[1]Cody J. Duell

1]Department of Physics, Cornell University, Ithaca, NY, USA 2]Quantum Sensors
Division, NIST, Boulder, CO, USA 3]Department of Physics and Astronomy,
University of British Columbia, Vancouver,BC, Canada 4]Department of Physics
and Atmospheric Science, Dalhousie University, Halifax,NS, Canada 5]Department
of Astronomy, Cornell University, Ithaca,NY, USA 6]AWS Center for Quantum
Computing, Amazon, Pasadena, CA, USA 7]School of Earth and Space Exploration,
Arizona State University, Tempe, AZ, USA 8]Department of Physics and
Astronomy, University of Victoria, Victoria, BC, Canada 9]Cornell Center for
Astrophysics and Planetary Sciences, Cornell University, Ithaca, NY, USA
10]Department of Applied and Engineering Physics, Cornell University, Ithaca,
NY, USA

# CCAT: Comparisons of 280 GHz TiN and Al Kinetic Inductance Detector Arrays

<EMAIL_ADDRESS>Jason Austermann  James Beall  James R. Burgoyne  Scott C.
Chapman  Steve K. Choi  Rodrigo G. Freundt  Jiansong Gao  Christopher Groppi
Anthony I. Huber  Zachary B. Huber  Johannes Hubmayr  Ben Keller  Yaqiong Li
Lawrence T. Lin  Justin Matthewson  Philip Mauskopf  Alicia Middleton  Colin
C. Murphy  Michael D. Niemack  Thomas Nikola  Adrian K. Sinclair  Ema Smith
Jeff van Lanen  Anna Vaskuri  Eve M. Vavagiakis  Michael Vissers  Samantha
Walker  Jordan Wheeler  Bugao Zou  [  [  [  [  [  [  [  [  [  [

###### Abstract

The CCAT Collaboration’s six-meter Fred Young Submillimeter Telescope is
scheduled to begin observing in the Chilean Atacama in 2025, targeting a
variety of science goals throughout cosmic history. Prime-Cam is a 1.8-meter
diameter cryostat that will host up to seven independent instrument modules
designed for simultaneous spectroscopic and broadband, polarimetric surveys at
millimeter to submillimeter wavelengths. The first of these instrument
modules, the 280 GHz module, will include ${\sim}$10,000 kinetic inductance
detectors (KIDs) across three arrays. While the first array was fabricated out
of tri-layer TiN/Ti/TiN, the other two arrays were fabricated out of a single
layer of Al. This combination of materials within the same instrument provides
a unique opportunity to directly compare the performance and noise properties
of two different detector materials that are seeing increasing use within the
field. We present preliminary comparisons here based on lab testing, along
with a discussion of the potential impacts on operation when observing and
translating raw data to science-grade maps.

###### keywords:

kinetic inductance detectors, detector arrays, cosmic microwave background,
CCAT, FYST

##  1 Introduction

Superconducting detectors have become the state of the art for measuring faint
astronomical signals at millimeter and submillimeter wavelengths. Kinetic
inductance detectors (KIDs), a type of superconducting resonator [1], have
become an increasingly popular choice in recent years due to their sensitivity
and ease of multiplexing. KIDs allow for high detector counts and photon-
limited sensitivity, while also being simpler to read out than comparably-
sensitive transition edge sensors. At the same time, the technology is new
enough that there remain significant questions about their noise performance
and optimization for the field, one of the most basic of which is the choice
of material for the detector. For photon-limited operation of KIDs at
millimeter and submillimeter wavelengths, KIDs have typically been designed
for bath temperatures of 100–300 mK with an inductor transition temperature,
$T_{c}$, of 0.5–1.5 K [2, 3, 4, 5]. At the same time, the material must also
be robust to fabrication at wafer-scales and repeated cryogenic cycling.

Given these constraints, two of the most popular materials for KIDs in these
bands are Al and TiN, both of which have shown photon-limited noise
performance [6, 7] and have been fabricated at array scales. The primary
difference between these materials is that TiN is a “disordered”
superconductor, meaning that it has much higher resistivity above $T_{c}$ than
Al, which has several implications, including higher kinetic inductance per
square and easier impedance matching for photon absorption. Imaging
experiments that have fielded Al KIDs include NIKA [8], NIKA2 [3], OLIMPO [9],
and MUSCAT [10], while TiN detectors have seen use for MAKO [11], BLAST-TNG
[2], TolTEC [12], and, at slightly higher frequencies, ARCONS [13].

