- Email: [email protected]
The HEPD detector on board CSES satellite: In flight performance
Accepted Manuscript The HEPD detector on board CSES satellite: In flight performance G. Osteria, V. Scotti, for the CSES-Limadou Collaboration PII: DOI: Reference:
S0168-9002(18)31417-7 https://doi.org/10.1016/j.nima.2018.10.102 NIMA 61424
To appear in:
Nuclear Inst. and Methods in Physics Research, A
Received date : 30 June 2018 Revised date : 10 October 2018 Accepted date : 15 October 2018 Please cite this article as: G. Osteria, et al., The HEPD detector on board CSES satellite: In flight performance, Nuclear Inst. and Methods in Physics Research, A (2018), https://doi.org/10.1016/j.nima.2018.10.102 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
*Manuscript Click here to view linked References
The HEPD detector on board CSES satellite: in flight performance G. Osteriaa,∗, V. Scottia , for the CSES-Limadou Collaborationb a Istituto
Nazionale di Fisica Nucleare - Sezione di Napoli, Naples, Italy b http://cses.roma2.infn.it/node/53
Abstract CSES (China Seismo-Electromagnetic Satellite) is a scientific mission dedicated to monitoring electromagnetic field, plasma and particles perturbations of atmosphere and inner Van Allen belts caused by solar and terrestrial phenomena and to the study of the low energy component of the cosmic rays. The satellite hosts several instruments onboard: two magnetometers, an electrical field detector, a plasma analyser, a Langmuir probe and two particle detectors. It has been successfully launched from the Jiuquan Satellite Launch Center located in west of inner Mongolia on February 2 2018 and is now orbiting in nominal condition. The high energy particle detector (HEPD), designed and built by the Italian Limadou collaboration, aims at investigating precipitation of trapped particles induced by atmospheric EM emissions, as well as by the seismo-electromagnetic disturbances. HEPD provides good energy resolution and high angular resolution for electrons (3-100 MeV) and proton (30-200 MeV). The instrument consists of: 2 planes of double-side silicon microstrip sensors placed on the top of the instrument (direction of particle); 2 two layers of plastic scintillators (trigger) and a calorimeter (constituted by other 16 scintillators and a layer of LYSO sensors). A scintillator veto system completes the instrument. The commissioning of the HEPD and the other instruments on board is in progress and will last several months. In this contribution we will describe the HEPD detector and the (preliminary) performance in flight. Keywords: Detector techniques for Cosmology and Astroparticle Physics, Satellite experiment PACS: 29.40.Cs, 29.40.Gx 1. Introduction On February 2, 2018, the China Seismo-Electromagnetic Satellite (CSES) was launched successfully into a Sunsynchronous orbit with 97.4◦ inclination, a height of about 500 km and an ascending node of 14:00 local time. The scientific payloads include a search-coil magnetometer [1], an electric field detector [2], a high precision magnetometer [3], a GNSS Occultation receiver, a plasma analyzer, a Langmuir probe, an energetic particle detector [4] [5], and a three-frequency beacon. The main scientific goal of the mission is the real-time monitoring of electromagnetic changes of the Earth system, especially within the ionosphere. In particular, the satellite monitors the perturbations of the electromagnetic field, plasma and inner Van Allen belt particles in the ionosphere induced by natural sources with the aim to study their correlations with the occurrence of seismic events. ∗ Corresponding
author Email address: [email protected] (G. Osteria)
Preprint submitted to Elsevier
