arXiv subjects

Jiri Kroll

Publications and source records attributed to Jiri Kroll.

5 recordsLinked to original sources

arXiv2026

Radiation effects on surface and bulk properties of ATLAS18 silicon sensors under low- and high-dose gamma irradiation and annealing

Silicon strip detectors for the ATLAS Inner Tracker (ITk) at the HL-LHC must withstand harsh radiation conditions, including fluences of up to 1.6E15 1 MeV n$_{eq}$/cm$^{2}$ and total ionizing doses (TID) of up to 66 Mrad. These requirements are met using radiation-hard n+-in-p technology implemented in the ATLAS18 silicon strip sensors currently under production. This work presents a combined study of gamma-irradiation effects in ATLAS18 silicon sensors, including both segmented miniature strip sensors (minis) and unsegmented MD8 diodes fabricated on ATLAS18 production wafers. The samples were irradiated with a $^{60}$Co gamma source to multiple low TIDs between 0.5 and 100 krad, corresponding to the dose range relevant for the early operational phase of the ITk tracker. Additional measurements extending up to a few Mrad were performed to investigate the saturation of surface related damage effects. Post-irradiation characterization included measurements of total, bulk, and surface leakage currents, as well as capacitance-voltage measurements used to extract the full depletion voltage. The thermal stability of radiation-induced defects was studied using isochronal annealing between 80{\deg}C and 300{\deg}C and isothermal annealing at 60{\deg}C and 160{\deg}C. In addition, complementary studies of MD8 diodes irradiated to ultra-high doses of several hundred Mrad, well beyond the ATLAS ITk requirements, are included to investigate possible bulk-related effects induced by pure gamma irradiation and their annealing behavior. The combined analysis of low- and ultra-high-dose irradiation provides a comprehensive picture of surface- and bulk-related gamma-induced effects in ATLAS18 silicon sensors and their thermal evolution.

physics.ins-det↗

arXiv2026

Impact of Cold Noise on the tracking performance of ATLAS ITk short strip barrel modules using a charged particle beam

The inner tracking system of the ATLAS experiment will be upgraded to a full silicon detector in 2030 for HL-LHC. The new tracking system is called ITk, the Inner Tracker. It is required to be operable with efficiency higher than 99\% and noise hit occupancy smaller than 0.1\%. During the pre-production phase of the ITk project, many short-strip modules were observed to exhibit so-called "Cold Noise (CN)", wherein clusters of strips displayed very high noise when the modules were operated at temperatures below~$-35\degree$C. To investigate the CN impact and ensure the quality of module production, huge amount of effort have been put in by the collaboration. This paper focuses on the impact of CN on the tracking performance by examining two short strip modules that exhibit CN: one is non-irradiated, while the other one has been irradiated to the maximum expected end-of-lifetime fluence. For each module, the global and single strip tracking performance are evaluated.

physics.ins-det↗

arXiv2025

Test beam measurements and computer simulations of the ATLAS ITk R2 silicon strip detector

The ATLAS Inner Tracker, the future innermost part of the ATLAS detector, is an all-silicon tracker composed of pixel and strip modules, designed to cope with the extreme conditions expected during High-Luminosity LHC runs. Thorough testing of modules during the individual phases of their development is critical to ensure the required performance level of the whole tracker. This document presents results obtained from electron beam measurements of the ATLAS ITk R2 end-cap strip module. Key performance metrics are presented and discussed for both perpendicular and angled beam incidence. Computer simulations of the module were performed in the Allpix-Squared framework and the results were compared to experimental data.

physics.ins-det↗

arXiv2025

Quality Concerns Caused by Quality Control -- deformation of silicon strip detector modules in thermal cycling tests

The ATLAS experiment at the Large Hadron Collider (LHC) is currently preparing to replace its present Inner Detector (ID) with the upgraded, all-silicon Inner Tracker (ITk) for its High-Luminosity upgrade (HL-LHC). The ITk will consist of a central pixel tracker and the outer strip tracker, consisting of about 19,000 strip detector modules. Each strip module is assembled from up to two sensors, and up to five flexes (depending on its geometry) in a series of gluing, wirebonding and quality control steps. During detector operation, modules will be cooled down to temperatures of about -35C (corresponding to the temperature of the support structures on which they will be mounted) after being initially assembled and stored at room temperature. In order to ensure compatibility with the detector's operating temperature range, modules are subjected to thermal cycling as part of their quality control process. Ten cycles between -35C and +40C are performed for each module, with full electrical characterisation tests at each high and low temperature point. As part of an investigation into the stress experienced by modules during cooling, it was observed that modules generally showed a change in module shape before and after thermal cycling. This paper presents a summary of the discovery and understanding of the observed changes, connecting them with excess module stress, as well as the resulting modifications to the module thermal cycling procedure.

hep-ex↗

arXiv2018

Summary and Conclusions of the First DESY Test Beam User Workshop

On October 5/6, 2017, DESY hosted the first DESY Test Beam User Workshop [1] which took place in Hamburg. Fifty participants from different user communities, ranging from LHC (ALICE, ATLAS, CMS, LHCb) to FAIR (CBM, PANDA), DUNE, Belle-II, future linear colliders (ILC, CLIC) and generic detector R&D presented their experiences with the DESY II Test Beam Facility, their concrete plans for the upcoming years and a first estimate of their needs for beam time in the long-term future beyond 2025. A special focus was also on additional improvements to the facility beyond its current capabilities.

physics.ins-det↗