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18 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Energy calibration of germanium detectors for the Majorana Demonstrator

The Majorana Demonstrator was a search for neutrinoless double-beta decay (0νββ) in the 76 Ge isotope. It was staged at the 4850-foot level of the Sanford Underground Research Facility (SURF) in Lead, SD. The experiment consisted of 58 germanium detectors housed in a low background shield and was calibrated once per week by deploying a 228 Th line source for 1 to 2 hours. The energy scale calibration determination for the detector array was automated using custom analysis tools. We describe the offline procedure for calibration of the Demonstrator germanium detectors, including the simultaneous fitting of multiple spectral peaks, estimation of energy scale uncertainties, and the automation of the calibration procedure.

47 OTHER INSTRUMENTATION↗
DOE OSTI2010

Nuclear Data Sheets for A = 58

The evaluated spectroscopic data are presented for known nuclides of mass 58 (Ca,Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn). Excited-state data are nonexistent for {sup 58}Ca, {sup 58}Sc, and {sup 58}Zn; and very scarce for {sup 58}Ti and {sup 58}V, with only one tentative level in each case. Except for half-lives, no other radioactive decay data are available for the decay of {sup 58}Sc and {sup 58}Ti. The radioactive decays of {sup 58}V, {sup 58}Cr and {sup 58}Zn are not considered as well established. Superdeformed structures are known in {sup 58}Ni (two bands) and in {sup 58}Cu (one band). Prompt proton decay of high-spin states in 58Ni for eight levels and prompt {alpha} decay for two states have been identified. In {sup 58}Cu, one high-spin state decays by prompt proton emission. Very complex high-spin structures are now known for {sup 58}Ni from the work by 2009Jo03.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Special features of single-particle proton spectra of nickel, zinc, and germanium isotopes in the vicinity of the proton drip line

The single-particle proton spectra of the neutron-deficient isotopes {sup 50,52}Ni, {sup 56,58,60,62}Zn, and {sup 60,62,64}Ge were calculated on the basis of the dispersive optical model whose parameters were extrapolated from the region of stable isotopes. The resulting parameter values lead to agreement between the total number of protons in bound states and the charge number Z of the respective nucleus. The results of the calculations are indicative of a weakly magic character of the {sup 58}Zn nucleus, which has a traditional magic number of N = 28 and a nearly magic number of Z = 30, and the {sup 64}Ge nucleus, for which N = Z = 32.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Measurement of the 70 Ge( d , n ) 71 As cross section from 2.1 MeV to 10 MeV

This work reports experimental 70 Ge(d,n) 71 As cross sections producing Arsenic-71 (t 1/2 = 65.3 h, 28% β + ), a potentially useful diagnostic radionuclide. Target stacks containing two nat Ge foils, a nat Ni monitor foil, and an Al degrader were irradiated with 5.5–10 MeV deuterons using an FN Tandem Van de Graaff accelerator. 71 As and 61 Cu, 56 Co, and 58 Co (from nat Ni(d,x)) were quantified in the foils by high purity germanium gamma spectrometry. Furthermore, the measured cross sections are larger than previously reported and suitable for producing preclinical quantities of diagnostic radiopharmaceuticals.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2014

Nuclear Data Sheets for A = 54

The 2005 evaluation for A=54 (2006Hu08) has been updated. Detailed experimental nuclear structure data and decay data for all nuclei with mass chain A=54 are presented in this current evaluation. The new data and information are given in following datasets: {sup 54}Ca: {sup 9}Be({sup 76}Ge, X) and Be({sup 55}Sc, p), ({sup 56}Ti, 2p) {sup 54}Sc: {sup 54}Ca β{sup −} decay and {sup 54}Sc IT decay {sup 54}Ti: {sup 54}Sc β{sup −} decay {sup 54}Cr: {sup 54}Mn ε decay, {sup 56}Fe(μ, nupng), and {sup 238}U({sup 64}Ni, Xγ) {sup 54}Mn: {sup 51}V({sup 20}Ne, Xγ), {sup 55}Mn(p, pn), and {sup 56}Fe(μ, nu2ng) {sup 54}Fe: {sup 58}Ni α decay, {sup 9}Be({sup 55}Co, Xγ), {sup 54}Fe(e, e'), {sup 54}Fe(p, p'), and Coulomb Excitation {sup 54}Co: {sup 54}Ni ε decay, {sup 55}Cu εp decay, {sup 28}Si({sup 32}S, αpnγ), {sup 54}Fe(p,n), and {sup 54}Fe({sup 3}He, t) {sup 54}Ni: {sup 54}Ni IT decay, {sup 55}Zn εp decay, {sup 9}Be({sup 55}Ni, Xγ), and {sup 24}Mg({sup 32}S, Xγ) {sup 54}Zn: Ni({sup 58}Ni, X)

