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The single-volume scatter camera

Proceedings of SPIE - The International Society for Optical Engineering

Manfredi, Juan J.; Adamek, Evan; Brown, Joshua A.; Brubaker, Erik B.; Cabrera-Palmer, Belkis C.; Cates, Joshua; Dorrill, Ryan; Druetzler, Andrew; Elam, Jeff; Feng, Patrick L.; Folsom, Micah; Galindo-Tellez, Aline; Goldblum, Bethany L.; Hausladen, Paul; Kaneshige, Nathan; Keefe, Kevin P.; Laplace, Thibault A.; Learned, John G.; Mane, Anil; Marleau, Peter M.; Mattingly, John; Mishra, Mudit; Moustafa, Ahmed; Nattress, Jason; Nishimura, Kurtis; Steele, John T.; Sweany, Melinda; Weinfurther, Kyle J.; Ziock, Klaus P.

The multi-institution Single-Volume Scatter Camera (SVSC) collaboration led by Sandia National Laboratories (SNL) is developing a compact, high-efficiency double-scatter neutron imaging system. Kinematic emission imaging of fission-energy neutrons can be used to detect, locate, and spatially characterize special nuclear material. Neutron-scatter cameras, analogous to Compton imagers for gamma ray detection, have a wide field of view, good event-by-event angular resolution, and spectral sensitivity. Existing systems, however, suffer from large size and/or poor efficiency. We are developing high-efficiency scatter cameras with small form factors by detecting both neutron scatters in a compact active volume. This effort requires development and characterization of individual system components, namely fast organic scintillators, photodetectors, electronics, and reconstruction algorithms. In this presentation, we will focus on characterization measurements of several SVSC candidate scintillators. The SVSC collaboration is investigating two system concepts: the monolithic design in which isotropically emitted photons are detected on the sides of the volume, and the optically segmented design in which scintillation light is channeled along scintillator bars to segmented photodetector readout. For each of these approaches, we will describe the construction and performance of prototype systems. We will conclude by summarizing lessons learned, comparing and contrasting the two system designs, and outlining plans for the next iteration of prototype design and construction.

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Current Status of an Optically-Segmented Single-Volume Scatter Camera for Neutron Imaging

Brown, J.AB.; Brubaker, Erik B.; Dorril, R D.; Druetzler, A D.; Elam, J E.; Febbraro, M F.; Feng, Patrick L.; Folsom, Michael W.; Galino-Tellez, A G.; Goldblum, B.LG.; Hausladen, P H.; Kaneshige, N K.; Keffe, K K.; Laplace, T, A.; Learned, J.G.L.; Mane, A M.; Manfredi, J M.; Marleau, Peter M.; Mattingly, J M.; Mishra, Mishra; Almanza-Madrid, Rene A.; Moustafa, A M.; Nattress, J N.; Steele, John T.; Sweany, Melinda; Weinfurther, K W.; Ziock, K.Z.

Abstract not provided.

Interaction position, time, and energy resolution in organic scintillator bars with dual-ended readout

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

Sweany, Melinda; Galindo-Tellez, A.; Brown, J.; Brubaker, Erik B.; Dorrill, R.; Druetzler, A.; Kaneshige, N.; Learned, J.; Nishimura, K.; Bae, W.

We report on the position, timing, and energy resolution of a range of plastic scintillator bars and reflector treatments using dual-ended silicon photomultiplier readout. These measurements are motivated by the upcoming construction of an optically segmented single-volume neutron scatter camera, in which neutron elastic scattering off of hydrogen is used to kinematically reconstruct the location and energy of a neutron-emitting source. For this application, interaction position resolutions of about 10 mm and timing resolutions of about 1 ns are necessary to achieve the desired efficiency for fission-energy neutrons. The results presented here indicate that this is achievable with an array of 5×5×190mm 3 bars of EJ-204 scintillator wrapped in Teflon tape, read out with SensL's J-series 6×6mm 2 silicon photomultipliers. With two independent setups, we also explore the systematic variability of the position resolution, and show that, in general, using the difference in the pulse arrival time at the two ends is less susceptible to systematic variation than using the log ratio of the charge amplitude of the two ends. Finally, we measure a bias in the absolute time of interactions as a function of position along the bar: the measured interaction time for events at the center of the bar is ∼100 ps later than interactions near the SiPM.

