Search NASA⌕ Search

SEARCH · Search NASA

Results for “ALPHA DECAY RADIOISOTOPES”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

{sup 149}Sm(n,{alpha}){sup 146}Nd Cross Sections in the MeV Region

We have measured the {sup 149}Sm(n,{alpha}){sup 146}Nd cross section at 4.5, 5.0, 5.5, 6.0, and 6.5 MeV. Measurements were performed at the 4.5 MV Van de Graaff accelerator of Peking University with monoenergetic neutrons produced via the {sup 2}H(d,n){sup 3}He reaction using a deuterium gas target. Alpha particles were detected with a double-section gridded ionization chamber having two back-to-back {sup 149}Sm{sub 2}O{sub 3} samples attached to the common cathode. Absolute neutron flux was measured using a small {sup 238}U fission chamber and monitored by a BF{sub 3} long counter. These are the first reported cross sections for this reaction at these energies, except at 6.0 eV, where our new data are in good agreement with our earlier result. The present results help to much better constrain the {sup 149}Sm(n,{alpha}){sup 146}Nd cross section in a region where its energy dependence is changing fairly rapidly and there are large differences between evaluated nuclear data libraries.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2015

Measurement of Actinides in Molybdenum-99 Solution Analytical Procedure

This document is a companion report to a previous report, PNNL 24519, Measurement of Actinides in Molybdenum-99 Solution, A Brief Review of the Literature, August 2015. In this companion report, we report a fast, accurate, newly developed analytical method for measurement of trace alpha-emitting actinide elements in commercial high-activity molybdenum-99 solution. Molybdenum-99 is widely used to produce 99m Tc for medical imaging. Because it is used as a radiopharmaceutical, its purity must be proven to be extremely high, particularly for the alpha emitting actinides. The sample of 99 Mo solution is measured into a vessel (such as a polyethylene centrifuge tube) and acidified with dilute nitric acid. A gadolinium carrier is added (50 µg). Tracers and spikes are added as necessary. Then the solution is made strongly basic with ammonium hydroxide, which causes the gadolinium carrier to precipitate as hydrous Gd(OH) 3 . The precipitate of Gd(OH) 3 carries all of the actinide elements. The suspension of gadolinium hydroxide is then passed through a membrane filter to make a counting mount suitable for direct alpha spectrometry. The high-activity 99 Mo and 99m Tc pass through the membrane filter and are separated from the alpha emitters. The gadolinium hydroxide, carrying any trace actinide elements that might be present in the sample, forms a thin, uniform cake on the surface of the membrane filter. The filter cake is first washed with dilute ammonium hydroxide to push the last traces of molybdate through, then with water. The filter is then mounted on a stainless steel counting disk. Finally, the alpha emitting actinide elements are measured by alpha spectrometry.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2011

Nuclear Data Sheets for A = 249

The evaluated spectroscopic data are presented for known nuclides of mass 249 (Cm, Bk, Cf, Es, Fm, Md, No). {sup 249}No has not been identified as yet. Significant amounts of new data have been added since the last evaluation of A=249 nuclides. This work supersedes earlier full evaluations of A=249 published by 1999Ar21.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Fission-Fusion: A new reaction mechanism for nuclear astrophysics based on laser-ion acceleration

We propose to produce neutron-rich nuclei in the range of the astrophysical r-process around the waiting point N = 126 by fissioning a dense laser-accelerated thorium ion bunch in a thorium target (covered by a CH{sub 2} layer), where the light fission fragments of the beam fuse with the light fission fragments of the target. Via the 'hole-boring' mode of laser Radiation Pressure Acceleration using a high-intensity, short pulse laser, very efficiently bunches of {sup 232}Th with solid-state density can be generated from a Th target and a deuterated CD{sub 2} foil, both forming the production target assembly. Laser-accelerated Th ions with about 7 MeV/u will pass through a thin CH{sub 2} layer placed in front of a thicker second Th foil (both forming the reaction target) closely behind the production target and disintegrate into light and heavy fission fragments. In addition, light ions (d,C) from the CD{sub 2} layer of the production target will be accelerated as well, inducing the fission process of {sup 232}Th also in the second Th layer. The laser-accelerated ion bunches with solid-state density, which are about 10{sup 14} times more dense than classically accelerated ion bunches, allow for a high probability that generated fission products can fuse again. The high ion beam density may lead to a strong collective modification of the stopping power, leading to significant range and thus yield enhancement. Using a high-intensity laser as envisaged for the ELI-Nuclear Physics project in Bucharest (ELI-NP), order-of-magnitude estimates promise a fusion yield of about 10{sup 3} ions per laser pulse in the mass range of A = 180-190, thus enabling to approach the r-process waiting point at N = 126.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Investigation of {sup 246}Fm : in-beam spectroscopy at the limits

