Transition Radiation Detector Research Articles

Advances in nuclear detection and readout techniques

“A Craftsman Must Sharpen His Tools to Do His Job,” said Confucius. Nuclear detection and readout techniques are the foundation of particle physics, nuclear physics, and particle astrophysics to reveal the nature of the universe. Also, they are being increasingly used in other disciplines like nuclear power generation, life sciences, environmental sciences, medical sciences, etc. The article reviews the short history, recent development, and trend of nuclear detection and readout techniques, covering Semiconductor Detector, Gaseous Detector, Scintillation Detector, Cherenkov Detector, Transition Radiation Detector, and Readout Techniques. By explaining the principle and using examples, we hope to help the interested reader underst and this research field and bring exciting information to the community.

J/ψ production at midrapidity in p-Pb collisions at sqrt{s_{textrm{NN}}} = 8.16 TeV

The production of inclusive, prompt and non-prompt J/ψ was studied for the first time at midrapidity (−1.37 < ycms< 0.43) in p-Pb collisions at sqrt{s_{textrm{NN}}} = 8.16 TeV with the ALICE detector at the LHC. The inclusive J/ψ mesons were reconstructed in the dielectron decay channel in the transverse momentum (pT) interval 0 < pT< 14 GeV/c and the prompt and non-prompt contributions were separated on a statistical basis for pT> 2 GeV/c. The study of the J/ψ mesons in the dielectron channel used for the first time in ALICE online single-electron triggers from the Transition Radiation Detector, providing a data sample corresponding to an integrated luminosity of 689 ± 13 μb−1. The proton-proton reference cross section for inclusive J/ψ was obtained based on interpolations of measured data at different centre-of-mass energies and a universal function describing the pT-differential J/ψ production cross sections. The pT-differential nuclear modification factors RpPb of inclusive, prompt, and non-prompt J/ψ are consistent with unity and described by theoretical models implementing only nuclear shadowing.

Transition radiation detectors for hadron separation in the forward direction of LHC experiments

Studies in many areas of particle and astroparticle physics require a good knowledge of hadron spectra produced at small angles to the primary particle direction, e.g. in the TeV energy range at the LHC. The present work is dedicated to development of a particle identification technique based on the transition radiation produced by highly relativistic particles. Dedicated experimental studies were carried out and simulation models were developed to reproduce experimental data obtained with different prototypes. On the basis of these studies, the possibility of making detectors able to provide hadron composition measurement with high accuracy and identify particles with high efficiency in the forward experiments at the LHC was demonstrated. Two concepts of large scale TRDs are proposed: the straw TRD and the GaAs/straw TRD. They allow the reconstruction of hadron spectra with accuracy about or below 1% and to identify particles with high efficiency in individual events. As an example, suppression of the combinatorial background was demonstrated for the D0→K−π+ and D̄0→K+π− decays.

Development of ML FPGA Filter for Particle Identification and Tracking in Real Time

Real-time data processing is a frontier field in experimental particle physics. Machine Learning methods are widely used and have proven to be very powerful in particle physics. The growing computational power of modern FPGA boards allows us to add more sophisticated algorithms for real time data processing. Many tasks could be solved using modern Machine Learning (ML) algorithms which are naturally suited for FPGA architectures. The FPGA-based machine learning algorithm provides an extremely low, sub-microsecond, latency decision and makes information-rich data sets for event selection. Work has started to evaluate an FPGA based Machine Learning (ML) algorithm for a real-time particle identification and tracking with Transition Radiation Detector (TRD) and e/m calorimeter. The first target is the GlueX experiment, with a plan to build a TRD based on GEM technology. GlueX trigger latency is 3.3 μs.

Monte Carlo simulation of HERD side-on transition radiation detector prototype

The High Energy cosmic-Radiation Detection facility (HERD) is a calorimetry-based cosmic-ray detection mission on board China space station. A side-on transition radiation detector (TRD) focuses on the TeV energy range calibration of the HERD calorimeter with an error of less than 10% by measuring the Lorentz factor γ of high-energy cosmic-ray protons. A side-on TRD prototype was developed for the performance study and tested by Deutsches Elektronen-Synchrotron electron beams. In this paper, the Monte Carlo simulation based on GEANT4 was compared with the experiment results. All simulations were in good agreement with the test beam results.

