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Linearity Analysis and Efficiency Testing of The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) Science Cameras for FlightTo unveil the complexity of the solar atmosphere, measurement of the magnetic field in the upper chromosphere and transition region is fundamentally important, as this is where the forces transition from plasma to magnetic field dominated. Measurements of the field are also needed to elucidate the energy transport from the lower atmospheric regions to the corona beyond. Such an advance in heliospheric knowledge became possible with the first flight of the international solar sounding rocket mission, CLASP. For the first time, linear polarization was measured in Hydrogen Lyman-Alpha at 121.60 nm in September 2015. For linear polarization measurements in this emission line, high sensitivity is required due to the relatively weak polarization signal compared to the intensity. To achieve this high sensitivity, a low-noise sensor is required with good knowledge of its characterization, including linearity. This work presents further refinement of the linearity characterization of the cameras flown in 2015. We compared the current from a photodiode in the light path to the digital response of the detectors. Pre-flight CCD linearity measurements were taken for all three flight cameras and calculations of the linear fits and residuals were performed. However, the previous calculations included a smearing pattern and a digital saturation region on the detectors which were not properly taken into account. The calculations have been adjusted and were repeated for manually chosen sub-regions on the detectors that were found not to be affected. We present a brief overview of the instrument, the calibration data and procedures, and a comparison of the old and new linearity results. The CLASP cameras will be reused for the successor mission, CLASP2, which will measure the Magnesium II h & k emission lines between 279.45 nm and 280.35 nm. The new approach will help to better prepare for and to improve the camera characterization for CLASP2.
Document ID
20180001611
Acquisition Source
Marshall Space Flight Center
Document Type
Presentation
Authors
Walker, Salma C.
(California State Univ. Northridge, CA, United States)
Rachmeler, Laurel
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Winebarger, Amy
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Champey, Patrick
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Bethge, Christian
(Universities Space Research Association Huntsville, AL, United States)
Date Acquired
March 5, 2018
Publication Date
March 1, 2018
Subject Category
Solar Physics
Report/Patent Number
MSFC-E-DAA-TN52074
MSFC-E-DAA-TN52828
Meeting Information
Meeting: Annual Student Research and Creative Works Symposium
Location: Northridge, CA
Country: United States
Start Date: April 6, 2018
Sponsors: California State Univ.
Funding Number(s)
CONTRACT_GRANT: NSF AGS-1460767
CONTRACT_GRANT: 80MSFC17M0022
Distribution Limits
Public
Copyright
Portions of document may include copyright protected material.
Keywords
detector
CCD
linearit
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