28 research outputs found
Nuclear Level Density and -ray Strength Function of
The nuclear level density (NLD) and -ray strength function
(SF) of have been investigated using the Oslo
method. The extracted NLD is compared with previous measurements using particle
evaporation and those found from neutron resonance spacing. The SF was
found to feature a strong low energy enhancement that could be explained as M1
strength based on large scale shell model calculations. Comparison of
SFs measured with the Oslo method for various isotopes
reveals systematic changes to the strength below MeV with increasing mass.Comment: Submitted to Phys. Rev.
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Search for Oscillation of the Electron-Capture Decay Probability of Pm-142
We have searched for time modulation of the electron capture decay probability of 142Pm in an attempt to confirm a recent claim from a group at the Gesellschaft fur Schwerionenforschung (GSI). We produced 142Pm via the 124Sn(23Na, 5n)142Pm reaction at the Berkeley 88-Inch Cyclotron with a bombardment time short compared to the reported modulation period. Isotope selection by the Berkeley Gas-filled Separator is followed by implantation and a long period of monitoring the 142Nd K alpha x-rays from the daughter. The decay time spectrum of the x-rays is well-described by a simple exponential and the measured half-life of 40.68(53) seconds is consistent with the accepted value. We observed no oscillatory modulation at the proposed frequency at a level 31 times smaller than that reported by Litvinov (Phys. Lett. B 664 (2008) 162). A literature search for previous experiments that might have been sensitive to the reported modulation uncovered another example in 142Eu electron-capture decay. A reanalysis of the published data shows no oscillatory behavior
La(, ) cross sections constrained with statistical decay properties of La nuclei
The nuclear level densities and -ray strength functions of
La were measured using the La(He, ),
La(He, He) and La(d, p) reactions. The
particle- coincidences were recorded with the silicon particle
telescope (SiRi) and NaI(Tl) (CACTUS) arrays. In the context of these
experimental results, the low-energy enhancement in the A140 region is
discussed. The La( cross sections were calculated
at - and -process temperatures using the experimentally measured nuclear
level densities and -ray strength functions. Good agreement is found
between La( calculated cross sections and previous
measurements
Competing particle–hole excitations in ³⁰Na: Constraining state-of-the-art effective interactions
The odd–odd nucleus ³⁰Na is studied via a one-proton, one-proton–one-neutron and one-neutron removal reaction using an intermediate-energy ³¹Mg, ³²Mg and ³¹Na radioactive ion beam, respectively. Combining high-resolution γ-ray spectroscopy with the selectivity of the three reaction mechanisms, we are able to distinguish multiple particle–hole configurations. Negative-parity states in ³⁰Na are observed for the first time, providing an important measure of the excitation of the 1p1h/3p3h configuration and hence the sd–pf shell gap. The extracted band structures and level energies serve as invaluable input for the theoretical refinement of the effective interactions used in this region
Updated Photonuclear Data Library and Database for Photon Strength Functions
Photonuclear cross sections and gamma-ray data used to extract Photon Strength Functions are important for a large range of applications including basic sciences. The recommendations of an IAEA Consultant’s Meeting to update the IAEA Photonuclear Data Library and create a Reference Database for Photon Strength Functions are presented
Updated Photonuclear Data Library and Database for Photon Strength Functions
Photonuclear cross sections and gamma-ray data used to extract Photon Strength Functions are important for a large range of applications including basic sciences. The recommendations of an IAEA Consultant’s Meeting to update the IAEA Photonuclear Data Library and create a Reference Database for Photon Strength Functions are presented
Independent normalization for gamma-ray strength functions: The shape method
The shape method, a novel approach to obtain the functional form of the γ-ray strength function (γSF), is introduced. In connection with the Oslo method the slope of the nuclear level density (NLD) and γSF can be obtained simultaneously even in the absence of neutron resonance spacing data. The foundation of the shape method lies in the primary γ-ray transitions which preserve information on the functional form of the γSF. The shape method has been applied to 56Fe, 92Zr, and 164Dy, which are representative cases for the variety of situations encountered in typical NLD and γSF studies. The comparisons of results from the shape method to those from the Oslo method demonstrate that the functional form of the γSF is retained regardless of nuclear structure details or Jπ values of the states fed by the primary transitions
Encapsulated Sulfur targets for light ion beam experiments
A new method was developed to produce enriched Sulfur targets with minimum loss of material. This was made possible by inserting Sulfur in-between two 0.5 μm Mylar foils (C10H8O4). The initial aim was to ensure that the Sulfur targets reduce by no more than 50% of the initial thickness within 24 hours under the equivalent of 10 J/cm2 of integrated energy deposition by an energetic (Eb > 50 MeV) proton beam. There is no loss of enriched material while making the target, as all the material is deposited within the surface area to be exposed to the beam. During beam irradiation, the targets were frequently swivelled in order to expose each part of the target to the beam and achieve homogeneous irradiation. Targets of 0.4 mg/cm2 thickness were produced and characterised using ion beam analysis technique with a 3 MeV proton beam
Encapsulated Sulfur targets for light ion beam experiments
International audienceA new method was developed to produce enriched Sulfur targets with minimum loss of material. This was made possible by inserting Sulfur in-between two 0.5 μm Mylar foils (C10H8O4). The initial aim was to ensure that the Sulfur targets reduce by no more than 50% of the initial thickness within 24 hours under the equivalent of 10 J/cm2 of integrated energy deposition by an energetic (Eb > 50 MeV) proton beam. There is no loss of enriched material while making the target, as all the material is deposited within the surface area to be exposed to the beam. During beam irradiation, the targets were frequently swivelled in order to expose each part of the target to the beam and achieve homogeneous irradiation. Targets of 0.4 mg/cm2 thickness were produced and characterised using ion beam analysis technique with a 3 MeV proton beam
Encapsulated Sulfur targets for light ion beam experiments
A new method was developed to produce enriched Sulfur targets with minimum loss of material. This was made possible by inserting Sulfur in-between two 0.5 μm Mylar foils (C10H8O4). The initial aim was to ensure that the Sulfur targets reduce by no more than 50% of the initial thickness within 24 hours under the equivalent of 10 J/cm2 of integrated energy deposition by an energetic (Eb > 50 MeV) proton beam. There is no loss of enriched material while making the target, as all the material is deposited within the surface area to be exposed to the beam. During beam irradiation, the targets were frequently swivelled in order to expose each part of the target to the beam and achieve homogeneous irradiation. Targets of 0.4 mg/cm2 thickness were produced and characterised using ion beam analysis technique with a 3 MeV proton beam