Space Detection Research Articles

Proof of concept for through silicon vias in application-specific integrated circuits for hard x-ray imaging detectors

Application-specific integrated circuits (ASICs) are commonly used to efficiently process the signals from sensors and detectors in space. Wire bonding is a space-qualified technique of making interconnections between ASICs and their substrate packaging board for power, control, and readout of the ASICs. Wire bonding is nearly ubiquitous in modern space programs, but their exposed wires can be prone to damage during assembly and subject to electric interference during operations. Additional space around the ASICs needed for wire bonding also impedes efficient packaging of large arrays of detectors. Here, we introduce the through silicon vias (TSV) technology that replaces wire bonds and eliminates their shortcomings. We have successfully demonstrated the feasibility of implementing TSVs to existing ASIC wafers (a.k.a. a via-last process) developed for processing the x-ray signals from the x-ray imaging CdZnTe detectors on the Nuclear Spectroscopic Telescope Array small explorer telescope mission that was launched in 2012. While TSVs are common in the semiconductor industry, this is the first (to our knowledge) successful application for astrophysics imaging instrumentation. We expect that the TSV technology will simplify the detector assembly and thus will enable significant cost and schedule savings in assembly of large area CdZnTe detectors.

Dependence of the detected signal on the kinematic parameters of the satellite in the S-LIGO-E2R space system

The changes of distances less than ~10–21 are registered during the gravitational wave experiment. This feature determines the minimum size of experimental installations and the frequency range of gravitational wave detectors. To expand the frequency range and increase the sensitivity of gravitational interference detectors, it is necessary to increase the linear dimensions of the detector significantly as big as Earth and even more. The Republic of Belarus has experience in the development, launch and operation of satellites, the use of which can significantly increase the linear dimensions of the gravitational space detector. The satellite systems as a space detector of gravitational waves S-LIGO-NxR-zy are considered. The S-LIGO-NxR-zy space gravitational wave detector is a system of laser interferometers consisting of x number of satellites with given z-type orbits, in orbit of planet N of the solar system. The interferometers in such systems are identical to interferometers with oscillating mirrors due to the complex satellite motion. The purpose of this work is to study the influence of the kinematic parameters of satellites on the detected signal in the S-LIGO-E2R-z2 system. The configuration of the space detector determines the set of satellite orbits, direction and initial phase of movement. The detector signals depend on the instantaneous distance between the satellites and can be described as periodic functions. There are obtained the equations that describe the periodic changes in the signal between satellites as a result of their relative motion, depending on the initial conditions for launching the satellites. The general case for arbitrary oriented orbits and two special cases for collinear and orthogonal circular orbits in space gravitational wave detectors S-LIGO-E2R-z2-p and S-LIGO-E2R-z2-o are considered in the paper. The graphs of the dependences of the detected signal on the kinematic parameters of the satellites of the detectors S-LIGO-E2R-z2-p and S-LIGO-E2R-z2-o are presented. It is shown that the detected signals contain sections of zero intensity, and the duration and frequency of sections of zero intensity are related to the kinematic parameters of satellites.

Main results of the DAMPE space detector after 4 years in orbit

The DArk Matter Particle Explorer (DAMPE) is a high-performance space particle detector launched in orbit in 2015 by a collaboration of Chinese, Italian and Swiss scientific institutions, coordinated by the Chinese Academy of Sciences. It consists of a high-resolution segmented BGO electromagnetic calorimeter with a depth of 32 radiation lengths, a silicon-tungsten tracker-converter with an angular resolution below [Formula: see text], an anti-coincidence shield and ion detector, and a neutron detector. The detector characteristics and performance, and the latest observations of cosmic electrons up to 5 TeV, protons and nuclei up to 100 TeV and gamma-rays up to 10 TeV are presented.

