460 research outputs found
Low gain avalanche diodes for photon science applications
No full textLow Gain Avalanche Diodes (LGADs) are silicon sensors designed to achieve an internal gain in the order of 10 through the impact ionization process. The development of LGADs was pushed forward by their application in High Energy Physics (HEP) experiments, where they will be employed to provide measurements of the time of arrival of minimum ionizing particles with a resolution of around 30 ps. The initial technological implementation of the sensors constrains their minimum channel size to be larger than 1 mm2, in order to reduce inefficiencies due to the segmentation of the gain structure. The gain of the sensors is kept in the order of 10 to limit the sensor shot noise and their power consumption. In photon science, the gain provided by the sensor can boost the signal-to-noise ratio of the detector system, effectively reducing the x-ray energy threshold of photon counting detectors and the minimum x-ray energy where single photon resolution is achieved in charge integrating detectors. This can improve the hybrid pixel and strip detectors for soft and tender x-rays by simply changing the sensor element of the detector system. Photon science applications in the soft and tender energy range require improvements over the LGADs developed for HEP, in particular the presence of a thin entrance window to provide a satisfactory quantum efficiency and channel size with a pitch of less than 100 μm. In this review, the fundamental aspects of the LGAD technology are presented, discussing also the ongoing and future developments that are of interest for photon science applications
Neutron irradiation effect on SiPMs up to = 5 10 cm
No full textSilicon Photo-Multipliers (SiPM) are becoming the photo-detector of choice for increasingly more particle detection applications, from fundamental physics, to medical and societal applications. One major consideration for their use at high-luminosity colliders is the radiation damage induced by hadrons, which leads to a dramatic increase of the dark count rate. KETEK SiPMs have been exposed to various fluences of reactor neutrons up to Φneq = 5 × 10 14 cm −2 (1 MeV equivalent neutrons). Results from the I–V, and C–V measurements for temperatures between − 30 °C and +30 °C are presented. We propose a new method to quantify the effect of radiation damage on the SiPM performance. Using the measured dark current the single pixel occupation probability as a function of temperature and excess voltage is determined. From the pixel occupation probability the operating conditions for given requirements can be optimized. The method is qualitatively verified using current measurements with the SiPM illuminated by blue LED light.Silicon Photo-Multipliers (SiPM) are becoming the photo-detector of choice for increasingly more particle detection applications, from fundamental physics to medical and societal applications. One major consideration for their use at high-luminosity colliders is the radiation damage induced by hadrons, which leads to a dramatic increase of the dark count rate. KETEK SiPMs have been exposed to various fluences of reactor neutrons up to = 510 cm (1 MeV equivalent neutrons). Results from the I-V, and C-V measurements for temperatures between 30C and 30C are presented. We propose a new method to quantify the effect of radiation damage on the SiPM performance. Using the measured dark current the single pixel occupation probability as a function of temperature and excess voltage is determined. From the pixel occupation probability the operating conditions for given requirements can be optimized. The method is qualitatively verified using current measurements with the SiPM illuminated by blue LED light
Neutron induced radiation damage of KETEK SiPMs
No full textSilicon photomultipliers (SiPMs), thanks to their excellent performance, are becoming the photodetectors of choice for many applications. One major limitation, in particular for their use at high-luminosity colliders, is the radiation damage by hadrons. In this work, SiPMs with 4384 pixels of 15 × 15 μm 2 size produced by KETEK have been irradiated by reactor neutrons to six fluences up to Φ eq = 10 12 cm -2 (1 MeV equivalent neutrons). Pulse-height, IV, and CV measurements with and without illumination by a LED for temperatures between -30 and 30° C have been performed. In this paper results from the IV, and CV measurements are shown. The fluence and the temperature dependence of the current and of the SiPM electrical parameters like pixel capacitance, quenching resistance and breakdown voltage allows to better understand the origin of the dark current and find ways to reduce the radiation-induced dark-count-rate
Characterisation of irradiated thin silicon sensors for the CMS phase II pixel upgrade
No full textThe high luminosity upgrade of the Large Hadron Collider, foreseen for 2026, necessitates the replacement of the CMS experiment’s silicon tracker. The innermost layer of the new pixel detector will be exposed to severe radiation, corresponding to a 1 MeV neutron equivalent fluence of up to Φeq=2×1016 cm−2, and an ionising dose of ≈5 MGy after an integrated luminosity of 3000 fb−1. Thin, planar silicon sensors are good candidates for this application, since the degradation of the signal produced by traversing particles is less severe than for thicker devices. In this paper, the results obtained from the characterisation of 100 and 200 μm thick p-bulk pad diodes and strip sensors irradiated up to fluences of Φeq=1.3×1016 cm−2 are shown
