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The CMB-S4 Director’s Review was held on November 14-17, 2023, to assess the project’s readiness in preparation for Department of Energy (DOE) and National Science Foundation (NSF) conceptual design reviews, both anticipated in 2024.

CMB-S4 (the Cosmic Microwave Background Experiment – Stage 4) is a next-generation experiment being pursued as a joint DOE and NSF project to precisely map the cosmic microwave background with unprecedented sensitivity. CMB-S4 will answer key questions about the origin of our Universe. (Click on the CMB-S4 Infographic, right, to learn more.)

The project was recommended as a high priority in the National Academies Decadal Survey on Astronomy and Astrophysics 2020 (Astro2020) and as a top priority in the 2023 P5 Report recommendations, released last week. Once past the conceptual design phase, the project will proceed to the detailed engineering design of the 12 state-of-the-art microwave telescopes, which will survey the sky with close to 500,000 cryogenically-cooled superconducting detectors, located at the best sites for CMB observation in the Chilean Andes and at the South Pole.

The external review committee consisted of experts from academic and research organizations nationwide. Natalie Roe, Associate Laboratory Director for Physical Sciences, welcomed participants and encouraged the committee to review the project with ‘a fine-toothed comb’ and to provide the invaluable and constructive feedback needed to guide the project towards success in the next level of reviews.>

The Director’s Review lasted four days with three full days of presentations by the project team. The committee evaluated science requirements and systems engineering approaches plus technical design decisions and progress to date across all CMB-S4 subsystems. Construction, installation, and commissioning plans at the remote observing sites were also reviewed. In addition, strategies for the highly advanced data analysis pipeline to evaluate the CMB signals were discussed. Two separate subcommittees evaluated project cost and schedule plus the management team of this large and complex project.>

CMB-S4 Project Manager Matthaeus Leitner hosted the review and coordinated the team’s presentations. “It is a great pleasure to work with such a distinguished team of CMB scientists and engineers who have optimized the experiment design over many years of diligent work. Big project reviews are a strenuous effort, and I want to thank everyone for their dedication to CMB-S4 and for helping us push the project forward.”>

In their final report, issued on November 30, the review committee congratulated the project team on the impressive progress that has been made since the previous Director’s Review in November 2021, especially in light of the limited funds available. The committee complimented the project team’s exceptional work on the science-driven technical design, their “strong and experienced” management team, as well as various documentation and planning elements that are “very advanced for this stage” in the project’s review process.>

“These reviews are critical milestones in a big project like CMB-S4,” said Roe. “The extensive preparations help to focus the team, and the in-depth discussions and recommendations provide crucial guidance to keep the project on track. This review was very successful in all of these aspects.”

CMB-S4 Project Director Jim Strait, who has a long history of managing large international scientific projects, is enthusiastic about the outcomes of the review and the committee’s constructive recommendations. “The Director’s Review was very successful,” Strait said.  “It both validated that we are on track for upcoming funding agency reviews and gave us many recommendations and words of advice that will ensure that we will be ready for the NSF and DOE reviews once they are scheduled. The Review Committee was fantastic.  They were very constructive in their interactions with us while holding our feet to the fire.”

The National Science Foundation (NSF) has awarded up to $21.4 million for the design of telescopes for CMB-S4, a next-generation experiment that will study the cosmic microwave background (CMB) and help us understand the beginning, history, and makeup of the universe.

The CMB-S4 project, which is jointly supported by the Department of Energy and the National Science Foundation, currently involves an international collaboration of 450 scientists from more than 100 institutions spanning 20 countries. Berkeley Lab leads the partnership of national labs, universities, and institutions that will carry out the project for DOE. In addition to providing the overall project management infrastructure, Berkeley Lab also plays a lead role in technology development for the experiment’s superconducting detectors, small-aperture telescopes, and data management. CMB-S4 is expected to cost on the order of $800 million and to come fully online in the early 2030s.

Read the full article:
Experiment to Capture Universe’s Earliest Moments Reaches Funding Milestone
October 26, 2023 / Berkeley Lab News Center
(Adapted from a news release by the University of Chicago)

CMB-S4 Project Director Jim Strait recently announced Level-2 and Level-3 management team changes for the detectors team.

Aritoki Suzuki – staff scientist in Berkeley Lab’s Physics Division since 2017– will become the Level-2 Scientist for the CMB-S4 detector subsystem. Suzuki brings a wealth of technical knowledge to CMB detector design, fabrication, and testing, and he has previously worked on detector arrays for POLARBEAR-2, the Simons Array, SPT-3G, LiteBIRD, CMB-S4, and other experiments. He also has experience with readout electronics and currently serves as Level-2 Manager of the antenna modules for the LuSEE-Night project.

Kelly Hanzel will become the Level-2 Control Account Manager (CAM) for the CMB-S4 detector subsystem. Hanzel has worked at Berkeley Lab as a QA/manufacturing engineer and project manager since 2011, cultivating expertise with several DOE projects including LCLS-II, ALS-U, and LCLS-II HE She also served as the deputy project manager and then project manager to successfully guide the LUX-ZEPLIN (LZ) project (a dark matter detector now operating deep underground in South Dakota) from pre-CD-2 through completion at CD-4.