The structure of {sup 246}Fm has been investigated using in-beam {gamma}-ray spectroscopy. The experiment was performed at the University of Jyvaeskylae using JUROGAM 2 coupled to RITU and GREAT. The {sup 246}Fm nuclei were produced using a 186 MeV beam of {sup 40}Ar impinging on a target of {sup 208}Pb. JUROGAM 2 was fully instrumented with TNT2D digital acquisition cards. The use of digital acquisition cards and a rotating target allowed for unprecedented beam intensities up to 71 particle-nanoamperes for prompt {gamma}-ray spectroscopy. With all these major advances for spectroscopy a rotational band is observed for the first time in {sup 246}Fm and discussed here.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Nuclear Structure at the Extremes; In-beam {gamma}-ray Spectroscopy of {sup 180}Pb

For the first time, the excited states in the extremely neutron-deficient nucleus {sup 180}Pb have been observed in an in-beam {gamma}-ray measurement employing the recoil-decay tagging technique. Deduced level energies follow the trend of prolate intruder band level energies derived from heavier lead isotopes and reflect the persistence of magicity of the closed Z = 82 proton shell when approaching the proton drip line.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Measurement of absolute E2 transition strengths in {sup 176}W: Signatures for a rapid shape change

The X(5) symmetry describes nuclei at the critical point of the shape phase transition from axially deformed rotor nuclei to spherical vibrators. {sup 150}Nd, {sup 152}Sm, and {sup 154}Gd were the first nuclei where the predicted characteristics of the X(5) symmetry were observed. Later it was shown that also {sup 176,178,180}Os can be successfully described with the X(5) symmetry.In the close vicinity of shape phase transitions one expects strongly changing nuclear shapes. In the X(5) region around A = 150 this was observed for nuclei with different neutron numbers, whereas in the X(5) region around A = 180 this is to be expected for different proton numbers. The aim of the work presented here is the confirmation of a rapid shape change for nuclei close to {sup 178}Os. Besides the knowledge on the level scheme of the nuclei of interest, especially absolute E2 transition strengths are crucial for the interpretation of nuclear structure. Prolate deformation is expected for {sup 176}W. Thus we performed a recoil distance Doppler shift (RDDS) measurement on {sup 176}W to measure E2 transition strengths from level lifetimes. The experiment was performed at the Cologne FN TANDEM accelerator with the Cologne coincidence plunger with the reaction {sup 169}Dy({sup 16}O,4n){sup 176}W and a beam energy of 80 MeV. We will present our experimental results and relate them to data on the neighboring nuclei {sup 178}Os and {sup 182}Pt. The results will be discussed in the framework of nuclear shape transitions in this mass region and compared to calculations with both the Interacting Boson Model (IBM) and the GCM.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Onset of collectivity in Neutron-Rich iron isotopes: Toward a new island of inversion?

The lifetimes of the first excited 2{sup +} states in {sup 62}Fe and {sup 64}Fe have been measured for the first time using the recoil-distance Doppler shift technique, at GANIL. A {sup 238}U beam of 6.5 AMeV impinged on {sup 64}Ni target, and the target like products were slowed down by a degrader foil positioned at micrometer distance downstream of the target and identified in the VAMOS spectrometer on an event-by-event basis. The lifetimes were then determined from the intensities of the degraded and fully Doppler shifted components of the 2{sup +}{yields}0{sup +} transition detected in EXOGAM detectors positioned at backward angles.The resulting lifetimes show a steep increase of the B(E2) values of the first excited 2{sup +} state from {sup 62}Fe to {sup 64}Fe. A comparison with shell model calculations shows that the onset of collectivity is related to the occupation of neutron intruder orbitals. The large B(E2) value for {sup 64}Fe is only reproduced if the valence space includes both the neutron g{sub 9/2} and d{sub 5/2} orbitals. The transition from spherical {sup 68}Ni to more proton-deficient N 40 isotones has some similarity with the island of inversion around {sup 32}Mg. The developing quadrupole collectivity can in both cases be related to the occupation of neutron intruder orbitals which are at the same time quasi-SU(3) partners: (f{sub 7/2}, p{sub 3/2}) for {sup 32}Mg and (g{sub 9/2}, d{sub 5/2}) for the neutron-rich Fe.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Dynamical Dipole Mode in Heavy-Ion Fusion-Evaporation and Fission Reactions in the {sup 192}Pb Mass Region

The prompt {gamma}-ray emission related with the dynamical dipole mode decay was investigated in the {sup 192}Pb mass region by means of the {sup 40}Ca+{sup 152}Sm and {sup 48}Ca+{sup 144}Sm fusion-evaporation and fission reactions at E{sub lab} = 11 and 10.1 MeV/nucleon, respectively. The two reactions populate, through entrance channel having different charge asymmetries, the {sup 192}Pb compound nucleus at an excitation energy of 236 MeV with identical spin distribution. Preliminary results of this experiment show that the dynamical dipole mode survives in collisions involving heavier mass reaction partners than those studied previously. As a fast cooling mechanism on the fusion path, the prompt dipole {gamma} radiation could be of interest for the synthesis of super-heavy elements through ''hot'' fusion reactions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