The high-energy particle detector of the CSES satellite, described in this article, has been designed for investigating seismo-induced particles perturbations. The particles trapped in the geomagnetic field lines of the Van Allen belts execute gyro-motion, bouncing and longitudinal drift according with their adiabatic invariants. They are sensitive to both solar terrestrial interactions and the internal electromagnetic emissions from the geomagnetic cavity. All these effects constitute a background in studying possible electromagnetic perturbations induced by lithospheric processes. Even though with extremely less efficacious effects, also the seismo-electromagnetic fluctuations occurring in space are capable to generate local perturbations of the inner Van Allen belt. Anomalous sharp increases of electron and proton counting rates (from a few MeV to several tens and hundreds of MeV) were detected mostly below the inner Van Allen radiation belt, near the South Atlantic anomaly (SAA), at altitudes of about 400 –1200 km, by several space experiments. The existence of a temporal correlation between these anomalous fluctuations, called particle bursts (PBs), and October 10, 2018
Figure 1: An overview of the High-Energy Particle Detector. Figure 2: HEPD installed on CSES
the occurrence of earthquakes of medium and strong magnitude have been suggested by several authors [6] and confirmed by data obtained on board of METEOR-3A and AUREOL-3 satellites [7] [8]. By measuring energy spectrum, direction and composition of particle fluxes, HEPD will study the stability of the inner Van Allen belts and particles precipitation trying to carefully discriminate anomalous events possibly induced by seismicity from the natural background, caused by geomagnetic, tropospheric and anthropogenic electromagnetic emissions. Another very important scientific objective of the HEPD is the study of the solar-terrestrial environment, as Coronal Mass Ejections (CMEs), Solar Energetic Particle (SEP) events and low-energy cosmic rays. The CSES mission will monitor the solar impulsive activity and the cosmic ray solar modulation by detecting proton and electron fluxes from a few MeV to hundreds MeV. These measurements will provide an extension down to very low energy of the range of the particle spectra obtained in the current 24th solar cycle by PAMELA and AMS experiments. Moreover, fluxes of light nuclei up to hundreds MeV/n will be provided.
• Veto system, consisting of 5 plastic scintillator counters, four lateral and one at the bottom of the instrument. All the scintillators (plastic and inorganic) are read out by photomultiplier tubes (PMT R9880-210 from Hamamatsu). The Electronics Subsystem [9] of the HEPD can be schematized into three blocks: Silicon detector, Scintillator detectors (trigger, energy and veto detectors), Global control and data managing. Each detector block includes power chain for bias distribution and a data acquisition processing chain. The main Power Supply provides the low voltages to the detector electronics and the high bias voltages for PMTs and silicon modules. The HEPD has mechanical dimensions of 530 × 382 × 404 mm3 , a mass of 45 kg and a power consumption of about 27 W in its default flight configuration. Rejection of particles hitting the lateral or bottom veto planes is performed online or offline by using different trigger commands. An electron/proton separation for fully contained events greater than 90% is achieved by the ∆EvsEtot method, where ∆E is obtained by the two layers of the silicon tracker, while Etot is measured by the calorimeter. Other main parameters of HEPD are:
2. The High Energy Particle Detector
Nuclei identification: up to oxygen; Energy resolution: < 10% ; Angular resolution: < 8◦ ; Field of view: 60◦ .
The High-Energy Particle Detector (HEPD) is designed to detect electrons in the energy range between 3 and 100 MeV, protons between 30 and 200 MeV and light nuclei. The detector is made up of several sub-detectors arranged as shown in Fig.1:
Following the standard procedures for space applications, four models of HEPD have been built and fully integrated in the clean rooms at the INFN laboratories of Roma Tor Vergata in Rome (Italy). The electrical model (EM), the structural and thermal model (STM), the qualification model (QM), and, fimally, the flight model (FM). The flight model was shipped to China, in December 2016. In January 2017, the functionality of the instrument was successfully tested standalone with its EGSE; then it was installed on the CSES satellite (Figure 2 ) in December 2017, HEPD has been transferred to the Jiuquan Satellite Launch Center, China, in the Gobi desert (Inner Mongolia) from where it has been launched, by a Long March 2D rocket, on the February 2nd, 2018.
