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X-Ray Polarimetry Programs in Italy

X-Ray Polarimetry Programs in Italy. Enrico Costa IASF-INAF Roma. POLARIX. A pathfinder Mission of X-Ray Polarimetry Roma 17/10/2008 Enrico Costa , IASF – Roma , INAF, et al. On behalf of the POLARIX Team. Program of ASI for Small Missions.

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X-Ray Polarimetry Programs in Italy

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  1. X-Ray Polarimetry Programs in Italy Enrico Costa IASF-INAF Roma

  2. POLARIX A pathfinder Mission of X-Ray Polarimetry Roma 17/10/2008 Enrico Costa, IASF– Roma, INAF, et al. On behalfof the POLARIX Team

  3. Program of ASI for Small Missions • Announcement of Opportunity with deadline October 2007 • On Feb 7 2008 ASI approved phase A studies for 5 Missions • Phase A studies started on April and will be completed by December 10. • Each Study was supported with 750 k€ grant • On the basis of outcome of phase A studies ASI will select two missions to be launched on 2012 and 2014. • The total cost of each mission should stay wthin 50 M€ + launch with a VEGA • 5 phase A studies approved: SAGACE, POLARIX, FLORAD, MAGIA, ADAHELI

  4. MISSIONS in A phase • SAGACE (Spectroscopic Active Galaxies And Clusters Explorer), PI: Prof. Paolo De Bernardis, Universita’ La Sapienza (Roma) • Specroscopy study of SZ effect. Large scale structures. Hubble Constant, DM, DE. MW catalogue of Star • FLORAD (Costellazione FLOreale micro-satellitare di RADiometri in banda millimetrica per l'Osservazione della Terra e dello Spazio a scala regionale) PI: Prof. Frank Marzano, Università La Sapienza (Roma) • To launch a constellation of micro-satellites, each equiped with a MW radiometer in mm band, for remote sensing oftemperature, vapours, cloud water, for nowcasting and forecasting on the Mediterranean area for environment and civil protection purposes. • MAGIA (Missione Altimetrica Gravimetrica geochimica lunAre) PI: Prof. A. Coradini INAF-IFSI • Geochemistry and mineralogy of the moon surface by remote sensing • ADAHELI (ADvanced Astronomy for HELIophysics) PI: Prof. Francesco Berrilli, Universita’ di Tor Vergata • Photospheric and Chromospheric Dynamics studied by NIR observations. Radiance in mm band with < arcmin resolution. • POLARIX (POLARimetro X) PI: Prof. Enrico COSTA, IASF • Prime Contractor: IASF - Roma

  5. POLARIX Team • Enrico Costaa, Ronaldo Bellazzini c, Gianpiero Tagliaferrid, Luca Baldinic, Stefano Bassod, Johan Bregeonc, Alessandro Brezc, Oberto Citteriod, Vincenzo Cotroneod, Sergio Di Cosimoa, Sergio Fabiania, Marco Ferocia, Massimo Fruttia, Francesco Lazzarottoa, Giorgio Matte, Massimo Minutic, E.Morellif, Fabio Muleria,b, Giovanni Pareschid, Michele Pincherac ,Alda Rubinia, Carmelo Sgroc, Paolo Soffittaa, Gloria Spandrec • Istituto di Astrofisica Spaziale e Fisica Cosmica, INAF, Roma, Italy; • Universita’ di Roma Tor Vergata, Dipartimento di Fisica, Roma, Italy; • Istituto Nazionale di Fisica Nucleare, Pisa, Italy; • Osservatorio Astronomico di Brera, INAF, Merate (Lc), Italy; • Universita’ di Roma Tre, Dipartimento di Fisica, Roma , Italy; • Istituto di Astrofisica Spaziale e Fisica Cosmica, INAF, Bologna (BO), Italy.

  6. MANAGEMENT • The POLARIX project will be realized, under ASI contract and general management, with a common Italian effort of following Institutes and national space firms: • INAF - ISTITUTO ASTROFISICA SPAZIALE E FISICA COSMICA-ROMA • INAF- OSSERVATORIO ASTRONOMICO DI BRERA • INFN – SEZIONE DI PISA • THALES ALENIA SPACE – TORINO • THALES ALENIA SPACE – MILANO • TELESPAZIO - ROMA • The flight instrument and the ground systems will be developed with the responsibilities of the Institutions as listed in the table below.

