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Bronis, A.*; Heberger, F. P.*; Antalic, S.*; Andel, B.*; Ackermann, D.*; Heinz, S.*; Hofmann, S.*; Khuyagbaatar, J.*; Kindler, B.*; Kojouharov, I.*; et al.
Physical Review C, 106(1), p.014602_1 - 014602_12, 2022/07
被引用回数:2 パーセンタイル:49.92(Physics, Nuclear)The decay of excited states in No was investigated by applying the evaporation-residue-conversion-electron correlation technique. Two new isomeric states were observed in No together with the previously known one. Excitation energies of the isomeric states were estimated based on the energies of conversion electrons and rays from correlation chains. These results were in accord with theoretical calculations based on the mean-field models. A tentative decay scheme of isomeric states in No is proposed, and their Nilsson configurations are discussed. The energy decrease of the 11/2[725] Nilsson level for heavy =153 isotones as a function of increasing proton number is confirmed.
Konki, J.*; Khuyagbaatar, J.*; Uusitalo, J.*; Greenlees, P. T.*; Auranen, K.*; Badran, H.*; Block, M.*; Briselet, R.*; Cox, D. M.*; Dasgupta, M.*; et al.
Physics Letters B, 764, p.265 - 270, 2017/01
被引用回数:18 パーセンタイル:79.1(Astronomy & Astrophysics)The new neutron-deficient nuclei Es and Bk were synthesised at the gas-filled recoil separator RITU. They were identified by their radioactive decay chains starting from Es produced in the fusion-evaporation reaction Bi(S,3n)Es. Half-lives of 6(2)s and 22s were obtained for Es and Bk, respectively. Two groups of particles with energies =8.19(3) MeV and 8.09(3) MeV were unambiguously assigned to Es. Electron-capture delayed fission branches with probabilities of 0.16(6) and 0.04(2) were measured for Es and Bk, respectively. These new data show a continuation of the exponential increase of ECDF probabilities in more neutron-deficient isotopes.
Andel, B.*; Andreyev, A. N.; Antalic, S.*; Heberger, F. P.*; Ackermann, D.*; Hofmann, S.*; Huyse, M.*; Kalaninov, Z.*; Kindler, B.*; Kojouharov, I.*; et al.
Physical Review C, 93(6), p.064316_1 - 064316_12, 2016/06
被引用回数:5 パーセンタイル:39.28(Physics, Nuclear)Isomeric states in Po and Po were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions Pr(Fe, )Po and Sm(V, )Po. Several new -ray transitions were attributed to the isomers and - coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in Po, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (11) to (10). The de-excitation of the (11) isomeric level in Po by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV (E3) transition to (8) level of the ground-state band was suggested. Moreover, side feeding to the (4) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting 11 isomers in neighboring Po and Pb isotopes.
Sahin, E.*; Doncel, M.*; Sieja, K.*; De Angelis, G.*; Gadea, A.*; Quintana, B.*; Grgen, A.*; Modamio, V.*; Mengoni, D.*; Valiente-Dobn, J. J.*; et al.
Physical Review C, 91(3), p.034302_1 - 034302_9, 2015/03
被引用回数:26 パーセンタイル:84.22(Physics, Nuclear)The level structure of the neutron-rich Cu, Cu, and Cu isotopes was investigated using multinucleon transfer reactions at Laboratori Nazionali di Legnaro using the AGATA Demonstrator array coupled to the PRISMA magnetic spectrometer. Lifetimes of excited states in Cu nuclei were measured with the recoil-distance Doppler-shift method. The resulting electromagnetic matrix elements for transitions from excited states in Cu nuclei was used to assess the collective or single-particle character of these states. The results are compared with predictions of large-scale shell-model calculations, showing how the proton pf shell evolve as neutrons fill the 1g orbital.