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Pressure-induced superconductivity in a novel germanium allotrope

High-pressure studies on elements play an essential role in superconductivity research, with implications for both fundamental science and applications. Here we report the experimental discovery of surprisingly low pressure driving a novel germanium allotrope into a superconducting state in comparison to that for α-Ge. Raman measurements revealed structural phase transitions and possible electronic topological transitions under pressure up to 58 GPa. Based on pressure-dependent resistivity measurements, superconductivity was induced above 2 GPa and the maximum T c of 6.8 K was observed under 4.6 GPa. Interestingly, a superconductivity enhancement was discovered during decompression, indicating the possibility of maintaining pressure-induced superconductivity at ambient pressure with better superconducting performance. Density functional theory analysis further suggested that the electronic structure of Ge (oP32) is sensitive to its detailed geometry and revealed that disorder in the β-tin structure leads to a higher T c in comparison to the perfect β-tin Ge.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Electron capture decay of 58-min U-229(92) and levels in Pa-229(91)

Electron capture decay of U-229 is investigated by measuring the gamma-ray and conversion electron spectra of mass-separated and unseparated U-229 sources with high-resolution germanium and silicon detectors, respectively. Gamma-gamma coincidence measurements are also performed using germanium detectors. These studies provide level energies and level ordering in Pa-229. Single-particle assignments are given to these levels which are in agreement with the systematics in this region and also with theory. In a previous study, we report the observation of a 5/2(+/-) parity doublet in the Pa-229 ground state, which is a signature of octupole deformation. The present analysis of the data still shows a splitting of 60 +/- 50 eV, but with this large uncertainty the existence of the doublet is not certain.

Ahmad, I.↗
DOE OSTI2025

Recovery and Refining of Rare Earth Elements from Lignite Mine Wastes

The University of North Dakota (UND), in collaboration with a comprehensive team of technical, business and host-site partners, built on prior technology development to complete a front-end engineering and design (FEED) and business planning study to recover and refine rare earth elements (REE) and critical minerals (CM) from North Dakota (ND) lignite mine wastes. The end of project goal was to have an investment quality project and a committed team ready to commercialize the proposed technologies in a future construction and operations phase.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2019

Nickle Concentration Effect on Low Magnetic Field Magnetocaloric Properties for Ni{sub 2+x}Mn{sub 1−x}Ge

Low magnetic field magnetocaloric properties of Ni{sub 2+x}Mn{sub 1−x}Ge near phase transition from a ferromagnetic to a paramagnetic state were investigated theoretically for level of doping x = 0.1 and 0.2. It is shown that the change of Ni content allows the magnetocaloric effect in Ni{sub 2+x}Mn{sub 1−x}Ge to be tunable, which is more practical for construction magnetocaloric refrigeration. Furthermore, the results show that the magnetocaloric properties of Ni{sub 2+x}Mn{sub 1−x}Ge samples are significantly larger and comparable with some magnetocaloric properties of many materials like La{sub 1−x}Cd{sub x}MnO{sub 3}, Gd{sub 1−x}Ca{sub x}BaCo{sub 2}O{sub 5.5}, Ge{sub 0.95}Mn{sub 0.05}, La{sub 1.25}Sr{sub 0.75}MnCoO{sub 6}, Ni{sub 58}Fe{sub 26}Ga{sub 28}, and MnAs films.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Combinatorial Platform for Discovery of Nanocrystal-Ink Based Earth Abundant Element PV with Efficiency Greater than 20% (Final Technical Report)

