Development of a very low energy μ+ beam at PSI

At PSI we are investigating the technique of decelerating an existing very intense secondary beam of surface ⁺ (4 MeV) to an energy of 10 eV using appropriate moderators. These ⁺ can then be used as a source of a tertiary beam of low energy muons with tunable kinetic energy between 10 eV and 10 keV.With a 1000 A layer of solid Argon deposited on an Al substrate we obtain a moderation efficiency (with respect to the number of incoming surface ⁺) of the order of 10^–4.Results of our investigations and the present status of the project are presented together with future plans and possibilities.     

Development of a beam of very slow polarized muons

During the last few decades, a variety of methods has been developed which makes use of polarized positive muons as a microscopic probe of the magnetic properties of condensed matter (muon spin rotation, relaxation, resonance,SR). Until now, available beams for SR studies have delivered 100% polarized muons with energies in the MeV range, resulting in a deep penetration of the muons into the sample material under investigation. This presently limits the applications of theSR technique to the study of the bulk characteristics of matter. To be able to control the implantation depth, a very low energy beam of polarized muons is being developed at the Paul Scherrer Institute. Very slow polarized muons (kinetic energy 10 eV, polarization 90%) are obtained from the moderation of a high energy muon beam in a thin film of an appropriate condensed gas. These muons can be used as a source for a beam of tunable energy between a few tens of eV and some tens of keV. Implantation depths in the range of few to a few hundreds of nanometers can thus be achieved by varying the energy.     

Identitäten und das Radikal in Jordan-Tripelsystemen

Ohne Zusammenfassung     

Generation of very slow polarized muons by moderation

At the Paul Scherrer Institute very slow, nearly 100% polarized, positive muons with an energy of \sim\mbox10 eV are produced by moderating a secondary beam of surface muons in a thin film of an appropriate condensed gases. These epithermal muons can be used as a source of a tertiary beam of tunable energy between \sim\mbox10 eV and \sim\mbox20 keV. Such a beam allows the μSR technique to be extended to the study of thin films and surfaces. In order to be able to perform time differential μSR experiments we have developed an ultra‐thin detector that registers the passage of keV muons and permits to trigger the experiment. The results achieved so far demonstrate that first investigations of thin film samples can be performed with the present set‐up. This revised version was published online in August 2006 with corrections to the Cover Date.     

Track formulas and derivations in simple jordan pairs

In finite dimensional Lie algebras, Jordan algebras, and other algebraic structures the study of derivations has been facilitated by having a nontrivial trace formula on hand (see for example [?]) . Tuere is no common pattern in proving these trace formulas, they all depend on the underlying structures. In this note we derive such a trace formula for finite dimensional central simple Jordan pairs. We use it to determine all derivations the Killing form and the dimensions of the derivation algebras of the Jordan pairs. Dur primary tool is a Trace Reduction Formula.     

Neutral mass-selected lead cluster beams

Neutral lead cluster beams with ultra-narrow size distribution were produced by neutralization of mass-selected lead cluster ions, Pb _n ⁺ withn≤12, in sodium vapor under near-resonant conditions. Absolute charge exchange cross sections were measured as a function of cluster size and are on the order of 40 Ų forn≥4. Possible fragmentation of the clusters associated with charge transfer was examined by translational spectroscopy. No indication of fragmentation was found.     

Über die Killing-Form in Jordan-Algebren

Ohne Zusammenfassung