• Tracker: two planes of double-side silicon micro-strip detectors are placed on the top of the detector in order to track the direction of the incident particle limiting the effect of Coulomb multiple scattering on the direction measurement; • Trigger: a layer of thin plastic scintillator, placed 10 mm below the tracker, divided into six segments (200 × 30 × 5 mm3 each) along the y direction; • Calorimeter: a tower of 16 layers of 1 cm thick plastic scintillator planes followed by a 3x3 matrix of an inorganic scintillator LYSO. 2
Figure 5: The comparison between proton beam data and MC simulation for dE/dx measurements (preliminary reults).
Figure 3: Energy loss by 30 MeV electrons within the upper segment of the HEPD calorimeter. The second and third peaks are produced by the pile-up of 2 or 3 simultaneous electrons.
Figure 6: HEPD calibration plot as function of energy (preliminary). Figure 4: Total energy loss in the HEPD calorimeter for 70 MeV protons. Sigma/peak = 0.08.
output and real data have the same format and the same software is used to reconstruct the event in both cases, allowing a fair comparison of reconstructed parameters and Monte Carlo truth. In Figure 5, a comparison between proton beam data and MC simulation for dE/dx measurements in a ladder of the HEPD silicon tracker is shown (preliminary results). The plot in Figure 6 summarizes the (preliminary) results of the calibration of the detector performed on ground by test beams and atmospheric muons.
3. HEPD calibration Calibrations of the QM and FM were performed by electron and proton beams. Electron tests took place at the Beam Test Facility (BTF) at the INFN Frascati National Laboratories. The parameters of the BTF were optimized to obtain beam bunches of low multiplicity electrons, for different energies: 30 MeV, 45 MeV, 60 MeV, 90 MeV and 120 MeV. Data collected were transmitted to the EGSE module that was controlled remotely from the control room, so emulating the satellite orbiting conditions. QM and FM were calibrated at different incident angles and positions. The total energy loss in the calorimeter for 30 MeV electrons is shown in Fig. 3. One, two or three electrons hitting the instrument in a single beam bunch are clearly visible. The proton test was performed on the FM at the Proton Therapy Center in Trento (Italy), where a cyclotron produces protons at energies ranging between 70 and 230 MeV. Energies below 70 MeV were obtained by using a degrader along the beam line. The detector was irradiated with protons at different energies between 37 and 228 MeV. Fig. 4 illustrates the total energy loss in the FM calorimeter for 70 MeV protons [10]. A full GEANT4 simulation of the apparatus was performed, accounting for detector response to all particles and reproducing readout electronics and trigger conditions. Monte Carlo
4. HEPD in-flight operation After the launch, the commissioning phase of the HEPD has been very intensive. On the 6th February 2018, the HEPD health check procedure was successfully run. The day after HEPD was tested in the framework of the satellite platform verification. The payload operated along 3 orbits. Since the 12th of February 2018 HEPD has been tested in different configurations in order to: • study the trigger rates along the orbit in different trigger configurations; • study to define the optimal trigger thresholds in flight; • perform an in-flight calibration to be compared with beam test results. 3
Figure 8: Raw trigger rate map. Figure 7: ADC counts (proportional to energy release) on a channel of the second plane of the energy sub-detector. The two arrows indicate the MIP and the proton peaks.
etc.). The wide energetic range allows studying several phenomena beyond the seismo-associated ones, such as those related to magnetospheric currents, dynamics of radiation belts and cosmic rays flux. During the foreseen five years of the mission, a large part of the 24th solar cycle will be monitored.
The commissioning activities are still in progress and will last until the end of July 2018. Since the beginning of May 2018 an encrypted data transfer from China (CEA-ICS) to Italy (ASI-SSDC) has been working. The data retrieval, processing and storage in Italy has been implemented in a two nodes infrastructure with a shared file system providing high availability and high resilience of the storage. A processing pipeline has been developed as several layers of software with an interface to a processing database and to the storage of the infrastructure. About 400 GB of raw data have been downloaded from HEPD up to now and partially processed by the pipeline. The HEPD status is monitored in quasi-real time by quicklook software to get immediate information (strips and PMTs ADC counts, rate and orbital zones, trigger rate, etc).
