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8 results on '"J. Tscheuschner"'

1. Pairing Forces Govern Population of Doubly Magic Ca54 from Direct Reactions

Author

J. M. Gheller, S. Y. Park, K. Yoneda, Masaki Sasano, P. A. Söderström, D. Sohler, D. Körper, H. Simon, A. Gillibert, K. Miki, Satoshi Takeuchi, Yasuhiro Togano, M. MacCormick, R.-B. Gerst, Duo Yan, Tomohiro Uesaka, Fabia Schindler, V. Wagner, B. D. Linh, M. Holl, A. Corsi, N. Paul, Igor Gašparić, H. N. Liu, P. Koseoglou, E. Sahin, Yosuke Kondo, T. Lokotko, T. Isobe, Victor Vaquero, M. L. Cortés, V. Werner, Takashi Nakamura, W. Rodriguez, Zaihong Yang, A. Delbart, S. Franchoo, F. Château, V. Lapoux, P. Doornenbal, K. I. Hahn, L. Stuhl, I. Murray, C. Caesar, Kazuyuki Ogata, C. Lehr, T. Kobayashi, X. X. Xu, C. Hilaire, Si-Ge Chen, Yutaka Utsuno, V. Panin, A. Giganon, Jenny Lee, N. L. Achouri, L. X. Chung, Y. L. Sun, K. Moschner, Yuya Kubota, D. M. Rossi, H. Baba, F. Flavigny, Masahiro Yasuda, L. Zanetti, Kathrin Wimmer, Dong-Wook Kim, O. Aktas, F. Browne, S. Wang, A. Obertelli, J. Kahlbow, Hiroyoshi Sakurai, T. Motobayashi, Julien Gibelin, K. Boretzky, D. Calvet, David Steppenbeck, H. Törnqvist, Thomas Aumann, Nobuyuki Chiga, T. Koiwai, Kazuki Yoshida, Hideaki Otsu, Hirofumi Yamada, and J. Tscheuschner

Subjects
Physics, education.field_of_study, Proton, 010308 nuclear & particles physics, Nuclear Theory, Population, Nuclear shell model, General Physics and Astronomy, 01 natural sciences, 7. Clean energy, Pairing, Excited state, 0103 physical sciences, Neutron, Atomic physics, Nuclear Experiment, 010306 general physics, Nucleon, Ground state, education
Abstract

Direct proton-knockout reactions of ^{55}Sc at ∼220 MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of ^{54}Ca were investigated through γ-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the ^{55}Sc ground state with states in ^{54}Ca. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of ^{55}Sc, valence proton removals populated predominantly the ground state of ^{54}Ca. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

Published
2021
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2. Extending the Southern Shore of the Island of Inversion to F28

Author

J. Mayer, Noritsugu Nakatsuka, Michael Thoennessen, A. Gillibert, Ákos Horváth, Q. Deshayes, Yosuke Kondo, J. Tscheuschner, Nasser Kalantar-Nayestanaki, J. M. Gheller, István Kuti, M. Shikata, Thomas Aumann, C. Caesar, J. Tsubota, A. Revel, N. L. Achouri, W. He, Z. Elekes, Calem Hoffman, Shoichiro Kawase, Heiko Scheit, J. Kahlbow, Masahiro Yasuda, H. Simon, H. Sato, K. Yoneda, A. Horvat, K. Nakano, Igor Gašparić, T. Ozaki, H. Chae, J. A. Tostevin, L. Stuhl, K. Miki, F. de Oliveira Santos, H. L. Crawford, D. Calvet, Stefanos Paschalis, S. Masuoka, T. Isobe, A. Obertelli, Tomoki Saito, Momoko Tanaka, N. A. Orr, Shoko Koyama, Nobuyuki Chiga, L. Atar, Y. Satou, P. Fallon, Atsumi Saito, Zsolt Dombrádi, H. Törnqvist, Jongwon Hwang, A. Corsi, Julien Gibelin, K. Boretzky, A. Delbart, D. M. Rossi, H. Baba, Masaki Sasano, D. Sohler, V. Lapoux, M. A. Najafi, S. K. Kim, A. Hirayama, H. Al Falou, K. Kisamori, T. Tomai, V. Panin, P. Schrock, Takashi Nakamura, Yasuhiro Togano, M.N. Harakeh, M. Holl, Zaihong Yang, F. Nowacki, T. Kobayashi, Cenxi Yuan, D. Körper, Tomohiro Uesaka, Thomas Nilsson, C. A. Douma, Simon Lindberg, Hideaki Otsu, O. Sorlin, T. Murakami, Yohei Shimizu, Fabia Schindler, Franck Delaunay, F. M. Marqués, and Satoshi Takeuchi