An event display for the Transition Radiation Detector in ALICE

Particle collider experiments generate huge volumes of complex data, and event displays provide a useful visual representation to accelerate the learning process towards physics results. Event displays are also used to verify expected behaviour, identify anomalous data, or explain important results. They often have a steep learning curve, a high barrier to entry, or are tightly bound to a specific environment. The upgrade of ALICE in preparation for Run 3 of the LHC requires modifications to existing event displays. We present here a cross-platform, browser-based event display, focused on interactive 2-dimensional projections of collision data from ALICE, specifically focused on the operation of the Transition Radiation Detector (TRD). It is driven by a flexible intermediate JSON data format suitable for web-based displays, and a generic task to convert existing data acquired in previous runs to this format. The relationship between raw and reconstructed data in the TRD is illustrated through a novel pairing of raw and reconstructed data in a unified interactive view. A formal design study methodology was used to guide these choices, and the display was evaluated by both scientists and the public, through a series of case studies.

Construction and test of a transition-radiation detector prototype based on thick gas electron multiplier technology

A transition-radiation detector (TRD) is a powerful device for highly relativistic electron (γ ≳ 1,000) identification. Electron identification is crucial for tagging the outgoing scattered electrons in an electron-ion collider (EIC) detector. Employing a TRD at the electron forward region of an EIC detector can provide the necessary electron identification with high hadron rejection over a wide momentum range. Thick gas electron multiplier (THGEM) technology is suitable for radiation detection in modern high-energy experiments owing to its high-granularity structure, radiation hardness, high-rate capability and ease of large-area production. This study investigates a TRD prototype based on THGEM technology through soft X-ray and electron beam experiments. Geant4 simulation were extensively exploited to understand the operation of TRD prototype with different gas mixtures. Particularly, the performance of TRD prototype with an electron beam at the DESY, with argon-based gas rather than xenon-based gas, agreed well with the simulation analyses in all important aspects. Based on the consistency of the experimental and simulation results, a likelihood analysis on the simulated total energy deposit in the xenon-based working gas would suggest a pion rejection improvement with the optimization of detector design, readout electronics and identification algorithm.

Attaining the PeV frontier of the cosmic ray spectrum in space with HERD

The High Energy cosmic-Radiation Detection facility (HERD) is a calorimetric experiment planned to be launched in 2027. It will be operational for at least 10 years on board the China Space Station. With HERD we will measure the energy flux of cosmic protons and heavier nuclei from 30 GeV up to, for the first time in space, a few PeV. We will search for signatures of annihilation and decay products of dark matter in the energy spectrum of cosmic electrons and gamma rays from 10 GeV to 100 TeV. A wide field of view monitoring of the gamma-ray full-sky from 100 MeV will also be performed. The five HERD subdetectors, the calorimeter (CALO), the scintillating fiber tracker (FIT), the plastic scintillator detector (PSD), the silicon charge detector (SCD) and the transition radiation detector (TRD), are currently under development. The design, prospects and expected performance of HERD, as well as its contribution to the multimessenger astronomy will be presented in this contribution.

Latest advancements of the HERD space mission

The High Energy cosmic-Radiation Detection (HERD) facility is one of the leading projects among future space-borne instruments to be installed on-board the Chinese Space Station (CSS), around 2027. Its main scientific goals include: accurate measurements of Cosmic Ray (CR) energy spectra up to the highest achievable energies in space (∼ few PeV), gamma-ray astronomy and transient studies, along with indirect searches for Dark Matter (DM). HERD is uniquely configured to accept particles from both its top and four lateral sides. Due to its novel design, an order of magnitude increase in geometric acceptance is foreseen, compared to current generation experiments. HERD is configured around a highly-segmented (55 X0, 3 λI) 3D calorimeter (CALO). A Fiber Tracker (FIT) is installed on all active sides, with a Plastic Scintillator Detector (PSD) covering both instruments. Finally, a Silicon Charge Detector (SCD) envelops the aforementioned sub-detectors, while a Transition Radiation Detector (TRD) is situated on one of the lateral sides, for energy calibration in the TeV range. A detailed overview of HERD will be provided in this contribution, with emphasis on recent detector advancements, ongoing and upcoming activities.

Overview of the HERD space mission

The High Energy cosmic Radiation Detector (HERD) is a prominent space-borne instrument to be installed on-board the Chinese Space Station (CSS) around 2027, resulting from a collaboration among Chinese and European institutions. Primary scientific goals of HERD include: precise measurements of the cosmic ray (CR) energy spectra and mass composition at energies up to few PeV, electron/positron spectra up to tens of TeV, CR anisotropy, gamma ray astronomy and transient studies, along with indirect searches for Dark Matter candidates. The detector is configured to accept incident particles from both its top and four lateral sides. Owing to its pioneering design, more than one order of magnitude increase in geometric acceptance is foreseen, with respect to previous and ongoing experiments. HERD is conceived around a deep (∼55 X 0, 3 λ I ) 3D cubic calorimeter (CALO), forming an octagonal prism. Fiber Trackers (FiTs) are instrumented on all active sides, with a Plastic Scintillator Detector (PSD) covering the calorimeter and tracker. Ultimately, a Silicon Charge Detector (SCD) envelops the above-stated sub-detectors, while a Transition Radiation Detector (TRD) is instrumented on one of its lateral faces, for energy calibration in the TeV scale. This work illustrates HERD’s latest advancements and scientific objectives along with an overview of upcoming activities.

