Search results for "nuclear structure"
showing 10 items of 401 documents
Новое зкспериментальное подтверждение для ядра8Не
1972
In this work we present the analysis and interpretation of an event, consistent with the production and subsequent decay of the exotic nucleus8He, found in the study of K− interactions with nuclear-emulsion nuclei at different energies.
Microscopic calculations of isospin-breaking corrections to superallowed beta-decay
2011
The superallowed beta-decay rates that provide stringent constraints on physics beyond the Standard Model of particle physics are affected by nuclear structure effects through isospin-breaking corrections. The self-consistent isospin- and angular-momentum-projected nuclear density functional theory is used for the first time to compute those corrections for a number of Fermi transitions in nuclei from A=10 to A=74. The resulting leading element of the CKM matrix, |V_{ud}|= 0.97447(23), agrees well with the recent result by Towner and Hardy [Phys. Rev. C {\bf 77}, 025501 (2008)].
Measurement ofN14(γ, π+)C14(g.s.)at 200 MeV: A Test of the Distorted-Wave Impulse Approximation for Charged-Pion Photoproduction below theΔ(1232)Reso…
1985
Differential cross sections for $^{14}\mathrm{N}(\ensuremath{\gamma}, {\ensuremath{\pi}}^{+})^{14}\mathrm{C}(\mathrm{g}.\mathrm{s}.)$ (${0}^{+}$1) have been measured for an incident photon energy ${E}_{\ensuremath{\gamma}}=200$ MeV at laboratory angles of 45\ifmmode^\circ\else\textdegree\fi{}, 60\ifmmode^\circ\else\textdegree\fi{}, 75\ifmmode^\circ\else\textdegree\fi{}, 90\ifmmode^\circ\else\textdegree\fi{}, 120\ifmmode^\circ\else\textdegree\fi{}, and 140\ifmmode^\circ\else\textdegree\fi{}. Momentum-space distorted-wave-impulse-approximation calculations, using a complete treatment of a one-body pion-photoproduction operator, are found to be in excellent agreement with the experimental data…
Rare weak decays and nuclear structure
2014
Abstract. Weak interactions cause the atomic nuclei to decay via beta and double beta decays. Double beta decays are extremely rare since they are weak-interaction processes of the second order. Also (single) beta decays can be extremely rare. This can be caused by either a large di ff erence between the spins of the initial and final state (the so-called “forbidden” beta decays) or an extremely small Q value (decay energy) of the decay. All these cases are discussed in this article, and particular emphasis is given to the neutrino- less double electron capture on the double beta side of decays. peerReviewed
Unified description of hadronic and electromagnetic reactions of the two-nucleon system
2010
Abstract Studies of the two-nucleon system are essential for a profound understanding of nuclear structure and for the exploration of the limits of the effective description of atomic nuclei in terms of nucleons, mesons and isobars. In the present work, a unified description of hadronic and electromagnetic reactions on the two-nucleon system is developed in the framework of a coupled-channel N N / N Δ -approach which is based on one general Hamiltonian and which treats the pion exchange in the hadronic baryon–baryon interaction as well as in the meson exchange currents in the exact retarded manner. Unitarity and gauge invariance are at least approximately fulfilled. Several hadronic and ele…
Dispersive Evaluation of the Inner Radiative Correction in Neutron and Nuclear $\beta$-decay
2019
We propose a novel dispersive treatment of the so-called inner radiative correction to the neutron and nuclear $\beta$-decay. We show that it requires knowledge of the parity-violating structure function $F_3^{(0)}$ that arises from the interference of the axial vector charged current and the isoscalar part of the electromagnetic current. By isospin symmetry, we relate this structure function to the charged current inelastic scattering of neutrinos and antineutrinos. Applying this new data-driven analysis we obtain a new, more precise evaluation for the universal radiative correction $\Delta_{R}^{V,\,new}=0.02467(22)$ that supersedes the previous estimate by Marciano and Sirlin, $\Delta_R^V…
Nuclear physics of non-standard 0νβ β-decay
2019
The observation neutrinoless double beta (0νβ β) decay remains crucial for understanding lepton number violation. In view of the difficulties to observe the mass mechanism of 0νβ β-decay, investigations of other mechanisms are in order. These non-standard mechanisms can be divided into short-range and long-range mechanisms. Recently, we have started systematic study for all possible short-range and long-range non-standard mechanisms. The aim of this study is twofold: I) to provide explicit formulas for the nuclear matrix elements (NMEs) and phase-space factors (PSFs) from which the decay rate for one or a combination of mechanisms operating at the same time can be calculated; II) to provide…
Nuclear Spins and Magnetic Moments ofCu71,73,75: Inversion ofπ2p3/2andπ1f5/2Levels inCu75
2009
We report the first confirmation of the predicted inversion between the pi2p3/2 and pi1f5/2 nuclear states in the nu(g)9/2 midshell. This was achieved at the ISOLDE facility, by using a combination of in-source laser spectroscopy and collinear laser spectroscopy on the ground states of 71,73,75Cu, which measured the nuclear spin and magnetic moments. The obtained values are mu(71Cu)=+2.2747(8)mu(N), mu(73Cu)=+1.7426(8)mu(N), and mu(75Cu)=+1.0062(13)mu(N) corresponding to spins I=3/2 for 71,73Cu and I=5/2 for 75Cu. The results are in fair agreement with large-scale shell-model calculations.
Mr. Maxwell's journey into hadron country (electromagnetic currents in nuclei)
1993
In these lectures an introduction is given into the main features of nuclear structure investigations by photoabsorption and electron scattering. After a brief review of the general structure of the electromagnetic interaction, the gauge conditions and low-energy theorems for the electromagnetic interaction operators are discussed. The various theoretical schemes for incorporating subnuclear degrees of freedom either as effective operators like the pion exchange current or explicitely like in the model of nuclear isobar configurations are reviewed. At the end, a few specific experiments are discussed as an illustration of what can be learned from such experiments.
Persistence of the Z=28 shell gap in A=75 isobars: Identification of a possible (1/2−) μs isomer in Co75 and β decay to Ni75
2021
Background: The evolution of shell structure around doubly-magic exotic nuclei is of great interest in nuclear physics and astrophysics. In the `south-west' region of $^{78}$Ni, the development of deformation might trigger a major shift in our understanding of explosive nucleosynthesis. To this end, new spectroscopic information on key close-lying nuclei is very valuable. Purpose: We intend to measure the isomeric and $\beta$ decay of $^{75}$Co, with one proton- and two neutron-holes relative to $^{78}$Ni, to access new nuclear structure information in $^{75}$Co and its $\beta$-decay daughters $^{75}$Ni and $^{74}$Ni. Methods: The nucleus $^{75}$Co is produced in relativistic in-flight fiss…