Acknowledgments This work was supported by the Italian Space Agency in the framework of the Accordo Attuativo n. 2016-16-H0 Progetto Limadou Fase E/Scienza (CUP F12F1600011005). References [1] Cao J B, Zeng L, Zan F, et al. The electromagnetic wave experiment for CSES mission: Search coil magnetometer. Sci China Tech Sci, 2018, 61:653-658, https://doi.org/10.1007/s11431-018-9241-7 [2] L. Alfonsi et al. The HEPD particle detector and the EFD electric field detector for the CSES satellite. Radiation Physics and Chemistry, 2017, 137: 187-192, https://doi.org/10.1016/j.radphyschem.2016.12.022 [3] Cheng B, Zhou B, et al. High precision magnetometer for geomagnetic exploration onboard of the China Seismo-Electromagnetic Satellite. Sci China Tech Sci, 2018, 61:659-668, https://doi.org/10.1007/s11431-0189247-6 [4] Ambrosi G, Bartocci S, Basara L, et al. The HEPD particle detector of the CSES satellite mission for investigating seismo-associated perturbations of the Van Allen belts. Sci China Tech Sci, 2018, 61: 643-652, https://doi.org/10.1007/s11431-018-9234-9 [5] Scotti V, Osteria G. The high energy particle detector onboard the CSES satellite, https://doi.org/10.1109/NSSMIC.2016.8069878 [6] Galper A M, Koldashov S V, Voronov S A. High energy particle flux variations as earthquake predictors. Adv Space Res, 1995, 15: 131-134, https://doi.org/10.1016/0273-1177(95)00085-S [7] Galperin Yu I, Gladyshev V A, Jordjio N V, et al. Precipitation of highenergy captured particles in the magnetosphere above epicenter of an incipient earthquake. Cosmic Res, 1992, 30: 89-106 [8] Pustovetov V P, Malyshev A V. Spatial-temporal correlation of the earthquakes and variations of high-energy particle flux in the inner radiation belt. Cosmic Res, 1993, 31: 84-87 [9] Scotti V, Osteria G. The electronics of the HEPD of the CSES experiment, Nuclear and Particle Physics Proceedings, 291-293: 118-121 https://doi.org/10.1016/j.nuclphysbps.2017.06.024 [10] Panico P, et al. Study on the High Energy Particle Detector calorimeter, PoS(ICRC2017)172 [11] Sauvaud J A, et al. High-energy electron detection onboard DEMETER: The IDP spectrometer, description and first results on the inner belt. Planetary and Space Science 2006, 54: 502-511, https://doi.org/10.1016/j.pss.2005.10.019 [12] Bakaldin A V, et al. Satellite experiment ARINA for studying seismic effects in the high-energy particle fluxes in the Earths magnetosphere. Cosmic Res, 2007, 45: 445-448, https://doi.org/10.1134/S0010952507050085
5. HEPD preliminary results A first data analysis has been carried out to compare flight data to ground acquired data: beam test and atmospheric muon data. A comparison with atmospheric muon data confirms (figure 7) that pedestals, as well as the MIP peak, are in the same position, confirming that the behaviour of the detector is not changed after the launch. A comparison with beam test data confirms that the region between 2000 and 4000 ADC counts is mainly associated to a proton contribution. Measured trigger rate has an important background contribution due to fragmentation products, off acceptance and rehentrant particles. Figure 8 shows the raw trigger rate map. 6. Conclusion The HEPD detector has been designed, built and fully tested for measuring electrons in the energy range between 3 and 100 MeV, protons between 30 and 200 MeV and light nuclei up to oxygen. The HEPD configuration represents a substantial improvement (for detector reliability, particle identification, energy range, pitches angle resolution, etc.) with respect to all particle detectors (with similar objectives and energy range) recently launched (such as IDP on Demeter [11], ARINA [12], 4
Research Highlights
Highlights: • • • •
Seismo-associated disturbances in the ionosphere-magnetosphere transition zone Simultaneous measurements of different parameters of the seismo-associated perturbations Satellite hosting on board a suite of advanced instruments to study such phenomena Charge particle detector to study precipitation of particle bursts in the ionosphere
S0168-9002(18)31417-7 https://doi.org/10.1016/j.nima.2018.10.102 NIMA 61424
To appear in:
Nuclear Inst. and Methods in Physics Research, A