  7. The POLARIX Concept • To open the windowofX-ray polarimetry by: • Exploiting the capabilityofGas Pixel Detectors, a newallitaliantechnology, developedby Pisa INFN, toperform polarimetry, imaging, timing and spectroscopyofX-sources, withunprecedentedsensitivity, whenusedas a focalplanedevice. • Benefitingof the existingtelescopes(2 FU and 1 EM) developedby OAB for the JET-X program and alreadytested in flight with SWIFT. The exstenceofmandrelscouldallow (NtH) for the manufactureoftwo more telescopes. • Benefitingof the heritageofspaceelectronicsfromThalesAleniaspace-MI and of the more recentexperienceofonboardhandling data ofcomplexscientificmissions. • Benefitingof the long heritageofThalesAleniaspace-TO on the buildongofbusesforscientificmissions. Benefitingaswellofcommonalitieswithothermissions under development. • By a wiseuseofalreadyavailableitemswewanttomake a break-throughmission in the tight finaciallimitsdefinedby the announcement (50M€).

  8. SPACE SEGMENT LIFETIME SPACE SEGMENT LIFETIME REQUIREMENTS 14 months of full operation are sufficient to open the new window of X-ray polarimetry with a coverage of the major issues in the present literature. Beside a full cycle of 12 months (+ 1 SVP month) it allows for a minimal feed-back on the POLARIX results themselves. A lifetime of 4 years would allow for a adaptive program based on results of POLARIX, expected theoretical analysis and new data from other missions/observatories. Overlap with SIMBOL-X would be extremely effective. OPERATIONAL ORBIT

  9. Available Telescopes • Three modules are available (@ OAB - Merate) from Jet-X mission. • Advantages: low costs • Disadvantage: high mass HEWmeas = 15 arcsec

  10. X-ray imaging test of a thin JET-X mirror shell (July ‘02) • diam. = 30 cm • thickness = 130 mm • wall thickness 8.5 timesless than JET-X HEWmeas = 25 arcsec X-Ray test @ Panter-MPE (July ’02) - E = 1.5 keV

  11. Telescopes Features • Mass: 25 kg/module • Area: @ 1 keV= 150 cm2/module • HEW: 25” (@1,5 keV) • Mass: 59 kg/module • Area: @ 1 keV= 150 cm2/module • HEW: 15” (@1,5 keV)

  12. Enrico Costa-IASF-Roma INAF Effecttsive area and Possible improvements 5 telescopi invece di tre con Coating di Carbonio 5 mirrors C + Ir coating 3 mirrors Au coating (baseline) Altre alternative: 6 telescopi tutti leggeri Coating Ir + C 2 detector per telescopio

  13. GEM electric field The Gas Pixel Detector X photon (E) conversion GEM gain collection pixel ASIC E a 20 ns

  14. ASIC features • 0.18mm CMOS VLSI • 300 x 352 exagonal pixels, 50mm pitch • 15mmx15mm active area • Peaking time: 3-10 ms, externally adjustable; • Full-scale linear range: 30000 electrons; • Pixel noise: 50 electrons ENC; • Read-out mode: asynchronous or synchronous; • Trigger mode: internal, external or self-trigger; • Read-out clock: up to 10MHz; • Self-trigger threshold: 2200 electrons (10% FS); • Frame rate: up to 10 kHz in self-trigger mode • (event window); • Parallel analog output buffers: 1, 8 or 16; • Access to pixel content: direct (single pixel) or serial • (8-16 clusters, full matrix, region of interest); • Fill fraction (ratio of metal area to active area): 92%)

  15. mini-clusters of 4 pixels contribute to a local trigger with dedicated shaping amplifier • threshold < 3000 e- (10% FS) • individual pixel trigger mask • independent trigger level for each 16 clusters • event localization in rectangle containing all triggered mini-clusters + user selectable region of 10 or 20 pixels • the chip calculates the event ROI (Xmin,Ymin – Xmax,Ymax) for subsequent sequential readout of selected area Block diagram of the interface BE electronics Block diagram of the control electronics

  16. Sealed device(only clean materials, baking & outgassing) • GEM pitch: 50 mm • GEM holes diameters: 30 mm, 23 mm • Read out pitch: 50 mm • Absorption gap thickness: 10 mm • Collection gap thickness: 1 mm Collaboration with Oxford Instruments Analytical Oy (Finland)

  17. From the laboratory to a flight prototype is • With such a device we can perform simultaneously: • Imaging (~ 150 mm) • Timing ( a few ms) • Spectroscopy (~20% @ 6 keV) • + • High Sensitivity Polarimetry A sealedPrototype. Itweights 50 g + 30 g of PCB!

