Hafnium Films and Magnetic Shielding for TIME, A mm-Wavelength Spectrometer Array

J. Hunacek, J. Bock, C. M. Bradford, V. Butler, T. C. Chang, Y. T. Cheng, A. Cooray, A. Crites, C. Frez, S. Hailey-Dunsheath, B. Hoscheit, D. W. Kim, C. T. Li, D. Marrone, L. Moncelsi, E. Shirokoff, B. Steinbach, G. Sun, I. Trumper, A. TurnerB. Uzgil, A. Weber, M. Zemcov

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

TIME is a mm-wavelength grating spectrometer array that will map fluctuations of the 157.7-μ m emission line of singly ionized carbon ([CII]) during the epoch of reionization (redshift z∼ 5–9). Sixty transition-edge sensor (TES) bolometers populate the output arc of each of the 32 spectrometers, for a total of 1920 detectors. Each bolometer consists of gold absorber on a ∼ 3 × 3 mm silicon nitride micro-mesh suspended near the corners by 1 × 1 × 500 μ m silicon nitride legs targeting a photon-noise-dominated NEP ∼1×10-17W/Hz. Hafnium films are explored as a lower-Tc alternative to Ti (500 mK) for TIME TESs, allowing thicker support legs for improved yield. Hf Tc is shown to vary between 250 and 450 mK when varying the resident Ar pressure during deposition. Magnetic shielding designs and simulations are presented for the TIME first-stage SQUIDs. Total axial field suppression is predicted to be 5 × 10 7.

Original languageEnglish (US)
Pages (from-to)893-900
Number of pages8
JournalJournal of Low Temperature Physics
Volume193
Issue number5-6
DOIs
StatePublished - Dec 1 2018

Keywords

  • Bolometers
  • Hafnium
  • Magnetic shielding
  • Spectrometers
  • Transition-edge sensors

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

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