Ground State Masses Research Articles

Calculations of the cross sections for the synthesis of new293–296118 isotopes in249–252Cf(48Ca,xn) reactions

A project of using a target consisting of the mixture of (249-252)Cf isotopes to be bombarded with the 48Ca beam, aimed to synthesize new isotopes of the heaviest known element Z = 118, is under way at the FLNR in Dubna. In the present work excitation functions for all the reactions: 249Cf(48Ca,xn)(297-x)118, 250Cf(48Ca,xn)(298-x)118, 251Cf(48Ca,xn)(299-x)118 and 252Cf(48Ca,xn)(300-x)118 have been calculated in the framework of the fusion-by-diffusion model, assuming fission barriers, ground-state masses and shell effects of the superheavy nuclei predicted by Kowal et al. Energy dependence of the effective cross sections for the synthesis of selected new isotopes: (293)118, (294)118, (295)118 and (296)118 is predicted for the particular isotopic composition of the Cf target prepared for the Dubna experiment.

Calculations of synthesis cross sections of Z = 104–113 superheavy nuclei in the fusion-by-diffusion model with the Warsaw macro–micro-model fission barriers

The results of experiments carried out at GSI Darmstadt, LBNL Berkeley and RIKEN Tokyo on the synthesis of superheavy nuclei of Z = 104–113 in cold fusion reactions have been analyzed within the fusion-by-diffusion (FBD) model by using the fission barriers, ground-state masses, shell effects and deformations calculated with the Warsaw macroscopic–microscopic model. An empirical parametrization of the injection-point distance has been established for this new theoretical input to the FBD model that enables one to reproduce existing data with reasonable accuracy and predict synthesis cross sections and optimum bombarding energies in as yet unexplored cold fusion reactions.

Masses and rotational energies of the heaviest nuclei

The ground-state masses of even–even 226Ra–278Cn isotopes are obtained within the macroscopic–microscopic model using the Lublin Strasbourg drop mass formula for the macroscopic part and the Yukawa-folded single-particle potential to evaluate the microscopic energy corrections. The pairing correlations are included within the Bardeen–Cooper–Schrieffer formalism with an approximated particle number projection. The coupling of the rotation with the pairing field is taken into account when evaluating the energies of the ground-state rotational band.

Potential energy landscapes of Th isotopes within the Lublin Strasbourg drop + Yukawa-folded model

Advanced calculations of potential energy surfaces in a four-dimensional deformation space were performed for even–even Th isotopes using the macroscopic–microscopic method. The macroscopic part of the total energy was derived from the Lublin Strasbourg drop model. The Yukawa-folded potential was used to generate the single-particle spectra. The asymptotic Strutinsky shell-correction method and the Bardeen–Cooper–Schrieffer theory with approximate particle number projection were used to evaluate the microscopic part of the nuclear energy. Predictions for the ground-state masses and fission-barrier heights agree well with the experimental data. An accurate analysis of the computed multi-dimensional energy maps is in progress. Our preliminary results indicate that the present approach is capable of addressing the evolution of fission modality in the actinide region.

Prospects for hypernuclear physics at Mainz: From KAOS@MAMI to PANDA@FAIR

Abstract At the Mainz Microtron hypernuclei are produced by ( e , e ′ K ) reactions. A dedicated kaon spectrometer located at 0° with respect to the electron beam is used to detect kaons emitted in forward direction thus tagging events involving strangeness production. By measuring the momenta of pions from two body weak decays using high resolution magnetic spectrometers one gains direct access to the ground state masses of the produced hyperfragments. At FAIR the PANDA Collaboration intends to produce double-hypernuclei by numbers with an antiproton beam and study their high resolution γ -spectroscopy thus providing for the first time precise information on the level structure of these nuclei. The status of both experiments is reviewed.

A Laplace Sum-Rules Analysis of Heavy Pseudoscalar ([formula omitted]) Hybrids

We use QCD sum-rules to predict ground state masses for pseudoscalar (JPC=0−+) charmonium and bottomonium hybrids. We find that the inclusion of a six-dimensional gluon condensate contribution is needed to stabilize the analyses. For the charmonium hybrid, we find a mass of (3.82 ± 0.13) GeV; for the bottomonium hybrid, we find a mass of (10.64 ± 0.19) GeV. We comment on possible phenomenological implications concerning the Y(3940).

