arXiv subjects

A. Lozar

Publications and source records attributed to A. Lozar.

4 recordsLinked to original sources

arXiv2025

Aerogel RICH Counter at the Belle II Detector

We report on the design, operation, and performance of a novel proximity-focusing Ring Imaging Cherenkov (RICH) detector equipped with a multilayer focusing aerogel radiator, developed for the forward region of the Belle II spectrometer at the SuperKEKB $e^+e^-$ collider. The system achieves effective separation of charged pions, kaons, and protons across the full kinematic range of the experiment, from 0.5 GeV/c to 4 GeV/c. To date, the detector has successfully operated in data-taking, contributing to the collection and analysis of nearly 600/fb of Belle II $e^+e^-$ collision data.

hep-ex↗

arXiv2025

Characterisation of the LAPPD, a large area microchannel-plate PMT

We present a comprehensive characterization of the LAPPD Gen-II, a large-area microchannel-plate photomultiplier tube (MCP-PMT) equipped with a capacitively coupled sensing (readout) electrode. Two detector variants with different geometries and materials were investigated using a picosecond pulsed laser system. We measured the single-photon timing response and spatial charge distribution on segmented readout electrodes. The prompt timing peak exhibits a resolution of approximately 30 ps, with the overall timing structure explained by photoelectron propagation and back-scattering effects from the MCP input surface. We developed analytical models that describe the propagation of photoelectrons and the induced charge spread on the sensing electrodes, including secondary electron backscattering from the resistive anode. The model accurately reproduces the measured device properties and enables performance extrapolations for various detector geometries and dielectric properties. These results provide a predictive framework for optimizing MCP-PMTs for timing- and imaging-critical applications such as RICH detectors in high-energy physics and TOF-PET systems for medical imaging.

physics.ins-det↗

arXiv2023

LAPPD operation using ToFPETv2 PETSYS ASIC

Single photon sensitive detectors used in high energy physics are, in some applications, required to cover areas the size of several m2, and more specifically in very strong demand with15 an ever finer imaging and timing capability for Cherenkov Ring Imaging Detector (RICH) configurations. We are evaluating the Large Area Picosecond Photo-detector (LAPPD) produced by INCOM company, as a possible candidate for future RICH detector upgrades. In this work we perform tests on the second generation device, which is capacitively coupled to a custom designed anode back plane, consisting of various pixels and strips varying in size, that allows for connecting various readout systems such as standard laboratory equipment, as well as the TOFPET2 ASIC from PETsys company. Our aim is to evaluate what can be achieved by merging currently available technology, in order to find directions for future developments adapted for specific uses.

physics.ins-det↗

arXiv2020

Intermodular Configuration Scrubbing of On-detector FPGAs for the ARICH at Belle II

On-detector digital electronics in High-Energy Physics experiments is increasingly being implemented by means of SRAM-based FPGA, due to their capabilities of reconfiguration, real-time processing and multi-gigabit data transfer. Radiation-induced single event upsets in the configuration hinder the correct operation, since they may alter the programmed routing paths and logic functions. In most trigger and data acquisition systems, data from several front-end modules are concentrated into a single board, which then transmits data to back-end electronics for acquisition and triggering. Since the front-end modules are identical, they host identical FPGAs, which are programmed with the same bitstream. In this work, we present a novel scrubber capable of correcting radiation-induced soft-errors in the configuration of SRAM-based FPGAs by majority voting across different modules. We show an application of this system to the read-out electronics of the Aerogel Ring Imaging CHerenkov (ARICH) subdetector of the Belle2 experiment at SuperKEKB of the KEK laboratory (Tsukuba, Japan). We discuss the architecture of the system and its implementation in a Virtex-5 LX50T FPGA, in the concentrator board, for correcting the configuration of up to six Spartan-6 LX45 FPGAs, on pertaining front-end modules. We discuss results from fault-injection and neutron irradiation tests at the TRIGA reactor of the Jozef Stefan Institute (Ljubljana, Slovenia) and we compare the performance of our solution to the Xilinx Soft Error Mitigation controller.

physics.ins-det↗