Development and performance of the Fast Neutron Imaging Telescope for SNM detection

FNIT (the Fast Neutron Imaging Telescope), a detector with both imaging and energy measurement capabilities, sensitive to neutrons in the range 0.8-20 MeV, was initially conceived to study solar neutrons as a candidate design for the Inner Heliosphere Sentinel (IHS) spacecraft of NASA\u27s Solar Sentinels program and successively reconfigured to locate fission neutron sources. By accurately identifying the position of the source with imaging techniques and reconstructing the Watt spectrum of fission neutrons, FNIT can detect samples of special nuclear material (SNM), including heavily shielded and masked ones. The detection principle is based on multiple elastic neutron-proton scatterings in organic scintillators. By reconstructing n-p event locations and sequence and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron sources identified. We describe the design of the FNIT prototype and present its energy reconstruction and imaging performance, assessed by exposing FNIT to a neutron beam and to a Pu fission neutron source

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

SONNE, the SOlar NeutroN Experiment proposed for Solar Probe Plus, is designed to measure solar neutrons from 1-20 MeV and solar gammas from 0.5-10 MeV. SONNE is a double scatter instrument that employs imaging to maximize its signal-to-noise ratio by rejecting neutral particles from non-solar directions. Under the assumption of quiescent or episodic small-flare activity, one can constrain the energy content and power dissipation by fast ions in the low corona. Although the spectrum of protons and ions produced by nanoflaring activity is unknown, we estimate the signal in neutrons and γ−rays that would be present within thirty solar radii, constrained by earlier measurements at 1 AU. Laboratory results and simulations will be presented illustrating the instrument sensitivity and resolving power

Design optimization and performance capabilities of the fast neutron imaging telescope (FNIT)

We describe the design optimization process and performance characterization of a next generation neutron telescope, with imaging and energy measurement capabilities, sensitive to neutrons in the 1-20 MeV energy range. The response of the Fast Neutron Imaging Telescope (FNIT), its efficiency in neutron detection, energy resolution and imaging capabilities were characterized through a combination of lab tests and Monte Carlo simulations. Monte Carlo simulations, together with experimental data, are also being used in the development and testing of the image reconstruction algorithm. FNIT was initially conceived to study solar neutrons as a candidate instrument for the Inner Heliosphere Sentinel (IHS) spacecraft. However, the design of this detector was eventually adapted to locate Special Nuclear Material (SNM) sources for homeland security purposes, by detecting fission neutrons. In either case, the detection principle is based on multiple elastic neutron-proton scatterings in organic scintillator. By reconstructing event locations and measuring the recoil proton energies, the direction and energy spectrum of the primary neutron flux can be determined and neutron sources identified. This paper presents the most recent results arising from our efforts and outlines the performance of the FNIT detector

On-sky results of the adaptive optics MACAO for the new IR-spectrograph CRIRES at VLT

The adaptive optics MACAO has been implemented in 6 focii of the VLT observatory, in three different flavors. We present in this paper the results obtained during the commissioning of the last of these units, MACAO-CRIRES. CRIRES is a high-resolution spectrograph, which efficiency will be improved by a factor two at least for point-sources observations with a NGS brighter than R=15. During the commissioning, Strehl exceeding 60% have been observed with fair seeing conditions, and a general description of the performance of this curvature adaptive optics system is done.Comment: SPIE conference 2006, Advances in adaptive optics, 12 pages, 11 figure

Characterisation of candidate members of (136108) Haumea's family: II. Follow-up observations

From a dynamical analysis of the orbital elements of transneptunian objects (TNOs), Ragozzine & Brown reported a list of candidate members of the first collisional family found among this population, associated with (136108) Haumea (a.k.a. 2003 EL61). We aim to distinguish the true members of the Haumea collisional family from interlopers. We search for water ice on their surfaces, which is a common characteristic of the known family members. The properties of the confirmed family are used to constrain the formation mechanism of Haumea, its satellites, and its family. Optical and near-infrared photometry is used to identify water ice. We use in particular the CH4 filter of the Hawk-I instrument at the European Southern Observatory Very Large Telescope as a short H-band (Hs), the (J-Hs) colour being a sensitive measure of the water ice absorption band at 1.6 {\mu}m. Continuing our previous study headed by Snodgrass, we report colours for 8 candidate family members, including near-infrared colours for 5. We confirm one object as a genuine member of the collisional family (2003 UZ117), and reject 5 others. The lack of infrared data for the two remaining objects prevent any conclusion from being drawn. The total number of rejected members is therefore 17. The 11 confirmed members represent only a third of the 36 candidates. The origin of Haumea's family is likely to be related to an impact event. However, a scenario explaining all the peculiarities of Haumea itself and its family remains elusive.Comment: 8 pages, 4 figures, accepted for publication in A&

