D. W. Stracener

• Oak Ridge National Laboratory

A segmented-scintillator-based implantation detector was developed to study the energy distribution of beta-delayed neutrons emitted from exotic isotopes. The detector comprises a 34 $\times$ 34 YSO scintillator coupled to an 8 $\times$ 8 Position-Sensitive Photo-Multiplier Tube (PSPMT) via a tapered light guide. The detector was used at RIBF, RIKE...

β-delayed γ-neutron spectroscopy has been performed on the decay of A=84 to 87 gallium isotopes at the RI-beam Factory at the RIKEN Nishina Center using a high-efficiency array of He3 neutron counters (BRIKEN). β−2n−γ events were measured in the decays of all of the four isotopes for the first time, which is direct evidence for populating the excit...

{65}$Zn is a common calibration source, moreover used as a radioactive tracer in medical and biological studies. In many cases, $\gamma$-spectroscopy is a preferred method of $^{65}$Zn standardization, which relies directly on the branching ratio of $J \pi (^{65}\text{Zn} ) = 5/2^- \rightarrow J \pi (^{65}\text{Cu}) = 5/2^- $ via electron capture (...

Potassium-40 is a widespread, naturally occurring isotope whose radioactivity impacts estimated geological ages spanning billions of years, nuclear structure theory, and subatomic rare-event searches—including those for dark matter and neutrinoless double-beta decay. The decays of this long-lived isotope must be precisely known for its use as a geo...

Potassium-40 is a widespread, naturally occurring isotope whose radioactivity impacts subatomic rare-event searches, nuclear structure theory, and estimated geological ages. A predicted electron-capture decay directly to the ground state of argon-40 has never been observed. The KDK (potassium decay) collaboration reports strong evidence of this rar...

Background: The β decays of fission products produced in nuclear fuel are important for nuclear energy applications and fundamental science of reactor antineutrinos. In particular, nuclear reactor safety is related to the decay modes of radioactive neutron-rich nuclei, primarily via the emission of γ rays, neutrons, and electrons. Additionally nucl...

Isomeric states in the neutron-rich nuclei Zr111 [T1/2=0.10(7)μs], Nb113 [T1/2=0.7(4)μs], Mo115 [T1/2=46(3)μs] were first identified at the Radioactive Ion Beam Factory (RIBF) of RIKEN by using in-flight fission and fragmentation of a U238 beam at an energy of 345 MeV/u. This is a brief report of the γ transitions de-exciting from isomeric states a...

Potassium-40 is a widespread, naturally-occurring isotope whose radioactivity impacts subatomic rare-event searches, nuclear structure theory, and estimated geological ages. A predicted electron-capture decay directly to the ground state of argon-40 has never been observed. The KDK (potassium decay) collaboration reports the first, successful obser...

Potassium-40 is a naturally-occurring isotope whose radioactivity impacts estimated geological ages spanning billions of years, nuclear structure theory, and subatomic rare-event searches -- including those for dark matter and neutrinoless double-beta decay. The decays of this long-lived isotope must be precisely known for its use as a geochronomet...

The β-delayed one- and two-neutron emission probabilities (P1n and P2n) of 20 neutron-rich nuclei with N≥82 have been measured at the RIBF facility of the RIKEN Nishina Center. P1n of Ag130,131, Cd133,134, In135,136, and Sn138,139 were determined for the first time, and stringent upper limits were placed on P2n for nearly all cases. β-delayed two-n...

The β decay of Cu76 to the levels of Zn76 was studied at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Lab (ORNL). A purified Cu76 beam was developed and data were recorded for the decay of the A=76 decay chain using four high-purity germanium (HPGe) clover detectors at the Low-energy Radioactive Ion Beam Spectroscopy St...

The design and performance of a new Compton-suppressed HPGe and charged-particle array, CLARION2-TRINITY, are described. The TRINITY charged-particle array is comprised of 64 Cerium-doped Gadolinium Aluminium Gallium Garnet (GAGG:Ce) crystals configured into five rings spanning 7-54 degrees, and two annular silicon detectors that can shadow or exte...

The design and performance of a new Compton-suppressed HPGe and charged-particle array, CLARION2-TRINITY, are described. The TRINITY charged-particle array is comprised of 64 Cerium-doped Gadolinium Aluminium Gallium Garnet (GAGG:Ce) crystals configured into five rings spanning 7–54 degrees, and two annular silicon detectors that can shadow or exte...