Extending the Lorentz factor range and sensitivity of transition radiation with compound radiators

Transition radiation detectors (TRDs) have been used to identify high-energy particles (in particular, to separate electrons from heavier particles) in accelerator experiments. In space, they have been used to identify cosmic-ray electrons and measure the energies of cosmic-ray nuclei. To date, radiators have consisted of regular configurations of foils with fixed values of foil thickness and spacing (or foam or fiber radiators with comparable average dimensions) that have operated over a relatively restricted range of Lorentz factors. In order to extend the applicability of future TRDs (for example, to identify 0.5–3 TeV pions, kaons, and protons in the far forward region in a future accelerator experiment or to measure the energy spectrum of cosmic-ray nuclei up to 20 TeV/nucleon or higher), there is a need to increase the signal strength and extend the range of Lorentz factors that can be measured in a single detector. A possible approach is to utilize compound radiators consisting of varying radiator parameters. We discuss the case of a compound radiator and derive the yield produced in a TRD with an arbitrary configuration of foil thicknesses and spacings.

The photon yield efficiency study of transition radiators at E2 line of Beijing Test Beam Facility

A variety of transition radiators consisting of polypropylene, foam, and sponge materials have been studied for the transition radiation detector in the High Energy cosmic-Radiation Detection (HERD) facility. The test was implemented at the Beijing Test Beam Facility (BTBF) using an electron beam with an energy of 2.5 GeV. It is a simple and effective method that used two identical detectors to study the photon yield efficiency of radiators and it is here denoted as the current ratio method. Based on this method, a parameter χ was defined to evaluate the absolute TR photon yield per electron of the radiator. The polypropylene radiator GXU0.5 × 300 demonstrated an excellent absolute yield of 4.05 ± 0.97 photons per electron. The experimental results were compared with the corresponding TR generation models in Geant4 and the difference between them in regular radiators was in the range of 1%-7%. The research results of absolute photon yield may provide some reference for future research on radiators.

A concept of the transition radiation detector for a hadron separation in a forward direction of the LHC experiments

Studying of hadron production in forward direction at the LHC energy has a great interest both for understanding of the fundamental QCD processes and also in applied areas such as the description of ultra-high energy cosmic particle interactions. The energies of secondary hadrons in such studies almost reach the maximum energy available at the LHC of ~6 TeV, which corresponds to a Lorentz γ-factor up to 104 and above. The only effective technique able to identify particles in this range is based on the transition radiation detectors (TRD). Prototypes of such kind of detector were built and tested at the CERN SPS accelerator. Some experimental results obtained in these tests are briefly presented here and compared with Monte Carlo (MC) simulations. MC model demonstrates a good agreement with the experiment. On this basis a concept of a full-scale TRD optimized for the hadron identification in the TeV energy region is proposed. Different particle identification techniques were considered and examined. The expected detector performance to reconstruct secondary hadrons produced in forward direction at the LHC is presented.

Study of charge sharing effect in a GaAs:Cr-based Timepix3 detector

Hybrid pixel semiconductor detectors find more and more applications in modern experimental physical setups. In particular, pixelated detectors based on GaAs:Cr sensor and Timepix3 chip are used in R&D for a state-of-the-art Transition Radiation Detector prototype at CERN. Motivation and usage aspects for GaAs:Cr-Timepix3 device in the experiment are covered in the talk. Authors” contribution to the work of the research group is a study of charge collection and transportation processes in the sensor including fluorescence and so-called charge sharing effect. These are able to significantly affect both spatial and energy resolution of the system. Estimates for the effects are obtained via numerical modelling and then used to analyze the impact on the detector performance.

Side-On transition radiation detector (TRD) based on THGEM

The characteristic that TR energy is proportional to the Lorentz factor provides a way for energy calibration. The High Energy cosmic-Radiation Detection calorimeter can be calibrated in space by the TRD in the future. In order to make the TR signal stand out from the energy loss signal, a new prototype of TRD called Side-On TRD with THGEM has been built. Side-on TRD uses side window incidence and strip readout to reduce the ionization energy registered in the channel where the TR photons are located, which is supposed to improve the detection efficiency of TR. The Side-On TRD has been tested at CERN SPS and found the experimental results are significant.

