gregson, K.*; 天野 由記; et al.
Nature, 578(7795), p.425 - 431, 2020/02
Phage typically have small genomes and depend on their bacterial hosts for replication. We generated metagenomic datasets from many diverse ecosystems and reconstructed hundreds of huge phage genomes, between 200 kbp and 716 kbp in length. Thirty four genomes were manually curated to completion, including the largest phage genomes yet reported. Expanded genetic repertoires include diverse and new CRISPR-Cas systems, tRNAs, tRNA synthetases, tRNA modification enzymes, initiation and elongation factors and ribosomal proteins. Phage CRISPR have the capacity to silence host transcription factors and translational genes, potentially as part of a larger interaction network that intercepts translation to redirect biosynthesis to phage-encoded functions. Some phage repurpose bacterial systems for phage-defense to eliminate competing phage. We phylogenetically define seven major clades of huge phage from human and other animal microbiomes, oceans, lakes, sediments, soils and the built environment. We conclude that large gene inventories reflect a conserved biological strategy, observed across a broad bacterial host range and resulting in the distribution of huge phage across Earth's ecosystems.
Ghys, L.*; Andreyev, A. N.; Huyse, M.*; Van Duppen, P.*; Antalic, S.*; Barzakh, A.*; Capponi, L.*; Cocolios, T. E.*; Cubiss, J.*; Derkx, X.*; et al.
Physical Review C, 100(5), p.054310_1 - 054310_13, 2019/11
The aim of this work was to investigate the -decay properties of Fr and daughter products. Neutron-deficient francium nuclei are produced at ISOLDE-CERN bombarding a UCx target with 1.4 GeV protons. Due to the very high statistics and the high beam purity, improved decay data for Fr and its daughters were obtained. The observation of crossover transitions positioned the isomeric high-spin level of At at an excitation energy of 265(3) keV. Half-life values of 4.47(5) s and 1.28(10) s were extracted for the ground state and isomeric state of At and 52(3) ms for the ground-state decay of Fr.
Barzakh, A. E.*; Cubiss, J. G.*; Andreyev, A. N.; Seliverstov, M. D.*; Andel, B.*; Antalic, S.*; Ascher, P.*; Atanasov, D.*; Beck, D.*; Biero, J.*; et al.
Physical Review C, 99(5), p.054317_1 - 054317_9, 2019/05
Hyperfine-structure parameters and isotope shifts for the 795-nm atomic transitions in At have been measured at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy technique. Magnetic dipole and electric quadrupole moments, and changes in the nuclear mean-square charge radii, have been deduced. A large inverse odd-even staggering in radii, which may be associated with the presence of octupole collectivity, has been observed. Namely, the radius of the odd-odd isotope At has been found to be larger than the average.
Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P.-A.*; 炭竃 聡之*; Taprogge, J.*; Xu, Z. Y.*; et al.
Physics Letters B, 772, p.483 - 488, 2017/09
A new high-spin isomer in the neutron-rich nucleus Cd was populated in the projectile fission of a U beam at the Radioactive Isotope Beam Factory at RIKEN. A half-life of T = 6.3(8) ms was measured for the new state which was tentatively assigned a spin/parity of (15). The isomeric state decays via the emission of a 309-keV ray with multipolarity. The experimental results are compared to shell model calculations performed using state-of-the-art realistic effective interactions and to the neighbouring nucleus Cd. The comparison with calculations shows that adjustments of the pairing and multipole parts of the effective interaction derived from the CD-Bonn nucleon-nucleon potential are required in order to describe the properties of nuclei in the region around Sn.
Barzakh, A.*; Andreyev, A.; Cocolios, T. E.*; de Groote, R. P.*; Fedorov, D. V.*; Fedosseev, V. N.*; Ferrer, R.*; Fink, D. A.*; Ghys, L.*; Huyse, M.*; et al.
