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Multi-messenger observations of the transient sky to detect cosmic explosions and counterparts of gravitational wave mergers critically rely on orbiting wide-FoV telescopes to cover the wide range of wavelengths where atmospheric absorption and emission limit the use of ground facilities. Thanks to continuing technological improvements, miniaturised space instruments operating as distributed-aperture constellations are offering new capabilities for the study of high energy transients to complement ageing existing satellites. In this paper we characterise the performance of the upcoming joint SpIRIT + HERMES-TP/SP nano-satellite constellation for the localisation of high-energy transients through triangulation of signal arrival times. SpIRIT is an Australian technology and science demonstrator satellite designed to operate in a low-Earth Sun-synchronous Polar orbit that will augment the science operations for the equatorial HERMES-TP/SP. In this work we simulate the improvement to the localisation capabilities of the HERMES-TP/SP when SpIRIT is included in an orbital plane nearly perpendicular (inclination = 97.6$^\circ$) to the HERMES orbits. For the fraction of GRBs detected by three of the HERMES satellites plus SpIRIT, the combined constellation is capable of localising 60% of long GRBs to within ~ 30 deg$^2$ on the sky, and 60% of short GRBs within ~ 1850 deg$^2$. Based purely on statistical GRB localisation capabilities (i.e., excluding systematic uncertainties and sky coverage), these figures for long GRBs are comparable to those reported by the Fermi GBM. Further improvements by a factor of 2 (or 4) can be achieved by launching an additional 4 (or 6) SpIRIT-like satellites into a Polar orbit, which would both increase the fraction of sky covered by multiple satellite elements, and enable $\geq$ 60% of long GRBs to be localised within a radius of ~ 1.5$^\circ$ on the sky., 17 pages, 10 figures, 1 table. Accepted for publication in PASA

The ORION chipset, a full-custom multi-chip readout and processing electronics for the X-γ Imaging Spectrometer (XGIS) on-board the THESEUS space mission, is presented. The XGIS detection plane is arranged in a matrix of 10×10 detection modules, each one composed by 64 CsI(Tl) scintillation bars (4.5 mm×4.5 mm×30 mm) optically coupled at the top and bottom ends to two 8×8 monolithic Silicon Drift Detector matrices. The top SDD, exposed to the X-ray entrance window, performs the double function of low-energy X-ray detection as well as scintillator’s readout, together with the bottom SDD, providing a detection and spectroscopic energy range from 2 keV up to 20 MeV. The need to achieve a high energy resolution, as well as a high sensitive area on the detection plane, led to the development of a chipset organized to have a minimum-area analog readout chip placed in close proximity of the SDD (ORION-FE) and a mixed-signal back-end (ORION-BE) placed a few centimeters further on the back-end board for the additional signal processing and digitization. The multi-chip readout electronics integrates two dedicated analog processors for low-energy photons up to 30 keV (X-processor) and high-energy photons up to 5 MeV (γ-processor), allowing a spectroscopy-grade resolution in the 4 decades energy band (2 keV–20 MeV) of the XGIS, with a simulated power consumption of 1.55 mW/pixel. The ORION prototype was bonded to two ~25mm2 SDDs, and extensively characterized in terms of pulse shaping, pulse discrimination and stretching functionality, as well as linearity, dynamic range and spectroscopic resolution. An optimum Equivalent Noise Charge (ENC) at –20°C of 24.3 el. r.m.s. on the X-channel (212 eV FWHM on Si), and 39.6 el. r.m.s. on the γ-channel (3.7 keV FWHM on CsI(Tl)) has been recorded.

