arXiv subjects

A. Herzáň

Publications and source records attributed to A. Herzáň.

7 recordsLinked to original sources

arXiv2026

Charge radii of Cl isotopes from x-ray spectroscopy of muonic atoms

Nuclear charge radii are vital for nuclear and atomic physics, the determination of fundamental constants, and searches for new physics. Muonic atoms, where a single negative muon orbits a nucleus, are sensitive tools for determining nuclear radii due to the large wavefunction overlap of the muon and nucleus. Here we report on a new measurement of the $2, 3, 4p\to1s$ x-ray energies in muonic $^{35,37}$Cl with uncertainties reaching 18 ppm. By employing a large-scale germanium detector array, it was possible to extract these energies from a high statistics dataset using highly enriched samples of only a few tens of milligrams. Combining these results with state-of-the-art atomic and nuclear theory input, the charge radii of the stable chlorine isotopes were determined to be $R(^{35}\text{Cl}) = 3.3333(23)~fm$ and $R(^{37}\text{Cl}) = 3.3444(23)~fm$. This is an order of magnitude more precise and significantly different from previously tabulated values. Our new values solve a discrepancy observed for the charge radius difference in mirror nuclei, agreeing with the overall global trend. The charge radius difference $δ\langle r^2 \rangle (^{37}\text{Cl} - {^{35}\text{Cl}}) = -0.0776(64)~fm^2$ we extract is 25 times more precise than the previous values. This precision is crucial for establishing reference values for future laser spectroscopy measurements of radioactive isotopes.

nucl-ex↗

arXiv2025

Modern approach to muonic x-ray spectroscopy demonstrated through the measurement of stable Cl radii

Recent advances in muonic x-ray experiments have reinvigorated efforts in measurements of absolute nuclear charge radii. Here, a modern approach is presented, and demonstrated through determination of the charge radii of the two stable chlorine nuclides $^{35}$Cl and $^{37}$Cl. Knowledge of these radii has implications for fundamental studies in nuclear and atomic physics. For this purpose, a state-of-the-art experiment was performed at the $π$E1 beamline in the Paul Scherrer Institute (Switzerland), using a large-scale HPGe detector array in order to extract precise energies of the muonic $^{35}$Cl and $^{37}$Cl $np1s$ transitions. The nuclear charge radius extraction relies on modern calculations for QED effects and nuclear polarization with rigorous uncertainty quantification, including effects that were not accounted for in older studies. Additionally, we established a new method for applying the nuclear shape correction directly from energy density functionals, which are amenable to isotopes for which no high-quality electron scattering experiments are available. The resulting charge radii are $3.3335(23) fm$ for $^{35}$Cl and $3.3445(23) fm$ for $^{37}$Cl, thus improving the uncertainty of the available electron scattering values by a factor of seven. The correlation of several observables was evaluated between the different isotopes in order to produce a more precise value of the differential mean square charge radius $δ\langle r^2 \rangle^{37, 35}=+0.0771(66) fm^{2}$. In this case, improvement of the uncertainty by more than one order of magnitude was achieved compared to the literature value. This precision is sufficient to use this differential as input for isotope shift factor determination.

nucl-ex↗

arXiv2025

Cross-section of the ${^{\rm nat}\rm{Ni}}(γ,{\rm p} x\rm n)^{58}\rm{Co}$ reaction at the bremsstrahlung end-point energy of 35-94 MeV

The photoproduction of the $^{58}\rm{Co}$ nuclei on ${^{\rm nat}\rm{Ni}}$ was studied using the induced $γ$-activity method and off-line $γ$-ray spectrometric technique. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT, Ukraine. The total flux-averaged cross-section $\langle{σ(E_{\rm{γmax}})}\rangle$ for the ${^{\rm nat}\rm{Ni}}(γ,{\rm p} x\rm n)^{58}\rm{Co}$ reaction has been measured in the range of bremsstrahlung end-point energies $E_{\rm{γmax}}$ = 35-94 MeV. The obtained $\langle{σ(E_{\rm{γmax}})}\rangle$ were compared with theoretical estimates. The theoretical values of $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm th}$ were calculated using the partial cross-sections $σ(E)$ from the TALYS1.96 code for different level density models and gamma strength functions.

nucl-ex↗

arXiv2024

Photoproduction of the ${^{55-57}}$Co nuclei on ${^{\rm nat}}$Ni at the bremsstrahlung end-point energy of 35-94 MeV

