Balloon-borne Cosmic Microwave Background experiments

Abstract

Stratospheric balloon experiments play a unique role in current Cosmic Microwave Background (CMB) studies. CMB research has entered a precision phase, harvesting the detailed properties of its anisotropy, polarization and spectrum, at incredible precision levels. These measurements, however, require careful monitoring and subtraction of local backgrounds, produced by the earth atmosphere and the interstellar medium. High frequencies (larger than 180 GHz) are crucial for the measurements of interstellar dust contamination, but are degraded by atmospheric emission and its fluctuations, even in the best (cold and dry) sites on earth. For this reason, new balloon-borne missions, exploiting long-duration and ultra-long duration stratospheric flights, are being developed in several laboratories worldwide. These experiments have the double purpose of qualifying instrumentation and validating methods to be used on satellite missions, and produce CMB science at a relatively fast pace, synergically to ground-based CMB observatories.

Sensitivity of LEKID for space applications between 80 GHz and 600 GHz

“…4.3). For space instruments that are exposed to a considerable flux of primary cosmic rays, the response time is a crucial parameter (Masi et al 2019;Catalano et al 2016).…”

Selective Laser Melting Process of Al–Based Pyramidal Horns for the W-Band: Fabrication and Testing

“…On the other hand, it is also prone to intrinsic limitations in view of applications in millimeter-wave astronomy: Cu-based components are comparatively heavy and therefore not easily implemented in the large-format cryogenic focal planes of millimeter-wave telescopes, which often feature close-packings of hundreds to thousands of such devices. For these applications, the preference shifts toward lighter materials (such as aluminum) especially if instruments are hosted on balloon-borne platforms [16,21], where weight containment is a key factor in payload design. More importantly, modern detector technologies for millimeter-wave astronomy rely on superconducting cryogenic sensors operated at temperatures of a few hundreds of mK, for which the readout is often sensitive to external magnetic fields and highly benefit from magnetic shielding by superconducting housings and enclosures.…”

The long duration cryogenic system of the OLIMPO balloon–borne experiment: Design and in–flight performance

“…The best way to explore the whole spectral region of interest for the CMB is to operate instruments with no hindrance from the atmospheric opacity in the microwaves, either by flying them on satellites, or by keeping them at very high altitude on sub-orbital platforms, like rockets and stratospheric balloons [4].…”

“…Vapors from the 4 He boiloff flow through a serpentine welded on a copper shield placed between the two tanks, cooling it at an intermediate temperature, close to 35 K (with a temperature of the nitrogen tank at 77 K) and close to about 21 K in flight (when the temperature of the nitrogen tank is around 52 K).…”

“…The 4 He stage has been built with a cylindrical shape, where the available liquid reduces to about 50 % of the full volume after the pump-down operation needed to reach a temperature of 1.65 K. The main purpose of the 4 He tank in the OLIMPO cryostat is to cool down the reimaging optics and to provide the thermal reference stage for the condensation point of the 3 He evaporative sorption refrigerator. This refrigerator has been customdesigned to work on the stratospheric balloon payload and to cool to 300 mK the focal planes of the experiment for about two weeks without being recycled.…”