This paper presents the front-end section of the X-/γ-ray detection instrument of the HERMES mission, whose goal is to observe and localize γ-ray bursts, through a constellation of more than one hundred nano-satellites. Considering the severe volume and power consumption constraints of the nano-satellites, in the HERMES X-/γ-ray detection instrument, silicon drift detectors are read out through a mixed-signal ASIC chipset, called LYRA, based on a peculiar architecture. In particular, a small front-end ASIC (LYRA-FE), placed close to each silicon drift detector, is connected, through a current-mode link, to a multi-channel back-end ASIC (LYRA-BE). The LYRA ASIC chipset, implemented in a 0.35µm CMOS technology, achieves less than $22{\text{e}}_{{\text{rms}}}^ - $ of equivalent noise charge, with a power consumption lower than 600µW/channel from a 3.3V power supply. Thanks to the current-mode link between the LYRA-FE and the LYRA-BE ASICs, no significant crosstalk among channels can be observed, in spite of the length of the interconnection wires as large as 12cm.

The HERMES-TP/SP mission, based on a nanosatellite constellation, has very stringent constraints of sensitivity and compactness, and requires an innovative wide energy range instrument. The instrument technology is based on the "siswich" concept, in which custom-designed, low-noise Silicon Drift Detectors are used to simultaneously detect soft X-rays and to readout the optical light produced by the interaction of higher energy photons in GAGG:Ce scintillators. To preserve the inherent excellent spectroscopic performances of SDDs, advanced readout electronics is necessary. In this paper, the HERMES detector architecture concept will be described in detail, as well as the specifically developed front-end ASICs (LYRA-FE and LYRA-BE) and integration solutions. The experimental performance of the integrated system composed by scintillator+SDD+LYRA ASIC will be discussed, demonstrating that the requirements of a wide energy range sensitivity, from 2 keV up to 2 MeV, are met in a compact instrument., Comment: 12 pages, 10 figures. Proceedings of SPIE "Astronomical Telescopes and Instrumentation" 2020

Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray; Virtual, Online; United States; 14 December 2020 through 18 December 2020; Code 166330.--Proceedings of SPIE - The International Society for Optical Engineering Volume 11444, 2020, Article number 114442K.--Full list of authors: Labanti, C.; Amati, L.; Frontera, F.; Mereghetti, S.; Gasent-Blesa, J. L.; Tenzer, C.; Orleanski, P.; Kuvvetli, I.; Campana, R.; Fuschino, F.; Terenzi, L.; Virgilli, E.; Morgante, G.; Orlandini, M.; Butler, R. C.; Stephen, J. B.; Auricchio, N.; De Rosa, A.; Da Ronco, V.; Evangelisti, F. Melchiorri, M.; Squerzanti, S.; Fiorini, M.; Bertuccio, G.; Mele, F.; Gandola, M.; Malcovati, P.; Grassi, M.; Bellutti, P.; Borghi, G.; Ficorella, F.; Picciotto, A.; Zanini, V.; Zorzi, N.; Demenev, E.; Rashevskaya, I.; Rachevski, A.; Zampa, G.; Vacchi, A.; Zampa, N.; Baldazzi, G.; La Rosa, G.; Sottile, G.; Volpe, A.; Winkler, M.; Reglero, V.; Connell, P. H.; Pinazo-Herrero, B.; Navarro-González, J.; Rodríguez-Martínez, P.; Castro-Tirado, A. J.; Santangelo, A.; Hedderman, P.; Lorenzi, P.; Sarra, P.; Pedersen, S. M.; Tcherniak, D.; Guidorzi, C.; Rosati, P.; Trois, A.; Piazzolla, R., THESEUS (Transient High Energy Sky and Early Universe Surveyor) is one of the three missions selected by ESA as fifth medium class mission (M5) candidates in its Cosmic Vision science program, currently under assessment in a phase A study with a planned launch date in 2032. THESEUS is designed to carry on-board two wide and deep sky monitoring instruments for X/gamma-ray transients detection: a wide-field soft X-ray monitor with imaging capability (Soft X-ray Imager, SXI, 0.3 - 5 keV), a hard X-ray, partially-imaging spectroscopic instrument (X and Gamma Imaging Spectrometer, XGIS, 2 keV - 10 MeV), and an optical/near-IR telescope with both imaging and spectroscopic capability (InfraRed Telescope, IRT, 0.7 - 1.8 µm). The spacecraft will be capable of performing fast repointing of the IRT to the error region provided by the monitors, thus allowing it to detect and localize the transient sources down to a few arcsec accuracy, for immediate identification and redshift determination. The prime goal of the XGIS will be to detect transient sources, with monitoring timescales down to milliseconds, both independently of, or following up, SXI detections, and identify the sources performing localisation at, The Phase A study of the THESEUS/XGIS instrument is supported by ASI-INAF Agreement n. 2018-29-HH.0, OHB Italia/ - INAF-OASBo Agreement n.2331/2020/01, by the European Space Agency ESA through the M5/NPMC Programme and by the AHEAD2020 project funded by UE through H2020-INFRAIA-2018-2020. By the Spanish Ministerio de Ciencia e Innovación, PID2019-109269RB-C41. By Polish National Science Center, Project 2019/35/B/ST9/03944 and Foundation for Polish Science, Project POIR.04.04.00-00-5C65/17-00.