Andreyev, A. N.*; Huyse, M.*; Van Duppen, P.*; Qi, C.*; Liotta, R. J.*; Antalic, S.*; Ackermann, D.*; Franchoo, S.*; Heberger, F. P.*; Hofmann, S.*; et al.
Physical Review Letters, 110(24), p.242502_1 - 242502_5, 2013/06
被引用回数:90 パーセンタイル:93.91(Physics, Multidisciplinary)-decay data for more than 20 nuclei of the most neutron-deificient isotopes in the region from lead to thorium was obtained. The combined analysis allowed us for the first time to clearly show that crossing the Z=82 shell to higher proton numbers strongly accelerates the decay. The analysis support the conjecture that both the N=126 and Z=82 shell closures stongly influence the -formation probability.
Rubert, J.*; Dorvaux, O.*; Gall, B. J. P.*; Greenlees, P. T.*; Asfari, Z.*; Piot, J.*; Andersson, L. L.*; 浅井 雅人; Cox, D. M.*; Dechery, F.*; et al.
Journal of Physics; Conference Series, 420, p.012010_1 - 012010_10, 2013/03
被引用回数:0 パーセンタイル:0.04(Physics, Nuclear)初めての超重元素即発インビーム線分光実験をRfを対象に行った。MIVOC法を用いた大強度Tiビームの開発を行い、実験を成功させた。Rfの回転励起状態をスピン20 まで観測し、その慣性能率を導出した。これらのデータから、陽子数104には大きな変形閉殻が存在しないことが明らかとなった。
Andreyev, A. N.*; Antalic, S.*; Ackermann, D.*; Bianco, L.*; Franchoo, S.*; Heinz, S.*; Heberger, F. P.*; Hofmann, S.*; Huyse, M.*; Kalaninov, Z.*; et al.
Physical Review C, 87(1), p.014317_1 - 014317_8, 2013/01
被引用回数:24 パーセンタイル:80.23(Physics, Nuclear)By using the recoil-fission correlation technique, the exotic process of beta-delayed fission (DF) was unambiguously identified in the very neutron-deficient nuclei At in experiments at the velocity filter SHIP at Gesellschaft fr Schwerionenforschung (GSI). The upper limits for the total kinetic energy release in fission of Po, being the daughter of At after decay, were estimated. The possibility of an unusually high DF probability At is discussed.
Greenlees, P. T.*; Rubert, J.*; Piot, J.*; Gall, B. J. P.*; Andersson, L. L.*; 浅井 雅人; Asfari, Z.*; Cox, D. M.*; Dechery, F.*; Dorvaux, O.*; et al.
Physical Review Letters, 109(1), p.012501_1 - 012501_5, 2012/07
被引用回数:58 パーセンタイル:88.66(Physics, Multidisciplinary)104番元素Rfの回転励起構造をインビーム線核分光の手法により初めて観測することに成功した。Rfは回転励起構造が観測された最も重い原子核であり、今回の結果は重い極限に位置する原子核の一粒子軌道殻構造と対相関に関する貴重な情報を与える。今回の実験で得られたRfの回転状態の慣性能率の値は、陽子数104における変形閉殻の存在を明確に否定し、近年の数多くの自己無撞着平均場モデルの予測と異なる結果を示した。
Heberger, F. P.*; Antalic, S.*; Ackermann, D.*; Kalaninov, Z.*; Heinz, S.*; Hofmann, S.*; Streicher, B.*; Kindler, B.*; Kojouharov, I.*; Kuusiniemi, P.*; et al.
European Physical Journal A, 48(5), p.75_1 - 75_9, 2012/05
被引用回数:26 パーセンタイル:78.16(Physics, Nuclear)Nuclear structure and decay of the isotope No and its decay products Fm and Md were investigated by means of - spectroscopy. Besides the established strong transitions from the 9/2[734] Nilsson level in Fm, populated predominantly by the decay of No, into the ground-state(gs) rotational band, a couple of weaker lines were observed and placed into the Fm level scheme. The transition from the 7/2 level in Es, populated by the decay of Md, into the 9/2 member of the gs rotational band, so far established for other odd-mass Es isotopes, was observed clearly. The GEANT4 simulations were performed to investigate the influence of energy summing between particles and conversion electrons (CE) on the shape of the spectra at different implantation energies, leading to evidence for a weak decay branch of No into the gs of Fm or the ground-state rotational band, respectively.
