0000000001320142
AUTHOR
R. Wichmann
Performance of the ATLAS silicon strip detector modules
Abstract The performance of the silicon strip detector prototypes developed for use in ATLAS at the LHC is reported. Baseline detector assemblies (“modules”) of 12 cm length were read out with binary electronics at 40 MHz clock speed. For both irradiated and unirradiated modules, the tracking efficiency, noise occupancy, and position resolution were measured as a function of bias voltage, binary hit threshold, and detector rotation angle in a 1.56 T magnetic field. Measurements were also performed at a particle flux comparable to the one expected at the LHC.
Beam Asymmetry of Coherentπ° Photoproduction on4Hein theΔ(1232) Range Measured using Coherent Bremsstrahlung
Using coherent bremsstrahlung at MAMI (Mainz), the beam asymmetry of the differential cross sections for coherent $\ensuremath{\pi}\ifmmode^\circ\else\textdegree\fi{}$ photoproduction on ${}^{4}\mathrm{He}$ has been measured in the energy interval from 200 to 500 MeV at an angle of ${\ensuremath{\theta}}_{\mathrm{lab}}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}37\ifmmode^\circ\else\textdegree\fi{}$. The coherent ( $\ensuremath{\gamma},\ensuremath{\pi}\ifmmode^\circ\else\textdegree\fi{}$) reaction is used as a precise linear polarimeter for the first time. Agreement with predictions has been obtained on a $\ensuremath{\gtrsim}3%$ level of precision.
Photoemission of protons from4He in theΔ-resonance region
High resolution proton energy spectra from the4He(γ,p) reaction have been measured with tagged photons in the range Eγ = 130−525 MeV using the large Mainz NaI(T1) spectrometer atΘplab=37.1°. Three separate reaction channels were identified, viz.4He(γ,p)t two-body breakup,4He photodisintegration via two-nucleon photon absorption processes and the quasifree pion production channel. Differential cross sections are presented for each of these channels as a function of photon energy. The sum of the two-nucleon photon absorption and the quasifree pion production differential cross sections, in the CM system, resembles that of the corresponding free-nucleon differential cross section when Fermi mo…
Beam test of the ATLAS silicon detector modules
Abstract Results are reported from a beam test of prototype silicon microstrip detectors and front-end electronics developed for use in the LHC detector ATLAS. The detector assemblies (“modules”) were 12 cm long and were read out with binary electronics. Both irradiated and unirradiated modules were measured in a 1.56 T magnetic field for efficiency, noise occupancy, and position resolution as a function of bias voltage, binary hit threshold, and detector rotation angle with respect to the beam direction.
Angular and polarization dependence of Compton scattering from in the Δ-resonance region
Abstract Using linearly polarized tagged photons from coherent bremsstrahlung, differential cross sections and beam asymmetries for Compton scattering by 4 He have been measured at MAMI in the energy interval between 150 MeV and 500 MeV for scattering angles of θ γ lab =37°, 93° and 137°, thus largely increasing the available data base. Improved calculations in terms of the Δ -hole model completely fail to describe the data at large scattering angles. The same proved to be true for a schematic model, even after taking into account properties of nuclear photo-absorption in very detail.
"Table 1" of "Angular and polarization dependence of Compton scattering from He-4 in the Delta resonance region"
Axis error includes +- 0.0/0.0 contribution.