Background: An assessment done under the auspices of the Organization for Economic Co-operation and Developement Nuclear Energy Agency (OECD-NEA) in 2007 suggested that the β decays of many abundantly produced fission products in nuclear reactors may be incomplete. In this assessment, the fission product Nb98 was assigned the highest priority for s...

Precise determination of ground-state feeding in the β decay of fission products is an important but challenging component in modeling reactor antineutrino flux and reactor decay heat. The Modular Total Absorption Spectrometer (MTAS) is a versatile NaI(Tl) detector array that determines the true β-decay pattern free from the pandemonium effect, inc...

The structure of nuclei around the neutron-rich nucleus Sn132 is of particular interest due to the vicinity of the Z=50 and N=82 shell closures and the r-process nucleosynthetic path. Four states in Sn131 with a strong single-particle-like component have previously been studied via the (d,p) reaction, with limited excitation energy resolution. The...

The structure of nuclei around the neutron-rich nucleus 132Sn is of particular interest due to the vicinity of the Z = 50 and N = 82 shell closures and the r-process nucleosynthetic path. Four states in 131Sn with a strong single-particle-like component have previously been studied via the (d,p) reaction, with limited excitation energy resolution....

The β decay of Ag125m,125 into levels in Cd125 was investigated at the Holifield Radioactive Ion Beam Facility (HRIBF). Uranium-238 targets were bombarded with 50-MeV protons with an intensity of 15μA, and the induced fission products were mass separated and deposited on a moving tape in the center of the VANDLE array consisting of γ detectors and...

Potassium-40 (⁴⁰K) is a long-lived, naturally occurring radioactive isotope. The decay products are prominent backgrounds for many rare event searches, including those involving NaI-based scintillators. ⁴⁰K also plays a role in geochronological dating techniques. The branching ratio of the electron capture directly to the ground state of ⁴⁰Ar has n...

Theoretical models of β-delayed neutron emission are used as crucial inputs in r-process calculations. Benchmarking the predictions of these models is a challenge due to a lack of currently available experimental data. In this work the β-delayed neutron emission probabilities of 33 nuclides in the important mass regions south and south-west of ¹³²S...

Neutron-rich nuclei Eu162,164 were produced by bombarding a proton beam on a U238 target at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory and mass separating the Eu162,164 products. New level schemes and new γ-ray transitions of the daughters Gd162,164 were identified from β-decay spectroscopy studies. Half-lives of t...

Potassium-40 ($^{40}$K) is a long-lived, naturally occurring radioactive isotope. The decay products are prominent backgrounds for many rare event searches, including those involving NaI-based scintillators. $^{40}$K also plays a role in geochronological dating techniques. The branching ratio of the electron capture directly to the ground state of...

Transitions in Tb163 following β decay of Gd163 were obtained as part of investigations of γ rays emitted following Eu163β decay to Gd163. Detailed analysis of the low-energy structure of Tb163 has been carried out with these data to expand previous β-decay studies and reactions studies of levels in Tb163. Data were collected at the LeRIBSS station...

Background: Neutron-rich nuclei in the mass region around A=160 have been and will continue to be of interest for the study of nuclear structure because of the rapid onset of deformation between 88 and 90 neutrons. The observation of detailed changes in nuclear structures within this mass region has provided and will continue to provide insight int...

The excitation functions for quasielastic scattering of Ne22+Cm248, Mg26+Cm248, and Ca48+U238 are measured using a gas-filled recoil ion separator. The quasielastic barrier distributions are extracted for these systems and are compared with coupled-channel calculations. The results indicate that the barrier distribution is affected dominantly by de...

Radioactive Sb129, which can be treated as a proton plus semimagic Sn128 core within the particle-core coupling scheme, was studied by Coulomb excitation. Reduced electric quadrupole transition probabilities, B(E2), for the 2+⊗πg7/2 multiplet members and candidate πd5/2 state were measured. The results indicate that the total electric quadrupole st...

Radioactive $^{129}$Sb, which can be treated as a proton plus semi-magic $^{128}$Sn core within the particle-core coupling scheme, was studied by Coulomb excitation. Reduced electric quadrupole transition probabilities, $B(E2)$, for the $2^+$ $\times$ $\pi g_{{7/2}}$ multiplet members and candidate $\pi d_{{5/2}}$ state were measured. The results i...

The population of evaporation residue entry states in the decay of the compound nucleus 160Er*(54 MeV) is investigated in a cross-bombardment employing the reactions 160 + 144Nd and 64Ni + 96Zr. Evaporation residue cross sections and entry state 7-ray fold distributions of the dominant exit channels were obtained for each reaction, using a 4π 7-ray...

