Search results for " nuclear physics"
showing 10 items of 83 documents
High-spin spectroscopy of 140Nd
2013
The population of the high-spin states in 140Nd was investigated using the reaction 96Zr(48Ca,4n). The results from two experiments, one with the EUROBALL array and one with the JUROGAM II + RITU + GREAT setup employing the recoil decay tagging technique, have been combined to develop a very detailed level scheme for 140Nd. Twelve bands of quadrupole transitions and eleven bands of dipole transitions were identified and their connections to low-lying states were established. Calculations using the cranked Nilsson-Strutinsky and the tilted axis cranking models were used to interpret the observed structures. The overall good agreement between the experimental results and the calculations assu…
Electromagnetic transition strengths in 109Te
2012
Lifetime measurements have been made in the neutron-deficient nucleus 109Te using the coincident recoil distance Doppler-shift method. The experimental B(E2) values have been compared with state-of-the-art shellmodel calculations using the monopole-corrected realistic charge-dependent Bonn nucleon-nucleon potential. Lifetimes in the νh11/2 band are consistent with an interpretation based on the deformation driving properties of a single valence neutron outside of the even-even tellurium core and highlight the unexpected presence of collective behavior as the N = 50 shell closure is approached. Lifetime measurements for the low-lying positive-parity states also appear to correlate well with …
First observation of excited states of 173Hg
2012
The neutron-deficient nucleus 173Hg has been studied following fusion-evaporation reactions. The observation of the decay of excited states via γ radiation are reported for the first time and a tentative level scheme is proposed. The proposed level scheme is discussed within the context of the systematics of neighboring neutron-deficient Hg nuclei. In addition to the γ -ray spectroscopy, the α decay of this nucleus has been measured yielding superior precision to earlier measurements. peerReviewed
First-forbidden transitions in the reactor anomaly
2018
We study the dominant forbidden transitions in the antineutrino spectra of the fission actinides from 4 MeV onward using the nuclear shell model. Through explicit calculation of the shape factor, taking into account Coulomb corrections, we show the expected changes on cumulative electron and antineutrino spectra. Compared to the usual allowed approximation this results in a minor decrease of electron spectra from 4 MeV and onward, whereas an increase of several percent is observed in antineutrino spectra. We show that, despite their limited number, forbidden transitions dominate the spectral flux for most of the experimentally accessible range. Based on the shell model calculations we attem…
Low-lying excited states in the neutron-deficient isotopes 163Os and 165Os
2013
Excited states in the neutron-deficient isotopes 163Os and 165Os were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The 163Os and 165Os nuclei were populated via the 106Cd(60Ni,3n) and 92Mo(78Kr,2p3n) reactions at bombarding energies of 270 MeV and 357 MeV, respectively. Gamma-ray emissions from these nuclei have been established unambiguously using the recoil-decay tagging technique and a coincidence analysis has allowed level schemes to be established. These results suggest that the yrast states are based upon negative-parity configurations originating from the νf7/2 and νh9/2 orbitals. peerReviewed
Measurement and microscopic description of odd-even staggering of charge radii of exotic copper isotopes
2020
Isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. In charge radii of short-lived copper isotopes, a reduction of this effect is observed when the neutron number approaches fifty. The mesoscopic nature of the atomic nucleus gives rise to a wide array of macroscopic and microscopic phenomena. The size of the nucleus is a window into this duality: while the charge radii globally scale as $A^{1/3}$, their evolution across isotopic chains reveals unanticipated structural phenomena [1-3]. The most ubiquitous of these is perhaps the Odd-Even Staggering (OES) [4]: isotopes with an odd number of neutrons are usually smaller in size than …
The FIRST experiment at GSI
2012
The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at the SIS accelerator of GSI laboratory in Darmstadt has been designed for the measurement of ion fragmentation cross-sections at different angles and energies between 100 and 1000 MeV/nucleon. Nuclear fragmentation processes are relevant in several fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The start of the scientific program of the FIRST experiment was on summer 2011 and was focused on the measurement of 400 MeV/nucleon 12C beam fragmentation on thin (8 mm) graphite target. The detector is partly based on an alread…
Structure of transactinide nuclei with relativistic energy density functionals
2013
A microscopic theoretical framework based on relativistic energy density functionals (REDFs) is applied to studies of shape evolution, excitation spectra, and decay properties of transactinide nuclei. Axially symmetric and triaxial relativistic Hartree-Bogoliubov (RHB) calculations, based on the functional DD-PC1 and with a separable pairing interaction, are performed for the even-even isotopic chains between Fm and Fl. The occurrence of a deformed shell gap at neutron number $N=162$ and its role on the stability of nuclei in the region around $Z=108$ is investigated. A quadrupole collective Hamiltonian, with parameters determined by self-consistent constrained triaxial RHB calculations, is…
Charged-current neutrino-nucleus scattering off the even molybdenum isotopes
2012
Neutrinos from supernovae constitute important probes of both the currently unknown supernova mechanisms and of neutrino properties. Reliable information about the nuclear responses to supernova neutrinos is therefore crucial. In this work, we compute the cross sections for the charged-current neutrino-nucleus scattering off the even-even molybdenum isotopes. The nuclear responses to supernova neutrinos are subsequently calculated by folding the cross sections with a Fermi-Dirac distribution.
Fermi-Dirac correlations in Lambda pairs in hadronic Z decays
2000
Two-particle correlations of Lambda Lambda and pairs have been studied in multihadronic Z decays recorded with the ALEPH detector at LEP in the years from 1992 to 1995. The correlations were measured as a function of the four-momentum difference Q of the pair. A depletion of events is observed in the region Q 2 GeV the fraction of pairs with spin one is consistent with the value of 0.75 expected for a statistical spin mixture, whilst for Q pairs, where no Fermi-Dirac correlations are expected, the spin one fraction is measured to be consistent with 0.75 over the entire analysed Q range. (C) 2000 Elsevier Science B.V. All rights reserved.