Constraining gravitational-wave polarizations with Taiji

Space-based gravitational-wave detectors consist of a triangle of three spacecraft, which makes it possible to detect polarization modes of gravitational waves due to the motion of the detectors in space. In this paper we explore the ability of Taiji to detect the polarization modes in the parametrized post-Einsteinian framework. Assuming massive black hole binaries with the total mass of $M=4\times10^5\,M_{\odot}$ at redshift of $z=1$, we find that Taiji can measure the dipole and quadruple emission ($\Delta\alpha_D/\alpha_D$ and $\Delta\alpha_Q/\alpha_Q$) with the accuracy of up to $\sim 0.04\%$, with the fiducial value of $\alpha_D=0.001$, the scalar transverse and longitudinal modes ($\Delta\alpha_B$ and $\Delta\alpha_L$) up to $\sim 0.01$, and the vector modes ($\Delta\alpha_V$) up to $\sim 0.0005$.

Lensed gravitational waves: Scattering and applications

<p indent="0mm">The direct detection of gravitational waves from stellar-mass compact binary merger by ground-based laser interferometer gravitational wave detector LIGO/Virgo has verified the prediction of general relativity and opened a new chapter in gravitational wave astronomy. Up to now, a total of 50 gravitational wave events have been detected and published in GWTC-1 and GWTC-2 catalogue. In the near future, the third-generation ground based gravitational wave detector, such as the Einstein Telescope (ET), will be constructed with sensitivity improved by at least a factor of 10. Tens of thousands of gravitational wave signals are expected to be detected per year in the third-generation detector era. These gravitational wave signals will inevitably overlap with foreground massive celestial bodies (such as black hole, galaxy and galaxy cluster), thus leading to lensed gravitational wave signals which will undoubtedly be another important test of general relativity once detected. Furthermore, strongly lensed gravitational wave signals by galaxy from massive binary black hole could possibly be detected by future space detector, e.g., LISA and DECIGO. Since the wavelengths of gravitational waves are comparable with the size of some lens, the lensed gravitational waves play a unique role in studying the phenomena of wave nature, e.g., interference and diffraction. Lensed gravitational wave-electromagnetic wave system will have a wide range of applications in fundamental physics, cosmology and astrophysics when a series of lensed gravitational wave events and their corresponding electromagnetic counterparts have been detected. The most obvious advantage of lensed gravitational wave-electromagnetic wave system lies in that gravitational wave could provide time delay information with high accuracy, and electromagnetic wave could provide Fermat potential difference with high precision because a relatively complete arc of light could be obtained by electromagnetic wave observations and this is the most important step in measuring the Fermat potential. Thus, by combining the information from both approaches, lensed gravitational wave-electromagnetic wave system could be applied to study the speed of gravitational waves, constrain cosmological parameters, explore the substructure of the dark matter halo and investigate the lens model and so on. In this paper, we will review in detail how to use geodesic equation, lens equation, as well as wave equation to tackle the stationary scattering problem of lensed gravitational waves, and introduce how lensed gravitational wave-electromagnetic wave system could be applied to study the tensor properties, interference and diffraction effects of gravitational wave, as well as its applications in gravitational wave velocity, Hubble constant, cosmic curvature, lens mass, substructure and so on.

Measuring Parity Asymmetry of Gravitational Wave Backgrounds with a Heliocentric Detector Network in the mHz Band.

We discuss exploration for isotropic gravitational wave backgrounds around 1mHz by correlation analysis, targeting both parity odd and even polarization modes. Even though the space interferometer LISA alone cannot probe the two modes due to cancellations, the outlook is being changed drastically by the strong development of other space detectors such as Taiji. In fact, a heliocentric interferometer network can hold a preferable geometrical symmetry illuminated by a virtual sphere off-center from the Sun. By utilizing an internal symmetry of data streams, we can optimally decompose the odd and even parity modes at the correlation analysis. By simultaneously using LISA and Taiji for ten years, our sensitivity to the two modes could reach ∼10^{-12} in terms of the normalized energy density.

