The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest of all low-energy neutrino couplings. This ...mode of interaction offers new opportunities to study neutrino properties and leads to a miniaturization of detector size, with potential technological applications. We observed this process at a 6.7σ̃ confidence level, using a low-background, 14.6-kilogram CsINa scintillator exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the standard model for this process, were observed in high signal-to-background conditions. Improved constraints on nonstandard neutrino interactions with quarks are derived from this initial data set.
Autonomous radiation monitoring of small vessels Ziock, K.P.; Cheriyadat, A.; Fabris, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
10/2011, Letnik:
652, Številka:
1
Journal Article
Recenzirano
Small private vessels are one avenue by which nuclear materials may be smuggled across international borders. While one can contemplate using the land-based approach of radiation portal monitors on ...the navigable waterways that lead to many ports, these systems are ill-suited to the problem. In contrast to roadways, where lanes segregate vehicles, and motion is well controlled by inspection booths; channels, inlets, and rivers present chaotic traffic patterns populated by vessels of all sizes. A unique solution to this problem is based on a portal-less portal monitor designed to handle free-flowing traffic on roadways with up to five-traffic lanes. The instrument uses a combination of visible-light and gamma-ray imaging to acquire and link radiation images to individual vehicles. This paper presents the results of a recent test of the system in a maritime setting.
The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3 GeV/c) direct-photon yields from Au+Au collisions at sqrts_{NN}=39 and 62.4 GeV. For both beam energies the ...direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrts_{NN}=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1 GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5 GeV/c), but when results from different collision energies are compared, an additional sqrts_{NN}-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.
Scintillator-based detectors are among the most commonly used methods for detecting ionizing radiation. Scintillators provide a reliable, cost-effective, and simple way to make large-volume ...detectors. Furthermore, localizing the position of the interactions in three dimensions within the crystals is useful to a wide array of fields. The most straightforward way of doing this is to pair the crystal with a position-sensitive phototransducer (PT). This allows for measurement of the shape of the light spot at the PT plane. Using this information, various methods exist to localize the gamma-ray interaction in the crystal; however, the position resolution worsens the farther the event occurs from the PT plane. To improve on the localization ability, this work uses an optical coded-aperture shadow mask between the crystal and the PT. The recorded detector response is used in reconstructing the event over the entire depth of the crystal, and the "sharpest" reconstructed image gives an event's depth. The lateral position is given from the standard coded-aperture image reconstruction. Experimental results obtained by emulating a 26-mm-thick crystal using a thin 1-mm-thick NaI(Tl) crystal and different amounts of light pipe between the crystal and the PT plane achieved ~ 1 to 2-mm resolution in all three dimensions throughout most of the 26-mm-thick crystal.
Event localization in bulk scintillator crystals using coded apertures Ziock, K.P.; Braverman, J.B.; Fabris, L. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2015, Letnik:
784, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The localization of radiation interactions in bulk scintillators is generally limited by the size of the light distribution at the readout surface of the crystal/light-pipe system. By finding the ...centroid of the light spot, which is typically of order centimeters across, practical single-event localization is limited to ~2mm/cm of crystal thickness. Similar resolution can also be achieved for the depth of interaction by measuring the size of the light spot. Through the use of near-field coded-aperture techniques applied to the scintillation light, light transport simulations show that for 3-cm-thick crystals, more than a five-fold improvement (millimeter spatial resolution) can be achieved both laterally and in event depth. At the core of the technique is the requirement to resolve the shadow from an optical mask placed in the scintillation light path between the crystal and the readout. In this paper, experimental results are presented that demonstrate the overall concept using a 1D shadow mask, a thin-scintillator crystal and a light pipe of varying thickness to emulate a 2.2-cm-thick crystal. Spatial resolutions of ~1mm in both depth and transverse to the readout face are obtained over most of the crystal depth.
The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest of all low-energy neutrino couplings. This ...mode of interaction offers new opportunities to study neutrino properties and leads to a miniaturization of detector size, with potential technological applications. We observed this process at a 6.7s confidence level, using a low-background, 14.6-kilogram CsINa scintillator exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the standard model for this process, were observed in high signal-to-background conditions. Improved constraints on nonstandard neutrino interactions with quarks are derived from this initial data set.
We have developed a proof-of-concept prototype, rapid-deployment, gamma-ray portal monitor that can uniquely link the radiation signatures and visible-light images of vehicles in the system's field ...of view from the side of a multilane roadway. The instrument uses both visible-light and gamma-ray imaging to accomplish this. Vehicles entering the field of view of the visible-light imaging system are identified and tracked by an automated target acquisition and tracking software engine. The vehicle locations provided by this code are reported to the gamma-ray imager which uses them to locate the vehicles in the gamma-ray images and to collect the vehicle-specific radiation signatures from those images. Using this technique the gamma-ray data is integrated over the entire residence time of the vehicle in the gamma-ray imager field of view. The complete instrument comprises ~ 1-m 2 CsI(Na) detector area split between two units. The system has been designed to handle up to five-lanes of traffic at highway speeds, with one unit located on either side of the roadway. Because no equipment is required in the roadway, the instrument can be deployed without impacting the flow of traffic. The results of a test and evaluation campaign indicates that the system meets its design goal of detecting 37 MBq-class sources in any of five-lanes of traffic at up to 113 km/h.
We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central d+Au and minimum bias p+p collisions at sqrts_{NN}=200 GeV. The charged hadron ...is measured at midrapidity |η|<0.35, and the energy is measured at large rapidity (-3.7<η<-3.1, Au-going direction). An enhanced near-side angular correlation across |Δη|>2.75 is observed in d+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength v_{2} for inclusive charged hadrons at midrapidity up to p_{T}=4.5 GeV/c. We also present the measurement of v_{2} for identified π^{±} and (anti)protons in central d+Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calculations and measurements from p+Pb at sqrts_{NN}=5.02 TeV. The magnitude of the mass ordering in d+Au is found to be smaller than that in p+Pb collisions, which may indicate smaller radial flow in lower energy d+Au collisions.
Scintillator-based detectors are among the most commonly used methods for detecting ionizing radiation. Scintillators provide a reliable, cost-effective, and simple way to make large-volume ...detectors. Furthermore, localizing the position of the interactions in three dimensions within the crystals is useful to a wide array of fields. The most straightforward way of doing this is to pair the crystal with a position-sensitive phototransducer (PT). This allows for measurement of the shape of the light spot at the PT plane. Using this information, various methods exist to localize the gamma-ray interaction in the crystal; however, the position resolution worsens the farther the event occurs from the PT plane. To improve on the localization ability, this work uses an optical coded-aperture shadow mask between the crystal and the PT. The recorded detector response is used in reconstructing the event over the entire depth of the crystal, and the "sharpest" reconstructed image gives an event's depth. The lateral position is given from the standard coded-aperture image reconstruction. Experimental results obtained by emulating a 30-mm-thick crystal using a thin 1-mm-thick NaI(Tl) crystal and different amounts of light pipe between the crystal and the PT plane achieved ~1 to 2-mm resolution in all three dimensions throughout most of the 30-mm-thick crystal.
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