scholarly journals Exotic structures in exotic nuclei

2020 ◽  
Author(s):  
Francisco Miguel Marqués
Keyword(s):  
Hydrogen Isotopes ◽  
Exotic Nuclei ◽  
Neutron Halo ◽  
Light Elements ◽  
Nuclear Models ◽  
Neutron Dripline

Nuclei with proton and neutron numbers away from stability are known as exotic, and provide stringent tests of nuclear models, mainly developed for the description of stable nuclei. However, only the most extreme combinations lead to literally exotic structures, with sometimes unexpected properties. In this contribution we review some selected examples around the neutron dripline of very light elements: neutron halo structures with embedded substructures in the boron chain; the emission of neutron pairs in ^{16}16Be; and the existence of multi-neutron resonances in ‘superheavy’ hydrogen isotopes.

scholarly journals Synthesis reactions of neutron-rich isotopes of light elements

2021 ◽  
Vol 5 (2) ◽  
pp. 70-87
Author(s):  
Yu.E. Penionzhkevich
Keyword(s):  
Binding Energy ◽  
Nuclear Physics ◽  
Heavy Ion ◽  
Exotic Nuclei ◽  
Light Elements ◽  
Short Lifetime ◽  
Direct Reactions ◽  
Experimental Nuclear Physics ◽  
Neutron Rich Isotopes ◽  
Synthesis Reactions

One of the most complicated problems of experimental nuclear physics is the synthesis of exotic nuclei near the boundaries of stability. These nuclei, as a rule, are 10 or more neutrons away from stable nuclei, have a short lifetime (less than 1 ms) and low binding energy. All this determines special requirements to the choice of reactions for the synthesis of such nuclei and the method of their transportation and registration. Mainly, for the synthesis of exotic nuclei, reactions of fragmentation of the bombarding heavy ion, direct reactions of the types (p, d) , (d, p) , (d, n) , ( d , 3 He), etc., as well as reactions of fission and deep inelastic transfer are used.

scholarly journals Structure of superheavy hydrogen 7H

2020 ◽  
Vol 232 ◽  
pp. 04002
Author(s):  
M. Caamaño ◽  
T. Roger ◽  
A. M. Moro ◽  
G. F. Grinyer ◽  
J. Pancin ◽  
...  
Keyword(s):  
Ground State ◽  
Half Life ◽  
Neutron Emission ◽  
Theoretical Models ◽  
Neutron Halo ◽  
Nuclear System ◽  
Nuclear Forces ◽  
Nuclear Models ◽  
Basic Characteristics ◽  
New Phenomena

The properties of nuclei with extreme neutron–to–proton ratios reveal the limitations of state-ofthe-art nuclear models and are key to understand nuclear forces. 7H, with six neutrons and a single proton, is the nuclear system with the most unbalanced neutron–to–proton ratio ever known, but its sheer existence and properties are still a challenge for experimental efforts and theoretical models. We report here the first measurement of the basic characteristics and structure of the ground state of 7H; they depict a system with a triton core surrounded by an extended four-neutron halo, built by neutron pairing, that decays through a unique four–neutron emission with a relatively long half-life. These properties are a prime example of new phenomena occurring in almost pure-neutron nuclear matter, beyond the binding limits of the nuclear landscape, that are yet to be described within our current models.

scholarly journals CHARGE DENSITY DISTRIBUTIONS AND RELATED FORM FACTORS IN NEUTRON-RICH LIGHT EXOTIC NUCLEI

2004 ◽  
Vol 13 (04) ◽  
pp. 759-772 ◽  
Author(s):  
A. N. ANTONOV ◽  
M. K. GAIDAROV ◽  
D. N. KADREV ◽  
P. E. HODGSON ◽  
E. MOYA DE GUERRA
Keyword(s):  
Charge Density ◽  
Storage Ring ◽  
Exotic Nucleus ◽  
Form Factors ◽  
Theoretical Models ◽  
Exotic Nuclei ◽  
Proton Density ◽  
Neutron Halo ◽  
Related Form ◽  
Density Distributions

Charge form factors corresponding to proton density distributions in exotic nuclei, such as 6,8 He , 11 Li , 17,19 B and 14 Be are calculated and compared. The results can be used as tests of various theoretical models for the exotic nuclei structure in possible future experiments using a colliding electron-exotic nucleus storage ring. The result of such a comparison would show the effect of the neutron halo or skin on the proton distributions in exotic nuclei.

