The European Physical Journal A最新文献

Nuclear physics experiments often involve complex geometrical configurations and intricate de-excitation schemes. Combined (gamma )-ray and conversion-electron spectroscopy experiments are prime examples. The design of the required instrumentation and the interpretation of the resulting data can greatly benefit from detailed simulations. Here, we report on extensions to the NPTool framework that enable an accurate representation of the experimental conditions associated with the sage and spede spectrometers. In addition, we introduce a program package for implementing complicated de-excitation patterns to complement the NPTool framework.

The transuranic-transfermium region ((Z ge 92)) hosts 221 known isomers across 160 isotopes. We examine their single-particle configurations and (alpha )-decay stability relative to ground states. Our analysis reveals that proton or neutron shell/subshell closures enhance isomer production and stabilize high-spin multi-quasiparticle configurations by strengthening couplings between complementary valence nucleons. Evidenced deformed sub-shell closure at (Z=96) [(Z=104)] boosts isomer yields attributed to occupations in (pi 5/2^+[642](1i_{13/2^+})), (pi 5/2^-[523](1h_{9/2^-})) and (pi 7/2^+[633](1i_{13/2^+})) [(pi 9/2^+[624](1i_{13/2^+})), (pi 1/2^-[521] (2f_{5/2^-})) and (pi 7/2^-[514](1h_{9/2^-}))] orbitals. A neutron deformed shell gap at (N=152) promotes isomerism in (N=151,153) isotones, primarily through (nu 5/2^+[622](1i_{11/2^+})), (nu 11/2^-[725](1j_{15/2^-})), and (nu 9/2^-[734](1j_{15/2^-})) excitations. The leading quasi-particle configurations in the isomers of (N=147)–149 isotones originate from neutrons/holes in the (nu 7/2^+[624](2g_{9/2^+})) and (nu 1/2^+[631] (3d_{5/2^+})) orbitals. The most stable isomers are predominantly driven by excitations in the (pi 1i_{13/2^+}) and (nu 1j_{15/2^-}) orbitals, under moderate prolate deformation, with key contributions from the (pi 11/2^+[615]), (pi 9/2^+[624]), (pi 7/2^+[633]), (pi 5/2^+[642]), (nu 11/2^-[725]), (nu 9/2^-[734]), and (nu 7/2^-[743]) states, then from deformed states of the (pi 2f_{7/2^-}) and (nu 1i_{11/2^+}) orbitals. Unlike heavier transfermiums, isomers (iso) of the Np–Es isotopes ((N=127)–144 isotones) exhibit no (alpha )-decays. The limited data constrain (log _{10} T_{alpha }^{text {(iso)}}) to a single linear trend versus (sqrt{Q_{alpha }^{-1}}) for favored and unfavored decays, unlike the ground-state decays where the trend’s slope correlates with the transferred angular momentum ((Delta l)), with stability enhanced against high-(Delta l) decays. The (alpha )-preformation factor in isomers (S_{alpha }^{text {(iso)}}) exceeds ground-state (gs) value only when (Q_{alpha }^{text {(iso)}} le Q_{alpha }^{text {(gs)}}) and (Delta l) is low; otherwise, (S_{alpha }^{text {(iso)}}) drops by 1–3 orders of magnitude, decreasing with both (Q_{alpha }^{text {(iso)}}) and (Delta l). This study reveals transactinide isomers as a promising research direction for finding stable configurations in undiscovered superheavy nuclei.