Received date : 30 June 2018 Revised date : 10 October 2018 Accepted date : 15 October 2018 Please cite this article as: G. Osteria, et al., The HEPD detector on board CSES satellite: In flight performance, Nuclear Inst. and Methods in Physics Research, A (2018), https://doi.org/10.1016/j.nima.2018.10.102 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
*Manuscript Click here to view linked References
The HEPD detector on board CSES satellite: in flight performance G. Osteriaa,∗, V. Scottia , for the CSES-Limadou Collaborationb a Istituto
Nazionale di Fisica Nucleare - Sezione di Napoli, Naples, Italy b http://cses.roma2.infn.it/node/53
Abstract CSES (China Seismo-Electromagnetic Satellite) is a scientific mission dedicated to monitoring electromagnetic field, plasma and particles perturbations of atmosphere and inner Van Allen belts caused by solar and terrestrial phenomena and to the study of the low energy component of the cosmic rays. The satellite hosts several instruments onboard: two magnetometers, an electrical field detector, a plasma analyser, a Langmuir probe and two particle detectors. It has been successfully launched from the Jiuquan Satellite Launch Center located in west of inner Mongolia on February 2 2018 and is now orbiting in nominal condition. The high energy particle detector (HEPD), designed and built by the Italian Limadou collaboration, aims at investigating precipitation of trapped particles induced by atmospheric EM emissions, as well as by the seismo-electromagnetic disturbances. HEPD provides good energy resolution and high angular resolution for electrons (3-100 MeV) and proton (30-200 MeV). The instrument consists of: 2 planes of double-side silicon microstrip sensors placed on the top of the instrument (direction of particle); 2 two layers of plastic scintillators (trigger) and a calorimeter (constituted by other 16 scintillators and a layer of LYSO sensors). A scintillator veto system completes the instrument. The commissioning of the HEPD and the other instruments on board is in progress and will last several months. In this contribution we will describe the HEPD detector and the (preliminary) performance in flight. Keywords: Detector techniques for Cosmology and Astroparticle Physics, Satellite experiment PACS: 29.40.Cs, 29.40.Gx 1. Introduction On February 2, 2018, the China Seismo-Electromagnetic Satellite (CSES) was launched successfully into a Sunsynchronous orbit with 97.4◦ inclination, a height of about 500 km and an ascending node of 14:00 local time. The scientific payloads include a search-coil magnetometer [1], an electric field detector [2], a high precision magnetometer [3], a GNSS Occultation receiver, a plasma analyzer, a Langmuir probe, an energetic particle detector [4] [5], and a three-frequency beacon. The main scientific goal of the mission is the real-time monitoring of electromagnetic changes of the Earth system, especially within the ionosphere. In particular, the satellite monitors the perturbations of the electromagnetic field, plasma and inner Van Allen belt particles in the ionosphere induced by natural sources with the aim to study their correlations with the occurrence of seismic events. ∗ Corresponding
author Email address: [email protected] (G. Osteria)
Preprint submitted to Elsevier
The high-energy particle detector of the CSES satellite, described in this article, has been designed for investigating seismo-induced particles perturbations. The particles trapped in the geomagnetic field lines of the Van Allen belts execute gyro-motion, bouncing and longitudinal drift according with their adiabatic invariants. They are sensitive to both solar terrestrial interactions and the internal electromagnetic emissions from the geomagnetic cavity. All these effects constitute a background in studying possible electromagnetic perturbations induced by lithospheric processes. Even though with extremely less efficacious effects, also the seismo-electromagnetic fluctuations occurring in space are capable to generate local perturbations of the inner Van Allen belt. Anomalous sharp increases of electron and proton counting rates (from a few MeV to several tens and hundreds of MeV) were detected mostly below the inner Van Allen radiation belt, near the South Atlantic anomaly (SAA), at altitudes of about 400 –1200 km, by several space experiments. The existence of a temporal correlation between these anomalous fluctuations, called particle bursts (PBs), and October 10, 2018
