Objective.Monolithic active pixel sensors are used for charged particle tracking in many applications, from medical physics to astrophysics. The Bergen pCT collaboration designed a sampling calorimeter for proton computed tomography, based entirely on the ALICE PIxel DEtector (ALPIDE). The same telescope can be used for in-situ range verification in particle therapy. An accurate charge diffusion model is required to convert the deposited energy from Monte Carlo simulations to a cluster of pixels, and to estimate the deposited energy, given an experimentally observed cluster.Approach.We optimize the parameters of different charge diffusion models to experimental data for both proton computed tomography and proton range verification, collected at the Danish Centre for Particle Therapy. We then evaluate the performance of downstream tasks to investigate the impact of charge diffusion modeling.Main results.We find that it is beneficial to optimize application-specific models, with a power law working best for proton computed tomography, and a model based on a 2D Cauchy-Lorentz distribution giving better agreement for range verification. We further highlight the importance of evaluating the downstream tasks with multiple approaches to obtain a range of expected performance metrics for the application.Significance.This work demonstrates the influence of the charge diffusion model on downstream tasks, and recommends a new model for proton range verification with an ALPIDE-based pixel telescope.

Proton computed tomography (pCT) is an imaging reconstruction technique that uses protons’ positions, directions, and energy loss to generate a map of an object’s relative stopping power. In this work, the trigger-controlling system was designed and constructed to synchronize between components of our proposed pCT prototype and a proton beam at King Chulalongkorn Memorial Hospital (KCMH) in Bangkok. The controlling system can control the proton beam gating, a rotational stage, and ALPIDE sensors, which are parts of a tracker and a proton calorimeter of the pCT prototype. The controlling system was constructed based on the MEGA2560 microcontroller unit. The controlling system was verified by measuring the activated rows of the ALPIDE sensor at different proton extraction times. Additionally, the controlling system can control an array of six ALPIDE sensors, which could provide preliminary results of the proton calorimeter prototype.

This article presesnts the construction and theoretical research of thermal models of electronic modules with increased power based on combined boards on aluminum bases using serial heat-welding polyimide - fluoroplastic films, including films with thermal conductivity from 0.12 to 0.46 W/m•K, as well as with the lacquer foil dielectrics with thermal conductivity of PI layers of the order of 4.0 - 4.5 W/(m•K) improved by the authors Designs and quality test structures of electronic modules were developed. Experimental studies of the efficiency of heat removal from semiconductor devices in quality test structures based on various types of combined boards with polyimide dielectrics were performed. Technical solutions of combined boards based on multi-layer heat-conductive heat-welding PMF film Kapton®120FMT616 30 μm thick with fluoropolymer double-sided coatings with a thermal conductivity of 0.46 W/(m•K) and combined circuit boards based on improved one-sided lacquer foil copper - polyimide dielectrics with a thickness of highly thermally conductive composite PI layers 60 μm with a thermal conductivity of up to 4.0 - 4.5 W/(m•K), provided under favorable operating conditions with natural unobstructed convection and temperature environment Ta = 25oС the best thermal characteristics of electronic modules from the point of view of maintaining recommended operating temperatures < 70 – 80 °C for high reliability of operation and increased service life.

A Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature.

We present the performance of a full-length prototype of the ALICE Forward Calorimeter (FoCal). The detector is composed of a silicon-tungsten electromagnetic sampling calorimeter with longitudinal and transverse segmentation (FoCal-E) of about 20 X 0 and a hadronic copper-scintillating-fiber calorimeter (FoCal-H) of about 5 λ int . The data were taken in various test beam campaigns between 2021 and 2023 at the CERN PS and SPS beam lines with hadron beams up to energies of 350 GeV, and electron beams up to 300 GeV. Regarding FoCal-E, we report a comprehensive analysis of its response to minimum ionizing particles across all pad layers, employing various operational modes including different pre-amplifier and bias voltage settings. The longitudinal shower profile of electromagnetic showers is measured with a layer-wise segmentation of 1 X 0 . As a projection to the performance of the final detector in electromagnetic showers, we demonstrate linearity in the full energy range, and show that the energy resolution fulfills the requirements for the physics needs. Additionally, the performance to separate two-showers events was studied by quantifying the transverse shower width. Regarding FoCal-H, we report a detailed analysis of the response to hadron beams between 60 and 350 GeV. The results are compared to simulations obtained with a Geant4 model of the test beam setup, which in particular for FoCal-E are in good agreement with the data. The energy resolution of FoCal-E was found to be lower than 3% at energies larger than 100 GeV. The response of FoCal-H to hadron beams was found to be linear, albeit with a significant intercept that is about factor 2 larger than in simulations. Its resolution, which is non-Gaussian and generally larger than in simulations, was quantified using the FWHM, and decreases from about 16% at 100 GeV to about 11% at 350 GeV. The discrepancy to simulations, which is particularly evident at low hadron energies, needs to be further investigated.

