High Energy cosmic-Radiation Detection Research Articles

Analysis and correction of crosstalk in the side-on transition radiation detector prototype for HERD

The side-on Transition Radiation Detector (TRD) is an essential component of the High Energy cosmic-Radiation Detection (HERD) facility aboard the China Space Station (CSS). Utilizing the proportional correlation between the Lorentz factor γ and Transition Radiation (TR) intensity, the side-on TRD collaborates with the HERD calorimeter for cross-calibration in the TeV energy range while orbiting. This paper focuses on analyzing and correcting signal crosstalk in the side-on TRD prototype. A signal caused by crosstalk, referred to as the “reversed polarity signal”, affects the particle signal and biases the prototype's energy measurement. To address the issue of energy deviation and select the most suitable capacitance for the prototype to correct crosstalk, we analyze the source of the reversed polarity signal and the effectiveness of adding a decoupling capacitor to the voltage divider circuit. Additionally, we use a combination of simulation and experimentation to investigate the specific relationship between the reversed polarity signal and the decoupling capacitance. The comparison between the simulation results and the experimental results show consistent trends. Measured energy spectra shows that correcting crosstalk eliminates a maximum measurement deviation of approximately 10.79% in the prototype. Following this correction, the side-on TRD prototype completed beam experiments in 2022.

Design and implementation of a ground detection system for HERD-TRD front-end electronics

The Transition Radiation Detector (TRD) is a critical component of the High Energy Cosmic Radiation Detection (HERD) experiment, calibrating the electromagnetic calorimeter at the TeV energy range and observing X-rays in the all-sky survey. To support HERD-TRD test, a comprehensive ground detection system featuring a data acquisition (DAQ) board and host computer software was designed and implemented. The DAQ system manages data from six front-end electronics (FEE), totaling 768 detector channels, using an LVDS interface for high-speed scientific data transfer and an RS422 interface for command and telemetry. Gigabit Ethernet and mini USB enable real-time communication with the host computer. Host computer software developed on the QT platform efficiently manages data acquisition, storage, and display. The DAQ board offers a compact circuit design and complete functionality, and the host software provides an intuitive user interface. The DAQ board and host computer software have been tested to meet the design requirements. Performance tests show that the system realizes a stable data transfer rate of 360 Mbps over Gigabit Ethernet and 55 Mbps from the FEE to the DAQ board. The system has minimal noise and runs continuously for a week without data loss. In addition, a joint test with TRD using the 55Fe radioactive source was performed, and the particle signal was correctly acquired.

Radiation characterization of SiPMs for HERD PSD

Silicon photomultipliers (SiPMs) have been used in several space-borne missions, and the radiation effect as well as the performance degradation must be a concern during space operations. SiPMs will be used as photon-electric devices of the Plastic Scintillator Detector (PSD) for the High Energy Cosmic Radiation Detection (HERD) facility, and the performance change of these SiPMs under in-orbit radiation needs to be studied to satisfy the 10 years of in-orbit operation mission. In this study, the radiation damage and annealing for potential SiPM candidates including Hamamatsu and Novel Device Laboratory series have been done. The dark current for S14160-3010PS(HM10), S14160-3015PS(HM15), and EQR1511-3030D-S(NDL15) was observed to increase by a factor of 300, 400, and 200 after exposure to an equivalent on-orbit dose of 10 years. PSD showed a significant decrease in MIP detection capability after irradiation. In addition, annealing of neutron radiation damages in SiPM at temperatures 50 °C and room temperature is studied.

Application of a deep learning method for shower axis reconstruction in a 3D imaging calorimeter

We present a deep learning method based on Convolutional Neural Networks (CNN) to reconstruct the shower axis of isotropic electrons in a three-dimensional (3D) imaging calorimeter, which is one of the core instruments of the High Energy cosmic-Radiation Detection (HERD) payload. The CNN method is evaluated against the Principal Component Analysis (PCA) method, utilizing isotropic Monte Carlo (MC) simulation data covering an energy spectrum from 10 GeV to 1000 GeV, as well as beam test data ranging from 50 GeV to 250 GeV. The comparative analysis results indicate that the CNN outperforms the PCA by about 40% at 100 GeV in terms of angular resolution under isotropic conditions. Both methods are further validated using beam test data. The results demonstrate the effectiveness of the CNN method in reconstructing the shower axis, and they underscore the potential of incorporating advanced deep learning techniques into the comprehensive task of calorimeter reconstruction.

