H. Genz | Searcharxiv

arXiv2000

Latest Developments from the S-DALINAC*

The S-DALINAC is a 130 MeV superconducting recirculating electron accelerator serving several nuclear and radiation physics experiments as well as driving an infrared free-electron laser. A system of normal conducting rf resonators for noninvasive beam position and current measurement was established. For the measurement of gamma-radiation inside the accelerator cave a system of Compton diodes has been developed and tested. Detailed investigations of the transverse phasespace were carried out with a tomographical reconstruction method of optical transition radiation spots. The method can be applied also to non-Gaussian phasespace distributions. The results are in good accordance with simulations. To improve the quality factor of the superconducting 3 GHz cavities, an external 2K testcryostat was commissioned. The influence of electro-chemical polishing and magnetic shielding is currently under investigation. A digital rf-feedback-system for the accelerator cavities is being developed in order to improve the energy spread of the beam of the S-DALINAC. * Supported by the BMBF under contract no. 06 DA 820, the DFG under contract no. Ri 242/12-1 and -2 and the DFG Graduiertenkolleg 'Physik und Technik von Beschleunigern'

physics.acc-ph↗

arXiv1994

Tests of isospin symmetry breaking at $ϕ(1020)$ meson factories

In a model of isospin symmetry breaking we obtain the ($e^{-} e^{+} \rightarrow π^{-} π^{+}$) amplitude $Q$ and the isospin $I=0$ and $I=1$ relative phase $ψ$ at the $ϕ(1020)$ resonance in aproximate agreement with experiment. The model predicts $Γ(ϕ\rightarrow ωπ^{0}) \approx 4 \cdot 10^{-4} \;\mbox{MeV}$. We have also obtained $Γ(ϕ\rightarrow η' γ)=5.2 \cdot 10^{-4} \;\mbox{MeV}$. Measuring this partial width would strongly constrain $η$-$η'$ mixing. The branching ratios $BR$ of the isospin violating decays $ρ^{+} \rightarrow π^{+} η$ and $η' \rightarrow ρ^{\pm} π^{\mp}$ are predicted to be $BR(ρ^{+} \rightarrow π^{+} η)=3 \cdot 10^{-5}$ and $BR(η' \rightarrow ρ^{\pm} π^{\mp})=4 \cdot 10^{-3}$, respectively, leading to $BR[ϕ\rightarrow ρ^{\pm} π^{\mp} \rightarrow (π^{\pm} η)π^{\mp} \rightarrow (π^{\pm} γγ)π^{\mp}]=10^{-6}$ and $BR[ϕ\rightarrow η' γ\rightarrow (ρ^{\pm} π^{\mp})γ]=2\cdot 10^{-6}$.

hep-ph↗