Particle Detectors Research Articles

Dynamical maps for accelerating detectors

We study the open quantum dynamics using the language of dynamical maps of a two-level particle detector that starts accelerating through Minkowski vacuum weakly coupled to a massless scalar field. We consider a detector with non-zero size and study its time evolution for the case where it is initially in inertial motion and subsequently a constant acceleration is switched on for a finite time. We study the dynamical maps that describe the evolution of such a system and show that the dynamics is not completely positive (NCP). The inertial motion prior to the acceleration can entangle the detector and field leading to the NCP dynamics. We examine the nature of the open dynamics during the accelerated phase as a function of the duration of prior inertial motion and the magnitude of the acceleration.

The Scintillation Counters of the High-Energy Particle Detector of the China Seismo-Electromagnetic (CSES-02) Satellite

The High-Energy Particle Detector (HEPD-02) is one of the scientific payloads of the China Seismo-Electromagnetic Satellite (CSES-02). The HEPD-02’s main purpose is to characterize the particle environment in the Earth’s vicinity, identifying sudden changes in the fluxes and correlating them with solar and terrestrial phenomena. Additionally, HEPD-02 also has capabilities in detecting Gamma-Ray Bursts. At the core of HEPD-02, a tower of scintillation counters made of plastic and LYSO crystals is able to recognize electrons in the range between 3 and 100 MeV, protons and nuclei between 30 and 200 MeV/n. Plastic scintillators covering the calorimeter on five sides allow to reject particles entering from the top and not completely absorbed within its volume. In this work, the design of the HEPD-02 is reviewed in comparison to its predecessor, HEPD-01, highlighting the innovations of the new design. The design of each scintillation counter type has been fully validated through a campaign of prototype realization, testing, and characterization. The production of the scintillation counters, including the PMT selection process, is also discussed. Finally, the performance of the counters is compared with simulations, showing an agreement of within 20% with the expected performance, thereby meeting expectations.

Introducing modern particle detectors in the classroom: a slice-by-slice overview

Abstract This paper aims to provide a basis for teachers interested in bringing modern particle detectors into their classrooms. In particular, it gives an overview of the basic principles of modern particle detectors, linking them to concepts that are already a part of the curriculum. In addition, it explains the essential detector components present in all detector systems, and how the information they provide leads to particle identification. By highlighting relevant classroom resources, this paper serves as a valuable guide for teachers seeking to include modern particle physics in their teaching, and to set it within interesting and relevant contexts.

Registration of the auroral near-UV emission by the orbital detector TUS

The TUS detector is a highly sensitive orbital telescope. Due to the polar orbit of the spacecraft, the detector made observations of the UV luminosity of the atmosphere above the aurora oval. Events with intensity variations characteristic of pulsating auroras have been registered. The events are located along the equatorial boundary of the auroral oval and occur during long-term geomagnetic disturbances. Comparison with data from charged particle detectors shows the presence of an increased flux of precipitating high-energy electrons (with energies above 100 keV) simultaneously with UV pulsations.

Monitoring kiloelectron-volt emission variability in partially observed nuclear events through distance weighted censored control charts

The variation in the lifespan of particles is a crucial parameter in nuclear physics and is essential for identification purposes. Modern particle detectors excel at recognizing individual radioactive nuclei arrivals and their subsequent decay events. However, challenges arise when matching arrivals with departures, especially when departures are only partially observed. One inefficient approach involves conducting experiments with very low arrival rates to facilitate matching. The kiloelectron-volt E(keV) emission is obtained during this radio active process. This study focuses on the meticulous surveillance of the standard deviation in keV emission from partially observed events within the domain of nuclear physics.The utilization of censored control charts allows for the effective management of incomplete data, enabling researchers to make informed decisions despite potential limitations in observation. To accomplish this, the methodology employs the statistical approach known as Distance Weighted Mean based Standard Deviation (DWMS) integrated with the application of censored control charts. We propose a DWMS based exponentially weighted moving (DWMS-E) control chart for monitoring kiloelectron-volt E(keV) data. The proposed charts is developed for Weibull lifetimes with type-I censored data. The goal is to find changes in the mean of Weibull lifetimes with known and estimated parameter conditions. The performance of the proposed DWMS-E chart is evaluated by the average run length (ARL). Besides a simulation study, a real-life data set on E(keV) related to the alpha decays of 177 Lutetium isotope is also discussed.

