The E and B Experiment (EBEX) was a long-duration balloon-borne instrument designed to measure the polarization of the cosmic microwave background (CMB) radiation. EBEX was the first balloon-borne instrument to implement a kilopixel array of transition edge sensor (TES) bolometric detectors and the first CMB experiment to use the digital version of the frequency domain multiplexing system for readout of the TES array. The scan strategy relied on 40 s peak-to-peak constant-velocity azimuthal scans. We discuss the unique demands on the design and operation of the payload that resulted from these new technologies and the scan strategy. We describe the solutions implemented, including the development of a power system designed to provide a total of at least 2.3 kW, a cooling system to dissipate 590 W consumed by the detectors' readout system, software to manage and handle the data of the kilopixel array, and specialized attitude reconstruction software. We present flight performance data showing faultless management of the TES array, adequate powering and cooling of the readout electronics, and constraint of attitude reconstruction errors such that the spurious B-modes they induced were less than 10% of the CMB B-mode power spectrum with r = 0.05.
Bibliographical noteFunding Information:
Support for the development and flight of the EBEX instrument was provided by NASA grants NNX12AD50G, NNX13AE49G, NNX08AG40G, and NNG05GE62G and by NSF grants AST-0705134 and ANT-0944513. P.A., L.M., E.P., and C.T. acknowledge the Science & Technology Facilities Council for its continued support of the underpinning technology for filter and wave plate development. We also acknowledge support by the Canada Space Agency, the Canada Research Chairs Program, the Natural Sciences and Engineering Research Council of Canada, the Canadian Institute for Advanced Research, the Minnesota Supercomputing Institute at the University of Minnesota, the National Energy Research Scientific Computing Center, the Minnesota and Rhode Island Space Grant Consortia, our collaborating institutions, and Sigma Xi, The Scientific Research Society. C.B. acknowledges support by the RADIOFOREGROUNDS project, funded by the European Commissions H2020 Research Infrastructures under grant agreement no. 687312, as well as the Italian INFN INDARK initiative. J.D. acknowledges a NASA NESSF fellowship NNX11AL15H. K.H. acknowledges NASA NSTRF fellowship NNX11AN35H. B.R.-K. acknowledges an NSF Post-Doctoral Fellowship AST-1102774 and a NASA Graduate Student Research Fellowship. K.R. and K.Z. acknowledge support by the Minnesota Space Grant Consortium. We very much thank Danny Ball and his colleagues at the Columbia Scientific Balloon Facility for their dedicated support of the EBEX program. We thankfully acknowledge contributions to predicting systematic errors by Matias Zaldarriaga and Amit Yadav. We thank the BLAST team for providing the original version of the flight computer program discussed in Section 4. We thank Christopher Geach, Qi Wen, and Xin Zhi Tan for help with figures.
- cosmic background radiation
- cosmology: observations
- instrumentation: polarimeters