Antalic, S.*; Heberger, F. P.*; Ackermann, D.*; Heinz, S.*; Hofmann, S.*; Kalaninov, Z.*; Kindler, B.*; Khuyagbaatar, J.*; Kojouharov, I.*; Kuusiniemi, P.*; et al.
European Physical Journal A, 47(5), p.62_1 - 62_12, 2011/05
被引用回数:29 パーセンタイル:82.95(Physics, Nuclear)Nuclear structure and decay of isomer in No were investigated. The isotope was produced by the reaction Ca+Pb. The excitation energy of the known single-particle isomeric state (5/2[622]) was measured by delayed coincidence between -rays and implanted evaporation residues and was placed into the level scheme. In addition, decay of a high-lying multi-quasiparticle isomer in No was studied using e- coincidence measurements. A rotational band populated by its de-excitation was identified in No. A new isomeric state in Fm was observed and a partial-level scheme for this isotope is suggested. In addition transitions from excited levels are reproduced for Md.
Heberger, F. P.*; Antalic, S.*; Sulignano, B.*; Ackermann, D.*; Heinz, S.*; Hofmann, S.*; Kindler, B.*; Khuyagbaatar, J.*; Kojouharov, I.*; Kuusiniemi, P.*; et al.
European Physical Journal A, 43(1), p.55 - 66, 2010/01
被引用回数:71 パーセンタイル:95.19(Physics, Nuclear)-rays decay study of two K isomers in No was performed. Two new transitions of 778 and 856 keV could be attributed to the decay pattern of No (T=275 ms). The population of an excited band built up on this isomer (=8) by the decay of No (198 s) could be proven. A spontaneous fission branch of 2.010 was measured for No, and upper limit of 1.210 was estimated for No. These values demonstrate the high stability of multi-quasiparticle configuration against spontaneous fission.
Heinz, S.*; Comas, V.*; Heberger, F. P.*; Hofmann, S.*; Ackermann, D.*; Burkhard, H. G.*; Gan, Z.*; Heredia, J.*; Khuyagbaatar, J.*; Kindler, B.*; et al.
European Physical Journal A, 38(2), p.227 - 232, 2008/11
被引用回数:24 パーセンタイル:78.18(Physics, Nuclear)Various nuclear reactions like quasi-fission, fusion-fission or particle and cluster evaporation from excited compound nuclei were studied in heavy-ion reactions by using the velocity filter SHIP of GSI. The velocity distributions were measured for the heavier nuclei produced by bombarding Mg, Ni to the target nuclei Pb at energies of 5.9 MeV/A and 8.7 MeV/A. In addition to the evaporation residues produced in the fusion reactions, we found evidence for rotation and quasi-fission of nuclear molecules. The break-up of the systems showed a preferred clustering leading to isotopes in the region 84 88 and 122 127.
Antalic, S.*; Heberger, F. P.*; Hofmann, S.*; Ackermann, D.*; Heinz, S.*; Kindler, B.*; Kojouharov, I.*; Kuusiniemi, P.*; Leino, M.*; Lommel, B.*; et al.
European Physical Journal A, 38(2), p.219 - 226, 2008/11
被引用回数:34 パーセンタイル:84.78(Physics, Nuclear)The radioactive decay of the isotopes Lr and their daughter products was investigated by means of , prompt and delayed conversion electron coincidence spectroscopy. The experiment was carried out at GSI by using the velocity filter SHIP to separate evaporation residues, produced in the reaction Ca+Bi, from the primary beams. In Lr, a second short-lived isomer with a half-life of 1.91 ms was found. For Lr, new data for transitions of levels in Md populated by decay were observed. The constructed level schemes are useful for the nuclear structure theory.