Status of the 3D Silicon Detectors activities at FBK
No full textIn the talk, ongoing activities on 3D processes will be presented. FBK is actively involved in the realization of detectors with RD53 and CROC designs for both ATLAS and CMS experiments. The latest developments and parametric measurements with Temporary Metal for these processes will be discussed. Additionally, FBK is continuing the development of 3D sensors based on trenches. Due to their geometry, these sensors are considered candidates for achieving excellent temporal resolutions along with high damage resistance. In the AIDA Innova project, FBK is producing a batch, and the main characteristics of this batch will be highlighted
A Comprehensive Characterization of the TI-LGAD Technology
No full textPixelated low-gain avalanche diodes (LGADs) can provide both precision spatial and temporal measurements for charged particle detection; however, electrical termination between the pixels yields a no-gain region, such that the active area or fill factor is not sufficient for small pixel sizes. Trench-isolated LGADs (TI-LGADs) are a strong candidate for solving the fill-factor problem, as the p-stop termination structure is replaced by isolated trenches etched in the silicon itself. In the TI-LGAD process, the p-stop termination structure, typical of LGADs, is replaced by isolating trenches etched in the silicon itself. This modification substantially reduces the size of the no-gain region, thus enabling the implementation of small pixels with an adequate fill factor value. In this article, a systematic characterization of the TI-RD50 production, the first of its kind entirely dedicated to the TI-LGAD technology, is presented. Designs are ranked according to their measured inter-pixel distance, and the time resolution is compared against the regular LGAD technology
Characterization of novel trench-isolated LGADs for 4D tracking
No full textIn recent years, Low Gain Avalanche Detectors (LGADs) have shown the capability of timing measurements in the tens of ps range for minimum ionizing particles. However, the segmentation of LGADs creates regions with no gain and provides a hindrance in achieving 100% fill factor (FF) for many applications and using LGADs as 4-dimensional (4D) tracking devices. The new LGAD design based on the trench isolation technique (TI-LGAD) is very promising in reducing the no-gain region and hence increased FF which in turn makes them capable of 4D tracking. This paper describes the features of a new TI-LGAD sensors production by FBK, in which the no-gain region is reduced significantly by replacing Junction Termination Extension (JTE) and p-stop implant with slender trenches. A new R&D batch is produced in FBK within the RD50 collaboration, in which several border layouts and fabrication processes are implemented. The new TI-LGAD batch enables a systematic study to select the best fabrication process and border layout. In this paper, the electrical and laser characterization, isolation between pixels, and the results on the measurement of no-gain region between pixels are presented
Jitter Measurements of 1 cm2 LGADs for Space Experiments
No full textThis work explores the possibility of using Low Gain Avalanche Diodes (LGADs) for tracker-based experiments studying Charged Cosmic Rays (CCRs) in space. While conventional silicon microstrip sensors provide only spatial information about the charged particle passing through the tracker, LGADs have the potential to provide additional timing information with a resolution in the order of tens of picoseconds. For the first time, it has been demonstrated that an LGAD with an active area of approximately 1 cm2 can achieve a jitter of less than 40 ps. A comparison of design and gain layers is carried out to understand which provides the best time resolution. For this purpose, laboratory measurements of sensors’ electrical properties and gain using LED and an Infrared laser, as well as their jitter, were performed
Radiation Tolerance of Proton-Irradiated LGADs
No full textLow gain avalanche detectors (LGADs), silicon sensors with intrinsic charge amplification, are being considered as a possible technology for tracking and timing in the high luminosity upgrade of the CERN Large Hadron Collider. In order to work in such an environment, LGADs must be sufficiently radiation hard. The characterisation before and after irradiation of properties, such as gain, charge collection, spatial homogeneity, space charge, and leakage current, is vital for assessing the performance and viability of LGADs. This paper presents the results obtained from the study of LGADs irradiated with 24-GeV/c protons up to a maximum fluence of 10 15 neq/cm 2 . The characterisation was performed mainly by means of the transient current technique with red and infrared laser pulses. It was found that the gain decreases with increasing fluence. At a fluence of 10 15 neq/cm 2 , the charge collected is similar to that of a normal p-i-n diode. Whilst this might be explained by an effective acceptor removal, it was also found that there are clear signs of a double junction in these devices, after irradiation. In addition, the spatial charge collection homogeneity before and after irradiation was evaluated
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