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FIREBall-2 during pre-flight sky tests at the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico Image courtesy P. Balard. Inset shows the experiment in flight alongside a full Moon. This is a real, non-photoshopped image of FIREBall-2 hanging from the balloon with the moon in the background. Image by Mouser Williams, Los Alamos, NM, September 22, 2018.
Above: FIREBall-2 during pre-flight sky tests at the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico Image courtesy P. Balard. Inset shows the experiment in flight alongside a full Moon. This is a real, non-photoshopped image of FIREBall-2 hanging from the balloon with the moon in the background. Image by Mouser Williams, Los Alamos, NM, September 22, 2018.

Suborbital

Photon-Counting Ultraviolet Detector for FIREBALL

For the past three decades, theoretical physicists have predicted that primordial gas from the Big Bang is not spread uniformly throughout space but is instead distributed as a “cosmic web,” or a network of smaller and larger filaments crisscrossing one another across the vastness of space, called the intergalactic medium (IGM) by astronomers. This cosmic web is the source of gas that fuels the birth and growth of galaxies. The energy released by the IGM is extremely faint and can therefore only be measured by highly sensitive instruments like the one used in the Faint Intergalactic Redshifted Emission Balloon (FIREBall) experiment. FIREBall is designed to measure IGM emission that has been redshifted (z~0.7) through time and space to an ultraviolet (UV) wavelength range that is accessible at stratospheric balloon altitudes. The FIREBall 2 mission is a team of collaborating institutes in the US (Caltech, JPL, Columbia University) and France (CNES, LAM). Two missions preceded FIREBall 2; Galaxy Evolution Explorer (GALEX) and FIREBall 1. FIREBall 1, while a technical and engineering success, used a spare microchannel plate detector from GALEX that elucidated the need for lower detection limits. Improvements to FIREBall 2 were made possible, in part, by the incorporation of a high-performance silicon detector developed at the Microdevices Laboratory (MDL).

FIREBall 2, a balloon-borne UV spectrograph jointly funded by NASA and France’s National Centre for Space Studies, is designed to observe emission from the IGM and the circumgalactic medium, the diffuse gas around galaxies. These emissions carry signatures of galactic feedback, including matter and energy outflows. Understanding the morphology, thermodynamics, chemistry, and kinematics of this gas is key to understanding galaxy formation and evolution. The FIREBall-2 instrument is optimized for narrowband observations spanning the stratospheric window centered at 205 nanometers. These measurements are complementary to those made by Caltech’s Cosmic Web Imager, which examines IGM emission at a larger redshift.

Using MDL technologies, JPL delivered a high performance, UV, photon counting detector by optimizing the response of an electron multiplying charge-coupled device (EMCCD) to the observation window of FIREball 2. The EMCCD is a powerful imaging architecture with photon counting capability. When combined with JPL’s 2D-doping and custom antireflection (AR) coatings, the result is a mission-enabling UV detector with unprecedented quantum efficiency and noise characteristics (QE of > 55% for our bandpass of 200-213 nm, read noise << 1 electron). A CCD controller for counting photons (CCCP) created by Nüvü (Montreal) is used to clock these devices and readout images. FIREBall-2 was launched on September 22nd , 2018 from Fort Sumner, New Mexico. The team demonstrated a successful launch and operation of the spectrograph and was only the second time an EMCCD has been used for a space-like mission!

The FIREBall mission’s principal investigator is Christopher Martin, professor of physics at Caltech. Principal investigator for the Photon-counting Ultraviolet Detector is Shouleh Nikzad at MDL.
Flight Ready, FIREBall 2 in the hanger at the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. Image courtesy P. Balard. Scientific Balloon. Scientific Balloon Flight Facility in Fort Sumner, N.M. Image courtesy HySICS Team/LASP Two packaged been 2D doped and AR coated EMCCDs (e2v) that have for the FIREBall experiment. The different colors (dark purple and light blue) result from differences in the AR coating design.
Flight Ready, FIREBall 2 in the hanger at the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. Image courtesy P. Balard. Scientific Balloon. Scientific Balloon Flight Facility in Fort Sumner, N.M. Image courtesy HySICS Team/LASP Two packaged been 2D doped and AR coated EMCCDs (e2v) that have for the FIREBall experiment. The different colors (dark purple and light blue) result from differences in the AR coating design.
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High Efficiency Far UV Photon Counting Detector with Out of band (visible) Rejection for SHIELDS

SHIELDS (Spatial Heterodyne Interferometric Emission Line Diagnostic Spectrometer) is a technology demonstration for the study of heliosphere, solar, and corona. Information from non-thermal processes such as photochemical energy and plasma wave propagation, and signatures of solar-driven auroral and ionospheric processes such as Joule heating and exospheric escape allows better understanding in Sun-planet interactions. These energetic process in the sun, heliosphere, and planetary environments can be characterized by studying emissions lines. Most important spectral features are found in the solar continuum-free extreme ultraviolet (EUV) to far ultraviolet (FUV) range, which makes spectral resolving power very significant to this study.