A novel charge reconstruction algorithm applied to the HERD prototype silicon charge detector

The High Energy Cosmic-Radiation Detection (HERD) facility is a space astronomy and particle astrophysics experiment planned to be installed on the China Space Station. HERD can detect high-energy cosmic rays ranging from GeV to PeV and high-energy gamma rays. The silicon charge detector (SCD) is one of the subdetectors of HERD, measuring the charge and trajectory of incident ions. An ion beam test of the SCD prototype was conducted at CERN in 2022. A novel charge reconstruction algorithm based on the capacitive coupling was developed to study the charge resolution of the SCD prototype, and compared with the classical reconstruction algorithm.

Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

Design and prototyping of the readout electronics for the transition radiation detector in the high energy cosmic radiation detection facility

The Silicon Charge Detector of the High Energy Cosmic Radiation Detection experiment

The High Energy Cosmic Radiation Detector (HERD) is an experiment designed for direct measurement of cosmic rays on the Chinese Space Station in 2027. Its goals include precise measurements of cosmic ray energy spectra, mass composition, electron/positron spectra, cosmic rays anisotropy, gamma ray astronomy and indirect searches for Dark Matter. HERD features a 55X0, homogeneous, 3D segmented imaging calorimeter and can detect particles from the top and four lateral sides, providing precise energy measurements and electron/proton separation for a wide field of view. A key detector in HERD is the Silicon Charge Detector (SCD). SCD measures the charge of particles before interaction with other materials, minimizing cosmic rays nuclei fragmentation and reducing systematics on nuclei flux measurement. Thorough studies, TCAD and/or SPICE simulations, and accelerator tests on prototypes have been conducted to evaluate the tracking and charge resolution capabilities of the SCD. Further testing with 300 μm detectors is planned in the coming months to fully characterize the SCD's performance. This paper presents the results of the simulation studies and of the measured performance with particles.

Optimization of WLS fiber readout for the HERD calorimeter

A novel 3-D calorimeter, composed of about 7500 LYSO cubes, is the key and crucial detector of the High Energy cosmic-Radiation Detection (HERD) facility to be installed onboard the China Space Station. Energy deposition from cosmic ray in each LYSO cube is translated by multiple wavelength shifting (WLS) fibers for multi-range data acquisition and real-time triggering.In this study, various methods of surface finish and encapsulation of the LYSO cube were investigated to optimize the amplitude from the WLS fiber end with the aim of improving the signal-to-noise ratio of Intensified scientific CMOS (IsCMOS) collection. The LYSO cube with five rough surfaces and a specular reflector achieves the maximum amplitude at the low-range fiber end, which is increased by roughly 44% compared to the polished cube with PTFE wrapping.The non-uniformity of amplitude at different positions on the LYSO cube surface was measured by X-ray and the positional correlation factor was derived for the entire cube. A simulation based on HERD CALO was conducted, which revealed that both the LYSO cube with five rough surfaces and the cube with rough bottom face exhibit superior energy resolution for electrons compared to the other two configurations.

Potential for Constraining Propagation Parameters of Galactic Cosmic Rays with the High Energy Cosmic-radiation Detection Facility on Board China’s Space Station

Precise measurements of the spectra of secondary and primary cosmic rays are crucial for understanding the origin and propagation of those energetic particles. The High Energy Cosmic-radiation Detection (HERD) facility on board China’s Space Station, which is expected to operate in 2027, will push the direct and precise measurements of cosmic-ray fluxes up to PeV energies. In this work, we investigate the potential of HERD for studying the propagation of cosmic rays using measurements of boron, carbon, and oxygen spectra. We find that, compared with the current results, the new HERD measurements can improve the accuracy of the propagation parameters by 8%–40%. The constraints on the injection spectra at high energies will also be improved.