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Extension of the neutron scatter camera sensitivity to the ∼ 10-200 MeV neutron energy range

Review of Scientific Instruments

Cabrera-Palmer, Belkis C.; Brubaker, Erik B.; Gerling, Mark D.; Reyna, David R.

The Neutron Scatter Camera (NSC) is a neutron spectrometer and imager that has been developed and improved by the Sandia National Laboratories for several years. Built for special nuclear material searches, the instrument was configured by the design to reconstruct neutron sources within the fission energy range 1-10 MeV. In this work, we present modifications that attempt to extend the NSC sensitivity to neutron energies in the range ∼10-200 MeV and discuss the corresponding consequences for the event processing. We present simulation results that manifest important aspects of the NSC response to those intermediate energy neutrons. The simulation results also evidence that the instrument's spectroscopic capabilities severely deteriorate at those energies, mainly due to the uncertainties in measuring energy, time, and distance between the two neutron scattering interactions. This work is motivated by the need to characterize neutron fluxes at particle accelerators as they may represent important backgrounds for neutrino experiments.

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SCEMA: A high channel density electronics module for fast waveform capture

Journal of Instrumentation

Steele, J.; Brown, J.A.; Brubaker, Erik B.; Nishimura, K.

The development of fast, highly pixelated photodetectors with single-photon sensitivity has the potential to enable a variety of new radiation detection concepts. Systems that desire to employ these detectors without loss of information demand waveform digitization with high sampling rates. Switched capacitor arrays provide a low-cost, low-power, compact solution to fast readout with high channel density. The Sandia Laboratories Compact Electronics for Modular Acquisition (SCEMA) was developed to meet these demands. A single module employs two domino ring sampling switched capacitor arrays (DRS4) [1] to provide 16 channels of up to 5 GS/s waveform digitization. This paper presents an overview of the board design and function. Calibration procedures for the module are discussed. Finally, temporal resolution tests are presented demonstrating the module's viability as readout for high fidelity temporal measurements of single photons in suitable photodetectors.

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Progress toward a compact high-efficiency neutron scatter camera

Brown, Joshua A.; Brubaker, Erik B.; Cabrera-Palmer, Belkis C.; Druetzler, Andy D.; Elam, Jeff W.; Febbraro, Michael F.; Feng, Patrick L.; Folsom, Micah F.; Goldblum, Bethany L.; Hausladen, Paul H.; Kaneshige, Nate K.; Laplace, Thibault L.; Learned, John L.; Mane, Anil M.; Marleau, Peter M.; Mattingly, John M.; Mishra, Mudit M.; Nishimura, Kurtis N.; Steele, John T.; Sweany, Melinda; Ziock, Klaus Z.

Abstract not provided.

On the relationship between scintillation anisotropy and crystal structure in pure crystalline organic scintillator material

IEEE Transactions on Nuclear Science

Schuster, Patricia; Feng, Patrick L.; Brubaker, Erik B.

The scintillation anisotropy effect for proton recoil events has been investigated in five pure organic crystalline materials: Anthracene, trans-stilbene, p-terphenyl, bibenzyl, and diphenylacetylene (DPAC). These measurements include the characterization of the scintillation response for one hemisphere of proton recoil directions in each crystal. In addition to standard measurements of the total light output and pulse shape at each angle, the prompt and delayed light anisotropies are analyzed, allowing for the investigation of the singlet and triplet molecular excitation behaviors independently. This paper provides new quantitative and qualitative observations that make progress toward understanding the physical mechanisms behind the scintillation anisotropy. These measurements show that the relationship between the prompt and delayed light anisotropies is correlated with a crystal structure, as it changes between the pi-stacked crystal structure materials (anthracene and p-terphenyl) and the herringbone crystal structure materials (stilbene, bibenzyl, and DPAC). The observations are consistent with a model in which there are preferred directions of kinetic processes for the molecular excitations. These processes and the impact of their directional dependences on the scintillation anisotropy are discussed.

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Results 26–50 of 174
Results 26–50 of 174