Advanced characterization and simulation of SONNE: a fast neutron spectrometer for Solar Probe Plus

Woolf, Richard S.; Ryan, J. M.; Bloser, Peter F.; Bravar, U.; Flückiger, E. O.; Legere, Jason S.; MacKinnon, A. L.; Mallik, Procheta; McConnell, Mark L.; Pirard, B.

doi:10.1117/12.826425

Cited by 4 publications

(4 citation statements)

References 18 publications

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“…To detect 1–10 MeV neutrons with reasonable sensitivity, the distance of the neutron detector to the Sun must be substantially less than 1 AU. Measuring neutron spectra at a small detector‐Sun distance was the rationale for considering the inclusion of neutron detectors on planned missions to the inner heliosphere (e.g., Solar Orbiter and Solar Probe Plus) [ Feldman et al , ; Woolf et al , ; Lawrence et al , ]. Unfortunately, neutron detectors were not selected for either of these missions.…”

Section: Introductionmentioning

confidence: 99%

Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

et al. 2014

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[1] Data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Neutron Spectrometer (NS) have been used to identify energetic neutrons (0.5-8 MeV energy) associated with solar events that occurred on 4 June 2011. Multiple lines of evidence, including measurements from the NS and the MESSENGER Gamma-Ray Spectrometer, indicate that the detected neutrons have a solar origin. This evidence includes a lack of time-coincident, energetic (>45 MeV) charged particles that could otherwise create local neutrons from nearby spacecraft material and a lack of proton-induced gamma rays that should be seen if energetic protons were present. NS data cannot rule out the presence of lower-energy ions (<30 MeV) that can produce local neutrons. However, the ion spectral shape required to produce the measured neutron count rate locally is softer than any known ion spectral shape. The neutron energy spectrum shows a relative enhancement in the energy range 0.8-3 MeV compared with cosmic-ray-generated neutrons from the spacecraft or Mercury. The spectral shape of the measured neutron fluence spectrum is consistent with a previously modeled fluence spectrum of neutrons that originate at the Sun and are propagated through the MESSENGER spacecraft to the NS. These measurements provide strong evidence for a solar origin of the detected neutrons and suggest that a large number of low-energy threshold ion evaporation reactions were taking place on the Sun during the neutron event.

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Section: Introductionmentioning

confidence: 99%

Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

et al. 2014

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“…For the 10 35 /(4 π ) protons s −1 sr −1 implied by the MESSENGER NS measurements and an alpha/proton abundance of 0.2 used by MKS, this corresponds to at most 10 33 alphas s −1 sr −1 . Woolf et al [] estimate an energy imparted to the corona of 2.6 × 10 − 28 erg s −1 cm −2 for each alpha s −1 sr −1 . Thus, the MESSENGER measurements are consistent with an energy flux of 3 × 10 5 erg s −1 cm −2 due to alpha‐particle heating.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…The NS therefore provides a unique opportunity to measure and characterize the neutron and charged particle environment in this region. Indeed, it is likely to be the only neutron detector in the foreseeable future with this proximity to the Sun, as the Solar Probe Plus and Solar Orbiter payloads are not scheduled to include neutron detectors [ Lawrence et al , ; Woolf et al , ].…”

Section: Introductionmentioning

confidence: 99%

Neutrons and energetic charged particles in the inner heliosphere: Measurements of the MESSENGER Neutron Spectrometer from 0.3 to 0.85 AU

et al. 2015

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Energetic charged particle and neutron data from the Neutron Spectrometer (NS) on board the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft have been acquired for solar distances ranging from 0.3 to 0.85 AU. The NS is sensitive to ions with energies greater than 120 MeV/nucleon and has made the first measurements of these energetic ions in the inner heliosphere since the mid-1970s. The high-energy ion measurements are well correlated with Earth-based neutron monitor measurements, which themselves provide a measure of the solar modulation of galactic cosmic rays (GCRs). These measurements provide an explicit demonstration of the expected GCR solar modulation for solar distances to 0.3 AU. These NS data also represent the first interplanetary neutron measurements in the inner heliosphere. The time variability of the neutron measurements are driven by two primary effects: time variable production of neutrons from GCRs interacting with local spacecraft material and small count rate changes due to temperature-driven gain changes in the NS instrument. When these time-dependent variations are removed from the neutron measurements, there is no statistically significant variation of neutron count rates versus solar distance. These data are used to derive an upper limit on solar neutron production of 10 24 neutrons [0.5 < E < 9 MeV] sr À1 s À1 during quiescent periods.

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“…The FNIT also had applications in homeland security measuring fission neutrons. Later iterations of the FNIT and a scaled down version -Solar Neutron Experiment (SONNE) -used liquid scintillator filled cylindrical pillars arranged in a radially symmetric pattern [12,13].…”

Section: Previous Workmentioning

confidence: 99%

Model-based design evaluation of a compact, high-efficiency neutron scatter camera

Weinfurther

Mattingly

Brubaker

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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This paper presents the model-based design and evaluation of an instrument that estimates incident neutron direction using the kinematics of neutron scattering by hydrogen-1 nuclei in an organic scintillator. The instrument design uses a single, nearly contiguous volume of organic scintillator that is internally subdivided only as necessary to create optically isolated pillars, i.e., long, narrow parallelepipeds of organic scintillator. Scintillation light emitted in a given pillar is confined to that pillar by a combination of total internal reflection and a specular reflector applied to the four sides of the pillar transverse to its long axis. The scintillation light is collected at each end of the pillar using a photodetector, e.g., a microchannel plate photomultiplier (MCP-PM) or a silicon photomultiplier (SiPM). In this optically segmented design, the (x, y) position of scintillation light emission (where the x and y coordinates are transverse to the long axis of the pillars) is estimated as the pillar's (x, y) position in the scintillator "block", and the z-position (the position along the pillar's long axis) is estimated from the amplitude and relative timing of the signals produced by the photodetectors at each end of the pillar. The neutron's incident direction and energy is estimated from the (x, y, z)-positions of two sequential neutron-proton scattering interactions in the scintillator block using elastic scatter kinematics. For proton recoils greater than 1 MeV, we show that the (x, y, z)-position of neutron-proton scattering can be estimated with < 1 cm root-mean-squared [RMS] error and the proton recoil energy can be estimated with < 50 keV RMS error by fitting the photodetectors' response time history to models of optical photon transport within the scintillator pillars. Finally, we evaluate several alternative designs of this proposed single-volume scatter camera made of pillars of plastic scintillator (SVSC-PiPS), studying the effect of pillar dimensions, scintillator material (EJ-204, EJ-232Q and stilbene), and photodetector (MCP-PM vs. SiPM) response vs. time. We demonstrate that the most precise estimates of incident neutron direction and energy can be obtained using a combination of scintillator material with high luminosity and a photodetector with a narrow impulse response. Specifically, we conclude that an SVSC-PiPS constructed using EJ-204 (a high luminosity plastic scintillator) and an MCP-PM will produce the most precise estimates of incident neutron direction and energy.

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Advanced characterization and simulation of SONNE: a fast neutron spectrometer for Solar Probe Plus

Cited by 4 publications

References 18 publications

Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

Detection and characterization of 0.5–8 MeV neutrons near Mercury: Evidence for a solar origin

Neutrons and energetic charged particles in the inner heliosphere: Measurements of the MESSENGER Neutron Spectrometer from 0.3 to 0.85 AU

Model-based design evaluation of a compact, high-efficiency neutron scatter camera

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