A novel procedure for measuring the concentrations of lithium and beryllium in different inorganic and biological samples has been studied using18O heavy-ion activation analysis. The specific reactions,7Li(18O,n)2cF and9Be(180,2)19O, are sensitive and selective if the bombardment energy is 25-MeV18O4+. The detection limits for non-destructive analyses are 10 ng Li and 2 ng Be for a 100-second cyclic irradiation. The technique has been tested by analyzing NBS reference materials. It can be applied to a large range of solid samples.
The use of 7 MeV6Li+ for heavy ion activation analysis was investigated. A survey of reactions, involving targets of lithium through oxygen inclusive,
were studied for production of β+ radioactivation products with half-lives of 101−105 seconds. Specific activities for all reactions under the experimental conditions are reported and their use for analysis
Nondestructive heavy ion activation analysis has been used to determine the carbon content in various NBS SRM steel samples
with a 7.0MeV6Li+ beam. The reaction12C(6Li, αn)13N allows for carbon analysis with the only possible interference being beryllium,9Be(6Li, 2n)13N. Under interference-free conditions, and employing a post-irradiation etch, the detection limit for carbon analysis in steel
was 5 ppm.
Authors:J. Mcginley, L. Žikovský, and E. Schweikert
The use of heavy ion activation as a method for the analysis of hydrogen and deuterium has been evaluated. Thick target yields
from reactions of7Li,10B,11B and19F on1H and2H have been determined; activation curves for many of these reactions are presented and interferences are evaluated. Hydrogen
has been determined in titanium via1H(10B, α)7Be at the 100 and 33 ppm levels with relative precisions of 8 to 10%.
A novel procedure for measuring the concentration of trace beryllium in different samples has been studied using11B heavy ion activation analysis. The specific reaction,9Be/11B, 2n/18F, is sensitive and selective when using a 10 MeV11Be3+ bombardment energy. The detection limit for a nondestructive analysis is 0.1 ng for a 2 h irradiation in a A cm–2 beam current. A precision of 12% was achieved at the 50 g g–1 level. Beryllium has been determined in a standard beryllium-copper alloy NBS-SRM C1123. Glass samples containing up to 61 trace elements were also analyzed nondestructively. When using a clean vacuum irradiation chamber, the technique might allow ultra-trace determinations, dealing with solid samples of a few milligrams.
No-carrier-added (nca) 208,209,210At was produced for the first time from 9Be induced reaction on thallium carbonate target at BARC-TIFR pelletron, Mumbai, India. The target of 4 mg/cm2 thickness was prepared by centrifugation technique. Nca At was separated from the thallium target by liquid–liquid extraction
using liquid cation exchanger HDEHP dissolved in cyclohexane and liquor ammonia.
11B induced radioactivation was used to study the trace determination of light elements with 1
17. 49 nuclear reactions were investigated with ion beam energies ranging from Elab=10 MeV to Elab=27 MeV. Five elements were found to be determinable nondestructively, selectively and sensitively: Li, Be, B, Mg and Si. Nuclear interferences have also been defined and quantified. The technique has been applied to simultaneous Li-B trace determinations in glass samples and to Mg determination in Al2O3 ceramic material.
A procedure for measuring trace amounts of Li and Be in different types of samples has been studied using a 12.5 MeV14N beam. At this energy the principal nuclear reactions are6Li(14N, d)18F,7Li(14N, t)18F, and9Be(14N, αn)18F. Detection limit for destructive analysis for either beryllium or lithium has been calculated at 300 ppb with a determination
limit of 5 ppm for an irradiation with a beam of 1 μA·h/cm2. Destructive analysis was performed on CANMET SY-2 and USGS BCR-1 (rock samples 1–10 ppm Be). Non-destructive analysis for
beryllium and lithium was performed on NBS SRM 610 (500 ppm trace element glass), NBS 612 (50 ppm trace element glass), and
NBS SRM 181 (Spodumene ore, 6.4% Li2O). Detection limit of 2 ppm has been calculated for nondestructive analysis of either lithium or beryllium.
18O induced radioactivation may be used for the trace detection of1H via1H (18O, n)18F. Matrices in which this reaction is interference-free include: Al, Si, S, K, Ti, V, Ni, Cu and Zn. However, due to numerous
radioisotopes created at the bombarding energies used (E≥51 MeV), a post-irradiation chemical separation of18F is required.18O activation also appears as a promising means for the trace determination of S[S(18O, x)47V], Si[Si(18O, x)43–44Sc] and B[B(18O, x)37Mg].
10B induced radioactivation was used for the trace determination of hydrogen via the1H(10B )7Be reaction. At 27 MeV10B++, only boron and magnesium present small nuclear interferences. An activation curve has been established by bombarding stacks of thin mylar foils. The comparison of this curve with the excitation function for the forward reaction, namely10B(p, )7Be, shows that the recoil range from superficial hydrogen atoms is small. Hydrogen has been determined in titanium and lead bronze at the 100 ppm level. Studies of 21 potential interfering elements suggest that10B activation might be suitable for the trace determination of lithium [6Li(10b,n)15O and7Li(10B, 2n)15O] and oxygen [18O(10B,)24Na].