Future High Energy Physics Experiments Research Articles

Ionizing Radiation Effects in Silicon Photonics Modulators

Silicon photonics (SiPh) shows considerable potential as a radiation-hard technology for building the optical data transmission links for future high-energy physics (HEP) experiments at CERN. Optical modulators are a key component of optical links, which will need to withstand radiation doses in excess of 10 MGy. The geometrical parameters and doping concentrations of two popular types of SiPh modulators, Mach–Zehnder and ring modulators (RMs), have been varied in order to study their impact on the device radiation tolerance. They were exposed to an X-ray beam to test their resistance to ionizing radiation. The RM with the highest doping concentration is shown to be the most tolerant, showing no degradation in performance up to the highest dose of 11 MGy. Moreover, we report first evidence of the dependence of the radiation tolerance on the RM operating temperature.

Spectral Response of UV Photodetectors for Barium Fluoride Crystal Readout

Because of its fast scintillation peaked at 220 nm with a decay time of less than 0.6 ns, barium fluoride crystals have attracted broad interest in the community pursuing ultrafast detectors for future high energy physics (HEP) experiments and GHz hard X-ray imaging for future X-ray free-electron laser (XFEL) facilities. A crucial issue for its application is the spectral response of photodetectors down to vacuum ultraviolet (VUV). In this article, we compare quantum efficiency (QE) and photon detection efficiency (PDE) spectra measured for several ultraviolet (UV) photodetectors down to 200 nm. Their figures of merit on the detection efficiency for the fast component and the suppression of the slow component are also discussed.

Gamma-Ray Interaction of Selected Inorganic Scintillators Used in HEP Experiments

We attempted to study gamma-ray attenuation and sensing properties of conventional and modern inorganic scintillators being employed in the high energy physics (HEP) experiments. The mass attenuation coefficient (μm ), effective atomic number (Zeff ) and mean free path (mfp)were theoretically evaluated for the conventional scintillators materials such as CsI and NaI (Tl) and compared with advanced scintillator materials: PWO, PbF2, and BGO along with rare earth elements based scintillators such as LYSO:Ce, LuAG:Ce, BaF2:Y which have been proposed for applications in the future HEP experiments. Thegamma-ray attenuation parameters are analyzed within the framework of online software toolkit ‘py-MULBF’ over wide photon energy range from 0.015 MeV to 15 MeV.Variationof μm (and, Zeff ) with photon energy follows a trend similar for most of the inorganic scintillator materialsinvestigated here.CsI, however, maintained almost same effective atomic number value with respect to photon energy which signifies that CsI may be suitable for specific gamma-ray detection and sensing applications. Lead-based scintillator materials such as PbF2, PWO along with high-Z BGO are observed to exhibit better radiation attenuation capabilities.

Time Resolution of an Irradiated 3D Silicon Pixel Detector

We report on the measurements of time resolution for double-sided 3D pixel sensors with a single cell of 50 μm × 50 μm and thickness of 285 μm, fabricated at IMB-CNM and irradiated with reactor neutrons from 8 ×1014 1MeV neq/cm2 to 1.0 ×1016 1MeV neq/cm2. The time resolution measurements were conducted using a radioactive source at a temperature of −20 and 20 °C in a bias voltage range of 50–250 V. The reference time was provided by a low gain avalanche detector produced by Hamamatsu. The results are compared to measurements conducted prior to irradiation where a temporal resolution of about 50 ps was measured. These are the first ever timing measurements on an irradiated 3D sensor and which serve as a basis for understanding their performance and to explore the possibility of performing 4D tracking in high radiation environments, such as the innermost tracking layers of future high energy physics experiments.