CCAT’s 280 GHz instrument module for Prime-Cam provides an opportunity to test
these two materials side-by-side in a near 1:1 setting. In this paper, we will
lay the groundwork for that comparison, as well as provide early discussion
based on lab testing. In Section 2, we will briefly describe Prime-Cam and the
280 GHz instrument module, as well as the relevant focal plane and detector
designs. In Section 3, we will make early comparisons in terms of noise
performance, sensitivity, and expected yield. We will conclude with a
discussion of future work.

Figure 1: Exploded views of the Al detector modules (left) with Si platelet
feedhorns and TiN detector module (right) with Al machined feedhorns. The
inset shows the focal plane layout for all three arrays.

##  2 Background

###  2.1 Prime-Cam and the Fred Young Submillimeter Telescope

The Fred Young Submillimeter Telescope (FYST) is being built in the Chilean
Atacama by the CCAT Collaboration at an elevation of 5600 meters near the
summit of Cerro Chajnantor [14]. It has a six-meter aperture with a modified
off-axis, crossed-Dragone design [15], which offers a wide field-of-view and
high throughput to take advantage of the exceptional atmospheric conditions.
FYST is scheduled to begin making observations in 2025. Prime-Cam will be one
of two primary instruments for FYST, targeting a variety of science goals
throughout cosmic history [16, 17]. Prime-Cam is a 1.8-m diameter cryostat
that will host up to seven independent instrument modules spanning 220–850
GHz, each with a ${\sim}1.3$ degree field-of-view, allowing for the completion
of simultaneous broadband and spectroscopic surveys [18].

###  2.2 280 GHz Instrument Module and Mod-Cam

The first of the Prime-Cam instrument modules, the 280 GHz module, will be
used for both wide-field and small-field surveys and is populated with three
independent, hexagonally-tiled detector arrays with a shared optical path. The
280 GHz instrument module will include ${\sim}10,000$ polarization-sensitive
KIDs across three arrays and will initially be deployed in Mod-Cam, a single
module testbed for telescope commissioning and development of future modules.
Details of Mod-Cam and the 280 GHz instrument module can be found in [19].

###  2.3 Focal Plane Module Designs

The first KID array was fabricated out of tri-layer TiN/Ti/TiN, while the
other two arrays were entirely out of Al. All three arrays were fabricated on
550-micron silicon-on-insulator wafers by the Quantum Sensors Group at the
National Institute for Standards and Technology (NIST) in Boulder, CO. While
the same optics are used between the two types of arrays, there are some
differences in the focal plane module designs. Both package designs are shown
in Figure 1 in an exploded view. The TiN array utilizes a gold-plated aluminum
package and machined Al feedhorns. Optical alignment is set by a combination
of pin-and-slot design and careful machining, while vibrational variation in
the waveguide gaps above the detectors is suppressed by using pogo-pins from
the bottom of the feedhorn array to hold the array against the module package.
More details can be found in [20].

In comparison, both Al arrays use gold-plated Si-platelet feedhorns with gold-
plated copper packaging. Optical alignment is set while warm by use of
alignment pins, verified visually under a microscope, and maintained through
cooling due to the matched coefficients of thermal contraction. The waveguide
gap is set by an interface plate and the detector array, feedhorn chokes,
interface wafer, and backing plate are held against the back of the Si
feedhorn array by flexible springs, in the form of BeCu fingerstock. This
design shares many elements in common with the array packaging used by TolTEC,
as described in [21].

Both feedhorns are based on the same numerically-optimized spline profile used
on TolTEC’s 1.1 mm array [22, 4], and the differences in performance are
expected to be minimal based on simulations and early measurements. As
suggested above, the different choice of feedhorn materials requires unique
mechanical alignment and assembly methods between the two array types. Lastly,
the interface PCB design was slightly modified for the Al arrays.

Figure 2: TiN pixel design (bottom right) showing two polarization-sensitive
detectors. (Bottom left) Al pixel design shown at a similar scale. Close-ups
of the respective absorbers are shown on the top, displaying both the
meandered Al absorber and the TiN absorbers with Al patches.

###  2.4 Pixel Designs

Both pixel types are lumped element polarimeters evolved from previous NIST
designs. A single pixel contains two detectors with front-side illuminated,
orthogonal antennas that are impedance-matched to the feedhorn-coupled
waveguide. The primary components include a polarization-sensitive antenna
that serves as both the inductor and a direct absorber, an interdigitated
capacitor (IDC) for coupling to the readout line, and an IDC to set the total
capacitance. On the backside, the wafer is deep-etched down to the 80-$\mu m$
device layer and deposited with an aluminum ground plane, making a quarter-
wavelength reflective backshort to improve the optical coupling. Sample
devices are shown in Figure 2.