Ephemeris error correction in celestial navigation system considering Earth’s precession-nutation

Navigation systems are crucial space detector components. Advancements in optical equipment have made the Celestial Navigation System (CNS) continually more accessible. Ephemeris error, however, limits the CNS navigation accuracy. This paper proposes an autonomous CNS equipped with an ephemeris error correction model. The model provides the navigation stars’ high-accuracy ephemeris information for navigation stars based on the coupled effects of the Earth’s nutation and precession; this allows for effective positioning and attitude determination of space detector. The navigation star ephemeris errors under the proposed method are significantly improved compared to the traditional Smithsonian Astrophysical Observatory (SAO) star catalog recorded on January 1, 2000. The proposed method also shows more accurate space detector attitude and positioning estimations compared to another existing ephemeris error correction method. The proposed method can be effectively applied to high-accuracy attitude and position estimation.

Performance characteristics and validation of alpha particle spectrometers for radiometric analysis of natural and anthropogenic radionuclides of environmental impacts

Alpha spectrometry is one of the greatest nuclear techniques for identification and quantification of α-emitters in the environment due to nuclear fuel cycle operations, nuclear materials and geochemical studies or forensic medicine investigations. This study was conducted to re-evaluate and optimize the factors affecting the performance of a multi-chamber alpha spectrometer (EG&G Ortec) used in our laboratory using an aged α-source of 232U in equilibrium with its decay products. The results shown that the energy calibration within energy window 4–9 MeV has been done using alpha particle emissions of 232U (t1/2.70.6 y) and its decay products with good linear fitting (R2 > 0.999). At a source to detector spacing of 10 mm, the efficiency of the detectors varied between 15 and 20%; while the better resolution (FWHM) was ~36 keV. These values are lower than those warranted when supplied before 20 years. The minimum detectable activity (MDA) of the detectors varies between 0.8 and 3.1 mBq for the chamber in use. The alpha spectrometer was also verified by certified reference samples to measure activity concentration of alpha emitters (e.g., 238U, 232Th, 226Ra and 241Am) with acceptable coefficient of variance (<10%), ζ-score (<3) and P-test (<25%). As a result, the optimized alpha spectrometer is valid and can be utilized for monitoring and assessment of natural and artificial α-emitters in different environmental compartments.

Cosmic ray spectrum from 250 TeV to 10 PeV using IceTop

We report here an extension of the measurement of the all-particle cosmic-ray spectrum with IceTop to lower energy. The new measurement gives full coverage of the knee region of the spectrum and reduces the gap in energy between previous IceTop and direct measurements. With a new trigger that selects events in closely spaced detectors in the center of the array, the IceTop energy threshold is lowered by almost an order of magnitude below its previous threshold of 2 PeV. In this paper, we explain how the new trigger is implemented, and we describe the new machine-learning method developed to deal with events with very few detectors hit. We compare the results with previous measurements by IceTop and others that overlap at higher energy and with HAWC and Tibet in the 100 TeV range.

Radiation damage assessment of SensL SiPMs

Silicon Photomultipliers (SiPMs) are quickly replacing traditional photomultiplier tubes (PMTs) as the readout of choice for gamma-ray scintillation detectors in space. While they offer substantial size, weight and power saving, they have shown to be susceptible to radiation damage. SensL SiPMs with different cell sizes were irradiated with 64 MeV protons and 8 MeV electrons. In general, results show larger cell sizes were more susceptible to radiation damage with the largest 50μm SiPMs showing the greatest increase in current as a function of dose. Current increases were observed for doses as low at ∼2 rad(Si) for protons and ∼20 rad(Si) for electrons. The U.S. Naval Research Laboratory’s (NRL) Strontium Iodide Radiation Instrument (SIRI-1) experienced a 528μA increase in the bias current of the onboard 2x2 SensL J-series 60035 SiPM over its one-year mission in sun-synchronous orbit. The work here focuses on the increase in bulk current observed with increasing radiation damage and was performed to better quantify this effect as a function of dose for future mission. These include the future NRL mission SIRI-2, the follow on to SIRI-1, Glowbug and the GAGG Radiation Instrument (GARI).

