Performance of the Charge-Injection Capability of Suzaku XIS

Abstract

A charge-injection technique is applied to the X-ray CCD camera, XIS (X-ray Imaging Spectrometer) aboard Suzaku. The charge transfer inefficiency (CTI) in each CCD column (vertical transfer channel) is measured by the injection of charge packets into a transfer channel and subsequent readout. This paper reports on the performances of the charge-injection capability based on the ground experiments using a radiation-damaged device, and in-orbit measurements of the XIS. The ground experiments show that charges are stably injected with a dispersion of 91eV in FWHM in a specific column for the charges equivalent to an X-ray energy of 5.1keV. This dispersion width is significantly smaller than that of the X-ray events of 113eV (FWHM) at approximately the same energy. The amount of charge loss during transfer in a specific column, which is measured with the charge-injection capability, is consistent with that measured with the calibration source. These results indicate that the charge-injection technique can accurately measure column-dependent charge losses, rather than the calibration sources. The column-to-column CTI correction to the calibration source spectra significantly reduces the line widths compared to those with a column-averaged CTI correction (from 193eV to 173eV in FWHM on an average at the time of one year after the launch). In addition, this method significantly reduces the low-energy tail in the line profile of the calibration source spectrum.

The Gamma-Ray Origin of RX J0852.0-4622 Quantifying the Hadronic and Leptonic Components: Further Evidence for the Cosmic-Ray Acceleration in Young Shell-type SNRs

“…In the present work, we only used the data obtained with XIS0 (excluding segment A after 2009 June 23), XIS1, and XIS3. These observations utilized spaced row charge injection (SCI; Nakajima et al 2008;Uchiyama et al 2009) except for observation ID 500010010. In the present analysis, we used cleaned event files processed and screened by HEASoft version 6.11 7 and Suzaku pipeline versions 2.0, 2.2, and 2.8.…”

Long‐Term Density Trend in the Mesosphere and Lower Thermosphere From Occultations of the Crab Nebula With X‐Ray Astronomy Satellites

“…Here, we make use of them to reveal long‐term trends of the air density. Specifically, we use data acquired with the X‐ray astronomy satellites/instruments, ASCA/GIS (Ohashi et al., 1996; Tanaka et al., 1994), RXTE/PCA (Jahoda et al., 1996), Suzaku/XIS + PIN (Koyama et al., 2007; Mitsuda et al., 2007; Takahashi et al., 2007), NuSTAR/FPM (Harrison et al., 2013), and Hitomi/HXI (Nakazawa et al., 2018; Takahashi et al., 2018). Capabilities of individual instruments are summarized in Table 1.…”

Experimental studies on the charge transfer inefficiency of CCD developed for the soft X-ray imaging telescope Xtend aboard the XRISM satellite

“…Therefore, the charge transfer inefficiency (CTI), the fraction of charge loss per transfer, is an important measure in evaluating CCDs. In addition to trap populations and densities, the CTI generally depends on several operation parameters: transfer time [3], operating temperature [4,5,6], amount of transfer charge [7,8,9], and the existence of "sacrificial charge" [10,11,12,13,14,15]. In the case of a photoncounting X-ray CCD, which serves as a spectrometer as well as an imager, the charge loss during transfer results in misidentification of an incident photon energy.…”