Structure of Two-Neutron Halo in Light Exotic Nuclei

2021 ◽  
Vol 62 (3) ◽  
Author(s):  
Toshio Suzuki ◽  
Takaharu Otsuka
Keyword(s):  
Exotic Nuclei ◽  
Neutron Halo

Scattering-angle dependence of signal/background ratio of inner-shell electron excitation loss in EELS

1983 ◽  
Vol 41 ◽  
pp. 390-391
Author(s):  
T. Oikawa ◽  
M. Inoue ◽  
T. Honda ◽  
Y. Kokubo
Keyword(s):  
Energy Loss ◽  
Electron Excitation ◽  
Heavy Elements ◽  
Background Intensity ◽  
Light Elements ◽  
Energy Analyzer ◽  
High Background ◽  
Scattering Angle ◽  
Angle Dependence ◽  
Shell Electron

EELS allows us to make analysis of light elements such as hydrogen to heavy elements of microareas on the specimen. In energy loss spectra, however, elemental signals ride on a high background; therefore, the signal/background (S/B) ratio is very low in EELS. A technique which collects the center beam axial-symmetrically in the scattering angle is generally used to obtain high total intensity. However, the technique collects high background intensity together with elemental signals; therefore, the technique does not improve the S/B ratio. This report presents the experimental results of the S/B ratio measured as a function of the scattering angle and shows the possibility of the S/B ratio being improved in the high scattering angle range.Energy loss spectra have been measured using a JEM-200CX TEM with an energy analyzer ASEA3 at 200 kV.Fig.l shows a typical K-shell electron excitation edge riding on background in an energy loss spectrum.

Quantitative EPMA of nitrogen : A tricky element in the electron-probe microanalyzer

1992 ◽  
Vol 50 (2) ◽  
pp. 1622-1623
Author(s):  
G.F. Bastin ◽  
H.J.M. Heijligers
Keyword(s):  
Background Subtraction ◽  
Electron Probe ◽  
Detection System ◽  
Higher Order ◽  
Light Elements ◽  
Strong Suppression ◽  
Electron Probe Microanalyzer ◽  
Quantitative Epma ◽  
Peak Count ◽  
Lead Stearate

Among the ultra-light elements B, C, N, and O nitrogen is the most difficult element to deal with in the electron probe microanalyzer. This is mainly caused by the severe absorption that N-Kα radiation suffers in carbon which is abundantly present in the detection system (lead-stearate crystal, carbonaceous counter window). As a result the peak-to-background ratios for N-Kα measured with a conventional lead-stearate crystal can attain values well below unity in many binary nitrides . An additional complication can be caused by the presence of interfering higher-order reflections from the metal partner in the nitride specimen; notorious examples are elements such as Zr and Nb. In nitrides containing these elements is is virtually impossible to carry out an accurate background subtraction which becomes increasingly important with lower and lower peak-to-background ratios. The use of a synthetic multilayer crystal such as W/Si (2d-spacing 59.8 Å) can bring significant improvements in terms of both higher peak count rates as well as a strong suppression of higher-order reflections.

Utilization of the nuclear energy of the light elements

1991 ◽  
Vol 161 (5) ◽  
pp. 171-175 ◽  
Author(s):  
Yu.B. Khariton ◽  
Ya.B. Zeldovich ◽  
I.I. Gurevich ◽  
I.Ya. Pomeranchuk
Keyword(s):  
Nuclear Energy ◽  
Light Elements
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