We present cross section experimental data required for modeling beam production, attenuation and energy loss in the heavy-ion beam probe technique, namely, electron-loss cross sections for anionic gold projectiles and Ar and N 2 targets in the energy range from 30 keV to 1 MeV. The results agree well with low-energy measured values from the literature for the Ar target. The present results are also compared with literature results for the H − projectile and the Ar target, displaying similar velocity dependences. This similarity led to the use of a simple semi-classical model to calculate the projectile-electron-loss cross sections in a wide energy range. This model employs the total scattering cross sections for free electrons and the momentum distribution of the Au − electrons. The present experimental results are in good agreement with this model, allowing a reliable estimate of the cross section values up to 100 MeV. Our results indicate that previously calculated cross sections are overestimated by at least a factor of two. This previous overestimation of electron-loss cross sections leads to significant errors in the modeling of charge-state fractions of gold beams, with consequences in the optimization of beam energy resolution and intensity for HIBP with megaelectronvolts gold beams.

The electron-detachment cross section was measured for the molecular negative ions CN − and O − 2 incident on N 2 , in the 0.08-1.2 a.u. velocity region. Our setup uses the gas stripper of a tandem accelerator as a gas chamber. All cross sections present a maximum near 0.4 a.u., a velocity corresponding to the well-known shape-resonance that appears in the electron-N 2 collisions. A semiclassical model is employed to analyze the data. The role of this shape resonance is discussed in this article.

We increase the versatility of a tandem electrostatic accelerator by implementing simple modifications to the standard operation procedure. While keeping its ability to deliver MeV ion beams, we show that the experimental setup can (i) provide good quality ion beams in the few-keV energy range and (ii) be used to study ion-beam surface modification with simultaneous secondary ion mass spectrometry. This latter task is accomplished without using any chamber connected to the accelerator exit. We perform mass spectrometry of the few-keV anions produced in the ion source by measuring their neutral counterparts at the accelerator exit with energies up to 1.7 MeV. With an additional modification, a high-current few-keV regime is obtained, using the ion source as an irradiation chamber and the accelerator itself only as a mass spectrometer. As an example of application, we prepare a sample for the study of ion-beam assisted dewetting of a thin Au film on a Si substrate.

In this work, we present lifetime measurements of nS states of Rb as a function of the principal quantum number (40 n 70) using a sample of cold atoms held in a magneto-optical trap, which is performed in a finite size metal vacuum chamber. The Rydberg states are excited through a two-photon transition, and detected by pulsed field ionization. Our measurements are larger than the predictions by well established theoretical model (1984 Phys. Rev. A 30 2881 and 2009 Phys. Rev. A 79 052504). We have implemented a theoretical model, which considers the vacuum chamber as a lossy Fabry–Perot cavity with a discrete spectrum, and compared with experimental results. Such comparison indicates that the blackbody radiation contribution on Rydberg state lifetime can be decreased by using a small size metal cavity, without the need of cryogenic environment. This effect may have application in experiments where longer Rydberg lifetimes are required.