Figure 1: An overview of the High-Energy Particle Detector. Figure 2: HEPD installed on CSES
the occurrence of earthquakes of medium and strong magnitude have been suggested by several authors [6] and confirmed by data obtained on board of METEOR-3A and AUREOL-3 satellites [7] [8]. By measuring energy spectrum, direction and composition of particle fluxes, HEPD will study the stability of the inner Van Allen belts and particles precipitation trying to carefully discriminate anomalous events possibly induced by seismicity from the natural background, caused by geomagnetic, tropospheric and anthropogenic electromagnetic emissions. Another very important scientific objective of the HEPD is the study of the solar-terrestrial environment, as Coronal Mass Ejections (CMEs), Solar Energetic Particle (SEP) events and low-energy cosmic rays. The CSES mission will monitor the solar impulsive activity and the cosmic ray solar modulation by detecting proton and electron fluxes from a few MeV to hundreds MeV. These measurements will provide an extension down to very low energy of the range of the particle spectra obtained in the current 24th solar cycle by PAMELA and AMS experiments. Moreover, fluxes of light nuclei up to hundreds MeV/n will be provided.
• Veto system, consisting of 5 plastic scintillator counters, four lateral and one at the bottom of the instrument. All the scintillators (plastic and inorganic) are read out by photomultiplier tubes (PMT R9880-210 from Hamamatsu). The Electronics Subsystem [9] of the HEPD can be schematized into three blocks: Silicon detector, Scintillator detectors (trigger, energy and veto detectors), Global control and data managing. Each detector block includes power chain for bias distribution and a data acquisition processing chain. The main Power Supply provides the low voltages to the detector electronics and the high bias voltages for PMTs and silicon modules. The HEPD has mechanical dimensions of 530 × 382 × 404 mm3 , a mass of 45 kg and a power consumption of about 27 W in its default flight configuration. Rejection of particles hitting the lateral or bottom veto planes is performed online or offline by using different trigger commands. An electron/proton separation for fully contained events greater than 90% is achieved by the ∆EvsEtot method, where ∆E is obtained by the two layers of the silicon tracker, while Etot is measured by the calorimeter. Other main parameters of HEPD are:
2. The High Energy Particle Detector
Nuclei identification: up to oxygen; Energy resolution: < 10% ; Angular resolution: < 8◦ ; Field of view: 60◦ .
The High-Energy Particle Detector (HEPD) is designed to detect electrons in the energy range between 3 and 100 MeV, protons between 30 and 200 MeV and light nuclei. The detector is made up of several sub-detectors arranged as shown in Fig.1:
Following the standard procedures for space applications, four models of HEPD have been built and fully integrated in the clean rooms at the INFN laboratories of Roma Tor Vergata in Rome (Italy). The electrical model (EM), the structural and thermal model (STM), the qualification model (QM), and, fimally, the flight model (FM). The flight model was shipped to China, in December 2016. In January 2017, the functionality of the instrument was successfully tested standalone with its EGSE; then it was installed on the CSES satellite (Figure 2 ) in December 2017, HEPD has been transferred to the Jiuquan Satellite Launch Center, China, in the Gobi desert (Inner Mongolia) from where it has been launched, by a Long March 2D rocket, on the February 2nd, 2018.
• Tracker: two planes of double-side silicon micro-strip detectors are placed on the top of the detector in order to track the direction of the incident particle limiting the effect of Coulomb multiple scattering on the direction measurement; • Trigger: a layer of thin plastic scintillator, placed 10 mm below the tracker, divided into six segments (200 × 30 × 5 mm3 each) along the y direction; • Calorimeter: a tower of 16 layers of 1 cm thick plastic scintillator planes followed by a 3x3 matrix of an inorganic scintillator LYSO. 2
Figure 5: The comparison between proton beam data and MC simulation for dE/dx measurements (preliminary reults).