The Schwarzschild black hole’s remnant via the Bohr-Sommerfeld quantization rule

A d-dimensional Schwarzschild black hole is quantized by the action variable and the Bohr-Sommerfeld quantization rule in this paper. We find that the spectra of the horizon area and the entropy are evenly spaced. The black hole mass is also quantized and it’s spectrum spacing is proportional inversely to the mass. The ground state appears and has a constant entropy \(\pi k_B\). The ground state mass is shown to be the black hole remnant predicted by the generalized uncertainty principle and may be a candidate of dark matter.

Octet baryon masses in next-to-next-to-next-to-leading order covariant baryon chiral perturbation theory

We study the ground-state octet baryon masses and sigma terms using the covariant baryon chiral perturbation theory (ChPT) with the extended-on-mass-shell (EOMS) renormalization scheme up to next-to-next-to-next-to-leading order (N3LO). By adjusting the available 19 low-energy constants (LECs), a reasonable fit of the n f = 2+1 lattice quantum chromodynamics (LQCD) results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD and NPLQCD collaborations is achieved. Finite-volume corrections to the lattice data are calculated self-consistently. Our study shows that the N3LO BChPT describes better the light quark mass evolution of the lattice data than the NNLO BChPT does and the various lattice simulations seem to be consistent with each other. We also predict the pion and strangeness sigma terms of the octet baryons using the LECs determined in the fit of their masses. The predicted pion- and strangeness-nucleon sigma terms are σ πN = 43(1)(6) MeV and σ sN = 126(24)(54) MeV, respectively.

CURVATURE INTERACTION IN COLLECTIVE SPACE

For the Riemannian space, built from the collective coordinates used within nuclear models, an additional interaction with the metric is investigated, using the collective equivalent to Einstein's curvature scalar. The coupling strength is determined using a fit with the AME2003 ground state masses. An extended finite-range droplet model including curvature is introduced, which generates significant improvements for light nuclei and nuclei in the trans-fermium region.

Single charm and beauty baryon masses in the hypercentral approach

Heavy flavour baryons containing one charm (beauty) quark with light flavour combinations are studied using the hypercentral approach. The considered potential is a combination of Coulombic, linear confining and harmonic oscillator terms. An improved form of the hyperfine interaction and isospin-dependent quark potential is introduced. The ground-state masses ( \( J^p=1/2^+\) and \( 3/2^+\) of heavy baryons are computed. Also the magnetic moments of heavy baryons with \( J^p=3/2^+\) using the effective mass of the confined quarks are computed. The obtained results are close to the ones obtained in experiments or in the other works.

Systematic study of decay properties of heaviest elements

Decay properties and stability of heaviest nuclei with Z ≤ 132 are studied within the macro-microscopical approach for nuclear ground-state masses. We use phenomenological relations for the half-lives with respect to α-decay, β-decay and spontaneous fission. Our calculations demonstrate that the β-stable isotopes 291Cn and 293Cn with a half-life of about 100 years are the longest-living superheavy nuclei located on the first island of stability. We found the second island of stability of superheavy nuclei in the region of Z ≈ 124 and N ≈ 198. It is separated from the “continent” by the “gulf” of short-living nuclei with half-lives shorted than 1 μs.

On the consistency of recent QCD lattice data of the baryon ground-state masses

In our recent analysis of lattice data of the BMW, LHPC and PACS-CS groups we determined a parameter set of the chiral Lagrangian that allows a simultaneous description of the baryon octet and decuplet masses as measured by those lattice groups. The results on the baryon spectrum of the HSC group were recovered accurately without their inclusion into our 6 parameter fit. We show that the same parameter set provides an accurate reproduction of the recent results of the QCDSF-UKQCD group probing the baryon masses at quite different quark masses. This shows a remarkable consistency amongst the different lattice simulations. With even more accurate lattice data in the near future it will become feasible to determine all low-energy parameters relevant at N$^3$LO.

