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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:6 パーセンタイル:69.74(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:21 パーセンタイル:82.08(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 22
s 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:37.15(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-Dob
n, 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:82.48(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:93 パーセンタイル:93.47(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:0.00(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:26 パーセンタイル:80.55(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 f
r 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:61 パーセンタイル:88.60(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:76.89(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:31 パーセンタイル:83.44(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:76 パーセンタイル:95.35(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 2.0
10
was measured for
No, and upper limit of 1.2
10
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:77.52(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:37 パーセンタイル:85.64(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:16 パーセンタイル:70.64(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:83 パーセンタイル:96.28(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:269 パーセンタイル:99.67(Physics, Nuclear)The fusion reaction of Ca projectiles with
U 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 (9.520
0.015) MeV, and the total kinetic energy (TKE) of SF is (238
14) 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:14 パーセンタイル:64.86(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。