Subjects
Physics, Proton, Island of inversion, General Physics and Astronomy, 01 natural sciences, Spectral line, Momentum, 0103 physical sciences, Neutron, Atomic physics, 010306 general physics, Nucleon, Spectroscopy, Ground state
Abstract

Detailed spectroscopy of the neutron-unbound nucleus 28 F has been performed for the first time following proton/neutron removal from 29 Ne / 29 F beams at energies around 230 MeV / nucleon . The invariant-mass spectra were reconstructed for both the 27 F ( * ) + n and 26 F ( * ) + 2 n coincidences and revealed a series of well-defined resonances. A near-threshold state was observed in both reactions and is identified as the 28 F ground state, with S n ( 28 F ) = − 199 ( 6 ) keV , while analysis of the 2 n decay channel allowed a considerably improved S n ( 27 F ) = 1620 ( 60 ) keV to be deduced. Comparison with shell-model predictions and eikonal-model reaction calculations have allowed spin-parity assignments to be proposed for some of the lower-lying levels of 28 F . Importantly, in the case of the ground state, the reconstructed 27 F + n momentum distribution following neutron removal from 29 F indicates that it arises mainly from the 1 p 3 / 2 neutron intruder configuration. This demonstrates that the island of inversion around N = 20 includes 28 F , and most probably 29 F , and suggests that 28 O is not doubly magic.

Published
2020
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3. Fragmentation of Single-Particle Strength around the Doubly Magic Nucleus Sn132 and the Position of the 0f5/2 Proton-Hole State in In131

Author

Hiroyoshi Sakurai, J. Tscheuschner, Yosuke Kondo, A. Bracco, D. Semmler, S. Nishimura, T. Motobayashi, Ryo Taniuchi, N. Imai, Kazuo Ieki, A. Jungclaus, Ismael Martel, F. Camera, P. Schrock, Heiko Scheit, Juzo Zenihiro, Andreas Zilges, V. Derya, D. S. Ahn, K. Boretzky, Yasuhiro Togano, R. Avigo, M.N. Harakeh, D. Symochko, Hiroyuki Takeda, T. Kubo, Shoko Koyama, D. M. Rossi, M. Shikata, H. Baba, Agnese Giaz, Haik Simon, T. Ozaki, J. L. Rodriguez-Sanchez, P. Doornenbal, David Steppenbeck, Atsumi Saito, I. Syndikus, C. Caesar, M. Heil, Si-Ge Chen, J. A. Tostevin, J. Tsubota, Nagao Kobayashi, Deniz Savran, Yoshiaki Shiga, U. Garg, Marina Petri, N. Nakatsuka, Masafumi Matsushita, Toshiyuki Sumikama, Naohito Inabe, Victor Vaquero, Takashi Nakamura, B. Million, J. Endres, Satoshi Takeuchi, A. Horvat, Y. Shimizu, E. V. Litvinova, K. Yoneda, H. Suzuki, O. Wieland, Rene Reifarth, Hideaki Otsu, H. Wang, Fabia Schindler, Shuichi Ota, Nasser Kalantar-Nayestanaki, M. Nishimura, Thomas Aumann, and N. Fukuda

Subjects
Physics, medicine.anatomical_structure, Fragmentation (mass spectrometry), Astrophysics::High Energy Astrophysical Phenomena, Excited state, 0103 physical sciences, Magic (programming), medicine, General Physics and Astronomy, Atomic physics, 010306 general physics, 01 natural sciences, Nucleus
Abstract