The Al devices are passivated with a layer of amorphous silicon and have a
$T_{c}\sim 1.4$ K and sheet resistance of $R_{s}\sim 1$ $\Omega/\square$ (Ohms
per square). The TiN/Ti/TiN trilayer devices have a $T_{c}\sim 1.1$ K, and
$R_{s}\sim 90$ $\Omega/\square$. Due to Al having much lower normal
resistance, the Al inductor is meandered with finer traces (${\sim}1$ $\mu m$
vs. ${\sim}4$ $\mu m$ linewidth) (as shown in Figure 2) to better match the
waveguide impedance. To tune the desired absorber volume while balancing
responsivity and coupling efficiency, 100-nm thick patches of Al are placed
above the TiN multilayer absorber to act as a short without significantly
affecting the impedance as done in the TolTEC designs [4]. Finally, the Al
detectors have slightly larger capacitor geometries. Additional details can be
found in [4, 23, 24].

##  3 Discussion

Lab testing of individual witness pixels and full arrays is ongoing at NIST
and Cornell, and both detector designs are still planned for deployment.
Yields for both types of arrays are expected to be 95% or better following LED
mapping and post-fabrication editing [25], which is currently in progress for
all three arrays. Measured quality factors, responsivity, and noise have met
expectations [17], though it is worth noting that the Al detectors have
slightly higher internal quality factors under load (significantly higher when
dark). While both detectors are expected to return science-grade data, there
are several differences in performance that can be expected to impact
operation or final map-making.

Figure 3:  Typical response to changing tone power and bath temperature for
TiN (left) and Al (right) with a 10 dB offset between powers for readability.
The response of TiN is well fit accounting for nonlinear kinetic inductance
[26], leading to a monotonic frequency shift with both tone power and
temperature, while total Q decreases with increasing temperature and remains
constant with tone power. In contrast, the Al resonant frequency increases
between $-93$ dBm and $-87$ dBm, before decreasing at higher powers up to
bifurcation, while the Q continually increases with tone power. Similarly, the
Q and frequency increase with bath temperature up to ${\sim}220$ mK at all
powers. Tone power is estimated at the detector and should be accurate within
3 dB.

The noise profile of the two materials is distinct, particularly at low
frequencies, which is one of the features that motivated a shift towards Al
detectors. The Al detectors have been measured to have exceptionally low 1/f
noise [24], whereas the TiN have a higher photon-activated noise contribution
at low frequencies. This is particularly relevant for wide-field surveys and
reconstructing large angular scales, as for science cases involving the cosmic
microwave background.

Additionally, the different optical response curves of the materials has been
well documented [7, 27]. While TiN KIDs show an unexpectedly linear response
to optical illumination, Al detectors have a square-root dependence. This
means detector tuning requirements during observations may differ between
arrays.

One final point of discussion is the tone power sensitivity and nonlinearity.
Optimizing tone power is an integral part of achieving the highest signal-to-
noise for KIDs in the field. It is generally preferable to read out KIDs at
the highest tone powers attainable without reaching bifurcation, to both
maximize signal-to-noise going into the first-stage amplifier and minimize TLS
noise. On this count, it is useful that the Al detectors bifurcate at higher
tone powers. However, as a result of the interplay between the nonlinear
kinetic inductance [26] and nonequilibrium quasiparticle dynamics [28], the Al
detectors show more complicated interactions between tone power linearity,
optical loading, and the observed resonator parameters, requiring careful
tuning. Some of this is seen in Figure 3, which shows the non-monotonic
relationship between tone-power and measured resonant frequency and Q. This
also significantly distorts the resonator line shape, making it difficult to
fit for these parameters. This sensitivity to tone power will necessitate
frequent tuning as observing conditions vary, or resonator tone-tracking,
which is planned for implementation after deployment [29]. How this will
impact observing efficiency and on-sky noise performance remains to be seen.

