A Bi-Dimensional Multi-Wire Cathode Strip Detector for Fission Fragments
A large area bi-dimensional position sensitive multi-wire cathode strip detector (MCSD) has been developed for the detection of fission fragments (FFs). The performance of the detector has been characterized with FFs from 252Cf and α particles from 241Am-239Pu sources. The position information is obtained from the measurement of time delay signals of the cathode strips (X-direction) and split-cathode wires (Y-direction) with respect to the timing signal from the anode wires. The position resolution is found to be about 1.0 and 1.5 mm in X-and Y-directions respectively.
X-ray detectors based on multiwire proportional chambers
The multiwire proportional chamber (MWPC), operating in a direct photon-counting mode, is used as the basis of 1D and 2D X-ray detectors. The 1D detector used in our scanning radiographic systems is serially produced. Its counting rate is about 200 MHz, its spatial resolution 0.6 mm, the number of channels is 640. The 2D detector, designed for diffraction structural researches on synchrotron radiation at the storage ring VEPP-3, is being commissioned now. Its characteristics are: 5 MHz, 1.5 mm, 65536 channels. The second 1D detector (10 MHz, 75 μm, 3300 channels, σ = 150 μm) is made for the same purposes. A third 1D detector with a registration angle of 60° (500 MHz, 0.6 mm, 1900 channels) is under development. All the detectors operate in a frame-by-frame mode and are free (except 2D) of parallax error.
Monte carlo simulation of events with Drell-Yan lepton pairs from antiproton-proton collisions
The complete knowledge of the nucleon spin structure at leading twist requires also addressing the transverse spin distribution of quarks, or transversity, which is yet unexplored because of its chiral-odd nature. Transversity can be best extracted from single-spin asymmetries in fully polarized Drell-Yan processes with antiprotons, where valence contributions are involved anyway. Alternatively, in single-polarized Drell-Yan the transversity happens convoluted with another chiral-odd function, which is likely to be responsible for the well known (and yet unexplained) violation of the Lam-Tung sum rule in the corresponding unpolarized cross section. We present Monte Carlo simulations for the unpolarized and single-polarized Drell-Yan pp{sup ({up_arrow}}{sup )}{yields}{mu}{sup +}{mu}{sup -}X at different center-of-mass energies in both configurations where the antiproton beam hits a fixed proton target or it collides on another proton beam. The goal is to estimate the minimum number of events needed to extract the above chiral-odd distributions from future measurements at the high energy storage ring (HESR) at GSI. It is important to study the feasibility of such experiments at HESR in order to demonstrate that interesting spin physics can be explored already using unpolarized antiprotons.