β-delayed one-neutron and two-neutron branching ratios (P1n and P2n) have been measured in the decay of A=84 to 87 Ga isotopes at the Radioactive-Isotope Beam Factory (RIBF) at the RIKEN Nishina Center using a high-efficiency array of He3 neutron counters (BRIKEN). Two-neutron emission was observed in the decay of Ga84,85,87 for the first time and...

A newly developed segmented YSO scintillator detector was implemented for the first time at the RI-beam Factory at RIKEN Nishina Center as an implantation-decay counter. The results from the experiment demonstrate that the detector is a viable alternative to conventional silicon-strip detectors with its good timing resolution and high detection eff...

The astrophysical S factor for the radiative proton capture reaction on 7 Be (S 17) at low energies is affected by the s-wave scattering lengths. We report the measurement of elastic and inelastic scattering cross sections for the 7 Be + p system in the center-of-mass energy range 0.474-2.740 MeV and center-of-mass angular range 70 •-150 •. A radio...

A newly developed segmented YSO scintillator detector was implemented for the first time at RI-beam Factory at RIKEN Nishina Center as an implantation-decay counter. The experiment demonstrates that this detector is a viable alternative to conventional silicon-strip detectors with its good timing resolution and high detection efficiency for ${\rm \...

The astrophysical $S$-factor for the radiative proton capture reaction on $^7$Be ($S_{17}$) at low energies is affected by the $s$-wave scattering lengths. We report the measurement of elastic and inelastic scattering cross sections for the $^7$Be+$p$ system in the center of mass energy range of 0.474 - 2.740 MeV and center of mass angular range of...

A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and γ-ray detectors. We describe here the setup, the commissio...

As a part of a general program to evaluate production routes for Th229, we studied production of Th229 via proton-induced reactions on Th232 targets bombarded with low-energy protons, Ep≤40MeV. The reported excitation functions include those for proton-induced reactions on natural thorium yielding to Pa228,229,230&232 isotopes; Th232(p,xn) reaction...

The β decay of neutron-rich Cu74 has been studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. By using a high-resolution mass separator a purified Cu74 beam was obtained, thus allowing decay through its isobar chain to stable Ge74 without any decay chain member dominating. A total of 170γ rays were associated wi...

A new detection system has been installed at the RIKEN Nishina Center (Japan) to investigate decay properties of very neutron-rich nuclei. The setup consists of three main parts: a moderated neutron counter, a detection system sensitive to the implantation and decay of radioactive ions, and gamma-ray detectors. We describe here the setup, the commi...

Decay of Ga85 was studied by means of β-neutron-γ spectroscopy. A pure beam of Ga85 was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and a high-resolution electromagnetic separator. The β-delayed neutron emission probability was measured for the first time, yielding 70(5)%. An upper limit of...

Potassium-40 (${}^{40}$K) is a background in many rare-event searches and may well play a role in interpreting results from the DAMA dark-matter search. The electron-capture decay of ${}^{40}$K to the ground state of ${}^{40}$Ar has never been measured and contributes an unknown amount of background. The KDK (potassium decay) collaboration will mea...

Potassium-40 (${}^{40}$K) is a background in many rare-event searches and may well play a role in interpreting results from the DAMA dark-matter search. The electron-capture decay of ${}^{40}$K to the ground state of ${}^{40}$Ar has never been measured and contributes an unknown amount of background. The KDK (potassium decay) collaboration will mea...

We report the results of a β-decay study of fission products Br86, Kr89, Rb89, Rb90gs, Rb90m, Kr90, Rb92, Xe139, and Cs142 performed with the Modular Total Absorption Spectrometer (MTAS) and on-line mass-separated ion beams. These radioactivities were assessed by the Nuclear Energy Agency as having high priority for decay heat analysis during a nuc...

Beams of short-lived radioactive nuclei are needed for frontier experimental research in nuclear structure, reactions, and astrophysics. Negatively charged radioactive ion beams have unique advantages such that they allow the use of a tandem accelerator for post-acceleration, which can provide the highest beam quality and continuously variable ener...

Background: An assessment done under the auspices of the Nuclear Energy Agency in 2007 suggested that the β decays of abundant fission products in nuclear reactors may be incomplete. Many of the nuclei are potentially affected by the so called pandemonium effect and their β−γ decay heat should be restudied using the total absorption technique. The...