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.

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.

Preliminary tests of Plastic Scintillator Detector for the High Energy cosmic-Radiation Detection (HERD) experiment

The High Energy Cosmic Radiation Detection (HERD) facility, onboard the future China’s Space Station (CSS), will provide high quality data on charged cosmic rays and gamma rays in the energy range from few GeV to PeV. HERD will be equipped with a fine granularity cubic crystals calorimeter and a precision tracker detector. The entire instrument will be surrounded by a Plastic Scintillator Detector (PSD) that will be used to discriminate charged from neutral particles in order to correctly identify gamma-rays and nuclei. One proposed configuration for the HERD PSD consists of tiles of plastic scintillator, optically coupled to SiPMs. In 2019-2020, two beam tests were performed at CNAO (Centro Nazionale di Adroterapia Oncologica) in Pavia (Italy), exposing some PSD tiles, equipped with SiPMs, to low-beta p and C ion beams in order to evaluate the detector response to heavy ions. Spatial and temporal resolution were also evaluated using a radioactive source.

Assembly and test of prototype scintillator tiles for the plastic scintillator detector of the High Energy Cosmic Radiation Detection (HERD) facility

Satellite experiments for gamma-ray and cosmic-ray detection employ plastic scintillators to discriminate charged from neutral particles in order to correctly identify gamma-rays and charged nuclei. The High Energy Cosmic Radiation Detection (HERD) facility will be among these experiments, to be installed onboard the future Chinese Space Station (CSS), to detect cosmic-rays and gamma-rays up to TeV energies. The plastic scintillator detector (PSD) will consist of scintillator tiles or bars coupled to Silicon Photomultipliers (SiPMs). To discriminate gamma-rays from charged particles and measure the ion charge up to iron nuclei a wide dynamic range is required, from few tens up to thousands of photoelectrons. We have equipped a plastic scintillator tile prototype with SiPMs produced by Hamamatsu and AdvanSiD and coupled their analog signals to the DT5550W board based on the CITIROC ASIC, produced by CAEN SpA. The CITIROC ASIC allows both the formation of a fast trigger with a configurable threshold and the digitization of analog waveforms after a preamplification and shaping stage along two paths with different gain settings. The performance of our prototype will be shown.

Design and implementation of the double read-out system for the calorimeter of the HERD experiment

The High Energy cosmic-Radiation Detection (HERD) facility is a China-led international space mission that will start its operation around 2027 aboard the future China’s Space Station. The mission is expected to extend the direct measurements on cosmic rays and gamma rays by at least one order of magnitude in energy respect to the limits of the experiments currently operating in space. This is possible thanks to its novel design, based on a 3D, homogeneous, isotropic and finely-segmented calorimeter, with good energy resolution (< 1% for electromagnetic showers, < 30% for hadronic showers) and a good effective geometric factor (> 3 m2sr for electromagnetic showers, > 2 m2sr for hadronic showers). The main challenge of the hardware design is the implementation of the read-out system for each of the almost 8000 LYSO crystals of the calorimeter, since a large dynamic range of 107 is needed and absolute energy scale calibration is crucial for space instruments. In this contribution, we describe the double read-out scheme chosen for the final configuration, made of wave-length shifting fibers coupled with an intensified scientific CMOS and photodiodes connected to a specifically designed front-end electronics. In particular, we will discuss the advantages of both read-out systems and the benefits offered to the apparatus by this double read-out scheme.