##  4 Conclusion

The 280 GHz instrument module in Prime-Cam will be an exceptional opportunity
to directly compare the performance and practical operation of similarly
optimized Al and TiN KIDs. We have described the background of the detector
designs and several of the relevant features that are expected to
differentiate their performance. All three of the arrays have been fabricated
and are currently undergoing LED-mapping and post-fabrication editing to
achieve targeted on-sky yield [25]. Once completed, we will be able to fully
optically characterize the arrays, including measurements of polarization
efficiency, cross-polarization, responsivity, and noise prior to deployment in
Mod-Cam on FYST for commissioning.

Acknowledgments

The CCAT project, FYST and Prime-Cam instrument have been supported by
generous contributions from the Fred M. Young, Jr. Charitable Trust, Cornell
University, and the Canada Foundation for Innovation and the Provinces of
Ontario, Alberta, and British Columbia. The construction of the FYST telescope
was supported by the Großgeräte-Programm of the German Science Foundation
(Deutsche Forschungsgemeinschaft, DFG) under grant INST 216/733-1 FUGG, as
well as funding from Universität zu Köln, Universität Bonn and the Max Planck
Institut für Astrophysik, Garching. MDN acknowledges support from NSF grant
AST-2117631. EMV acknowledges support from NSF award AST-2202237. ZBH was
supported by a NASA Space Technology Graduate Research Opportunity. SKC
acknowledges support from NSF award AST2001866. SW acknowledges support from
the Cornell CURES fellowship.