Production of the ${^{55-57}}$Co nuclei on ${^{\rm nat}}$Ni in photonuclear reactions using bremsstrahlung gamma photon irradiation with end-point energy $E_{\rm{γmax}}$ between 35 and 94~MeV has been studied. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT using the methods of $γ$ activation and off-line $γ$-ray spectroscopy. The obtained experimental flux-averaged cross-sections $\langle{σ(E_{\rm{γmax}})}\rangle$ agree with the data found in literature. The theoretical flux-averaged cross-sections $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{th}}$ for the production of ${^{55-57}}$Co and ${^{55-57}}$Ni were estimated using the cross-section values $σ(E)$ from the TALYS1.95 code and bremsstrahlung spectra of gamma photons calculated by GEANT4.9.2. The experimental results for ${^{56,57}}$Co agree with the cumulative $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{th}}$. However theoretical prediction fails to reproduce the measured cross-sections for the production of ${^{55}}$Co.

nucl-ex↗

arXiv2023

Production of ${^{180\rm{m}}}$Hf in photoproton reaction ${^{181}}$Ta$(γ,p)$ at energy $E_{\rm{γmax}}$ = 35-95 MeV

The production of the $^{180\rm{m}}\rm{Hf}$ nuclei in the photoproton reaction ${^{181}\rm{Ta}}(γ,p)$ was studied at end-point bremsstrahlung energies $E_{\rm{γmax}}$ = 35-95 MeV. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT with the use of the $γ$ activation and off-line $γ$-ray spectroscopy. The experimental values of the bremsstrahlung flux-averaged cross-sections $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{m}}$ for the ${^{181}\rm{Ta}}(γ,p)^{180\rm{m}}\rm{Hf}$ reaction were determined, and at $E_{\rm{γmax}} > 55$ MeV obtained for the first time. The measured values, also as the literature data, are significantly exceed the theoretical flux-averaged cross-sections $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{th}}$. The $\langle{σ(E_{\rm{γmax}})}\rangle_{\rm{th}}$ values were calculated using the cross-section $σ(E)$ computed with the TALYS1.95 code for six different level density models. A comparative analysis of the calculated total cross-sections for the reactions ${^{181}\rm{Ta}}(γ,p)^{180}\rm{Hf}$ and ${^{181}\rm{Ta}}(γ,n)^{180}\rm{Ta}$ was performed. It was shown that the photoproton $(γ,p)$ to photoneutron $(γ,n)$ strength ratio is consistent with the estimates based on the isospin selection rules and the value from the $(e,e'p)$ experiment.

nucl-ex↗

arXiv2021

First observation of high-$K$ isomeric states in $^{249}$Md and $^{251}$Md

Decay spectroscopy of the odd-proton nuclei $^{249}$Md and $^{251}$Md has been performed. High-$K$ isomeric states were identified for the first time in these two nuclei through the measurement of their electromagnetic decay. An isomeric state with a half-life of $2.8(5)$ ms and an excitation energy $\geq 910$ keV was found in $^{249}$Md. In $^{251}$Md, an isomeric state with a half-life of $1.4(3)$ s and an excitation energy $\geq 844$ keV was found. Similarly to the neighbouring $^{255}$Lr, these two isomeric states are interpreted as 3 quasi-particle high-$K$ states and compared to new theoretical calculations. Excited nuclear configurations were calculated within two scenarios: via blocking nuclear states located in proximity to the Fermi surface or/and using the quasiparticle Bardeen-Cooper-Schrieffer method. Relevant states were selected on the basis of the microscopic-macroscopic model with a deformed Woods-Saxon potential. The most probable candidates for the configurations of $K$-isomeric states in Md nuclei are proposed.

nucl-ex↗

arXiv2013

Spectroscopy of proton-rich 66^Se up to J^π = 6^+: isospin-breaking effect in the A = 66 isobaric triplet

Candidates for three excited states in the 66^Se have been identified using the recoil-β tagging method together with a veto detector for charged-particle evaporation channels. These results allow a comparison of mirror and triplet energy differences between analogue states across the A = 66 triplet as a function of angular momentum. The extracted triplet energy differences follow the negative trend observed in the f_7/2 shell. Shell-model calculations indicate a continued need for an additional isospin non-conserving interaction in addition to the Coulomb isotensor part as a function of mass.

nucl-ex↗