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

Hunacek, Jonathon; Bock, J. J.; Bradford, C. M.; Butler, V.; Chang, Tzu-Ching; Cheng, Yun-Ting; Cooray, Asantha; Crites, A. T.; Frez, Clifford; Hailey-Dunsheath, S.; Hoscheit, Benjamin L.; Kim, D. W.; Li, Chao-Te; Marrone, Dan; Shirokoff, E.; Steinbach, B.; Sun, Guochao; Trumper, Isaac; Turner, Anthony; Uzgil, Bade; Weber, A. C.; Zemcov, Michael

doi:10.1007/s10909-018-1906-3

Cited by 9 publications

(12 citation statements)

References 10 publications

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“…We note that the TIME spectrometer covers the full 183 GHz to 326 GHz band, while only the 201 GHz to 302 GHz subband is used for science. The other channels at the highand low-frequency edges (a total of 16) serve as atmospheric monitors (Hunacek et al 2016). Because they access the water lines, they combine to provide greater sensitivity to the precipitable water-vapor (PWV) fluctuations than the combined science band channels, allowing effective tracking removal of the water vapor fluctuations to below the instrumental noise levels.…”

Section: Continuum Emissionmentioning

confidence: 99%

“…TIME is a wide-bandwidth, imaging spectrometer array (Crites et al 2014;Hunacek et al 2016Hunacek et al , 2018 designed for simultaneously (1) conducting the first tomographic measurement of [C II] intensity fluctuations during the EoR, and (2) investigating the molecular gas growth at cosmic noon by measuring the intensity fluctuations of rotational CO lines, which also present a source of foreground contamination (Lidz & Taylor 2016;Cheng et al 2016;Sun et al 2018;Cheng et al 2020). TIME will operate at the ALMA 12-m Prototype Antenna (APA) at the Arizona Radio Observatory (ARO) in Kitt Peak, Arizona, for 1000 hours of winter observing time, starting in 2021.…”

Section: Introductionmentioning

confidence: 99%

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Probing Cosmic Reionization and Molecular Gas Growth with TIME

Sun

Chang

Uzgil

et al. 2021

ApJ

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Line intensity mapping (LIM) provides a unique and powerful means to probe cosmic structures by measuring the aggregate line emission from all galaxies across redshift. The method is complementary to conventional galaxy redshift surveys that are object-based and demand exquisite point-source sensitivity. The Tomographic Ionized-carbon Mapping Experiment (TIME) will measure the star formation rate (SFR) during cosmic reionization by observing the redshifted [C II] 158 µm line (6 z 9) in the LIM regime. TIME will simultaneously study the abundance of molecular gas during the era of peak star formation by observing the rotational CO lines emitted by galaxies at 0.5 z 2. We present the modeling framework that predicts the constraining power of TIME on a number of observables, including the line luminosity function, and the auto-and cross-correlation power spectra, including synergies with external galaxy tracers. Based on an optimized survey strategy and fiducial model parameters informed by existing observations, we forecast constraints on physical quantities relevant to reionization and galaxy evolution, such as the escape fraction of ionizing photons during reionization, the faint-end slope of the galaxy luminosity function at high redshift, and the cosmic molecular gas density at cosmic noon. We discuss how these constraints can advance our understanding of cosmological galaxy evolution at the two distinct cosmic epochs for TIME, starting in 2021, and how they could be improved in future phases of the experiment.

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Section: Continuum Emissionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probing Cosmic Reionization and Molecular Gas Growth with TIME

Sun

Chang

Uzgil

et al. 2021

ApJ

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“…Its superconducting properties have been thoroughly investigated for use in superconducting tunnel junction detectors [14][15][16] and transition edge sensors. 17,18 Sputtered films have a hexagonal close-packed (hcp) crystal structure and are in the local superconducting limit with critical temperatures ranging from 140 to 450 mK depending on deposition conditions. Furthermore, the surface impedance and quasiparticle lifetime of Hf films are similar to those in PtSi x and TiN x devices which mean that very little optimization needs to be done to transition detector array designs to this material.…”

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confidence: 99%

Design and performance of hafnium optical and near-IR kinetic inductance detectors

