Search results for "Actinium"

Developments towards in-gas-jet laser spectroscopy studies of actinium isotopes at LISOL

2015

To study exotic nuclides at the borders of stability with laser ionization and spectroscopy techniques, highest efficiencies in combination with a high spectral resolution are required. These usually opposing requirements are reconciled by applying the in-gas-laser ionization and spectroscopy (IGLIS) technique in the supersonic gas jet produced by a de Laval nozzle installed at the exit of the stopping gas cell. Carrying out laser ionization in the low-temperature and low density supersonic gas jet eliminates pressure broadening, which will significantly improve the spectral resolution. This article presents the required modifications at the Leuven Isotope Separator On-Line (LISOL) facility…

A radiometric and petrographic approach to risk assessment at Alte Madonie Mounts region (Sicily, Italy)

2013

The main goal of this work was to assess the radiological hazard at Alte Madonie Mounts region (north-central Sicily, Italy) in response to rumours of an increase in the incidence of cancer in this area. A correlation between the natural radionuclide contents and the petrographic features of the soil and rock samples was also evaluated. A total of 41 samples of selected soils and rocks were collected, powdered, dried and sealed in 'Marinelli' beakers for 20 d prior to measurement to ensure that a radioactive equilibrium between (226)Ra and (214)Bi had been reached. A gamma-ray spectrometer was used to quantify the radioactivity concentrations. To determine (238)U and (232)Th activities, the…

Detection of the Lowest-Lying Odd-Parity Atomic Levels in Actinium

2020

Two lowest-energy odd-parity atomic levels of actinium, 7s27pP21/2o, 7s27pP23/2o, were observed via two-step resonant laser-ionization spectroscopy and their respective energies were measured to be 7477.36(4) and 12 276.59(2) cm-1. The lifetimes of these states were determined as 668(11) and 255(7) ns, respectively. In addition, we observed the effect of the hyperfine structure on the line for the transition to P23/2o. These properties were calculated using a hybrid approach that combines configuration interaction and coupled-cluster methods, in good agreement with the experiment. The data are of relevance for understanding the complex atomic spectra of actinides and for developing efficien…

Identification of Thorium-236

1973

Abstract The new nuclide 236Th has been produced via the (γ, 2 p) reaction by irradiation of 238U with 140 MeV bremsstrahlung. After chemical separation of thorium, the half-life was determined to be 36 ± 3 min -from the growth-decay curve of the strongest γ-ray transition of the daughter nuclide, 9 min 236Pa.

First Determination of the Ionization Potential of Actinium and First Observation of Optical Transitions in Ferminm

2002

For the determination of the first ionization potential of actinium, 227Ac was electrodeposited on a Ta backing and covered with ~1 μm Zr. From this filament, Ac atoms were evaporated at ≥ 1250 °C. By resonant excitation with UV light of 388.67 nm and subsequent excitation with light of ca. 568 nm, Ac was ionized in an external electrical field. By determining the ionization thresholds as a function of the electrical field strength and by extrapolation to zero field strength, the first ionization potential of 43398(3) cm−1 = 5.3807(3) eV was measured.About 1 ng of 255Fm, half life 20.1 h, was prepared at ORNL by milking from 255Es produced in the High Flux Isotope Reactor and shipped to Mai…

Production of refractory elements close to the Z=N line using the ion-guide technique

1998

Production of neutron-deficient isotopes of refractory elements in the A = 80-88 region was studied using the IGISOL technique and the 165 MeV Si-32 + Ni-nat reaction. Radioactive isotopes of Y through Mo could be produced up to the M-T = + 1 line. New information on the decay of the A = 82 and 85 nuclei, including a more detailed decay scheme and more accurate half-life for Y-82, was obtained. (C) 1998 Elsevier Science B.V. All rights reserved.

Decay properties of 114Ag

1971

Absence of delayed fission in the? ?-decay of 2.3 min238Pa

1985

We have searched for beta-delayed fission in the decay of 2.3 min238Pa produced in the238U(n,p) reaction with 14.7 MeV neutrons. Through microprocessor-controlled chemical separations of protactinium about 109 atoms of238Pa were isolated and exposed to fission track detectors. From the absence of fission tracks an upper limit for the betadelayed fission probability of238Pa, i.e.Pβf<2.6 10−8, is obtained at 95% confidence level. This rules out positive evidence for this decay mode of238Pa reported elsewhere. Simple theoretical estimates ofPβf range from 10−7 to 10−9.

Heavy isotopes of actinium: 229Ac, 230Ac, 231Ac and 232Ac

1973

Abstract By irradiation of 232Th with 150-MeV bremsstrahlung and with 14-MeV neutrons, three new neutron-rich isotopes of actinium, 230Ac, 231Ac and 232Ac, were produced and identified and the previously reported isotope, 229Ac, was confirmed. The actinium isotopes were chemically isolated by a fast procedure based on elution with α-hydroxyisobutyric acid from cation exchange resins. For 229Ac, a half-life of 62·7 ± 0·5 min and a β-ray energy of 1·14 ± 0·15 MeV were found; 35 γ-rays were observed, the strongest ones with the following energies and relative intensities: 135·3(34), 146·4(35), 164·6(100), 252·2(24), 261·9(39), 317·0(23), 539·9(20), 569·1(91), and 605·2 keV(23). For 230Ac, a ha…

Neutron-rich isotopesTi54−57

1996

The neutron-rich isotopes $^{54\mathrm{\ensuremath{-}}57}\mathrm{Ti}$ and $^{58\mathrm{\ensuremath{-}}60}\mathrm{Cr}$ are produced by fragmentation of a 64.5 MeV/nucleon $^{65}\mathrm{Cu}^{26+}$ beam in a 90 mg/${\mathrm{cm}}^{2}$ $^{9}\mathrm{Be}$ target. Following particle identification by energy loss and time of flight, the radioactive decay was observed by \ensuremath{\beta} singles and \ensuremath{\beta}\ensuremath{\gamma}-coincidence measurements. The results obtained for $^{58\mathrm{\ensuremath{-}}60}\mathrm{Cr}$ are compared to previous results, whereas the decay of the $^{54\mathrm{\ensuremath{-}}57}\mathrm{Ti}$ isotopes is studied here. \ensuremath{\gamma}-ray intensities and en…