170 research outputs found
Ion counting efficiencies at the IGISOL facility
At the IGISOL-JYFLTRAP facility, fission mass yields can be studied at high
precision. Fission fragments from a U target are passing through a Ni foil and
entering a gas filled chamber. The collected fragments are guided through a
mass separator to a Penning trap where their masses are identified. This
simulation work focuses on how different fission fragment properties (mass,
charge and energy) affect the stopping efficiency in the gas cell. In addition,
different experimental parameters are varied (e. g. U and Ni thickness and He
gas pressure) to study their impact on the stopping efficiency. The simulations
were performed using the Geant4 package and the SRIM code. The main results
suggest a small variation in the stopping efficiency as a function of mass,
charge and kinetic energy. It is predicted that heavy fragments are stopped
about 9% less efficiently than the light fragments. However it was found that
the properties of the U, Ni and the He gas influences this behavior. Hence it
could be possible to optimize the efficiency.Comment: 52 pages, 44 figure
Propagation of nuclear data uncertainties for ELECTRA burn-up calculations
The European Lead-Cooled Training Reactor (ELECTRA) has been proposed as a
training reactor for fast systems within the Swedish nuclear program. It is a
low-power fast reactor cooled by pure liquid lead. In this work, we propagate
the uncertainties in Pu-239 transport data to uncertainties in the fuel
inventory of ELECTRA during the reactor life using the Total Monte Carlo
approach (TMC). Within the TENDL project the nuclear models input parameters
were randomized within their uncertainties and 740 Pu-239 nuclear data
libraries were generated. These libraries are used as inputs to reactor codes,
in our case SERPENT, to perform uncertainty analysis of nuclear reactor
inventory during burn-up. The uncertainty in the inventory determines
uncertainties in: the long-term radio-toxicity, the decay heat, the evolution
of reactivity parameters, gas pressure and volatile fission product content. In
this work, a methodology called fast TMC is utilized, which reduces the overall
calculation time. The uncertainty in the long-term radiotoxicity, decay heat,
gas pressure and volatile fission products were found to be insignificant.
However, the uncertainty of some minor actinides were observed to be rather
large and therefore their impact on multiple recycling should be investigated
further. It was also found that, criticality benchmarks can be used to reduce
inventory uncertainties due to nuclear data. Further studies are needed to
include fission yield uncertainties, more isotopes, and a larger set of
benchmarks.Comment: 4 pages, 4 figures, Proc. 2013 International Conference on Nuclear
Data for Science & Technology (ND2013), March 4-8, 2013, New York, USA, to be
published in Nuclear Data Sheet
Light-ion production in the interaction of 96 MeV neutrons with oxygen
Double-differential cross sections for light-ion (p, d, t, He-3 and alpha)
production in oxygen, induced by 96 MeV neutrons are reported. Energy spectra
are measured at eight laboratory angles from 20 degrees to 160 degrees in steps
of 20 degrees. Procedures for data taking and data reduction are presented.
Deduced energy-differential and production cross sections are reported.
Experimental cross sections are compared to theoretical reaction model
calculations and experimental data at lower neutron energies in the literature.
The measured proton data agree reasonably well with the results of the model
calculations, whereas the agreement for the other particles is less convincing.
The measured production cross sections for protons, deuterons, tritons and
alpha particles support the trends suggested by data at lower energies.Comment: 21 pages, 13 figures, submitted to Phys. Rev.
Three-body interactions in colloidal systems
We present the first direct measurement of three-body interactions in a
colloidal system comprised of three charged colloidal particles. Two of the
particles have been confined by means of a scanned laser tweezers to a
line-shaped optical trap where they diffused due to thermal fluctuations. Upon
the approach of a third particle, attractive three-body interactions have been
observed. The results are in qualitative agreement with additionally performed
nonlinear Poissson-Boltzmann calculations, which also allow us to investigate
the microionic density distributions in the neighborhood of the interacting
colloidal particles
Nucleon-induced reactions at intermediate energies: New data at 96 MeV and theoretical status
Double-differential cross sections for light charged particle production (up
to A=4) were measured in 96 MeV neutron-induced reactions, at TSL laboratory
cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U,
were performed using two independent devices, SCANDAL and MEDLEY. The data were
recorded with low energy thresholds and for a wide angular range (20-160
degrees). The normalization procedure used to extract the cross sections is
based on the np elastic scattering reaction that we measured and for which we
present experimental results. A good control of the systematic uncertainties
affecting the results is achieved. Calculations using the exciton model are
reported. Two different theoretical approches proposed to improve its
predictive power regarding the complex particle emission are tested. The
capabilities of each approach is illustrated by comparison with the 96 MeV data
that we measured, and with other experimental results available in the
literature.Comment: 21 pages, 28 figure
Neutron-induced Light Ion Production From Fe, Pb And U At 96 Mev
Double-differential cross sections for light-ion production (up to A=4) induced by 96 MeV neutrons have been measured for Fe, Pb and U. The experiments have been performed at the The Svedberg Laboratory in Uppsala, using two independent devices, MEDLEY and SCANDAL. The recorded data cover a wide angular range (20º - 160º) with low energy thresholds. The work was performed within the HINDAS collaboration studying three of the most important nuclei for incineration of nuclear waste with accelerator-driven systems (ADS). The obtained cross section data are of particular interest for the understanding of the so-called pre-equilibrium stage in a nuclear reaction and are compared with model calculations performed with the GNASH, TALYS and PREEQ code
Light-ion production in the interaction of 175 MeV quasi-mono-energetic neutrons with iron and with bismuth
Nuclear data for neutron-induced reactions in the intermediate energy range
of 20 to 200 MeV are of great importance for the development of nuclear
reaction codes since little data exist in that range. Also several different
applications benefit from such data, notably accelerator-driven incineration of
nuclear waste. The Medley setup was used for a series of measurements of p, d,
t, He and -particle production by 175 MeV quasi-mono-energetic
neutrons on various target nuclei. The measurements were performed at the The
Svedberg Laboratory in Uppsala, Sweden. Eight detector telescopes placed at
angles between 20 and 160 were used. Medley uses the -- technique to discriminate among the particle types and is
able to measure double-differential cross sections over a wide range of
particle energies. This paper briefly describes the experimental setup,
summarizes the data analysis and reports on recent changes in the previously
reported preliminary data set on bismuth. Experimental data are compared with
INCL4.5-Abla07, MCNP6 using CEM03.03, TALYS and PHITS model calculations as
well as with nuclear data evaluations. The models agree fairly well overall but
in some cases systematic differences are found.Comment: 16 pages, 19 figures; submitted to Phys. Rev.
A Novel Fast Neutron Detector For Nuclear Data Measurements
International audienceAccelerator driven system will use a heavy element target such as lead. Many calculations are available to simulate high-energy spallation neutron induced reactions, but little data are available for comparison with the simulations. In order to constrain the simulation tools we have measured (n,Xn) double differential cross section on different targets at The Svedberg Laboratory, Uppsala, Sweden. For neutron energy above 40 MeV, we have developed a novel detector, CLODIA, based on proton recoil and drift chambers to determine neutron energy. CLODIA (Chamber for LOcalization with DrIft and Amplification) is able to track recoil protons with energy up to 90 MeV with spatial resolution of about one millimeter and a detection efficiency of 99% for each drift chamber. Using CLODIA coupled with the SCANDAL set-up, we have been able to measure double differential (n,Xn) cross section on lead and iron for incident neutron energy in the 40-95 MeV energy region
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