Measurements of Charge Transfer Inefficiency in a CCD With High-Speed Column Parallel Readout

Abstract

Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying short-lived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. A test stand for measuring the charge transfer inefficiency (CTI) of a prototype CPCCD has been set up. Studies of the CTI have been performed at a range of readout frequencies and operating temperatures. Abstract-Charge Coupled Devices (CCDs) have been successfully used in several high energy physics experiments over the past two decades. Their high spatial resolution and thin sensitive layers make them an excellent tool for studying shortlived particles. The Linear Collider Flavour Identification (LCFI) collaboration is developing Column-Parallel CCDs (CPCCDs) for the vertex detector of a future Linear Collider. The CPCCDs can be read out many times faster than standard CCDs, significantly increasing their operating speed. A test stand for measuring the charge transfer inefficiency (CTI) of a prototype CPCCD has been set up. Studies of the CTI have been performed at a range of readout frequencies and operating temperatures.

Comparison of Measurements of Charge Transfer Inefficiencies in a CCD with High-Speed Column Parallel Readout

“…A clear X-ray signal is extracted by calculating the difference between the noise centroid (baseline) and the X-ray centroid after well determining them. The statistical uncertainties have been reduced compared to a previous work with CPC-1 [17]. The reduced uncertainties are due to the improved method, as we do not expect a different behavior between CPC-1 and CPC-T regarding the CTI measurements as both devices have a very similar geometric structure.…”

“…The CTI has been calculated using a linear fit of average ADC codes versus pixel number. Figure 8 shows a comparison with the CPC-1 measurement [17] taken at the test stand in Liverpool. Uncertainties have been reduced mostly by increasing the number of frames.…”

“…The CPC-T used is a 4-phase variant of the CPCCD technology capable of 50 MHz readout frequency. Experimental work at Liverpool University on an un-irradiated CPC-1 led to CTI values compatible with zero but with rather large uncertainties [17]. In this paper we demonstrate a method to determine the CTI value with an un-irradiated CPC-T aiming for small CTI uncertainties.…”

“…Simulation and modeling of CCD radiation hardness effects for a CCD prototype with sequential readout was reported at IEEE2005; comparing full TCAD simulations with analytic models was reported at IEEE2006; simulation and modeling of a CCD prototype with column parallel readout (CPCCD) was reported at IEEE2007 and in [14]. Experimental measurements using a method to determine the charge transfer inefficiency (CTI) were performed with a CPCCD prototype CPC-1 at a test stand at Liverpool University [17]. This work focuses on a new CPCCD prototype, CPC-T, at a test stand at Oxford University.…”

“…Fig.8.Comparison of the Oxford results with 10000 frames with the Liverpool results[17] where the number of frames was 5000 and a fraction of data was lost because of a sampling inefficiency.…”