The Translation Invariant Massive Nelson Model: II. The Continuous Spectrum below the Two-Boson Threshold

In this paper we continue the study of the energy-momentum spectrum of a class of translation invariant, linearly coupled, and massive Hamiltonians from non-relativistic quantum field theory. The class contains the Hamiltonians of E. Nelson and H. Froehlich. One of us previously investigated the structure of the ground state mass shell and the bottom of the continuous energy-momentum spectrum. Here we study the continuous energy-momentum spectrum itself up to the two-boson threshold, the threshold for energetic support of two-boson scattering states. We prove that non-threshold embedded mass shells have finite multiplicity and can accumulate only at thresholds. We furthermore establish the non-existence of singular continuous energy-momentum spectrum. Our results hold true for all values of the particle-field coupling strength but only below the two-boson threshold. The proof revolves around the construction of a certain relative velocity vector field used to construct a conjugate operator in the sense of Mourre.

Temperature-dependent cross sections for πφ and ρφ nonresonant reactions in hadronic matter

With a potential of which the large-distance part reflects lattice gauge results and of which the short-distance part is given by one gluon exchange plus perturbative one- and two-loop corrections, the Schrödinger equation brings about temperature dependence of meson masses and mesonic quark-antiquark relative-motion wave functions. The ground-state meson masses drop with increasing temperature. The transition amplitude calculated from the potential, the meson masses and the wave functions gives temperature-dependent cross sections for the five nonresonant reactions πφ → KK̄* (or K*K̄), ρφ → K*K̄*, ρφ → KK̄, ρφ → KK̄* (or K*K̄) and ρφ → K*K̄*. The numerical temperature-dependent cross sections are parametrized. The peak cross section of either πφ → KK̄* or πφ → K*K̄* increases from T = 0 to T = 0.75Tc and decreases with further increasing temperature. The cross section for ρφ → KK̄, ρφ → KK̄* or ρφ → K*K̄* has a decreasing trend while the temperature increases from 0.75Tc.

Two-proton decay of12O and its isobaric analog state in12N

Following neutron knockout from an ${}^{13}$O beam, ${}^{12}$O fragments were created and the three decay products following two-proton decay were detected. A new ground-state mass was determined by the invariant mass method implying a decay kinetic energy of 1.638(24) MeV, and the width was found to be less than 72 keV. The latter is inconsistent with previous measurements with lower experimental resolutions but consistent with theoretical estimates. The isobaric analog of ${}^{12}$O in ${}^{12}$N was produced from proton knockout reactions with the same beam and decayed by two-proton emission to the isobaric analog state in ${}^{10}$B with a decay kinetic energy of 1.165(29) MeV. It represents only the second case of an analog state where two-proton decay is the only isospin- and energy-conserving particle decay mode. With our measurements of the mass excesses of ${}^{12}$O and its analog, the quadratic form of the isobaric multiplet mass equation was found to fit the $A=12$ quintet and any deviations are less than the magnitude found for the $A=8$ quintet and $A=7$ and 9 quartets.

Gamow-Teller strengths and electron-capture rates forpf-shell nuclei of relevance for late stellar evolution

Background: Electron-capture reaction rates on medium-heavy nuclei are an important ingredient for modeling the late evolution of stars that become core-collapse or thermonuclear supernovae. The estimation of these rates requires the knowledge of Gamow-Teller strength distributions in the ${\ensuremath{\beta}}^{+}$ direction. Astrophysical models rely on electron-capture rate tables largely based on theoretical models, which must be validated and tested against experimental results.Purpose: This paper presents a systematic evaluation of the ability of theoretical models to reproduce experimental Gamow-Teller transition strength distributions measured via ($n$,$p$)-type charge-exchange reactions at intermediate beam energies. The focus is on transitions from stable nuclei in the $pf$ shell ($45\ensuremath{\le}A\ensuremath{\le}64$). In addition, the impact of deviations between experimental and theoretical Gamow-Teller strength distributions on derived stellar electron-capture rates is investigated.Method: Data on Gamow-Teller transitions from 13 nuclei in the $pf$ shell measured via charge-exchange reactions and supplemented with results from $\ensuremath{\beta}$-decay experiments where available, were compiled and compared with strength distributions calculated in shell models (using the GXPF1a and KB3G effective interactions) and quasiparticle random-phase approximation (QRPA) using ground-state deformation parameters and masses from the finite-range droplet model. Electron-capture rates at relevant stellar temperatures and densities were derived for all distributions and compared.Results: With few exceptions, shell-model calculations in the $pf$ model space with the KB3G and GXPF1a interactions qualitatively reproduce experimental Gamow-Teller strength distributions of 13 stable isotopes with $45\ensuremath{\le}A\ensuremath{\le}64$. Results from QRPA calculations exhibit much larger deviations from the data and overestimate the total experimental Gamow-Teller strengths. For stellar densities in excess of ${10}^{7}$ g/cm${}^{3}$, ground-state electron-capture rates derived from the shell-model calculations using the KB3G (GXPF1a) interaction deviate on average less than 47$%$ (31$%$) from those derived from experimental data for which the location of daughter states at low excitation energies are well established. For electron-capture rates derived from Gamow-Teller strengths calculated in QRPA, the deviations are much larger, especially at low stellar densities.Conclusions: Based on the limited set of test cases available for nuclei in the $pf$ shell, shell-models using the GXPF1a and KB3G interactions can be used to estimate electron-capture rates for astrophysical purposes with relatively good accuracy. Measures of the uncertainties in these rates can serve as input for sensitivity studies in stellar evolution models. Ground-state electron-capture rates based on the QRPA formalism discussed in the paper exhibit much larger deviations than those based on the shell-model calculations and should be used with caution, especially at low stellar densities.

