The LAUE project: a broad band gamma-ray focusing lens

Transcription

1 The LAUE project: a broad band gamma-ray focusing lens E. Virgilli a, F. Frontera a, V. Valsan a, V. Liccardo a, E. Caroli b, J.B. Stephen b, F. Cassese c, L. Recanatesi c, M. Pecora d, S. Mottini e, P. Attinà e and B. Negri f (a) Physics Department, University of Ferrara (b) IASF INAF, Bologna (c) DTM Technologies, Modena (d) Thales Alenia Space, Milan (e) Thales Alenia Space, Turin (f) ASI Agenzia Spaziale Italiana Second Ferrara Workshop on X ray Astrophysics up to 511 kev 2011 September, 14 16

2 What is a Laue lens? The Bragg Law 2d hkl sinθ B = n c E B Energy radius relation: c f E B d hkl R ring

3 What is a Laue lens? The Bragg Law 2d hkl sinθ B = n c E B Energy radius relation: c f E B d hkl R ring

4 The LAUE project The main objective: a focusing lens for hard X-/soft γ-rays kev Goals of the LAUE project Development of a technology for a massive production of crystals for diffraction, with high efficiency and desired spread (20 30 arcsec); Development of a technology to assemble a large number of crystals with a positioning accuracy better than 10 arcsec; Development of a facility for assembling the crystals on a petal with the required accuracy and for the performance tests; Realization of a petal using the selected crystals; Feasibility study for assembling an entire lens made of petals, for space application.

5 The LAUE project The main objective: a focusing lens for hard X-/soft γ-rays kev Goals of the LAUE project Development of a technology for a massive production of crystals for diffraction, with high efficiency and desired spread (20 30 arcsec); Development of a technology to assemble a large number of crystals with a positioning accuracy better than 10 arcsec; Development of a facility for assembling the crystals on a petal with the required accuracy and for the performance tests; Realization of a petal using the selected crystals; Feasibility study for assembling an entire lens made of petals, for space application.

6 Why a LAUE project? From the HAXTEL to the LAUE project In the HAXTEL project 3 phases were used for positioning each crystal: gluing pins as references for the diffractive planes; positioning in a drilled countermask; gluing the set of crystals on the carbon fiber support. Problems Time consuming; Limited accuracy due to the multi-phase process.

7 The LAUE project: a lens for X and γ-rays How to assemble hundreds of crystals? In the LAUE project the crystals will be directly placed on a carbon fiber support using a mechanical device (DTM Technologies)

8 The LAUE project: a lens for X and γ-rays How to assemble hundreds of crystals? In the LAUE project the crystals will be directly placed on a carbon fiber support using a mechanical device (DTM Technologies)

9 The LAUE project: a lens for X and γ-rays How to assemble hundreds of crystals? In the LAUE project the crystals will be directly placed on a carbon fiber support using a mechanical device (DTM Technologies) Advantages Faster alignment; Expected accuracy 10 times better than in the HAXTEL method ( 10 arcsec).

10 The LAUE project A focusing lens for hard X-/soft γ-rays kev Goals of the LAUE project Development of a technology for a massive production of crystals for diffraction, with high efficiency and desired spread (20 30 arcsec); Development of a technology to assemble a large number of crystals with a positioning accuracy better than 10 arcsec; Development of a facility for assembling the crystals on a petal with the required accuracy and for the performance tests; Realization of a petal using the selected crystals; Feasibility study for assembling an entire lens made of petals, for space application.

11 Assembling petals for space applications Payload modularity A modular approach to the system architecture has been adopted. The basic elements (crystals) are assembled into petals. The optical bench provides accommodation for the petals. Thales Alenia Space is performing feasibility studies for: Modularity; Structural stability; Thermal stability.

12 The LAUE project A focusing lens for hard X-/soft γ-rays kev Goals of the LAUE project Development of a technology for a massive production of crystals for diffraction, with high efficiency and desired spread (20 30 arcsec); Development of a technology to assemble a large number of crystals with a positioning accuracy better than 10 arcsec; Development of a facility for assembling many crystals on a petal with the required accuracy and for the performance tests; Realization of a petal using the selected crystals; Feasibility study for assembling an entire lens made of petals, for space application.