Figure 3: Energy loss by 30 MeV electrons within the upper segment of the HEPD calorimeter. The second and third peaks are produced by the pile-up of 2 or 3 simultaneous electrons.
Figure 6: HEPD calibration plot as function of energy (preliminary). Figure 4: Total energy loss in the HEPD calorimeter for 70 MeV protons. Sigma/peak = 0.08.
output and real data have the same format and the same software is used to reconstruct the event in both cases, allowing a fair comparison of reconstructed parameters and Monte Carlo truth. In Figure 5, a comparison between proton beam data and MC simulation for dE/dx measurements in a ladder of the HEPD silicon tracker is shown (preliminary results). The plot in Figure 6 summarizes the (preliminary) results of the calibration of the detector performed on ground by test beams and atmospheric muons.
3. HEPD calibration Calibrations of the QM and FM were performed by electron and proton beams. Electron tests took place at the Beam Test Facility (BTF) at the INFN Frascati National Laboratories. The parameters of the BTF were optimized to obtain beam bunches of low multiplicity electrons, for different energies: 30 MeV, 45 MeV, 60 MeV, 90 MeV and 120 MeV. Data collected were transmitted to the EGSE module that was controlled remotely from the control room, so emulating the satellite orbiting conditions. QM and FM were calibrated at different incident angles and positions. The total energy loss in the calorimeter for 30 MeV electrons is shown in Fig. 3. One, two or three electrons hitting the instrument in a single beam bunch are clearly visible. The proton test was performed on the FM at the Proton Therapy Center in Trento (Italy), where a cyclotron produces protons at energies ranging between 70 and 230 MeV. Energies below 70 MeV were obtained by using a degrader along the beam line. The detector was irradiated with protons at different energies between 37 and 228 MeV. Fig. 4 illustrates the total energy loss in the FM calorimeter for 70 MeV protons [10]. A full GEANT4 simulation of the apparatus was performed, accounting for detector response to all particles and reproducing readout electronics and trigger conditions. Monte Carlo
4. HEPD in-flight operation After the launch, the commissioning phase of the HEPD has been very intensive. On the 6th February 2018, the HEPD health check procedure was successfully run. The day after HEPD was tested in the framework of the satellite platform verification. The payload operated along 3 orbits. Since the 12th of February 2018 HEPD has been tested in different configurations in order to: • study the trigger rates along the orbit in different trigger configurations; • study to define the optimal trigger thresholds in flight; • perform an in-flight calibration to be compared with beam test results. 3
Figure 8: Raw trigger rate map. Figure 7: ADC counts (proportional to energy release) on a channel of the second plane of the energy sub-detector. The two arrows indicate the MIP and the proton peaks.
etc.). The wide energetic range allows studying several phenomena beyond the seismo-associated ones, such as those related to magnetospheric currents, dynamics of radiation belts and cosmic rays flux. During the foreseen five years of the mission, a large part of the 24th solar cycle will be monitored.
The commissioning activities are still in progress and will last until the end of July 2018. Since the beginning of May 2018 an encrypted data transfer from China (CEA-ICS) to Italy (ASI-SSDC) has been working. The data retrieval, processing and storage in Italy has been implemented in a two nodes infrastructure with a shared file system providing high availability and high resilience of the storage. A processing pipeline has been developed as several layers of software with an interface to a processing database and to the storage of the infrastructure. About 400 GB of raw data have been downloaded from HEPD up to now and partially processed by the pipeline. The HEPD status is monitored in quasi-real time by quicklook software to get immediate information (strips and PMTs ADC counts, rate and orbital zones, trigger rate, etc).
