Ionization of Rydberg atoms by blackbody radiation

We have studied an ionization of alkali-metal Rydberg atoms by blackbody radiation (BBR). The results of the theoretical calculations of ionization rates of Li, Na, K, Rb and Cs Rydberg atoms are presented. Calculations have been performed for nS, nP and nD states which are commonly used in a variety of experiments, at principal quantum numbers n=8-65 and at the three ambient temperatures of 77, 300 and 600 K. A peculiarity of our calculations is that we take into account the contributions of BBR-induced redistribution of population between Rydberg states prior to photoionization and field ionization by extraction electric field pulses. The obtained results show that these phenomena affect both the magnitude of measured ionization rates and shapes of their dependences on n. A Cooper minimum for BBR-induced transitions between bound Rydberg states of Li has been found. The calculated ionization rates are compared with our earlier measurements of BBR-induced ionization rates of Na nS and nD Rydberg states with n=8-20 at 300 K. A good agreement for all states except nS with n>15 is observed. Useful analytical formulas for quick estimation of BBR ionization rates of Rydberg atoms are presented. Application of BBR-induced ionization signal to measurements of collisional ionization rates is demonstrated.Comment: 36 pages, 16 figures. Paper is revised following NJP referees' comments and suggestion

Study of the d (d, n)

The results of the measurements of the astrophysical S -factor and cross-sections of the reaction dd → ^3He+ n in the deuteron energy collision range of 2.3-6.2keV are presented. The experiment was carried out at the high-current deuteron beam of the Hall pulsed accelerator (FSSI “Nuclear Physics Institute”, Tomsk). Deuterated polyethylene (CD2) targets and frozen heavy water (D2O) were used. Neutrons were detected by eight plastic scintillation counters ( 375×100×100 mm^3) located around the target. The results obtained in the present work substantially differ from the results of the experiments conducted with the use of deuterium saturated metal targets (TiD, TaD, ZrD, PtD). Within statistical errors of measurements there is no discrepancy between the present results and the results of the experiments performed with the heavy-water targets and filled with gaseous-deuterium targets