  18. Tracks reconstruction The same algorithm will be implemented in thePDHU 1) The track is recorded by Xpol 2) Baricenter evaluation Real track 3) Reconstruction of the principal axis of the track: maximization of the second moment of charge distribution 4) Reconstruction of the conversion point: major second moment (track length) + third moment along the principal axis (asymmetry of charge release) 5) Reconstruction of emission direction: pixels are weighted according to the distance from conversion point.

  19. 5.9 KeV unpolarized source 5.4 KeV polarized source The angular distribution of photoelectron tracks gives polarization degree and angle Modulation factor = (Cmax – Cmin)/ (Cmax + Cmin) ˜ 50% at 5.4 KeV Using the impact pointinsteadthan the centroid the resolutionismuchimproved

  20. Imaging capability 55Fe source Ne(50%)-DME(50%) Holes: 0.6 mm diameter, 2 mm apart.

  21. 5.4 keV polarised photons (Cr) 5.4 keV polarised photons (Cr)

  22. Modulation factor measured with two different gas mixtures: He/DME and Ne/DME @5.4 keV Cr-line energy 51.11%± 0.89% 54.26% ± 1.24% @6.4 keV Fe energy

  23. Not only MonteCarlo The modulation factor measured at 2.6 keV, 3.7 keV and 5.2 keV with XPOL has been compared with the Monte Carlo previsions. The agreement is very satisfying. 5.2 keV polarized photons for two angular rotations of the polarizer showing the good angular sensitivity.

  24. TC_01 Fe55 source TC_04 Environmental tests: thermal cycles and thermo-vacuum Test temperature range: between -15°C and +45°C 8 thermal cycles in a climatic chamber at atmospheric pressure with reduced humidity (<10% RH) and 1 thermo-vacuum cycle (P<10-4Torr) in the same temperature range. XPOL inside the climatic chamber(Angelantoni Challenge 1200) 2 thermocouples: TC_01 (on the readout board) and TC_04 (on top of the drift window Titanium frame) During test a Fe55 (Ø~ 1cm) illuminated the whole detector sensitive area

  25. Thermal cycles Tests at 15°C at the beginning and at the end of the cycles (reference tests) and at +20°C and +10°C (maximum and mimimum operating temperatures) The hot and cold data taking tests show a ~-2%/°C gain dependence.

  26. The thermo-vacuum chamber HV feedthrough Chip readout feed through Fe55 source PT100 on window PT100 on frame cryostat Thermo-vacuum A vacuum vessel (Ø~250mm) is mounted around the cold head of a CRYODINE cryostat and connected to a Varian 979 leak test system that can easily reach a vacuum pressure <10-4Torr. The detector is mounted on the aluminum flange screwed on top of the cryostat. A series of 6 x18W resistors is glued to the lower face of this flange. The resistors heat, in competition with the cryostat freezing, allows the system to reach a large range of temperatures.

  27. T frame T window Thermo-vacuum A single +45°C, -15°C cycle at P<10-4Torr was performed Fe55 source image at the beginning (top) and at the end of the thermo-vacuum cycle

  28. Detector OFF Peltier (+0.1W) ASIC Temp=7.1°C Analisi termiche preliminari • Detector ON (Q=0.5W) • Peltier (-0.4W) • ASIC Temp=9.4°C

  29. Modelli 3D e Analisi Preliminary structural and modal FEM analyses have been performed to design the XPOL board interface frame and the vibration vertical fixture (the plate fixture was supplied with the test equipment). CAD software: UGS I-Deas NX12 FEM software: ANSYS V11 The results, see below, show that neither the equipment nor the board with the interface frame have frequency modes below 2000Hz. These results have been confirmed by the vibration tests. Mesh data: Nodes=17557 Tetrahedral Elements=6738 XPOL Board and Interface Frame Assembly - Modal Analysis, 1st Mode, 2839Hz Fig. Vibration Test XPOL Board and Fixture Assembly 3D model