Heat-conductive properties of thin heat-conductive polyimide dielectrics have been studied and their thermal resistances have been calculated. Possibility of creating combined printed circuit boards on heat-conductive bases with reduced thermal resistances of polyimide dielectrics from ~ 0.2 to ~ 0.04 °С /W is confirmed. Design parameters and thermal properties of the combined boards with thin polyimide (PI) dielectrics for receivers of concentrated solar radiation are studied. Possibility of providing thermal resistances of PI dielectrics not exceeding 0.43 °С/W has been confirmed. Technical solutions of volumetric light-emitting diode (LED) modules on combined heat-conductive boards, which are 3D-holders-heat sinks, made in the form of single heat-conductive light-reflecting mirrored element, are studied. High thermal characteristics of the modules were achieved due to increase in the area of heat sink holders by more than 2.5 – 3 times compared to flat-type LED modules. Scientific and technical sources were analyzed for selection of modern polyimide materials intended for development and manufacture of combined boards on heat-conductive bases with dielectrics made of polyimide films with increased thermal conductivity up to 0.36 – 0.75 W/(m•K). Potential possibility of creating effective combined printed circuit boards on heat-conductive basis, including those that can be bent, is confirmed using modern industrially manufactured thin heat-conductive PI films with heat-sealable thermoplastic coatings that provide the value of total thermal resistance of boards from 1.5 up to 2.8 °C•cm2/W.

The Bergen proton Computed Tomography (pCT) is a prototype detector under con-struction. It aims to have the capability to track and measure ions' energy deposition to minimize uncertainty in proton treatment planning. It is a high granularity digital tracking calorimeter, where the first two layers will act as tracking layers to obtain positional information of the incoming parti-cle. The remainder of the detector will act as a calorimeter. Beam tests have been performed with multiple beams. These tests have shown that the ALPIDE chip sensor can measure the deposited energy, making it possible for the sensors to distinguish between the tracks in the Digital Tracking Calorimeter (DTC).

Objective. Gradient-based optimization using algorithmic derivatives can be a useful technique to improve engineering designs with respect to a computer-implemented objective function. Likewise, uncertainty quantification through computer simulations can be carried out by means of derivatives of the computer simulation. However, the effectiveness of these techniques depends on how ‘well-linearizable’ the software is. In this study, we assess how promising derivative information of a typical proton computed tomography (pCT) scan computer simulation is for the aforementioned applications. Approach. This study is mainly based on numerical experiments, in which we repeatedly evaluate three representative computational steps with perturbed input values. We support our observations with a review of the algorithmic steps and arithmetic operations performed by the software, using debugging techniques. Main results. The model-based iterative reconstruction (MBIR) subprocedure (at the end of the software pipeline) and the Monte Carlo (MC) simulation (at the beginning) were piecewise differentiable. However, the observed high density and magnitude of jumps was likely to preclude most meaningful uses of the derivatives. Jumps in the MBIR function arose from the discrete computation of the set of voxels intersected by a proton path, and could be reduced in magnitude by a ‘fuzzy voxels’ approach. The investigated jumps in the MC function arose from local changes in the control flow that affected the amount of consumed random numbers. The tracking algorithm solves an inherently non-differentiable problem. Significance. Besides the technical challenges of merely applying AD to existing software projects, the MC and MBIR codes must be adapted to compute smoother functions. For the MBIR code, we presented one possible approach for this while for the MC code, this will be subject to further research. For the tracking subprocedure, further research on surrogate models is necessary.