Development of the photo-diode subsystem for the HERD calorimeter double-readout

The measurement of cosmic-ray individual spectra provides unique information regarding the origin and propagation of astro-particles. Due to the limited acceptance of current space experiments, protons and nuclei around the “knee” region (∼ 1 PeV) can only be observed by ground based experiments. Thanks to an innovative design, the High Energy cosmic-Radiation Detection (HERD) facility will allow direct observation up to this energy region: the instrument is mainly based on a 3D segmented, isotropic and homogeneous calorimeter which properly measures the energy of particles coming from each direction and it will be made of about 7500 LYSO cubic crystals. The read-out of the scintillation light is done with two independent systems: the first one based on wave-length shifting fibers coupled to Intensified scientific CMOS cameras, the second one is made of two photo-diodes with different active areas connected to a custom front-end electronics. This photo-diode system is designed to achieve a huge dynamic range, larger than 107, while having a small power consumption, few mW per channel. Thanks to a good signal-to-noise ratio, the capability of a proper calibration, by using signals of both non-interacting and showering particles, is also guaranteed. In this paper, the current design and the performance obtained by several tests of the photo-diode read-out system are discussed.

Prototype design and performance test of a cosmic ray tracker

The High Energy cosmic-Radiation Detection (HERD) facility has been proposed as one of the several space astronomy payloads onboard the future China’s Space Station (CSS), which is planned for operation starting around 2027 for about 10 years. A cosmic ray tracker with position resolution of better than 1 mm and effective detection area of 1 m × 1 m is designed to do detector performance study for sub-detector of the HERD on the ground. The tracker consisits of 1.0 m long scintillating fibers with a diameter of 1 mm which will be arranged in 3 staggered layers. The fibers will be read out by arrays of SiPMs. The performance of a small prototype module is built and tested with radioactive source 90-Sr and cosmic ray. The measured light output of the 3-layer fiber module is larger than 10 photoelectrons per MIP events.

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 preliminary simulation study of influence of backsplash on the plastic scintillator detector design in HERD experiment

The plastic scintillator detector (PSD) is one of the detectors in the high energy cosmic radiation detection (HERD) facility, which is designed for gamma-ray detection and a redundant charge measurement. Backsplash will lead to a decrease in PSD’s performance of gamma-ray detection and charge measurement, which should be carefully considered. Two preliminary segmentation schemes of the PSD and two veto strategies have been proposed to suppress the backsplash effect. In this paper, we focus on the influence of the backsplash caused by gamma rays. The gamma-ray trigger efficiency and identification efficiency were studied in the case of different cell sizes and veto strategies, which can provide guidance on the PSD design. A Monte Carlo simulation based on Geant4 has been performed. To simplify the simulation, the PSD is segmented into 1 cm3 cubes which can be easily aggregated into cells with different sizes during analysis. Side_Veto can be used as a baseline design of veto strategy, whereas Smart_Veto can be selected as an upgraded design. Both the PSD bar cell with a width of less than 11 cm and the PSD tile cell with a width of less than 20 cm can achieve a sufficiently high gamma-ray trigger efficiency (> 80%), which realizes the primary goal of the PSD. Meanwhile, both the PSD bar cell with a width of less than 3 cm and the PSD tile cell with a width of less than 20 cm can ensure a sufficiently high gamma-ray identification efficiency (> 80%) for photons up to 800 GeV.

Particle identification capability of Plastic scintillator tiles equipped with SiPMs for the High Energy cosmic-Radiation Detection (HERD) facility

The High Energy Cosmic Radiation Detection (HERD) facility onboard the future Chinese Space Station (CSS) will be able to detect charged cosmic rays and gamma rays from few GeV to PeV energies, giving a valuable contribution in several scientific topics, such as dark matter searches in astrophysical objects, the study of cosmic ray chemical composition and high energy gamma-ray observations. The entire instrument is supposed to be surrounded by a plastic scintillator detector (PSD), which will be used to discriminate charged from neutral particles in order to correctly identify gamma-rays and nuclei. One configuration proposed and studied for the HERD PSD detector consists in a segmented plastic scintillator with a squared-tile geometry, coupled to Silicon Photomultipliers (SiPMs). SiPMs provide similar or even better performances to the standard photomultiplier tubes (PMTs) with lower power consumption and cost benefits. In 2018, beam test campaigns were performed at CERN PS and SPS to test two prototypes of plastic scintillator tiles, equipped with a set of SiPMs. One was tested with a beam of electrons and pions and another prototype with an ion beam. The results will be presented, showing the capabilities of these prototypes to detect charged particles with very high efficiency and to measure the charge of heavier nuclei.