Matthaeus Leitner

The Large Aperture Telescope (LAT) receiver engineering group has developed a first thermal model of the 50 K radiation shield. Due to the large receiver size this sub-component is challenging to design. The shield supports the alumina IR filters which need to be sufficiently cooled. Several options are currently being investigated to reduce thermal gradients, e.g. improved heat straps or higher conductivity materials. The figures below show the thermal model of the LAT receiver cryostat.

 

Key Dates and Upcoming Activities

The project and collaboration have recently completed the Analysis of Alternatives. This allows us to refocus the project to developing a new project baseline for future reviews. We presented our strong and further strengthened science case to the P5 Particle Physics Project Prioritization Panel.

• CMB-S4 Spring Collaboration Meeting – April 3 – 6, 2023
• CMB-S4 Summer Collaboration Meeting – week of July 31 – Aug 4, 2023

 

Originally posted in the CMB-S4 February 2023 Newsletter

Fermilab, SLAC, Washington University in St. Louis, and University of Illinois Urbana-Champaign have set up module test cryostats to qualify future CMB-S4 prototype wafers and module components including readout electronics. Fig. 1, below, shows a single wafer test cryostat (cryogenic black-body cold load). Fig. 2 shows Ian Gullett (Case Western) and Cesiley King (WashU) and a newly installed cold load, which is used to measure the optical efficiency of detector modules, at Washington University.

Originally posted in the CMB-S4 February 2023 Newsletter

CMB-S4 detector wafer fabrication sites continue to optimize prototype pixel layouts and critical sub-component fabrication methods. Our industrial partner, SEEQC, has successfully produced a full prototype wafer for the Small Aperture Telescope (SAT) mid-frequency range. L3 system manager, Aritoki Suzuki, can be seen in the below image reflected within the intricate detector pattern. A zoomed in photo of the pixel layout is shown in the second photo. As a next step, the circular wafer will be diced into a hexagonal shape and subsequently tested in a dilution refrigerator cryostat at LBNL. CMB-S4 aims to prototype wafer types in key frequency ranges before finalizing the experiment’s conceptual detector designs.

 

Originally posted in the CMB-S4 February 2023 Newsletter