Hadron-Induced Radiation Damage in LuAG:Ce Scintillating Ceramics

Because of their potential low cost, bright light, and fast decay time, LuAG:Ce ceramic scintillators have attracted a broad interest in the high-energy physics community. One crucial issue for their application in future high-energy physics experiments is their radiation hardness against neutrons and protons expected at future hadron colliders. We report optical and scintillation performance of 1-mm LuAG:Ce ceramic samples doped with Mg^2&#x002B; (and Ca^2&#x002B;) and their radiation damage induced by hadrons. While Mg^2&#x002B; co-doping improves their light output, Ca^2&#x002B; co-doping improves their fast to total (F/T) ratio. LuAG:Ce ceramic samples were irradiated at the Los Alamos Neutron Science Center (LANSCE), Los Alamos, NM, USA, by neutrons up to <inline-formula> <tex-math notation="LaTeX">$6.7\times 10^{15}\,\,\text{n}_{\mathrm {eq}}$ </tex-math></inline-formula>/cm² and by 24-GeV and 800-MeV protons at CERN PS-IRRAD up to <inline-formula> <tex-math notation="LaTeX">$1.2\times 10^{15}$ </tex-math></inline-formula> p/cm² and at LANSCE up to <inline-formula> <tex-math notation="LaTeX">$2.3\times 10^{14}$ </tex-math></inline-formula> p/cm², respectively. All samples show excellent radiation hardness with more than 90&#x0025; of light after irradiation. The RIAC values induced by neutrons are found to be a factor of 2 smaller than lutetium&#x2013;yttrium oxyorthosilicate (LYSO:Ce) crystals. The RIAC values induced by protons are also found a factor of 2 smaller than LYSO:Ce crystals in LuAG:Ce ceramic samples with good optical quality. Research and development will continue to develop LuAG:Ce scintillating ceramics with improved optical quality for future investigation.

Sensitivity of lepton flavor violation process B+ → K+μ−τ+ in future experiments

The upcoming upgrades of Large Hadron Collider (LHC) to High Luminosity LHC (HL-LHC) and the proposed Future Circular Collider (FCC-hh) offer an opportunity of observing the Lepton Flavor Violating (LFV) process beyond the Standard Model. Monte Carlo simulation of generating and detecting an LFV process [Formula: see text] on CMS at LHC (Run-3), HL-LHC, and FCC-hh reference detector (FRD) is performed. This process is favored by the leptoquark models, particularly the three-site Pati–Salam model but disfavored by the gauged [Formula: see text] model, both of which are introduced to address the [Formula: see text] anomalies. We study possible backgrounds with similar final states and use Multi-Variable Analysis (MVA) to discriminate signal events from possible backgrounds. The MVA output is used to estimate Single Event Sensitivity (SES) of this process, yielding encouraging results on CMS at HL-LHC and FRD at FCC-hh with considerable SES values of about [Formula: see text] (CMS, LHC Run-3), [Formula: see text] (CMS, HL-LHC) and [Formula: see text] (FRD, FCC-hh), suggesting it’s promising to probe such process in the future high energy physics experiments and constrain the new physics models more rigorously.

Negative capacitance devices: sensitivity analyses of the developed TCAD ferroelectric model for HZO

This work aims to investigate the suitability of innovative negative capacitance (NC) devices to be used in High Energy Physics experiments detection systems, featuring self-amplified, segmented, high granularity detectors. Within this framework, MFM (Metal-Ferroelectric-Metal) and MFIM (Metal-Ferroelectric-Insulator-Metal) structures have been investigated within the Technology-CAD environment. The strength of this approach is to exploit the behavior of a simple capacitor to accurately ad-hoc customize the TCAD library aiming at realistically modeling the polarization properties of devices fabricated with ferroelectric materials. The comparison between simulations and measurements in terms of polarization as a function of the applied electric field for both MFM and MFIM devices has been used for modeling and methodologies validation purposes. The analyses and results obtained for MFIM capacitors can be straightforwardly extended to the study of NC-FETs. This work would support the use of the TCAD modeling approach as a predictive tool to optimize the design and the operation of the new generation NC-FET devices for the future High Energy Physics experiments in the HL-LHC scenario. The NC working principle will be employed for particle detection applications in order to exceed the limits imposed by current CMOS technology in terms of power consumption, signal detectability and switching speed.