Predictions of the fusion-by-diffusion model for the synthesis cross sections ofZ=114–120 elements based on macroscopic-microscopic fission barriers

A complete set of existing data on hot fusion reactions leading to synthesis of superheavy nuclei of Z =114-118, obtained in a series of experiments in Dubna and later in GSI Darmstadt and LBNL Berkeley, was analyzed in terms of a new angular-momentum dependent version of the Fusion by Diffusion (FBD) model with fission barriers and ground-state masses taken from the Warsaw macroscopic-microscopic model (involving non-axial shapes) of Kowal et al. The only empirically adjustable parameter of the model, the injection-point distance (sinj), has been determined individually for all the reactions and very regular systematics of this parameter have been established. The regularity of the obtained sinj systematics indirectly points at the internal consistency of the whole set of fission barriers used in the calculations. Having fitted all the experimental excitation functions for elements Z = 114-118, the FBD model (with the new sinj systematics) was used to predict cross sections for synthesis of elements Z = 119 and 120. Regarding prospects to produce the new element Z = 119, our calculations prefer the 252Es(48Ca,xn)300-x119 reaction, for which the synthesis cross section of about 0.2 pb in 4n channel at Ec.m.= 220 MeV is expected. The most favorable reaction to synthesize the element Z = 120 turns out to be 249Cf(50Ti,xn)299-x120, but the predicted cross section for this reaction is only 6 fb (for 3n and 4n channels).

Linking nuclear masses with nucleon-removal thresholds and the mass of the proton-emitter 17Na

We have surveyed known threshold excitations of mirror systems seeking systematic trends to predict masses of nuclear systems that are unmeasured. For the same purpose, we review mass equations for the ground states of isobaric multiplets. We use both methods to estimate the mass of the unmeasured 17Na ground state, as well as its energy gap to the p + 16Ne threshold. The results are discussed and compared to calculations performed recently in model-dependent studies.

MASSES OF CHARM AND BEAUTY BARYONS IN THE CONSTITUENT QUARK MODEL

The masses of the ground state heavy baryons are studied using the hypercentral approach. The considered potential is a combination of Coulombic, linear confining and harmonic oscillator terms. An improved form of the hyperfine interaction and isospin dependent quark potential is introduced. By solving the Schrödinger equation for three particles system, we calculate the ground state masses of the baryons containing one, two and three heavy quarks. The obtained results are very close to the ones obtained in experiments or in the other works.

Ground State Heavy Mesons Spectrum in Cornell Potential

This paper studies the meson masses containing heavy flavour quark (anti-quark) with light flavour combination. The considered potential is Coulomb as well as linear confining terms. Also, an improved form of the hyperfine interaction is introduced. The ground state masses (J=0 and J=1) of heavy mesons and magnetic moments of heavy mesons with J=1 using the effective mass of the confined quarks are computed. The obtained results are very close to the ones obtained in experiments or in other works. Key words: Confining potential, hyperfine interaction, Heavy mesons.