Measurement and analysis of the 241^{241}Am(n,γ\gamma) cross section at the CERN n_TOF facility.

In the context of the current nuclear technology, the radiotoxicity of the spent fuel of a typical PWR reactor is dominated by minor actinides for times greater than 104 years. In particular, 241Am and its 432 years half-life is responsible for about half of the minor actinide content of a PWR spent fuel. This thesis work consisted in measuring and analysing the 241Am(n, ) cross section at the CERN n TOF facility. After selecting exclusively the events obtained with lead shielding in front of the C6D6 detectors, the amplitude-energy calibration has to be adjusted with time, by using a photon coming from the 27Al(,,p)30Si reaction. Histogram extraction included applying a weighting function (obtained by MCNP simulation), a dead time correction, and a normalization to the compound nucleus excitation energy. The background corrected spectra were normalized relatively to the 4.9 eV resonance on 197Au. Finally, the resonance analysis was performed using the SAMMY code. The extracted thermal value is 678±68 barns, the uncertainty being mostly due to the large background level. The resolved range was extended from 150 eV to 320 eV, with a total of 192 resonances that had to be added of heavily modified. The unresolved region was analysed up to 150 keV, yielding a larger average cross section than previously evaluated below 20 keV. 12

Feed Assessment Tool (FEAST) data repository - PHP code and database structure for website version 2.0.0

This repository hosts version 2.0.0 of the PHP code and database structure for the FEAST Global Data Repository. Improvements in this version include a refreshed homepage, spatial data entry and download, new administrator functions, allowing data revisions while leaving raw data untouched, and modernizing the codebase for PHP 7.2

Particle physics experiments 1982

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Spin Measurements of n+87Sr for Level Density Studies

We have used the 4p BaF2 gamma-ray detector array at the n TOF neutron time-of-flight facility at CERN for an experiment in order to determine the spins of resonances of n+87Sr by measuring the gamma-ray spectra and multiplicity distributions. The first results are presented here. We have assigned the orbital momentum to all evaluated resonances on the basis of their neutron widths. Further we have assigned the spin J to 16 s-wave resonances on based the population of low-lying levels.Postprint (published version

Measurement and analysis of the Am 241 (n, gamma) cross section with liquid scintillator detectors using time-of-flight spectroscopy at the n-TOF facility at CERN

The Am241(n,¿) cross section has been measured at the n-TOF facility at CERN using deuterated benzene liquid scintillators, commonly known as C6D6 detectors, and time-of-flight spectrometry. The results in the resolved resonance range bring new constraints to evaluations below 150 eV, and the energy upper limit was extended from 150 to 320 eV with a total of 172 new resonances not present in current evaluations. The thermal capture cross section was found to be sth=678±68 b, which is in good agreement with evaluations and most previous measurements. The capture cross section in the unresolved resonance region was extracted in the remaining energy range up to 150 keV, and found to be larger than current evaluations and previous measurements. © 2014 American Physical Society

Spin Measurements of n+87Sr for Level Density Studies

We have used the 4p BaF2 gamma-ray detector array at the n TOF neutron time-of-flight facility at CERN for an experiment in order to determine the spins of resonances of n+87Sr by measuring the gamma-ray spectra and multiplicity distributions. The first results are presented here. We have assigned the orbital momentum to all evaluated resonances on the basis of their neutron widths. Further we have assigned the spin J to 16 s-wave resonances on based the population of low-lying levels

Neutron cross-sections for advanced nuclear systems: the n_TOF project at CERN

The study of neutron-induced reactions is of high relevance in a wide variety of fields, ranging from stellar nucleosynthesis and fundamental nuclear physics to applications of nuclear technology. In nuclear energy, high accuracy neutron data are needed for the development of Generation IV fast reactors and accelerator driven systems, these last aimed specifically at nuclear waste incineration, as well as for research on innovative fuel cycles. In this context, a high luminosity Neutron Time Of Flight facility, n_TOF, is operating at CERN since more than a decade, with the aim of providing new, high accuracy and high resolution neutron cross-sections. Thanks to the features of the neutron beam, a rich experimental program relevant to nuclear technology has been carried out so far. The program will be further expanded in the near future, thanks in particular to a new high-flux experimental area, now under construction

Measurements of neutron cross sections for advanced nuclear energy systems at n_TOF (CERN)

The n_TOF facility operates at CERN with the aim of addressing the request of high accuracy nuclear data for advanced nuclear energy systems as well as for nuclear astrophysics. Thanks to the features of the neutron beam, important results have been obtained on neutron induced fission and capture cross sections of U, Pu and minor actinides. Recently the construction of another beam line has started; the new line will be complementary to the first one, allowing to further extend the experimental program foreseen for next measurement campaigns

238U(n, γ) reaction cross section measurement with C6D6 detectors at the n_TOF CERN facility

The radiative capture cross section of 238U is very important for the developing of new reactor technologies and the safety of existing ones. Here the preliminary results of the 238U(n,γ) cross section measurement performed at n_TOF with C6D6 scintillation detectors are presented, paying particular attention to data reduction and background subtraction

Experimental neutron capture data of 58Ni from the CERN n_TOF facility

The neutron capture cross section of 58Ni was measured at the neutron time of flight facility n_TOF at CERN, from 27 meV to 400 keV neutron energy. Special care has been taken to identify all the possible sources of background, with the so-called neutron background obtained for the first time using high-precision GEANT4 simulations. The energy range up to 122 keV was treated as the resolved resonance region, where 51 resonances were identified and analyzed by a multilevel R-matrix code SAMMY. Above 122 keV the code SESH was used in analyzing the unresolved resonance region of the capture yield. Maxwellian averaged cross sections were calculated in the temperature range of kT = 5 – 100 keV, and their astrophysical implications were investigated