TCAD simulations of non-irradiated and irradiated low-gain avalanche diodes and comparison with measurements

In this work, the results of Technology-CAD (TCAD) device-level simulations of non-irradiated and irradiated Low-Gain Avalanche Diode (LGAD) detectors and their validation against experimental data will be presented. Thanks to the intrinsic multiplication of the charge within these silicon sensors, it is possible to improve the signal to noise ratio thus limiting its drastic reduction with fluence, as it happens instead for standard silicon detectors. Therefore, special attention has been devoted to the choice of the avalanche model, which allows the simulation findings to better fit with experimental data. Moreover, a radiation damage model (called “New University of Perugia TCAD model”) has been fully implemented within the simulation environment, to have a predictive insight into the electrical behavior and the charge collection properties of the LGAD detectors, up to the highest particle fluences expected in the future High Energy Physics (HEP) experiments. This numerical model allows to consider the comprehensive bulk and surface damage effects induced by radiation on silicon sensors. By coupling the “New University of Perugia TCAD model” with an analytical model that describes the mechanism of acceptor removal in the multiplication layer, it has been possible to reproduce experimental data with high accuracy, demonstrating the reliability of the simulation framework.

The Impact of Microelectronics on High Energy Physics Innovation: The Role of 65 nm CMOS Technology on New Generation Particle Detectors

The High Luminosity Large Hadron Collider (HL-LHC) at CERN will constitute a new frontier for the particle physics after the year 2027. Experiments will undertake a major upgrade in order to stand this challenge: the use of innovative sensors and electronics will have a main role in this. This paper describes the recent developments in 65 nm CMOS technology for readout ASIC chips in future High Energy Physics (HEP) experiments. These allow unprecedented performance in terms of speed, noise, power consumption and granularity of the tracking detectors.

Characterizing ultralow emittance electron beams using structured light fields

Novel schemes for generating ultra-low emittance electron beams have been developed in the last years and promise compact particle sources with excellent beam quality suitable for future high-energy physics experiments and free-electron lasers. Current methods for the characterization of low emittance electron beams such as pepperpot measurements or beam focus scanning are limited in their capability to resolve emittances in the sub $0.1$ mm mrad regime. Here we propose a novel, highly sensitive method for the single shot characterization of the beam waist and emittance using interfering laser beams. In this scheme, two laser pulses are focused under an angle creating a grating-like interference pattern. When the electron beam interacts with the structured laser field, the phase space of the electron beam becomes modulated by the laser ponderomotive force and results in a modulated beam profile after further electron beam phase advance, which allows for the characterization of ultra-low emittance beams. 2D PIC simulations show the effectiveness of the technique for normalized emittances in the range of $\epsilon_n=[0.01,1]$ mm mrad.

Quantum field theory with the generalized uncertainty principle II: Quantum Electrodynamics

Continuing our earlier work on the application of the Relativistic Generalized Uncertainty Principle (RGUP) to quantum field theories, in this paper we study Quantum Electrodynamics (QED) with minimum length. We obtain expressions for the Lagrangian, Feynman rules and scattering amplitudes of the theory, and discuss their consequences for current and future high energy physics experiments. We hope this will provide an improved window for testing Quantum Gravity effects in the laboratory.

A multichannel front-end readout ASIC for picosecond time resolution systems based on thin UFSD

This work presents FAST, a multichannel readout ASIC designed to measure the time of arrival of MIP particles in Ultra-Fast Silicon Detectors (UFSD) with a time resolution of about 30 ps. The FAST ASIC is oriented to future High Energy Physics experiments, where high time resolution is exploited to mitigate pile-up effects, and more generally, to those applications that require accurate Time-of-Flight Silicon systems with low power consumption. The prototype has been designed in 110 nm CMOS technology, in three different flavors of front-end architecture. Each flavor is implemented in a different 20-channel ASIC. For all flavors, the power consumption of the front-end is 1.2 mW/channel. The three flavors of FAST are described in the paper, together with the simulation showing the timing performance of FAST coupled to different sensors geometries.

Characterisation of an RPC prototype with moderate resistivity plates using tetrafluoroethane (C2H2F4)

Keeping in mind the requirements of high rate capable, cost effective, large area detectors to be used in future high energy physics experiments, commercially available bakelite plates having moderate bulk resistivity are used to build an RPC module. The chamber is tested with cosmic rays in the avalanche mode using 100% Tetrafluoroethane (C2H2F4). Standard NIM electronics are used for this study. The efficiency, noise rate and time resolution are measured. The detailed method of measurement and the first test results are presented.

