R&D on CdTe pixel detectors J. Alvarez, J.L. Galvez, M. Hernanz, J. Isern

Transcription

1 R&D on CdTe pixel detectors J. Alvarez, J.L. Galvez, M. Hernanz, J. Isern on behalf of a large collaboration with IMB(CNM-CSIC) and IFAE LOFT Large Observatory For x-ray Timing M. Hernanz, J. Alvarez, A. Caliandro, J.L. Galvez, J. Isern, N. Rea, D. Torres Instituto de Ciencias del Espacio (CSIC-IEEC)

2 Explomev project The EXPLOMEV project was approved and funded by Spanish Ministry of Science ( ) The goal of the technological part of this project is the research and development of a gammaray spectrometer with imaging and polarimetry capability and optimal spatial and energy resolution in the energy range of nuclear lines (from few hundred kev up to few MeV). Perspective: R&D of a high performance focal plane detector based on room temperature semiconductor detectors (CdTe/ CZT) for the next generation of hard X and soft gamma ray telescopes based on Laue lenses. GRI DUAL-2010 Currently: Design and development of a CdTe/CdZnTe pixel detector array for polarimetry. Considered as a payload option for a balloonborne experiment with a CdTe/CdZnTe polarimeter, currently under study.

3 A Balloon-Borne 3D CZT(CdTe) Scattering Polarimeter for Hard X-Ray Astrophysics Heritage CIPHER: coded imager and polarimeter for high-energy radiation E. Caroli et al. NIMA, Vol 448, (2000) Meeting, February 2011, Barcelona Detector requirement for a reliable measurement of the CRAB polarisation state. High energy sources to be observed. Study of the CZT(CdTe) detector configuration to improve polarisation sensitivity. Gondola requirement (e.g. pointing accuracy and stability). Other partner. Proposal organisation and tasks/responsibilities sharing.

4 A Balloon-Borne 3D CZT Scattering Polarimeter for Hard X-Ray Astrophysics E. Caroli 1, J. M. Alvarez 2, N. Auricchio 1, C. Budtz-Jorgensen 3, R.M. Curado da Silva 4, S. Del Sordo 5, J. L. Galvez 2, M. Hernanz 2, J. Isern 2,I. Kuvvetli 3, J. M. Maia Pereira 6, J. B. Stephen 1, A. Zappettini 7 1 INAF/IASF-Bologna, Bologna, Italy 2 IEEC-CSIC, Instituto de Ciencies del Espacio, Barcelona, Spain 3 DTU Space, Copenhagen, Denmark 4 LIP, Coimbra, Portugal 5 INAF/IASF-Palermo, Palermo, Italy 6 Physics Dept., University of Breira Inerior, Covilha, Portugal 7 IMEM/CNR, Parma, Italy It is widely recognized that a measurement of the polarization of the high energy emission from cosmic sources is a key observational parameter which will aid in the understanding of the nature of high energy cosmic ray astrophysics. Therefore new instrumentation operating in this energy range should exhibit a good sensitivity also for this type of measurements. Herein we present the concept of a small high performance detector optimized for polarimetry between 100 and 500 kev suitable for use with stratospheric balloon-borne payload dedicated to obtaining accurate measurements of the polarization of the Crab pulsar. The detector with 3Dspatial resolution is based on CZT spectrometer sensitive units in a highly segmented configuration suitable for operation as a high quality scattering polarimeter. We describe recent development results and possible improvement currently under study. The proposed payload can be also considered as a pathfinder for a high performance focal plane detector for the next generation of hard X and soft gamma ray telescopes based on Laue lenses.

5 A Balloon-Borne 3D CZT(CdTe) Scattering Polarimeter for Hard X-Ray Astrophysics Balloon-borne payload option CdTe/CdZnTe pixel detector array for polarimetry Background Studies

6 Balloon-borne payload option Incomplete charge collection in CdTe Simulated Pulse Height spectra with Geant4 Hecht equation Planar Transverse Field (PTF) configuration Focal plane detector of a Laue lens - Caroli et al, Experimental Astronomy, 20, 341 (2005)

7 Balloon-borne payload option CdTe/CdZnTe pixel detector array Geant4 model Planar Transverse Field (PTF) configuration Background Studies Focal plane detector of a Laue lens - Caroli et al, Experimental Astronomy, 20, 341 (2005)

8 Design of the pixelated CdTe prototype GR HV bias CdTe array 11x11 Dimensions: 12.15mm x 12.15mm x 2mm The pixel size: 1mm x 1mm Guard ring: 1 mm Structure: Pt//CdTe//Pt ( collection (Ohmic contacts for electron On the pixel side: Au/Ni/Au Manufactured by Acrorad (Japan) Pitch adapter board Fanout board - Glass substrate with metal tracks to connect the 121 pixels to the readout chip channels. - Mechanical support

9 Fabrication of a pixelated CdTe prototype Ni-Au deposition in the fanout to ensure the good bump bonding connectivity. Zoom of the fanout s pads ASIC NUCAM FAILED SUCCEED Fabricated in the IMB(CNM-CSIC) clean room Two masks required: Metallisation and Passivation Stud Bump Bonding process in collaboration with RAL (UK) Au pad on CdTe CdTe Fanout Ni-Au on Au pad Au Stud s on Ni-Au-Al pad Ni-Au-Al pad

