A new isobar separator, LSTAR (Light-ion guide Separator for Texas A&M's Radioactive ion beams), has been designed to purify the exotic beams produced by a He-driven light-ion guide (He-LIG) system at Texas A&M University, primarily for the TAMUTRAP experiment. The main purpose of TAMUTRAP is to probe for physics beyond the standard model by searching for possible scalar or tensor currents in the weak interaction using nuclear beta decay. The proton-rich isotopes of interest for this program will be produced at low yields, requiring efficient reduction of contaminant species to avoid overloading of TAMUTRAP's radiofrequency quadrupole cooler-buncher. The layout, ion-optics, and specifications of LSTAR will be presented.

For many fission products, the $\ensuremath{\gamma}$ rays emitted following $\ensuremath{\beta}$ decay provide an easily detectable signature that can be used to identify their quantities and distributions in a sample. As a result, $\ensuremath{\gamma}$-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the $\ensuremath{\gamma}$-ray intensities is available. In many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. In this paper, we present high-precision results for the absolute $\ensuremath{\gamma}$-ray emission intensities for the most intense transitions in the $\ensuremath{\beta}$ decays of $^{144}\mathrm{Ce}$ and $^{147}\mathrm{Nd}$. We measured these intensities to $\ensuremath{\lesssim}1%$ accuracy by producing radiopure samples with fission-product beams at CARIBU and detecting the emitted radiation with a $4\ensuremath{\pi}\ensuremath{\beta}$ counter and a meticulously efficiency-calibrated high purity germanium detector at Texas A University.

For many fission products, the gamma rays emitted following beta decay provide an easily detectable signature that can be used to identify their quantities and distributions in a sample. As a result, gamma-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the gamma-ray intensities is available. In many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. In this paper, we present high-precision results for the absolute gamma-ray emission intensities for the most intense transitions in the beta decays of Ce-144 and (147) Nd. We measured these intensities to less than or similar to 1% accuracy by producing radiopure samples with fission-product beams at CARIBU and detecting the emitted radiation with a 4 pi beta counter and a meticulously efficiency-calibrated high purity germanium detector at Texas A&M University.

A new 3He-driven IGISOL production station and mass separator have been designed to produce neutron-deficient low-mass isotopes at the Cyclotron Institute for the TAMUTRAP facility. The LSTAR design has a mass resolution M/ΔM≥3,000 to reject contaminants with >95% efficiency.

The reaction of a 100Mo beam at 12 MeV/nucleon impinging on a 4He gas-cell target was performed. The 99Mo alongside other coproduced isotopes were collected after the gas target on an aluminum catcher foil and their respective radioactivities were measured by offline γ-ray analysis. In this contribution, preliminary experimental results which are used to discuss the possibility of optimal large-scale production conditions of the produced radioisotopes are presented.

For many fission products, the γ rays emitted following β decay provide an easily-detectable signature that can be used to identify their quantities and distributions in a sample. As a result, γ-ray spectroscopy is often exploited to study fission-product yields, provided sufficiently accurate information on the γ-ray intensity is available. However, in many cases, the uncertainties in the existing nuclear data are large enough that they compromise the precision achievable for modern experiments and applications. To address this need, we have developed a new experimental method that is well suited to precisely measure absolute γ-ray intensities in the β decay of long-lived fission products. The approach involves the production of a radiopure sample by implantation of a mass-separated ion beam from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) facility on a thin carbon foil. The emitted β-decay radiation is detected with a 4π gas proportional counter and a meticulously efficiency-calibrated high-purity germanium (HPGe) detector. As a first measurement to demonstrate the approach, we studied the absolute γ-ray intensities of the strongest transitions following the β decay of 95Zr and its decay-daughter 95Nb, and determined them to fractional precisions of better than 1–2%. In addition, with a larger sample of activity produced through neutron irradiation of an isotopically-enriched Zr foil, we performed a high-precision measurement of the relative γ-ray intensities following the decay of 95Zr with just the HPGe detector. The sample-production method at CARIBU and the coincidence detection approach demonstrated here can be applied to study fission products with half-lives longer than a day, which includes isotopes important not only for nuclear-energy and national-security applications, but also for medical-isotope research and environmental monitoring.

The Texas A&M University Penning Trap (TAMUTRAP) facility aims to test the standard model of the electroweak interaction by measuring the beta-v correlation parameter, alpha(beta v), for beta-delayed proton emitters in the atomic mass range 20 < A < 40. Precision measurements of this correlation parameter and, inextricably, the Fierz interference parameter, are a sensitive probe of physics beyond the standard model. Using off-line ion sources, the TAMUTRAP facility has been commissioned by demonstrating the ability to manipulate the trapped-ion motions as well as to perform precision mass measurements. Our novel cylindrical Penning trap - the world's largest - differs from typical designs in two key aspects: the electrode structure has an 180-mm inner diameter and an overall length of 334.89 mm leading to a uniquely small length/radius ratio l/r = 3.72; and we do not use the long end cap approximation, instead our short endcap electrodes are closed and capable of being placed at an arbitrary potential. This geometry is optimized for observing beta-delayed proton decays, but is also well suited for other in-trap and post-trap precision decay experiments. In addition to presenting an overview of the TAMUTRAP facility, we demonstrate that our unique Penning trap is able to measure masses with a precision similar to typical trap designs. (C) 2021 Elsevier B.V. All rights reserved.