## References

  *   * [1] Day, P.K., LeDuc, H.G., Mazin, B.A., Vayonakis, A., Zmuidzinas, J.: A broadband superconducting detector suitable for use in large arrays 425(6960), 817–821 https://doi.org/10.1038/nature02037 . Number: 6960 Publisher: Nature Publishing Group
  * [2] Dober, B.J., Ade, P.A.R., Ashton, P., Angilè, F.E., Beall, J.A., Becker, D., Bradford, K.J., Che, G., Cho, H.-M., Devlin, M.J., Fissel, L.M., Fukui, Y., Galitzki, N., Gao, J., Groppi, C.E., Hillbrand, S., Hilton, G.C., Hubmayr, J., Irwin, K.D., Klein, J., Lanen, J.V., Li, D., Li, Z.-Y., Lourie, N.P., Mani, H., Martin, P.G., Mauskopf, P., Nakamura, F., Novak, G., Pappas, D.P., Pascale, E., Santos, F.P., Savini, G., Scott, D., Stanchfield, S., Ullom, J.N., Underhill, M., Vissers, M.R., Ward-Thompson, D.: The next-generation BLASTPol experiment. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII, vol. 9153, pp. 137–148. SPIE. https://doi.org/10.1117/12.2054419 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/9153/91530H/The-next-generation-BLASTPol-experiment/10.1117/12.2054419.full
  * [3] Adam, R., Adane, A., Ade, P.A.R., André, P., Andrianasolo, A., Aussel, H., Beelen, A., Benoît, A., Bideaud, A., Billot, N., Bourrion, O., Bracco, A., Calvo, M., Catalano, A., Coiffard, G., Comis, B., Petris, M.D., Désert, F.-X., Doyle, S., Driessen, E.F.C., Evans, R., Goupy, J., Kramer, C., Lagache, G., Leclercq, S., Leggeri, J.-P., Lestrade, J.-F., Macías-Pérez, J.F., Mauskopf, P., Mayet, F., Maury, A., Monfardini, A., Navarro, S., Pascale, E., Perotto, L., Pisano, G., Ponthieu, N., Revéret, V., Rigby, A., Ritacco, A., Romero, C., Roussel, H., Ruppin, F., Schuster, K., Sievers, A., Triqueneaux, S., Tucker, C., Zylka, R.: The NIKA2 large-field-of-view millimetre continuum camera for the 30 m IRAM telescope 609, 115 https://doi.org/10.1051/0004-6361/201731503 . Publisher: EDP Sciences
  * [4] Austermann, J.E., Beall, J.A., Bryan, S.A., Dober, B., Gao, J., Hilton, G., Hubmayr, J., Mauskopf, P., McKenney, C.M., Simon, S.M., Ullom, J.N., Vissers, M.R., Wilson, G.W.: Millimeter-wave polarimeters using kinetic inductance detectors for TolTEC and beyond 193(3), 10–10071090901819495 https://doi.org/10.1007/s10909-018-1949-5
  * [5] Wheeler, J., Austermann, J., Vissers, M., Beall, J., Gao, J., Imrek, J., Heilweil, E., Bennett, D., Gard, J., Lanen, J.v., Hubmayr, J., Ullom, J.: Broadband kinetic inductance detectors for far-IR observations. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, vol. 12190, pp. 92–111. SPIE. https://doi.org/10.1117/12.2630672 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12190/1219006/Broadband-kinetic-inductance-detectors-for-far-IR-observations/10.1117/12.2630672.full
  * [6] Mauskopf, P.D., Doyle, S., Barry, P., Rowe, S., Bidead, A., Ade, P.A.R., Tucker, C., Castillo, E., Monfardini, A., Goupy, J., Calvo, M.: Photon-noise limited performance in aluminum LEKIDs 176(3), 545–552 https://doi.org/10.1007/s10909-013-1069-1
  * [7] Hubmayr, J., Beall, J., Becker, D., Cho, H.-M., Devlin, M., Dober, B., Groppi, C., Hilton, G.C., Irwin, K.D., Li, D., Mauskopf, P., Pappas, D.P., Van Lanen, J., Vissers, M.R., Wang, Y., Wei, L.F., Gao, J.: Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors 106(7), 073505 https://doi.org/10.1063/1.4913418
  * [8] Monfardini, A., Benoit, A., Bideaud, A., Swenson, L., Cruciani, A., Camus, P., Hoffmann, C., Désert, F.X., Doyle, S., Ade, P., Mauskopf, P., Tucker, C., Roesch, M., Leclercq, S., Schuster, K.F., Endo, A., Baryshev, A., Baselmans, J.J.A., Ferrari, L., Yates, S.J.C., Bourrion, O., Macias-Perez, J., Vescovi, C., Calvo, M., Giordano, C.: A dual-band millimeter-wave kinetic inductance camera for the IRAM 30 m telescope 194(2), 24 https://doi.org/%****␣article.bbl␣Line␣300␣****10.1088/0067-0049/194/2/24 . Publisher: The American Astronomical Society
  * [9] Paiella, A., Battistelli, E.S., Castellano, M.G., Colantoni, I., Columbro, F., Coppolecchia, A., D’Alessandro, G., Bernardis, P.d., Gordon, S., Lamagna, L., Mani, H., Masi, S., Mauskopf, P., Pettinari, G., Piacentini, F., Presta, G.: Kinetic inductance detectors and readout electronics for the OLIMPO experiment 1182(1), 012005 https://doi.org/10.1088/1742-6596/1182/1/012005 . Publisher: IOP Publishing
