Development of a Superconducting Analog-to-Digital Converter as a Readout for High-Resolution X-Ray Detectors Based on a Superconducting Tunnel Junction

Takayuki OKU  Tokihiro IKEDA  Chiko OTANI  Kazuhiko KAWAI  Hiromi SATO  Hirohiko M. SHIMIZU  Hiromasa MIYASAKA  Yoshiyuki TAKIZAWA  Hiroshi WATANABE  Wataru OOTANI  Hiroshi AKOH  Hiroshi NAKAGAWA  Masahiro AOYAGI  Tohru TAINO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E85-C   No.3   pp.645-649
Publication Date: 2002/03/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Superconductive Electronics)
Category: Digital Devices and Their Applications
Keyword: 
superconducting analog-to-digital converter,  X-ray detector,  readout,  SQUID,  SFQ,  

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Summary: 
We are developing a superconducting analog-to-digital converter (ADC) as a readout for high-resolution X-ray detectors based on a superconducting tunnel junction (STJ). The ADC has a sensitive front end which consists of a DC superconducting quantum interference device (SQUID). A signal current is digitized by this front end without using any preamplifiers. A single-flux-quantum (SFQ) pulse train whose frequency is proportional to the input current is launched by the front end, and integrated by a digital counter. The counter has a 10-bit resolution, and the integrated value is scanned and transferred to room-temperature processing modules with a frequency of 40 MHz. In this paper, the design of the ADC is described, and the preliminary results of the ADC performance test are shown. The performance of the STJ accompanied by the ADC is discussed in terms of the X-ray energy resolution.