Scintillator-SiPM detector for tracking and energy deposition measurements

An innovative particle detector that offers a compelling combination of cost-effectiveness and high accuracy is introduced. The detector features plastic scintillators paired with a sparse arrangement of SiPMs, strategically positioned within a unique opto-mechanical framework. This configuration delivers precise measurements of spatial impact position and energy deposition of impinging particles. The manuscript describes the detector’s physical model complemented by an analytical representation. These calculations underpin a numerical algorithm, facilitating the estimation of particle impingement position and energy deposition. The results of the numerical calculations are compared with the output of GEANT4 simulations and evaluated by rigorous laboratory testing. An array of these detectors, intended for deployment in a spaceborne experiment, underwent detailed design, manufacturing, and testing. Their performance and alignment with the physical model were validated through meticulously conducted ground-based laboratory experiments, conclusively affirming the detector’s properties.

A comparison of deep learning models for proton background rejection with the AMS electromagnetic calorimeter

Abstract The alpha magnetic spectrometer (AMS) is a high-precision particle detector onboard the International Space Station containing six different subdetectors. The transition radiation detector and electromagnetic calorimeter (ECAL) are used to separate electrons/positrons from the abundant cosmic-ray proton background. The positron flux measured in space by AMS falls with a power law which unexpectedly softens above 25 GeV and then hardens above 280 GeV. Several theoretical models try to explain these phenomena, and a more accurate measurement of positrons at higher energies is needed to help test them. The currently used methods to reject the proton background at high energies involve extrapolating shower features from the ECAL to use as inputs for boosted decision tree and likelihood classifiers. We present a new approach for particle identification with the AMS ECAL using deep learning (DL). By taking the energy deposition within all the ECAL cells as an input and treating them as pixels in an image-like format, we train an MLP, a CNN, and multiple ResNets and convolutional vision transformers (CvTs) as shower classifiers. Proton rejection performance is evaluated using Monte Carlo (MC) events and ISS data separately. For MC, using events with a reconstructed energy between 0.2–2 TeV, at 90% electron accuracy, the proton rejection power of our CvT model is more than five times that of the other DL models. Similarly, for ISS data with a reconstructed energy between 50–70 GeV, the proton rejection power of our CvT model is more than 2.5 times that of the other DL models.

Multispacecraft Observations of Protons and Helium Nuclei in Some Solar Energetic Particle Events toward the Maximum of Cycle 25

The intricate behavior of particle acceleration and transport mechanisms complicates the overall efforts in formulating a comprehensive understanding of solar energetic particle (SEP) events; these efforts include observations of low-energy particles (from tens of keV to hundreds of MeV) by space-borne instruments and measurements by the ground-based neutron monitors of the secondary particles generated in the Earth atmosphere by SEPs in the GeV range. Numerous space-borne missions provided good data on the nature/characteristics of these solar particles in past solar cycles, but more recently—concurrently with the rise toward the maximum of solar cycle 25—the High-Energy Particle Detector (HEPD-01) proved to be well suited for the study of solar physics and space weather. Its nominal 30–300 MeV energy range for protons can enlarge the detection capabilities of solar particles at low Earth orbit, closer to the injection limit of many SEP events. In this work, we characterize three SEP events within the first six months of 2022 through spectral and velocity dispersion analysis, assessing the response of HEPD-01 to >M1 events.