New approaches to manufacturing improved combined boards on aluminum bases with various thin polyimide dielectrics, including thermally conductive ones, foiled by copper or aluminum foil have been proposed. Design and technological solutions and methods for manufacturing combined printed circuit boards on aluminum bases using industrial thin thermally conductive polyimide dielectric films with fluoropolymer coatings with thermal conductivity from 0,12 to 0,46 W/(m·K) have been developed. Design and technological solutions and methods for manufacturing combined printed circuit boards on thermally conductive aluminum bases using adhesive-free copper-polyimide and aluminum-polyimide lacquer foil dielectrics with thermal conductivity of varnish polyimide layers from 0,12 up to 1,0 W/(m·K) and more have been developed. Main chemical, mechanical, electrical end thermal properties of various types of experimental combined printed circuit boards on aluminum bases with thin polyimide dielectrics for use in electronic modules and printed circuit assemblies (including with using Chip-on-board and Chip-on-flex technologies for assembling) have been studied.

Search and analysis of results of theoretical and experimental studies on literature and patent sources in fields of optical and optical-electronic instrumentation are carried out. Current state and development trends of transparent polymer compositions containing nanoscale fillers, which open up new prospects for optical and optical-electronic instrumentation, are considered. Obtained data and recommendations on improvement and creation of new optically transparent nanocomposites are generalized, and can be used not only for connecting components of optical systems, but also for products in scintillation technology, lighting engineering, photovoltaics, and in many other fields of science and technology. Examples of some currently existing polymer and nanopolymer optical systems are considered, including an organosilicon composition for connecting optical elements, a plastic scintillator with nanostructured phosphors with improved time characteristics and light output values, an LED with multilayered scatterer with a variable index of refraction and an improved yield of radiation, optical compositions with a high refractive index on high transparency silicones for connection with optical elements in light-emitting devices or for lighting devices with a remote phosphor, as well as new materials and methods for dispersing nanoparticles. Given examples clearly show that complexity of the structures and micro dimensions of modern optical and optoelectronic products for their successful implementation and widespread adoption require new easy-to-use and not expensive optically transparent nanomaterials and technologies for their manufacture.

Objective.Proton therapy is highly sensitive to range uncertainties due to the nature of the dose deposition of charged particles. To ensure treatment quality, range verification methods can be used to verify that the individual spots in a pencil beam scanning treatment fraction match the treatment plan. This study introduces a novel metric for proton therapy quality control based on uncertainties in range verification of individual spots.Approach.We employ uncertainty-aware deep neural networks to predict the Bragg peak depth in an anthropomorphic phantom based on secondary charged particle detection in a silicon pixel telescope designed for proton computed tomography. The subsequently predicted Bragg peak positions, along with their uncertainties, are compared to the treatment plan, rejecting spots which are predicted to be outside the 95% confidence interval. The such-produced spot rejection rate presents a metric for the quality of the treatment fraction.Main results.The introduced spot rejection rate metric is shown to be well-defined for range predictors with well-calibrated uncertainties. Using this method, treatment errors in the form of lateral shifts can be detected down to 1 mm after around 1400 treated spots with spot intensities of 1 × 107protons. The range verification model used in this metric predicts the Bragg peak depth to a mean absolute error of 1.107 ± 0.015 mm.Significance.Uncertainty-aware machine learning has potential applications in proton therapy quality control. This work presents the foundation for future developments in this area.

A prototype of a new type of calorimeter has been designed and constructed, based on a silicon-tungsten sampling design using pixel sensors with digital readout. It makes use of the ALPIDE sensor developed for the ALICE Inner Tracking System (ITS) upgrade. A binary readout is possible due to the pixel size of approximate to 30 x30 mu m2. This prototype has been successfully tested with cosmic muons and with test beams at DESY and the CERN SPS. We report on performance results obtained at DESY, showing good energy resolution and linearity, and compare to detailed MC simulations. Also shown are preliminary results of the high-energy performance as measured at the SPS. The two-shower separation capabilities are discussed.

Silicon Tracker for RAdioactive nuclei Studies at SAMURAI Experiments is a new detection system under construction for quasi-free scattering (QFS) measurements at 200–250 MeV/nucleon at the RIBF facility of the RIKEN Nishina Center. It consists of a charged-particle silicon tracker coupled with a dedicated thick liquid hydrogen target (up to 150-mm long) in a compact geometry to fit inside large scintillator or germanium arrays. Its design was optimized for two types of studies using QFS: missing-mass measurements and in-flight prompt γ -ray spectroscopy. This article describes (i) the resolution requirements needed to go beyond the sensitivity of existing systems for these two types of measurements, (ii) the conceptual design of the system using detailed simulations of the setup and (iii) its complete technical implementation and challenges. The final tracker aims at a sub-mm reaction vertex resolution and is expected to reach a missing-mass resolution below 2 MeV in σ for (p, 2p) reactions when combined with the CsI(Na) CATANA array.

