R&D of a high-performance DIRC detector for a future electron-ion collider

Abstract

An Electron-Ion Collider (EIC) is proposed as the next big scientific facility to be built in the United States, costing over $1 billion in design and construction. Each detector concept for the electron/ion beam interaction point is integrated into a large solenoidal magnet. The necessity for excellent hadronic particle identification (pion/kaon/proton) in the barrel region of the solenoid has pushed research and development (R&D) towards a new, high-performance Detection of Internally Reflected Cherenkov light (DIRC) detector design. The passage of a high energy charged particle through a fused silica bar of the DIRC generates optical Cherenkov radiation. A large fraction of this light propagates by total internal reflection to the end of the bar, where the photon trajectories expand in a large volume before reaching a highly segmented photo-detector array. The spatial and temporal distribution of the Cherenkov light at the photo-detector array allows one to reconstruct the angle of emission of the light relative to the incident charged particle track. In order to reach the desired performance of 3σ π/K separation at 6 GeV/c particle momentum a new 3-layer spherical lens focusing optic with a lanthanum crown glass central layer was designed to have a nearly flat focal plane. In order to validate the EIC DIRC simulation package, a synergistic test beam campaign was carried out in 2015 at the CERN PS with the PANDA Barrel DIRC group using a prototype DIRC detector. Along with the analysis of the CERN test beam data, measurements of the focal plane of the 3-layer lens were performed using a custom-built laser setup at Old Dominion University. Radiation hardness of the lanthanum crown glass was tested using a 160 keV X-ray source and a monochromator at the Catholic University of America. Results of these test-bench experiments and the analysis of the 2015 CERN test beam data are presented here.iii

Novel support for membrane enzyme immobilization: gel beads containing polymerized phospholipid vesicles

“…The more complicated rate equation for p-nitroaniline liberation by the entire set of γ-GT reactions has been obtained in the same manner [19]. In the present study, however, only apparent parameters were obtained by taking the reaction as a Michaelis-Menten reaction for simplicity to compare the reactivities of γ-GT immobilized in beads through different types of vesicle.…”

“…The kinetic mechanism for γ-GT has been studied by many workers [19]. Because autotranspeptidation (in which the donor substrate acts as an acceptor) is negligible in this assay, the γ-GT reaction inside the beads is expressed by a modified Ping Pong kinetic mechanism [19].…”

“…The kinetic mechanism for γ-GT has been studied by many workers [19]. Because autotranspeptidation (in which the donor substrate acts as an acceptor) is negligible in this assay, the γ-GT reaction inside the beads is expressed by a modified Ping Pong kinetic mechanism [19]. That is, first the γ-glutamyl donor (L-γ-glutamyl-p-nitroanilide) binds the enzyme and a γ-glutamyl-enzyme intermediate forms to release the first product (p-nitroaniline); the acceptor (glycylglycine) then binds to the intermediate, and transfer of the γ-glutamyl moiety proceeds.…”