Michele DoroUniversitat Autonoma de Barcelona (UAB)
Grup de Fisica de les Radiacions
Campus UAB - Edifici C-3, E-08193 Barcelona (Spain)
Since the Diploma Thesis I dealt with Astroparticle Physics, by joining the MAGIC collaboration (MAGIC stands for Major Atmospheric Gamma-ray Imaging telescope) with technological development and scientific tasks as main research occupation. MAGIC, operating since 2003 in the Canarian island La Palma, is currently the world largest Imaging Atmospheric Cherenkov Telescope (IACT). IACTs take advantage of the electromagnetic shower of particles initiated by very high energies cosmic gamma rays impinging onto the Earth atmosphere. The collection of Cherenkov photons produced by the electromagnetic shower permits the reconstruction of the primary gamma-ray energy and direction. Gamma-ray emission is related to non-thermal emission from galactic and extragalactic violent environments, such as pulsar wind nebulae, jets of particles from active galactic nuclei, the magnetosphere of pulsars and the gamma ray bursts, but many theories beyond the standard model of particles also predicts that dark matter can be seen in gamma-rays through its annihilation/decay products. MAGIC is constituted by two telescopes with parabolas of 17 m diameter that allow the attain of the lowest energy threshold of all IACTs, thus covering the open energy gap with gamma-ray satellite experiments. MAGIC is performing fundamental discoveries in astrophysics, like the discovery of gamma ray emission from a black hole at 5 billion light-years, revealing a more transparent universe than expected ("Very-High-Energy gamma rays from a Distant Quasar: How Transparent Is the Universe?", Science 320, 2008), and the pulsed emission of gamma-rays from the Crab pulsar ("Observation of Pulsed gamma-Rays Above 25 GeV from the Crab Pulsar with MAGIC", Science 322, 2008), or the first observation of very-high-energy gamma-ray emission from a microquasar ("Variable Very-High-Energy Gamma-Ray Emission from the Microquasar LS I +61 303", Science 312, 2006), unveiling important results on the acceleration of cosmic rays in this extreme objects.
Curriculum Vitae (English )
Diploma Thesis: Commissioning and Characterization of the Calibration
system of the MAGIC Telescope
PhD Thesis: Novel Reflective Elements and Indirect Dark Matter Searches for MAGIC and future IACTs. (pdf)
2004. Calibration System of the MAGIC I
As a diploma student, I performed by thesis in Barcelona, Spain at the Institut de Fisica d'Altes Energies (IFAE) institute. There I followed the characterization of the calibration system of the MAGIC telescope in its commissioning phase, flanked to M. Gaug (firstname.lastname@example.org). Ultra-fast avalanche transistors are used to switch LEDs at different wavelengths to simulate the fast (2 ns) pulses of Cherenkov light from atmospheric showers. The calibration system is also composed by a PIN-diode measurement and a "blind"-PMT. The characterization of the response of the calibration system and the analysis of the first calibration runs were performed. The main results of the study were a) that the calibration system recently installed on the telescope was fully operational and could be thereafter used, b) that the best calibration could be obtained with a combination of LEDs that better resembles the spectrum of Cherenkov light after atmospheric absorption. The diploma thesis was performed under the supervision of Manel Martinez (email@example.com). Part of the work was done at the MAGIC site. See my Diploma Thesis: "Commissioning and Characterization of the Calibration system of the MAGIC Telescope"
2006-09 Responsible of the reflective surface
of the MAGIC II telescope.
IACTs demand robust mirrors. Their large reflectors are usually tessellated with numerous mirror facets. As a PhD student, I was appointed by the MAGIC Padova group for heading the design, production, test-phase, optical characterization and installation of mirrors on the second MAGIC telescope (MAGIC-II), currently on its commissioning phase. MAGIC II mirrors are 1 sqm square-shaped, all-aluminum sandwich. They are composed of two aluminium plates interspaced by a honeycomb layer which provides rigidity, good heat transmission and light-weight (see, e.g., M. Doro et al. "The reflective surface of the MAGIC telescope", Nuclear Instruments and Methods in Physics Research Section A, Volume 595, Issue 1, p. 200-203.; M. Doro, Phd Thesis, Padova, 2009.). The design was optimized for larger surface and better insulation compared to MAGIC I mirrors. A search on the market was performed for an industrial partner for production and found in Vicenza, Italy (Compositex Srl). The surface of the aluminum sandwich is diamond-milled at the company LT-Ultra Precision, Germany. Then the surface is quartz-coated at IFAM, Bremen, Germany. Tooling and moulds were designed and produced. I followed also the optical qualification of each mirror during and at the end of the production (measurement of radius of curvature, spot-quality, reflectivity, insulation). The optical quality of these facets is very high: mean reflectivity larger than 85% in the Cherenkov wavelengths (mainly 300-600 nm), weight reduced to 18 kg/m2, very reduced reflectivity loss (1%/year) and good mechanical stability. I followed the optics qualification of the MAGIC II reflector thorough ray-tracing simulations and headed the installation of MAGIC II mirrors on the telescope in October 2007 and completed in August 2008, coordinating the installation. Currently I am studying the possibility of an absolute reflectivity measurement of mirrors mounted on MAGIC II with the use of an SBIG camera mounted at the center of the reflector and a reference star (following R. Mirzoyan et al. "A method to measure the mirror reflectivity of a prime focus telescope." Astropart.Phys.27:509-511,2007, e-Print: astro-ph/0703174)
2006-08 Dark Matter searches with MAGIC.
