Positron Emission Intensity in the Decay of 86gY for Use in Dosimetry Studies.

The ß+-emitting radionuclide 86gY (t1/2 = 14.7 h) forms a matched-pair with the ß--emitting therapeutic radionuclide 90Y (t1/2 = 2.7 d) for theranostic application in medicine. This approach demands a precise knowledge of the positron emission probability of the PET nuclide which was until recently rather uncertain for 86gY. In this work, an 86gY source of high radionuclidic purity was prepared and a direct measurement of the positron emission intensity per 100 decay of the parent (hereafter "positron emission intensity") was performed using high-resolution HPGe detector γ-ray spectroscopy. The electron capture intensity was also determined as an additional check by measuring the Kα and Kß X-rays of energies 14.1 and 15.8 keV, respectively, using a low energy HPGe detector. From those measurements, normalized values of 27.2 ± 2.0% for ß+-emission and 72.8 ± 2.0% for EC were obtained. These results are in excellent agreement with values recently reported in the literature based on a detailed decay scheme study.

Measurement of the 160Gd(p,n)160Tb excitation function from 4-18 MeV using stacked-target activation.

The  160Gd(p,n)160Tb excitation function was measured between 4-18 MeV using stacked-target activation at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. Nine copper and eight titanium foils served as proton fluence monitor foils, using the  natCu(p,x)65Zn,  natTi(p,x)48V, and  natTi(p,x)46Sc monitor standards, respectively. Variance minimization using an MCNP v.6.2 model reduced the systematic uncertainties in proton energy and fluence. A priori predictions of the  160Gd(p,n) reaction using ALICE, CoH, EMPIRE, and TALYS, as well as the TENDL database, are compared to the experimentally measured values.

Boutique neutrons advance 40Ar/39Ar geochronology.

We designed and tested a compact deuteron-deuteron fusion neutron generator for application to 40Ar/39Ar geochronology. The nearly monoenergetic neutrons produced for sample irradiation are anticipated to provide several advantages compared with conventional fission spectrum neutrons: Reduction of collateral nuclear reactions increases age accuracy and precision. Irradiation parameters within the neutron generator are more controllable compared with fission reactors. Confidence in the prediction of recoil energies is improved, and their likely reduction potentially broadens applicability of the dating method to fine-grained materials without vacuum encapsulation. Resolution of variation in the 39K(n,p)39Ar neutron capture cross section at 1.3 to 3.2 MeV and discovery of a strong resonance at ~2.4 MeV illuminate future pathways to improve the technique for 40Ar/39Ar dating.