Engineering topics
Nica, N.
Publications and source records attributed to Nica, N..
United States Nuclear Data Program Annual Report (FY 2022)
This document describes the activities including related metrics performed by the US Nuclear Data Program members during Fiscal Year 2022.
Nuclear Data Sheets for A=153
The experimental results published before August 2020 from the various reaction and decay studies leading to nuclides of Z=55 to Z=72, 153 Ba, 153 La, 153 Ce, 153 Pr, 153 Nd, 153 Pm, 153 Sm, 153 Eu, 153 Gd, 153 Tb, 153 Dy, 153 Ho, 153 Er, 153 Tm, 153 Yb, 153 Lu, 153 Hf in the A=153 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. This work is intended to supersede the previous evaluation of the A=153 nuclides by R.G. Helmer (2006He06), which was published in Nuclear Data Sheets 107, 507 (2006).
K-shell internal conversion coefficient for M4 decay of the 30.8 keV isomer in 93 Nb
The 30.8 keV (1/2) – isomeric state in $^{93}_{41}$Nb decays by an M4 transition to the (9/2) + ground state. Here, we have measured the K-shell internal conversion coefficient α K for this transition in order to test the validity of current methods of calculation for a case with relatively low atomic number, low transition energy, and a high value of α K . Taking the fluorescence yield of niobium to be 0.751(4), we obtain α K = 2.56(9) × 10 4 , a result that agrees with the Dirac-Fock calculations that take into account the presence of a K vacancy in the final state, and disagrees by 1.7 standard deviations with calculations that ignore the vacancy. We also determine the energy of the isomeric state to be 30.760(5) keV, a fourfold improvement in precision over the currently accepted value.
Precise β branching-ratio measurement for the 0 + → 0 + superallowed decay of 34 Ar
We have measured the branching ratio for the superallowed 0 + → 0 + β transition from 34 Ar to be 0.9448(8), and determined its ft value to be 3058.1(28) s, a result with ±0.09% precision, which is a factor of three improvement over the previous result based on current world data. The ft-value ratio for the mirror pair of superallowed transitions 34 Ar → 34 Cl and 34 Cl → 34 S, becomes the most precise yet measured and, in a sensitive test of the method used to calculate the isospin-symmetry-breaking correction, δ C , it agrees well with the ratio as calculated with Woods-Saxon radial wave functions. This confirms the method used in the most recent survey of superallowed decays to extract V ud , the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa matrix. Additionally, our branching-ratio results for the four observed Gamow-Teller branches to 1 + states in 34 Cl are shown to agree well with shell-model calculations based on the same effective interactions that were used in the determination of δ C .
New precise half-life measurement for the superallowed β+ emitter Ar34
We have measured the half-life of 34 Ar, the parent of a superallowed 0 + → 0 + β transition, to be 0.84646(35) s. With a precision of 0.04%, this result is an essential ingredient needed to complete a third pair of mirror superallowed transitions, 34 Ar → 34 Cl and 34 Cl → 34 S, the ratio of whose ft values would provide the most sensitive test yet of the isospin-symmetry-breaking corrections used to obtain V ud . In a sequence repeated thousands of times, we implanted a very pure 34 Ar beam into tape for 0.7 s, and then rapidly transported the collected source to a shielded 4π proportional gas counter, which detected the decay positrons from the combined decays of 34 Ar and its daughter 34 Cl. The data were analyzed as a linked parent-daughter pair. Our new result replaces one we published 13 years ago.
Nuclear Data Sheets for A=155
This work represents an update of the previous evaluation of the nuclear data on the A=155 nuclides (2005Re01). The experimental data from reaction and decay studies leading to the following nuclides have been reviewed: {sup 155}La, {sup 155}Ce, {sup 155}Pr, {sup 155}Nd, {sup 155}Pm, {sup 155}Sm, {sup 155}Eu, {sup 155}Gd, {sup 155}Tb, {sup 155}Dy, {sup 155}Ho, {sup 155}Er, {sup 155}Tm, {sup 155}Yb, {sup 155}Lu, {sup 155}Hf, and {sup 155}Ta. These data are presented, together with the adopted level schemes and their properties.
