Results from the dynamic albedo of neutrons (DAN) passive mode experiment: Yellowknife Bay to Amargosa Valley (Sols 201–753)

On an Extensive Late Hydrologic Event in Gale Crater as Indicated by Water‐Rich Fracture Halos

“…(2013), Tate et al. (2015, 2018). In this work, we focus on the quantification of H from active neutrons and LIBS experiments, so we present only the raw count rates of passive data to show qualitative trends and demonstrate how geochemically‐unique rocks are identified during rover operations.…”

“…Tate et al. (2018) demonstrate that the GCR flux at the surface, as inferred from Radiation Assessment Detector (RAD) measurements, can vary by ∼25% over a 100 sol period, but can also maintain an ∼10% relative dynamic range for several hundred sols. This phenomenon is accounted for in the analysis of passive DAN data by cross‐calibrations with RAD (Tate et al., 2018).…”

“…(2018) demonstrate that the GCR flux at the surface, as inferred from Radiation Assessment Detector (RAD) measurements, can vary by ∼25% over a 100 sol period, but can also maintain an ∼10% relative dynamic range for several hundred sols. This phenomenon is accounted for in the analysis of passive DAN data by cross‐calibrations with RAD (Tate et al., 2018). Passive DAN experiments are also not time resolved, whereas active experiments contain time‐of‐flight information in addition to the two‐band energy resolution provided by the He 3 detectors.…”

“…Thus, passive DAN data are processed in a markedly different manner than that of active experiments. For more detailed information on processing passive DAN experiments and their sensitivities we refer the reader to Jun et al (2013), Tate et al (2015Tate et al ( , 2018.…”

Evidence for Multiple Diagenetic Episodes in Ancient Fluvial‐Lacustrine Sedimentary Rocks in Gale Crater, Mars

“…Lastly, the DAN instrument provides insight into the subsurface composition (e.g., Mitrofanov et al, 2012) and structure (e.g., Gabriel et al, 2018;Mitrofanov et al, 2016). With a~0.8-m scale spot size (FWHM) and maximum measurement depths between 45 and 70 cm, DAN detects low-energy neutrons allowing for changes in geochemistry, particularly changes in H, Cl, and Fe content, to be monitored along Curiosity's traverse (e.g., Gabriel et al, 2018;Litvak et al, 2016;Tate et al, 2015Tate et al, , 2018. APXS, ChemCam, SAM, and DAN data complement mineralogical data and allow the science team to monitor geochemical trends with stratigraphy (e.g., Gellert et al, 2015;L'Haridon et al, 2018;Mangold et al, 2018;Nachon et al, 2017;Tate et al, 2015Tate et al, , 2018.…”