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Title: On determination of charge transfer efficiency of thick, fully depleted CCDs with 55 Fe x-rays

Abstract

Charge transfer efficiency (CTE) is one of the most important CCD characteristics. Our paper examines ways to optimize the algorithms used to analyze 55Fe x-ray data on the CCDs, as well as explores new types of observables for CTE determination that can be used for testing LSST CCDs. Furthermore, the observables are modeled employing simple Monte Carlo simulations to determine how the charge diffusion in thick, fully depleted silicon affects the measurement. The data is compared to the simulations for one of the observables, integral flux of the x-ray hit.

Authors:
 [1];  [2];  [2]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States); Pacific Univ., Forest Grove, OR (United States)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1392232
Report Number(s):
BNL-114245-2017-JA
Journal ID: ISSN 1748-0221
Grant/Contract Number:
SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Instrumentation
Additional Journal Information:
Journal Volume: 12; Journal Issue: 07; Conference: Precision Astronomy with Fully Depleted CCDs, Upton, NY (United States), 01-02 Dec 2016; Journal ID: ISSN 1748-0221
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; charge transport and multiplication in solid media; detector modelling and simulations II; photon detectors for UV; visible and IR photons; image processing

Citation Formats

Yates, D., Kotov, I., and Nomerotski, A. On determination of charge transfer efficiency of thick, fully depleted CCDs with 55 Fe x-rays. United States: N. p., 2017. Web. doi:10.1088/1748-0221/12/07/C07025.
Yates, D., Kotov, I., & Nomerotski, A. On determination of charge transfer efficiency of thick, fully depleted CCDs with 55 Fe x-rays. United States. doi:10.1088/1748-0221/12/07/C07025.
Yates, D., Kotov, I., and Nomerotski, A. Sat . "On determination of charge transfer efficiency of thick, fully depleted CCDs with 55 Fe x-rays". United States. doi:10.1088/1748-0221/12/07/C07025.
@article{osti_1392232,
title = {On determination of charge transfer efficiency of thick, fully depleted CCDs with 55 Fe x-rays},
author = {Yates, D. and Kotov, I. and Nomerotski, A.},
abstractNote = {Charge transfer efficiency (CTE) is one of the most important CCD characteristics. Our paper examines ways to optimize the algorithms used to analyze 55Fe x-ray data on the CCDs, as well as explores new types of observables for CTE determination that can be used for testing LSST CCDs. Furthermore, the observables are modeled employing simple Monte Carlo simulations to determine how the charge diffusion in thick, fully depleted silicon affects the measurement. The data is compared to the simulations for one of the observables, integral flux of the x-ray hit.},
doi = {10.1088/1748-0221/12/07/C07025},
journal = {Journal of Instrumentation},
number = 07,
volume = 12,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on July 1, 2018
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  • Lateral charge diffusion in back-illuminated CCDs directly affects the point spread function (PSF) and spatial resolution of an imaging device. This can be of particular concern in thick, back-illuminated CCDs. We describe a technique of measuring this diffusion and present PSF measurements for an 800 x 1100, 15 mu m pixel, 280 mu m thick, back-illuminated, p-channel CCD that can be over-depleted. The PSF is measured over a wavelength range of 450 nm to 650 nm and at substrate bias voltages between 6 V and 80 V.
  • We present a new method to measure charge diffusion in charge-coupled devices (CCDs). The method is based on a statistical characterization of the shapes of charge clouds produced by low-energy X-rays using known properties of the two-dimensional Gaussian point-spread function (PSF). The algorithm produces reliable upper and lower bounds on the size of the PSF for photons converting near the entrance window of a device. It is optimally suited to the case of thick back-illuminated CCDs where the X-ray absorption length is smaller than the silicon thickness and the diffusion scale is of the same order as the pixel size.more » The only assumptions are that the charge cloud width is a monotonically increasing function of distance from the conversion point to the buried channel, and that the conversion probability is peaked at the surface. Otherwise, no physical models of carrier transport or knowledge of the electric field profile in the CCD are needed. In suboptimal conditions, the upper bound increases and the lower bound is unaffected, so confidence in the correctness of results is retained. The new method has been benchmarked against Monte Carlo simulations and tested on X-ray images measured on thick high-resistivity prototype CCDs for the Large Synoptic Survey Telescope. In Monte Carlo simulations of noiseless images having the optimal diffusion scale, the upper bound approximated the true PSF within 5%, increasing to 10% in simulations with added noise. Even with severely undersampled or truncated PSFs, the method brackets the true value to within 25%. Our method is accurate and computationally efficient and offers a fast and simple experimental setup.« less
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