Developed In The Relativistic Heavy Ion Experiments Of Mrpc / Tof

Relativistic Heavy Ion Physics has always been one of the most forward nature study of the world. Global features of our Universe and the origin of mass are believed to be linked to the phase transitions of matter. At extremely high temperature or density, the nuclear matter will transit into Quark-Gluon Plasma (QGP) state. This transition took place some 10^-5s after the Big Bang in the early universe in an inverse direction. To study the physics of Quark-Gluon Plasma needs large hadronic colliders of extremely high energy. The constructions of the Relativistic Heavy Ion collider (RHIC) at Brookhaven National Laboratory (BNL) and the Large Hadron Collider (LHC) at CERN provide powerful tools for the study of the ultra-relativistic heavy-ion physics. They are expected to reach or even exceed the critical energy density (ε_c¹GeVfm^-3 corresponding to a temperature of ¹70MeV) predicted by the theoretical models. Thus one can check the existing particle physics models and develop new physics theories.In these relativistic heavy ion collisions, mass final state particles will be produced which makes great challenge to the particle identification of the detectors. A Time-Of-Flight (TOF) detector will be used both on RHIC/STAR and LHC/ALICE to enhance the particle identification capability with the measured flight time and also the momentum information measured by other sub-detectors. As a detector for the TOF measurement, it should have a good intrinsic time resolution and a high detection efficiency of all; it should also endure the high flux of particles produced in the collisions without any loss in performance. A traditional solution is based on the fast scintillators and good photomultiplier tubes (PMT). The high multiplicity of the ultra-relativistic heavy-ion collisions requires a high granularity of the detector and a lot of electronics channels. The PMTs can work under the high magnetic field of the detector region are extremely expensive. The total cost will be extremely high for the large number of detection channels. All these facts indicate that the scintillators + PMT solution is impossible. To fulfill the particle identification requirement in heavy ion collisions, a lot of study has been taken to make a new type of detector with high time resolution at acceptable price. Some new ideas and methods have been considered. The introduction of gaseous detectors into this area offers a new access to develop such a TOF detector and opens a new area for the use of the gaseous detectors. A new kind Multi-gap Resistive Plate Chamber (MRPC) with internal plates electrically floating makes it possible to construct such a high time resolution TOF system.For a gaseous detector with parallel plate structure, the reduction of the gas gap size can reduce the time jitter related to the position of the primary ionization, thus the time resolution is enhanced. Some kinds of gaseous detectors have been considered such as the Microgap Chamber (MGC), the Resistive Plate Chamber (RPC), et al. But with the smaller gap size, the number of primary ionization and the distance that the electrons drift through are reduced. This leads to a reduction of the induced charge. For the large area RPCs working under proportional mode,...