(1) We successfully developed an ultrasonic spray coating system that can be used to deposit thin chalcogenide films with composition gradients. 4 publications under the contract have been published with the instrument. The instrument was used to reveal the effects of intrinsic composition and examine the effects of 25 different dopant elements. Surprisingly, doping with most elements had little to no effect on the quasi- Fermi level splitting of bare films. A few elements were found to be detrimental including Fe, Co, and Ni. However, Li, Ge, and others were discovered to be beneficial. Ge and Li were explored in depth, and our best devices utilize lithium doping. (2) We developed a new model of absorption coefficients, that when combined with absolute intensity photoluminescence, yield the steady-state quasi-Fermi level splitting and a way to quantify the sub-bandgap absorption. This has resulted in 2 publications on the method, with another in preparation. This is a significant development that should impact other PV technologies. We have already received samples from 2 major PV companies to examine. Further, the model shows that tail states (potential fluctuations) in CZTSSe can only explain about 90 mV of loss in the open circuit voltage. (3) We found that lithium doping has several beneficial effects on CZTSSe. It improves the open-circuit voltage, short circuit current, fill factor, and shunt resistance. By using scanning Kelvin probe microscopy (SKPM) and conductive AFM (along with device measurements, DLPC, and XPS), we discovered that lithium acts to increase the p-type doping in both the grain and grain boundaries (GBs). The effect is stronger in the GBs and changes the direction of the electric field at the GB. In lithium doped devices, an electric field repels minority carrier electrons away from the GB. This resulted in a publication and the fabrication of 11.8% efficient devices from a DMSO-thiourea molecular ink. The mechanism of action is most likely due to the formation of Li Cu , which inhibits the formation of the donor defect Zn Cu . This reduces compensation and increases the net p-type doping. (4) By alloying with germanium, we have fabricated CZTGSSSe devices with the best open-circuit voltage (relative the maximum theoretical open-circuit voltage for the bandgap) for any kesterite solar cell. The Voc/Voc,max is 63%, compared to 58% for the record efficiency cell from hydrazine. The origin of the increased voltage efficiency appears to be related to the conduction band off-set and the suppression of a deep defect ($\sim$0.8 eV), most likely due to Cu Sn , but Sn Zn or Sn Cu are also possible. All milestones and go/no-go metrics were met with exception of the device efficiency milestone (15% then 20%). However, under the contract, hydrazine-free CZTSSe device efficiencies increased from 7.2% at the start of the contract to 11.8% upon completion.

14 SOLAR ENERGY↗
DOE OSTI2017

Combinatorial Platform for Discovery of Nanocrystal-Ink Based Earth Abundant Element PV with Efficiency Greater than 20%

(1) We successfully developed an ultrasonic spray coating system that can be used to deposit thin chalcogenide films with composition gradients. 4 publications under the contract have been published with the instrument. The instrument was used to reveal the effects of intrinsic composition and examine the effects of 25 different dopant elements. Surprisingly, doping with most elements had little to no effect on the quasi-Fermi level splitting of bare films. Ge and Li were explored in depth, and our best devices utilize lithium doping. (2) We developed a new model of absorption coefficients, that when combined with absolute intensity photoluminescence, yield the steady-state quasi-Fermi level splitting and a way to quantify the sub-bandgap absorption. This has resulted in 2 publications on the method, with another in preparation. This is a significant development that should impact other PV technologies. (3) We found that lithium doping has several beneficial effects on CZTSSe. It improves the open-circuit voltage, short circuit current, fill factor, and shunt resistance. By using scanning Kelvin probe microscopy (SKPM) and conductive AFM (along with device measurements, DLPC, and XPS), we discovered that lithium acts to increase the p-type doping in both the grain and grain boundaries (GBs). The effect is stronger in the GBs and changes the direction of the electric field at the GB. In lithium doped devices, an electric field repels minority carrier electrons away from the GB. This resulted in a publication and the fabrication of 11.8% efficient devices from a DMSO-thiourea molecular ink. The mechanism of action is most likely due to the formation of LiCu, which inhibits the formation of the donor defect ZnCu. This reduces compensation and increases the net p-type doping. (4) By alloying with germanium, we have fabricated CZTGSSe devices with the best open-circuit voltage (relative the maximum theoretical open-circuit voltage for the bandgap) for any kesterite solar cell. The Voc/Voc,max is 63%, compared to 58% for the record efficiency cell from hydrazine. The origin of the increased voltage efficiency appears to be related to the conduction band off-set and the suppression of a deep defect (~0.8 eV), most likely due to CuSn, but SnZn or SnCu are also possible. All milestones and go/no-go metrics were met with exception of the device efficiency milestone (15% then 20%). However, under the contract, hydrazine-free CZTSSe device efficiencies increased from 7.2% at the start of the contract to 11.8% upon completion.

