RESEARCH – INSTRUMENTATION

Ge bolometer for IR astronomy

During my thesis (1979-1983) at the Institute of Physics of Interplanetary Space CNR/IFSI, I contributed to the design, realization and calibration of a liquid helium-cooled Ge bolometer operating at 1.6 K in the range 1-27 μm. The bolometer was equipped with a set of broad-band filters and a Circular Variable Filter (CVF) operating in the range 1-14 μm. In particular N1, N2 and N3 were chosen in order to overlap the  9.7 micron Silicate dust band and the adjacent wings.

MOF Telescopes

My activity in experimental solar physics began in the 90s during the preparation of a proposal for an imager based on telescope using a couple of Magneto-Optical filters (MOFs) for the mission NASA/ESA SOHO (collaboration with La Sapienza and NASA-JPL). The prototype instrument, that used MOF at 770.1 nm (K D1 line), has been used for several years on the roof of the Department of Physics (University of Rome Sapienza) by the Team of Prof. A. Cacciani. More recently, I collaborated at the Magneto Optical Filters at Two Heights (MOTH) experiment (PI. Prof. S. Jefferies) consisting of two Doppler-magnetographs that each measure the line-of-sight Doppler velocity and magnetic fields over the full solar disk at a given (different) height in the Sun’s atmosphere. MOTH uses MOFs at 589 nm (Na D2-line) and 770 nm (K D1-line) and looks at the photosphere low chromosphere region of the Sun’s atmosphere (between 400 km and 700 km). A polar version of MOTH was used during the South Pole campaigns 2016-2017 and 2017-2018.

Antarctica: Tor Vergata researchers at work to install the MOTH II solar telescope

 

IPM at the Solar telescope THEMIS

After, I participated to the collaboration between Italian research institutes (i.e., University of Florence, University of Rome Tor Vergata and Arcetri Observatory), the Meudon Observatory and CNRS institutes for the focal plane instruments at the French-Italian telescope THEMIS (Tenerife, Canary Islands, Spain).  I was involved in the development of the imager and aquistion s/w  and calibration pipeline for the Italian Panoramic Monochromator (IPM).  It basically consisted of a Fabry-Perot interferometer (FPI) mounted in tandem with an Universal Birefringent Filter (UBF) with a final 20 mÅ FWHM pass band.  The image acquisition system consisted of two CCD cameras controlled and read-out by dedicated electronics, realized at UNITOV, and personal computers. One of these cameras acquired a simultaneous broad band (called white light) image for the application of off-line destretching procedures in order to reduce seeing effects. A custom optical link, realized at UNITOV, connected the CCD camera and the PCs while the handshaking and the data transfer between the PCs and the work station controlling the IPM was performed via LAN and IEE488 bus. IPM was installed at THEMIS in September 1996 (operative until 2006).

IBIS at Sacramento Peak / National Solar Observatory

At the end of 90s  I participated in the working group (PI Dr. Fabio Cavallini – Arcetri Astrophysical Observatory) for the realization of the double Fabry-Perot IBIS panoramic interferometer. IBIS is an instrument for imaging spectroscopy installed in the summer 2002 at the Dunn Solar Telescope at NSO/Sacramento Peak. The instrument has been constructed by a consortium of italian institutes and allows for observations of the photosphere and chromosphere at high spatial, spectral, and temporal resolution. Such observations are essential for performing spatial and spectral comparisons with numerical simulations. We will present some of the performance characteristics of the instrument and show some examples of the IBIS data. We will also show some initial results of the recently tested polarimetric mode. IBIS is available for community use as a facility instrument of NSO.IBIS has been funded by the Italian Research Ministry (MIUR), the Italian Institute for Astrophysics (INAF), and the Universities of Florence and Rome Tor Vergata. Additional support was provided by the National Solar Observatory.

Heat stop for the 4-m European Solar Telescope EST

During the preliminary study for the 4-m European Solar Telescope EST (FP7-EST) I lead the team who presented various projects for the realization of the heat stop for EST. EST is an on-axis Gregorian telescope, equipped with a four-meter diameter primary mirror and primary focal length of about six meters. The heat stop, positioned at the primary focus, must be able to remove a heat load of 13 kW, while maintaining its surfaces very close to room temperature,
to avoid the onset of seeing. In order to remove the heat, three configurations have been taken into consideration: 1) a flat 45◦ inclined heat rejecter, 2) a 45◦ conical heat rejecter and 3) a heat trap (made of a conical heat rejecter and a cylindrical heat absorber). All devices include an air removal system to avoid the formation of thermal plumes. The adopted cooling method is the Jet impingement, which is proper to applications involving high heat fluxes absorption. This method utilizes a small nozzle (about 1mm of diameter) to increase the velocity of a cooling fluid (in the present case, a water-based coolant has been considered). The coolant turbulent flows impact the target surface increasing its heat transfer coefficient (HTC). The project is in collaboration with SRS Engineering.

