This paper shows the simulation and test results of 50 μm thick Low Gain Avalanche Detectors (LGAD) sensors designed by the Institute of High Energy Physics (IHEP) and fabricated by the Institute of ...Microelectronics of the Chinese Academy of Sciences (IME). Three wafers have been produced with four different gain layer implant doses each. Different production processes, including variation in the n++ layer implant energy and carbon co-implantation were used. Test results show that the IHEP-IME sensors with the higher dose of gain layer have lower breakdown voltages and higher gain layer voltages from capacitance–voltage properties, which are consistent with the TCAD simulation. Beta test results show that the time resolution of IHEP-IME sensors is better than 35 ps when operated at high voltage and the collected charges of IHEP-IME sensors are larger than 15 fC before irradiation, which fulfill the required specifications of sensors before irradiations for the ATLAS HGTD project.
Design and testing of LGAD sensor with shallow carbon implantation Wu, Kewei; Jia, Xuewei; Yang, Tao ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2023, Volume:
1046
Journal Article
Peer reviewed
Open access
The low gain avalanche detectors (LGADs) are thin sensors with fast charge collection which in combination with internal gain deliver an outstanding time resolution of about 30 ps for Minimum ...Ionizing Particles (MIP). High collision rates and consequent large particle rates crossing the detectors at the upgraded Large Hadron Collider (LHC) in 2028 will lead to radiation damage and deteriorated performance of the LGADs. The main consequence of radiation damage is loss of gain layer doping (acceptor removal) which requires an increase of bias voltage to compensate for the loss of charge collection efficiency and consequently time resolution. The Institute of High Energy Physics (IHEP), Chinese Academy of Sciences (CAS) has developed a process based on the Institute of Microelectronics (IME), CAS capability to enrich the gain layer with carbon to reduce the acceptor removal effect by radiation. After 1 MeV neutron equivalent fluence of 2.5 × 1015 neq/cm2, which is the maximum fluence to which sensors will be exposed at ATLAS High Granularity Timing Detector (HGTD), the IHEP-IME second version (IHEP-IMEv2) 50μm LGAD sensors already deliver adequate charge collection >4 fC and time resolution <50 ps at voltages <400 V. The operation voltages of these 50μm devices are well below those at which single event burnout may occur.
Gain dependence on free carrier concentration in LGADs Kramberger, G.; Hiti, B.; Cindro, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
01/2023, Volume:
1046
Journal Article
Peer reviewed
Open access
Low gain avalanche detectors (LGADs) were investigated with transient current technique utilizing 1064 nm light to determine the effect of ionization density on the measured gain. The ionization ...density was varied with laser intensity and width of the beam spot. A model was derived explaining the decrease of gain due to the polarization of the gain layer, which reduces the electric field. The model was also tested at different ionization densities for LGADs of different gain layer design.
The Low Gain Avalanche Detector (LGAD) is a novel Silicon detector with precise timing and fast response. To study the transient response of LGADs, we need to obtain the detector signal using ...Transient Current Technique (TCT), for which a preamplifier with high bandwidth and low noise is required. Currently, the most widely used preamplifier board in the LGAD community is developed by University of California, Santa Cruz (UCSC). In this paper, we will introduce a newly designed LGAD preamplifier board. Compared with the UCSC board, the performance has been fully improved. The board contains a transimpedance amplifier and two-stage voltage amplifiers. The total charge gain of our preamplifier reaches 20.58 mV ns/fC, with good linearity in the input dynamic range of 0.7 fC, 66 fC. The −3-dB bandwidth is about 870 MHz, meeting the demands of LGAD amplification. We conducted 90Sr β-scope tests using our preamplifiers and HPK 3.1 single sensors. The equivalent noise charge at 20 °C is 0.27 fC. The jitter contributed by our preamplifier is about 7.12 ps. The results show that our single-channel preamplifier has lower noise and better time resolution than the UCSC boards. Besides, a 9-channel preamplifier board is developed for multi-pad LGAD readout. All channels have good uniformity and low noise. Our preamplifier boards can be well applied in β-scope or laser-scanning TCT tests of LGADs.