Characterisation of candidate members of (136108) Haumea's family

Ragozzine & Brown [2007] presented a list of candidate members of the first collisional family to be found among the trans-Neptunian Objects (TNOs), the one associated with (136108) Haumea (2003 EL61). We aim to identify which of the candidate members of the Haumea collisional family are true members, by searching for water ice on their surfaces. We also attempt to test the theory that the family members are made of almost pure water ice by using optical light-curves to constrain their densities. We use optical and near-infrared photometry to identify water ice, in particular using the (J - H_S) colour as a sensitive measure of the absorption feature at 1.6 micron. We use the CH_4 filter of the new Hawk-I instrument at the VLT as a short H-band (H_S) for this as it is more sensitive to the water ice feature than the usual H filter. We report colours for 22 candidate family members, including NIR colours for 15. We confirm that 2003 SQ317 and 2005 CB79 are family members, bringing the total number of confirmed family members to 10. We reject 8 candidates as having no water ice absorption based on our Hawk-I measurements, and 5 more based on their optical colours. The combination of the large proportion of rejected candidates and time lost to weather prevent us from putting strong constraints on the density of the family members based on the light-curves obtained so far; we can still say that none of the family members (except Haumea) require a large density to explain their light-curve.Comment: 9 pages, 5 figures, accepted for publication in A&

The TRAPPIST survey of southern transiting planets. I. Thirty eclipses of the ultra-short period planet WASP-43 b

We present twenty-three transit light curves and seven occultation light curves for the ultra-short period planet WASP-43 b, in addition to eight new measurements of the radial velocity of the star. Thanks to this extensive data set, we improve significantly the parameters of the system. Notably, the largely improved precision on the stellar density (2.41+-0.08 rho_sun) combined with constraining the age to be younger than a Hubble time allows us to break the degeneracy of the stellar solution mentioned in the discovery paper. The resulting stellar mass and size are 0.717+-0.025 M_sun and 0.667+-0.011 R_sun. Our deduced physical parameters for the planet are 2.034+-0.052 M_jup and 1.036+-0.019 R_jup. Taking into account its level of irradiation, the high density of the planet favors an old age and a massive core. Our deduced orbital eccentricity, 0.0035(-0.0025,+0.0060), is consistent with a fully circularized orbit. We detect the emission of the planet at 2.09 microns at better than 11-sigma, the deduced occultation depth being 1560+-140 ppm. Our detection of the occultation at 1.19 microns is marginal (790+-320 ppm) and more observations are needed to confirm it. We place a 3-sigma upper limit of 850 ppm on the depth of the occultation at ~0.9 microns. Together, these results strongly favor a poor redistribution of the heat to the night-side of the planet, and marginally favor a model with no day-side temperature inversion.Comment: 14 pages, 6 tables, 11 figures. Accepted for publication in A&

Repeated Human Exposure to Semivolatile Organic Compounds by Inhalation: Novel Protocol for a Nonrandomized Study.

peer reviewed[en] BACKGROUND: Semivolatile organic compounds (SVOCs) comprise several different chemical families used mainly as additives in many everyday products. SVOCs can be released into the air as aerosols and deposit on particulate matter during use by dispersion, evaporation, or abrasion. Phthalates are SVOCs of growing concern due to their endocrine-disrupting effects. Human data on the absorption, distribution, metabolism, and excretion (ADME) of these compounds upon inhalation are almost nonexistent. OBJECTIVE: The goal of this study is to develop a method for repeated inhalation exposures to SVOCs to characterize their ADME in humans. METHODS: We will use diethylhexyl phthalate (DEHP), a major indoor air pollutant, as a model SVOC in this novel protocol. The Swiss official Commission on Ethics in Human Research, Canton de Vaud, approved the study on October 14, 2020 (project-ID 2020-01095). Participants (n=10) will be repeatedly exposed (2 short daily exposures over 4 days) to isotope-labeled DEHP (DEHP-d4) to distinguish administered exposures from background exposures. DEHP-d4 aerosols will be generated with a small, portable, aerosol-generating device. Participants will inhale DEHP-d4-containing aerosols themselves with this device at home. Air concentrations of the airborne phthalates will be less than or equal to their occupational exposure limit (OEL). DEHP-d4 and its metabolites will be quantified in urine and blood before, during, and after exposure. RESULTS: Our developed device can generate DEHP-d4 aerosols with diameters of 2.5 μm or smaller and a mean DEHP-d4 mass of 1.4 (SD 0.2) μg per puff (n=6). As of May 2023, we have enrolled 5 participants. CONCLUSIONS: The portable device can be used to generate phthalate aerosols for repeated exposure in human studies. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/51020