Edward Wassell, Joseph Adams, Simon Bandler, James Chervenak, Renata Cumbee, Fred Finkbeiner, Joshua Fuhrman, Samuel Hull, Richard Kelley, Caroline Kilbourne, Jennette Mateo, Haruka Muramatsu, Frederick Porter, Asha Rani, Kazuhiro Sakai, Stephen Smith, Nicholas Wakeham, Sang Yoon
{"title":"Microcalorimeter Absorber Optimization for ATHENA and LEM","authors":"Edward Wassell, Joseph Adams, Simon Bandler, James Chervenak, Renata Cumbee, Fred Finkbeiner, Joshua Fuhrman, Samuel Hull, Richard Kelley, Caroline Kilbourne, Jennette Mateo, Haruka Muramatsu, Frederick Porter, Asha Rani, Kazuhiro Sakai, Stephen Smith, Nicholas Wakeham, Sang Yoon","doi":"10.1007/s10909-024-03173-3","DOIUrl":null,"url":null,"abstract":"<div><p>High quantum efficiency (QE) X-ray absorbers are needed for future X-ray astrophysics telescopes. The Advanced Telescope for High ENergy Astrophysics (ATHENA) mission requirements for the X-ray Integral Field Unit (X-IFU) instrument dictate, at their most stringent, that the absorber achieve vertical QE > 90.6% at 7 keV and low total heat capacity, 0.731 pJ/K. The absorber we have designed is 313 µm square composed of 1.05 μm Au and 5.51 μm electroplated Bi films (Barret et al. in Exp Astron 55:373–426, 2023). Overhanging the TES, the absorber is mechanically supported by 6 small legs whose 5 μm diameter is tuned to the target thermal conductance for the device. Further requirements for the absorber for X-IFU include a > 40% reflectance at wavelengths from 1 to 20 μm to reduce shot noise from infrared radiation from higher temperature stages in the cryostat. We meet this requirement by capping our absorbers with an evaporated Ti/Au thin film. Additionally, narrow gaps between absorbers are required for high fill fraction, as well as low levels of fine particulate remaining on the substrate and zero shorts between absorbers that may cause thermal crosstalk. The Light Element Mapper (LEM) is an X-ray probe concept optimized to explore the soft X-ray emission from 0.2 to 2.0 keV. These pixels for LEM require high residual resistance ratio (RRR) thin 0.5 µm Au absorbers to thermalize uniformly and narrow < 2 μm gaps between pixels for high areal fill fraction. This paper reports upon technology developments required to successfully yield arrays of pixels for both mission concepts and presents first testing results of devices with these new absorber recipes.</p></div>","PeriodicalId":641,"journal":{"name":"Journal of Low Temperature Physics","volume":"216 Part 3","pages":"417 - 426"},"PeriodicalIF":1.1000,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10909-024-03173-3.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Low Temperature Physics","FirstCategoryId":"101","ListUrlMain":"https://link.springer.com/article/10.1007/s10909-024-03173-3","RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"PHYSICS, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
High quantum efficiency (QE) X-ray absorbers are needed for future X-ray astrophysics telescopes. The Advanced Telescope for High ENergy Astrophysics (ATHENA) mission requirements for the X-ray Integral Field Unit (X-IFU) instrument dictate, at their most stringent, that the absorber achieve vertical QE > 90.6% at 7 keV and low total heat capacity, 0.731 pJ/K. The absorber we have designed is 313 µm square composed of 1.05 μm Au and 5.51 μm electroplated Bi films (Barret et al. in Exp Astron 55:373–426, 2023). Overhanging the TES, the absorber is mechanically supported by 6 small legs whose 5 μm diameter is tuned to the target thermal conductance for the device. Further requirements for the absorber for X-IFU include a > 40% reflectance at wavelengths from 1 to 20 μm to reduce shot noise from infrared radiation from higher temperature stages in the cryostat. We meet this requirement by capping our absorbers with an evaporated Ti/Au thin film. Additionally, narrow gaps between absorbers are required for high fill fraction, as well as low levels of fine particulate remaining on the substrate and zero shorts between absorbers that may cause thermal crosstalk. The Light Element Mapper (LEM) is an X-ray probe concept optimized to explore the soft X-ray emission from 0.2 to 2.0 keV. These pixels for LEM require high residual resistance ratio (RRR) thin 0.5 µm Au absorbers to thermalize uniformly and narrow < 2 μm gaps between pixels for high areal fill fraction. This paper reports upon technology developments required to successfully yield arrays of pixels for both mission concepts and presents first testing results of devices with these new absorber recipes.
期刊介绍:
The Journal of Low Temperature Physics publishes original papers and review articles on all areas of low temperature physics and cryogenics, including theoretical and experimental contributions. Subject areas include: Quantum solids, liquids and gases; Superfluidity; Superconductivity; Condensed matter physics; Experimental techniques; The Journal encourages the submission of Rapid Communications and Special Issues.