13 The LAUE project: a lens for X and γ-rays Building a petal Petal properties On the basis of: available X-ray source (up to 320 kev); pipeline dimensions.

14 The LAUE project Building a petal Petal properties On the basis of: available X-ray source (< 320 kev); pipe-line dimension. Petal properties Passband kev Focal Length 20 m Crystal size 3 1 cm 2 optimized N o crystals thickness (depending on the subtendle petal angle 18 o ) N o rings 18

15 The LAUE project A focusing lens for hard X-/soft γ-rays kev Goals of the LAUE project Development of a technology for a massive production of crystals for diffraction, with high efficiency and desired spread (20 30 arcsec); Development of a technology to assemble a large number of crystals with a positioning accuracy better than 10 arcsec; Development of a facility for assembling the crystals on a petal with the required accuracy and for the performance tests; Realization of a petal using the selected crystals; Feasibility study for assembling an entire lens made of petals, for space application.

16 The LARIX facility

17 The LARIX facility Photon source X-ray tube up to 320 kev Pipe-line Vacuum environment (1 10 mbar) Input Output windows Transparency: 80 kev Collimator Remote control, ±0.1 mm spatial accuracy Clean room Class 10 5, humidity stable 50%, temperature ±1 C Robotic device Mechanical holder for crystals alignment Assembled/tested petal Defined properties Detectors HPGe spectral resolution: 200 ev Imager spatial resolution: 300 µm

18 The LARIX facility Photon source X-ray tube up to 320 kev Pipe-line Vacuum environment (1 10 mbar) Input Output windows Transparency: 80 kev Collimator Remote control, ±0.1 mm spatial accuracy Clean room Class 10 5, humidity stable 50%, temperature ±1 C Robotic device Mechanical holder for crystals alignment Assembled/tested petal Defined properties Detectors HPGe spectral resolution: 200 ev Imager spatial resolution: 300 µm

19 X-ray source and collimator Source and Collimator are moved together along Y and Z axis providing a parallel X-ray beam to the target with a precision of ±0.1 mm (few 20 m)

20 Alignment Building procedure Alignment X-ray beam/collimator aperture; Adjustment of the slit aperture with respect to the crystal size; For n = 1 total number of crystals: Positioning of the crystal on the holding device; Translation of X-ray source and collimator to irradiate the crystal; Tilting/adjusting the crystal; Aquiring the position of the diffracted image; Comparison between the aquired image and a reference image; Spectral cross-check (energy E n); Gluing the crystal on the frame polymerization phase (t < 30 min); Pull back the holding device. Testing the petal.

21 Alignment Building procedure Alignment X-ray beam/collimator aperture; Adjustment of the slit aperture with respect to the crystal size; For n = 1 total number of crystals: Positioning of the crystal on the holding device; Translation of X-ray source and collimator to irradiate the crystal; Tilting/adjusting the crystal; Aquiring the position of the diffracted image; Comparison between the aquired image and a reference image; Spectral cross-check (energy E n); Gluing the crystal on the frame polymerization phase (t < 30 min); Pull back the holding device. Testing the petal.

22 Alignment Building procedure Alignment X-ray beam/collimator aperture; Adjustment of the slit aperture with respect to the crystal size; For n = 1 total number of crystals: Positioning of the crystal on the holding device; Translation of X-ray source and collimator to irradiate the crystal; Tilting/adjusting the crystal; Aquiring the position of the diffracted image; Comparison between the aquired image and a reference image; Spectral cross-check (energy E n); Gluing the crystal on the frame polymerization phase (t < 30 min); Pull back the holding device. Testing the petal.

23 Alignment Building procedure Alignment X-ray beam/collimator aperture; Adjustment of the slit aperture with respect to the crystal size; For n = 1 total number of crystals: Positioning of the crystal on the holding device; Translation of X-ray source and collimator to irradiate the crystal; Tilting/adjusting the crystal; Aquiring the position of the diffracted image; Comparison between the aquired image and a reference image; Spectral cross-check (energy E n); Gluing the crystal on the frame polymerization phase (t < 30 min); Pull back the holding device. Testing the petal.