The first evaluation of an ultra-high granularity digital electromagnetic calorimeter prototype using 1.0–5.8 GeV/c electrons is presented. The 25 × 10 6 pixel detector consists of 24 layers of ALPIDE CMOS MAPS sensors, with a pitch of around 30 μm, and has a depth of almost 20 radiation lengths of tungsten absorber. Ultra-thin cables allow for a very compact design. The properties that are critical for physics studies are measured: electromagnetic shower response, energy resolution and linearity. The stochastic energy resolution is comparable with the state-of-the art resolution for a Si-W calorimeter, with data described well by a simulation model using Geant4 and Allpix 2 . The performance achieved makes this technology a good candidate for use in the ALICE FoCal upgrade, and in general demonstrates the strong potential for future applications in high-energy physics.

A forward electromagnetic and hadronic calorimeter (FoCal) was proposed as an upgrade to the ALICE experiment, to be installed during LS3 for data-taking in 2027–2029 at the LHC. The FoCal extends the scope of ALICE, which was designed for the comprehensive study of hot and dense partonic matter, by adding new capabilities to explore the small-x parton structure of nucleons and nuclei. The primary objective of the FoCal is high-precision inclusive measurement of direct photons and jets, as well as coincident gamma-jet and jet-jet measurements, in pp and p–Pb collisions. These measurements by FoCal constitute an essential part of a comprehensive small-x program at the LHC down to x∼10^-6 and over a large range of Q^2 with a broad array of complementary probes, comprising – in addition to the photon measurements by FoCal and LHCb – Drell-Yan and open charm measurements planned by LHCb, as well as photon-induced reactions performed by all LHC experiments.

Max Aehlea Johan Almeb Gergely Gábor Barnaföldic Johannes Blühdorna Tea Bodovab Vyacheslav Borshchovd Anthony van den Brinke Mamdouh Chaarb Viljar Eikelandb Gregory Feofilovf Christoph Garthg Nicolas R. Gaugera Georgi Genovb Ola Grøttvikb Håvard Helstruph Sergey Igolkinf Ralf Keideli Chinorat Kobdajj Tobias Kortusi Viktor Leonhardtg Shruti Mehendaleb Raju Ningappa Mulawadei Odd Harald Odlandk, b George O’Neillb Gábor Pappl Thomas Peitzmanne Helge Egil Seime Pettersenk Pierluigi Piersimonib,m Rohit Pochampallia Maksym Protsenkod Max Rauchb Attiq Ur Rehmanb Matthias Richtern Dieter Röhrichb Max Sagebauma Joshua Santanai Alexander Schillingi Joao Secoo, p Arnon Songmoolnakb, j Jarle Rambo Sølieq Ganesh Tambaveb Ihor Tymchukd Kjetil Ullalandb Monika Varga-Kofaragoc Lennart Volzr, s Boris Wagnerb Steffen Wendzeli Alexander Wiebeli RenZheng Xiaob, t Shiming Yangb Hiroki Yokoyamae Sebastian Zillieni

Issues of direct modeling effective thermal conductivity of two-component thermally conductive polyimide composite films based on polyimide thermosetting varnishes and thermally conductive powder fillers are considered. 3D-structural modeling of elementary cubic cells of polyimide composites has been performed. Calculations of average heat fluxes and effective thermal conductivity of variants of polyimide composite films with the introduction of highly thermally conductive highly dispersed and ultradispersed powder fillers into the polyimide matrix were carried out, including those from SiO2, SiC, Al2O3, AlN, taking into account boundary and initial conditions using COMSOL MULTIPHYSICS software. Specific recommendations are proposed for direct modeling of the thermal conductivity of environments with a complex structure and for carrying out with sufficient reliability numerical calculations of the effective thermal conductivity of polyimide composite films in order to increase their thermal conductivity from 0,12 W/(m•K) up to 1-4 W/(m•K) by changing concentration and thermal conductivity of mixtures of filler particles of micron and ultramicron sizes.