Spectroscopic factors of neutron-hole and proton-hole states in 131Sn and 131In, respectively, were measured using one-nucleon removal reactions from doubly magic 132Sn at relativistic energies. For 131In, a 2910(50)-keV γ ray was observed for the first time and tentatively assigned to a decay from a 5=2− state at 3275(50) keV to the known 1=2− level at 365 keV. The spectroscopic factors determined for this new excited state and three other single-hole states provide first evidence for a strong fragmentation of singlehole strength in 131Sn and 131In. The experimental results are compared to theoretical calculations based on the relativistic particle-vibration coupling

Published
2020
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4. Fragmentation of Single-Particle Strength around the Doubly Magic Nucleus ^{132}Sn and the Position of the 0f_{5/2} Proton-Hole State in ^{131}In

Author

V, Vaquero, A, Jungclaus, T, Aumann, J, Tscheuschner, E V, Litvinova, J A, Tostevin, H, Baba, D S, Ahn, R, Avigo, K, Boretzky, A, Bracco, C, Caesar, F, Camera, S, Chen, V, Derya, P, Doornenbal, J, Endres, N, Fukuda, U, Garg, A, Giaz, M N, Harakeh, M, Heil, A, Horvat, K, Ieki, N, Imai, N, Inabe, N, Kalantar-Nayestanaki, N, Kobayashi, Y, Kondo, S, Koyama, T, Kubo, I, Martel, M, Matsushita, B, Million, T, Motobayashi, T, Nakamura, N, Nakatsuka, M, Nishimura, S, Nishimura, S, Ota, H, Otsu, T, Ozaki, M, Petri, R, Reifarth, J L, Rodríguez-Sánchez, D, Rossi, A T, Saito, H, Sakurai, D, Savran, H, Scheit, F, Schindler, P, Schrock, D, Semmler, Y, Shiga, M, Shikata, Y, Shimizu, H, Simon, D, Steppenbeck, H, Suzuki, T, Sumikama, D, Symochko, I, Syndikus, H, Takeda, S, Takeuchi, R, Taniuchi, Y, Togano, J, Tsubota, H, Wang, O, Wieland, K, Yoneda, J, Zenihiro, and A, Zilges

Abstract

Spectroscopic factors of neutron-hole and proton-hole states in ^{131}Sn and ^{131}In, respectively, were measured using one-nucleon removal reactions from doubly magic ^{132}Sn at relativistic energies. For ^{131}In, a 2910(50)-keV γ ray was observed for the first time and tentatively assigned to a decay from a 5/2^{-} state at 3275(50) keV to the known 1/2^{-} level at 365 keV. The spectroscopic factors determined for this new excited state and three other single-hole states provide first evidence for a strong fragmentation of single-hole strength in ^{131}Sn and ^{131}In. The experimental results are compared to theoretical calculations based on the relativistic particle-vibration coupling model and to experimental information for single-hole states in the stable doubly magic nucleus ^{208}Pb.

Published
2019

5. Magicity versus Superfluidity around ^{28}O viewed from the Study of ^{30}F.

Author

Kahlbow J, Aumann T, Sorlin O, Kondo Y, Nakamura T, Nowacki F, Revel A, Achouri NL, Al Falou H, Atar L, Baba H, Boretzky K, Caesar C, Calvet D, Chae H, Chiga N, Corsi A, Delaunay F, Delbart A, Deshayes Q, Dombrádi Z, Douma CA, Elekes Z, Gašparić I, Gheller JM, Gibelin J, Gillibert A, Harakeh MN, Hirayama A, Holl M, Horvat A, Horváth Á, Hwang JW, Isobe T, Kalantar-Nayestanaki N, Kawase S, Kim S, Kisamori K, Kobayashi T, Körper D, Koyama S, Kuti I, Lapoux V, Lindberg S, Marqués FM, Masuoka S, Mayer J, Miki K, Murakami T, Najafi M, Nakano K, Nakatsuka N, Nilsson T, Obertelli A, Orr NA, Otsu H, Ozaki T, Panin V, Paschalis S, Rossi DM, Saito AT, Saito T, Sasano M, Sato H, Satou Y, Scheit H, Schindler F, Schrock P, Shikata M, Shimada K, Shimizu Y, Simon H, Sohler D, Stuhl L, Takeuchi S, Tanaka M, Thoennessen M, Törnqvist H, Togano Y, Tomai T, Tscheuschner J, Tsubota J, Uesaka T, Wang H, Yang Z, Yasuda M, and Yoneda K

