Determination of the solid angle and response function of a hemispherical spectrograph with injection lens for Auger electrons emitted from long lived projectile states.
We present SIMION 8.1 Monte Carlo type simulations of the response function and detection solid angle for long lived Auger states (lifetime τ ∼ 10(-9) - 10(-5) s) recorded by a hemispherical spectrograph with injection lens and position sensitive detector used for high resolution Auger spectroscopy of ion beams. Also included in these simulations for the first time are kinematic effects particular to Auger emission from fast moving projectile ions such as line broadening and solid angle limitations allowing for a more accurate and realistic line shape modeling. Our results are found to be in excellent agreement with measured electron line shapes of both long lived 1s2s2p(4)P and prompt Auger projectile states formed by electron capture in collisions of 25.3 MeV F(7+) with H2 and 12.0 MeV C(4+) with Ne recorded at 0° to the beam direction. These results are important for the accurate evaluation of the 1s2s2p (4)P/(2)P ratio of K-Auger cross sections whose observed non-statistical production by electron capture into He-like ions, recently a field of interesting interpretations, awaits further resolution.
Nonstatistical enhancement of the 1s2s2p 4P state in electron transfer in 0.5-1.0-MeV/u C4,5 +He and Ne collisions
Nonstatistical enhancements for formation of the metastable $1s2s2p\phantom{\rule{0.2em}{0ex}}^{4}P$ state compared to the similarly configured $1s2s2p\phantom{\rule{0.2em}{0ex}}^{2}P_{\ensuremath{-}}$ and $1s2s2p\phantom{\rule{0.2em}{0ex}}^{2}P_{+}$ states are observed following single electron transfer to ${\mathrm{C}}^{4+}(1s2s\phantom{\rule{0.2em}{0ex}}^{3}S)$ and double electron transfer to ${\mathrm{C}}^{5+}(1s)$ ions, respectively. Previously, similar enhancements were observed in the population of the $^{4}P$ metastable state resulting from electron transfer in $\ensuremath{\sim}1\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{u}$ ${\mathrm{F}}^{7,8+}+\mathrm{He}$ and Ne collisions [J. A. Tanis et al., Phys. Rev. Lett. 92, 133201 (2004)]. The enhancements were attributed to a dynamical Pauli exchange mechanism involving projectile and target electrons having the same spin alignment. Recently, it was suggested that the enhancement might be due to cascade effects following electron transfer to states with $ng3$. To further understand the observed enhancement of the $^{4}P$ state, new investigations of Auger emission spectra in collisions of $0.5--1\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}∕\mathrm{u}$ ${\mathrm{C}}^{4,5+}$ with He and Ne targets have been conducted. Experimental ratios of the resulting $^{4}P$ intensities to the sum of the $^{2}P_{\ensuremath{-}}$ and $^{2}P_{+}$ intensities for the collision systems studied give values three to four times larger than expected based solely on spin statistics for single transfer to ${\mathrm{C}}^{4+}(1s2s\phantom{\rule{0.2em}{0ex}}^{3}S)$ and double transfer to ${\mathrm{C}}^{5+}(1s)$. Theoretical calculations suggest that about half of the observed enhancement is caused by cascade effects.
Can Centauros or Chirons BE the First Observations of Evaporating Mini Black Holes
We argue that the signals expected from the evaporation of mini black holes — predicted in TeV-gravity models with large extra dimensions, and possibly produced in ultrahigh energy collisions in the atmosphere — are quite similar to the characteristics of the Centauro events, an old mystery of cosmic-ray physics.