528 research outputs found
The neutron time-of-flight facility n-TOF at CERN: Phase II
Neutron-induced reactions are studied at the neutron time-of-flight facility n-TOF at CERN. The facility uses 6∼ns wide pulses of 20 GeV/c protons impinging on a lead spallation target. The large neutron energy range and the high instantaneous neutron flux combined with high resolution are among the key characteristics of the facility. After a first phase of data taking during the period 2001-2004, the facility has been refurbished with an upgraded spallation target and cooling system for a second phase of data taking which started in 2009. Since 2010, the experimental area at 185 m where the neutron beam arrives, has been modified into a worksector of type A, allowing the extension of the physics program to include neutron-induced reactions on radioactive isotopes
Pulse processing routines for neutron time-of-flight data
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.Comment: 13 pages, 10 figures, 5 table
Observation of large scissors resonance strength in actinides
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
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
Neutron transmission and capture of 241Am
A set of neutron transmission and capture experiments based on the Time Of Flight (TOF) technique, were performed in order to determine the 241Am capture cross section in the energy range from 0.01 eV to 1 keV. The GELINA facility of the Institute for Reference Materials and Measurements (IRMM) served as the neutron source. A pair of C6D6 liquid scintillators was used to register the prompt gamma rays emerging from the americium sample, while a Li-glass detector was used in the transmission setup. Results from the capture and transmission data acquired are consistent with each other, but appear to be inconsistent with the evaluated data files. Resonance parameters have been derived for the data up to the energy of 100 eV.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard
Scissors resonance in the quasi-continuum of Th, Pa and U isotopes
The gamma-ray strength function in the quasi-continuum has been measured for
231-233Th, 232,233Pa and 237-239U using the Oslo method. All eight nuclei show
a pronounced increase in gamma strength at omega_SR approx 2.4 MeV, which is
interpreted as the low-energy M1 scissors resonance (SR). The total strength is
found to be B_SR = 9-11 mu_N^2 when integrated over the 1 - 4 MeV gamma-energy
region. The SR displays a double-hump structure that is theoretically not
understood. Our results are compared with data from (gamma, gamma') experiments
and theoretical sum-rule estimates for a nuclear rigid-body moment of inertia.Comment: 11 pages, 9 figure
Design study for a new spallation target of the n_TOF facility at CERN
The n_TOF facility is a time of flight spectrometer dedicated to measuring neutron capture and fission cross sections. The neutron source consists on a lead target bombarded by a high energetic proton beam. After finishing a successful period of data taking by the end of 2004, it has been decided to upgrade the neutron spallation source with a cladded target. In this study, Monte Carlo simulations are reported for the assessment and comparison of the neutron and gamma fluxes from different target configurations. In addition, the plans for a second vertical measuring station with a flight path of 20 m above the spallation target have been considered in the simulations as well. Results for the energy deposition and the target heating are also presented
Measurement of the 242Pu(n,f) cross section at n_TOF
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
New developments in Micromegas Microbulk detectors
A new Micromegas manufacturing technique, based on kapton etching technology,
has been recently developed, improving the uniformity and stability of this
kind of readouts. Excellent energy resolutions have been obtained, reaching 11%
FWHM for the 5.9 keV photon peak of 55Fe source and 1.8% FWHM for the 5.5 MeV
alpha peak of the 241Am source. The new detector has other advantages like its
flexible structure, low material and high radio-purity. The two actual
approaches of this technique will be described and the features of these
readouts in argon-isobutane mixtures will be presented. Moreover, the low
material present in the amplification gap makes these detectors approximate the
Rose and Korff model for the avalanche amplification, which will be discussed
for the same type of mixtures. Finally, we will present several applications of
the microbulk technique.Comment: To be published in the Proceedings of the TIPP2011 conference
(Physics Procedia
Neutron cross-sections for advanced nuclear systems : The n-TOF project at CERN
© Owned by the authors, published by EDP Sciences, 2014 This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedThe 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.Peer reviewedFinal Published versio
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