24 Alignment Building procedure Alignment X-ray beam/collimator aperture; Adjustment of the slit aperture with respect to the crystal size; For n = 1 total number of crystals: Positioning of the crystal on the holding device; Translation of X-ray source and collimator to irradiate the crystal; Tilting/adjusting the crystal; Aquiring the position of the diffracted image; Comparison between the aquired image and a reference image; Spectral cross-check (energy E n); Gluing the crystal on the frame polymerization phase (t < 30 min); Pull back the holding device. Testing the petal.

25 Alignment Building procedure Alignment X-ray beam/collimator aperture; Adjustment of the slit aperture with respect to the crystal size; For n = 1 total number of crystals: Positioning of the crystal on the holding device; Translation of X-ray source and collimator to irradiate the crystal; Tilting/adjusting the crystal; Aquiring the position of the diffracted image; Comparison between the aquired image and a reference image; Spectral cross-check (energy E n); Gluing the crystal on the frame polymerization phase (t < 30 min); Pull back the holding device. Testing the petal.

26 The LAUE project A focusing lens for hard X-/soft γ-rays kev Goals of the LAUE project Development of a technology for a massive production of crystals for diffraction, with high efficiency and desired spread (20 30 arcsec); Development of a technology to assemble a large number of crystals with a positioning accuracy better than 10 arcsec; Development of a facility for assembling the crystals on a petal with the required accuracy and for the performance tests; Realization of a petal using the selected crystals; Feasibility study for assembling an entire lens made of petals, for space application.

27 Crystal selection Proper materials and dimensions with higher efficiency and suitable spread Mosaic 100 kev for the HAXTEL project provided by the Institute Laue Langevin - Genève (ILL) Bent 150 kev (Barriere, Guidi et al. 2009) Tentatively curved crystals. Efficency measurement to decide among: curved mosaic curved perfect

28 Crystal selection Selected materials GaAs [220] mosaic (bent) Si [111] perfect (bent) Ge [220] perfect (bent) Provided by: Sensors and Semiconductors Laboratory (LSS Ferrara) Istituto dei Materiali per l Elettronica ed il Magnetismo (IMEM Parma)

29 Bent crystals Through indentation method Indentations on the surface induce a stress causing the curvature of the entire lattice structure. Primary mode The indentations bend under a certain R p the planes directly suited for the diffraction. Secondary mode External and internal curvature (R i ) strictly related eachother. bent crystals PROS: high reflectivity CONS: no focusing effects quasi-mosaic crystals PROS: focusing capability CONS: lower reflectivity

30 PSF simulation of a ring of crystals: ideal alignment Quasi-mosaic crystals vs. mosaic crystals Crystal size: cm 2 Thickness: 0.8 cm Simulation with the same number of photons for each crystal in the ring (10 5 ph) Quasi-mosaic crystals peak value Mosaic crystals peak value

31 Enclosed photons: the ideal case with no-divergence effect Quasi-mosaic crystals vs. mosaic crystals Enclosed photons 5.82 mm for mosaic crystals 3.75 mm for quasi-mosaic crystals

32 Misalignment effects Crystal size: cm 2 With a gaussian distribution for the misalignments: 30 arcsec 1.3% 60 arcsec 0.8%

33 The crystal size dependence...and misalignment effects Crystal cross section cm mm Crystal cross section cm mm (!!) But 1 arcmin of misalignment almost makes useless a smaller tangential dimension of the crystals

34 Conclusions (I) Laue lenses represents a step forward to solve astrophysical key questions, both for continuum and narrow lines. Technology for low FL (3 10 meters) already tested and optimized Frontera et al. 2008, see also Valsan s Poster P 09 for new prototype results

35 Conclusions (II) Technology for > 15 m FL is in the final developing stage (LAUE project): Defined a technology for a fast and accurate alignment of the crystals; Assembled a facility for build/test a petal; Aquired the know-how to align the crystals and build a petal; Performed a feasibility study for assembling a Laue lens made of petals.

36 Conclusions (III) Crystal selection and properties: Developed technology for the production of a large number of crystals suitable for Laue lenses; Indented (bent) Silicon can be provided with the requested curvature; Bent crystals improve angular resolution by an order of magnitude with respect to flat crystals. If this promising PSF will be supported by good reflectivity measurements, bent crystals will be a breakthrough for LAUE lenses.