I was the principal investigator for three campaigns of observation of candidate sources of dark matter (DM) with the MAGIC telesope. The principal investigator (PI) is responsible for defining the scientific case, following observation and data analysis and curing the edition and publication of the data. In 2006, I proposed the observation of steady unidentified EGRET sources in the context of the intermediate mass black hole (IMBHs) scenario proposed by Bertone et al. (Phys.Rev.D72:103517,2005). IMBHs could be (they are not detected yet) very spiky DM enhancements possibly localized in the Milky Way halo. From numerical simulations, they show very high gamma-ray fluxes. They could be already in the EGRET catalog, but unidentified. A source was observed in 2006. Unfortunately, the telescope was undergoing major technical problems that prevented us from publication of these data. Only upper limits were derived. A description of the analysis can be found in the Diploma Thesis of a F. Zandanel which I followed as co-advisor: "Dark Matter Search with the MAGIC Telescope: Analysis of the Unidentified EGRET Source 3EG J1835+5918". In 2008 I was the PI of the observation of Willman 1 with MAGIC. Willman 1 is one of the recently discovered ultra-faint satellite galaxies with higher DM concentration (Strigari et al. arXiv:0709.1510 [astro-ph]). It was observed in 2008 for 15 hours with MAGIC. Upper limits were derived for few benchmarks neutralino models showing that prospects of detection are positive only under the assumption of relevant boosts in the models. The results were published: "Upper Limits on the VHE Gamma-Ray Emission from the Willman 1 Satellite Galaxy with the Magic Telescope", The Astrophysical Journal, Volume 697, Issue 2, pp. 1299-1304 (2009). I am also PI of a new target of observation, which was observed in 2009 and is currently under analysis.
2008 Co-coordinator of CTA mirror working
CTA (Cherenkov Telescope Array) is a developing project for a new generation of Cherenkov telescopes, extending the capabilities of the IACT technique as a result of the effort of the European or maybe world-wide gamma-ray community (see M. Doro for the CTA consortium, "CTA - A Project for a New Generation of Cherenkov Telescopes", Submitted to NIMA. eprint arXiv:0908.1410, E. Lorenz, M.Doro "Building Blocks for CTA: existing solutions and new designs. Mount and Mirrors"; A. Foerster, M. Doro, "Technical Information for the Development of Mirror Prototypes for the CTA Observatory", 2008). The CTA mirror working group is responsible for a) definition of technologies for mirror facets, b) definition of technology for mirror surface protection, c) creation of facilities for mirror massive test and performance characterization. I am personally developing aluminum mirrors for CTA, with improved design and performance. In addition, I follow the realization of a complete facility at National Laboratories in Legnaro (Padova, http://lnl.pd.infn.it) where the mirror prototypes should be fully tested. For exaple, we want to test focal length dependence with temperature, absolute reflectivity, exposure to salt-acid fog and intense UV illumination. We are therefore currently building a selfmade container where to install the mirror. We have contact with industrial partners and company for the realization of this project. The Padova group is the coordinator of this working package and I am coordinating of the activities within this group.
2008-09 Prospects of dark matter searches with
MAGIC II and CTA.
Besides current experiments, it is quite important in our field to study the prospect of observation of DM sources with future experiments, also due to the rapidly changing field of DM. The prospects of observation of two representative satellites were studied in the context of MAGIC II and CTA. The following aspects were clarified: a) which technical telescope aspects may influence the detection of DM, b) how much the increase in sensitivity and decrease of energy threshold affects the prospects of detection, c) that the recently-discovered internal bremmstrahlung mechanism (Bringmann et al, JHEP 0801:049,2008) introduces features in the gamma??ray spectrum that affect the detection probabilities for different models of neutralino; d) which are most probable regions of the parameter space of the neutralino for observation or constraints. The study can be found in T.Bringmann, M.Doro, M.Fornasa Dark matter signals from Draco and Willman 1: prospects for MAGIC II and CTA, JCAP 2009:01 (016). Currently I am working on a different topics with M. Fornasa (INFN-Padova) about how to deal with spectra features in the gamma-ray spectrum of annihilation of DM with IACTs.
Publications on refereed journals
Publications with the MAGIC collaboration (53,
up to 2009, Nov 1st)
For a full list of publications with the MAGIC collaboration, please refer to the Curriculum Vitae (English )
Talks at conferences
Partecipation in Books
Author: Michele Doro, (firstname.lastname@example.org). Last modified: 2009, Nov. 1st