Improving the Thermal Stability of a CCD Through Clocking

TL;DR

This paper presents a novel clocking technique called 'dither clocking' that significantly reduces temperature variations in CCD detectors, thereby improving the stability of high-precision spectrometers used for exoplanet detection.

Contribution

The paper introduces and evaluates a new charge shuffling method during CCD readout to minimize temperature fluctuations in the detector.

Findings

Dither clocking reduces CCD temperature variations substantially.

The technique does not adversely affect spectral data quality.

Improved detector stability enhances radial velocity measurement precision.

Abstract

Modern precise radial velocity spectrometers are designed to infer the existence of planets orbiting other stars by measuring few-nm shifts in the positions of stellar spectral lines recorded at high spectral resolution on a large-area digital detector. While the spectrometer may be highly stabilized in terms of temperature, the detector itself may undergo changes in temperature during readout that are an order of magnitude or more larger than the other opto-mechanical components within the instrument. These variations in detector temperature can translate directly into systematic measurement errors. We explore a technique for reducing the amplitude of CCD temperature variations by shuffling charge within a pixel in the parallel direction during integration. We find that this "dither clocking" mode greatly reduces temperature variations in the CCDs being tested for the NEID spectrometer. We investigate several potential negative effects this clocking scheme could have on the underlying spectral data.