14 SOLAR ENERGY↗
DOE OSTI2010

Observation of new neutron-rich isotopes at the NSCL

Recently, increased primary beam intensities at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University and advances in experimental techniques allowed probing further into unknown regions of the table of the isotopes with fragmentation and in-flight fission reactions. Recent measurements at the NSCL have demonstrated that primary beams of {sup 48}Ca at 141 MeV/u and {sup 76}Ge at 132 MeV/u can be used to produce new isotopes {sup 40}Mg, {sup 42,43}Al, {sup 44}Si, {sup 52}Ar, {sup 50}Cl, {sup 52,53}Ar, {sup 55,56}K, {sup 57,58}Ca, {sup 59,60,61}Sc, {sup 62,63}Ti, {sup 65,66}V, {sup 68}Cr, {sup 70}Mn in the proximity of the neutron dripline. Also, experiments with {sup 238}U(81 MeV/u) and {sup 208}Pb(86 MeV/u) beams in order to measure production yields and possibly observe several neutron rich isotopes in the first time have recently been performed at the NSCL. A search for new neutron-rich isotopes with {sup 48}Ca and {sup 76}Ge beams was carried out using the recently developed two-stage fragment separator technique.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2025

Deuteron-induced reactions on natural Zr from threshold to 50 MeV: production of 86g Y

Two stacks of thin Zr foils were irradiated with 30 and 50 MeV deuterons, respectively, using the Lawrence Berkeley National Laboratory 88-Inch Cyclotron, and 19 excitation functions for nat Zr(d,x) reactions were measured over a beam energy range of 6.3–47.64 MeV, where the independent cross sections for nat Zr(d,x) 88 Nb and nat Zr(d,x) 86m,g Y were measured for the first time. The well-characterized nat Fe(d,x) 56 Co, nat Ni(d,x) 56 Co, nat Ni(d,x) 58 Co, nat Ni(d,x) 61 Cu, nat Ti(d,x) 46 Sc and nat Ti(d,x) 48 V monitor reactions were used to determine the deuteron beam current throughout the stacks. All cross sections were determined using High Purity Germanium (HPGe) detector γ-ray spectroscopy. A variance minimization technique was employed to simultaneously constrain the deuteron beam currents with multiple monitor reactions, thus reducing systematic uncertainties. An additional 16 channels are reported for reactions on the nickel, titanium, and iron monitor foils, leading to a total of 35 excitation functions, with seven reaction channels reported for the first time in this work. The measured excitation functions are compared to calculations provided by the reaction modeling codes TALYS – 2.0, ALICE – 2020, CoH – 3.5.3 and EMPIRE – 3.2.3, as well as the TENDL – 2023 data library. The degree of agreement between theory and experiments is discussed. The possible production of the important PET radionuclide 86g Y via the nat Zr(d,x) route was critically examined. The physical yields for nat Zr(d,x) 86 Y and other yttrium isotopes produced were calculated and compared to other production pathways. Due to high-level of associated radionuclide impurities, this route cannot deliver 86g Y suitable for medical applications.

86gY↗
DOE OSTI2018

Patient Radiation Dose Reduction Considerations in a Contemporary Interventional Radiology Suite

PurposeWe sought to evaluate patient radiation exposure during complex liver interventional procedures performed with newer angiography equipment.Materials and MethodsWe conducted a retrospective study of transjugular intrahepatic portosystemic shunt (TIPS) creations and liver tumor embolizations performed in our new angiography suite (Discovery IGS740, GE Healthcare). T tests were used to compare air kerma-area product (P{sub KA}) and reference plane air kerma (K{sub a,r}) in the new room versus data from historical rooms and previous studies (including the RAD IR study). Results were expressed as medians [interquartile ranges (Q1, Q3)].ResultsFrom February 2015 to June 2016, 134 complex liver interventional procedures were performed in the new room, including 14 TIPS creations, 60 hepatic tumor arterial embolizations (HAEs), 26 Y90 mappings (Y90m), and 34 Y90 radioembolizations (Y90). K{sub a,r} (Gy) values were as follows: TIPS, 0.65 (0.24, 1.15); HAE, 0.89 (0.49, 1.49); Y90m, 0.54 (0.38, 0.94); Y90, 0.46 (0.21, 1.06). P{sub KA} (Gy·cm{sup 2}) values were as follows: TIPS, 148.2 (66.7, 326.5); HAE, 142.6 (88, 217.8); Y90m, 148.3 (98.2, 247); Y90, 90.8 (43.9, 161.5). K{sub a,r} and P{sub KA} were lower in the new room than in historical rooms [K{sub a,r} and P{sub KA} reductions: TIPS, 58 and 49%; HAE, 31 and 39%; Y90m, 58 and 52%; Y90, 49 and 56% (p < 0.05)] and versus the RAD IR study [K{sub a,r} and P{sub KA} reductions: TIPS, 64 and 43%; HAE, 26 and 40% (p < 0.05)].ConclusionsUsing the latest technology and image processing tools enables significant reduction in radiation exposure during complex liver interventional procedures.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2022

Ultrahigh-pressure disordered eight-coordinated phase of Mg 2 GeO 4 : Analogue for super-Earth mantles