Investigating giant resonances is essential for deepening our understanding of nuclear structure and constraining the nuclear matter equation of state. In this work, we explore both giant dipole and quadrupole resonances in the superfluid nucleus (^{112})Sn based on a fully self-consistent quasiparticle-vibration coupling (QPVC) theory with the Skyrme interaction. Incorporating QPVC effects refines the description of the isoscalar and isovector modes by producing a downward energy shift and a broader width that are more consistent with experimental observations. Based on quasiparticle random phase approximation (QRPA) and QPVC model, the photoabsorption cross sections are further studied. It is shown that plane-wave (gamma )-photons predominantly excite the electric dipole (E1) mode. In contrast, when the nucleus aligns with the beam, vortex (gamma )-photons selectively excite the transition with a certain multipolarity through new selection rules given by angular momentum conservation. When the nucleus is offset from the beam axis, angular momentum selection rules relax, allowing the (E1) component to gradually recover and supplant the electric quadrupole or octupole transitions, while the oscillatory behavior of the Bessel functions governs fluctuations in the (E1) cross section. By comparing QRPA and QPVC results, QPVC shows its effect in the high energy range of vortex photon absorption cross sections at small impact parameters.

New experimental values for the (gamma )-ray emission intensities in the decay of (^text {235})U have been obtained by measurements of a 230-g certified triuranium octoxide sample enriched in (^text {235})U to 93.2% with a 70 cm(^{text {3}}) high-purity germanium detector over 1111 h. Calibration of energy scale and detection efficiency was performed by using peaks of (^text {235})U, (^text {234m})Pa, and U/Th series daughters. The revised intensities account for cascade summation, random coincidences, and interference from (gamma )-rays of other nuclides. Intensities of several (gamma ) transitions were found to have been significantly overestimated in earlier studies, by up to two orders of magnitude.

We introduce a new scheme for quantum circuit design called controlled gate networks. Rather than trying to reduce the complexity of individual unitary operations, the new strategy is to toggle between all of the unitary operations needed with the fewest number of gates. We present the general theory of controlled gate networks and show that, under quite general conditions, it can significantly reduce the number of two-qubit gates needed to produce linear combinations of unitary operators. The first example we consider is a variational subspace calculation for a two-qubit system. The second example is estimating the eigenvalues of a two-qubit Hamiltonian via the rodeo algorithm (Choi et al. in Phys Rev Lett 127(4):040505, 2021. https://doi.org/10.1103/PhysRevLett.127.040505) using operators that we call controlled reversal gates. We use the Quantinuum H1-2 and IBM Perth devices to realize the quantum circuits. The third example is the application of controlled gate networks to the controlled time evolution of a free nucleon on a three-dimensional lattice. For all of the examples, we show very substantial reductions in the number of two-qubit gates required. Our work demonstrates that controlled gate networks are a useful tool for reducing gate complexity in quantum algorithms for quantum many-body problems such as those relevant to nuclear physics.

In this study, we investigate the half-lives of the allowed combined (beta ^+) and electron-capture ((beta ^+)/EC) decays of nuclei with (Z = 31{-}40) and (A = 60{-}89) employing shell-model calculations within the (f_{5/2}pg_{9/2}) valence space using the JUN45 interaction. Using the quenching factor (q=0.71pm 0.01) for the weak axial coupling (g_A,) obtained from the analysis of pure Gamow–Teller (beta ^{-}) and (beta ^{+}) decay processes in nuclei with (Z = 31 {-} 40) and (A = 61{-}87,) the transition strengths and branching ratios for the (beta ^{+})/EC decays are evaluated. The experimental (beta )-decay half-lives are found to be rather well explained by the shell-model calculations. We investigate also the isospin mixing in the ground states of (^{64})Ge, (^{70})Se, and (^{78})Rb nuclei for non-analog (0^+ rightarrow 0^+) ((varDelta Tne 0)) (beta ) transitions from (^{64})Ge, (^{70})Se, and (^{78})Rb. A comprehensive study of the (beta ^{+})/EC-decay processes in nuclei in this region is done for the first time in the present work. Though the model space has a limitation due to the lack of its (f_{7/2}) and (g_{7/2}) spin-orbit partners, the results obtained can be considered reasonable.

