Search results for "nuclear structure"
showing 10 items of 401 documents
Theory of the n = 2 levels in muonic helium-3 ions
2017
The present knowledge of Lamb shift, fine-, and hyperfine structure of the 2S and 2P states in muonic helium-3 ions is reviewed in anticipation of the results of a first measurement of several 2S → 2P transition frequencies in the muonic helium-3 ion, μ3He+. This ion is the bound state of a single negative muon μ- and a bare helium-3 nucleus (helion), 3He++. A term-by-term comparison of all available sources, including new, updated, and so far unpublished calculations, reveals reliable values and uncertainties of the QED and nuclear structure-dependent contributions to the Lamb shift and the hyperfine splitting. These values are essential for the determination of the helion rms charge radiu…
Ordinary muon capture studies for the matrix elements in ββ decay
2018
Precise measurement of $\gamma$-rays following ordinary (non-radiative) capture of negative muons by natural Se, Kr, Cd and Sm, as well as isotopically enriched $^{48}$Ti, $^{76}$Se, $^{82}$Kr, $^{106}$Cd and $^{150}$Sm targets was performed by means of HPGe detectors. Energy and time distributions were investigated and total life time of negative muon in different isotopes was deduced. Detailed analysis of $\gamma$-lines intensity allows to extract relative yield of several daughter nuclei and partial rates of ($\mu$,$\nu$) capture to numerous excited levels of the $^{48}$Sc, $^{76}$As, $^{82}$Br, $^{106}$Ag and $^{150}$Tc isotopes which are considered to be virtual states of an intermedia…
The next generation nuclear instruments: AGATA and NEDA, and nuclear structure studies near N=Z line
2017
The first part of this thesis is devoted to the development of a large array of neutron detectors NEDA (NEutron Detector Array) and their conceptual design using Monte-Carlo simulations. Prior to the development of NEDA, the neutron detection with liquid scintillators is discussed in Chapter 2. In Chapter 3, the design criteria and simulations of NEDA are discussed. NEDA aims to build a neutron detector array with high efficiency, based on liquid scintillators. NEDA will be coupled to the high-purity γ-ray detector arrays, like AGATA, EXOGAM, to be used as a trigger or complementary detector in the contemporary nuclear physics experiments, which aim to investigate the structure of the exoti…
Sensitivity of one-neutron knockout to the nuclear structure of halo nuclei
2019
Background: Information about the structure of halo nuclei are often inferred from one-neutron knockout reactions. Typically the parallel-momentum distribution of the remaining core is measured after a high-energy collision of the exotic projectile with a light target. Purpose:We study how the structure of halo nuclei affects knockout observables considering an eikonal model of reaction. Method: To evaluate the sensitivity of both the diffractive and stripping parallel-momentum distributions to the structure of halo nuclei, we consider several descriptions of the projectile within a halo effective-field theory. We consider the case of Be11, the archetypical one-neutron halo nucleus, impingi…
Dispersive evaluation of the Lamb shift in muonic deuterium from chiral effective field theory
2020
We merge the dispersive relation approach and the ab initio method to compute nuclear structure corrections to the Lamb shift in muonic deuterium. We calculate the deuteron response functions and corresponding uncertainties up to next-to-next-to-next-to-leading order in chiral effective field theory and compare our results to selected electromagnetic data to test the validity of the theory. We then feed response functions calculated over a wide range of kinematics to the dispersion-theory formalism and show that an improved accuracy is obtained compared to that with the use of available experimental data in the dispersive analysis. This opens up the possibility of applying this hybrid metho…
Muonic Lithium atoms: nuclear structure corrections to the Lamb shift
2019
In view of the future plans to measure the Lamb shift in muonic Lithium atoms we address the microscopic theory of the $\mu$-$^6$Li$^{2+}$ and $\mu$-$^7$Li$^{2+}$ systems. The goal of the CREMA collaboration is to measure the Lamb shift to extract the charge radius with high precision and compare it to electron scattering data or atomic spectroscopy to see if interesting puzzles, such as the proton and deuteron radius puzzles, arise. For this experiment to be successful, theoretical information on the nuclear structure corrections to the Lamb shift is needed. For $\mu$-$^6$Li$^{2+}$ and $\mu$-$^7$Li$^{2+}$ there exist only estimates of nuclear structure corrections based on experimental dat…
THE STRUCTURE OF THE NUCLEONS
1980
Electron-proton and electron-deuteron scattering experiments in a wide four momentum range provide information about the structure of the proton and the neutron. The structure is a direct consequence of the hadronic interaction of the nucleon and reveals properties of the strong interaction. Absolute differential cross sections can be expressed in terms of electromagnetic form factors which lead to an understanding of the coupling mechanism between the electromagnetic field and the strongly interacting hadron. The structure can also be discussed in terms of charge densities, but this analysis is strongly restricted by recoil effects. The charge rms radius extracted from recent measurements …
Nuclear structure contribution to the Lamb shift in muonic deuterium
2013
We consider the two-photon exchange contribution to the $2P-2S$ Lamb shift in muonic deuterium in the framework of forward dispersion relations. The dispersion integrals are evaluated using experimental data on elastic deuteron form factors and inelastic electron-deuteron scattering, both in the quasielastic and hadronic range. The subtraction constant that is required to ensure convergence of the dispersion relation for the forward Compton amplitude $T_1(\nu,Q^2)$ is related to the deuteron magnetic polarizability $\beta(Q^2)$. Based on phenomenological information, we obtain for the Lamb shift $\Delta E_{2P-2S}=2.01\pm0.74$ meV. The main source of the uncertainty of the dispersion analysi…
Bridging the nuclear structure gap between stable and super heavy nuclei
2009
International audience; Due to recent advances in detection techniques, excited states in several trans-fermium nuclei were studied in many laboratories worldwide, shedding light on the evolution of nuclear structure between stable nuclei and the predicted island of stability centered around spherical magic numbers. In particular, studies of K-isomers around the Z=100 and N=152 deformed shell closures extended information on the energies of Nilsson orbitals at the Fermi surface. Some of these orbitals originate from spherical states, which are relevant to the magic gaps in super-heavy nuclei. The single-particle energies can be used to test various theoretical predictions and aid in extrapo…
High-spin structure of Xe134
2016
A. Vogt et al. ; 12 págs.; 9 figs.; 1 tab.