The high granularity timing detector(HGTD)is a crucial component of the ATLAS phase Ⅱ upgrade to cope with the extremely high pile-up(the average number of interactions per bunch crossing can be as high as 200).With the precise timing information(σt～30 ps)of the tracks,the track-to-vertex association can be performed in the"4-D"space.The Low Gain Avalanche Detector(LGAD)technology is chosen for the sensors,which can provide the required timing resolution and good signal-to-noise ratio.Hamamatsu Photonics K.K.(HPK)has produced the LGAD with thicknesses of 35 pm and 50 pm.The University of Science and Technology of China(USTC)has also developed and produced 50 pm LGADs prototypes with the Institute of Microelectronics(IME)of Chinese Academy of Sciences.To evaluate the irradi-ation hardness,the sensors are irradiated with the neutron at the JSI reactor facility and tested at USTC.The irradiation ef-fects on both the gain layer and the bulk are characterized by I-V and C-Vmeasurements at room temperature(20℃)or-30℃.The breakdown voltages and depletion voltages are extracted and presented as a function of the fluences.The fi-nal fitting of the acceptor removal model yielded the c-factor of 3.06×10-16 cm-2,3.89×10-16 cm-2 and 4.12×10-16 cm-2 for the HPK-1.2,HPK-3.2 and USTC-1.1-W8,respectively,showing that the HPK-1.2 sensors have the most irradiation resistant gain layer.A novel analysis method is used to further exploit the data to get the relationship between the c-factor and ini-tial doping density.

Xiao Yang;Kuo Ma;Xiangxuan Zheng;Yanwen Liu

Department of Modern Physics,University of Science and Technology of China,Hefei 230026,China;State Key Laboratory of Particle Detection and Electronics,University of Science and Technology of China,Hefei 230026,China

中国科学技术大学学报

[1]Xiao Yang;Kuo Ma;Xiangxuan Zheng;Yanwen Liu-.Radiation hardness characterization of low gain avalanche detector prototypes for the high granularity timing detector)[J].中国科学技术大学学报,2022(01):20-26

HGTD,LGAD,Hamamatsu,HPK,LGADs,Microelectronics,Vmeasurements

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