  * [10] Brien, T.L.R., Ade, P.A.R., Barry, P.S., Castillo-Domìnguez, E., Ferrusca, D., Gascard, T., Gómez, V., Hargrave, P.C., Hornsby, A.L., Hughes, D., Pascale, E., Parrianen, J.D.A., Perez, A., Rowe, S., Tucker, C., González, S.V., Doyle, S.M.: MUSCAT: the mexico-UK sub-millimetre camera for AsTronomy. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, vol. 10708, pp. 173–181. SPIE. https://doi.org/10.1117/12.2313697 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10708/107080M/MUSCAT-the-Mexico-UK-Sub-Millimetre-Camera-for-AsTronomy/10.1117/12.2313697.full
  * [11] Swenson, L.J., Day, P.K., Dowell, C.D., Eom, B.H., Hollister, M.I., Jarnot, R., Kovács, A., Leduc, H.G., McKenney, C.M., Monroe, R., Mroczkowski, T., Nguyen, H.T., Zmuidzinas, J.: MAKO: a pathfinder instrument for on-sky demonstration of low-cost 350 micron imaging arrays. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI, vol. 8452, pp. 190–199. SPIE. https://doi.org/10.1117/12.926223 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/8452/84520P/MAKO--a-pathfinder-instrument-for-on-sky-demonstration-of/10.1117/12.926223.full
  * [12] Wilson, G.W., Abi-Saad, S., Ade, P., Aretxaga, I., Austermann, J., Ban, Y., Bardin, J., Beall, J., Berthoud, M., Bryan, S., Bussan, J., Castillo, E., Chavez, M., Contente, R., DeNigris, N.S., Dober, B., Eiben, M., Ferrusca, D., Fissel, L., Gao, J., Golec, J.E., Golina, R., Gomez, A., Gordon, S., Gutermuth, R., Hilton, G., Hosseini, M., Hubmayr, J., Hughes, D., Kuczarski, S., Lee, D., Lunde, E., Ma, Z., Mani, H., Mauskopf, P., McCrackan, M., McKenney, C., McMahon, J., Novak, G., Pisano, G., Pope, A., Ralston, A., Rodriguez, I., Sánchez-Argüelles, D., Schloerb, F.P., Simon, S., Sinclair, A., Souccar, K., Campos, A.T., Tucker, C., Ullom, J., Camp, E.V., Lanen, J.V., Velazquez, M., Vissers, M., Weeks, E., Yun, M.S.: The TolTEC camera: an overview of the instrument and in-lab testing results. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, vol. 11453, p. 1145302. SPIE. https://doi.org/10.1117/12.2562331 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11453/1145302/The-TolTEC-camera--an-overview-of-the-instrument-and/10.1117/12.2562331.full
  * [13] Mazin, B.A., Meeker, S.R., Strader, M.J., Szypryt, P., Marsden, D., Eyken, J.C.v., Duggan, G.E., Walter, A.B., Ulbricht, G., Johnson, M., Bumble, B., O’Brien, K., Stoughton, C.: ARCONS: A 2024 pixel optical through near-IR cryogenic imaging spectrophotometer 125(933), 1348 https://doi.org/10.1086/674013 . Publisher: IOP Publishing
  * [14] Parshley, S.C., Kronshage, J., Blair, J., Herter, T., Nolta, M., Stacey, G.J., Bazarko, A., Bertoldi, F., Bustos, R., Campbell, D.B., Chapman, S., Cothard, N., Devlin, M., Erler, J., Fich, M., Gallardo, P.A., Giovanelli, R., Graf, U., Gramke, S., Haynes, M.P., Hills, R., Limon, M., Mangum, J.G., McMahon, J., Niemack, M.D., Nikola, T., Omlor, M., Riechers, D.A., Steeger, K., Stutzki, J., Vavagiakis, E.M.: CCAT-prime: a novel telescope for sub-millimeter astronomy. In: Ground-based and Airborne Telescopes VII, vol. 10700, pp. 1744–1758. SPIE. https://doi.org/10.1117/12.2314046 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10700/107005X/CCAT-prime-a-novel-telescope-for-sub-millimeter-astronomy/10.1117/12.2314046.full
  * [15] Niemack, M.D.: Designs for a large-aperture telescope to map the CMB 10× faster 55(7), 1688–1696 https://doi.org/10.1364/AO.55.001688 . Publisher: Optica Publishing Group
  * [16] Vavagiakis, E.M., Ahmed, Z., Ali, A., Basu, K., Battaglia, N., Bertoldi, F., Bond, R., Bustos, R., Chapman, S.C., Chung, D., Coppi, G., Cothard, N.F., Dicker, S., Duell, C.J., Duff, S.M., Erler, J., Fich, M., Galitzki, N., Gallardo, P.A., Henderson, S.W., Herter, T.L., Hilton, G., Hubmayr, J., Irwin, K.D., Koopman, B.J., McMahon, J., Murray, N., Niemack, M.D., Nikola, T., Nolta, M., Orlowski-Scherer, J., Parshley, S.C., Riechers, D.A., Rossi, K., Scott, D., Sierra, C., Silva-Feaver, M., Simon, S.M., Stacey, G.J., Stevens, J.R., Ullom, J.N., Vissers, M.R., Walker, S., Wollack, E.J., Xu, Z., Zhu, N.: Prime-cam: a first-light instrument for the CCAT-prime telescope. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, vol. 10708, pp. 375–390. SPIE. https://doi.org/10.1117/12.2313868 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10708/107081U/Prime-Cam--a-first-light-instrument-for-the-CCAT/10.1117/12.2313868.full