The Global Characteristics of Electrons Near the Inner Edge of the Inner Radiation Belt

AbstractEnergetic electrons around the inner edge of the inner radiation belt (L1.3) have not been studied to the extent of the rest of the inner belt and certainly not to that of the outer radiation belt. Yet, the behavior of electrons at the inner edge of the inner belt could improve our understanding of important dynamics deep within Earth's magnetosphere. Previous work has analyzed these electrons during either isolated events or via significantly limited statistical studies, and it remains unclear what the particular drivers of electron flux enhancements in this region may be. Here, we present a broad statistical study of electrons around the inner edge of the inner radiation belt, utilizing the 7‐year data set of the MagEIS particle detectors aboard both Van Allen Probes spacecraft. Moreover, we separate electron flux measurements into stably trapped and quasi‐trapped electrons and directly compare their behavior. We find both populations to be variable in L and energy, as well as showing a clear magnetic local time (MLT) asymmetry. Potential drivers are also explored, where we demonstrate an association between increased electron fluxes in this region and heightened solar wind speed, Sym‐H, dynamic pressure, southward IMF and most prominently with the AU and AL indices.

A No-Fuss Particle Detector: An Inexpensive and Robust Way to See the Invisible

A No-Fuss Particle Detector: An Inexpensive and Robust Way to See the Invisible

Laser-fibre interface for single-particle detector amplification and transportation

Abstract Single quantum particle detectors (e.g. photo-multiplier tubes and electron multipliers) produce ns-output pulses that time-correlate to particles that enter them. The detector output pulses usually require amplification at source, before being sent to counting electronics for analysis. A laser-based transport system is detailed here that converts the detector output into light pulses that are injected into single mode fibre. Pulse delivery is then by fibre, so that electrical interference from the laboratory environment and earth grounding loops are eliminated. A fast photodiode and differential amplifier converts the signal exiting the fibre into a voltage pulse for subsequent timing experiments.

Beam tests of SNSPDs with 120 GeV protons

We report the test results for a 120GeV proton beam incident on superconducting nanowire particle detectors of various wire sizes. NbN devices with the same sensitive area were fabricated with different wire widths and tested at a temperature of 2.82K. The relative detection efficiency was extracted from bias current scans for each device. The results show that the wire width is a critical factor in determining the detection efficiency and larger wire widths than 400nm leads to inefficiencies at low bias currents. These results are particularly relevant for novel applications at accelerator facilities, such as the Electron-Ion Collider, where cryogenic cooling is readily available.

Enhanced Cherenkov radiation in twisted hyperbolic Van der Waals crystals

AbstractCherenkov radiation in artificial structures experiencing strong radiation enhancements promises important applications in free‐electron quantum emitters, broadband light sources, miniaturized particle detectors, etc. However, the momentum matching condition between swift electrons and emitted photons generally restricts the radiation enhancement to a particular momentum. Efficient Cherenkov radiation over a wide range of momenta is highly demanded for many applications but still remains a challenging task. To this end, we explored the interaction between swift electrons and twisted hyperbolic Van der Waals crystals and observed enhanced Cherenkov radiation at the flatband resonance frequency. We show that, at the photonic magic angle of the twisted crystals, the electron momentum, once matching with that of the flatband photon, gives rise to a maximum energy loss (corresponding to the surface phonon generation), one‐order of magnitude higher than that in conventional hyperbolic materials. Such a significant enhancement is attributed to the excitation of flatband surface phonon polaritons over a broad momentum range. Our findings provide a feasible route for highly directional free‐electron radiation and radiation shaping.

Differentiable vertex fitting for jet flavor tagging

This work explores the use of differentiable programming to integrate domain knowledge, in the form of domain specific software, into neural networks to develop scientific machine learning systems. We propose a differentiable vertex fitting algorithm that estimates the crossing point of multiple curves. In the high energy physics setting, these curves are defined by particle equations of motion and the crossing point represents the origin of particle production. This differentiable vertex fitting algorithm can be seamlessly integrated into neural networks, and we show its utility and efficacy in the high energy physics application of the classification of jets, i.e., collimated streams of particles in particle detectors whose originating parent particle we aim to classify. We demonstrate how differentiable vertex fitting can be integrated into larger transformer-based models for jet flavor tagging and show improvements in heavy flavor jet classification when compared to baseline models. Published by the American Physical Society 2024

