Effective proton-neutron interaction near the drip line from unbound states in F-25,F-26
Effective proton-neutron interaction near the drip line from unbound states in F-25,F-26
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F-25、F-26 中未结合态滴线附近的有效质子-中子相互作用
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
K. Zuber
中科院分区：
文献类型：
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作者：
M. Vandebrouck;A. Lepailleur;O. Sorlin;T. Aumann;C. Caesar;M. Holl;V. Panin;F. Wamers;Steven Ragnar Stroberg;J. Holt;F. Santos;H. Alvarez;L. Atar;V. Avdeichikov;S. Beceiro;D. Bemmerer;J. Benlliure;C. Bertulani;S. Bogner;J. M. Boillos;K. Boretzky;M. Borge;M. Caamano;E. Casarejos;W. Catford;J. Cederkall;M. Chartier;L. Chulkov;D. Cortina;E. Cravo;R. Crespo;U. D. Pramanik;P. D. Fernandez;I. Dillmann;Z. Elekes;J. Enders;O. Ershova;A. Estrade;F. Farinon;L. Fraile;M. Freer;D. Galaviz;H. Geissel;R. Gernhauser;J. Gibelin;P. Golubev;K. Gobel;J. Hagdahl;T. Heftrich;M. Heil;M. Heine;A. Heinz;A. Henriques;H. Hergert;A. Hufnagel;A. Ignatov;H. Johansson;B. Jonson;J. Kahlbow;N. Kalantar;R. Kanungo;A. Kelić;A. Knyazev;T. Kroll;N. Kurz;M. Labiche;C. Langer;T. Bleis;R. Lemmon;S. Lindberg;J. Machado;J. Marganiec;F. M. Marques;A. Movsesyan;E. Nácher;M. Najafi;E. Nikolskii;T. Nilsson;C. Nociforo;S. Paschalis;A. Perea;M. Petri;S. Pietri;R. Plag;R. Reifarth;G. Ribeiro;C. Rigollet;M. Roder;D. Rossi;D. Savran;H. Scheit;A. Schwenk;H. Simon;I. Syndikus;J. Taylor;O. Tengblad;R. Thies;Y. Togano;P. Velho;V. Volkov;A. Wagner;H. Weick;C. Wheldon;G. Wilson;J. Winfield;P. Woods;D. Yakorev;M. Zhukov;A. Zilges;K. Zuber
背景：围绕双闭合壳层的奇核已被广泛用于研究质子-中子相互作用。然而，这些相互作用作为结合能的函数的演变，最终当原子核变得没有结合时，却鲜为人知。F-26核由一个深束缚的pI0d(5/2)质子和一个非束缚的v0d(3/2)中子组成，位于O-24核的顶部，特别适合于这一目的。这种质子与中子的耦合产生了J(Pi)=1(1)(+)-4(1)(+)多重态，为了研究连续体的邻近对相应的质子-中子相互作用的影响，必须确定它的能量。J(Pi)=1(1)(+)，2(1)(+)，4(1)(+)束缚态已经确定，只缺少J(Pi)=3(1)(+)的明确识别。目的：通过研究J(Pi)=3(1)(+)非束缚态的能量和宽度，完成对F-26中J(Pi)=1(1)(+)-4(1)(+)多重态的研究。该方法首先通过对F-25中非束缚态的研究来验证，在先前的实验中已经观察到了这些态的共振。方法：用GSI装置的碎片分离器在约440AMeV产生的Ne-26和Ne-27放射束，通过位于(RB)-B-3/LAND装置的目标焦点的CH2靶上的单质子敲除反应，填充F-25和F-26的非结合态。对发射物的检测。在重建A-1核动量矢量的过程中加入射线和中子，就可以确定F-25和F-26的三个非束缚态和两个非束缚态的能量。结果：根据F-25的宽度和衰变性质，提出在相对能量为49(9)keV时，F-25中的第一个非束缚态是由p1/2质子空穴态产生的J(Pi)=1/2(-)。在F-26中，323(33)keV处的第一个共振被认为是J(Pi)=1(1)(+)-4(1)(+)多重态的J(Pi)=3(1)(+)成员。用独立粒子壳层模型、唯象壳层模型和从头算价空间介质相似重整化群方法，比较了F-25、F-26的观察态能量。结论：与模型相比，推导出的有效质子-中子相互作用减弱了约30%-40%，这表明需要在理论描述中实现连续统的作用，或者是对F-26原子质量的错误确定。
Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The F-26 nucleus, composed of a deeply bound pi 0d(5/2) proton and an unbound v0d(3/2) neutron on top of an O-24 core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a J(pi) = 1(1)(+) - 4(1)(+) multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The J(pi) = 1(1)(+), 2(1)(+), 4(1)(+) bound states have been determined, and only a clear identification of the J(pi) = 3(1)(+) is missing. Purpose: We wish to complete the study of the J(pi) = 1(1)(+) - 4(1)(+) multiplet in F-26, by studying the energy and width of the J(pi) = 3(1)(+) unbound state. The method was first validated by the study of unbound states in F-25, for which resonances were already observed in a previous experiment. Method: Radioactive beams of Ne-26 and Ne-27, produced at about 440AMeV by the fragment separator at the GSI facility were used to populate unbound states in F-25 and F-26 via one-proton knockout reactions on a CH2 target, located at the object focal point of the (RB)-B-3/LAND setup. The detection of emitted. rays and neutrons, added to the reconstruction of the momentum vector of the A - 1 nuclei, allowed the determination of the energy of three unbound states in F-25 and two in F-26. Results: Based on its width and decay properties, the first unbound state in F-25, at the relative energy of 49(9) keV, is proposed to be a J(pi) = 1/ 2(-) arising from a p1/2 proton- hole state. In F-26, the first resonance at 323(33) keV is proposed to be the J(pi) = 3(1)(+) member of the J(pi) = 1(1)(+) - 4(1)(+) multiplet. Energies of observed states in F-25,F-26 have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton- neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of F-26.