Side-On transition radiation detector: A detector prototype for TeV energy scale calibration of calorimeters in space

Transition Radiation (TR) plays an important role in particle identification in high-energy physics and its characteristics provide a feasible method of energy calibration in the energy range up to 10 TeV, which is of interest for dark matter searches in cosmic rays. In a Transition Radiation Detector (TRD), the TR signal is superimposed onto the ionization energy loss signal induced by incident charged particles. In order to make the TR signal stand out from the background of ionization energy loss in a significant way, we optimized both the radiators and the detector. We have designed a new prototype of regular radiator optimized for a maximal TR photon yield, combined with the Side-On TRD which is supposed to improve the detection efficiency of TR. We started a test beam experiment with the Side-On TRD at Conseil Européen pour la Recherche Nucléaire (CERN), and found that the experimental data is consistent with the simulation results.

Studies of the spectral and angular distributions of transition radiation using a silicon pixel sensor on a Timepix3 chip

X-ray transition radiation detectors (TRDs) are used for particle identification in both high energy physics and astroparticle physics. In most of the detectors, emission of the X-ray transition radiation (TR) starts at Lorentz factors above γ∼500 and reaches saturation at γ∼2÷3⋅103. However, many experiments require particle identification up to γ∼105, which is very difficult to achieve with conventional detectors. Semiconductor pixel detectors offer a unique opportunity for precise simultaneous measurements of spectral and angular parameters of TR photons. Test beam studies of the energy and the angular distributions of TR photons emitted by electrons and muons of different momenta crossing several types of radiators were performed at the CERN SPS with a 480 μm thick silicon detector bonded to a Timepix3 chip. High resolution images of the energy−angle phase space of the TR produced by different radiators were obtained and compared with MC simulations. The characteristic interference patterns are in agreement with the theoretical models with an unprecedented level of details. The studies presented in this paper also show that simultaneous measurements of both the energy and the emission angles of the TR X-rays could be used to enhance the particle identification performances of TRDs.

Effects of the thermal blanket on AMS-02

This study evaluates effects of the thermal blanket on various components of AMS-02 using telemetry data from before and after installation. In principle, the thermal blanket stabilizes the temperature of the covered components. When the external heat flux increases, the thermal blanket restrains the increase in the component temperature. In contrast, when the external heat flux decreases, the thermal blanket reduces the heat dissipation. The thermal blanket effectively solves low-temperature warnings of BOX-C, a vital component of the gas circulation system in the Transition Radiation Detector (TRD) located on the port-wake side of AMS-02. However, the effect on inner components, which are not covered by the thermal blanket, is less significant. In the meantime, the thermal blanket prevents heat dissipation from the interior of AMS-02 to the outer space, which can cause high-temperature warnings at internal components such as the Power Distribution System (PDS) and the photomultiplier tubes in the Time of Flight (TOF).

DARMA - INFORMATION SYSTEM FOR ACCESSING LHC DATA WITHIN THE ALICE EXPERIMENT AT CERN

The paper deals with the implementation of systems for remote data access in cooperation with the international laboratory CERN in Geneva. The first part discusses extensions of the DARMA information system for archive management. The main goal of this paper is to design and enhance the system with new functionalities and solve known shortcomings, and thus qualitatively increase the potential of the DARMA system in the context of the ALICE DCS (Detector Control System). The final part of the paper deals with the analysis of historical data and the design of a system for the anomaly and failure detection in the infrastructure of high voltage channels within the TRD detector (Transition Radiation Detector).

Space-point calibration of the ALICE TPC with track residuals

In the LHC Run 3, starting in 2021, the upgraded Time Projection Chamber (TPC) of the ALICE experiment will record minimum bias Pb–Pb collisions in a continuous readout mode at an interaction rate up to 50 kHz. This corresponds to typically 4-5 overlapping collisions during the electron drift time in the detector. Despite careful tuning of the new quadruple GEM-based readout chambers, which fulfill the design requirement of an ion backflow below 1%, these conditions will lead to space-charge distortions of several centimeters that fluctuate in time. They will be corrected via a calibration procedure that uses the information of the Inner Tracking System (ITS), which is located inside, and the Transition Radiation Detector (TRD) and Time-Of-Flight system (TOF), located around the TPC, respectively. By using such a procedure the intrinsic track resolution of the TPC of a few hundred micrometers can be restored. The required online tracking algorithm for the TRD, which is based on a Kalman filter, is presented. The procedure matches extrapolated ITS-TPC tracks to TRD space-points utilizing GPUs. Subsequently these global tracks are refitted neglecting the TPC information. The residuals of the TPC clusters to the interpolation of the refitted tracks are used to create a map of spacecharge distortions. Regular updates of the map compensate for changes in the TPC conditions. The map is applied in the final reconstruction of the data. First performance results of the tracking algorithm will be shown.