Between September 2006 and September 2007, 236 samples of raw (n=140), pasteurized (n=48) and UHT (n=48) milk were collected from supermarkets and from bulk milk tanks of eight dairy plants in the cities of Esfahan and Shahr-e Kord, Iran. All samples were analyzed for aflatoxin M 1 (AFM 1 ) contamination by ELISA and 213 (90.3%) were positive with mean concentrations 65 ng.l −1 . These concentrations are lower than the standards of Codex Alimentarius and FDA (500 ng.l −1 ), but 119 samples (55.9%) had higher concentrations than the maximum tolerance accepted by some European countries (50 ng.l −1 ). Mean concentrations of AFM 1 in raw, pasteurized and UHT milk were 68, 56, and 65 ng.l −1 , respectively. Mean concentrations of AFM 1 in autumn and winter samples were significantly higher (P<0.05) than those of spring and summer but differences between AFM 1 concentrations of spring and summer samples were not significantly different.Concentrations of AFM 1 in milk from Shahr-e Kord were significantly lower (P≤0.05) than those from Esfahan.

The magnetic moment (g-factor) of the electron is a fundamental quantity in physics that can be measured with high accuracy by spectroscopy in Penning traps. Its value has been predicted by theory, both for the case of the free (unbound) electron and for the electron bound in a highly charged ion. Precision measurements of the electron magnetic moment yield a stringent test of these predictions and can in turn be used for a determination of fundamental constants such as the fine structure constant or the atomic mass of the electron. For the bound-electron magnetic-moment measurement, two complementary approaches exist, one via the so-called "continuous Stern-Gerlach effect", applied to ions with zero-spin nuclei, and one a spectroscopic approach, applied to ions with nonzero nuclear spin. Here, the latter approach is detailed, and an overview of the experiment and its status is given.

No abstract

We have performed a detailed experimental study of resistive cooling of large ensembles of highly charged ions such as Ar 13+ in a cryogenic Penning trap. Different from the measurements reported in [M. Vogel et al., Phys. Rev. A 90, 043412 (2014)], we observe purely exponential cooling behavior when conditions are chosen to allow collisional thermalization of the ions. We provide evidence that in this situation, resistive cooling time constants and final temperatures are independent of the initial ion energy, and that the cooling time constant of a thermalized ion ensemble is identical to the single-ion cooling time constant. For sufficiently high ion number densities, our measurements show discontinuities in the spectra of motional resonances which indicate a transition of the ion ensemble to a fluid-like state when cooled to temperatures below approximately 14 K. With the final ion temperature presently being 7.5 K, ions of the highest charge states are expected to form ion crystals by mere resistive cooling, in particular not requiring the use of laser cooling. arXiv:1809.08606v1 [physics.atom-ph]

We have conceived, built, and operated a cryogenic Penning trap with an electrically conducting yet optically transparent solid electrode. The trap, dedicated to spectroscopy and imaging of confined particles under large solid angles is of 'half-open' design with one open endcap and one closed endcap that mainly consists of a glass window coated with a highly transparent conductive layer. This arrangement allows for trapping of externally or internally produced particles, yields flexible access for optical excitation and efficient light collection from the trapping region. At the same time, it is electrically closed and ensures long-term ion confinement under well-defined conditions. With its superior surface quality and its high as well as homogeneous optical transmission, the window electrode is an excellent replacement for partially transmissive electrodes that use holes, slits, metallic meshes and the like.