Boosting the performance of the ASTRI SST-2M prototype: reflective and anti-reflective coatings

ASTRI is a Flagship Project of the Italian Ministry of Education, University and Research, led by the Italian National Institute of Astrophysics, INAF. One of the main aims of the ASTRI Project is the design, construction and verification on-field of a dual mirror (2M) end-to-end prototype for the Small Size Telescope (SST) envisaged to become part of the Cherenkov Telescope Array. The ASTRI SST-2M prototype adopts the Schwarzschild-Couder design, and a camera based on SiPM (Silicon Photo Multiplier); it will be assembled at the INAF astronomical site of Serra La Nave on mount Etna (Catania, Italy) within mid 2014, and will start scientific validation phase soon after. The peculiarities of the optical design and of the SiPM bandpass pushed towards specifically optimized choices in terms of reflective coatings for both the primary and the secondary mirror. In particular, multi-layer dielectric coatings, capable of filtering out the large Night Sky Background contamination at wavelengths $\lambda \gtrsim 700$ nm have been developed and tested, as a solution for the primary mirrors. Due to the conformation of the ASTRI SST-2M camera, a reimaging system based on thin pyramidal light guides could be optionally integrated aiming to increase the fill factor. An anti-reflective coating optimized for a wide range of incident angles faraway from normality was specifically developed to enhance the UV-optical transparency of these elements. The issues, strategy, simulations and experimental results are thoroughly presented.Comment: 4 pages, 6 figures. In Proceedings of the 33rd International Cosmic Ray Conference (ICRC2013), Rio de Janeiro (Brazil). All ASTRI contributions at arXiv:1307.463

Analysis of the thermal behaviour of the LFI-RAA cryogenic chamber in ALS

The scope of this document is to present a thermal analysis of the RAA Cryofacility used in the LFI QM Test in ALS . The data used for this analysis cover 8 days of testing: from the 18th to the 25th of July 2005. The aim of the analysis is to understand the behaviour of the LFI RAA cryogenic chamber and to provide useful indications to fully exploit the cryochamber thermal data during the instrument calibration data analysi

Mapping wastes in complex projects for Lean Product Development

Lean Product Development (LPD) is suggested as an approach that can reduce waste in projects aimed at developing technically complex items, which typically present substantial uncertainty about their output, as well as higher costs and longer development times. However, how can LPD be implemented in complex projects, where some redundancies in the development process are considered necessary in order to guarantee the quality of the final outcome? This paper answers this question, through a survey conducted at INAF, the Italian Institute of Astrophysics, that runs complex projects. The evidence shows that complex projects can actually be affected by the types of waste reported in LPD literature. Still, researchers may fail to determine the real priorities of intervention as they have trouble distinguishing between value-adding and value-destroying activities. Furthermore, they do not perceive the relevance of addressing the wastes generated by their own work; on the contrary, they place considerable attention on inefficiencies that are beyond the scope of their direct responsibilities. Recommendations to overcome this problem are proposed

In-flight calibration and verification of the Planck-LFI instrument

In this paper we discuss the Planck-LFI in-flight calibration campaign. After a brief overview of the ground test campaigns, we describe in detail the calibration and performance verification (CPV) phase, carried out in space during and just after the cool-down of LFI. We discuss in detail the functionality verification, the tuning of the front-end and warm electronics, the preliminary performance assessment and the thermal susceptibility tests. The logic, sequence, goals and results of the in-flight tests are discussed. All the calibration activities were successfully carried out and the instrument response was comparable to the one observed on ground. For some channels the in-flight tuning activity allowed us to improve significantly the noise performance.Comment: Long technical paper on Planck LFI in flight calibration campaign: 109 pages in this (not final) version, 100 page in the final JINST versio

The Large-Scale Polarization Explorer (LSPE)

The LSPE is a balloon-borne mission aimed at measuring the polarization of the Cosmic Microwave Background (CMB) at large angular scales, and in particular to constrain the curl component of CMB polarization (B-modes) produced by tensor perturbations generated during cosmic inflation, in the very early universe. Its primary target is to improve the limit on the ratio of tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7% confidence. A second target is to produce wide maps of foreground polarization generated in our Galaxy by synchrotron emission and interstellar dust emission. These will be important to map Galactic magnetic fields and to study the properties of ionized gas and of diffuse interstellar dust in our Galaxy. The mission is optimized for large angular scales, with coarse angular resolution (around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload will fly in a circumpolar long duration balloon mission during the polar night. Using the Earth as a giant solar shield, the instrument will spin in azimuth, observing a large fraction of the northern sky. The payload will host two instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters, using large throughput multi-mode bolometers and rotating Half Wave Plates (HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz. The wide frequency coverage will allow optimal control of the polarized foregrounds, with comparable angular resolution at all frequencies.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibite

Square Kilometer Array project status report

This paper will describe the progress of the SKA-1 Telescope during the period from Preliminary Design Review to Critical Design Review. In addition to this, it will provide information on the management of the project with respect to managing cost and scope whilst working within a fixed cost cap. The paper will consider the balance between the technical choices made with the risk of delivering a large, distributed observatory across several continents. In addition, it will consider the challenges of carrying this out whilst developing the organisation towards an Inter-Governmental Organisation. It will consider, briefly, the key management tools used and the lessons learned...