149 research outputs found
Suitability of high-pressure xenon as scintillator for gamma ray spectroscopy
In this paper we report the experimental study of high-pressure xenon used as
a scintillator, in the context of developing a gamma ray detector. We measure a
light yield near 2 photoelectrons per keV for xenon at 40 bar. Together with
the light yield, we also measured an energy resolution of ~9% (FWHM) at 662
keV, dominated by the statistical fluctuations in the number of photoelectrons.Comment: 15 pages, 11 figure
A First Comparison of the responses of a He4-based fast-neutron detector and a NE-213 liquid-scintillator reference detector
A first comparison has been made between the pulse-shape discrimination
characteristics of a novel He-based pressurized scintillation detector
and a NE-213 liquid-scintillator reference detector using an Am/Be mixed-field
neutron and gamma-ray source and a high-resolution scintillation-pulse
digitizer. In particular, the capabilities of the two fast neutron detectors to
discriminate between neutrons and gamma-rays were investigated. The NE-213
liquid-scintillator reference cell produced a wide range of scintillation-light
yields in response to the gamma-ray field of the source. In stark contrast, due
to the size and pressure of the He gas volume, the He-based
detector registered a maximum scintillation-light yield of 750~keV to
the same gamma-ray field. Pulse-shape discrimination for particles with
scintillation-light yields of more than 750~keV was excellent in the
case of the He-based detector. Above 750~keV its signal was
unambiguously neutron, enabling particle identification based entirely upon the
amount of scintillation light produced.Comment: 23 pages, 7 figures, Nuclear Instruments and Methods in Physics
Research Section A review addresse
New Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities
The electromagnetic polarizabilities of the nucleon are fundamental
properties that describe its response to external electric and magnetic fields.
They can be extracted from Compton-scattering data --- and have been, with good
accuracy, in the case of the proton. In contradistinction, information for the
neutron requires the use of Compton scattering from nuclear targets. Here we
report a new measurement of elastic photon scattering from deuterium using
quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden.
These first new data in more than a decade effectively double the world
dataset. Their energy range overlaps with previous experiments and extends it
by 20 MeV to higher energies. An analysis using Chiral Effective Field Theory
with dynamical \Delta(1232) degrees of freedom shows the data are consistent
with and within the world dataset. After demonstrating that the fit is
consistent with the Baldin sum rule, extracting values for the isoscalar
nucleon polarizabilities and combining them with a recent result for the
proton, we obtain the neutron polarizabilities as \alpha_n = [11.55 +/-
1.25(stat) +/- 0.2(BSR) +/- 0.8(th)] X 10^{-4} fm^3 and \beta_n = [3.65 -/+
1.25(stat) +/- 0.2(BSR) -/+ 0.8(th)] X 10^{-4} fm3, with \chi^2 = 45.2 for 44
degrees of freedom.Comment: 6 pages, 3 figures, comments from Physical Review Letters Referees
addresse
Tagging fast neutrons from an 241Am/9Be source
We report on an investigation of the fast-neutron spectrum emitted by
241Am/9Be. Well-understood shielding, coincidence, and time-of-flight
measurement techniques are employed to produce a continuous, polychromatic,
energy-tagged neutron beam.Comment: 17 pages, 7 figures, submitted to Journal of Applied Radiation and
Isotope
Simulation of the Response of the Solid State Neutron Detector for the European Spallation Source
The characteristics of the Solid-state Neutron Detector, under development
for neutron-scattering measurements at the European Spallation Source, have
been simulated with a Geant4-based computer code. The code models the
interations of thermal neutrons and ionising radiation in the 6Li-doped
scintillating glass of the detector, the production of scintillation light and
the transport of optical, scintillation photons through the the scintillator,
en route to the photo-cathode of the attached multi-anode photomultiplier.
Factors which affect the optical-photon transport, such as surface finish,
pixelation of the glass sheet, provision of a front reflector and optical
coupling media are compared. Predictions of the detector response are compared
with measurements made with neutron and gamma-ray sources, a collimated alpha
source and finely collimated beams of 2.5 MeV protons and deuterons.Comment: Preprint 22 pages, 12 figures, published in NIM
Asynchronous Testing of Synchronous Components in GALS Systems
International audienceGALS (Globally Asynchronous Locally Synchronous) systems, such as the Internet of Things or autonomous cars, integrate reactive synchronous components that interact asynchronously. The complexity induced by combining synchronous and asynchronous aspects makes GALS systems difficult to develop and debug. Ensuring their functional correctness and reliability requires rigorous design methodologies, based on formal methods and assisted by validation tools. In this paper we propose a testing methodology for GALS systems integrating: (1) synchronous and asynchronous concurrent models; (2) functional unit testing and behavioral conformance testing; and (3) various formal methods and their tool equipments. We leverage the conformance test generation for asynchronous systems to automatically derive realistic scenarios (input constraints and oracle), which are necessary ingredients for the unit testing of individual synchronous components, and are difficult and error-prone to design manually. We illustrate our approach on a simple, but relevant example inspired by autonomous cars
Response of a Li-glass/multi-anode photomultiplier detector to collimated thermal-neutron beams
The response of a position-sensitive Li-glass scintillator detector being
developed for thermal-neutron detection with 6 mm position resolution has been
investigated using collimated beams of thermal neutrons. The detector was moved
perpendicularly through the neutron beams in 0.5 to 1.0 mm horizontal and
vertical steps. Scintillation was detected in an 8 X 8 pixel multi-anode
photomultiplier tube on an event-by-event basis. In general, several pixels
registered large signals at each neutron-beam location. The number of pixels
registering signal above a set threshold was investigated, with the
maximization of the single-hit efficiency over the largest possible area of the
detector as the primary goal. At a threshold of ~50% of the mean of the
full-deposition peak, ~80% of the events were registered in a single pixel,
resulting in an effective position resolution of ~5 mm in X and Y. Lower
thresholds generally resulted in events demonstrating higher pixel
multiplicities, but these events could also be localized with ~5 mm position
resolution.Comment: 23 pages, 8 figure
Light-yield response of liquid scintillators using 2–6 MeV tagged neutrons
Knowledge of the neutron light-yield response is crucial to the understanding of scintillator-based neutron detectors. In this work, neutrons from 2–6MeV have been used to study the scintillation light-yield response of the liquid scintillators NE 213A, EJ 305, EJ 331 and EJ 321P using event-by-event waveform digitization. Energy calibration was performed using a GEANT4 model to locate the edge positions of the Compton distributions produced by gamma-ray sources. The simulated light yield for neutrons from a PuBe source was compared to measured recoil proton distributions, where neutron energy was selected by time-of-flight. This resulted in an energy-dependent Birks parameterization to characterize the non-linear response to the lower energy neutrons. The NE 213A and EJ 305 results agree very well with existing data and are reproduced nicely by the simulation. New results for EJ 331 and EJ 321P, where the simulation also reproduces the data well, are presented
Compton Scattering from \u3csup\u3e12\u3c/sup\u3eC Using Tagged Photons in the Energy Range 65–115 MeV
Elastic scattering of photons from 12C has been investigated using quasimonoenergetic tagged photons with energies in the range 65–115 MeV at laboratory angles of 60∘, 120∘, and 150∘ at the Tagged-Photon Facility at the MAX IV Laboratory in Lund, Sweden. A phenomenological model was employed to provide an estimate of the sensitivity of the 12C(γ,γ)12C cross section to the bound-nucleon polarizabilities
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