Nuclear resonances provide a rich and versatile testbed for exploring fundamental aspects of physics, particularly within the domain of strongly correlated many-body systems. The overarching goal of the theory is to develop a consistent and predictive framework that is (i) capable of a spectroscopically accurate description and (ii) sufficiently general to be applied across different energy scales and transferable to a wide range of complex systems. Thoroughly capturing emergent collective phenomena that arise in nuclear media is the central challenge for the theory, which is discussed in this contribution. It concentrates on the themes inspired and influenced by Angela Bracco’s research, in particular, on the fragmentation patterns of the monopole and dipole responses of medium-heavy nuclei and associated open problems.

This study derives the relativistic transformations of thermodynamic quantities from the Lorentz transformations applied to the four-momentum components of a thermodynamic system, which is stationary in the inertial reference frame ( K_0 ) and moves at constant velocity relative to the laboratory frame K. Thermodynamic variables are introduced into the formalism via the zeroth component of the four-momentum in ( K_0 ), representing the system’s internal energy. Entropy and particle number are relativistic invariants, while the volume undergoes Lorentz contraction. By treating the three-momentum as an independent state variable, thermodynamic quantities are defined by differentiating the zeroth component of the four-momentum (the Hamiltonian) in the reference frame K with respect to the independent state variables, yielding the fundamental thermodynamic potential. This approach results in the Non-Planck transformations, which differ from the Planck transformations by a factor of ( alpha ). In contrast, by adopting the three-velocity as an independent state variable, thermodynamic quantities are obtained by differentiating the negative Lagrangian, derived from the zeroth component of the four-momentum via Legendre transformations, with respect to the independent state variables, producing the conjugate fundamental thermodynamic potential. This yields the Planck transformations. Conversely, the Ott transformations are derived from the zeroth component of the four-momentum by treating velocity as an independent state variable. This approach conflicts with the principles of mechanics, resulting in an energy that does not qualify as a thermodynamic potential. To validate these findings, we analyze an ultrarelativistic ideal gas of quarks and gluons within the Stefan–Boltzmann limit. Furthermore, we develop consistent Boltzmann–Gibbs and Tsallis blast-wave models for finite-volume freeze-out firecylinders in heavy ion collisions, incorporating Planck and Ott transformations. Comparative analysis demonstrates that Planck transformations yield consistent transverse momentum distributions of hadrons, whereas Ott transformations result in discrepancies.

This paper is in memory of Roberto Gallino, a long-time collaborator on questions of neutron sources and neutron-induced reactions in stellar nucleosynthesis. We therefore discuss a topic that was of great interest to him, the correlation between neutron sources that provide the neutron flux for the production of heavy elements in the s-process and neutron poison reactions that reduce the number of neutrons in the stellar environment. Neutron poisons play a role in all s-process environments, such as the final phase of core helium burning of massive stars or the carbon pocket in hydrogen-helium intershell environment of low-mass AGB stars, originally proposed by Gallino and his co-workers more than 40 years ago. This paper will argue that neutron poison reactions serve as a neutron storage mechanism through which neutron sources can be fueled to provide a delayed neutron release.

Enhanced unified empirical formulas for both (alpha )- and cluster decay half-lives have been developed by incorporating the effects of angular momentum, isospin asymmetry, and, most importantly, the deformation of daughter nuclei. The updated coefficients were determined using the latest experimental data for (alpha )-decay half-lives of 573 nuclei in the range (52< Z < 118), together with 21 available cluster decay half-lives. To model the impact of deformation, two additional terms – dependent on the quadrupole and hexadecapole deformation parameters – were introduced. Our analysis shows that the quadrupole deformation parameter ((beta _2)) significantly improves agreement with experiment, while the hexadecapole deformation parameter ((beta _4)) produces only marginal effects. These revised empirical formulas yield predictions for both (alpha )- and cluster decay half-lives that are in strong agreement with other similar calculations and have been validated through comparisons with recent experimental results and theoretical predictions. Furthermore, the new formulas were applied to estimate the half-lives of cluster emissions from superheavy nuclei with (Z=120), 122, 124, and 126, and the variation of (log _{10} T_alpha ) with changes in neutron number was thoroughly explored.