Search and analysis of results of theoretical and experimental studies, materials of dissertations, literature sources and patents in the field of optical and optoelectronic instrumentation were carried out. Obtained data and recommendations on the development of methods for dispersing nanoparticles into polymer matrices for the creation of optically transparent nan composites for use in many fields of science and technology are generalized. Analysis of considered results makes it possible to conclude that for creating hybrid organic-inorganic composites with high level of dispersion of inorganic component, it is necessary to solve problems relating to compatibility of components and stabilization of filler nanoparticles in polymer matrix. Due to the limited range of hydrophilic polymers capable of forming composites with nanoparticles without stabilizers, the main approaches to the preparation of hybrid composites are using modifying additives of surfactants, as well as complex chemical reactions on the surface of inorganic filler nanoparticles. Such methods of obtaining nanocomposites with nanoparticles are laborious and involve formation of by-products and additional purification. It is shown that titanium dioxide (TiO2) and zinc oxide (ZnO) are of great interest among a large number of nanodispersed fillers of polymer matrices in preparing composite materials. There are many methods for synthesis of ZnO and TiO2 nanoparticles with various shapes and sizes, including laser ablation method, which is convenient and universal method for preparing nanosuspensions of solid-phase materials in liquid. Advantages over other methods for nanoparticle synthesis, such as the simplicity of method, environmental friendliness, low cost, and the ability to obtain cleaner colloidal solutions without using surfactants and other impurities, have made laser ablation in a liquid medium very popular among researchers.

Background Proton computed tomography (pCT) and radiography (pRad) are proposed modalities for improved treatment plan accuracy and in situ treatment validation in proton therapy. The pCT system of the Bergen pCT collaboration is able to handle very high particle intensities by means of track reconstruction. However, incorrectly reconstructed and secondary tracks degrade the image quality. We have investigated whether a convolutional neural network (CNN)-based filter is able to improve the image quality. Material and methods The CNN was trained by simulation and reconstruction of tens of millions of proton and helium tracks. The CNN filter was then compared to simple energy loss threshold methods using the Area Under the Receiver Operating Characteristics curve (AUROC), and by comparing the image quality and Water Equivalent Path Length (WEPL) error of proton and helium radiographs filtered with the same methods. Results The CNN method led to a considerable improvement of the AUROC, from 74.3% to 97.5% with protons and from 94.2% to 99.5% with helium. The CNN filtering reduced the WEPL error in the helium radiograph from 1.03 mm to 0.93 mm while no improvement was seen in the CNN filtered pRads. Conclusion The CNN improved the filtering of proton and helium tracks. Only in the helium radiograph did this lead to improved image quality.

Radiation therapy using protons and heavier ions is a fast-growing therapeutic option for cancer patients. A clinical system for particle imaging in particle therapy would enable online patient position verification, estimation of the dose deposition through range monitoring and a reduction of uncertainties in the calculation of the relative stopping power of the patient. Several prototype imaging modalities offer radiography and computed tomography using protons and heavy ions. A Digital Tracking Calorimeter (DTC), currently under development, has been proposed as one such detector. In the DTC 43 longitudinal layers of laterally stacked ALPIDE CMOS monolithic active pixel sensor chips are able to reconstruct a large number of simultaneously recorded proton tracks. In this study, we explored the capability of the DTC for helium imaging which offers favorable spatial resolution over proton imaging. Helium ions exhibit a larger cross section for inelastic nuclear interactions, increasing the number of produced secondaries in the imaged object and in the detector itself. To that end, a filtering process able to remove a large fraction of the secondaries was identified, and the track reconstruction process was adapted for helium ions. By filtering on the energy loss along the tracks, on the incoming angle and on the particle ranges, 97.5% of the secondaries were removed. After passing through 16 cm water, 50.0% of the primary helium ions survived; after the proposed filtering 42.4% of the primaries remained; finally after subsequent image reconstruction 31% of the primaries remained. Helium track reconstruction leads to more track matching errors compared to protons due to the increased available focus strength of the helium beam. In a head phantom radiograph, the Water Equivalent Path Length error envelope was 1.0 mm for helium and 1.1 mm for protons. This accuracy is expected to be sufficient for helium imaging for pre-treatment verification purposes.