Neutron-Induced Radiation Damage in LYSO, BaF2, and PWO Crystals

One crucial issue for the application of scintillation crystals in future high-energy physics experiments is radiation damage in a severe radiation environment, such as the high luminosity large hadron collider. While radiation damage induced by ionization dose in inorganic scintillators is well understood, investigations are ongoing to understand radiation damage induced by hadrons, including both charged hadrons and neutrons. Aiming at understanding neutron-induced radiation damage in fast inorganic scintillators, lutetium yttrium oxyorthosilicate (LYSO)/lutetium fine silicate (LFS), BaF2, and PWO crystals were irradiated at Los Alamos Neutron Science Center by a combination of particles, including neutrons, protons, and $\gamma $ -rays. The results indicate that LYSO/LFS and BaF2 crystal plates are radiation hard up to a 1-MeV equivalent neutrons fluence of $9 \times 10^{15}$ equivalent neutron (neq)/cm2, but not PWO, and the neutron-induced radiation damage in LYSO crystals is a factor of ten less than protons.

Investigation of heterogeneous computing platforms for real-time data analysis in the CBM experiment

Future experiments in high-energy physics will pose stringent requirements to computing, in particular to real-time data processing. As an example, the CBM experiment at FAIR Germany intends to perform online data selection exclusively in software, without using any hardware trigger, at extreme interaction rates of up to 10 MHz. In this article, we describe how heterogeneous computing platforms, Graphical Processing Units (GPUs) and CPUs, can be used to solve the associated computing problems on the example of the first-level event selection process sensitive to J/ψ decays using muon detectors. We investigate and compare pure parallel computing paradigms (Posix Thread, OpenMP, MPI) and heterogeneous parallel computing paradigms (CUDA, OpenCL) on both CPU and GPU architectures and demonstrate that the problem under consideration can be accommodated with a moderate deployment of hardware resources, provided their compute power is made optimal use of. In addition, we compare OpenCL and pure parallel computing paradigms on CPUs and show that OpenCL can be considered as a single parallel paradigm for all hardware resources.

Improvement of the timing properties of Ce-doped oxyorthosilicate LYSO scintillating crystals

The aim of this work has been to improve the time resolution of radiation detectors for future high-energy physics experiments and medical imaging applications. Ce-doped oxyorthosilicate Lu2SiO5:Ce (LSO) and mixed oxyorthosilicate Lu1.6Y0.4SiO5:Ce (LYSO) have been investigated as prospective scintillators for such high-time-resolution applications. A differential optical absorption technique with sub-picosecond time resolution upon selective excitation of Ce3+ ions to different excited states has been adopted to study carrier dynamics in these scintillators, and coincidence time resolution measured using 511 keV γ-quanta has been exploited to test their timing properties. A delay in population of the emitting level of Ce3+ has been observed, and is interpreted in terms of electron trapping, which is more pronounced in mixed yttrium-containing LYSO crystals due to composition fluctuations. It is shown that the delay, which affects the luminescence response time, can be eliminated by co-doping of LYSO:Ce with calcium at concentrations as low as 5 ppm. The faster kinetics of electron transfer correlates with a better coincidence time resolution. Thermalization and spatial distribution of non-equilibrium carriers has been studied theoretically to link the results obtained by the time-resolved differential optical absorption technique with the behavior of the non-equilibrium carriers generated by irradiation.