Physical Review C, 95(1), p.014324_1 - 014324_12, 2017/01
Hyperfine structure and isotope shifts have been measured for the ground and isomeric states in the neutron deficient isotopes Tl using the 276.9 nm transition. The experiment has been performed at the CERN Isotope Separator On-Line facility using the in-source resonance-ionization laser spectroscopy technique. Spins for the ground states in Tl have been determined as = 1/2. Magnetic moments and changes in the nuclear mean-square charge radii have been deduced. By applying the additivity relation for magnetic moments of the odd-odd Tl nuclei the leading configuration assignments were confirmed. A deviation of magnetic moments for isomeric states in Tl from the trend of the heavier Tl nuclei is observed. The charge radii of the ground states of the isotopes Tl follow the trend for isotonic (spherical) lead nuclei. The noticeable difference in charge radii for ground and isomeric states of Tl has been observed, suggesting a larger deformation for the intruder-based 9/2 and 10 states compared to the ground states. An unexpected growth of the isomer shift for Tl has been found.
Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P. A.*; 炭竃 聡之*; Taprogge, J.*; Xu, Z. Y.*; et al.
Physical Review C, 94(2), p.024303_1 - 024303_8, 2016/08
The decay of the semi-magic nucleus Cd has been studied at the RIBF facility at the RIKEN Nishina Center. The high statistics of the present experiment allowed for a revision of the established level scheme of In and the observation of additional feeding to high lying core-excited states in In. The experimental results are compared to shell-model calculations employing a model space consisting of the full major neutron and proton shells, and good agreement is found.
Van Beveren, C.*; Andreyev, A.; Barzakh, A. E.*; Cocolios, T. E.*; de Groote, R. P.*; Fedorov, D.*; Fedosseev, V. N.*; Ferrer, R.*; Ghys, L.*; Huyse, M.*; et al.
Journal of Physics G; Nuclear and Particle Physics, 43(2), p.025102_1 - 025102_22, 2016/02
-decay spectroscopy of Tl has been performed at the CERN isotope separator on-line (ISOLDE) facility. New fine-structure decays have been observed for both isotopes. -decay branching ratios of 0.089(19), 0.047(6) and 1.22(30) have been deduced for the (10), (7) and (2) states respectively in Tl and a lower limit of 0.49 for the -decay branching ratio of Tl. A new half-life of 9.5(2) s for the (2) state in Tl and 1.9(1) s for the low-spin state in Tl has been deduced. Using - coincidence analysis, multiple rays were observed de-exciting levels in Au fed by Tl decays. The transitions connecting these low-lying states in Au are essential to sort the data and possibly identify bands from inbeam studies in these isotopes. Owing to the complex fine-structure decays and limited knowledge about the structure of the daughter nuclei, only partial level schemes could be constructed for both gold isotopes in the present work. Reduced -decay widths have been calculated and are compared with values obtained in neighboring odd-A and even-A thallium isotopes. Except for the allowed decay of the Tl (10) state, the other fine-structure decays observed in this study are hindered. This points to strong structural changes between parent thallium and daughter gold isotopes.
Van Beveren, C.*; Andreyev, A.; Barzakh, A.*; Cocolios, T. E.*; Fedorov, D.*; Fedosseev, V. N.*; Ferrer, R.*; Huyse, M.*; Kster, U.*; Lane, J. F. W.*; et al.
Physical Review C, 92(1), p.014325_1 - 014325_8, 2015/07
Decay spectroscopy of Tl has been performed at the CERN Isotope Separator On-Line (ISOLDE) facility. An excitation energy of 506.1(1) keV and a half-life of 47.1(7) ms of the intruder based (10) state have been extracted. The internal decay characteristics of this state are determined and discussed, extending the systematics of such states in the even-mass thallium nuclei below neutron midshell at N = 104. The retardation factors of the isomeric M2 and E3 transitions are deduced and compared with retardation factors in neighboring odd-mass and even-mass thallium isotopes. The new information is combined with a review of hindered and unhindered -decay data of Bi populating levels in daughter nuclei Tl and supports the interpretation of the intruder character of the (10) state in Tl.