  30. Z axis Sine sweep test X axis For each axis we have performed a sine sweep between 20 and 2000Hz at 2oct/min and a random test 3dB for 75s over the predicted random vibration environment of the Pegasus rocket. In all the random tests the item was vibrated to an overall 3grms As foreseen by the FEM analysis no resonances are present in the 20-2000Hz range. No damages have been reported Z axis

  31. Heavy Ion Medical Accelerator in Chiba (HIMAC) P < 160 MeV He C NONeSiArFe Xe 500 MeV/n Fe beam 100-150 c/cm2/spill Spill = 3.3s repetition and 1.7s flat top 5 x 5 cm2 or s=5mm Gaussian shape beam At 50Hz, 1min of beam ~ 1year of exposure in space R = ∫F cosθ dΩ dE = 6× 10−5 cts/s/cm2

  32. Filter wheel • The purposes of using a filter wheel are: • Preserve the experiment & measure intrinsic background • Reduce the counting rate • Calibrate the experiment A filter wheel is already flown on board XMM : Filter wheel on-board XMM for the EPIC experiment

  33. To each position corresponds an operative mode: Open : Standard observation Closed : Internal Background gathering Diaphragm : Standard observation with rejection of strong sources in the field of view Beryllium filter : rate reduction at level of unprocessed data Calibration non polarized fluorescence source Calibration non polarized fluorescence source Calibration polarized (45o) Bragg diffraction

  34. Unpolarized calibration source : (A) Fe55 half life 2.73 yr Energy 5.89 keV (B) Cu fluorescence by Cd109 half life 1.27 yr 8.04 keV Polarized X-ray source : Composite Bragg diffraction (45o) From Graphite: PVC Fluorescence (2.6 keV) from Fe55 P = 99.9% From FLi 5.89 keV diffracted at 47.6o P = 87.9 % Composite polarized source: Bragg diffraction from stacked thin Graphite and LiF permits to polarize simultaneously 2.6 keV from thin PVC sheet fluorescence by Fe55 source and 5.89 keV by the same Fe55 source. Muleri et al 2007

  35. The Back End and Control Electronics • POLARIX electronics is hosted in four different types of units: • 3 Detector Assy electronics (FEE) • 3 Back End Electronics(BEE) • 1 PDHU Electronics • 1Pulse Per Second Generator (PPS Gen.) (NTH)

  36. Main BEE requirements: • Peak events rate up to 120 ph/(s*det) • Average rate 10 ph/(s*det) • Memory > 32k x 16 (in case of no global pedestal calculation) • 8-bit ADC and DAC • Upto 10Msample/sec ADC • Serial link < 1Mbit/sec • Dead time <3% w.r.t. average time between two events (i.e. ~3ms) • One HV DC/DC per detector. Three voltages needed in the range 0…3kV, carried out with a voltage divider.Sinked current is very low (few nA) Analog&Digital Processing Architecture

  37. ON-BOARD TRACK RECONSTRUCTION - 1/2 This algorithm implies several calculation loops including: • Calculation of the first, second and third moment • Inverse trigonometric functions • Two Change of coordinates • Exponential function • Square and square root calculation • Floating points multiplications and divisions The processor load related to the main algorithm operation loops has been evaluated for two space qualified devices: ERC-32 and DSP21020

  38. MASS MEMORY 1/2 The average net telemetry data rate is: 30 ev/sec x 1184 bit/ev = 35Kbit/sec. In case of strong sources: 200 ev/sec x 1184 bit/ev = 231 kbit/sec Assuming an entire day dedicated to observe strong sources, we get: 86400 sec/day x (231 - 35) kbit/sec = 2Gbyte This mass memory can be implemented in one PDHU board using the 3D-plus technology to package SRAM memory chips.

