[en] A Flash-ADC data acquisition (DAQ) system has been developed for the drift chamber array designed for the External-Target-Experiment at the Cooling Storage Ring at the Heavy Ion Research Facility, Lanzhou. The simplified readout electronics system has been developed using the Flash-ADC modules and the whole waveform in the sampling window is obtained, with which the time and energy information can be deduced with an offline processing. A digital filter algorithm has been developed to discriminate the noise and the useful signal. With the digital filtering process, the signal to noise ratio (SNR) is increased and a better time and energy resolution can be obtained. (authors)

[en] Abstract Background: Multi Wire Drift Chamber(MWDC) array is the tracking detector at Cooling storage ring External-target Experiment(CEE) under design at Heavy Ion Research Facility at Lanzhou-Cooling Storage Ring(HIRFL-CSR). The physical goal of CEE aims at the studies of the equation of state of nuclear matter at low temperature but high baryon density. The MWDC array needs a large amount of front end electronics followed by a scalable data acquisition system, which are all costly. Purpose: The aim is to design a readout scheme which can lower the cost but keep the performance of the array rarely degraded, and to test the system and demonstrate the feasibility of the design. Methods: Based on the Flash Analog-to-Digital Converter(ADC) acquisition scheme, a fan-in and delay module has been designed in order to record three signals from X, U and V sense wires simultaneously in each Flash-ADC channel. Results: By this means the total number of channels for MWDC is reduced by 60%. The performance of this fan-in and delay module is tested with a MWDC detector using ⁵⁵Fe X-ray source. The amplitude signal and the timing signal are smeared by less than 1% and 500 ps, respectively. Conclusion: Both specifications show that the fan-in and delay module can be used in MWDC with the event rate ranging in 1-10kHz. (authors)

[en] The building of a large-scale external-target experiment, abbreviated as CEE, in the cooling storage ring at the Heavy Ion Research Facility in Lanzhou has been planned. The CEE is a multi-purpose spectrometer that will be used for various studies on heavy-ion collisions. A multi-wire drift chamber (MWDC) array is the forward tracking detector of the CEE. In this work, GEANT4 simulations were performed for the MWDC forward tracking array with a focus on the track reconstruction algorithm. Combined with the time of flight information, particle identification is achieved. The residue is about 30 μm, while the tracking efficiency is higher than 90% with the current redundancy. In addition, a prototype of the forward tracking system using three MWDCs was assembled and tested using a high-energy proton beam. The firing efficiency of the detector and the reconstruction accuracy of the prototype were derived. The track residue for the protons at about 400 MeV/c is better than 300 μm, meeting the requirements of the CEE. Suggestions for improving the performance of the forward tracking system are given. (authors)

[en] The influences of fly ash and metakaolin added as substitutions (by up to 50 wt%) of magnesium potassium phosphate cement (MKPC) on the microstructures and compressive strengths of the MKPC pastes were investigated. The results indicate that the aluminosilicate fractions of both fly ash and metakaolin are involved in the acid-base reaction of MKPC system, leading to a preferential formation of irregular crystalline struvite-K incorporated with Al and Si elements and/or amorphous aluminosilicate phosphate products. Metakaolin is more reactive than fly ash in the MKPC system. For the same addition dosage, the MKPC pastes containing metakaolin exhibit higher compressive strengths than the pastes containing fly ash. This is attributed to the formation of more highly reinforced microstructures and denser interfaces between the metakaolin particle and hydration products (e.g. struvite-K) in the MKPC paste containing metakaolin. Addition of 30 wt% metakaolin increases the compressive strengths of MKPC pastes at all test ages.