The Gamow-Teller strength distribution of the decay of 186Hg into 186Au has been determined for the first time using the total absorption gamma spectroscopy technique and has been compared with ...theoretical QRPA calculations using the SLy4 Skyrme force. The measured Gamow-Teller strength distribution and the half-life are described by mixing oblate and prolate configurations independently in the parent and daughter nuclei. In this theoretical framework the best description of the experimental beta strength is obtained with dominantly prolate components for both parent 186Hg and daughter 186Au. The approach also allowed us to determine an upper limit of the oblate component in the parent state. The complexity of the analysis required the development of a new approach in the analysis of the X-ray gated total absorption spectrum.
•The Gamow-Teller strength distribution of the decay of 186Hg into 186Au has been determined for the first time using the total absorption gamma spectroscopy technique and has been compared with theoretical QRPA calculations using the SLy4 Skyrme force.•The measured Gamow-Teller strength distribution and the half-life are described by mixing oblate and prolate configurations independently in the parent and daughter nuclei. In this theoretical framework the best description of the experimental beta strength is obtained with dominantly prolate components for both parent 186Hg and daughter 186Au.•The approach also allowed us to determine an upper limit of the oblate component in the parent state, which also describes nicely the experimental beta strength and provides the best description of the half-life of the decay within this framework.•The complexity of the analysis required the development of a new approach in the analysis of the X-ray gated total absorption spectrum. This approach can also be of particular interest for cases where the β+ component of the β-decay can contaminate the X-ray gated spectra.
The recently developed praseodymium-doped lutetium aluminum garnet, LuAG(Pr), holds a strong potential for fast timing applications. In this study we report on the time response of LuAG(Pr) at 22Na ...and 60Co photon energies. The measurements were performed using a small crystal cube of 1cm3 coupled to a Hamamatsu R5320 photomultiplier tube. The full width at half maximum (FWHM) time resolution is found to be 147±2ps at 60Co energies, and 238±2ps at 22Na.
We report on the first measurement of the half-lives of Kπ=11− and 12+ four-quasiparticle states in the even-even nucleus 178W. The sub-nanosecond half-lives were measured by applying the centroid ...shift method to data taken with LaBr3(Ce) scintillator detectors of the NuBall array at the ALTO facility in Orsay, France. The half-lives of these states only became experimentally accessible by the combination of several experimental techniques - scintillator fast timing, isomer spectroscopy with a pulsed beam, and the event-by-event calorimetry information provided by the NuBall array. The measured half-lives are 476(44)ps and 275(65)ps for the Iπ=11− and 12+ states, respectively. The decay transitions include weakly hindered E1 and E2 branches directly to the ground-state band, bypassing the two-quasiparticle states. This is the first such observation for an E1 transition. The interpretation of the small hindrance hinges on mixing between the ground-state band and the t-band.
Search for beta-delayed proton emission from 11Be Riisager, K.; Borge, M. J. G.; Briz, J. A. ...
The European physical journal. A, Hadrons and nuclei,
2020/3, Letnik:
56, Številka:
3
Journal Article
Recenzirano
We report on an attempt to reproduce the observation of
β
-
-delayed proton emission from
11
Be through detection of the final state nucleus
10
Be with accelerator mass spectrometry. Twelve samples ...were collected at the ISOLDE facility at CERN at different separator settings, allowing tests of different sources of contamination to be carried out. The observed amounts of
10
Be per collected
11
Be rule out several contamination sources, but do not agree internally. Formation of BeH molecular ions in the ion source may explain our data, in which case an upper limit of the
β
p branching ratio of
2.2
×
10
-
6
can be derived.
Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn=0 requirement plays a major role in the β decay of heavy ...neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z=50 (for N>82) and Z=82 (for N>126). The level of forbiddenness of the Δn=1ν1g9/2→π0g7/2 transition has been investigated from the β− decay of the ground state of 207Hg into the single-proton-hole nucleus 207Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g7/2−1 state in 207Tl, an upper limit of 3.9×10−3% was obtained for the probability of this decay, corresponding to logft>8.8 within a 95% confidence limit. This is the most stringent test of the Δn=0 selection rule to date.
The accurate determination of reactor antineutrino spectra remains a very hot research topic, where new questions have emerged in recent years. Indeed, after the “reactor anomaly” – a deficit of ...measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements with respect to the same spectral predictions. This puzzle is called the “shape anomaly”. Recently summation calculations of reactor antineutrino spectra based on the use of nuclear data have obtained the best agreement to date with the reactor neutrino flux measurements at the level of 2% thanks to a decade of Total Absorption Gamma-ray Spectroscopy (TAGS) measurements at the radioactive beam facility of the University of Jyväskylä in two experimental campaigns. A selection of the results obtained so far is presented.
CeBr3 crystals meet many of the demands of high performance scintillators, due to their excellent timing properties, good effective Z and high photon yield. It is important to characterize their ...efficiency and to verify whether modern Monte Carlo codes are reliable enough to reproduced the observed values. We report here on the measurement of both total and photopeak efficiency of a 1” diameter×1” height CeBr3 crystal for gamma-ray energies up to 1.4MeV at several distances, using a variety of low energy gamma rays sources. The measured experimental efficiencies are compared with simulations developed in the framework of PENELOPE and GEANT4.
•Measurement of photopeak efficiency of a CeBr3 scintillator coupled to a fast PMT.•Geometry implemented in the PENELOPE and GEANT4 Monte Carlo codes.•Both PENELOPE and GEANT4 reproduce the measured values.•Monte Carlo simulations are sensitive to the details of the geometry.•Simulations useful for this type of crystal with similar or modified geometries
The reaction of a pulsed 18O beam on a self-supporting and gold-backed isotopically-enriched 164Dy target of thickness 6.3 mg/cm2 at separate primary beam energies of 71, 76 and 80 MeV was studied at ...the accelerator at the ALTO facility of the IPN Orsay. The γ rays produced were detected using the newly-constructed ν-Ball spectrometer which comprised of HPGe and LaBr3(Ce) detectors. This conference paper describes the methodology and effectiveness of multiplicity/sum-energy gating, for channel selection between fusion evaporation events and lower multiplicity/energy events from inelastic nuclear scattering and Coulomb excitation of the target, and from two-neutron transfer reactions to 166Dy.
CeBr
crystals meet many of the demands of high performance scintillators, due to their excellent timing properties, good effective Z and high photon yield. It is important to characterize their ...efficiency and to verify whether modern Monte Carlo codes are reliable enough to reproduced the observed values. We report here on the measurement of both total and photopeak efficiency of a 1" diameter×1" height CeBr
crystal for gamma-ray energies up to 1.4MeV at several distances, using a variety of low energy gamma rays sources. The measured experimental efficiencies are compared with simulations developed in the framework of PENELOPE and GEANT4.
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