Search for low-energy nuclear transitions in laser-produced plasma

Abstract

The possibility to excite low-energy nuclear states using laser induced plasma on the Prague Asterix Laser System PALS is investigated. This medium-energy high-power facility yields interaction intensities at the level of 10 16 ÷ 10 17 Wcm −2 thus producing subrelativistic plasmas with electron temperature of the order of 1 ÷ 10 keV. Based on a systematic survey of suitable candidate nuclei, the search for the 6.238 keV excitation and decay in 181 Ta has been initiated. Tests and preliminary operation of detecting systems including active detectors are reported. 29.30.Kv, 42.55.Vc, 1 Sub-relativistic plasma-nuclear interactions Studies of photo-nuclear reactions induced by high-power lasers have become one of the most intensively developing disciplines of contemporary high-energydensity physics [1]. While ultra-intense laser systems generate relativistic electrons (which, primarily after their conversion to high-energy rays, may initiate photonuclear processes) and energetic neutrons, protons, and heavy ions capable of inducing fusion reactions, the laser-matter interactions at intensities up to 10 16 ÷ 10 17 W cm −2 (available at medium-size laser systems such as the Prague Asterix Laser System PALS [2]) produce subrelativistic plasmas with much lower electron temperature, typically 1 ÷ 10 keV. Even these low-energy electrons should be sufficient to excite (either directly or indirectly via bremsstrahlung or characteristic X-ray emission from hot dense plasma) the low-lying nuclear levels. PACS

Active Detectors for Plasma Soft X-Ray Detection at PALS

“…The possibility to excite low-energy nuclear states by laser-induced plasma has been initiated and experimentally investigated [1] on the Prague Asterix Laser System (PALS -see http://www.pals.cas.cz). This medium-energy high-power system yields interaction intensities at the level of 10 16 -10 17 Wcm −2 , which produce subrelativistic plasmas with an electron temperature of the order of 1-10 keV.…”