The β-decay properties of the very neutron-rich nucleus Ge85, produced in the proton-induced fission of U238, were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The level scheme of As523385 populated in Ge85βγ decay was reconstructed and compared to shell-model calculations. The investigation of the system...

Radioactive 136Te has two valence protons and two valence neutrons outside of the 132Sn double shell closure, providing a simple laboratory for exploring the emergence of collectivity and nucleon-nucleon interactions. Coulomb excitation of 136Te on a titanium target was utilized to determine an extensive set of electromagnetic moments for the three...

The commissioning of a new setup for β-delayed neutron measurements was carried out successfully in November-2016, at the RIKEN Nishina Center in Japan. The β-decay half-lives and Pn branching ratios of several isotopes in the 78Ni region were measured. Details of the experimental setup and the first results are given.

Actinium-225 and ²¹³Bi have been used successfully in targeted alpha therapy (TAT) in preclinical and clinical research. This paper is a continuation of research activities aiming to expand the availability of ²²⁵Ac. The high-energy proton spallation reaction on natural thorium metal targets has been utilized to produce millicurie quantities of ²²⁵...

Electroplated depositions of Sm were prepared using a vertical well-type electrodeposition unit with an aqueous ammonium acetate electrolyte system, with an average deposition yield just over 87%. The depositions were analyzed for morphology and thickness by scanning electron microscopy (SEM) and chemical composition by energy dispersion X-ray spec...

The β-delayed neutron emission of Ga83,84 isotopes was studied using the neutron time-of-flight technique. The measured neutron energy spectra showed emission from states at excitation energies high above the neutron separation energy and previously not observed in the β decay of midmass nuclei. The large decay strength deduced from the observed in...

We report total absorption spectroscopy measurements of Rb92, Y96gs, and Cs142 β decays, which are the most important contributors to the high energy ν¯e spectral shape in nuclear reactors. These three β decays contribute 43% of the ν¯e flux near 5.5 MeV emitted by nuclear reactors. This ν¯e energy is particularly interesting due to spectral featur...

The β decay of Cd124 into levels in In124 was reinvestigated at the Holifield Radioactive Ion Beam Facility. Fifty-MeV protons were bombarded on uranium targets and the induced fission products were mass separated and deposited on a moving tape in the center of an array of γ detectors. The resulting γ−γ coincidences revealed appreciable disagreemen...

β decay of neutron-rich nuclide Kr94 was reinvestigated by means of a high resolution on-line mass separator and β−γ spectroscopy. In total 22 γ-ray transitions were assigned to the decay of Kr94, and a new isomeric state was identified. The new information allows us to build detailed levels systematics in a chain of odd-odd rubidium isotopes and d...

The β-decay properties of the very neutron-rich Ge84 nucleus were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Several new γ-transitions and levels were added to its decay scheme and the order of the two lowest-lying levels in the daughter As84 was corrected. For the first time γ radiation following β-del...

DOI:https://doi.org/10.1103/PhysRevC.93.059903

Decays of neutron-rich nuclei Zn82,83 and Ga82,83 produced in proton-induced fission of U238 were studied at the Holifield Radioactive Ion Beam Facility using on-line mass separation and β-γ spectroscopy techniques. New γ-ray transitions were identified and level schemes, which include states at high excitation energies in the range between 3-7 MeV...

Multi-step resonance laser ionization has become an essential tool for the production of isobarically pure radioactive ion beams at the isotope separator on-line (ISOL) facilities around the world. A resonant ionization laser ion source (RILIS) has been developed for the former Holifield Radioactive Ion Beam Facility (HRIBF) of Oak Ridge National L...

The β-decay properties of neutron-rich As87 produced in the proton-induced fission of U238 were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The low-energy excited states in N=53 Se87 and N=52 Se86 were identified through β-γ and β-delayed neutron-γ decay of As87, respectively. The experimental systematic...

The β-decay properties of very neutron rich nuclei Ge86 and As86 were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Spectroscopic information on new excited states in As86 and in Se86 was obtained and is interpreted within an advanced shell model approach. These calculations, previously explaining well th...

We present results and discuss the use of aluminum nitride as a promising source material for Accelerator Mass Spectrometry (AMS) and Radioactive Ion Beams (RIBs) science applications of 26Al isotopes. The measurement of 26Al in geological samples by AMS is typically conducted on Al2O3 targets. However, Al2O3 is not an ideal source material because...

