Background The Circular Electron-Positron Collider(CEPC)is aimed for precision measurements of the Higgs boson properties and the electroweak parameters.The achievable precision will be largely dependent on the contro...Background The Circular Electron-Positron Collider(CEPC)is aimed for precision measurements of the Higgs boson properties and the electroweak parameters.The achievable precision will be largely dependent on the controlled level of radiation backgrounds,which requires an optimized design of the interaction region to assure the optimal performance of both the accelerator and the detectors.Purpose In this article,the latest results on the radiation backgrounds are reported based on the accelerator parameters and the detector design presented in the CEPC conceptual design reports.Method For the different sources of radiation backgrounds,simulation steps consisting of generation,tracking,and detector simulation were performed.Radiation backgrounds from the processes of synchrotron radiation,pair production,radiative Bhabha scattering,beam gas Bremsstrahlung scattering,and beam thermal photon scattering were considered for the accel-erator operating at the different centre-of-mass energies(HZ threshold,WW threshold,and Z pole).Possible mitigation methods of masks and/or collimators were introduced to suppress the radiation backgrounds,together with the careful opti-mization of the interaction region design.With the improved tracking methods during simulation,the accuracy and reliability of the results were improved.In addition,the radiation backgrounds on the CEPC vertex detector were estimated,and the pair-production was found to be the most important source.Result In the worst case of operation at the Z pole,the vertex detector would have to withstand a total ionization dose of 5.6 Mrad per year and a non-ionization energy loss(shown in 1 MeV neutron equivalent)of 1.06×10^(13)n_(eq)/cm^(2)per year.展开更多
2D position sensitive, single-sided Si stripixel detector was selected as the one of the two main components of the Si vertex tracker (Si SVX) in the upgraded PHENIX detector at RHIC (relativistic heavy ion collider) ...2D position sensitive, single-sided Si stripixel detector was selected as the one of the two main components of the Si vertex tracker (Si SVX) in the upgraded PHENIX detector at RHIC (relativistic heavy ion collider) in Brookhaven National Laboratory (BNL). This is the first large scale application of the novel Si stripixel detector in a real large experiment after many years of research and development at BNL. The first and second prototype fabrication runs of the SVX stripixel detectors were carried out successfully in BNL’s Si detector development and processing Lab. The processing of these stripixel detectors is similar to that for the standard single-sided strip detectors: one-sided processing, single implant for the pixel (strip) electrodes, etc. The only additional processing step is the double metal process, a technology that is simple and well matured by many Si detector processing industries and labs, including BNL. The laser and beam tests on those prototype detectors show the 2D position sensitivity and good position resolution in both X and U coordinates (about 25 μm for 80 μm pitch). For the mass production of 400 sensors needed for the Si SVX, the processing technology has been successfully transferred to the industrial: Hamamatsu Photonics (HPK). HPK has produced a pre-production run of stripixel sensors with the full PHENIX SVX specification on 150 mm diameter wafers. The laser tests on these pre-production wafers show good signal to noise ratio (about 20∶1).展开更多
We describe the algorithm to reconstruct the charged tracks for BESⅢ main drift chamber at BEPCⅡ, including the track finding and fitting. With a new method of the Track Segment Finder （TSF）, the results of presen...We describe the algorithm to reconstruct the charged tracks for BESⅢ main drift chamber at BEPCⅡ, including the track finding and fitting. With a new method of the Track Segment Finder （TSF）, the results of present study indicate that the algorithm can reconstruct the charged tracks over a wide range of momentum with high efficiency, while improving the robustness against the background noise in the drift chamber. The overall performances, including spatial resolution, momentum resolution and secondary vertices reconstruction efficiency, etc. satisfy the requirements of BESⅢ experiment.展开更多
文摘Background The Circular Electron-Positron Collider(CEPC)is aimed for precision measurements of the Higgs boson properties and the electroweak parameters.The achievable precision will be largely dependent on the controlled level of radiation backgrounds,which requires an optimized design of the interaction region to assure the optimal performance of both the accelerator and the detectors.Purpose In this article,the latest results on the radiation backgrounds are reported based on the accelerator parameters and the detector design presented in the CEPC conceptual design reports.Method For the different sources of radiation backgrounds,simulation steps consisting of generation,tracking,and detector simulation were performed.Radiation backgrounds from the processes of synchrotron radiation,pair production,radiative Bhabha scattering,beam gas Bremsstrahlung scattering,and beam thermal photon scattering were considered for the accel-erator operating at the different centre-of-mass energies(HZ threshold,WW threshold,and Z pole).Possible mitigation methods of masks and/or collimators were introduced to suppress the radiation backgrounds,together with the careful opti-mization of the interaction region design.With the improved tracking methods during simulation,the accuracy and reliability of the results were improved.In addition,the radiation backgrounds on the CEPC vertex detector were estimated,and the pair-production was found to be the most important source.Result In the worst case of operation at the Z pole,the vertex detector would have to withstand a total ionization dose of 5.6 Mrad per year and a non-ionization energy loss(shown in 1 MeV neutron equivalent)of 1.06×10^(13)n_(eq)/cm^(2)per year.
基金Project(DE-Ac02-98CH10886) supported in part by the US Department of Energy
文摘2D position sensitive, single-sided Si stripixel detector was selected as the one of the two main components of the Si vertex tracker (Si SVX) in the upgraded PHENIX detector at RHIC (relativistic heavy ion collider) in Brookhaven National Laboratory (BNL). This is the first large scale application of the novel Si stripixel detector in a real large experiment after many years of research and development at BNL. The first and second prototype fabrication runs of the SVX stripixel detectors were carried out successfully in BNL’s Si detector development and processing Lab. The processing of these stripixel detectors is similar to that for the standard single-sided strip detectors: one-sided processing, single implant for the pixel (strip) electrodes, etc. The only additional processing step is the double metal process, a technology that is simple and well matured by many Si detector processing industries and labs, including BNL. The laser and beam tests on those prototype detectors show the 2D position sensitivity and good position resolution in both X and U coordinates (about 25 μm for 80 μm pitch). For the mass production of 400 sensors needed for the Si SVX, the processing technology has been successfully transferred to the industrial: Hamamatsu Photonics (HPK). HPK has produced a pre-production run of stripixel sensors with the full PHENIX SVX specification on 150 mm diameter wafers. The laser tests on these pre-production wafers show good signal to noise ratio (about 20∶1).
基金Supported by CAS Knowledge Innovation Project(U-602,U-34)National Natural Science Foundation of China(10491300,10491303,10605030)100 Talents Program of CAS(U-25,U-54)
文摘We describe the algorithm to reconstruct the charged tracks for BESⅢ main drift chamber at BEPCⅡ, including the track finding and fitting. With a new method of the Track Segment Finder （TSF）, the results of present study indicate that the algorithm can reconstruct the charged tracks over a wide range of momentum with high efficiency, while improving the robustness against the background noise in the drift chamber. The overall performances, including spatial resolution, momentum resolution and secondary vertices reconstruction efficiency, etc. satisfy the requirements of BESⅢ experiment.