Zobrist

Coiffard

Bumble

et al. 2019

Applied Physics Letters

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We report on the design and performance of Microwave Kinetic Inductance Detectors (MKIDs) sensitive to single photons in the optical to near-infrared range using hafnium as the sensor material. Our test device had a superconducting transition temperature of 395 mK and a room temperature normal state resistivity of 97 µΩ cm with an RRR = 1.6. Resonators on the device displayed internal quality factors of around 200 000. Similar to the analysis of MKIDs made from other highly resistive superconductors, we find that modeling the temperature response of the detector requires an extra broadening parameter in the superconducting density of states. Finally, we show that this material and design is compatible with a full-array fabrication process which resulted in pixels with decay times of about 40 µs and resolving powers of ∼9 at 800 nm.Optical and near-IR (OIR) MKIDs are superconducting sensors capable of measuring the arrival time and energy of optical to near-infrared photons. 1 They are less sensitive to false counts and radiation damage 2 than semiconductor devices operating in the same wavelength range and can achieve higher readout speeds. Moreover, each MKID is a high quality factor resonator which allows for natural frequency domain multiplexing and distinguishes the technology from other superconducting detectors. These advantages make arrays of OIR MKIDs useful as astrophysics cameras focusing on timedomain astronomy 3-5 and high contrast imaging. 6-8 To date, commissioned instruments have used either nonstoichiometric titanium nitride or platinum silicide alloys as the photon-sensitive material in the resonators and have achieved resolving powers, R = E/∆E, of up to 8 at 800 nm. 9 This resolving power has been shown to be limited equally by stationary noise, generated by two-level systems (TLS) in the device and amplifiers in the readout chain, as well as an intrinsic variance in the photon signal pulse height, likely caused by phonon escape from the superconductor to the substrate during the initial photon energy down-conversion. 10

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“…Here, we investigate hafnium as a potential candidate for this application. Its su perconducting properties have been probed for use in superconducting tunnel junction detectors [71,130,131] and transition edge sensors [132,133]. Sputtered films have a hexagonal closepacked crystal structure and are in the local superconducting limit with critical temperatures ranging from 140 to 450 mK depending on deposition conditions.…”

Section: Hafniummentioning

confidence: 99%

Improving the Resolving Power of Ultraviolet to Near-Infrared Microwave Kinetic Inductance Detectors

Zobrist¹

2022

Springer Theses

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dark matter searches to biological imaging and astronomy. The performance of these de tectors often limits the achievable science goals for an application, so improvements to detector technologies can be transformative. This dissertation focuses on these detector enhancements, emphasizing the requirements for one particular application, exoplanet di rect imaging. However, the work done here remains broadly applicable to fields needing highly sensitive sensors in this wavelength range.Finding and studying the properties of exoplanets orbiting distant stars can tell us much about solar system dynamics and the formation of our own solar system. With sufficiently precise measurements we might also discover the presence of water or even biological processes on these planets. To achieve this goal, we need astronomical instrumentation ca pable of separating an exoplanet's light from its host star by directly imaging it. For many exoplanets, though, we receive at our telescope only roughly one photon for every billion from the star. Even worse, these two light sources often partially overlap because of the relative closeness of exoplanets to their stars and the diffraction limit set by the finite size xi of our telescope optics. Therefore, the extreme contrast ratio between the brightness of the star and planet sets the performance requirements for this kind of instrument.Carrying out this measurement with the traditional semiconductor based sensors can be difficult. They detect the intensity of light at each pixel and introduce excess noise into the system. However, superconducting sensors avoid this limitation because of their ex tra sensitivity. Each individual incident photon can be resolved making them essentially perfect photon counting detectors, which enables the detection of exoplanets with more challenging contrast ratios than detectable with conventional detectors. The system noise in a superconducting sensor, instead, determines how accurately the photon energy can be measured through the size of the detector response. Because of this extra energy measure ment capability these detectors do not need the complicated optical systems typically used to measure an exoplanet's atmospheric spectrum. The accuracy at which we can resolve these planetary spectra determines how much we can learn about a planet and, as such, is the principal metric for the performance of these devices.The Microwave Kinetic Inductance Detector (MKID) is unique among other supercon ducting technologies because it allows for the simple readout of tens to hundreds of thou sands of pixels, which is a requirement for when the exact location of an exoplanet is un known. This dissertation focuses on improving the spectral resolving power of MKIDs to make them the superior option for ultraviolet to nearinfrared measurements and, in partic ular, for exoplanet direct imaging. Chapters 1 and 2 discuss the significance of MKIDs as astronomical detectors and the relevant physics needed to understand their operation. In the following chapters, four sepa...

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

Cited by 9 publications

References 10 publications

Probing Cosmic Reionization and Molecular Gas Growth with TIME

Probing Cosmic Reionization and Molecular Gas Growth with TIME

Design and performance of hafnium optical and near-IR kinetic inductance detectors

Improving the Resolving Power of Ultraviolet to Near-Infrared Microwave Kinetic Inductance Detectors

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