7Li induced radioactivation was used for the trace determination of hydrogen via the1H(7Li, n)7 Be reaction. At 21 MeV7Li, only boron and magnesium present small nuclear interferences. An activation curve has been established by bombarding a stack of thin mylar foils. The comparison of this curve with the excitation function for the forward reaction, namely7Li(p, n)7 Be, shows that the recoil range from the superficial hydrogen atoms is only 1.7 mg·cm–2, allowing post-irradiation etching. Hydrogen has been determined in titanium and lead bronze at the 100 ppm level with a relative precision of 6 to 10%. Studies of 32 potential interfering elements suggest the extension of Li activation to the trace determination of Na[23Na(7Li,6Li)24Na] and K[39K(7Li, d)44m,44Sc].
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.
Fast neutron activation analysis (FNAA) was investigated as a possible on-site preliminary screening technique for metal contamination of soil. Two metals, Cu and Zn, were used in a laboratory setting to evaluate the possibility of detecting metal contamination of soil at or below the maximum permissible metal concentration in soil. Varying quantities of compounds of the selected metals were mixed into a prepared soil column for analysis of signal intensity as a function of concentration in the soil. Experiments were conducted with a sealed tube neutron generator and a germanium gamma-ray detector. Both metals produced signal levels distinguishable from background soil concentrations at the maximum permissible level.
Characteristic K, L and M X-ray and background production trends from high energy heavy ion bombardment were investigated
on a series of target elements (14≤Z≤92) using 0.5 MeV/amu and 1 MeV/amu Nn+, On+, Cun+, Krn+ and Xen+ beams. X-ray production for K and L shell X-rays roughly followed the same trends, i.e. increased yield with projectile size
and energy and decreased yield with increasing X-ray energy. Broad simultaneous multielement coverage can be achieved using
K, L and M Lines. Experimental detection limits of 0.8 to 10 ppm were obtained for elements between Mn and Se with K X-ray
detection, between Sm and Pb using L X-ray detection, and for Th and U via M X-ray detection in biological samples with a
1MeV/amu Kr7+ beam of 70 nA for 1000 s. These detection limits are better for many elements than those obtained with a 1.65 MeV proton
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].
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.
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%.