Taprogge, J.*; Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; Sderstrm, P.-A.*; 炭竃 聡之*; Xu, Z. Y.*; et al.
Physical Review C, 91(5), p.054324_1 - 054324_11, 2015/05
The decay of Cd, produced in relativistic fission of a U beam, was studied at the RIKEN Nishina Center. From the -ray analysis, 31 excited states and 69 ray transitions were established in the level scheme of In, and compared with state-of-the-art shell-model calculations. It was found that the decay of Cd is dominated by Gamow teller transitions, but a non-negligible contribution to the decay is also made by first-forbidden transitions. To estimate the contribution of first-forbidden transitions is important for calculations of the -decay half-lives of nuclei in this region.
Lorusso, G.*; 西村 俊二*; Xu, Z. Y.*; Jungclaus, A.*; Shimizu, Y.*; Simpson, G. S.*; Sderstrm, P.-A.*; Watanabe, H.*; Browne, F.*; Doornenbal, P.*; et al.
Physical Review Letters, 114(19), p.192501_1 - 192501_7, 2015/05
The -decay half-lives of 110 neutron-rich isotopes of the elements from Rb to Sn were measured at the RIBF Facility at RIKEN, Japan. The new data demonstrate the persistence of shell structure far from stability and have direct implications for the -process calculations. In particular, the new half-lives have a global impact on the calculated -process elemental abundances, and alleviate the underproduction of isotopes just above and below the A=130 peak, which in the past required the introduction of shell structure modifications. Reaction-network calculations based on the new data reinforce the notion that the r-process abundance pattern may result from the freeze-out of a (n,)(,n) equilibrium.
Orlandi, R.; Mcher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.
Physics Letters B, 740, p.298 - 302, 2015/01
Single-neutron states in Zn have been populated using the reaction Zn(d,p) at REX-Isolde, CERN. The analysis reveals that the lowest excited states in Zn lie at approximately 1 MeV, and involve neutron orbits above the N=50 shell gap. A 5/2 configuration was assigned to the 983-keV state. Comparison with large-scale shell model calculations supports a robust neutron N=50 shell closure for Ni. These data constitute an important step towards the understanding the magicity of Ni and the structure of nuclei in the region.
Taprogge, J.*; Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Xu, Z. Y.*; Doornenbal, P.*; Lorusso, G.*; Ncher, E.*; Simpson, G. S.*; Sderstrm, P.-A.*; et al.
Physics Letters B, 738, p.223 - 227, 2014/11
The decay of an isomeric state in the neutron-rich nucleus Cd was observed via the detection of internal conversion and Compton electrons. This measurement provided the first experimental information on excited states in this nucleus. The isomer was populated in the projectile fission of a U beam at the RIBF facility at RIKEN. From the measured yields of rays and internal conversion electrons, E3 multipolarity was tentatively assigned to the isomeric transition. A half-life of 3.6(2) ms was determined for this new state which, by comparison with shell-model calculations, was tentatively assigned a spin of (21/2).
Watanabe, H.*; Lorusso, G.*; 西村 俊二*; Otsuka, T.*; Ogawa, K.*; Xu, Z. Y.*; 炭竃 聡之*; Sderstrm, P.-A.*; Doornenbal, P.*; Li, Z.*; et al.
Physical Review Letters, 113(4), p.042502_1 - 042502_6, 2014/07
A new isomer with a half-life of 23.0(8) ms has been identified in Pd at 2406 keV excitation. The proposed spin and parity configuration is 10, with maximally aligned configuration of two neutron hole. -decay from the long-lived isomer was also observed to populated excited states at high spins in Ag. The small energy difference between the 10 and 7 isomers in Pd was interpreted in the frame of the monopole shift of the 1 neutron orbit. The effects of the monopole interaction on the evolution of single-neutron energies below Sn are discussed in terms of central and tensor forces.
Taprogge, J.*; Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Doornenbal, P.*; Lorusso, G.*; Simpson, G.*; Sderstrm, P.-A.*; 炭竃 聡之*; Xu, Z. Y.*; et al.
