0000000000281840
AUTHOR
M. Christmann
showing 7 related works from this author
Beam-normal single spin asymmetry in elastic electron scattering off 28Si and 90Zr
2020
We report on a new measurement of the beam-normal single spin asymmetry $A_{\mathrm{n}}$ in the elastic scattering of 570 MeV transversely polarized electrons off $^{28}$Si and $^{90}$Zr at $Q^{2}=0.04\, \mathrm{GeV}^2/c^2$. The studied kinematics allow for a comprehensive comparison with former results on $^{12}$C. No significant mass dependence of the beam-normal single spin asymmetry is observed in the mass regime from $^{12}$C to $^{90}$Zr.
Tubulointerstitielle-Nephritis-Uveitis-Syndrom (TINU-Syndrom)
1995
Abstract For 10 weeks a 25-year-old man had been suffering from tiredness, fatigue, nausea and a 16 kg weight loss. Erythrocyte sedimentation rate (83/133 mm), serum C-reactive protein (5.5 mg/dl) and creatinine (5.05 mg/dl) were all elevated. He also had proteinuria (1120 mg daily), sterile leukocytosis and a creatinine clearance of 10 ml/min. Renal biopsy showed interstitial nephritis and bone marrow biopsy revealed non-caseous epithelioid-cell granulomas. 14 days after admission he developed acute iritis in the right eye. Other causes having been excluded, the diagnosis of tubulo-intestinal nephritis with uveitis (TINU syndrome) was made. The clinical symptoms and laboratory findings imp…
Detector response of Cherenkov radiators for calorimetry in the energy range below 14 MeV
2020
Abstract A study of the detector response of PbF 2 crystals and three different types of lead glass blocks to electrons from a 14-MeV beam of the Mainz Microtron MAMI is presented. For the first time, signal height, signal width, and homogeneity of the response of these Cherenkov radiators were determined for energies between 10 and 14 MeV. To complement the beam tests, optical properties of the materials, in particular measured transmittances in the near UV and visible spectrum, were studied. The measured detector responses were also compared to Monte Carlo simulations of energy-loss, light production, transport, and detection. These Cherenkov radiators are considered as active material o…
Electron beam studies of light collection in a scintillating counter with embedded fibers
2021
The light collection of several fiber configurations embedded in a box-shaped plastic scintillating counter was studied by scanning with minimum ionizing electrons. The light was read out by silicon photomultipliers at both ends. The light yield produced by the 855-MeV beam of the Mainz Microtron showed a strong dependence on the transverse distance from the beam position to the fibers. The observations were modeled by attributing the collection of indirect light inside of the counter and of direct light reaching a fiber to the total light yield. The light collection with fibers was compared to that of a scintillating counter without fibers. These studies were carried out within the develop…
Operation and characterization of a windowless gas jet target in high-intensity electron beams
2021
Abstract A cryogenic supersonic gas jet target was developed for the MAGIX experiment at the high-intensity electron accelerator MESA. It will be operated as an internal, windowless target in the energy-recovering recirculation arc of the accelerator with different target gases, e.g., hydrogen, deuterium , helium, oxygen, argon, or xenon. Detailed studies have been carried out at the existing A1 multi-spectrometer facility at the electron accelerator MAMI. This paper focuses on the developed handling procedures and diagnostic tools, and on the performance of the gas jet target under beam conditions. Considering the special features of this type of target, it proves to be well suited for a n…
Instrumentation and optimization studies for a beam dump experiment (BDX) at MESA — DarkMESA
2020
Abstract At the Institute for Nuclear Physics in Mainz the new electron accelerator MESA will go into operation within the next years. The high-power beam dump of the P2 experiment is ideally suited for a parasitic dark sector experiment — DarkMESA. In the first stage 1,000 high density Cherenkov radiators from a previous experiment will be used. The experiment is studied with a simulation based on MadGraph and Geant4 . The simulation includes an optical photon study, where the response of possible calorimeter materials – PbF 2, BGO, the Pb glasses SF5, SF6 and SF57HTultra from Schott – was investigated. The simulation outcomes are compared with the results of prototypes tested at the Mainz…
Beam-normal single spin asymmetry in elastic electron scattering off Si and Zr
2020
We report on a new measurement of the beam-normal single spin asymmetry An in the elastic scattering of 570 MeV transversely polarized electrons off $^{28}$Si and $^{90}$Zr at Q2=0.04 GeV2/c2. The studied kinematics allow for a comprehensive comparison with former results on $^{12}$C. No significant mass dependence of the beam-normal single spin asymmetry is observed in the mass regime from $^{12}$C to $^{90}$Zr.