10 First pixelated CdTe prototype CdTe pixel detector with the NUCAM ASIC low-noise read-out NUCAM ASIC developed by RAL (UK) Low Noise 128-Channel ASIC CdTe ASIC NUCAM NUCAM ASIC Two dynamic ranges (200keV, 350keV) On-chip ADC with 12 bits resolution. Leakage current compensation (adjustable): up to 4 na. Noise level: <100e- rms@2pf (Shaping Time=7.5µs) at room temperature. Threshold level( adjustable):10kev -40keV range. Shaping time: 0.5µs - 7.5µs range. Power consumption/channel ~2 mw at max RW rate (min rate 10kHz) NUCAM ASIC P. Seller et al,ieee Nuclear Symposium Conf. Rec., vol 6, pp , 2006 Ins$tuto de Ciencias del Espacio (CSIC IEEC) AstroMadrid, 30th June 2011

11 Test of a pixelated CdTe prototype T=-10ºC Bias=-400V 356keV -> 2.6% 59keV -> 9.2% Ongoing studies on the performances: Noise determination (Leakage-current measurement). Charge sharing. Correction of the Incomplete Charge Collection. J. Alvarez et al. NIMA 623,434 (2010), J. Alvarez et al. SPIE, 7732 (2010) Ins$tuto de Ciencias del Espacio (CSIC IEEC) AstroMadrid, 30th June 2011

12 CdTe/CdZnTe pixel detector for gamma-ray spectrometry with imaging and polarimetry capability in astrophysics J. M. Alvarez 1, J. L. Galvez 1, M. Hernanz 1, J. Isern 1, M. Lozano 2, G. Pellegrini 2, M. Chmeissani 3, E. Caroli 1,R.M. Curado da Silva 4 1 IEEC-CSIC, Institut de Ciencies de l'espai, Barcelona, Spain 2 Centro Nacional de Microelectronica (IMB-CNM(CSIC)), Barcelona, Spain 3 Institut de Fisica d'altes Energies (IFAE) 4 INAF/IASF-Bologna, Bologna, Italy 5 LIP, Coimbra, Portugal Gamma-ray astrophysics in the MeV energy range plays a crucial role for the understanding of many exciting cosmic phenomena such as stellar explosions or cosmic accelerators (e.g., Supernovae, Novae, Supernova Remants (SNRs), Gamma-Ray Bursts (GRBs), Pulsars, etc). Cadmium Telluride (CdTe) and Cadmium Zinc Telluride (CdZnTe) are very attractive materials for gamma-ray detection which have a great potential for imaging, spectroscopy and polarimetry in instruments onboard current gamma-ray space missions (such as IBIS/ INTEGRAL and BAT/SWIFT). However, the energy coverage of these instruments has been limited up to a few hundred kev, and there has not been yet a dedicated instrument for polarimetry. Our technological activities aim to develop a gamma-ray spectrometer based on CdTe/CdZnTe detectors, with imaging and polarimetry capability, for astrophysical applications within the energy range from a few hundred kev up to a few MeV. After developing and testing an initial prototype based on CdTe bidimensional segmented anode, performance studies are being carried out in a customized vacuum chamber with a cooler that allow us to control the detector temperature down to -30C. Results of these measurements are reported here. Additionally, the design of a CdTe/CdZnTe pixel detector array for polarimetry are presented. This design is one of the options for a balloon-borne experiment with a CdTe/CdZnTe polarimeter, currently under study (E. Caroli et al. in these proceedings).

13 A Balloon-Borne 3D CZT(CdTe) Scattering Polarimeter for Hard X-Ray Astrophysics Instrument option CdTe/CdZnTe pixel detector array for polarimetry Background Studies

14 Background Studies Measured and simulated background in the Nuclear Compton Telescope (E.Boggs et al.) balloon flight (NASA s Balloon Payload). The powerful simulation tools developed for Advanced Compton Telescope and used in this experiment is available at the Institute of Space Science (CSIC-IEEC). CLAIRE balloon flight 2002 (P. von Ballmoos et al.)

15 R&D on CdTe pixel detectors J. Alvarez, J.L. Galvez, M. Hernanz, J. Isern on behalf of a large collaboration with IMB(CNM-CSIC) and IFAE LOFT Large Observatory For x-ray Timing M. Hernanz, J. Alvarez, A. Caliandro, J.L. Galvez, J. Isern, N. Rea, D. Torres (CSIC-IEEC) Instituto de Ciencias del Espacio (CSIC-IEEC)

16 LOFT is a medium-class mission selected for the assessment phase of the ESA M3 Cosmic Vision call currently in a LOFT meeting in ESTEC

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19 ESA s Soil Moisture and Ocean Salinity (SMOS) satellite Launch November 2009-

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22 LOFT s Wide Field Monitor (WFM) Meeting 21th-22th June, Barcelona

23 Geant4 simulations of a WFM unit Effective Area Mask (300 x 300 mm) Tungsten : 150um 50% open area 10um Al (see mass model) Field of view one WFM-Unit Collimator: (support + shielding) Carbon Fibre : 1mm Tungsten : 150um Detector (200 x 200 mm) Silicon : 450um Coating : Al (10 um) Backshield 1 : Al 1mm (radiator) Backshield 2 : W (200um) E = 10keV Vignetting

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