NOTAS DE FÍSICA
https://revistas.cbpf.br/index.php/NF
<p><strong>ISSN:</strong> 2318-4957 (Online)<br /><strong>ISSN:</strong> 0029-3865 (Impresso)<br /><strong>DOI:</strong> <a href="https://dx.doi.org/10.7437/NF2318-4957" target="_blank" rel="noopener">dx.doi.org/10.7437/NF2318-4957</a></p> <p><strong>ANO DE INÍCIO:</strong> 1952</p>CBPFpt-BRNOTAS DE FÍSICA0029-3865Nonlocality Effect in Alpha Decay of Heavy and Superheavy Nuclei
https://revistas.cbpf.br/index.php/NF/article/view/221
<p>Alpha decay half-life of heavy and superheavy nuclei has been investigated using a potential barrier penetration model that adapts semiclassical WKB calculations to incorporate a coordinate-dependent effective mass for the alpha particle. This effect is a consequence of a dynamic property of nonlocality in the particle-nucleus interaction, as implemented in the barrier tunneling calculations of Ref. [1]. Calculations have been performed for a recent set of experimental data of 255 alpha-emitting nuclides, all selected with angular momentum $\ell = 0$ experimentally assigned. Results show a good agreement when compared to experimental half-life data, obtaining a standard deviation $\sigma=0.306$, and fully satisfying the universal NUP and UDL systematics of alpha decay. Additionally, the present model has been applied to make half-life predictions for thirty-four possible, new alpha decay cases.</p>Emil L. MedeirosN. TeruyaSérgio B. DuarteO. A. P. Tavares
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2022-04-102022-04-101-3The Periodic Table of the Elements
https://revistas.cbpf.br/index.php/NF/article/view/219
<div>The Periodic Table of Mendeleev, initially proposed on the basis of 66 elements, and containing 82 elements at the time of Moseley (1887−1915), describes nowadays 118 elements. The huge challenge of this scientific adventure was, and still is, the development of technologies and methods capable of producing elements of atomic number Z > 103, known as superheavy elements (SHE), or transactinides. This paper presents a survey of experiments and theoretical approaches that led physicists and chemists of today to discover and characterize a number of SHE isotopes. A glance is also given to the feasibility studies performed by scientists aiming to going beyond Z = 118, building-up further neutron-rich nuclides and reaching the ultimate goal of creating long-living new elements at the edge of the Table.</div>Maria TerranovaOdilon A. P. Tavares
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2022-04-102022-04-101-3First quantization of braided Majorana fermions
https://revistas.cbpf.br/index.php/NF/article/view/220
<p>A Z2-graded qubit represents an even (bosonic) “vacuum state” and an odd, excited,<br>Majorana fermion state. The multiparticle sectors of N, braided, indistinguishable Majorana fermions are constructed via first quantization. The framework is that of a graded<br>Hopf algebra endowed with a braided tensor product. The Hopf algebra is U(gl(1|1)), the<br>Universal Enveloping Algebra of the gl(1|1) superalgebra. A 4×4 braiding matrix Bt defines<br>the braided tensor product. Bt, which is related to the R-matrix of the Alexander-Conway<br>polynomial, depends on the braiding parameter t belonging to the punctured plane (t ∈ C<br>∗<br>);<br>the ordinary antisymmetry property of fermions is recovered for t = 1.<br>For each N, the graded dimension m|n of the graded multiparticle Hilbert space is computed.<br>Besides the generic case, truncations occur when t coincides with certain roots of unity which<br>appear as solutions of an ordered set of polynomial equations. The roots of unity are organized into levels which specify the maximal number of allowed braided Majorana fermions<br>in a multiparticle sector.<br>By taking into account that the even/odd sectors in a Z2-graded Hilbert space are superselected, a nontrivial braiding with t 6= 1 is essential to produce a nontrivial Hilbert space<br>described by qubits, qutrits, etc., since at t = 1 the N-particle vacuum and the antisymmetrized excited state encode the same information carried by a classical $1$-bit.</p>Francesco Toppan
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2022-04-102022-04-101-3