The fission experimental programme at the CERN n_TOF facility: status and perspectives

Colonna, N.; Tsinganis, A.; Vlastou, R.; Patronis, N.; Diakaki, Μ.; Amaducci, S.; Barbagallo, M.; Bennett, S.; Berthoumieux, E.; Bacak, M.; Coséntino, L.; Cristallo, S.; Finocchiaro, P.; Heyse, J.; Lewis, D. A.; Manna, A.; Massimi, C.; Mendoza, E.; Mirea, M.; Meynier, André; Nolte, Roeland J. M.; Pirovano, E.; Sabaté-Gilarte, M.; Sibbens, G.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tarrío, D.; Tassan‐Got, L.; Vanleeuw, D.; Ventura, A.; Vescovi, D.; Wright, T.; Žugec, P.

doi:10.1140/epja/s10050-020-00037-8

Cited by 20 publications

(14 citation statements)

References 169 publications

(271 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Some of the previous ambiguities are know from long time [88,89,90], and summarized recently in Ref. [91], but no satisfactory solutions were found. Therefore, if a such analyze is applied to a specific isotope, it provides information about some observable that are only appropriate to the investigated nucleus.…”

Section: Brief Historymentioning

confidence: 99%

Notes on Fission Dynamics

Mirea¹

2020

AnnalsARSciPhysChem

View full text Add to dashboard Cite

The dynamics of the nuclear fission is a complex phenomenon, being not yet described adequately from the theoretical point of view. At present, they are not models giving a complete description of the richness of the features which characterizes this phenomenon. It is the mean reason for which I called this paper Notes on Fission Dynamics, being certain that I will not be able to make a global description, but only a picture underlining some particularities. So, this mini-overview should be considered only a part of the collection of articles treating the nuclear physics, published as a special number in the review of the Academy of Romanian Scientists, without an exhaustive character. A theory treating the nuclear fission is by excellence based on quantum mechanics. That is, a theory concerning the interactions between the smallest pieces that constitute a many-body nucleus. But, at present it is not possible to perform ab-initio calculations to describe the many-body structure of heavy nuclei which undergo fission by starting from fundamental interactions. To make the problem tractable, the nucleus as a whole are constrained by some collective parameters, associated to some collective degree of freedom. The collective variables are forced to vary, leading to a scission of the nuclear system. The response of the nuclear system to the external forces is given by the nuclear inertia. The mean field potential between the nucleons is obtained after a proper average, and then used to solve the Schrodinger equation. The treatments presented in this article are based on these simplifying concepts. I will give some examples of calculations that include the dissipation and the configuration mixing due to radial and angular couplings. The importance of the subject is also briefly reviewed.

show abstract

Section: Brief Historymentioning

confidence: 99%

Notes on Fission Dynamics

Mirea¹

2020

AnnalsARSciPhysChem

View full text Add to dashboard Cite

show abstract

“…Exponential fits in waiting time distributions are a useful experimental tool in estimating counting losses by calculating the integral below the extrapolated fitting function[46].…”

mentioning

confidence: 99%

Investigation of the Pu240(n,f) reaction at the n_TOF/EAR2 facility in the 9 meV–6 MeV range