Abstract

The neutron-rich unbound fluorine isotope ^{30}F_{21} has been observed for the first time by measuring its neutron decay at the SAMURAI spectrometer (RIBF, RIKEN) in the quasifree proton knockout reaction of ^{31}Ne nuclei at 235  MeV/nucleon. The mass and thus one-neutron-separation energy of ^{30}F has been determined to be S_{n}=-472±58(stat)±33(sys)  keV from the measurement of its invariant-mass spectrum. The absence of a sharp drop in S_{n}(^{30}F) shows that the "magic" N=20 shell gap is not restored close to ^{28}O, which is in agreement with our shell-model calculations that predict a near degeneracy between the neutron d and fp orbitals, with the 1p_{3/2} and 1p_{1/2} orbitals becoming more bound than the 0f_{7/2} one. This degeneracy and reordering of orbitals has two potential consequences: ^{28}O behaves like a strongly superfluid nucleus with neutron pairs scattering across shells, and both ^{29,31}F appear to be good two-neutron halo-nucleus candidates.

Published
2024
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6. Pairing Forces Govern Population of Doubly Magic ^{54}Ca from Direct Reactions.

Author

Browne F, Chen S, Doornenbal P, Obertelli A, Ogata K, Utsuno Y, Yoshida K, Achouri NL, Baba H, Calvet D, Château F, Chiga N, Corsi A, Cortés ML, Delbart A, Gheller JM, Giganon A, Gillibert A, Hilaire C, Isobe T, Kobayashi T, Kubota Y, Lapoux V, Liu HN, Motobayashi T, Murray I, Otsu H, Panin V, Paul N, Rodriguez W, Sakurai H, Sasano M, Steppenbeck D, Stuhl L, Sun YL, Togano Y, Uesaka T, Wimmer K, Yoneda K, Aktas O, Aumann T, Boretzky K, Caesar C, Chung LX, Flavigny F, Franchoo S, Gasparic I, Gerst RB, Gibelin J, Hahn KI, Holl M, Kahlbow J, Kim D, Körper D, Koiwai T, Kondo Y, Koseoglou P, Lee J, Lehr C, Linh BD, Lokotko T, MacCormick M, Miki K, Moschner K, Nakamura T, Park SY, Rossi D, Sahin E, Schindler F, Simon H, Söderström PA, Sohler D, Takeuchi S, Törnqvist H, Tscheuschner J, Vaquero V, Wagner V, Wang S, Werner V, Xu X, Yamada H, Yan D, Yang Z, Yasuda M, and Zanetti L

Abstract

Direct proton-knockout reactions of ^{55}Sc at ∼220  MeV/nucleon were studied at the RIKEN Radioactive Isotope Beam Factory. Populated states of ^{54}Ca were investigated through γ-ray and invariant-mass spectroscopy. Level energies were calculated from the nuclear shell model employing a phenomenological internucleon interaction. Theoretical cross sections to states were calculated from distorted-wave impulse approximation estimates multiplied by the shell model spectroscopic factors, which describe the wave function overlap of the ^{55}Sc ground state with states in ^{54}Ca. Despite the calculations showing a significant amplitude of excited neutron configurations in the ground-state of ^{55}Sc, valence proton removals populated predominantly the ground state of ^{54}Ca. This counterintuitive result is attributed to pairing effects leading to a dominance of the ground-state spectroscopic factor. Owing to the ubiquity of the pairing interaction, this argument should be generally applicable to direct knockout reactions from odd-even to even-even nuclei.

Published
2021
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7. Extending the Southern Shore of the Island of Inversion to ^{28}F.

