A fast ionization chamber for fission cross-section measurements at n_TOF Calviani, M.; Cennini, P.; Karadimos, D. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2008, Letnik:
594, Številka:
2
Journal Article
Recenzirano
An ionization chamber with fast timing properties was built at CERN for measuring fission cross-sections of minor actinides at the n_TOF neutron beam. The design of this new chamber and of the ...front-end electronics was optimized to match the innovative features of the n_TOF facility, in particular the high instantaneous neutron flux and low background. For the most radioactive isotopes, a special version of the chamber, designed according to the ISO2919 standards, was built in order to comply with the radioprotection requirements at CERN. The detector and front-end electronics are here described, together with the simulated and measured response to fission fragments and α-particles. The performances of the chamber during the first measurement campaign at n_TOF are presented, focusing in particular on the fast time response, the good background rejection capability, low-background and high detection efficiency.
A low background neutron flux monitor for the n_TOF facility at CERN Marrone, S.; Mastinu, P.F.; Abbondanno, U. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2004, Letnik:
517, Številka:
1
Journal Article
Recenzirano
A small-mass system has been developed for monitoring the flux of neutrons with energy up to 1
MeV at the new time-of-flight facility at CERN, n_TOF. The monitor is based on a thin Mylar foil with a
...6Li deposit, placed in the neutron beam, and an array of silicon detectors, placed outside the beam, for detecting the products of the
6Li(
n,
α)
3H reaction. The small amount of material on the beam ensures a minimal perturbation of the flux and minimizes the background related to scattered neutrons. Moreover, a further reduction of the
γ-ray background has been obtained by constructing the scattering chamber hosting the device in carbon fibre. A detailed description of the flux monitor is here presented, together with the characteristics of the device, in terms of efficiency, resolution and induced background. The use of the monitor in the measurement of neutron capture cross-sections at n_TOF is discussed.
The new neutron time-of-flight facility (n_TOF) has been built at CERN and is now operational. The facility is intended for the measurement of neutron induced cross-sections of relevance to ...Accelerator Driven Systems (ADS) and to fundamental physics. Neutrons are produced by spallation of the
20
GeV/c
proton beam, delivered by the Proton Synchrotron (PS), on a massive target of pure lead. A measuring station is placed at
≈185
m
from the neutron producing target, allowing high-resolution measurements. The facility was successfully commissioned with two campaigns of measurements, in November 2000 and April 2001. The main interest was concentrated in the physical parameters of the installation (neutron fluence and resolution function), along with the target behavior and various safety-related aspects. These measurements confirmed the expectations from Monte Carlo simulations of the facility, thus allowing to initiate the foreseen physics program.
Analysis of the FIC detector data at the n_TOF facility Karadimos, D.; Vlastou, R.; Ioannides, K. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
08/2010, Letnik:
268, Številka:
16
Journal Article
Recenzirano
Fission cross-section measurements with the Fast Ionization Chamber (FIC) at the CERN n_TOF facility were challenged by intense signals due to γ-rays and ultra-relativistic particles from the impact ...of the 20
GeV proton pulses on the neutron spallation target. A method for analyzing the data taken with Flash Analog to Digital Converters (FADC) was developed to treat these problems in an automated way to provide a reliable background subtraction and a fit routine for identifying fission events even at high energies. The analysis is illustrated at the example of the fission cross-section of
238U relative to that of
235U in the energy range from 40
keV to 300
MeV.
Activation Studies of the CERN n_TOF Target Brugger, M.; Cennini, P.; Ferrari, A. ...
Nuclear technology,
12/2009, Letnik:
168, Številka:
3
Journal Article, Conference Proceeding
Recenzirano
The n_TOF facility, a spallation neutron source, uses a pure lead target to produce neutrons with a 20-GeV proton beam extracted from the CERN Proton Synchrotron. After 4 yr of operation and ˜3 yr of ...cooling, the present spallation target is damaged and was moved to its provisional storage place in the n_TOF service gallery and will be later transferred to a Swiss repository. In this study, to deal with the removal and storage of the lead target, detailed isotope production and residual dose rate calculations were performed with the FLUKA Monte Carlo code. The study further includes a detailed analysis of three-dimensional residual dose rate fields around the target and through the installation pit. It addresses critical design parameters for the new target and successfully compares the simulation results to recently available measurement data. FLUKA allows residual dose rates to be calculated using two different approaches: a one-step approach that simultaneously takes into account production and decay (built-in) and a two-step approach that allows for flexible geometries between the isotope production and sampling of the decay products (customized). This work shows the clear advantage of performing Monte Carlo calculations prior to interventions and waste disposal and the importance of a detailed description of all the installation components, a complete chemical composition inventory, and a correct irradiation profile.
After a long run with the 3 Ton prototype at CERN, here is presented the new architecture of the Front-End Electronics for the 50 000 wires of the 600 Tons ICARUS Detector.
Scintillation efficiency of nuclear recoil in liquid xenon Arneodo, F; Baiboussinov, B; Badertscher, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2000, Letnik:
449, Številka:
1
Journal Article
Recenzirano
We present the results of a test done with a Liquid Xenon (LXe) detector for “Dark Matter” search, exposed to a neutron beam to produce nuclear recoil events simulating those which would be generated ...by WIMP's elastic scattering. The aim of the experiment was to measure directly the scintillation efficiency of nuclear recoil. The nuclear recoil considered in the test was in the tens of keV range. The ratio of measured visible energy over the true recoil energy was evaluated to be about 20%, in good agreement with the theoretical predictions.
The n_TOF spallation neutron facility is operating at CERN since 2001. Neutrons are produced with a very wide energy range, from thermal up to 1 GeV and with a very high instantaneous flux ...(105n/cm2/pulse at 200 m from target) thanks to the high intensity (7 × 1012 protons/pulse) and low repetition rate of the Proton Synchrotron (PS) which is delivering protons to a lead spallation target. The experimental area is located at 200 m from the target, resulting in a very good energy resolution and beam quality thanks to the adoption of an optimal collimation system. At the end of 2008 the n_TOF facility has resumed operation after a halt of 3 years due to technical issues. This contribution will outline the main physics results obtained by the facility since its inception in 1999, and show the importance of the measured nuclear data in the field of Nuclear Astrophysics and Nuclear Technology. Then it will present the future perspectives of the facility, aiming mainly in the direction of measuring highly radioactive samples, for which the facility has unique capabilities, with a lower background.
Detection of Cherenkov light emission in liquid argon Antonello, M.; Arneodo, F.; Badertscher, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2004, Letnik:
516, Številka:
2
Journal Article
Recenzirano
Detection of Cherenkov light emission in liquid argon has been obtained with an ICARUS prototype, during a dedicated test run at the Gran Sasso Laboratory external facility. Ionizing tracks from ...cosmic ray muons crossing the detector active volume have been collected in coincidence with visible light signals from a photo-multiplier (PMT) immersed in liquid argon. A 3D reconstruction of the tracks has been performed exploiting the ICARUS imaging capability. The angular distributions of the tracks triggered by the PMT signals show an evident directionality. By means of a detailed Monte Carlo simulation we show that the geometrical characteristics of the events are compatible with the hypothesis of Cherenkov light emission as the main source of the PMT signals.
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