Rebecca Carney will become the Level-3 Manager for the LBNL-SEEQC segment of CMB-S4’s detector subsystem. Currently a staff engineer in the Electronics, Software, and Instrumentation Engineering (ESIE) Department of Berkeley Lab’s Engineering Division, Carney did her PhD with the ATLAS experiment searching for long-lived particles and developing radiation hard pixel detectors for the HL-LHC. As a postdoc on the LEGEND experiment, she designed a monitoring and control system for the Ge-readout electronics and fabricated over 150 high-radiopurity front-ends in the Nuclear Science Division’s Semiconductor Detector Lab, which form the first link in the detector readout chain for LEGEND-200.

CMB-S4 is pleased to welcome this new leadership team. Suzuki, Hanzel, and Carney will assume their new roles starting in mid-September 2023.

Several CMB-S4 technical subsystems made important advancements during the last few months. The project is entering an exciting development phase.

The Module Assembly and Testing team at Fermilab was able to start the first 100 mK test of an integrated detector module including a detector wafer and readout module. Fig. 1 (below) shows the test setup which required a few cool-down iterations before it became fully operational. The arrangement contains a full detector module assembly with interface wafers, horn arrays, and wafer cooling connections. A 100 mK readout enclosure is mounted adjacent to the wafer. Three similar cryostat configurations (at UIUC, SLAC, and FNAL) are now operational and able to test CMB-S4 prototype detector modules.

We can also report notable successes on the detector design side: NIST characterized several LAT-MF prototype single pixel designs plus a CMB-S4 dual-TES bolometer chip. Fig. 2 (below) highlights the NIST single pixel measurement apparatus which utilizes an adiabatic demagnetization refrigerator (ADR). The unique setup allows qualification of passbands, optical efficiency, and polarization responses. Fig. 2 also shows the compact test-board which enables measuring several discrete pixel configurations in a single cool-down. This approach permits rapid development of different design iterations.

A first SEEQC full SAT-MF wafer prototype test was completed at LBNL (see Fig. 3, below), and dark bolometer data were extracted. Based on these results, SEEQC fabricated a second prototype wafer with further tuned annealing properties to raise the critical temperature of the AlMn transition edge sensors.

The recent Summer Collaboration meeting at SLAC focused on the future publication of a second edition of the CMB-S4 Science Book. SLAC organized an excellent gathering, and the opportunity to discuss topics in person strengthened our collaboration. It was great seeing everyone!

 

Originally posted in the CMB-S4 July-August 2023 Newsletter

The CMB-S4 South Pole Large Aperture Telescope (SPLAT) team has recently authored two key scientific publications [ref. 1, ref. 2] related to the telescope and mirror designs and is working on a third publication describing the detailed optics design. In addition, Eric Chauvin Consulting has submitted to the project a SPLAT preliminary engineering design report which includes mechanical design details as well as engineering analysis. In Fig. 1, below, the SPLAT design, originally conceived by S. Padin [ref. 3] is based on a three-mirror anastigmat design with a large field of view. To reduce systemic errors the telescope incorporates co-moving shields, boresight rotation, and monolithic aluminum mirrors.

Fig. 2, below, is an example of the SPLAT structural analysis evaluating deflections and pointing errors. The image shows modal analysis results displaying the mount’s first resonance shape.

The South Pole Large Aperture Telescope incorporates a novel combination of features which will allow CMB measurements over a wide range of angular scales. The telescope’s large (~5 m) primary mirror provides the necessary angular resolution to determine the angular distortions in CMB caused by gravitational lensing from the large scale structure in the universe. These distortions lead to a low level of B-mode polarization signal that must be subtracted from the CMB measurements to detect the primordial B-mode signal. As a novel development, the telescope will provide exceptional control of systematic errors by providing co-moving shields and baffles, boresight rotation capability, and uniquely fabricated monolithic aluminum mirrors. The combination of these new features will enable unprecedented levels of sensitivity for LAT measurements of B-mode polarization on large angular scales. Fig. 3, below, shows the optical layout of the three mirror anastigmat configuration (left) plus lens arrangement of the 85 receiver optics tubes (right) located at the telescope’s final focus.

Recently, a full-scale prototype monolithic mirror was machined to required precision and delivered to the University of Chicago. Deformation tests including a mirror support structure will be performed in the near future. The photos below show the recently-completed SPLAT prototype mirror. The upper image shows the surface of the mirror after machining while the lower image shows the structural support on the backside of the mirror.

Key Dates and Upcoming Activities

The project started preparations for a Director’s Review at LBNL (November 14th to 17th, 2023). A
sequence of external subsystem conceptual design reviews is also planned for late summer to fall.
Thanks to everyone who supports the preparations for these reviews!

• CMB-S4 Summer Collaboration Meeting (at SLAC) – July 31 – Aug 3, 2023
• Subsystem Conceptual Design Reviews – July – September, 2023
• Director’s Review (at LBNL) – November 14 – 17, 2023

 

Originally posted in the CMB-S4 June 2023 Newsletter