Search for photons above 1018 eV by simultaneously measuring the atmospheric depth and the muon content of air showers at the Pierre Auger Observatory

The Pierre Auger Observatory is the most sensitive instrument to detect photons with energies above 1017 eV. It measures extensive air showers generated by ultrahigh energy cosmic rays using a hybrid technique that exploits the combination of a fluorescence detector with a ground array of particle detectors. The signatures of a photon-induced air shower are a larger atmospheric depth of the shower maximum (Xmax) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced cascades. In this work, a new analysis technique in the energy interval between 1 and 30 EeV (1 EeV=1018 eV) has been developed by combining the fluorescence detector-based measurement of Xmax with the specific features of the surface detector signal through a parameter related to the air shower muon content, derived from the universality of the air shower development. No evidence of a statistically significant signal due to photon primaries was found using data collected in about 12 years of operation. Thus, upper bounds to the integral photon flux have been set using a detailed calculation of the detector exposure, in combination with a data-driven background estimation. The derived 95% confidence level upper limits are 0.0403, 0.01113, 0.0035, 0.0023, and 0.0021 km−2 sr−1 yr−1 above 1, 2, 3, 5, and 10 EeV, respectively, leading to the most stringent upper limits on the photon flux in the EeV range. Compared with past results, the upper limits were improved by about 40% for the lowest energy threshold and by a factor 3 above 3 EeV, where no candidates were found and the expected background is negligible. The presented limits can be used to probe the assumptions on chemical composition of ultrahigh energy cosmic rays and allow for the constraint of the mass and lifetime phase space of super-heavy dark matter particles. Published by the American Physical Society 2024

NIM–TTL and TTL–NIM converters for single particle pulse counting experiments

Abstract Low-cost interface circuits are detailed that convert negative-going NIM signals to TTL and TTL to NIM, using high-speed digital and analogue components to convert between formats. By converting NIM pulses derived from single particle detectors to TTL logic, the large suite of TTL compatible devices available to manipulate, control and measure TTL signals can be exploited. Conversion of TTL pulses to NIM allows them to be used to trigger timing events, e.g. in time of flight measurements and coincidence studies. Examples using these techniques are presented.

Fusion neutron source and array of particle detectors for nondestructive interrogation of special nuclear materials

Presented herein are the outcomes of an experimental test involving a pioneering portable-active interrogation system designed for the nondestructive detection of special nuclear materials (SNMs). The system relies on the threshold energy neutron analysis concept and incorporates a portable deuterium–deuterium (DD) neutron generator producing a particle intensity of 5 × 107 n/s, coupled with three arrays of tensioned metastable fluid detectors (TMFDs) to detect secondary neutrons from the fissile material. In the presence of the fissile material, prompt fission neutrons are emitted, with an average energy of approximately 2 MeV, and around 30% of these neutrons have energies above that of the DD neutron source (2.45 MeV). The detection of a statistically significant neutron population exceeding this threshold firmly indicates the presence of SNM. TMFDs exhibit high sensitivity in efficiently detecting neutrons above the threshold while adeptly discriminating against neutrons below the threshold as well as gamma rays. This unique feature allows the interrogation system to maintain a lightweight profile without necessitating substantial shielding materials. The validation experiments involved the placement of 70 or 140 g masses of U-235 within a 1 m3 inspection volume. Measurements were carried out over 30 min intervals, repeated numerous times, both with and without U-235, at a DD neutron source intensity of 8 × 105 n/sec. Experimental count rates with natural uranium (NU) are consistently above those without NU. The probability of detection (PD) and probability of false alarm (PFA) were assessed utilizing these count rates. The DD neutron source intensity and inspection time were normalized at 5 × 107 n/sec and 90 s, respectively. The results indicated a PD of approximately 74% and 98% for detecting 70 and 140 g of U-235, respectively, with a PFA of <5%. These promising outcomes align with the specified PD (>90%) and PFA (<5%) targets outlined in ANSI standards.