Effective Dynamic Integration and Utilization of Heterogenous Compute Resources

Increased operational effectiveness and the dynamic integration of only temporarily available compute resources (opportunistic resources) becomes more and more important in the next decade, due to the scarcity of resources for future high energy physics experiments as well as the desired integration of cloud and high performance computing resources. This results in a more heterogenous compute environment, which gives rise to huge challenges for the computing operation teams of the experiments. At the Karlsruhe Institute of Technology (KIT) we design solutions to tackle these challenges. In order to ensure an efficient utilization of opportunistic resources and unified access to the entire infrastructure, we developed the Transparent Adaptive Resource Dynamic Integration System (TARDIS). A scalable multi-agent resource manager providing interfaces to provision as well as dynamically and transparently integrate resources of various providers into one common overlay batch system. Operational effectiveness is guaranteed by relying on COBalD – the Opportunistic Balancing Daemon and its simple approach of taking into account the utilization and allocation of the different resource types, in order to run the individual workflows on the best-suited resource respectively. In this contribution we will present the current status of integrating various HPC centers and cloud providers into the compute infrastructure at the Karlsruhe Institute of Technology as well as our experiences gained in a production environment.

Characterization of irradiated p-type silicon detectors for TCAD surface radiation damage model validation

In this work we address the effects of surface radiation damage on detectors fabricated on high-resistivity p-type FZ ⟨ 100⟩ substrates by Hamamatsu Photonics (HPK) and by Infineon Technologies (IFX). Test structures underwent a wide set of measurements before and after X-ray irradiation with doses from 0.05 to 100 Mrad (SiO2) in order to extract the integrated interface trap density (NIT) and the oxide charge (QOX) peculiar to different vendors, processes and technology options. These parameters can be then used as inputs to TCAD simulation tools. On the basis of the new experimental evidences at these high doses, the TCAD numerical model has been updated considering two main bands of defects, one acceptor and one donor, extended to the whole silicon bandgap and simulating the net effect of the radiation-induced acceptor-like and donor-like defects. The comparison between simulation findings and measured macroscopic electric behaviour, e.g. in terms of C–V curves of MOS capacitors has been used as cross-check for model validation purposes. By means of the same modelling scheme it is possible to reproduce the I–V curves of gated-diodes and the interstrip resistance as a function of the dose from 0.05 to 100 Mrad (SiO2) for the range of technology and design options investigated. The good agreement between simulations and measurements would support the use of this TCAD surface radiation damage model as a predictive tool to optimize the design and the operations of the new generation of silicon detectors for the future High Energy Physics experiments.

The DIRAC interware: current, upcoming and planned capabilities and technologies

Efficient access to distributed computing and storage resources is mandatory for the success of current and future High Energy and Nuclear Physics Experiments. DIRAC is an interware to build and operate distributed computing systems. It provides a development framework and a rich set of services for the Workload, Data and Production Management tasks of large scientific communities. A single DIRAC installation provides a complete solution for the distributed computing of one, or more than one collaboration. The DIRAC Workload Management System (WMS) provides a transparent, uniform interface for managing computing resources. The DIRAC Data Management System (DMS) offers all the necessary tools to ensure data handling operations: it supports transparent access to storage resources based on multiple technologies, and is easily expandable. Distributed Data management can be performed, also using third party services, and operations are resilient with respect to failures. DIRAC is highly customizable and can be easily extended. For these reasons, a vast and heterogeneous set of scientific collaborations have adopted DIRAC as the base for their computing models. Users from different experiments can interact with the system in different ways, depending on their specific tasks, expertise level and previous experience using command line tools, python APIs or Web Portals. The requirements of the diverse DIRAC user communities and hosting infrastructures triggered multiple developments to improve the system usability: examples include the adoption of industry standard authorization and authentication infrastructure solutions, the management of diverse computing resources (cloud, HPC, GPGPU, etc.), the handling of high-intensity work and data flows, but also advanced monitoring and accounting using no-SQL based solutions and message queues. This contribution will highlight DIRAC’s current, upcoming and planned capabilities and technologies.

Performance of n-on-p planar pixel sensors with active edges at high-luminosity environment

Future high-energy physics experiments require highly segmented silicon sensors of increased geometrical efficiency with the ability to withstand extremely high radiation damage. The performance of planar n-on-p sensors with active edges is simulated at high radiation fluences up to 1 × 1016 neq/cm2, using a three-level trap model for p-type silicon material. Taking advantage of the secondary ion mass spectrometry (SIMS) technique, an accurate representation of the structure was obtained in terms of doping profile. The breakdown voltage, leakage current, hole density and electric field distributions as well as the charge collection efficiency (CCE) are studied as a function of radiation fluence.