R. Van de Vyver

The HERMES dual-radiator ring imaging Cherenkov detector

Abstract The construction and use of a dual radiator Ring Imaging Cherenkov (RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasises measurements of semi-inclusive deep-inelastic scattering. It provides particle identification for pions, kaons, and protons in the momentum range from 2 to 15 GeV , which is essential to these studies. The instrument uses two radiators, C 4 F 10 , a heavy fluorocarbon gas, and a wall of silica aerogel tiles. The use of aerogel in a RICH detector has only recently become possible with the development of clear, large, homogeneous and hydrophobic aerogel. A lightweight mirror was constructed using a newly perfected technique to make resin-coated carbon-fiber surfaces of optical quality. The photon detector consists of 1934 photomultiplier tubes (PMT) for each detector half, held in a soft steel matrix to provide shielding against the residual field of the main spectrometer magnet.

First measurement of the Gerasimov-Drell-Hearn integral for Hydrogen from 200 to 800 MeV

A direct measurement of the helicity dependence of the total photoabsorption cross section on the proton was carried out at MAMI (Mainz) in the energy range 200<E_gamma<800 MeV. The experiment used a 4

Helicity dependence of the gamma p -> N pi channels and multipole analysis in the Delta region

\pi

First determination of generalized polarizabilities of the proton by a virtual compton scattering experiment.

detection system, a circularly polarized tagged photon beam and a frozen spin target. The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward spin polarizability

A general solid angle calculation by a Monte Carlo method

\gamma_0

Helicity dependence of the reaction in the second resonance region

determined from the data are 226 \pm 5 (stat)\pm 12(sys) \mu b and -187 \pm 8 (stat)\pm 10(sys)10^{-6} fm^4, respectively, for 200<E_\gamma<800 MeV.

The forward, backward and 90° deuteron photodisintegration between 7 and 19 MeV photon energy

Abstract.A high-quality double-polarization data set for the helicity dependence of the total and differential cross-sections for both

The GDH-Detector

\gamma p\rightarrow N \pi

Total photoneutron cross sections for 12C and 19F

channels in the

A new measurement of the structure functions PLL - PTT/ε and PLT in virtual Compton scattering at Q2 = 0.33 (GeV/c)2

\Delta