Stamatopoulos¹,

Tsinganis²,

Colonna³

et al. 2020

Phys. Rev. C

Self Cite

View full text Add to dashboard Cite

Background: Nuclear waste management is considered amongst the major challenges in the field of nuclear energy. A possible means of addressing this issue is waste transmutation in advanced nuclear systems, whose operation requires a fast neutron spectrum. In this regard, the accurate knowledge of neutron-induced reaction cross sections of several (minor) actinide isotopes is essential for design optimization and improvement of safety margins of such systems. One such case is 240 Pu, due to its accumulation in spent nuclear fuel of thermal reactors and its usage in fast reactor fuel. The measurement of the 240 Pu(n, f) cross section was previously attempted at the CERN n_TOF facility EAR1 measuring station using the time-of-flight technique. Due to the low amount of available material and the given flux at EAR1, the measurement had to last several months to achieve a sufficient statistical accuracy. This long duration led to detector deterioration due to the prolonged exposure to the high α activity of the fission foils, therefore the measurement could not be successfully completed. Purpose: It is aimed to determine whether it is feasible to study neutron-induced fission at n_TOF/EAR2 and provide data on the 240 Pu(n, f) reaction in energy regions requested for applications. Methods: The study of the 240 Pu(n, f) reaction was made at a new experimental area (EAR2) with a shorter flight path which delivered on average 30 times higher flux at fast neutron energies. This enabled the measurement to be performed much faster, thus limiting the exposure of the detectors to the intrinsic activity of the fission foils. The experimental setup was based on microbulk Micromegas detectors and the time-of-flight data were analyzed with an optimized pulse-shape analysis algorithm. Special attention was dedicated to the estimation of the non-negligible counting loss corrections with the development of a new methodology, and other corrections were estimated via Monte Carlo simulations of the experimental setup. Results: This new measurement of the 240 Pu(n, f) cross section yielded data from 9 meV up to 6 MeV incident neutron energy and fission resonance kernels were extracted up to 10 keV. Conclusions: Neutron-induced fission of high activity samples can be successfully studied at the n_TOF/EAR2 facility at CERN covering a wide range of neutron energies, from thermal to a few MeV.

show abstract

“…At n_TOF, a pulsed proton beam impinges on a thick lead target, creating neutrons through spallation reactions. The protons are initially accelerated in the Proton Synchrotron (PS) (Figure 4.1) to 20 GeV/c, and concentrated in short pulses with a width of 7 ns (rms) and a repetition rate of 0.8 Hz [29,30]. These pulses are delivered either at full intensity (dedicated) of 7 -8 • 10 12 protons or low intensity of 3 • 10 12 protons, remaining from not fully used proton bunches sent to other facilities (parasitic).…”

Section: Facility Overviewmentioning

confidence: 99%

“…• The width of the proton beam of 7 ns rms [29,30]. This effect cannot be compensated for, and provides a lower bound for the time resolution ∆t.…”

Section: Tof To Energy Conversionmentioning

confidence: 99%

See 1 more Smart Citation

Neutron capture on gallium in the astrophysical s process using time of flight

Kurtulgil¹

View full text Add to dashboard Cite

The stellar nucleosynthesis of elements heavier than iron can primarily be attributed to neutron capture reactions in the s and r process. While the s process is considered to be well understood with regards to the stellar sites, phases and conditions where it occurs, nucleosynthesis networks still need accurate neutron capture cross sections with low uncertainties as input parameters. Their quantitative outputs for the isotopic abundances produced in the s process, coupled with the observable solar abundances, can be used to indirectly infer the expected r process abundances. The two stable gallium isotopes, 69Ga and 71Ga, have been shown in sensitivity studies to have considerable impact on the weak s process in massive stars. The available experimental data, mostly derived from neutron activation measurements for quasi-stellar neutron spectra at kBT = 25 keV, show disagreements up to a factor of three. Determining the differential neutron capture cross section can provide input data for the whole range of astrophysically relevant energies. To that end, a neutron time of flight experimental campaign at the n_TOF facility at CERN was performed for three months, using isotopically enriched samples of both isotopes. The data taken at the EAR1 experimental area covered a wide neutron energy range from thermal to several hundred keV. The respective differential and spectrum averaged neutron capture cross sections for 69Ga and 71Ga were determined in this thesis. They show good agreement with the evaluated cross sections for 71Ga, but reproduce the deviations from the evaluated data that other, more recent activation measurements showed for 69Ga.

show abstract

The fission experimental programme at the CERN n_TOF facility: status and perspectives

Cited by 20 publications

References 169 publications

Notes on Fission Dynamics

Notes on Fission Dynamics

Investigation of the Pu240(n,f) reaction at the n_TOF/EAR2 facility in the 9 meV–6 MeV range

Neutron capture on gallium in the astrophysical s process using time of flight

Contact Info

Product

Resources

About