arXiv subjects

Varlen Grabski

Publications and source records attributed to Varlen Grabski.

6 recordsLinked to original sources

arXiv2026

Design and performance of a large-area scintillator-based chamber for the MID subsystem of ALICE 3

This paper reports on the design and construction of a chamber for the muon identifier detector (MID) of the ALICE 3 upgrade project. The chamber consists of two sensitive layers separated by a 1 cm air gap. Each layer holds 24 scintillator bars ($1\times4\times100$ cm$^3$) manufactured by FNAL-NICADD. The bars are equipped with Kuraray wavelength shifting fibers and the readout is provided by a silicon photomultiplier from Hamamatsu. The bars in the second layer are orthogonal to the bars in the first layer, thus providing an overlapping cell size of 4$\times$4 cm$^{2}$. The bar assembly as well as the design of the mechanical structure is described. The design of the chamber is close to that considered in the ALICE 3 letter of intent. The chamber was tested at the CERN T10 beamline using 3 GeV/$c$ pion-enriched and muon beams. The chamber was placed behind an iron absorber, with different absorber lengths considered in the test. The muon identification is performed using a Machine Learning algorithm, which was trained and tested using muon (signal) and pion (background) data (50% of the available statistics). The trained ML algorithm was applied to muon data, yielding a muon efficiency above 99% for the OR condition (detection in either layer 1 or 2). The implementation in the pion-beam data gives the fake-muon efficiency as a function of the absorber length that is well described by an exponential function with a slope parameter of 18.79 cm. The next steps towards finalizing the optimization are outlined.

physics.ins-det↗

arXiv2025

ML-based muon identification using a FNAL-NICADD scintillator chamber for the MID subsystem of ALICE 3

The ALICE Collaboration is planning to construct a new detector (ALICE 3) aiming at exploiting the potential of the high-luminosity Large Hadron Collider (LHC). The new detector will allow ALICE to participate in LHC Run 5 scheduled from 2036 to 2041. The muon-identifier subsystem (MID) is part of the ALICE 3 reference detector layout. The MID will consist of a standard magnetic iron absorber ($\approx4$ nuclear interaction lengths) followed by muon chambers. The baseline option for the MID chambers considers plastic scintillation bars equipped with wave-length shifting fibers and readout with silicon photomultipliers. This paper reports on the performance of a MID chamber prototype using 3 GeV/$c$ pion- and muon-enriched beams delivered by the CERN Proton Synchrotron (PS). The prototype was built using extruded plastic scintillator produced by FNAL-NICADD (Fermi National Accelerator Laboratory - Northern Illinois Center for Accelerator and Detector Development). The prototype was experimentally evaluated using varying absorber thicknesses (60, 70, 80, 90, and 100 cm) to assess its performance. The analysis was performed using Machine Learning techniques and the performance was validated with GEANT 4 simulations. Potential improvements in both hardware and data analysis are discussed.

physics.ins-det↗

arXiv2024

New fiber read-out design for the large area scintillator detectors: providing good amplitude and time resolutions

Most of the time-of-flight systems as well as the fast interaction trigger detectors have large surfaces and the principal requirements for the above mentioned detectors is a good time resolution of the order 100-200ps. The easiest solution here is to split the large surface into the small tiles with a read-out directly attached to the photo-sensor. This solution is expensive because the number of the channels grows proportional to the surface. Although if the coverage of the whole surface by the sensors is not sufficient, one can obtain non uniform response, which is not acceptable if uniformity is required. Our suggestion is based on the usage of clear fibres mounted perpendicular on the surface of the scintillator as a matrix providing uniform surface reduction and keeping most of the benefices of the small tiles with the photo-sensors. In this work the design and some analytic estimations of the light collection efficiency for direct and reflected photons will be presented. Also some simple estimations are presented for the time-spread and for the light pulse wave form dependent on the lateral sizes and the thickness of the scintillator.

physics.ins-det↗

arXiv2018

Deuteron and Antideuteron Production Simulation in Cosmic-ray Interactions

The study of the cosmic-ray deuteron and antideuteron flux receives an increasing interest in current astrophysics investigations. For both cases an important contribution is expected from the nuclear interactions of primary cosmic rays with intergalactic matter. In this work, deuteron and antideuteron production from 20 to 2.6$\times$10$^{7}$ GeV beam energy in p+p and p+A collisions were simulated using EPOS-LHC and Geant4's FTFP-BERT Monte Carlo models by adding an event-by-event coalescence model afterburner. These estimates depend on a single parameter ($p_0$) obtained from a fit to the data. The $p_0$ for deuterons in this wide energy range was evaluated for the first time. It was found that $p_0$ for antideuterons is not a constant at all energies as previous works suggested and as a consequence the antideuteron production cross section can be at least 20 times smaller in the low collision energy region, than earlier estimations.

astro-ph.HE↗

arXiv2009

Performance of the first prototype of the HAWC Gamma Ray Observatory

The HAWC gamma ray observatory, to be constructed at Sierra Negra, Puebla in Mexico, is a large array of water Cherenkov detectors sited at an elevation of 4100 m, which has been optimized for gamma/hadron discrimination of the primary cosmic rays in the TeV energy range. It is based on the Milagro experience, but the design has been changed from a water pond to individual water tanks. In order to validate the design with large water tanks a prototype array has been constructed near the HAWC site with 3 of the largest commercial rotomolded plastic tanks available in Mexico. They have been instrumented with 20 cm hemispherical photomultiplier tubes and read out with 2 Gsample/s flash ADCs. The performance of a single tank has been measured as well as the response of the array to cosmic ray showers. In this paper we present the first measurements of the performance of the HAWC prototype array.

astro-ph.IM↗

arXiv2004

The influence of scattered photons on the accurate determination of microcalcification thickness in digital mammography

Our interest has been to study the effect that scattered radiation has on contrast, signal-to-noise ratio and thickness reconstruction in digital mammographies. Using the GEANT code we have performed Monte-Carlo simulations of 25 kVp Mo/Mo photons, through a breast phantom which contains a 0.2-1.0 mm thick microcalcifications incident on a 20x106 $mm^{2}$ pixelized detector. The data have been analyzed assuming 6 different shapes of the incident beam: a 0.2x0.2 $mm^{2}$ ``narrow'' beam, 4 different 20 mm long scanning beams of various widths, and a 20x100 $mm^{2}$ beam with no scatter reduction mechanisms (NSR) . Since the image of a point depends on scattered photons which passed up to 2 cm away from the object (for 4 cm thick phantom), we identify the background definition as a main source of systematic uncertainty in the image quality analysis. We propose the use of two dimensional functions (a polynomial for the background and Gaussians for the signal) for total photon transmission description. Our main results indicate the possible calcification thickness reconstruction with an accuracy of the order of 6% using 3 mm wide scanning beam. Signal-to-noise ratio with the 3 mm wide beam gets improved by 20% with respect to NSR, a figure similar to that obtained with the narrow beam. Thickness reconstruction is shown to be an alternative to signal-to-noise ratio for microcalcification detection.

physics.med-ph↗