西尾 勝久; Hofmann, S.*; 池添 博; Heberger, F. P.*; Ackermann, D.*; Antalic, S.*; Comas, V. F.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; et al.
Nuclear Physics A, 805(1-4), p.516 - 518, 2008/06
The effects of the orientation of the deformed U target nuclei were investigated in the reaction of Si+U. The cross-sections of the system to overcome the Coulomb barrier were determined by measuring the fission cross-sections at JAEA-tandem accelerator, from which the Coulomb barrier height for the collision of Si to the polar side and the equatorial side of U were determined. The evaporation residue (ER) cross-sections were determined at the velocity filter SHIP of GSI. Significant enhancement of the cross-sections of Sg(4n) in the sub-barrier energy indicates the lowering of the Coulomb barrier at the Polar collisions. However, competition between fusion and quasifission was implied. The cross-sections for Sg(5n) measured at the above barrier energy indicated that there is no significant fusion hindrance at the equatorial collisions. In this contribution, the systematic behavior of the orientation effects of U is discussed by using additionally the data of O+U and Ca+U.
Khuyagbaatar, J.*; Hofmann, S.*; Heberger, F. P.*; Ackermann, D.*; Antalic, S.*; Burkhard, H. G.*; Heinz, S.*; Kindler, B.*; Lisetskiy, A. F.*; Lommel, B.*; et al.
European Physical Journal A, 34(4), p.355 - 361, 2007/12
被引用回数:14 パーセンタイル:67.78(Physics, Nuclear)Isomeric states in Th and Th were produced in the fusion-evaporation reactions of Cr + Dy and identified by means of -rays from the isomeric states. The life-times were determined by measureing the time difference between the signals of the implanted evaporation residues (Th) and the -rays signals, and were obtained to be 1.24 s for Th and 1.4 s for Th. The proton configuration betweens the orbitals of 1h and 2f was assigned to the isomeric states in Th.
西尾 勝久; Hofmann, S.*; 池添 博; Heberger, F. P.*; Ackermann, D.*; Antalic, S.*; Comas, V. F.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; et al.
Journal of Nuclear and Radiochemical Sciences, 8(2), p.73 - 78, 2007/10
Effects of the prolate deformation of U on fusion were studied in the reaction Si + U at bombarding energies close to the Coulomb barrier. The fission cross section was measured at JAEA tandem accelerator to see the enhancement of the cross section in the subbarrier energy due to the lowering of the Coulomb barrier at the collision of the projectile to polar side of U. Evaporation residue cross sections were measured at UNILAC of GSI by using the velocity filter SHIP to determine the fusion probability. In the subbarrier region, we could produce isotope Sg by 4n channel, but fusion hindrance was implied in the analysis. At above barrier energies, we produced Sg by 5n channel. The analysis suggests that there is no fusion hindrance at the equatorial collisions.
Sulignano, B.*; Heinz, S.*; Heberger, F. P.*; Hofmann, S.*; Ackermann, D.*; Antalic, S.*; Kindler, B.*; Kojouharov, I.*; Kuusiniemi, P.*; Lommel, B.*; et al.
European Physical Journal A, 33(4), p.327 - 331, 2007/09
被引用回数:77 パーセンタイル:96.07(Physics, Nuclear)The -isomer with a half-life of 100 ms has been discovered in the nucleus No. The nucleus was produced in the fusion-evaporation reacion Pb(Ca,2n)No. The experiment was carried out at the velocity filter SHIP of GSI. The isomeric state is located at an excitation energy of 1254 keV and is interpreted as a two quasi-neutron state with =8. The isomeric state has direct connection to the rotational states of 8 in No. Also the rotational states of 6 and 4 was feeded via the octupole band with =2. The isomeric state and the ground state was populated with the equal intensity in the fusion-evaporation reaction.
