Substrate rocks of Fe-Mn crusts on the IOAN and Dalmorgeologiya Guyots

Substratum of cobalt-manganese crusts penetrated by numerous deep-sea drill holes on the IOAN and Dalmorgeologiya Guyots of Magellan Seamounts in the Pacific Ocean has been studied. Rocks have been characterized, and ferromanganese manifestations developed in the substratum in different forms have been studied in detail. They are considered to be products of deposition of water fluids arising in the volcanic pedestal and unloading on the guyot's periphery when penetrating into top parts of rocks to different degree phosphatized mainly by replacement. It is demonstrated by numerous substratum relicts and remains of organisms in them

The Np-237(n,f) cross section at the CERN n-TOF facility

The Np-237(n,f) cross sections have been measured at the n-TOF facility relative to the U-235 and U-238 fission cross sections. The n-TOF spallation neutron source at CERN is characterized by a high intensity flux, an excellent time resolution and an extensive neutron energy range (from eV to GeV). A fast ionization chamber was used as a fission fragment detector with efficiency better than 97%. Preliminary Np-237(n,f) cross sections have been deduced in the energy range from 20 keV to 10 MeV and are found in good agreement with data from literature

High-resolution study of ²³⁷Np fission cross section from 5 eV to 1 MeV

A series of measurements of Np-237 fission cross section have been performed at the CERN spallation neutron facility n_TOF which covers a wide energy range from 1 eV up to 250 MeV. A fast ionization chamber (FIC) was used as a fission fragment detector with registration efficiency of not less than 97 correct the fission cross section with use of U-235 standard. Total experimental uncertainties are determined to be at the level of 3 Analysis of the experimental data in the restricted neutron energy from 5 eV up to I MeV showed a systematic deviation from evaluated data (ENDF/B-VI). This discrepancy amounts to up to a factor 3 for resolved resonances in the neutron energy range of 5 eV - 2 KeV, and is in good agreement with some previous experiments. A similar disagreement at the level of 6-7 = 300 keV-1 MeV). This energy range is essential for the transmutation of neptunium in ADS or fast reactors. It is concluded that an updated evaluation of nuclear data for. Np-237 is required

Neutron-induced fission cross section of 237^{237}Np in the keV to MeV range at the CERN n_TOF facility

International audienceThe neutron-induced fission cross section of 237Np was experimentally determined at the high-resolutionand high-intensity facility n TOF, at CERN, in the energy range 100 keV to 9 MeV, using the 235U(n,f ) and 238U(n,f ) cross section standards below and above 2 MeV, respectively. A fast ionization chamber was usedin order to detect the fission fragments from the reactions and the targets were characterized as far as theirmass and homogeneity are concerned by means of α spectroscopy and Rutherford backscattering spectroscopyrespectively. Theoretical calculations within the Hauser-Feshbach formalism have been performed, employingthe EMPIRE code, and the model parameters were tuned in order to successfully reproduce the experimental fissioncross-sectional data and simultaneously all the competing reaction channels