Physical Review Letters, 112(13), p.132501_1 - 132501_6, 2014/04
A low-lying state in In, the one-proton hole nucleus with respect to double magic Sn, was observed by its decay to the beta emitting isomer. The new state, which was populated both in the beta decay of Cd and after beta-delayed neutron emission from Cd, was identified, at an excitation energy of 1353 keV, as the previously unknown single-hole state with respect to the Sn core. Exploiting this crucial new experimental information, shell-model calculations were performed to study the structure of experimentally inaccessible =82 isotones below Sn. The results evidence a surprising absence of proton subshell closures along the chain of =82 isotones. This finding bears consequences on the evolution of the =82 shell gap along the r-process path.
Rothe, S.*; Andreyev, A. N.*; Antalic, S.*; Borschevsky, A.*; Capponi, L.*; Cocolios, T. E.*; De Witte, H.*; Eliav, E.*; Fedorov, D. V.*; Fedosseev, V. N.*; et al.
Nature Communications (Internet), 4, p.1835_1 - 1835_6, 2013/05
The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of smallest quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential (IP). Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states allowed the deduction of the IP of the astatine atom for the first time. New ab initio calculations were performed to support the experimental result. The measured value of IP(At) serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of super-heavy element 117, the heaviest homologue of astatine.
Chadwick, M. B.*; Herman, M.*; Obloinsk, P.*; Dunn, M. E.*; Danon, Y.*; Kahler, A. C.*; Smith, D. L.*; Pritychenko, B.*; Arbanas, G.*; Arcilla, R.*; et al.
Nuclear Data Sheets, 112(12), p.2887 - 2996, 2011/12
Cullen, D. E.*; Blomquist, R. N.*; Dean, C.*; Heinrichs, D.*; Kalugin, M. A.*; Lee, M.*; Lee, Y. K.*; MacFarlane, R.*; 長家 康展; Trkov, A.*
UCRL-TR-203892, p.1 - 40, 2004/04
熱中性子炉体系において熱中性子散乱は非常に重要であり、熱中性子散乱を正確に取り扱わなければならない。モンテカルロコードで熱中性子散乱を取り扱う場合、データやFree Gasモデルに基づいて散乱解析が行われるが、その取り扱いはコードごとに異なっているのが普通である。また、用いられる熱中性子散乱データが異なれば結果が異なってくる。本研究では、さまざまなモンテカルロコードパッケージ(コードと核データ)を用いて、熱中性子散乱の影響を受けやすい体系において実効増倍率などの積分パラメータをどの程度正確に求めることができるか調べるためのベンチマークを実施した。ベンチマーク計算では、熱中性子散乱の効果が強調されるような非常に簡単なピンセル体系についてデータを用いる場合とFree Gasモデルの場合の実効増倍率を計算し、比較した。熱中性子散乱効果は体系依存性が強く、このベンチマーク体系では5%から12%もあることがわかった。コード間の比較ではにより熱中性子散乱を考慮した場合は実効増倍率で、Free Gasモデルの場合でのばらつきがあることがわかった。
Orlandi, R.; Mcher, D.*; Raabe, R.*; Jungclaus, A.*; Pain, S. D.*; Bildstein, V.*; Chapman, R.*; De Angelis, G.*; Johansen, J. G.*; Van Duppen, P.*; et al.
no journal, ,
Single-neutron states in the = 49 isotope Zn were populated in the Zn(d,p)Zn transfer reaction at REX-ISOLDE, CERN. The combined detection of protons ejected in the reaction and of rays emitted by Zn permitted the identification of the lowest-lying 5/2 and 1/2 excited states. The analysis of proton angular distributions links these states to a significant amount of single-particle strength around 1 MeV, and specifically to the d and s neutron orbits, which lie above the = 50 neutron shell gap. Comparison with large-scale-shell-model calculations supports a robust = 50 shell-closure for Ni. These data constitute a considerable step towards the understanding of the magicity of Ni and of the structure of isotopes in the region.