CMOS vs. CCD sensors in speckle interferometry

In the field of interferometric metrology the use of high resolution CCD sensors with 1024×1024 to 2048×2048 pixels is predominant. Due to special features (e.g. random pixel access, characteristic curve) CMOS sensors with similar resolution can be an interesting alternative. We compare some characteristics of both sensor types that are important for interferometry and demonstrate two exemplary applications that are only possible by using CMOS cameras.     

Charge transfer from the ground state of muonic hydrogen to at room temperature

The present status of research of muon transfer from the ground state of muonic protium to ⁴He is reviewed. The analysis of a recent measurement in a triple gas mixture of H₂+⁴He+Ne at 15 bar and room temperature is presented and the result is compared to the existing experimental and theoretical rates. The average muon transfer rate from protium to ⁴He determined from all lifetime measurements is . Received: 22 January 1998 / Revised: 4 March 1998 / Accepted: 31 March 1998     

Present status of the investigation on muon transfer in gaseous mixtures of hydrogen and oxygen

To investigate the energy dependence of muon transfer to oxygen, we performed measurements in gaseous mixtures of hydrogen and oxygen. The time distributions of the muonic oxygen X-rays showed the same structure as the one observed earlier in H₂+SO₂ mixtures. In the delayed part of these distributions, one can distinguish a short-time and a long-time component. From the latter, we deduced the transfer rates from thermalized muonic protium, respectively deuterium, to oxygen. The short-time component can be interpreted as being due to muon transfer from epithermal muonic hydrogen atoms. The time parameters are characteristic for the deceleration process as well as for energy-dependent transfer rates. With results of recent research on the formation and the thermalization of muonic hydrogen, we performed Monte Carlo simulations in order to test the hypothesis of an energy-dependent transfer rate.     

Untersuchung der Fette

Ohne Zusammenfassung     

Atomic capture ratios of negative muons in gaseous mixtures of hydrogen,nitrogen, neon and argon

The yields of muonic x rays of the Lyman series of nitrogen, neon and argon have been analysed to determine capture ratios A(Z₁,Z₂) in about thirty gaseous mixtures under different experimental conditions. In addition, capture ratios A(Z,H) have been determined in hydrogen mixtures by taking into account transfer processes from muonic hydrogen to elements Z. The influence of the spectral flux density of the muons on capture ratios has been analysed. Our per-atom ratios form a coherent set and confirm the value A(Ar,Ne) = 1. 262(10).     

On orthogonal double covers of kn and a conjecture of chung and west

A collection ?? = {G₁, G₂,…,G_n} of spanning subgraphs of K_n is called an orthogonal double cover if (i) every edge of K_n belongs to exactly two of the G_i's and (ii) any two distinct G_i's intersect in exactly one edge. Chung and West conjectured that there exists an orthogonal double cover of K_n, for all n, in which each G_i has maximum degree 2, and proved this result for n in six of the residue classes modulo 12. In another context, Ganter and Gronau showed that for n ≡ 1 mod 3, n ≠ 10, there exists an orthogonal double cover of K_n in which each G_i consists of an isolated vertex and the vertex disjoint union of K₃'s (actually these orthogonal double covers result from the solution of the directed version of the problem, which reduces to the undirected case when the orientation of the arcs is ignored). Clearly the covers of Ganter and Gronau satisfy the Chung-West requirement. In this article, the configurations of Ganter and Gronau are generalized to include the cases n ≡ 0,2 mod 3, and the results are used to provide a unified solution of the Chung-West problem. For n ≠ 5 mod 6, all the spanning subgraphs in the collection ?? are isomorphic to each other; however, this is not the case when n ≡ 5 mod 6. In addition to solving the Chung-West problem, we also go on to show that for n ≡ 2 mod 3 and n > 287, there exists an orthogonal double cover of K_n in which each spanning subgraph G_i consists of the vertex-disjoint union of an isolated vertex, and quadrilateral, and (n?5)/3 triangles. Of the 96 cases with 2 ? n ? 287, 65 cases are resolved and 31 remain open. © 1995 John Wiley & Sons, Inc.     

Nuclear excitation and prompt fission in muonic238U

A study of muonic²³⁸U has been performed in a combined (μ ^?,γ f) and (μ ^?,γγ) coincidence experiment to investigate the role of non-radiative transitions and their fission probabilities. An augmentation of the outer fission barrier ofΔE _b =(0.6±0.1) MeV due to the presence of the muon is deduced. A significant contribution to the prompt fission yield not only results from the (2p→1s) and (3d→1s) non-radiative transitions, but also from other radiationless transitions. Specifically, the measured fission probabilities of the transitions (2p→1s), (3d→1s), and (3p→1s) are (1.5±0.4)%, (5.7±1.7)%, and (5.3±1.9)%, respectively.     

Recent experiments on muon transfer in gas mixtures

The experimental muon transfer rates from muonic protium and deuterium to heavier elements show a complexZ dependence. Instead of the expected monotonicZ dependence considerable variations between neighboring elements are observed. Transfer to neon has a specially small rate. Furthermore, the time distribution of the muonic X-rays shows in a number of molecules a complex structure, and depends in the case of a H₂ + CH₄ gas mixture also on the total pressure.