Silicon carbide is a well-known material with high thermal, mechanical and chemical stability. These properties have allowed, over time, its wide use as an inert material to be employed as a substrate or support in different applications. In this work, we demonstrate that, under proper conditions, it is possible to activate the chemical reactivity of nanostructured SiC, which can be employed for chemoresistive purposes. With this aim, a commercial powder of SiC has been characterized from a morphological, structural and thermal point of view. Then, screen–printed thick films were obtained from SiC powder and thus tested as a functional material for chemoresistive gas sensors, in thermo-activation mode. The samples were exposed to 13 gases with important chemical differences. Analyses showed that SiC is an extremely selective functional material for the detection of sulphur dioxide (SO2) in concentrations within the ppm range. This interesting result was found at high working temperatures (600−800 °C), useful for harsh environments, and the measurements proved to be completely free from humidity negative interference. Thermo-gravimetric and X-ray photoelectron spectroscopy characterizations highlighted that the high selectivity of the SiC layer is promoted by the thermal formation of a SiC/SiOC core-shell, tunable by controlling temperature and humidity parameters. An interpretation of the gas sensing mechanism occurring between SO2 molecules and SiC/SiOC core-shell has been proposed. The unexpected chemical activity, identified for nanostructured SiC, can be exploited for the specific detection of SO2, since this gaseous compound plays an important role in air pollution, industrial processes and winemaking.

We present the design and characterization of a detection unit for simultaneous and combined XRF and XRD analysis of powder mineralogical samples. Arrays of 32 silicon microstrips are coupled to two 16-channel CUBE preamplifiers targeting an energy resolution below 200 eV at 6 keV with moderate cooling. The compact detection module will be mounted on a goniometer inside a suitcase-sized analyzer to be operated in mining sites.

Ion beam sputtering can induce the formation of regular self-assembled surface nanostructures on different materials. Several experimental variables, such as the ion energy, the ion incidence angle, the ion fluence, together with the sample surface properties and temperature, have been proven to control in a complex and not completely codified manner the formation of periodically arranged dot, hole or ripple nanopatterns. In this work, we have studied how to apply ion beam sputtering to induce periodic ripples of specific aspect ratio on silicon surfaces, namely ripple height a of about 10nm and period λź50nm, since these topographies can be appealing for technological applications. Silicon surfaces were irradiated with increasing O+ and Xe+ ion fluences at fixed ion energy and incidence angle. We have verified that some combinations of the chosen parameter values produced the desired structures. The obtained results also indicate that with a further refinement of those parameter values a better control of the aspect ratio of the obtained ripples is possible. Therefore, this work is a contribution to the final aim of exploiting ion beam sputtering as a fast, cost-effective and single-step method to fabricate well-controlled patterns over large surface areas at length scales beyond those of both standard and e-beam lithography. Display Omitted An empirical recipe has been provided to obtain nano-ripples of desired height a and wavelength λ by ion beam sputtering.The ion species, energy, incidence angle, and dose have been varied to fabricate ripples on Si of aspect ratio a/λź1/5.Through AFM and SEM analysis, the limits about the effective tuning of the ripple feature sizes have been discussed.Some of the obtained structures can potentially be used in plasmonics, electrochemical devices and bio-devices.