Data quality control system and long-term performance monitor of LHAASO-KM2A

The KM2A is the largest sub-array of the Large High Altitude Air Shower Observatory (LHAASO). It consists of 5216 electromagnetic particle detectors (EDs) and 1188 muon detectors (MDs). The data recorded by the EDs and MDs are used to reconstruct primary information of cosmic-ray and gamma-ray showers. To ensure the reliability of the LHAASO-KM2A data, a three-level quality control system has been established. It is used to monitor the status of detector units, stability of reconstructed parameters and the performance of the array based on observations of the Crab Nebula and Moon shadow. This paper will introduce the control system and its application on the LHAASO-KM2A data collected from August 2021 to July 2023. During this period, the pointing and angular resolution of the array were stable. From the observations of the Moon shadow and Crab Nebula, the results achieved using the two methods are consistent with each other. For example, according to the observation of the Crab Nebula with KM2A at energies from 25 TeV to 100 TeV, the time averaged pointing errors are estimated to be −0.003°±0.005° and 0.001°±0.006° in the R.A. and Dec directions, respectively.

Simulating heavy neutral leptons with general couplings at collider and fixed target experiments

Heavy neutral leptons (HNLs) are motivated by attempts to explain neutrino masses and dark matter. If their masses are in the MeV to several GeV range, HNLs are light enough to be copiously produced at collider and accelerator facilities, but also heavy enough to decay to visible particles on length scales that can be observed in particle detectors. Previous studies evaluating the sensitivities of experiments have often focused on simple but not particularly well-motivated models in which the HNL mixes with only one active neutrino flavor. In this work, we accurately simulate models for HNL masses between 100 MeV and 10 GeV and arbitrary couplings to e, μ, and τ leptons. We include over 150 HNL production channels and over 100 HNL decay modes, including all of the processes that can be dominant in some region of the general parameter space. The result is , a user-friendly, fast, and flexible library to compute the properties of HNL models. As examples, we implement to extend the package to evaluate the prospects for HNL discovery at forward LHC experiments. We present sensitivity reaches for FASER and FASER2 in five benchmark scenarios with coupling ratios |Ue|2∶|Uμ|2∶|Uτ|2=1∶0∶0, 0∶1∶0, 0∶0∶1, 0∶1∶1, and 1∶1∶1, where the latter two have not been studied previously. Comparing these to current constraints, we identify regions of parameter space with significant discovery prospects. Published by the American Physical Society 2024

Recuperation systems for fluorinated gases at the CERN LHC Experiments

Particle detectors at the LHC experiments are very often characterised by large detector volumes and by the need of using very specific gases, some of which are greenhouse gases (GHGs). Given their high Global Warming Potential (GWP) and the increasingly stringent European regulations regarding the use and trade of these gases, CERN is today strongly committed to reduce GHGs emissions from particle detector operation. Different approaches have been adopted for reducing the GHG emissions. To achieve this objective, the CERN Gas Team has developed gas recuperation plants: i.e. systems designed to extract GHGs from the exhaust of gas recirculation systems allowing further re-use and, therefore, reducing drastically GHGs emissions without changing detectors operation conditions. They are industrial-scale systems, each of which relies on different principles for gas separation and purification. Considering the unique gas mixtures used in particle detectors, these recuperation systems have been specifically developed as no industrial apparatus currently exists to address these requirements. Recent developments are concerning plants for recuperation of CF4, C2H2F4 (also called R134a), SF6 and C4F10, which are used respectively for Cathode Strip Chambers, (CSCs) Resistive Plate Chambers (RPCs) and Ring-Imaging Cherenkov (RICH) detectors. The separation of fluorinated gases is carried out mainly through membranes, absorbers, or distillation. Two state-of-the-art recuperation systems are briefly described in this paper.