355 research outputs found

    An improved method for estimating the neutron background in measurements of neutron capture reactions

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    The relation between the neutron background in neutron capture measurements and the neutron sensitivity related to the experimental setup is examined. It is pointed out that a proper estimate of the neutron background may only be obtained by means of dedicated simulations taking into account the full framework of the neutron-induced reactions and their complete temporal evolution. No other presently available method seems to provide reliable results, in particular under the capture resonances. An improved neutron background estimation technique is proposed, the main improvement regarding the treatment of the neutron sensitivity, taking into account the temporal evolution of the neutron-induced reactions. The technique is complemented by an advanced data analysis procedure based on relativistic kinematics of neutron scattering. The analysis procedure allows for the calculation of the neutron background in capture measurements, without requiring the time-consuming simulations to be adapted to each particular sample. A suggestion is made on how to improve the neutron background estimates if neutron background simulations are not available.Comment: 11 pages, 9 figure

    Observation of large scissors resonance strength in actinides

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    The orbital M1-scissors resonance (SR) has been measured for the first time in the quasi-continuum of actinides. Particle-gamma coincidences are recorded with deuteron and 3He induced reactions on 232Th. The residual nuclei 231,232,233Th and 232,233Pa show an unexpectedly strong integrated strength of BM1=11−15μn2B_{M1} = 11-15 \mu_{n}^{2} in the Egamma=1.0 - 3.5 MeV region. The increased gamma-decay probability in actinides due to the SR is important for cross-section calculations for future fuel cycles of fast nuclear reactors and may also have impact on stellar nucleosynthesis.Comment: 5 pages and 4 figure

    Measurement of the 242Pu(n,f) cross section at n_TOF

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    Knowledge of neutron cross sections of various plutonium isotopes and other minor actinides is crucial for the design of advanced nuclear systems. The 242Pu(n,f) cross sections were measured at the CERN n-TOF facility, taking advantage of the wide energy range (from thermal to GeV) and the high instantaneous flux of the neutron beam. In this work, preliminary results are presented along with a theoretical cross section calculation performed with the EMPIRE code. © Owned by the authors, published by EDP Sciences, 2014

    Pulse processing routines for neutron time-of-flight data

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    A pulse shape analysis framework is described, which was developed for n_TOF-Phase3, the third phase in the operation of the n_TOF facility at CERN. The most notable feature of this new framework is the adoption of generic pulse shape analysis routines, characterized by a minimal number of explicit assumptions about the nature of pulses. The aim of these routines is to be applicable to a wide variety of detectors, thus facilitating the introduction of the new detectors or types of detectors into the analysis framework. The operational details of the routines are suited to the specific requirements of particular detectors by adjusting the set of external input parameters. Pulse recognition, baseline calculation and the pulse shape fitting procedure are described. Special emphasis is put on their computational efficiency, since the most basic implementations of these conceptually simple methods are often computationally inefficient.Croatian Science Foundation - Project No. 168

    Pulse shape analysis of signals from BaF2 and CeF3 scintillators for neutron capture experiments

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    The scope of this work is to study the characteristics of BaF2 and CeF3 signals using fast digitizers, which allow the sampling of the signal at very high frequencies and the application of the fitting method for analysis of the recorded pulses. By this procedure particle identification and the reconstruction of pile-up events can be improved, while maintaining the energy and time-of-flight resolution as compared to traditional methods. The reliability of the technique and problems connected with data acquisition are discussed with respect to accurate measurements of neutron capture cross-sections
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