B. Negri

The LAUE project and its main results

We will describe the LAUE project, supported by the Italian Space Agency, whose aim is to demonstrate the capability to build a focusing optics in the hard X-/soft gamma-ray domain (80{600 keV). To show the lens feasibility, the assembling of a Laue lens petal prototype with 20 m focal length is ongoing. Indeed, a feasibility study, within the LAUE project, has demonstrated that a Laue lens made of petals is feasible. Our goal is a lens in the 80-600 keV energy band. In addition to a detailed description of the new LARIX facility, in which the lens is being assembled, we will report the results of the project obtained so far.

NHXM: a New Hard X-ray imaging and polarimetric Mission

The New Hard X-ray Mission (NHXM) has been designed to provide a real breakthrough on a number of hot astrophysical issues that includes: black holes census, the physics of accretion, the particle acceleration mechanisms, the effects of radiative transfer in highly magnetized plasmas and strong gravitational fields. NHXM combines fine imaging capability up to 80 keV, today available only at E<10 keV, with sensitive photoelectric imaging polarimetry. It consists of four identical mirrors, with a 10 m focal length, achieved after launch by means of a deployable structure. Three of the four telescopes will have at their focus identical spectral-imaging cameras, while a X-ray imaging polarimeter will be placed at the focus of the fourth. In order to ensure a low and stable background, NHXM will be placed in a low Earth equatorial orbit. Here we will provide an overall description of this mission and of the developments that are currently occurring in Italy. In the meanwhile we are forming an international collaboration, with the goal to have a consortium of leading Institutes and people that are at the forefront of the scientific and technological developments that are relevant for this mission.

The LAUE project for broadband gamma-ray focusing lenses

We present the LAUE project devoted to develop an advanced technology for building a high focal length Laue lens for soft gamma-ray astronomy (80-600 keV). The final goal is to develop a focusing optics that can improve the current sensitivity in the above energy band by 2 orders of magnitude.

Design and development of the optics system for the NHXM Hard X-ray and Polarimetric Mission

The New Hard X-ray Mission (NHXM) Italian project will be operated by 2016. It is based on 4 hard X-ray optics modules, each formed by 60 evenly spaced multilayer coated Wolter I mirror shells. For the achievement of a long focal length (10 m) an extensible bench is used. The pseudo-cylindrical Wolter I monolithic substrates where the multilayer coating is applied will be produced using the Ni electroforming replica approach. For three of the four mirror modules the focal plane will host a hybrid a detector system, consisting in the combination of a Si-based low energy detector (efficient from 0.5 up to ~ 15 keV) , on top of a high energy CdTe pixellated detector (efficient from 10 keV up to ~ 80 keV); the two cameras will be surrounded by both a passive shield and an anticoincidence shield. The total on axis effective area of the three telescopes at 1 keV and at 30 kev is of 1500 cm2 and 350 cm2 respectively. The angular resolution requirement is better than 20 arcsec HEW at 30 keV, while the Field of View at 50% vignetting is 12 arcmin (diameter). The payload is finally completed with the fourth telescope module, that will have as a focal plane detector a high sensitivity imaging photoelectric polarimetric system, operating from 2 up to 35 keV. In this paper, after an overview of the mission configuration and its scientific goals, we report on the design and development of the multilayer optics of the mission, based on thin replicated Ni mirror shells.

Development of grazing-incidence multilayer mirrors by direct Ni electroforming replication: a status report

The Ni electroforming replication process has been used successfully by Beppo-SAX, JET-X/SWIFT, and XMM-Newton, to produce their gold-coated X-ray mirrors. The important feature of the technique is that, also with thin substrates, it is possible to achieve a good angular resolution, which is important for obtaining high signal-to-noise ratios in deep observations and imaging extended sources, while the assembly and integration of the monolithic shells is a relatively easy task. Two approaches can be used for the up grade of this technique also to the case of mirrors with multilayer coating, to be used in future hard X-ray missions: i) the direct replication of the mirror shell, after the deposition of the multilayer film on the master (mandrel) surface followed by the electroforming of the Ni walls, ii) the application of the multilayer film to the internal surface of Ni mirror shells, previously realized by replication. In this paper the last results achieved in Italy in the context of an activity aiming at the development of the former of the two methods will be presented and discussed.

Development status of the LAUE project

We present the status of LAUE, a project supported by the Italian Space Agency (ASI), and devoted to develop Laue lenses with long focal length (from 10–15 meters up to 100 meters), for hard X–/soft gamma–ray astronomy (80-600 keV). Thanks to their focusing capability, the design goal is to improve the sensitivity of the current instrumention in the above energy band by 2 orders of magnitude, down to a few times 10−8 photons/(cm2 s keV).

Scientific prospects in soft gamma-ray astronomy enabled by the LAUE project

This paper summarizes the development of a successful project, LAUE, supported by the Italian Space Agency (ASI) and devoted to the development of long foca length (up to 100—m) Laue lenses for hard X–/soft gamma– ray astronomy (80-600 keV). The apparatus is ready and the assembling of a prototype lens petal is ongoing. The great achievement of this project is the use of bent crystals. From measurements obtained on single crystals and from simulations, we have estimated the expected Point Spread Function and thus the sensitivity of a lens made of petals. The expected sensitivity is a few ×10−8 photons cm−2 s−1 keV−1). We discuss a number of open astrophysical questions that can settled with such an instrument aboard a free-flying satellite.

CZT X-ray detectors obtained by the boron encapsulated vertical Bridgman method

Recently, some of the authors showed that it is possible to grow CZT crystals by the boron oxide encapsulated vertical Bridgman method. The most important feature of the technique is that the crystal, during the growth, is fully encapsulated by a thin layer of liquid boron oxide, so that the crystal-crucible contact is prevented. The stress of the crucible to the crystal is strongly reduced also during the cooling, because the boron oxide layer is molten down to about 500°C. A number of detectors have been prepared out of these crystals. The transport properties (μτ product) have been studied by photoconductivity measurements as well as by determining the response to hard X-ray irradiation. The transport properties have been studied as a function of the indium content and of the position of the wafer which the detector was cut out.

Development status of a Laue lens project for gamma-ray astronomy

We report the status of the HAXTEL project, devoted to perform a design study and the development of a Laue lens prototype. After a summary of the major results of the design study, the approach adopted to develop a Demonstration Model of a Laue lens is discussed, the set up described, and some results presented.

Characterisation of a CZT focal plane small prototype for hard X-ray telescope

We are working on the development of a balloon borne telescope based on multilayer optics for energy from /spl sim/10 keV up 80 keV. This hard X-ray telescope requires a high efficiency focal plane providing both fine spatial resolution and spectroscopy with a compact and robust design. Currently the most appealing choice is offered by the development of CdTe/CZT detectors. Herein we present the characterization both in spectroscopic and spatial response of a small CZT detector (1 cm/sup 2/) with 0.5 mm pixel size. The readout of the detector use an innovative low noise and low power dissipation ASICs developed within the collaboration. We present the results of tests with both collimated and non collimated radioactive sources using the RENA front-end electronics and a back-end electronics, that comprises a 64 independent channels system with coincidence logic.