This work presents a study of application of secondary ion mass spectrometry (SIMS) to measure tin concentration in Ge 1− x Sn x alloy with x higher than solid solubility ∼1%, i.e. well above the diluted regime where SIMS measurements usually provide the most reliable quantitative results. SIMS analysis was performed on Sn + ion implanted Ge films, epitaxially deposited on Si, and on chemical vapor deposition deposited Ge 0.93 Sn 0.07 alloy. Three SIMS conditions were investigated, varying primary beam ion species and secondary ion polarity keeping 1 keV impact energy. Best depth profile accuracy, best agreement with the fluences measured by Rutherford backscattering spectrometry, good detection limit (∼1 × 10 17 at/cm 3 ) and depth resolution (∼2 nm/decade) are achieved in Cs + /SnCs + configuration. However, applied sputtering conditions (Cs + 1 keV, 64° incidence vs. normal) induced an early formation of surface topography on the crater bottom resulting in significant variation of sputtering yield. Atomic force microscopy shows a peculiar topography developed on Ge: for oblique incidence, a topography consisting in a sequence of dots and ripples was observed on the crater bottom. This behavior is unusual for grazing incidence and has been observed to increase with the Cs + fluence. Rotating sample during sputtering prevents this ripple formation and consequently improves the depth accuracy.

In very recent years particular effort is being devoted to the development of radiofrequency (rf) pulsed glow discharges (GDs) coupled to time of flight mass spectrometry (ToFMS) for depth profile qualitative analysis with nanometre depth resolution of technological materials. As such technique does not require sampling at ultra-high vacuum conditions it facilitates a comparatively high sample throughput, related to the reference technique secondary ion mass spectrometry (SIMS). In this work, pulsed rf-GD-ToFMS is investigated for the fast and sensitive characterization of boron and arsenic ultra low energy (ULE) implants on silicon. The possibility of using a simple multi-matrix calibration procedure is demonstrated for the first time for quantification of this type of samples and the validation of the proposed procedure has been carried out through the successful analysis of a multilayered sample with single and couple 11B delta markers. Results obtained with the proposed methodology for boron and arsenic ULE implants, prepared under different ion doses and ion energy conditions, have proved to be in good agreement with those achieved by using complementary techniques including SIMS and grazing incidence X-ray fluorescence. Thus, although further investigations are necessary for more critical evaluation of depth resolution, the work carried out demonstrates that rf-GD-ToFMS can be an advantageous tool for the analytical characterization of boron and arsenic ULE implants on silicon.

We have observed the influence of heat flux on the orientation of a nematic liquid crystal (NLC), which initially occurred in a homogeneously oriented state. The action of a spatially periodic heat flux leads to a change in the NLC director orientation, which is not accompanied by a hydrodynamic flow. The pattern observed in a polarized light resembles the system of bands that arises during the Freedericksz transition in a static spatially periodic electric field. It is concluded that the observed behavior is evidence for the existence of orientational thermoelasticity, which is determined by the quadratic dependence of the director deviation on the temperature gradient. The observation of this thermoorientational interaction contradicts the commonly accepted notions, according to which the director of a mirror-symmetric liquid crystal must be immobile.

