Search results for "Neon"
showing 10 items of 760 documents
Line Identification of Atomic and Ionic Spectra of Holmium in the Near-UV. Part I. Spectrum of Ho i
2017
The Fourier Transform spectra of a Holmium hollow cathode discharge lamp have been investigated in the UV spectral range from 25,000 up to 31,530 cm−1 (317 to 400 nm). Two Ho spectra have been measured with neon and argon as buffer gases. Based on the intensity ratios from these two spectra, a distinction was made between atomic and ionic lines (ionic lines are discussed in an accompanying paper). Using the known Ho i energy levels, 71 lines could be classified as transitions of atomic Ho, 34 of which have not been published previously. Another 32 lines, which could not be classified, are listed in the literature and assigned as atomic Ho. An additional 370 spectral lines have been assigned…
Lifetime measurements in mirror nuclei31S and31P: A test for isospin mixing
2011
Using the 20Ne + 12C fusion-evaporation reaction at E20Ne = 33 MeV and the multidetector array GASP in conjuction with the EUCLIDES charged particle detector, angular correlations of coincident pairs of γ transitions and lifetimes in mirror nuclei 31S and 31P have been measured at the Piave-Alpi accelerator of the Laboratori Nazionali di Legnaro. A comparison of the determined B(E1) strengths of the analog mirror 7/2− → 5/2+ transitions indicates the presence of a violation of isospin symmetry.
Laser spectroscopy measurement of isotope shifts and nuclear moments of short-lived neon isotopes
2003
Within the scope of a laser spectroscopy study of nuclear structure in the sd shell we are measuring nuclear moments and isotope shifts of neon isotopes. An ultra-sensitive variant of collinear laser spectroscopy [1, 2] is applied to a neutralized fast beam from ISOLDE (CERN). The non-optical detection is based on optical pumping, state selective collisional ionization and β-activity counting. This method gives access in particular to the short-lived isotopes in the extended chain of 17–26,28Ne.
On X-ray Optical Depth in the Coronae of Active Stars
2007
We have investigated the optical thickness of the coronal plasma through the analysis of high-resolution X-ray spectra of a large sample of active stars observed with the High Energy Transmission Grating Spectrometer on Chandra. In particular, we probed for the presence of significant resonant scattering in the strong Lyman series lines arising from hydrogen-like oxygen and neon ions. The active RS CVn-type binaries II Peg and IM Peg and the single M dwarf EV Lac show significant optical depth. For these active coronae, the Lya/Lyb ratios are significantly depleted as compared with theoretical predictions and with the same ratios observed in similar active stars. Interpreting these decremen…
Measurements of charge state distributions of 0.74 and 1.4 MeV/u heavy ions passing through dilute gases
2017
In many modern heavy-ion accelerator facilities, gas strippers are used to increase the projectile charge state for improving the acceleration efficiency of ion beams to higher energies. For this application, the knowledge on the behavior of charge state distributions of heavy-ions after passing through dilute gases is of special interest. Charge state distributions of uranium ($^{238}\mathrm{U}$), bismuth ($^{209}\mathrm{Bi}$), titanium ($^{50}\mathrm{Ti}$), and argon ($^{40}\mathrm{Ar}$) ion beams with energies of $0.74\text{ }\mathrm{MeV}/\mathrm{u}$ and $1.4\text{ }\mathrm{MeV}/\mathrm{u}$ after passing through hydrogen (${\mathrm{H}}_{2}$), helium (He), carbon dioxide (${\mathrm{CO}}_{…
Radioactivity of neutron-rich oxygen fluorine and neon isotopes
1999
The $\ensuremath{\gamma}$ radiation and neutrons emitted following the $\ensuremath{\beta}$ decays of ${}^{24}\mathrm{O},$ ${}^{25--27}\mathrm{F},$ and ${}^{28\ensuremath{-}30}\mathrm{Ne}$ have been measured. The nuclides were produced in the quasifragmentation of a 2.8 GeV ${}^{36}\mathrm{S}$ beam, separated in-flight and identified through time-of-flight and energy-loss measurements. The ions were stopped in a silicon detector telescope, which was used to detect the $\ensuremath{\beta}$ particles emitted in their subsequent radioactive decay. The coincident $\ensuremath{\gamma}$ rays were measured using four large volume germanium detectors mounted close to the implantation point and the …
Shell-model and Hartree-Fock calculations for even-mass O, Ne, and Mg nuclei
1999
Shell-model and deformed Hartree-Fock plus BCS calculations are reported for even-even nuclei [sup 18[minus]30]O, [sup 18[minus]36]Ne, and [sup 20[minus]42]Mg; shell-model calculations additionally included [sup 38,40]Ne and [sup 44,46,48]Mg. Ground-state binding energies and 2[sub 1][sup +] quadrupole moments are calculated by both models. Shell-model calculations, aided by a new truncation method, include 2[sub 1][sup +] excitation energies and magnetic moments. Hartree-Fock calculations with SkI6, RATP, Z[sub [sigma]][sup [asterisk]], and SkX Skyrme forces include ground-state deformations and rms radii; SkI6 gives the best overall agreement with experiment. The two models are compared w…
Helium burning of22Ne
1989
The22Ne(α, γ)26Mg and22Ne(α, n)25Mg reactions were investigated forE α(lab) from 0.71 to 2.25 MeV. Neon gas enriched to 99% in22Ne was recirculated in a differentially pumped gas target system of the extended type. Theγ-ray transitions were observed with Ge(Li) detectors and the neutrons with3He ionization chambers. A previously known resonance at ER(lab)=2.05 MeV was verified and 15 new resonances were found in the energy range covered, with the lowest at ER(lab)=0.83 MeV. Information on resonance energies, widths, strengths,γ-ray branching ratios, as well asJ π assignments, is reported. The energy range investigated corresponds to the important temperature range ofT 9 from 0.3 to 1.4 (109…
Nuclear moments of neon isotopes in the range fromNe17at the proton drip line to neutron-richNe25
2005
Nuclear moments of odd-A neon isotopes in the range 17 ≤ A ≤ 25 have been determined from optical hyperfine structures measured by collinear fast-beam laser spectroscopy. The magnetic dipole moments of 17 Ne, 23 Ne and 25 Ne, as well as the electric quadrupole moment of 23 Ne are either reported for the first time or improved considerably. The measurements also decide for a 1/2 + ground state of 25 Ne. The behavior of the magnetic moments of the proton drip-line nucleus 17 Ne and its mirror partner 17 N suggests isospin symmetry. Thus, no clear indication of an anomalous nuclear structure is found for 17 Ne. The magnetic moments of the investigated nuclei are discussed in a shell-model appr…
Effects of weakly coupled channels on quasielastic barrier distributions
2009
Heavy-ion collisions often produce fusion barrier distributions with structures displaying a fingerprint of couplings to highly collective excitations. Similar distributions can be obtained from large-angle quasielastic scattering, although in this case, the role of the many weak direct-reaction channels is unclear. For $^{20}\mathrm{Ne}+^{90}\mathrm{Zr}$, we have observed the barrier structures expected for the highly deformed neon projectile; however, for $^{20}\mathrm{Ne}+^{92}\mathrm{Zr}$, we find significant extra absorption into a large number of noncollective inelastic channels. This leads to smearing of the barrier distribution and a consequent reduction in the ``resolving power'' o…