Performance of the continuous ions suppression TPC prorotype for circular collider

Abstract

The circumference of CEPC (Circular Electron Positron Collider) is 100 km, with two interaction points available for exploring different detector design scenarios and technologies. Two common RF stations are deployed for the Higgs operation, which result in 286 beam bunches evenly distributed over a half ring. While for W and Z operations, independent RF cavities are used, 5220 and 10900 bunches are spreading in equal distance over the full ring, respectively. Therefore, the bunch spacing are about 500 ns, 50 ns and 30 ns for Higgs, W and Z operations, respectively. Aimed to the CDR (Concept Design Report) and TDR (Technical Design Report) of the CEPC project, the feasibility study of TPC (Time Projection Chamber) tracker detector was initiated for the purpose to identify feasible technology options and to gain expertise to build the detector units which meet the basic requirements of the CEPC detector design. The TPC detector at the proposed circular collider will have to be operated continuously and the backflow of ions (IBF (Ions Back Flow)) must be minimized without the open/close time of a gating device technology. The gain of the selection detector module can be achieved up to about 5000 without any obvious discharge behaviour. The currents on the anode and drift cathode were measured precisely with an electrometer. The experimental results showed that IBF can be reduced to less than 0.1% at the specific gain. All update IBF results have been measured using 266 nm UV (Ultra Violet) light, 55Fe and X-ray tube. The future R&D has been mentioned to meet the high luminosity at Z.