Abstract
In neutron time-of-flight (nTOF) experiments a pulsed neutron beam travels a predetermined distance before reaching the sample under examination. The problem of reconstructing the primary ...neutron spectrum from the measured one with this technique is discussed in this work. A solution is presented employing the response matrix of the neutron detector and an unfolding procedure.
This paper describes the characterization of commercially available plastic scintillation detectors to be used as an active shield or veto system to reduce the neutron background resulting from ...atmospheric muon interactions in low-level nuclear waste assay systems. The shield consists of an array of scintillation detectors surrounding a neutron detection system. Scintillation detectors with different thicknesses are characterized for their response to gamma rays, neutrons, and muons. Response functions to gamma rays were determined and measured in the energy range from 0.6 MeV to 6.0 MeV using radionuclide sources. Neutron response functions were derived from results of time-of-flight measurements at the Van de Graaff accelerator of the INFN Legnaro and from measurements with quasi mono-energetic neutron beams produced at the Van de Graaff accelerator of the JRC Geel. From these data, the light output and resolution functions for protons and electrons were derived. The response to muons was verified by background measurements, i.e. without the presence of any neutron or gamma source. It was found that the muon peak is more pronounced when the detectors are placed horizontally. The results indicate that a scintillator with a minimum thickness of 20 mm is needed to separate events due to atmospheric muons from natural gamma ray background, and contributions due to neutron production in nuclear waste based on only the total energy deposition in the detector. In addition, it was shown that muons can be identified with a coincidence pattern when the detectors are stacked. The effectiveness of the proposed system was demonstrated based on muon induced spallation reactions in a lead sample.
LINUS is a project at the INFN Legnaro National Laboratories (LNL, Italy) to create a suite of different neutron sources (LSNS, NEPIR, SLOWNE) driven by existing accelerators. LSNS, driven by a 40 ...mA, 5 MeV proton RFQ, will use Li and Be targets to deliver cold, thermal, epithermal and fast neutrons. The SPES high current (0.75 mA), 70 MeV proton cyclotron will drive the NEPIR and SLOWNE facilities. NEPIR will alternatively deliver quasi mono-energetic neutrons with energy peak down to 20 MeV, and a neutron beam with a continuous energy distribution similar to that of neutrons present in the Earth atmosphere in the accessible energy range. SLOWNE is an intense neutron source for applications outside the LSNS range.
Status of the SPES Exotic Beam Facility Comunian, M; Andrighetto, A; Antonini, P ...
Journal of physics. Conference series,
01/2020, Letnik:
1401, Številka:
1
Journal Article
Recenzirano
Odprti dostop
At Legnaro National Laboratories of INFN is under construction a Rare Isotope Facility called "Selective Production of Exotic Species" (SPES) based on a 35-70 MeV proton cyclotron, able to deliver ...two beams with a total current up to 0.75 mA, an ISOL fission target station and an existing ALPI superconducting accelerator as a post accelerator (up to 10 MeV/u for A/q=7). The paper will cover notably: the high-resolution mass separator, the CW RFQ (80 MHz, 727 keV/u, with internal bunching), the 1+ low energy transfer line and the injection line from Charge Breeder to ALPI under installation.
SPES (Selective Production of Exotic Species) is an ISOL type facility for production and post-acceleration of exotic nuclei for forefront research in nuclear physics. Radioactive (RA) species (A = ...80÷160) will be produced by fissions induced by a proton beam impinging on an UCx target: the proton beam will be delivered by a commercial cyclotron with a 40 MeV maximum energy and a 0.25 mA maximum current. The RA species, extracted from the Target-Ion-Source system as a 1+ beam, will be cooled in a RFQ (radiofrequency quadrupole) beam cooler (RFQ-BC) and purified from the isobars contaminants through a High Resolution Mass Separator (HRMS). Post-acceleration will be performed via an ECR-based charge breeder, delivering the obtained q+ RA beam to a being built CW RFQ and to the being upgraded superconducting (sc) linac ALPI (up to 10 MeV/A for a mass-to-charge ratio A/q = 7).
