The preparation of stable and actinide nuclide targets for nuclear measurements

Abstract

Specifications for isotopic targets of both stable and actinide nuclides for nuclear measurements are very varied and individually very stringent. The majority of the targets are required to be of specified isotopic and chemical purity, well characterised and uniformly deposited over a precisely defined area. Mass assay of actinide targets may be requested to an accuracy of + 0.1%, resolutions of <10 KeV FWHM may be requested for infinitely thin alpha sources and the Schmidt and Pleasonton criteria must be met for 252Cf fission fragment energy calibration sources. In order to cater for this wide range of requirements it is necessary to have available many preparation and calibration techniques. Actinide sources with activities in the range 0.01 pCi to several hundred mCi and targets up to a few mg/cm2 are prepared by one of the following techniques, vacuum evaporation, painting, electrodeposition or the use of TEG as a spreading agent. These targets may be assayed quantitatively by absolute alpha counting and weighing and qualitatively by alpha spectrometry. Stable isotope targets with thickness varying from a few pg/cm2 to several hundred mg/cm2 are prepared primarily by vacuum evaporation and rolling. Mass assay is to + 10% or better, the achievable accuracy being a function of substrate and target thickness. Activities of particular interest include the preparation of fission foils to be used in a series of flux inter-comparison measurements being organised by the Bureau International des Poids et Mesures, the preparation of stable isotope alloy foils for Mossbauer studies and the preparation of actinide targets on thin substrates.

Smooth crack-free targets for nuclear applications produced by molecular plating

“…Targets are an essential component in experimental nuclear science as a source of stationary nuclei, e.g., for atomic and nuclear spectroscopy or nuclear reaction studies [1][2][3]. Generally, targets should be chemically pure, uniform, homogeneous, crack-free over the area of interest, and well adherent to the deposition substrate.…”

Immobilization of Actinides by Electropolymerization of Acrylonitrile : Application to the Preparation of Alpha Spectroscopy Sources

“…According to Glover et al [10] an other requested specification for a sources is an observable resolution of <10 keV FWHM for a single peak. This low value is reached only by the vacuum evaporation technique with 239 Pu peaks [10].…”

“…This low value is reached only by the vacuum evaporation technique with 239 Pu peaks [10]. Alpha fine structure from a vacuum sublimed 241 Am source evidences quite a broad peak at 5.48 MeV with 13.8 keV FWHM [11].…”

Modeling and production of 240Am by deuteron-induced activation of a 240Pu target

“…A review of literature showed that higher quantities of plutonium were deposited from non-aqueous solvents than from aqueous solvents. Further, a non-aqueous solvent reduces the formation of hydrogen bubbles from electrolysis of water that cause an uneven surface in the deposit [20][21][22][23]. The literature reports production of Pu targets containing 200-400 lg/ cm 2 [24][25][26], with some obtaining loadings as high as 987 lg/ cm 2 [20] using a setup comparable to the one used in this work.…”