The Galactic 1.809-MeV γ-ray signature from the β decay of ^{26g}Al is a dominant target of γ-ray astronomy, of which a significant component is understood to originate from massive stars. The ^{26g}Al(p,γ)^{27}Si reaction is a major destruction pathway for ^{26g}Al at stellar temperatures, but the reaction rate is poorly constrained due to uncerta...

The Galactic 1.809-MeV γ-ray signature from the β decay of Al26g is a dominant target of γ-ray astronomy, of which a significant component is understood to originate from massive stars. The Al26g(p,γ)Si27 reaction is a major destruction pathway for Al26g at stellar temperatures, but the reaction rate is poorly constrained due to uncertainties in th...

Efficient ion sources are needed for detecting ultratrace U and Th impurities in a copper matrix by mass spectrometry techniques such as accelerator mass spectrometry (AMS). Two positive ion sources, a hot-cavity surface ionization source and a resonant ionization laser ion source, are evaluated in terms of ionization efficiencies for generating io...

In an experiment at the HRIBF, Oak Ridge National Laboratory, USA, we have investigated excited states in 86Se populated in the beta-decay of 86As. Several new transitions were identified. Preliminary results are presented.

The tin chain of isotopes provides a unique region in which to investigate the evolution of single-particle structure, spreading from N = 50 at 100Sn, through 10 stable isotopes and the N = 82 shell closure at 132Sn out into the r-process path. Direct reactions performed on radioactive ion beams are sensitive spectroscopic tools for studying exotic...

The lowest lying levels in the neutron-rich even-even Cd isotopes have structures that resemble an anharmonic vibrator coupled to 2-proton intruder states. Deviations from this picture have been shown to occur in ^112-120Cd isotopes [1,2]. To determine the systematics of these states across the neutron shell we have begun to measure the beta decays...

The excited states of odd-odd 82As are studied in the beta decay of 82Ge. An isotopically pure beam of 83Ga was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and high-resolution electromagnetic separation. The atoms of 82Ge are created after beta-delayed neutron emission in the decay of 83Ga....

The β-decay of the N=51 nucleus 81Zn was studied by means of β - γ spectroscopy and from isotopically pure beams produced at the HRIBF. We observe several competing β transitions populating 81Ga which are interpreted as allowed Gamow-Teller decays to positive parity, core excited states and first-forbidden decays to negative parity states. The meas...

The β decay properties of 75Cu [t1/2 = 1.222(8) s] and 77Cu [t1/2 = 480(9)ms] were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Presented is a short overview of obtained results.

γ-ray transitions in 134Te, 135Te, and 136Te were measured from 9Be-induced reactions with a radioactive 132Sn beam at a sub-Coulomb barrier energy of 3 MeV per nucleon using particle-γ coincidence spectroscopy. The transitions were selected by gating on alpha-like particles in a CsI detector following a combination of (9Be,1n), (9Be,2n), and (9Be,...

A Modular Total Absorption Spectrometer constructed at the Holifield Radioactive Ion Beam Facility has been applied to decay studies of over 20 238U fission products. The measurements were focused on nuclei identified as important for decay heat analysis during a nuclear fuel cycle. Preliminary results on the average electromagnetic (EM) energy rel...

The 253.3–keV excited state located in 93Rb was studied at the Holifield Radioactive Ion Beam Facility in Oak Ridge. This state, described as isomeric in databases, was populated in the decay of 93Kr produced by proton–induced fission of 238U and isolated using the isotope separation on–line technique. We report that the 253.3–keV level does not re...

Single-neutron states in ^{133}Sn and ^{209}Pb, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the (^{9}Be, ^{8}Be) one-neutron transfer reaction in inverse kinematics using particle-γ coincidence spectroscopy. In addition, the s_{1/2} single-neutron hole-state candidate in ^{131}Sn...

The β decay of Ag124,126 low- and high-spin isomers into levels in Cd124,126 was investigated. We have greatly expanded the decay schemes in these nuclei including the identification of the 02+ and 03+ states among 63 new levels in Cd124 and the identification of the 22+ state among 30 new levels in Cd126. Several states were identified in Cd124, w...

Single-neutron states in Sn-133 and Pb-209, which are analogous to single-electron states outside of closed atomic shells in alkali metals, were populated by the (Be-9, Be-8) one-neutron transfer reaction in inverse kinematics using particle-gamma coincidence spectroscopy. In addition, the s(1/2) single-neutron hole-state candidate in Sn-131 was po...