(33)S is a stable isotope of sulfur for which the emission of an α-particle is the dominant exit channel for neutron-induced reactions. In this work the enhancement of both the absorbed and the ...equivalent biologically weighted dose in a BNCT treatment with 13.5keV neutrons, due to the presence of (33)S, has been tested by means of Monte Carlo simulations. The kerma-fluence factors for the ICRU-4 tissue have been calculated using standard weighting factors. The simulations depend crucially on the scarce (33)S(n,α)(30)Si cross-section data. The presence of a high resonance at 13.5keV was established by previous authors providing discrepant resonance parameters. No experimental data below 10keV are available. All of this has motivated a proposal of experiment at the n_TOF facility at CERN. A setup was designed and tested in 2011. Some results of the successful test will be shown. The experiment is scheduled for the period November to December 2012.
.
The SPES Radioactive Ion Beam (RIB) facility, now in the construction phase at INFN-LNL, has the aim to provide high-intensity and high-quality beams of neutron-rich nuclei for nuclear physics ...research as well as to develop an interdisciplinary research center based on the cyclotron proton beam. The SPES system is based on a dual-exit high-current cyclotron, with tunable proton beam energy 35-70MeV and 0.20-0.75mA. The first exit is used as proton driver to supply an ISOL system with an UCx Direct Target able to sustain a power of 10kW. The expected fission rate in the target is of the order of
fissions per second. The exotic isotopes will be re-accelerated by the ALPI superconducting LINAC at energies of 10
A
MeV and higher, for masses around
amu, with an expected beam intensity of
-
pps. The second exit will be used for applied physics: radioisotope production for medicine and neutrons for material studies. Fast neutron spectra will be produced by the proton beam interaction with a conversion target. A production rate in excess of
n/s can be achieved: this opens up the prospect of a high-flux neutron irradiation facility (NEPIR) to produce both discrete and continuous energy neutrons. A direct proton beam line is also envisaged. NEPIR and the direct proton line would dramatically increase the wide range of irradiation facilities presently available at LNL. We also present LENOS, a proposed project dedicated to accurate neutron cross-sections measurements using intense, well-characterized, broad energy neutron beams. Other activities already in operation at LNL are briefly reviewed: the SIRAD facility for proton and heavy-ion irradiation at the TANDEM-ALPI accelerator and the BELINA test facility at CN van de Graaff accelerator.
The need of neutron capture cross section measurements for astrophysics motivates present work, where calculations to generate stellar neutron spectra at different temperatures are performed. The ...accelerator-based (7)Li(p,n)(7)Be reaction is used. Shaping the proton beam energy and the sample covering a specific solid angle, neutron activation for measuring stellar-averaged capture cross section can be done. High-quality Maxwell-Boltzmann neutron spectra are predicted. Assuming a general behavior of the neutron capture cross section a weighted fit of the spectrum to Maxwell-Boltzmann distributions is successfully introduced.
Pulse shape analysis of liquid scintillators for neutron studies Marrone, S; Cano-Ott, D; Colonna, N ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
09/2002, Letnik:
490, Številka:
1
Journal Article
Recenzirano
The acquisition of signals from liquid scintillators with Flash ADC of high sampling rate
(1
GS/
s)
has been investigated. The possibility to record the signal waveform is of great advantage in ...studies with γ's and neutrons in a high count-rate environment, as it allows to easily identify and separate pile-up events. The shapes of pulses produced by γ-rays and neutrons have been studied for two different liquid scintillators, NE213 and C
6D
6. A 1-parameter fitting procedure is proposed, which allows to extract information on the particle type and energy. The performance of this method in terms of energy resolution and n/γ discrimination is analyzed, together with the capability to identify and resolve pile-up events.
We present some open questions in nucleosynthesis focused on the measurement of relevant neutron capture cross-sections and on new experimental methods. We review the recent super(63)Ni(n, gamma ) ...experiment carried out at the n_TOF facility at CERN and its astrophysical implications as well as future experiments and opportunities at n_TOF. We argue some improvements in the measurement of cross-sections by activation arising from a new method for the generation of stellar neutron spectra. We show preliminary results of the experimental validation of the method. We discuss the astrophysical implications of the super(181)Ta(n, gamma ) stellar cross-section measured with this method. Finally, we describe challenging experiments consisting of in situ radioactive ion beams and stellar neutron beams.
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