Author

Revel A, Sorlin O, Marqués FM, Kondo Y, Kahlbow J, Nakamura T, Orr NA, Nowacki F, Tostevin JA, Yuan CX, Achouri NL, Al Falou H, Atar L, Aumann T, Baba H, Boretzky K, Caesar C, Calvet D, Chae H, Chiga N, Corsi A, Crawford HL, Delaunay F, Delbart A, Deshayes Q, Dombrádi Z, Douma CA, Elekes Z, Fallon P, Gašparić I, Gheller JM, Gibelin J, Gillibert A, Harakeh MN, He W, Hirayama A, Hoffman CR, Holl M, Horvat A, Horváth Á, Hwang JW, Isobe T, Kalantar-Nayestanaki N, Kawase S, Kim S, Kisamori K, Kobayashi T, Körper D, Koyama S, Kuti I, Lapoux V, Lindberg S, Masuoka S, Mayer J, Miki K, Murakami T, Najafi M, Nakano K, Nakatsuka N, Nilsson T, Obertelli A, de Oliveira Santos F, Otsu H, Ozaki T, Panin V, Paschalis S, Rossi D, Saito AT, Saito T, Sasano M, Sato H, Satou Y, Scheit H, Schindler F, Schrock P, Shikata M, Shimizu Y, Simon H, Sohler D, Stuhl L, Takeuchi S, Tanaka M, Thoennessen M, Törnqvist H, Togano Y, Tomai T, Tscheuschner J, Tsubota J, Uesaka T, Yang Z, Yasuda M, and Yoneda K

Abstract

Detailed spectroscopy of the neutron-unbound nucleus ^{28}F has been performed for the first time following proton/neutron removal from ^{29}Ne/^{29}F beams at energies around 230  MeV/nucleon. The invariant-mass spectra were reconstructed for both the ^{27}F^{(*)}+n and ^{26}F^{(*)}+2n coincidences and revealed a series of well-defined resonances. A near-threshold state was observed in both reactions and is identified as the ^{28}F ground state, with S_{n}(^{28}F)=-199(6)  keV, while analysis of the 2n decay channel allowed a considerably improved S_{n}(^{27}F)=1620(60)  keV to be deduced. Comparison with shell-model predictions and eikonal-model reaction calculations have allowed spin-parity assignments to be proposed for some of the lower-lying levels of ^{28}F. Importantly, in the case of the ground state, the reconstructed ^{27}F+n momentum distribution following neutron removal from ^{29}F indicates that it arises mainly from the 1p_{3/2} neutron intruder configuration. This demonstrates that the island of inversion around N=20 includes ^{28}F, and most probably ^{29}F, and suggests that ^{28}O is not doubly magic.

Published
2020
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8. Fragmentation of Single-Particle Strength around the Doubly Magic Nucleus  ^{132}Sn and the Position of the 0f_{5/2} Proton-Hole State in ^{131}In.

Author

Vaquero V, Jungclaus A, Aumann T, Tscheuschner J, Litvinova EV, Tostevin JA, Baba H, Ahn DS, Avigo R, Boretzky K, Bracco A, Caesar C, Camera F, Chen S, Derya V, Doornenbal P, Endres J, Fukuda N, Garg U, Giaz A, Harakeh MN, Heil M, Horvat A, Ieki K, Imai N, Inabe N, Kalantar-Nayestanaki N, Kobayashi N, Kondo Y, Koyama S, Kubo T, Martel I, Matsushita M, Million B, Motobayashi T, Nakamura T, Nakatsuka N, Nishimura M, Nishimura S, Ota S, Otsu H, Ozaki T, Petri M, Reifarth R, Rodríguez-Sánchez JL, Rossi D, Saito AT, Sakurai H, Savran D, Scheit H, Schindler F, Schrock P, Semmler D, Shiga Y, Shikata M, Shimizu Y, Simon H, Steppenbeck D, Suzuki H, Sumikama T, Symochko D, Syndikus I, Takeda H, Takeuchi S, Taniuchi R, Togano Y, Tsubota J, Wang H, Wieland O, Yoneda K, Zenihiro J, and Zilges A

Abstract

Spectroscopic factors of neutron-hole and proton-hole states in ^{131}Sn and ^{131}In, respectively, were measured using one-nucleon removal reactions from doubly magic ^{132}Sn at relativistic energies. For ^{131}In, a 2910(50)-keV γ ray was observed for the first time and tentatively assigned to a decay from a 5/2^{-} state at 3275(50) keV to the known 1/2^{-} level at 365 keV. The spectroscopic factors determined for this new excited state and three other single-hole states provide first evidence for a strong fragmentation of single-hole strength in ^{131}Sn and ^{131}In. The experimental results are compared to theoretical calculations based on the relativistic particle-vibration coupling model and to experimental information for single-hole states in the stable doubly magic nucleus ^{208}Pb.

Published
2020
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