The {sup 237}Np(n,f) cross section at the CERN n-TOF facility

The {sup 237}Np(n,f) cross sections have been measured at the n-TOF facility relative to the {sup 235}U and {sup 238}U fission cross sections. The n-TOF spallation neutron source at CERN is characterized by a high intensity flux, an excellent time resolution and an extensive neutron energy range (from eV to GeV). A fast ionization chamber was used as a fission fragment detector with efficiency better than 97%. Preliminary {sup 237}Np(n,f) cross sections have been deduced in the energy range from 20 keV to 10 MeV and are found in good agreement with data from literature.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Compton Profile Study of Intermetallic Ti{sub 3}Al

The Compton scattering measurement on intermetallic alloy Ti{sub 3}Al is reported in this work. The measurement is made using 59.54 keV gamma-rays from Am{sup 241} source. Theoretical calculation of Compton profile is also performed employing CRYSTAL code within the framework of density functional theory to compare with the measurement. The theoretical profile of the alloy is also synthesized following the superposition model taking the published Compton profiles of elemental solids from the APW method. The experimental study of charge transfer in the alloys has also been done by performing the experimental Compton profile measurements on Ti and Al following the superposition model and charge transfer from Al to Ti is clearly seen on the alloy formation.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Time Delay in Neutron-Alpha Resonant Scattering

Time delay analysis of neutron-alpha resonant scattering cross sections supports characterization of the lowest 3/2{sup +} level in {sup 5}He as fundamentally an n-{alpha} resonance on the second Riemann energy sheet of both n-{alpha} and deuteron-{sup 3}H channels, with an associated shadow pole on a different unphysical sheet that, through its associated zero on the physical sheet, contributes to the large {sup 4}He(n,d){sup 3}H cross section.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Role of Tensor Force in Light Nuclei Based on the Tensor Optimized Shell Model

We propose a new theoretical approach to describe nucleus using bare nuclear interaction, in which the tensor and short-range correlations are described with the tensor optimized shell model (TOSM) and the unitary correlation operator method (UCOM), respectively. We show the obtained results of He isotopes using TOSM+UCOM, such as the importance of the pn-pair correlated by the tensor force, and the structure differences in the LS partners of 3/2{sup -} and 1/2{sup -} states of {sup 5}He. We also apply TOSM to the analysis of two-neutron halo nucleus {sup 11}Li, on the basis of the ''core described in TOSM''+n+n model. The halo formation of {sup 11}Li is naturally explained, in which the tensor correlation in the {sup 9}Li core is Pauli-blocked on the p-wave neutrons in {sup 11}Li and the s-wave component of halo structure is enhanced.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

{Lambda}* hypernuclei with chiral dynamics

As a strangeness S = -1 and baryon number B = 2 system, the two-body bound state of {Lambda}* = {Lambda}(1405) and a nucleon is studied. To solve the {Lambda}*N system, we construct the {Lambda}*N potential by extending the Juelich model with couplings estimated in the chiral unitary approach. We have the {Lambda}*N quasi-bound state with the mass, M{sub {Lambda}}*N{approx}2366 MeV which is shallowly bound with the binding energy B{approx}9 MeV in terms of the K-barNN system. Decay width of the fall apart process, where the {Lambda}*N resonance decays to {pi}{Sigma}N with a nucleon being as a spectator, is estimated to be {Gamma}{sub F.A}{approx}49 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Measurement of Geo-neutrinos with KamLAND

Radioactive isotopes inside the Earth produce geo-neutrinos through beta decays. Geo-neutrinos could be direct probes to investigate the interior of the Earth as a supplement to the current geophysical survey that mainly relies on an indirect seismic approach. After the Kamioka liquid scintillator antineutrino detector (KamLAND) reported the first indication of geo-neutrinos in 2005, we have accumulated data for a total of 2,135 days of live-time and achieved a lower background level by purifying liquid scintillator. The number of obtained geo-neutrino events is 106{sub -28}{sup +29} corresponding to an electron antineutrino flux of 4.3{sub -1.1}{sup +1.2}x10{sup 6} cm{sup -2} s{sup -1} from {sup 238}U and {sup 232}Th series at the Earth's surface. The null hypothesis for the existence of geo-neutrinos is excluded at the 99.997% confidence level. We combined this precise result with that of the Borexino experiment to obtain 20.0{sub -8.6}{sup +8.8} TW as a contribution of {sup 238}U and {sup 232}Th to the Earth heat flow.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2011

The Concentrations of {sup 40}K, {sup 226}Ra and {sup 232}Th in Soil Sample in Osmaniye (Turkey)

The {sup 40}K, {sup 226}Ra and {sup 232}Th concentration is due to the magmatic structure of the earth and it can be varied from place to place. Osmaniye is located in the Eastern side of Mediteranean Region. It holds the climatic characteristics of the same region and arises with Middle Taurus Mountains from west to North and with Amonos Mounations in East and West-east parts and is situated between 35 deg. .52'-36 deg. .42' east longitudes and 36 deg. .57'-37 deg. .45' north latitudes. In this study, the natural radioactivity concentrations {sup 40}K, {sup 226}Ra and {sup 232}Th in some soil samples collected in Osmaniye have been investigated. The measurements have been performed using 3x3{sup ''} NaI(Tl) detector system.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Natural Radioactivity of Boron Added Clay Samples

Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazard index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

54 ENVIRONMENTAL SCIENCES↗