Acknowledgments This work was supported by the Italian Space Agency in the framework of the Accordo Attuativo n. 2016-16-H0 Progetto Limadou Fase E/Scienza (CUP F12F1600011005). References [1] Cao J B, Zeng L, Zan F, et al. The electromagnetic wave experiment for CSES mission: Search coil magnetometer. Sci China Tech Sci, 2018, 61:653-658, https://doi.org/10.1007/s11431-018-9241-7 [2] L. Alfonsi et al. The HEPD particle detector and the EFD electric field detector for the CSES satellite. Radiation Physics and Chemistry, 2017, 137: 187-192, https://doi.org/10.1016/j.radphyschem.2016.12.022 [3] Cheng B, Zhou B, et al. High precision magnetometer for geomagnetic exploration onboard of the China Seismo-Electromagnetic Satellite. Sci China Tech Sci, 2018, 61:659-668, https://doi.org/10.1007/s11431-0189247-6 [4] Ambrosi G, Bartocci S, Basara L, et al. The HEPD particle detector of the CSES satellite mission for investigating seismo-associated perturbations of the Van Allen belts. Sci China Tech Sci, 2018, 61: 643-652, https://doi.org/10.1007/s11431-018-9234-9 [5] Scotti V, Osteria G. The high energy particle detector onboard the CSES satellite, https://doi.org/10.1109/NSSMIC.2016.8069878 [6] Galper A M, Koldashov S V, Voronov S A. High energy particle flux variations as earthquake predictors. Adv Space Res, 1995, 15: 131-134, https://doi.org/10.1016/0273-1177(95)00085-S [7] Galperin Yu I, Gladyshev V A, Jordjio N V, et al. Precipitation of highenergy captured particles in the magnetosphere above epicenter of an incipient earthquake. Cosmic Res, 1992, 30: 89-106 [8] Pustovetov V P, Malyshev A V. Spatial-temporal correlation of the earthquakes and variations of high-energy particle flux in the inner radiation belt. Cosmic Res, 1993, 31: 84-87 [9] Scotti V, Osteria G. The electronics of the HEPD of the CSES experiment, Nuclear and Particle Physics Proceedings, 291-293: 118-121 https://doi.org/10.1016/j.nuclphysbps.2017.06.024 [10] Panico P, et al. Study on the High Energy Particle Detector calorimeter, PoS(ICRC2017)172 [11] Sauvaud J A, et al. High-energy electron detection onboard DEMETER: The IDP spectrometer, description and first results on the inner belt. Planetary and Space Science 2006, 54: 502-511, https://doi.org/10.1016/j.pss.2005.10.019 [12] Bakaldin A V, et al. Satellite experiment ARINA for studying seismic effects in the high-energy particle fluxes in the Earths magnetosphere. Cosmic Res, 2007, 45: 445-448, https://doi.org/10.1134/S0010952507050085
5. HEPD preliminary results A first data analysis has been carried out to compare flight data to ground acquired data: beam test and atmospheric muon data. A comparison with atmospheric muon data confirms (figure 7) that pedestals, as well as the MIP peak, are in the same position, confirming that the behaviour of the detector is not changed after the launch. A comparison with beam test data confirms that the region between 2000 and 4000 ADC counts is mainly associated to a proton contribution. Measured trigger rate has an important background contribution due to fragmentation products, off acceptance and rehentrant particles. Figure 8 shows the raw trigger rate map. 6. Conclusion The HEPD detector has been designed, built and fully tested for measuring electrons in the energy range between 3 and 100 MeV, protons between 30 and 200 MeV and light nuclei up to oxygen. The HEPD configuration represents a substantial improvement (for detector reliability, particle identification, energy range, pitches angle resolution, etc.) with respect to all particle detectors (with similar objectives and energy range) recently launched (such as IDP on Demeter [11], ARINA [12], 4
Research Highlights
Highlights: • • • •
Seismo-associated disturbances in the ionosphere-magnetosphere transition zone Simultaneous measurements of different parameters of the seismo-associated perturbations Satellite hosting on board a suite of advanced instruments to study such phenomena Charge particle detector to study precipitation of particle bursts in the ionosphere