Hofmann, S.*; Ackermann, D.*; Antalic, S.*; Burkhard, H. G.*; Comas, V. F.*; Dressler, R.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; Heberger, F. P.*; et al.
European Physical Journal A, 32(3), p.251 - 260, 2007/06
被引用回数:262 パーセンタイル:99.7(Physics, Nuclear)The fusion reaction of Ca projectiles withU target nuclei was studied at the velocity filter SHIP of GSI. Two decay chains were measured, which fully confirm data that were previously assigned to the isotope 112 in experiments at the Flerov Laboratory in Dubna. Two other events are consistent with a 50% spontaneous fission (SF) branch of this isotope. The mean value obtained for the half-life of 112 is (6.9) s, the energy is (9.5200.015) MeV, and the total kinetic energy (TKE) of SF is (23814) MeV. The half-life of the decay daughter nucleus Ds is (0.18) s, and the TKE of SF is (210) MeV. The cross-section deduced from all four events is (0.72) pb, measured at an excitation energy of 34.6 MeV of the compound nucleus 112.
西尾 勝久; Hofmann, S.*; Heberger, F. P.*; Ackermann, D.*; Antalic, S.*; Comas, V. F.*; Gan, Z.*; Heinz, S.*; Heredia, J. A.*; 池添 博; et al.
AIP Conference Proceedings 891, p.71 - 79, 2007/03
重イオン融合反応Si+UによりSg同位体を合成し、この生成断面積を調べた。実験は、ドイツ重イオン研究所(GSI)で行った。反応エネルギーE=144MeVにおいて、Sgから始まる3つの崩壊連鎖を観測し、断面積67pbを得た。サブバリヤエネルギーE=133MeVで、新同位体Sgを3つ合成し、断面積10pbを得た。これは自発核分裂で崩壊し、半減期は120msであった。これら断面積を統計モデル計算と比較した。融合過程においては、Uの変形を取り入れたチャンネル結合法で捕獲断面積を決定した。この値は、原子力機構のタンデム加速器を用いて行ったSi+Uの核分裂断面積とよく一致した。E=133MeVでの断面積の値は、一次元モデルに比べて10倍大きな値であり、ウランの変形によって断面積が増加することがわかった。しかし、計算との不一致から、準核分裂が何割か存在することが示唆された。クーロン障壁より高いエネルギーE=144MeVではSiはUの赤道面と接触できる。Sgの生成断面積67pbは、統計モデル計算値によく一致し、融合に阻害がなかった。これは、赤道面衝突が融合に有利であることを示唆している。
Kuusiniemi, P.*; Heberger, F. P.*; Ackermann, D.*; Antalic, S.*; Hofmann, S.*; 西尾 勝久; Sulignano, B.*; Kojouharov, I.*; Mann, R.*
European Physical Journal A, 30(3), p.551 - 559, 2006/12
被引用回数:13 パーセンタイル:63.43(Physics, Nuclear)RaとRaの崩壊核分光実験を及び崩壊の測定によって調べた。これらの原子核はEr(Ca,xn)Ra又はEr(Ti,3n)Thで生成されるThの崩壊核種として生成した。蒸発残留核は、ドイツGSIにおける反跳生成核分離装置SHIPで分離され、焦点におけるシリコン検出器で崩壊を測定し、ゲルマニウム検出器で線を測定した。本実験から、次のことが明らかになった。(1)Rnの励起準位に崩壊するRaの線と線のコインシデンスデータから、新たに3つのRnの励起準位のスピン・パリティを決定した。このうち、511keVの励起準位に遷移する崩壊を初めて観測した。(2)Raの8アイソマーから、Rnの8アイソマに遷移する崩壊を初めて観測した。計算で決定したHindrance Factorが1.0であることから、同じスピン間の遷移であることを確認した。