SHIELDS is planning a secondary payload: a compact instrument with high emission-line spectroscopy resolving power using JPL’s 2D-doped EMCCD camera and the University of Arizona's Reflective Spatial Heterodyne Spectrometer (RSHS) self-scanning interferometer. The 2D-doped EMCCD has a custom metal dielectric filter directly deposited on the surface which provides better than 3 orders of magnitude out of band rejection optimized at 121 nm. Custom, compact 3-board electronics designed and fabricated at JPL completes the camera to be delivered by JPL. A vacuum enclosure was developed at University of Arizona to house the JPL 2D-doped EMCCD and camera electronics. The enclosure footprint is a scant six inches by six inches with the required cooling provided by a 0.75 watt cryocooler that is attached directly to the EMCCD. A single board computer is used to communicate, and transfer data from the camera electronics.

Principal investigator for SHIELDS is Professor Walter Harris at University of Arizona. Principal investigator for the SHIELDS camera is Shouleh Nikzad at MDL, Sam Cheng is the lead for the detector characterization.
<strong>Left top:</strong> 2D-doped EMCCD with a directly applied metal dielectric filters. <br/><br/> <strong>Left bottom:</strong> SHIELDS camera assembly stack. Sounding rocket launching from Wallops Flight Facility. <br/><br/> <strong>Right:</strong> Sam Cheng is the lead of the detector characterization.
Left top: 2D-doped EMCCD with a directly applied metal dielectric filters.

Left bottom: SHIELDS camera assembly stack. Sounding rocket launching from Wallops Flight Facility.

Right: Sam Cheng is the lead of the detector characterization.
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Magnetosphere Ionosphere Coupling in the Alfvén Resonator Low-Energy Electron-Spectrometer

The Magnetosphere-Ionosphere Coupling in the Alfven Resonator (MICA) heliophysics sounding rocket mission incorporated a delta-doped array as the science detector in its Low Energy Electron Spectrometer (LEES). The objective of this experiment was to investigate the role of active ionospheric feedback in the development of large amplitude/small-scale electromagnetic waves and density depletions in the low altitude (<400 km), downward current, auroral ionosphere—a critical component in understanding magnetosphere-ionosphere coupling.

2D-doped detectors allow direct detection of low-energy electrons without the need for acceleration by high voltages allowing them to begin detection at lower altitudes than what is needed by conventional detectors (e.g., MCPs). For this application, we operated the imaging detector in “photodiode mode”, in which all of the output signal is added and read out as a current via a low noise circuit, digitized, and stored. MICA had a successful launch with a functional LEES instrument. The LEES experiment served the purpose of demonstrating the successful flight and operation of a 2D-doped particle detector.

Principal investigator for MICA-LEES was Steven Powell at Cornell University. Principal investigator for the low energy electron threshold is Shouleh Nikzad at MDL, Todd Jones was the lead for the hardware delivery.
MICA-LEES instrument and an early prototype delta-doped CCD with membrane stiffener to be integrated into LEES.
MICA-LEES instrument and an early prototype delta-doped CCD with membrane stiffener to be integrated into LEES.
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Colorado High-resolution Echelle Stellar Spectrograph

The Colorado High-resolution Echelle Stellar Spectrograph (CHESS) is a rocket-borne far-ultraviolet spectrograph that serves as a pathfinder instrument and technology testbed for high-resolution spectrographs for future NASA astrophysics missions (e.g., LUVOIR) The CHESS rocket experiment is designed to quantify the composition and physical state of the interstellar medium (ISM), specifically the interface regions between translucent clouds and the ambient diffuse ISM; quantifying the temperature, composition, and kinematics of nearby interstellar clouds. The local ISM provides an opportunity to study general ISM phenomena up close and in three dimensions, including interactions of different phases of the ISM, cloud collisions, cloud evolution, ionization structure, thermal balance, turbulent motions, etc. (see review by Redfield et al. 2006). The CHESS instrument is an objective echelle spectrograph operating at f/12.4 and resolving power of R≈120,000 over a bandpass of 100-160 nm. Preceding CHESS missions have flown in 2014 and 2016 using a cross-strip anode MCP detector.

CHESS in the future will incorporate an echelle grating fabricated using advanced electron-beam etching techniques developed at Pennsylvania State University, and the payload will be further reconfigured to replace the MCP detector with a 2D-doped, SNAP CCD—a 3508×3512 pixel, 10.5-µm square pixel format, high-resistivity, p-channel CCD designed by Lawrence Berkeley National Laboratory (LBNL). These devices are 200 mm thick, back-illuminated, and packaged in a PCB picture frame; because the CHESS spectral range extends to 100 nm, the detector has no AR coating.
Todd Jones at MDL processing detectors in preparation for 2D doping.
Todd Jones at MDL processing detectors in preparation for 2D doping.
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A 2D-doped, p-channel (LBNL-SNAP) CCD was delivered for a flight of CHESS.
A 2D-doped, p-channel (LBNL-SNAP) CCD was delivered for a flight of CHESS.
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