The inverse kinematics methodology using a gas target has been applied to produce medically important radionuclides at the Cyclotron Institute at Texas A&M University. The production of the theranostic radionuclide 67 Cu (T1/2 = 62 h) through the reaction of a 70 Zn beam at 15 MeV/nucleon with a hydrogen gas target was performed. The activities at end of irradiation and the thick target yield were obtained for 67 Cu. A test using the forward-focused neutrons from the primary reaction to irradiate nat Zn to produce 67 Cu is also presented.

Continuing with our effort of precisely measuring the branching ratios for long-lived fission products we have collected and measured two radiopure ¹⁵⁶Eu samples. The samples were collected on thin (40 μg/cm²) carbon-foil backings using a low-energy mass-separated beam of A = 156 fission products from CARIBU at Argonne National Laboratory. During collection, a HPGe detector was used to continuously monitor the implantation rate by detecting the characteristic γ rays emitted following the β decay of the shorter-lived fission products. The first sample had measured activity of 375 Bq while the second one had an activity of 700 Bq. The implanted samples were then shipped to Texas A&M University for measurement of the subsequent decay.

The predominant branch in the $\ensuremath{\beta}$ decay of $^{34}\mathrm{Ar}$ is the superallowed ${0}^{+}\ensuremath{\rightarrow}\phantom{\rule{0.16em}{0ex}}{0}^{+}$ transition to the ground state of $^{34}\mathrm{Cl}$. To determine its important branching ratio one must first establish the ratios for the competing Gamow-Teller branches based on the measured intensities of $\ensuremath{\gamma}$ rays subsequently emitted from the excited states they populate in $^{34}\mathrm{Cl}$. The strongest of these branches populates the ${1}^{+}$ state at 666 keV in $^{34}\mathrm{Cl}$, which has three possible $\ensuremath{\gamma}$-decay paths. We report here a measurement of the decay of this state, which we populated via resonant proton capture in the reaction $^{33}\mathrm{S}$($p,\ensuremath{\gamma}$)$^{34}\mathrm{Cl}$. We find that the intensity of the 519-keV $\ensuremath{\gamma}$-ray path is 1.46(19)% relative to that of the 666-keV path. This result is critical to new precise measurements of the superallowed decay of $^{34}\mathrm{Ar}$.

The predominant branch in the beta decay of Ar-34 is the superallowed 0(+) -> 0(+) transition to the ground state of Cl-34. To determine its important branching ratio one must first establish the ratios for the competing Gamow-Teller branches based on the measured intensities of gamma rays subsequently emitted from the excited states they populate in Cl-34. The strongest of these branches populates the 1+ state at 666 keV in Cl-34, which has three possible gamma-decay paths. We report here a measurement of the decay of this state, which we populated via resonant proton capture in the reaction S-33(p,gamma)Cl-34. We find that the intensity of the 519-keV gamma-ray path is 1.46(19)% relative to that of the 666-keV path. This result is critical to new precise measurements of the superallowed decay of 34Ar.

We have measured the half-life of Ar-34, the parent of a superallowed 0(+) -> 0(+) beta 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, Ar-34 -> Cl-34 and Cl-34 -> S-34, 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 Ar-34 beam into tape for 0.7 s, and then rapidly transported the collected source to a shielded 4 pi proportional gas counter, which detected the decay positrons from the combined decays of Ar-34 and its daughter Cl-34. The data were analyzed as a linked parent-daughter pair. Our new result replaces one we published 13 years ago.

The 30.8 keV (1/2)(-) isomeric state in Nb-93(41) decays by an M4 transition to the (9/2) (+) ground state. We have measured the K-]shell internal conversion coefficient alpha 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 alpha(K) . Taking the fluorescence yield of niobium to be 0.751(4), we obtain alpha(K) = 2 .56(9) x 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.

We have measured the branching ratio for the superallowed 0(+) -> 0(+) beta transition from Ar-34 to be 0.9448(8), and determined its f t value to be 3058.1(28) s, a result with +/- 0.09% precision, which is a factor of 3 improvement over the previous result based on current world data. The f t-value ratio for the mirror pair of superallowed transitions Ar-34 -> Cl-34 and Cl-34 -> S-34 becomes the most precise yet measured and, in a sensitive test of the method used to calculate the isospin-symmetry-breaking correction, delta(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 Vud, the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa matrix. In addition, our branching-ratio results for the four observed Gamow-Teller branches to 1(+) states in Cl-34 are shown to agree well with shell-model calculations based on the same effective interactions that were used in the determination of delta(C).