  39. Total Mass Budget 906 kg (included contigngency) Total Power Budget Service Module: 356 W Payload: 80 W Total: 523 W

  40. MISSION ANALYSIS1/ VEGA PERFORMANCES

  41. L’orbita LEO equatoriale permette di effettuare la comunicazione tra segmento-volo e segmento-Terra Polar-X in Banda S utilizzando la stazione di Terra ASI a Malindi. Come schema della rete di comunicazione, Centro di controllo missione e Centro delle operazioni scientifiche si potranno riprendere gli schemi già ampiamente collaudati nelle missioni nazionali (SAX, SWIFT, COSMO) Lo studio della architettura della stazione di terra sarà svolto da Telespazio, coinvolta nello studio con contratto di consulenza. Segmento terra

  42. Data rights and policy 1/2 • POLARIX is a PI mission but its scientific exploitation is open to the world community. • The POLARIX team will have the right to exploit exclusively data from SVP (1 month) and 25% of data from the Observing Phase. This 25% of time will be subdivided in observations organized in a Core Program, aimed to guarantee a baseline throughput of the mission. The POLARIX team will be supported in the definition of the CP and in the exploitation of data by scientists of the Italian Community. • The 75% of data of Observing Phase will be assigned, following an Announcement of Opportunity issued before the launch and open to the whole community. Guest Observer Teams will be allowed to apply for any source except those included in the core program. Both Core Program an Guest Observer Programs can include Target Of Opportunity Observations. After ascertained the feasibility of the observation the proposals will be submitted to a Time Allocation Committee and selected on the basis of their scientific quality.

  43. Data rights and policy 2/2 • Assigned data will be reserved to either the Team or the Guests for one year from the delivery. After one year the data will be put in an open access archive. • Guests will be supplied with a Guest Observer Handbook to prepare proposals and analyse data, with software tools, based on open source codes and documented and with all data needed for exploitation. The distributed data will be lists of qualified events including absorption point and time, energy and polarization angle, plus the data on coverage, time windows and dead time. All data will be accessible to POLARIX Team that will use them for health monitoring, calibration an to improve the software tools. The analysis of the tracks, the analysis of calibrations and the production of the response matrices of the instrument are a responsibility of the POLARIX Team. • A significant fraction of the analysis software is very similar to that of SAX and SWIFT and the scientific exploitation of POLARIX, will benefit from a multifrequency approach. Therefore a significant involvement of ASDC is foreseen. The terms will be fixed by the Science Management Plan (TBD)

  44. SCIENCE Testing General Relativity in Strong Field The plane of polarization should rotate with energy. This s an unique mark for the presence of a Black Hole. Inserire 1915+105 da articolo M. Dovˇciak, F. Muleri, R. W. Goosmann, V. Karas and G. Matt, 2008 submitted

  45. Sensitivity

  46. Angular Resolution: resolving the Crab

  47. The link of Polarimetry with Hard X-ray Astronomy A certain connection does exist between physics of hard X-ray emitters and expectations of polarization. Non thermal processes, can be singled out by the presence of hard tails (e.g. in some clusters and in some shell like SNR) but also from the existence of linear polarization. The latter also provides a geometric information (e.g. the orientation of magnetic fields or the direction of particle acceleration). Alternatively the presence of hard component and the absence of polarization can provide the evidence for disordered systems (e.g. disordered magnetic fields for synchrotron, or diffuse source of seed photons in an inverse compton). Because of these overlaps and because of a reduced mismatching of observing times, a polarimeter and a hard X-ray instrument can efficiently combine, resulting in a very performing mission. This is the case of HXMT of the Chinese Space Agency

  48. Another Option: HXMT POLARIX is not the only opportunity to fly a polarimetry pathfinder. Contacts are in progress between ASI and CNSA to harbor two telescopes with a polarimeter in the focus as piggy back devices aboard HXMT.

  49. X-ray polarimetry with HXMT The Hard X-ray Modulation Telescope Missionof the Chinese Space Agency • Three Major Instruments • HE: Sensitive in 20-250 keV. 18 Phoswich Detectors with a F.O.V. of 5.7°×1.1° FWHM Total area 5100 cm2. • ME: Sensitive in 5-30 keV 3 Si-PIN detector arrays with a F.O.V of 5.7°×1.1°. Total collection area 952 cm2. • LE: Sensitive in 1-15 keV. Swept Charge Devices. 3 arrays each with two kinds of FOVs, 5.7°×1.1° and 5.7°×2.2°, so as to study the cosmic X-ray background in this energy band. Total collecting area of LE is 384 cm2. Working Mode: Scan survey + pointed observation Orbit: 550 km 43° P/L: ~ 1000 kg

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