  * [17] Collaboration, C.-P., Aravena, M., Austermann, J.E., Basu, K., Battaglia, N., Beringue, B., Bertoldi, F., Bigiel, F., Bond, J.R., Breysse, P.C., Broughton, C., Bustos, R., Chapman, S.C., Charmetant, M., Choi, S.K., Chung, D.T., Clark, S.E., Cothard, N.F., Crites, A.T., Dev, A., Douglas, K., Duell, C.J., Dünner, R., Ebina, H., Erler, J., Fich, M., Fissel, L.M., Foreman, S., Freundt, R.G., Gallardo, P.A., Gao, J., García, P., Giovanelli, R., Golec, J.E., Groppi, C.E., Haynes, M.P., Henke, D., Hensley, B., Herter, T., Higgins, R., Hložek, R., Huber, A., Huber, Z., Hubmayr, J., Jackson, R., Johnstone, D., Karoumpis, C., Keating, L.C., Komatsu, E., Li, Y., Magnelli, B., Matthews, B.C., Mauskopf, P.D., McMahon, J.J., Meerburg, P.D., Meyers, J., Muralidhara, V., Murray, N.W., Niemack, M.D., Nikola, T., Okada, Y., Puddu, R., Riechers, D.A., Rosolowsky, E., Rossi, K., Rotermund, K., Roy, A., Sadavoy, S.I., Schaaf, R., Schilke, P., Scott, D., Simon, R., Sinclair, A.K., Sivakoff, G.R., Stacey, G.J., Stutz, A.M., Stutzki, J., Tahani, M., Thanjavur, K., Timmermann, R.A., Ullom, J.N., Engelen, A.v., Vavagiakis, E.M., Vissers, M.R., Wheeler, J.D., White, S.D.M., Zhu, Y., Zou, B.: CCAT-prime collaboration: Science goals and forecasts with Prime-Cam on the Fred Young Submillimeter Telescope 264(1), 7 https://doi.org/10.3847/1538-4365/ac9838 . Publisher: The American Astronomical Society
  * [18] Choi, S.K., Austermann, J., Basu, K., Battaglia, N., Bertoldi, F., Chung, D.T., Cothard, N.F., Duff, S., Duell, C.J., Gallardo, P.A., Gao, J., Herter, T., Hubmayr, J., Niemack, M.D., Nikola, T., Riechers, D., Rossi, K., Stacey, G.J., Stevens, J.R., Vavagiakis, E.M., Vissers, M., Walker, S.: Sensitivity of the Prime-Cam instrument on the CCAT-prime telescope 199(3), 1089–1097 https://doi.org/10.1007/s10909-020-02428-z
  * [19] Vavagiakis, E.M., Duell, C.J., Austermann, J., Beall, J., Bhandarkar, T., Chapman, S.C., Choi, S.K., Coppi, G., Dicker, S., Devlin, M., Freundt, R.G., Gao, J., Groppi, C., Herter, T.L., Huber, Z.B., Hubmayr, J., Johnstone, D., Keller, B., Kofman, A.M., Li, Y., Mauskopf, P., McMahon, J., Moore, J., Murphy, C.C., Niemack, M.D., Nikola, T., Orlowski-Scherer, J., Rossi, K.M., Sinclair, A.K., Stacey, G.J., Ullom, J., Vissers, M., Wheeler, J., Xu, Z., Zhu, N., Zou, B.: CCAT-prime: design of the mod-cam receiver and 280 GHz MKID instrument module. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, vol. 12190, pp. 61–76. SPIE. https://doi.org/10.1117/12.2630115 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12190/1219004/CCAT-prime--design-of-the-Mod-Cam-receiver-and/10.1117/12.2630115.full
  * [20] Duell, C.J., Vavagiakis, E.M., Austermann, J., Chapman, S.C., Choi, S.K., Cothard, N.F., Dober, B., Gallardo, P., Gao, J., Groppi, C., Herter, T.L., Stacey, G.J., Huber, Z., Hubmayr, J., Johnstone, D., Li, Y., Mauskopf, P., McMahon, J., Niemack, M.D., Nikola, T., Rossi, K., Simon, S., Sinclair, A.K., Vissers, M., Wheeler, J., Zou, B.: CCAT-prime: Designs and status of the first light 280 GHz MKID array and mod-cam receiver. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, vol. 11453, pp. 235–243. SPIE. https://doi.org/10.1117/12.2562757 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11453/114531F/CCAT-prime--Designs-and-status-of-the-first-light/10.1117/12.2562757.full
