RESUMEN
This article reports on the development of thin diamond detectors and their characterization for their application in temporal profile measurements of subnanosecond ion bunches. Two types of diamonds were used: a 20 µm thin polycrystalline chemical vapor deposited (CVD) diamond and a membrane with a thickness of (5 ± 1) µm etched out of a single crystal (sc) CVD diamond. The combination of a small detector electrode and an impedance matched signal outlet leads to excellent time response properties with a signal pulse resolution (FWHM) of τ = (113 ± 11) ps. Such a fast diamond detector is a perfect device for the time of flight measurements of MeV ions with bunch durations in the subnanosecond regime. The scCVD diamond membrane detector was successfully implemented within the framework of the laser ion generation handling and transport project, in which ion beams are accelerated via a laser-driven source and shaped with conventional accelerator technology. The detector was used to measure subnanosecond proton bunches with an intensity of 108 protons per bunch.
RESUMEN
Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.
