Positronium formation and annihilation in aerogels: Toward new space application concepts
Aerogels-lightweight highly porous insulator materials - have unique combination of properties, which makes them attractive for space applications. Aerogels can be made with a desired specific gravity varying from～3 mg/cm3 to >300 mg/cm3, thus producing a tunable degree of porosity (>90％) with fully interconnected network. This, in conjunction with their enormous surface area (of the order of 100-1000 m2/g) and high gas permeability, makes them ideally suited for molecule or charge storage applications. Furthermore, the surface can for chemically functionalized to selectively adsorb chosen species. We study Ps formation and annihilation in aerogels, especially the sensitivity of the Ps probe to specific electron environments that strongly compete with the free Ps annihilation in the pores. Such a Ps-aerogel system can be used to devise detection methods of moieties with relevance to various space applications, ranging from planetary sample return missions (organics), to life detection (byproducts), to human exploration (fuel components, dangerous chemicals). It is perceived that this method is equally suited for use in places with virtually non-existent atmosphere (e.g., the moon), as well as in Mars atmosphere (~7 Torr CO2). Back-of-the-envelope calculations show that the sensitivity limits to some moieties can reach ppm levels, thus rivalling the presently preferred surface-enhanced Raman and infrared methods. This work is in its early exploration stages.
M.P.Petkov S.M.Jones
Jet Propulsion Laboratory,California Inst.of Technology,Pasadena,CA 91109,U.S.A.
国际会议
第九届国际正电子与正电子素国际会议(9th International Workshop on Positron and Positronium Chemistry)(PPC–9)
武汉
英文
119
2008-05-11（万方平台首次上网日期，不代表论文的发表时间）