Next‐generation solid‐state detectors for charged particle spectroscopy

Abstract

The performance of silicon avalanche photodiodes (APDs) and single crystal chemical vapor deposit diamond detectors (DDs) is reviewed in comparison with conventional silicon‐based solid‐state detectors (SSDs) from the perspective of space plasma applications. Although the low‐energy threshold and the energy resolution are equivalent to SSDs, DDs offer a high radiation tolerance and very low leakage currents due to a wider band gap than silicon. In addition, DDs can operate at higher temperatures, are insensitive to light (>226 nm), and are capable of timing analysis due to the higher intrinsic carrier mobility. APDs also offer several advantageous features. Specifically, APDs have a lower energy threshold (<0.9 keV) and a higher energy resolution (<0.7 keV full width at half maximum at room temperature), along with a linear response due to a strong electric field causing signal amplifications within the detector. Therefore, APDs can be used to detect lower energy particles, covering a larger portion of the energy spectrum than conventional SSDs. Further, the strong internal electric field gives them a subnanosecond response time by the charge mobility saturation, allowing them to make precise timing measurements of ions. These novel detector techniques can be potentially applied to improve the measurements of suprathermal particles, whose energies lie between typical ranges of conventional sensors for low‐energy plasmas and energetic particles. Although the origin and evolution of the suprathermal particles are the key to understanding the acceleration and heating processes in space plasma, they are not well understood due to the technical difficulties of making the measurement.

Medium-energy particle experiments—electron analyzer (MEP-e) for the exploration of energization and radiation in geospace (ERG) mission

“…Although an in-flight precise evaluation of an absolute efficiency is difficult, such a high value and moderate energy dependence ensure a high reliability compared to the MCPs and CEMs, and these are the benefits of using the APD. The APD also has the advantage over conventional solid-state detectors of measuring electrons below < 30 keV, because its internal gain provides a higher signal-to-noise ratio (Ogasawara et al 2005(Ogasawara et al , 2006(Ogasawara et al , 2008(Ogasawara et al , 2016Kasahara et al 2010Kasahara et al , 2012. Figure 7 shows APDs mounted azimuthally on a board with resisters and capacitors.…”

Properties of suprathermal electrons associated with discrete auroral arcs

“…MESP measured populations of precipitating electrons from ∼3 keV to 120 keV in the auroral ionosphere with avalanche photodiodes (APDs) [see Ogasawara et al, 2016a] and an SSD. MESP employs a permanent magnet filter with a light tight structure to select electrons with proper energies guided to the detectors.…”

“…Therefore, it has been hard to reliably distinguish between Maxwellian and kappa distributions using conventional plasma and energetic particle techniques [e.g., Wing and Newell, 1998] in the higher ranges. Recently, the Medium-energy Electron SPectrometer (MESP) has been developed with a novel detection technique [Ogasawara et al, 2016a] dedicated to measure suprathermal electrons in the auroral ionosphere and has successfully observed suprathermal electrons in the ionosphere [Ogasawara et al, 2016b] with unprecedented electron energy acceptance range and high geometric factor and provided new aspects of precipitating electrons.…”

Interstellar Mapping and Acceleration Probe (IMAP): A New NASA Mission

“…This interaction produces secondary electrons (red trajectories) that are guided to the outer annulus of the Start MCP. The mostly neutralized ions (black trajectories) traverse a 9.7 cm flight path and strike one of 24 Avalanche Photodiodes (APDs; Ogasawara et al 2016) where they generate secondary electrons that are guided to the center of the Stop MCP (purple trajectories). The TOF between the Start and Stop MCP signals yields the ion velocity.…”