Cover Picture

Cryo‐electron diffraction tomography (Cryo‐EDT) has been developed to determine the crystal structures of covalent organic frameworks (COFs) and their host‐guest interaction at the atomic precision, whose crystals are only submicron‐sized, organic, porous, and dynamic. The keys of 3D electron diffraction (3D‐ED) techniques are low‐dose beam, sample cryo‐handling, fast data collection, sensitive detector, and direct space structure solution. We envision the development of COF chemistry will be propelled by such powerful 3D‐ED techniques for a better understanding at the molecular level and correlation of structures to chemicophysical properties. More details are discussed in the article by Zhang et al. on page 1153—1166.image

Gravitational waves from SGRs and AXPs as fast-spinning white dwarfs

ABSTRACT In our previous article we have explored the continuous gravitational waves (GWs) emitted from rotating magnetized white dwarfs (WDs) and their detectability by the planned GW detectors such as Laser Interferometer Space Antenna (LISA), Deci-hertz Interferometer Gravitational wave Observatory (DECIGO), and Big Bang Observer (BBO). Here, GWs’ emission due to magnetic deformation mechanism is applied for soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs), described as fast-spinning and magnetized WDs. Such emission is caused by the asymmetry around the rotation axis of the star generated by its own intense magnetic field. Thus, for the first time in the literature, the GW counterparts for SGRs/AXPs are described as WD pulsars. We find that some SGRs/AXPs can be observed by the space detectors BBO and DECIGO. In particular, 1E 1547.0−5408 and SGR 1806−20 could be detected in 1 yr of observation, whereas SGR 1900+14, CXOU J171405.7−381031, Swift J1834.9−0846, SGR 1627−41, PSR J1622−4950, SGR J1745−2900, and SGR 1935+2154 could be observed with a 5-yr observation time. The sources XTE J1810−197, SGR 0501+4516, and 1E 1048.1−5937 could also be seen by BBO and DECIGO if these objects have $M_{\mathrm{ WD}} \lesssim 1.3 \, \mathrm{M}_{\odot }$ and $M_{\mathrm{ WD}} \lesssim 1.2 \, \mathrm{M}_{\odot }$, respectively. We also found that SGRs/AXPs as highly magnetized neutron stars are far below the sensitivity curves of BBO and DECIGO. This result indicates that a possible detection of continuous GWs originated from these objects would corroborate the WD pulsar model.

Patient-specific dose quality assurance of single-isocenter multiple brain metastasis stereotactic radiosurgery using PTW Octavius 4D.

PurposeSingle‐isocenter multiple brain metastasis stereotactic radiosurgery is an efficient treatment modality increasing in clinical practice. The need to provide accurate, patient‐specific quality assurance (QA) for these plans is met by several options. This study reviews some of these options and explores the use of the Octavius 4D as a solution for patient‐specific plan quality assurance.MethodsThe Octavius 4D Modular Phantom (O4D) with the 1000 SRS array was evaluated in this study. The array consists of 977 liquid‐filled ion chambers. The center 5.5 cm × 5.5 cm area has a detector spacing of 2.5 mm. The ability of the O4D to reconstruct three‐dimensional (3D) dose was validated against a 3D gel dosimeter, ion chamber, and film measurements. After validation, 15 patients with 2–11 targets had their plans delivered to the phantom. The criteria used for the gamma calculation was 3%/1 mm. The portion of targets which were measurable by the phantom was countable. The accompanying software compiled the measured doses allowing each target to be counted from the measured dose distribution.ResultsSpatial resolution was sufficient to verify the high dose distributions characteristic of SRS. Amongst the 15 patients there were 74 targets. Of the 74 targets, 61 (82%) of them were visible on the measured dose distribution. The average gamma passing rate was 99.3% (with sample standard deviation of 0.68%).ConclusionsThe high resolution provided by the O4D with 1000 SRS board insert allows for very high‐resolution measurement. This high resolution in turn can allow for high gamma passing rates. The O4D with the 1000 SRS array is an acceptable method of performing quality assurance for single‐isocenter multiple brain metastasis SRS.