Large Etalon for the 4-m European Solar Telescope EST

I organized the team that deals with the design, realization and calibration of the large etalon for EST. The team was composed by A.D.S. International and CNR-National Institute of Optics (INO). During the design study A.D.S. performed a FEA thermo-mechanical optimization of mechanical mount for FPIs from Ø100mm to Ø300mm for vertical and horizontal operation. Moreover, S.R.S. realized a detailed design of a 150mm FPI prototype in collaboration with IC Optical Systems. The optical tests have been realized at INO.

ADAHELI Design of the First Italian Solar Mission

I was PI of the ADAHELI (ADvanced Astronomy for HELIophysics) is a small-class (500 kg) low-budget  satellite mission for the study of the solar photosphere and the chromosphere and for monitoring solar flare emission. ADAHELI‘s design has completed its Phase-A feasibility study in December 2008, in the framework of ASI’s (Agenzia Spaziale Italiana) 2007 “Small Missions” Program (calling for two missions at 50 MEeuros each, plus the launch budget). ADAHELI‘s main purpose is to explore Sun’s lower atmosphere in the near-infrared, a region so far unexplored by solar observations from space. ADAHELI will carry out observations of the solar photosphere and of the chromosphere at high-temporal rate and high spatial and spectral resolutions. ADAHELI will contribute to the understanding of Space Weather through the study of particle acceleration during flares. A radiometer operating in the millimeter radio band will continuously monitor the solar disk, throughout the spacecraft’s life time. ADAHELI‘s baseline instruments are a 50-cm high-resolution telescope operating in the visible and the near-infrared, and a lightweight full-disk radiometer operating at millimeter wavelengths (90 GHz). The core of the telescope’s focal plane suite is the spectral imager based on two Fabry-Perot interferometers, flying for the first time on a solar mission. The instrument will return fast-cadence, full bi-dimensional spectral images at high-resolution, thus improving on current slit-scan, mono-dimensional architectures. Moreover, the possibility of working in polarized light will enable full 3D magnetic field reconstruction on the photosphere and the chromosphere. An optional instrumental package is also being proposed to further extend ADAHELI‘s scope: a full-disk telescope for helioseismology based on a double Magneto-Optical Filter, a Neutral Particle Analyzer for magnetospheric research, an Extreme Ultraviolet imaging and spectro-radiometry instrument. These options fall outside the prescribed budget. ADAHELI, flying a Sun-Synchronous orbit at 800 km, will perform continuous, long-duration (4-h), daily acquisitions, with the possibility of extending them up to 24 h. ADAHELI‘s operating life is two years, plus one extension year. Launch would be nominally planned for 2014.

ADAHELI Plus: a proposed ESA Solar Mission Design for VIS-NIR spectropolarimetry and X-ray Polarimetry 

I was PI of the Advanced Astronomy for Heliophysics Plus (ADAHELI Plus) is a project concept for a small solar and space weather mission with a budget compatible with an European Space Agency (ESA) S-class mission, including launch, and a fast development cycle. ADAHELI was submitted to the European Space Agency by a European-wide consortium of solar physics research institutes in response to the “Call for a small mission opportunity for a launch in 2017,” of March 9, 2012. The ADAHELI project builds on the heritage of the former ADAHELI mission, which had successfully completed its phase-A study under the Italian Space Agency 2007 Small Mission Programme, thus proving the soundness and feasibility of its innovative low-budget design. ADAHELI is a solar space mission with two main instruments: ISODY: an imager, based on Fabry-Pérot interferometers, whose design is optimized to the acquisition of highest cadence, long-duration, multiline spectropolarimetric images in the visible/near-infrared region of the solar spectrum. XSPO: an x-ray polarimeter for solar flares in x-rays with energies in the 15 to 35 keV range. ADAHELI is capable of performing observations that cannot be addressed by other currently planned solar space missions, due to their limited telemetry, or by ground-based facilities, due to the problematic effect of the terrestrial atmosphere.