arXiv subjects

E. L. Gkougkousis

Publications and source records attributed to E. L. Gkougkousis.

5 recordsLinked to original sources

arXiv2022

Comprehensive technology study of radiation hard LGADs

Towards radiation tolerant sensors for pico-second timing, several dopants are explored. Using a common mask, CNM produced LGADs with boron, boron + carbon and gallium implanted gain layers are studied under neutron and proton irradiation. With fluences ranging from $10^{14}$ to $6\times 10^{15} n_{eq}/cm^{2}$ on both particle species, reported results focus on acceptor removal and gain reduction via electrical characterization. Timing performance, charge collection, gain and relative efficiency are treated through charged particle measurements, including signal analysis and noise characterization. An accent is placed on stability, via dark rate and operating voltage studies while, radiation related gain reduction mechanisms are examined comparing gain estimations through different approaches.

physics.ins-det↗

arXiv2020

Beam test results of IHEP-NDL Low Gain Avalanche Detectors(LGAD)

To meet the timing resolution requirement of up-coming High Luminosity LHC (HL-LHC), a new detector based on the Low-Gain Avalanche Detector(LGAD), High-Granularity Timing Detector (HGTD), is under intensive research in ATLAS. Two types of IHEP-NDL LGADs(BV60 and BV170) for this update is being developed by Institute of High Energy Physics (IHEP) of Chinese Academic of Sciences (CAS) cooperated with Novel Device Laboratory (NDL) of Beijing Normal University and they are now under detailed study. These detectors are tested with $5GeV$ electron beam at DESY. A SiPM detector is chosen as a reference detector to get the timing resolution of LGADs. The fluctuation of time difference between LGAD and SiPM is extracted by fitting with a Gaussian function. Constant fraction discriminator (CFD) method is used to mitigate the effect of time walk. The timing resolution of $41 \pm 1 ps$ and $63 \pm 1 ps$ are obtained for BV60 and BV170 respectively.

physics.ins-det↗

arXiv2020

Radiation Campaign of HPK Prototype LGAD sensors for the High-Granularity Timing Detector (HGTD)

We report on the results of a radiation campaign with neutrons and protons of Low Gain Avalanche Detectors (LGAD) produced by Hamamatsu (HPK) as prototypes for the High-Granularity Timing Detector (HGTD) in ATLAS. Sensors with an active thickness of 50~$μ$m were irradiated in steps of roughly 2$\times$ up to a fluence of $3\times10^{15}~\mathrm{n_{eq}cm^{-2}}$. As a function of the fluence, the collected charge and time resolution of the irradiated sensors will be reported for operation at $-30^{\circ}$.

physics.ins-det↗

arXiv2020

Layout and Performance of HPK Prototype LGAD Sensors for the High-Granularity Timing Detector

The High-Granularity Timing Detector is a detector proposed for the ATLAS Phase II upgrade. The detector, based on the Low-Gain Avalanche Detector (LGAD) technology will cover the pseudo-rapidity region of $2.4<|η|<4.0$ with two end caps on each side and a total area of 6.4 $m^2$. The timing performance can be improved by implanting an internal gain layer that can produce signal with a fast rising edge, which improve significantly the signal-to-noise ratio. The required average timing resolution per track for a minimum-ionising particle is 30 ps at the start and 50 ps at the end of the HL-LHC operation. This is achieved with several layers of LGAD. The innermost region of the detector would accumulate a 1 MeV-neutron equivalent fluence up to $2.5 \times 10^{15} cm^{-2}$ before being replaced during the scheduled shutdowns. The addition of this new detector is expected to play an important role in the mitigation of high pile-up at the HL-LHC. The layout and performance of the various versions of LGAD prototypes produced by Hamamatsu (HPK) have been studied by the ATLAS Collaboration. The breakdown voltages, depletion voltages, inter-pad gaps, collected charge as well as the time resolution have been measured and the production yield of large size sensors has been evaluated.

physics.ins-det↗

arXiv2018

Beam test measurements of Low Gain Avalanche Detector single pads and arrays for the ATLAS High Granularity Timing Detector

For the high luminosity upgrade of the LHC at CERN, ATLAS is considering the addition of a High Granularity Timing Detector (HGTD) in front of the end cap and forward calorimeters at |z| = 3.5 m and covering the region 2.4 < |η| < 4 to help reducing the effect of pile-up. The chosen sensors are arrays of 50 μm thin Low Gain Avalanche Detectors (LGAD). This paper presents results on single LGAD sensors with a surface area of 1.3x1.3 mm2 and arrays with 2x2 pads with a surface area of 2x2 mm^2 or 3x3 mm^2 each and different implant doses of the p+ multiplication layer. They are obtained from data collected during a beam test campaign in Autumn 2016 with a pion beam of 120 GeV energy at the CERN SPS. In addition to several quantities measured inclusively for each pad, the gain, efficiency and time resolution have been estimated as a function of the position of the incident particle inside the pad by using a beam telescope with a position resolution of few μm. Different methods to measure the time resolution are compared, yielding consistent results. The sensors with a surface area of 1.3x1.3 mm^2 have a time resolution of about 40 ps for a gain of 20 and of about 27 ps for a gain of 50 and fulfill the HGTD requirements. Larger sensors have, as expected, a degraded time resolution. All sensors show very good efficiency and time resolution uniformity.

physics.ins-det↗