  * [21] Austermann, J.E., Ban, Y., Beall, J., Berthoud, M., Contente, R., DeNigris, N., Dober, B., Gao, J., Hilton, G., Hubmayr, J., Kuczarski, S., Lee, D., Lunde, E., Ma, Z., Mauskopf, P., McCrackan, M., McKenney, C., McMahon, J., Novak, G., Abi-Saad, S., Simon, S., Souccar, K., Ullom, J., Camp, E.V., Lanen, J.V., Vissers, M., Wilson, G.: TolTEC focal plane arrays: design, characterization, and performance of kilopixel MKID focal planes. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, vol. 11453, p. 114530. SPIE. https://doi.org/10.1117/12.2562086 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/11453/114530A/TolTEC-focal-plane-arrays--design-characterization-and-performance-of/10.1117/12.2562086.full
  * [22] Simon, S.M., Golec, J.E., Ali, A., Austermann, J., Beall, J.A., Bruno, S.M.M., Choi, S.K., Crowley, K.T., Dicker, S., Dober, B., Duff, S.M., Healy, E., Hill, C.A., Ho, S.-P.P., Hubmayr, J., Li, Y., Lungu, M., McMahon, J., Orlowski-Scherer, J., Salatino, M., Staggs, S., Wollack, E.J., Xu, Z., Zhu, N.: Feedhorn development and scalability for simons observatory and beyond. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy IX, vol. 10708, pp. 1145–1156. SPIE. https://doi.org/10.1117/12.2313405 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10708/107084B/Feedhorn-development-and-scalability-for-Simons-Observatory-and-beyond/10.1117/12.2313405.full
  * [23] Choi, S.K., Duell, C.J., Austermann, J., Cothard, N.F., Gao, J., Freundt, R.G., Groppi, C., Herter, T., Hubmayr, J., Huber, Z.B., Keller, B., Li, Y., Mauskopf, P., Niemack, M.D., Nikola, T., Rossi, K., Sinclair, A., Stacey, G.J., Vavagiakis, E.M., Vissers, M., Tucker, C., Weeks, E., Wheeler, J.: CCAT-prime: Characterization of the first 280 GHz MKID array for prime-cam 209(5), 849–856 https://doi.org/10.1007/s10909-022-02787-9
  * [24] Austermann, J.E., Beall, J., Gao, J., Hubmayr, J., Ullom, J., Vissers, M., Wheeler, J.: Aluminum-based millimeter-wave kinetic inductance detectors on 150~mm diameter substrates. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, vol. PC12190, p. 121900. SPIE. https://doi.org/10.1117/12.2630512 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/PC12190/PC121900X/Aluminum-based-millimeter-wave-kinetic-inductance-detectors-on-150mm-diameter/10.1117/12.2630512.full
  * [25] Liu, X., Guo, W., Wang, Y., Dai, M., Wei, L.F., Dober, B., McKenney, C.M., Hilton, G.C., Hubmayr, J., Austermann, J.E., Ullom, J.N., Gao, J., Vissers, M.R.: Superconducting micro-resonator arrays with ideal frequency spacing 111(25), 252601 https://doi.org/10.1063/1.5016190
  * [26] Swenson, L.J., Day, P.K., Eom, B.H., Leduc, H.G., Llombart, N., McKenney, C.M., Noroozian, O., Zmuidzinas, J.: Operation of a titanium nitride superconducting microresonator detector in the nonlinear regime 113(10), 104501 https://doi.org/10.1063/1.4794808
  * [27] Flanigan, D., McCarrick, H., Jones, G., Johnson, B.R., Abitbol, M.H., Ade, P., Araujo, D., Bradford, K., Cantor, R., Che, G., Day, P., Doyle, S., Kjellstrand, C.B., Leduc, H., Limon, M., Luu, V., Mauskopf, P., Miller, A., Mroczkowski, T., Tucker, C., Zmuidzinas, J.: Photon noise from chaotic and coherent millimeter-wave sources measured with horn-coupled, aluminum lumped-element kinetic inductance detectors 108(8), 083504 https://doi.org/10.1063/1.4942804
  * [28] Visser, P.J., Goldie, D.J., Diener, P., Withington, S., Baselmans, J.J.A., Klapwijk, T.M.: Evidence of a nonequilibrium distribution of quasiparticles in the microwave response of a superconducting aluminum resonator 112(4), 047004 https://doi.org/10.1103/PhysRevLett.112.047004 . Publisher: American Physical Society
  * [29] Sinclair, A.K., Stephenson, R.C., Roberson, C.A., Weeks, E.L., Burgoyne, J., Huber, A.I., Mauskopf, P.M., Chapman, S.C., Austermann, J.E., Choi, S.K., Duell, C.J., Fich, M., Groppi, C.E., Huber, Z., Niemack, M.D., Nikola, T., Rossi, K.M., Sriram, A., Stacey, G.J., Szakiel, E., Tsuchitori, J., Vavagiakis, E.M., Wheeler, J.D.: CCAT-prime: RFSoC based readout for frequency multiplexed kinetic inductance detectors. In: Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI, vol. 12190, pp. 444–463. SPIE. https://doi.org/10.1117/12.2629722 . https://www.spiedigitallibrary.org/conference-proceedings-of-spie/12190/121900W/CCAT-prime--RFSoC-based-readout-for-frequency-multiplexed-kinetic/10.1117/12.2629722.full