Research Progress of Thermal Contact Resistance

Thermal contact resistance of solid–solid interface is involved in many fields such as aerospace, low-temperature superconductivity and electronic machinery. With the booming of aerospace technology, the requirements for space detectors continue to increase; the research on accurate prediction, measurement and utilization of thermal contact resistance is becoming increasingly serious. This article systematically summarizes and analyzes the research progress of thermal contact resistance. It also comparatively analyzes theoretical prediction models, steady-state and transient-state experimental methods and numerical analysis methods from different angles, and summarizes the advantages and disadvantages of different methods. Moreover, the effects of the influencing factors such as the physical properties, the surface state, the contact pressure, the contact temperature, the heat flux direction and the thermal interface materials on the solid–solid thermal contact resistance are also briefly described. Through this systematic comparative analysis, further development directions are pointed out.

Dark Matter searches: an overview

The INFIERI school aims at presenting some of the most exciting frontiers of physics and technology. The matter we know (baryonic matter made with protons, neutrons and electrons) is less than 5% of the energy content, and the Universe is dominated today by unknown Dark Energy (DE) and Dark Matter (DM). The existence of DM is now a mainstream concept, although at galactic scales all evidence for DM can also be explained by models with modified gravity. Evidence at large scales are however hard to reconcile with a simple modified gravity model. Cosmological Microwave Background (CMB) measurements show evidence for non-baryonic DM, which cannot be explained by the no-DM modified gravity models. Large scale N-body simulations prefer Cold Dark Matter (CDM) to Hot Dark Matter (HDM), Cold/Hot designating non-relativistic vs relativistic particles at decoupling, but the nature of DM is still unknown and many hypothesis have been suggested and explored. Some extensions of the Standard Model of Particle Physics expect particles which are neutral and interact very weakly with other forms of matter (WIMPs) In this short lecture notes, which is not aimed as a review of the field, I will summarize what is known about the existence of DM, which lead us to develop the most sensitive detectors in space, on Earth, and in underground laboratories. I will focus mainly on the Direct Detection of WIMPS and some of the experimental challenges. As the 2019 INFIERI school was held in Wuhan, China, I have mainly selected examples from the Chinese projects.

AGILESim: Monte Carlo Simulation of the AGILE Gamma-Ray Telescope

Abstract The accuracy of Monte Carlo simulations in reproducing the scientific performance of space telescopes (e.g., angular resolution) is mandatory for a correct design of the mission. A brand-new Monte Carlo simulator of the Astrorivelatore Gamma ad Immagini LEggero (AGILE)/Gamma-Ray Imaging Detector (GRID) space telescope, AGILESim, is built using the customizable Bologna Geant4 Multi-Mission Simulator (BoGEMMS) architecture and the latest Geant4 library to reproduce the instrument performance of the AGILE/GRID instrument. The Monte Carlo simulation output is digitized in the BoGEMMS postprocessing pipeline, according to the instrument electronic readout logic, then converted into the onboard data handling format, and finally analyzed by the standard mission on-ground reconstruction pipeline, including the Kalman filter, as a real observation in space. In this paper we focus on the scientific validation of AGILESim, performed by reproducing (i) the conversion efficiency of the tracker planes, (ii) the tracker charge readout distribution measured by the on-ground assembly, integration, and verification activity, and (iii) the point-spread function of in-flight observations of the Vela pulsar in the 100 MeV–1 GeV energy range. We measure an in-flight angular resolution (full width at half-maximum) for Vela-like point sources of and in the 100–300 and 300–1000 MeV energy bands, respectively. The successful cross-comparison of the simulation results with the AGILE on-ground and in-space performance validates the BoGEMMS framework for its application to future gamma-ray trackers (e.g., e-ASTROGAM and AMEGO).

