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A DUAL mission for nuclear astrophysics


DUAL will study the origin and evolution of the elements and explores new frontiers of physics: extreme energies that drive powerful stellar explosions and accelerate particles to macroscopic energies; extreme densities that modify the laws of physics around the most compact objects known; and extreme fields that influence matter in a way that is unknown on Earth. The variability of these extreme objects requires continuous all-sky coverage, while detailed study demands an improvement in sensitivity over previous technologies by at least an order of magnitude. The DUAL payload is composed of an All-Sky Compton Imager (ASCI), and two optical modules, the Laue-Lens Optic (LLO) and the Coded-Mask Optic (CMO). The ASCI serves dual roles simultaneously, both as an optimal focal-plane sensor for deep observations with the optical modules and as a sensitive true all-sky telescope in its own right for all-sky surveys and monitoring. While the optical modules are located on the main satellite, the All-Sky Compton Imager is situated on a deployable structure at a distance of 30 m from the satellite. This configuration not only permits to maintain the less massive payload at the focal distance, it also greatly reduces the spacecraft-induced detector background, and, above all it provides ASCI with a continuous all-sky exposure.

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We acknowledge the support of THALES ALENIA Cannes, SENER Madrid and Bilbao, CANBERRA Lingolsheim in the preparation of the technical part of this proposal. The proposal has also benefit from the results of the phase 0 study conducted by CNES in the context of the MAX project, and from the results of the Technical Reference Study conducted by ESA in the context of the GRL project. Technical developments in the context of DUAL are financially supported by ASI (contract I/088/06/0), CNES (lens R&D contracts 02/0551/01-DPI120 and DCT/SA/AB No 07-3202, R-S06/- and R-S09/SU-0002-025, and R-S06/SU-0002-026), ESA (ESTEC contract 20357/07/NL/NR) and the Spanish Ministry of Science and Innovation. A.B. was supported by the RAS programms, Russian government grant 11.G34.31.0001 to the Saint-Petersburg State Politechnical University, and by the RFBR 11-02-12082-ofi-m-2011.

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Back-of-the-envelope estimate for the sensitivity improvement, comparing the SPI sensitivity with ASCI

  mean  eff at 1 MeV T obs BGD at 1 MeV Sensitivity gain
INTEGRAL/SPI 65 cm2 106 s ∼0.1 c/s·kev  
DUAL/ASCI ∼51 cm2 9.5·107 s ∼7.3·10 − 3 c/s·kev  
Improvement ∼ vasci/spi 0.88 9.7 3.7 32

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The DUAL Consortium., von Ballmoos, P., Alvarez, J. et al. A DUAL mission for nuclear astrophysics. Exp Astron 34, 583–622 (2012).

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  • Nuclear astrophysics
  • Gamma-ray optics: Compton telescope
  • Laue lens
  • Coded aperture imaging
  • Second cosmic vision call of ESA