Precise branching ratio measurement for the superallowed β+ decay of 26 Si: Completion of a second mirror pair
As part of a continuing effort to test the unitarity of the Cabbibo-Kobayashi-Maskawa matrix, we have measured the branching ratio for the superallowed 0 + → 0 + β + -decay transition from 26 Si to be 0.7569(14), a result with 0.18% relative precision. With this result, the ft value for the transition is now established with comparable precision to the well-known superallowed transitions currently used in the determination of V ud . Furthermore, it also completes a second pair of mirror superallowed transitions, 26 Si → 26m Al and 26m Al → 26 Mg, the ratio of whose measured ft values provides a sensitive test of the method used to calculate the isospin-symmetry-breaking correction δ C needed to determine V ud . Like the previously measured ratio for the mass-38 mirror pair, the new result agrees well with the calculation based on Woods-Saxon radial wave functions and strengthens the case for rejecting the calculation that uses Hartree-Fock radial functions.
A novel approach to medical radioisotope production using inverse kinematics: A successful production test of the theranostic radionuclide 67Cu
In this work we studied the production of the theranostic radionuclide 67 Cu (t 1/2 =62h) via the reaction of a 70 Zn beam at 15 MeV/nucleon with a hydrogen gas target. The 67 Cu radionuclide, alongside other coproduced isotopes, was collected after the gas target on an Al catcher foil. Radioactivity was measured by offline gamma-ray analysis. After 36h from the end of the irradiation, apart from the product of interest 67Cu, the main radioimpurity coming from the 70 Zn+p reaction was $^{69m}$Zn (t 1/2 =13.8h). Moreover, along with the radionuclide of interest produced in inverse kinematics, the production of additional radioisotopes is possible by making use of the forward-focused neutrons from the reaction and letting them interact with a secondary target. A preliminary test of this concept was realized in the present study. The main requirement to obtain activities appropriate for preclinical studies is the development of high-intensity heavy-ion primary beams.
Nuclear Data Sheets for A=140☆
The 2006 evaluation of A=140 was updated using experimental results published before November 2018 from the various reaction and decay studies leading to the nuclei {sup 140}Sb, {sup 140}Te, {sup 140}I, {sup 140}Xe, {sup 140}Cs, {sup 140}Ba, {sup 140}La, {sup 140}Ce, {sup 140}Pr, {sup 140}Nd, {sup 140}Pm, {sup 140}Sm, {sup 140}Eu, {sup 140}Gd, {sup 140}Tb, {sup 140}Dy, {sup 140}Ho. These data are summarized and presented, together with adopted level schemes and properties.
Precise measurement of α K and α T for the 39.8-keV E 3 transition in Rh 103 : Test of internal-conversion theory
Neutron-activated sources of 103 Ru and 103 Pd both share the isomeric first-excited state in 103 Rh as a daughter product. From independent measurements of both decays, we have measured the K shell and total internal-conversion coefficients, α K and α T , for the 39.8-keV E3 transition, which de-excites that state in 103 Rh, to be 141.1(23) and 1428(13), respectively. When compared with Dirac-Fock calculations, our new results disagree with the version of the theory that ignores the K-shell atomic vacancy, which is consistent with our conclusion drawn from a series of measurements on high multipolarity transitions in nuclei with higher Z. Calculations that include the atomic vacancy indicate that the transition actually has a small M4 component with mixing ratio δ = 0.023(5).
Nuclear Data Sheets for A=158
The experimental results published before February 2017 from the various reaction and decay studies leading to nuclides {sup 158}Nd, {sup 158}Pm, {sup 158}Sm, {sup 158}Eu, {sup 158}Gd, {sup 158}Tb, {sup 158}Dy, {sup 158}Ho, {sup 158}Er, {sup 158}Tm, {sup 158}Yb, {sup 158}Lu, {sup 158}Hf, {sup 158}Ta, {sup 158}W in the A=158 mass chain have been reviewed. These data are summarized and presented, together with adopted level schemes and properties. Large sections of the mass chain are almost identical to the ones in the previous 2004He05 NDS publication by R.G. Helmer.