660 research outputs found
beta decay of In-133 : gamma emission from neutron-unbound states in Sn-133
Excited states in Sn-133 were investigated through the beta decay of In-133 at the ISOLDE facility. The ISOLDE Resonance Ionization Laser Ion Source (RILIS) provided isomer-selective ionization for In-133, allowing us to study separately, and in detail, the beta-decay branch of In-133 J(pi)= (9/2(+)) ground state and its J(pi) = (1/2(-)) isomer.Thanks to the large spin difference of the two beta-decaying states of In-133, it is possible to investigate separately the lower and higher spin states in the daughter, Sn-133, and thus to probe independently different single-particle and single-hole levels. We report here new gamma transitions observed in the decay of In-133, including those assigned to the deexcitation of the neutron-unbound states.Peer reviewe
Detailed spectroscopy of doubly magic Sn-132
The structure of the doubly magic Sn-132(50)82 has been investigated at the ISOLDE facility at CERN, populated both by the beta(-) decay of In-132 and beta(-)-delayed neutron emission of In-133. The level scheme of Sn-13(2) is greatly expanded with the addition of 68 gamma transitions and 17 levels observed for the first time in the beta decay. The information on the excited structure is completed by new gamma transitions and states populated in the beta-n decay of In-133. Improved delayed neutron emission probabilities are obtained both for In-132 and In-133. Level lifetimes are measured via the advanced time-delayed beta gamma gamma(t) fast-timing method. An interpretation of the level structure is given based on the experimental findings and the particle-hole configurations arising from core excitations both from the N = 82 and Z = 50 shells, leading to positive- and negative-parity particle-hole multiplets. The experimental information provides new data to challenge the theoretical description of Sn-132.Peer reviewe
Commissioning of the spede spectrometer with stable beams
The SPectrometer for Electron DEtection (SPEDE) has been constructed for in-beam nuclear structure studies using radioactive ion beams. SPEDE employs a silicon detector for detecting conversion electrons. It is designed to be used in conjunction with the MINIBALL spectrometer at HIE-ISOLDE, CERN.Peer reviewe
Grain - A Java Analysis Framework for Total Data Readout
Grain is a data analysis framework developed to be used with the novel Total
Data Readout data acquisition system. In Total Data Readout all the electronics
channels are read out asynchronously in singles mode and each data item is
timestamped. Event building and analysis has to be done entirely in the
software post-processing the data stream. A flexible and efficient event parser
and the accompanying software framework have been written entirely in Java. The
design and implementation of the software are discussed along with experiences
gained in running real-life experiments.Comment: Submitted to NIM
Shape coexistence at the proton drip-line: First identification of excited states in 180Pb
Excited states in the extremely neutron-deficient nucleus, 180Pb, have been
identified for the first time using the JUROGAM II array in conjunction with
the RITU recoil separator at the Accelerator Laboratory of the University of
Jyvaskyla. This study lies at the limit of what is presently achievable with
in-beam spectroscopy, with an estimated cross-section of only 10 nb for the
92Mo(90Zr,2n)180Pb reaction. A continuation of the trend observed in 182Pb and
184Pb is seen, where the prolate minimum continues to rise beyond the N=104
mid-shell with respect to the spherical ground state. Beyond mean-field
calculations are in reasonable correspondence with the trends deduced from
experiment.Comment: 5 pages, 4 figures, submitted to Phys.Rev.
Search for Fingerprints of Tetrahedral Symmetry in
Theoretical predictions suggest the presence of tetrahedral symmetry as an
explanation for the vanishing intra-band E2-transitions at the bottom of the
odd-spin negative parity band in . The present study reports on
experiment performed to address this phenomenon. It allowed to determine the
intra-band E2 transitions and branching ratios B(E2)/B(E1) of two of the
negative-parity bands in .Comment: presented by Q.T. Doan at XLII Zakopane School of Physics: Breaking
Frontiers: Submicron Structures in Physics and Biology, May 2008. 5 pages,
minor corrections. To be published in the proceeding
First observation of excited states in 173Hg
The neutron-deficient nucleus 173Hg has been studied following
fusion-evaporation reactions. The observation of gamma rays decaying from
excited states are reported for the first time and a tentative level scheme is
proposed. The proposed level scheme is discussed within the context of the
systematics of neighbouring neutron-deficient Hg nuclei. In addition to the
gamma-ray spectroscopy, the alpha decay of this nucleus has been measured
yielding superior precision to earlier measurements.Comment: 5 pages, 4 figure
Single cell mutant selection for metabolic engineering of actinomycetes
Actinomycetes are important producers of pharmaceuticals and industrial enzymes. However, wild type strains require laborious development prior to industrial usage. Here we present a generally applicable reporter-guided metabolic engineering tool based on random mutagenesis, selective pressure, and single-cell sorting. We developed fluorescence-activated cell sorting (FACS) methodology capable of reproducibly identifying highperforming individual cells from a mutant population directly from liquid cultures. Actinomycetes are an important source of catabolic enzymes, where product yields determine industrial viability. We demonstrate 5fold yield improvement with an industrial cholesterol oxidase ChoD producer Streptomyces lavendulae to 20.4 U g-1 in three rounds. Strain development is traditionally followed by production medium optimization, which is a time-consuming multi-parameter problem that may require hard to source ingredients. Ultra-high throughput screening allowed us to circumvent medium optimization and we identified high ChoD yield production strains directly from mutant libraries grown under preset culture conditions. Genome-mining based drug discovery is a promising source of bioactive compounds, which is complicated by the observation that target metabolic pathways may be silent under laboratory conditions. We demonstrate our technology for drug discovery by activating a silent mutaxanthene metabolic pathway in Amycolatopsis. We apply the method for industrial strain development and increase mutaxanthene yields 9-fold to 99 mg l- 1 in a second round of mutant selection. In summary, the ability to screen tens of millions of mutants in a single cell format offers broad applicability for metabolic engineering of actinomycetes for activation of silent metabolic pathways and to increase yields of proteins and natural products.Peer reviewe
The JUROGAM 3 spectrometer
The jurogam 3 spectrometer has been constructed for in-beam gamma-ray spectroscopy experiments in the Accelerator Laboratory of the University of Jyvaskyla, Finland. jurogam 3 consists of germanium-detector modules in a compact geometry surrounding a target to measure. rays emitted from radioactive nuclei. jurogam 3 can be employed in conjunction with one of two recoil separators, the mara vacuum-mode separator or the ritu gas-filled separator, and other ancillary devices.Peer reviewe
Quasiparticle alignments and alpha-decay fine structure of Pt-175
Excited states and decay properties of 175 Pt have been investigated using the 92 Mo ( 86 Sr , 2 p n ) fusion-evaporation reaction. The JUROGAM I γ -ray spectrometer and the GREAT spectrometer were used in conjunction with the gas-filled recoil separator RITU for the measurement of the radiation at the target and focal plane positions, respectively. Two new band structures, assigned to be based on the I π = ( 7 / 2 − ) ground state in 175 Pt, have been established and the known yrast band has been extended up to I π = ( 49 / 2 + ) . Rotational properties of the excited states in 175 Pt have been investigated within the cranked shell-model formalism. The low-frequency changes in the alignments of the positive- and negative-parity bands are interpreted as a sign of proton-pair excitations in the rotating core. Furthermore, the α -decay measurements reveal a candidate for a fourth α -decay branch in 175 Pt, feeding a non-yrast state in 171 Os
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