The production of Ge1-xSnx alloy nano-structures through high fluence Sn ion implantation at room temperature and subsequent rapid thermal annealing was investigated. Implant energy was set at 45 keV, aiming to produce a

Secondary ion mass spectrometry (SIMS) and medium energy ion scattering (MEIS) have been applied to the characterization of ultra shallow distribution of arsenic in silicon obtained by ion implantation at 0.5–5 keV. MEIS offers the advantage of accurate quantification and ultimate depth resolution

In the last years a lot of effort has been directed in order to reduce ion implantation damage, which can be detrimental for silicon device performances. Implantation's dose rate and temperature were found to be two important factors to modulate residual damage left in silicon after anneal. In this work high dose rate, low temperature, high dose arsenic and boron implantations are compared to the corresponding low dose rate, room temperature processes in terms of silicon lattice defectiveness and dopant distribution, before and after anneal is performed. The considered implant processes are the one typically used to form a source/drain region in a CMOS process flow in the submicron technology node. A spike anneal process was applied to activate the dopant. Low temperature, high dose rate implantations have found to be effective in reducing silicon extended defects with a negligible effect on the profile of the activated dopant. Experimental set up, results and possible explanation will be reported and discussed in the paper.

The continuous downscaling of the process size for semiconductor devices pushes the junction depths and consequentially the implantation depths to the top few nanometers of the Si substrate. This motivates the need for sensitive methods capable of analyzing dopant distribution, total dose and possible impurities. X-ray techniques utilizing the external reflection of X-rays are very surface sensitive, hence providing a non-destructive tool for process analysis and control. X-ray reflectometry (XRR) is an established technique for the characterization of single- and multi-layered thin film structures with layer thicknesses in the nanometer range. XRR spectra are acquired by varying the incident angle in the grazing incidence regime while measuring the specular reflected X-ray beam. The shape of the resulting angle-dependent curve is correlated to changes of the electron density in the sample, but does not provide direct information on the presence or distribution of chemical elements in the sample. Grazing Incidence XRF (GIXRF) measures the X-ray fluorescence induced by an X-ray beam incident under grazing angles. The resulting angle dependent intensity curves are correlated to the depth distribution and mass density of the elements in the sample. GIXRF provides information on contaminations, total implanted dose and to some extent on the depth of the dopant distribution, but is ambiguous with regard to the exact distribution function. Both techniques use similar measurement procedures and data evaluation strategies, i.e. optimization of a sample model by fitting measured and calculated angle curves. Moreover, the applied sample models can be derived from the same physical properties, like atomic scattering/form factors and elemental concentrations; a simultaneous analysis is therefore a straightforward approach. This combined analysis in turn reduces the uncertainties of the individual techniques, allowing a determination of dose and depth profile of the implanted elements with drastically increased confidence level. Silicon wafers implanted with Arsenic at different implantation energies were measured by XRR and GIXRF using a combined, simultaneous measurement and data evaluation procedure. The data were processed using a self-developed software package (JGIXA), designed for simultaneous fitting of GIXRF and XRR data. The results were compared with depth profiles obtained by Secondary Ion Mass Spectrometry (SIMS)., Highlights • The parameter optimization by curve fitting uses differential evolution (an evolutionary algorithm). • Implantation profiles are modeled by using the Pearson distribution system. • The implant distribution profile is discretized to allow calculation similar to a layered sample. • Total implanted dose, implantation depth and profile shape can be determined nondestructively.

Samples produced by plasma immersion ion implantation of Arsenic in Silicon using a non-pulsed plasma source and subsequent laser annealing were investigated with respect to As depth distribution, oxide thickness, and As local order using SIMS, XPS, INAA and EXAFS analysis. A surface layer (∼10 nm), was identified as an As-rich Si oxide formed after implantation. The thickness of this layer was found to be larger for samples annealed using a low thermal budget up to a threshold where probably melting occurred. Dopant depth profile was re-distributed whereas the final oxide film of these samples showed thicknesses of a few nm. The retained As dose exhibited an apparent drastic increase. A hypothesis for the processes involved is presented based on experimental evidence.