Space application: The AMS RICH

A Ring Imaging Cherenkov detector is on board the Alpha Magnetic Spectrometer, for mass and charge identification of charged cosmic rays. AMS is a high-energy particle physics magnetic spectrometer in space, which was successfully installed at the International Space Station on May 2011 to perform accurate measurements of Galactic Cosmic Rays fluxes in the rigidity range from 1 GV to a few TV. The RICH detector provides AMS the capability to measure the light nuclei isotopic composition of CRs, in the kinetic energy range from a few GeV/nucleon to about 10 GeV/nucleon, so far largely uncovered by previous experiment. In addition, the RICH is a key detector in indirect search for Dark Matter looking at the antiproton and anti-deuteron rare species.The detector has shown stable response during the past 8 years of continuous data taking and no significant indication of degradation has been observed. Once accounted for the extreme environmental conditions of the detector in space and their variation in time, the performances in velocity end charge measurements match the requirements. The different stages of the AMS-RICH construction, from design to commissioning through space qualification and characterization tests, are addressed in this paper, in the aim of highlighting the important aspects which contributed to the success of this detector, only of its kind operative in a long duration mission in space.

Possible detection of solar gamma-rays by ground-level detectors in solar flares on 2011 March 7

Abstract On 2011 March 7, the Solar Neutron Telescope located at Mt. Sierra Negra, Mexico (4600 m) observed enhancements of the counting rate from 19:57 to 20:04 UT with statistical significance 6.8σ and from 20:36 to 21:03 UT with 5.8σ. One plausible physical explanation for the observation enhancements is that they were produced by solar gamma-rays. The intensities were estimated to be (0.16 ± 0.03) photons cm−2 s−1 for the first flare and (0.22 ± 0.04) photons cm−2 s−1 for the second one at the top of the atmosphere. As far as we know, this is the first report on the detection of solar gamma-rays with a ground-based detector. In association with these events, the solar neutron detector Space Environment Data Acquisition Equipment on board the International Space Station registered two solar neutrons with statistical significances of 7.3σ and 6.6σ. The Large Area Telescope on board the Fermi observatory also observed high-energy gamma-rays from this flare with a statistical significance of 6.7σ. In this paper we propose a unified model to explain the production mechanism of high-energy gamma-rays and neutrons in association with this flare.

Thermodynamic analysis of the working states of the Stirling/pulse tube hybrid cryocooler

The Stirling/pulse tube hybrid cryocooler (SPC) is a kind of high efficiency multi-stage cryocooler which has the potential to be a competitive candidate in space detector cooling. This kind of hybrid cryocooler exhibits special thermodynamic characteristics that have significant influence on the performance and the working state of the Stirling stage of the SPC could be different from normal Stirling cryocooler.Focus on different working states of the Stirling stage of the SPC, a thermodynamic model is established. Altogether five working states of the Stirling stage are classified into two main types according to whether the phase shifter of the pulse tube stage is precooled by the Stirling stage. The detailed study indicates that the working states are closely related to the movement of the piston and the displacer. The criteria including both the swept volume ratio and the phase angle difference of the piston and the displacer for each working state are obtained. The boundaries between different working states are also presented. A non-dimensional parameter G is proposed to identify the working state. Theoretical results are compared with both the numerical simulation and the experiment and good agreement is achieved. This study will be of great significance to the proper design and optimization of the Stirling/pulse tube hybrid cryocooler.

Gravitational waves from fast-spinning white dwarfs

ABSTRACT Two mechanisms of gravitational waves (GWs) emission in fast-spinning white dwarfs (WDs) are investigated: accretion of matter and magnetic deformation. In both cases, the GW emission is generated by an asymmetry around the rotation axis of the star. However, in the first case, the asymmetry is due to the amount of accreted matter on the magnetic poles, while in the second case it is due to the intense magnetic field. We have estimated the GW amplitude and luminosity for three binary systems that have a fast-spinning magnetized WD, namely, AE Aquarii, AR Scorpii, and RX J0648.0−4418. We find that, for the first mechanism, the systems AE Aquarii and RX J0648.0−4418 can be observed by the space detectors BBO and DECIGO if they have an amount of accreted mass of δm ≥ 10−5 M⊙. For the second mechanism, the three systems studied require that the WD have a magnetic field above ∼109 G to emit GWs that can be detected by BBO. We also verified that, in both mechanisms, the gravitational luminosity has an irrelevant contribution to the spin-down luminosity of these three systems. Therefore, other mechanisms of energy emission are needed to explain the spin-down of these objects.