Mg 2 GeO 4 is important as an analog for the ultrahigh-pressure behavior of Mg 2 SiO 4 , a major component of planetary interiors. In this study, we have investigated magnesium germanate to 275 GPa and over 2,000 K using a laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction and density functional theory (DFT) computations. The experimental results are consistent with the formation of a phase with disordered Mg and Ge, in which germanium adopts eightfold coordination with oxygen: the cubic, Th 3 P 4 -type structure. DFT computations suggest partial Mg-Ge order, resulting in a tetragonal $I\bar{4}2d$ structure indistinguishable from $I\bar{4}3d$ Th 3 P 4 in our experiments. If applicable to silicates, the formation of this highly coordinated and intrinsically disordered phase may have important implications for the interior mineralogy of large, rocky extrasolar planets.

58 GEOSCIENCES↗
DOE OSTI2016

Investigations on the structure of Pb-Ge-Se glasses

Chalcogenide glasses have attracted much attention because of their potential application in various solid state devices. In the present work, we report here the detailed thermal, structural, microstructural studies on Pb{sub x}Ge{sub 42-x}Se{sub 58} with (0 ≤ x ≤ 20) glasses. The influence of Pb content on the glass transition temperature, specific heat, and non-reversing enthalpy is observed and discussed qualitatively The Raman spectroscopic studies on the all the glass compositions are carried out and deconvoluted into different structural units. The positron annihilation life-time spectroscopy (PALS) studies helped to understand the nature of defect states present in the glassy system and its variation with Pb content. The concentration of charged defect centers is found to increase, whereas the open volume defect concentration decreases with Pb content in these glasses.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

The Second-phase Development of the China JinPing Underground Laboratory

During 2013-2015 an expansion of the China JinPing underground Laboratory (CJPL) will be undertaken along a main branch of a bypass tunnel in the JinPing tunnel complex. This second phase of CJPL will increase laboratory space to approximately 96,000 m 3 , which can be compared to the existing CJPL-I volume of ∼ 4,000 m 3 . One design configuration has eight additional hall spaces, each over 60 m long and approximately12 m in width, with overburdens of about 2.4 km of rock, oriented parallel to and away from the main water transport and auto traffic tunnels. There are additional possibilities for further expansions at a nearby second bypass tunnel and along the entrance and exit branches of both bypass tunnels, potentially leading to an expanded CJPL comparable in size to Gran Sasso. Concurrent with the excavation activities, planning is underway for dark matter and other rare- event detectors, as well as for geophysics/engineering and other coupled multi-disciplinary sensors. In the town meeting on 8 September, 2013 at Asilomar, CA, associated with the 13 th International Conference on Topics in Astroparticle and Underground Physics (TAUP), presentations and panel discussions addressed plans for one-ton expansions of the current CJPL germanium detector array of the China Darkmatter EXperiment (CDEX) collaboration and of the duel-phase xenon detector of the Panda-X collaboration, as well as possible new detector initiatives for dark matter studies, low-energy solar neutrino detection, neutrinoless double beta searches, and geoneutrinos. JinPing was also discussed as a site for a low-energy nuclear astrophysics accelerator. Geophysics/engineering opportunities include acoustic and micro-seismic monitoring of rock bursts during and after excavation, coupled-process in situ measurements, local, regional, and global monitoring of seismically induced radon emission, and electromagnetic signals. Additional ideas and projects will likely be developed in the next few years, driven by China’s domestic needs and by international experiments requiring access to very great depths.

58 GEOSCIENCES↗
DOE OSTI2010

New subshell closure at N=58 emerging in neutron-rich nuclei beyond {sup 78}Ni

The structure of neutron-rich nuclei beyond {sup 78}Ni was studied using postaccelerated radioactive beams of {sup 83,84,85}Ga utilizing beta gamma and beta-n gamma spectroscopy. Our data, when combined with energy level systematics, suggests a possible new spherical subshell closure at N=58 is created by the nearly degenerated nu3s{sub 1/2} and nu2d{sub 5/2} orbitals being well separated from other orbitals above N=50. The near degeneracy of these states could be evidenced by isomerism in this region. The energies of the 2{sub 1}{sup +} and proposed 4{sub 1}{sup +} states observed in N=52 {sup 84}Ge are interpreted as an indication of a possible weakening of the doubly magic {sup 78}Ni core for nuclei beyond N=50. The experimental evidence is supported by spherical HFB calculations using the SkO{sub T} functional involving the tensor term in the nucleon-nucleon interaction.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