Studies of inter-pad distance in Low Gain Avalanche Detectors Skomina, P.; Hiti, B.; Cindro, V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2022, Volume:
1027
Journal Article
Peer reviewed
The effective inter-pad distance of low gain avalanche detector prototypes for ATLAS-HGTD from two producers were investigated. The dependence of the effective inter-pad distance on bias voltage and ...fluence was systematically measured with Transient Current Technique using different laser wavelengths. Bending of the electric field lines at the edges of the electrodes was found to be the reason for the difference between measured and nominal inter-pad distances. The effective inter-pad distances were also simulated and compared to the measurements.
Recent advances in segmented low‐gain avalanche detectors (LGADs) make them promising for the position‐sensitive detection of low‐energy X‐ray photons thanks to their internal gain. LGAD microstrip ...sensors fabricated by Fondazione Bruno Kessler have been investigated using X‐rays with both charge‐integrating and single‐photon‐counting readout chips developed at the Paul Scherrer Institut. In this work it is shown that the charge multiplication occurring in the sensor allows the detection of X‐rays with improved signal‐to‐noise ratio in comparison with standard silicon sensors. The application in the tender X‐ray energy range is demonstrated by the detection of the sulfur Kα and Kβ lines (2.3 and 2.46 keV) in an energy‐dispersive fluorescence spectrometer at the Swiss Light Source. Although further improvements in the segmentation and in the quantum efficiency at low energy are still necessary, this work paves the way for the development of single‐photon‐counting detectors in the soft X‐ray energy range.
Low‐gain avalanche detectors have been characterized using X‐rays. Preliminary tests show promising results towards the development of soft X‐ray single‐photon‐counting detectors.
Experimental Study of Acceptor Removal in UFSD Jin, Y.; Ren, H.; Christie, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2020, Volume:
983, Issue:
C
Journal Article
Peer reviewed
Open access
The performance of the Ultra-Fast Silicon Detectors (UFSD) after irradiation with neutrons and protons is compromised by the removal of acceptors in the thin layer below the junction responsible for ...the gain. This effect is tested both with capacitance–voltage, C–V, measurements of the doping concentration and with measurements of charge collection, CC, using charged particles. We find a perfect linear correlation between the bias voltage to deplete the gain layer determined with C–V and the bias voltage to collect a defined charge, measured with charge collection. An example for the usefulness of this correlation is presented.
Abstract
Single-photon Avalanche Detectors (SPAD) are widely used in modern quantum optics experiments and applications. This work proposes an alternative method for calibrating SPADs by optical ...attenuation, based on the recognition of the statistical distribution of time intervals between consecutive detections.
Development of the CMS MIP timing detector Lucchini, Marco
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2020, Volume:
958
Journal Article
Peer reviewed
Open access
The CMS detector at the CERN Large Hadron Collider is undergoing an extensive Phase II upgrade programme to prepare for the challenging conditions of the High-Luminosity LHC. In particular, a new ...timing detector, the MTD, will measure minimum ionizing particles with a time resolution of 30–50 ps and hermetic coverage up to a pseudo-rapidity of |η|=3. The MTD will consist of a central barrel region based on L(Y)SO:Ce crystals read out with SiPMs and two end-caps instrumented with radiation-tolerant low gain avalanche detectors. The precision time information from the MTD will reduce the effects of the high levels of pile-up expected at the High-Luminosity LHC and will bring new and unique capabilities to the CMS detector. The time information assigned to each track will enable the use of 4D reconstruction algorithms and will further discriminate interaction vertices within the same bunch crossing to recover the track purity of vertices in current LHC conditions. We present the motivations for precision timing at the High-Luminosity LHC, the overall detector design and technological choices including ongoing R&D studies targeting enhanced timing performance and radiation tolerance.
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