The behavior of ultra shallow ion implants of arsenic in Si following solid phase epitaxial re-growth process is reported. A 16 nm amorphous layer was created by ion implantation of Si+ at energy 5 keV and a dose 1×1015 at/cm2. As ion were implanted at 2 keV using 3 different doses: 1×1014, 5×1014 and 1×1015 at/cm2. The resulting As distributions, confined in the amorphous layer, were thermally treated at 550°C for 5-300 s in order to electrically activate dopant atoms. Crystal re-growth and As redistribution was investigated by secondary ion mass spectrometry and medium energy ion scattering. A growth rate depending on the As concentration was observed, the rate being slower for higher As content. Arsenic re-distribution to the surface and at the end-of-range defects was observed and a segregation model was developed. Finally, the substitutional fraction of As atoms was related to sheet resistance measurements revealing a higher fraction of electrically active dopant atoms in pre-amorphized samples compa...

Doping of Ge with Sn atoms by ion implantation and annealing by solid phase epitaxial re-growth process was investigated as a possible way to create GeSn layers. Ion implantation was carried out at liquid nitrogen to avoid nano-void formation and three implant doses were tested: 5×10, 1×10 and 5×10 at/cm, respectively. Implant energy was set to 45 keV and implants were carried out through an 11 nm SiNO film to prevent Sn out-diffusion upon annealing. This was only partially effective. Samples were then annealed in inert atmosphere either at 350°C varying anneal time or for 100 s varying temperature from 300 to 500°C. SPER was effective to anneal damage without Sn diffusion at 350° for samples implanted at medium and low fluences whereas the 5×10 at/cm samples remained with a ∼15 nm amorphous layer even when applying the highest thermal budget. © 2012 American Institute of Physics.

Spontaneous growth of arsenolite micro-crystals at room temperature after high fluence, low energy arsenic trihydride implantation in silicon was observed on the wafer surface after exposure to air. The crystals have been identified unambiguously by x-ray absorption and fluorescence spectroscopy. Thermal treatment easily sublimates the crystals at temperatures as low as 200 °C without any relevant in-diffusion of As into the substrate. The deposition of a thin As-rich layer under high fluence implantation conditions is suggested as possible precursor for crystal formation. The same layer can explain the anomalous retained dose increase often observed after annealing.

GrailQuest (Gamma-ray Astronomy International Laboratory for Quantum Exploration of Space-Time) is an ambitious astrophysical mission concept that uses a fleet of small satellites whose main objective is to search for a dispersion law for light propagation in vacuo. Within Quantum Gravity theories, different models for space-time quantization predict relative discrepancies of the speed of photons w.r.t. the speed of light that depend on the ratio of the photon energy to the Planck energy. This ratio is as small as 10-23 for photons in the γ- ray band (100 keV). Therefore, to detect this effect, light must propagate over enormous distances and the experiment must have extraordinary sensitivity. Gamma-Ray Bursts, occurring at cosmological distances, could be used to detect this tiny signature of space-time granularity. This can be obtained by coherently combine a huge number of small instruments distributed in space to act as a single detector of unprecedented effective area. This is the first example of high-energy distributed astronomy: a new concept of modular observatory of huge overall collecting area consisting in a fleet of small satellites in low orbits, with sub-microsecond time resolution and wide energy band (keV-MeV). The enormous number of collected photons will allow to effectively search these energy dependent delays. Moreover, GrailQuest will allow to perform temporal triangulation of impulsive events with arc-second positional accuracies: an extraordinary sensitive X-ray/Gamma all-sky monitor crucial for hunting the elusive electromagnetic counterparts of Gravitational Waves, that will play a paramount role in the future of Multi-messenger Astronomy. A pathfinder of GrailQuest is already under development through the HERMES (High Energy Rapid Modular Ensemble of Satellites) project: a fleet of six 3U cube-sats to be launched by the end of 2022.