Spectroscopic information on nuclei in the vicinity of the doubly-magic 132Sn82 [1] is of central importance to nuclear structure as well as nuclear astrophysics. In recent nucleosynthesis calculations [2], direct neutron captures (DC) on the r-process nucleus 130Sn were shown to influence the overall production of heavy elements, with significant...

The extraction of detailed nuclear structure information from transfer reactions requires reliable, well-normalized data, as well as optical potentials and a theoretical framework demonstrated to work well in the relevant mass and beam energy ranges. It is rare that the theoretical ingredients can be tested well for exotic nuclei owing to the pauci...

The β-decays of neutron-rich nuclei near the doubly magic 78Ni were studied at the Holifield Radioactive Ion Beam Facility (HRIBF) using an electromagnetic isobar separator. The half-lives of 82Zn (228±10 ms), 83Zn (117±20 ms) and 85Ga (93±7 ms) were determined for the first time. These half-lives were found to be very different from the prediction...

The g factor and B(E2) of the first excited 2^{+} state have been measured following Coulomb excitation of the neutron-rich semimagic nuclide ^{134}Te (two protons outside ^{132}Sn) produced as a radioactive beam. The precision achieved matches related g-factor measurements on stable beams and distinguishes between alternative models. The B(E2) mea...

The extraction of detailed nuclear structure information from transfer reactions requires reliable, well-normalized data as well as optical potentials and a theoretical framework demonstrated to work well in the relevant mass and beam energy ranges. It is rare that the theoretical ingredients can be tested well for exotic nuclei owing to the paucit...

The β-decay properties of neutron-rich ^{85}Ga produced in proton-induced fission of ^{238}U were studied at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. Data consisted of β−γ and β−γ−γ coincidences were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station after high-resolution on-line mass separati...

Beta decay of ^{86}Ga was studied by means of β-neutron-γ spectroscopy. An isotopically pure ^{86}Ga beam was produced at the Holifield Radioactive Ion Beam Facility using a resonance ionization laser ion source and high-resolution electromagnetic separation. The decay of ^{86}Ga revealed a half-life of 43_{-15}^{+21} ms and large β-delayed one-neu...

Short-lived neutron-rich nuclei including 93Br, 93Kr, and 94Kr were produced in proton-induced fission of 238U at the Holifield Radioactive Ion Beam Facility in Oak Ridge. Their β decay was studied by means of a high-resolution online mass separator and β–γ spectroscopy methods. The half-life of T1/2 = 152(8) ms and β-delayed branching ratio of Pn...

The SPES (Selective Production of Exotic Species) project, under development at the Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro (INFN-LNL), is a new-generation Isotope Separation On-Line (ISOL) facility for the production of radioactive ion beams by means of the proton-induced fission of uranium. In the framework of the...

The β-decay properties of several neutron-rich germanium and arsenic isotopes were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The measurements of almost-pure radioactive sources were enabled by the combination of ion-source chemistry and two-stage mass separation. The half-life of 86 Ge (226 ± 21 ms) w...

The β-decay properties of several neutron-rich germanium and arsenic isotopes were measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The measurements of almost-pure radioactive sources were enabled by the combination of ion-source chemistry and two-stage mass separation. The half-life of 86 Ge (226 ± 21 ms) w...

The very low wear rates achieved with the current highly cross-linked ultrahigh molecular weight polyethylenes (UHMWPE) used in joint prostheses have proven to be difficult to measure accurately by gravimetry. Tracer methods are therefore being explored. The purpose of this study was to perform a proof-of-concept experiment on the use of the radioa...

A highly selective resonant ionization laser ion source has been successfully commissioned at the Holifield Radioactive Ion Beam Facility, Oak Ridge National Laboratory, for the production of pure beams of short-lived nuclei for spectroscopic studies. The laser ion source provided beams of neutron-rich Ga isotopes to the Low-energy Radioactive Ion...

We have reinvestigated the β decay of 120Ag to levels in 120Cd. Significant deviations in the decays of low-lying states from that expected from a U(5) nucleus have been observed. The results from this paper which include the 02+ and 31+ states (which have now been correctly identified) and previous work on lighter Cd isotopes strongly suggest that...

The {beta} decays of neutron-rich nuclei near the doubly magic {sup 78}Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of {sup 82}Zn (228 {+-} 10 ms), {sup 83}Zn (117 {+-} 20 ms), and {sup 85}Ga (93 {+-} 7 ms) were determined for the first time. These half-lives were found to...