"The Extreme sky: Sampling the Universe above 10 keV" IXO TES Microcalorimeters: from Focal Plane instruments to Anticoincidence Detectors Claudio Macculi, Luca Colasanti, Luigi Piro INAF/IASF Roma 13th - 17th October 2009 Otranto (Lecce) Italy, Castello Aragonese Italian collaboration Piro Luigi Morelli E. (IASF-Bo) Colasanti L. Rubini A. Macculi C. Mastropietro M. (CNR/ISC) Natalucci L. Lotti S. Mineo T. Barbera M. La Rosa Perinati E. Gatti F. Ferrari L. + Tech. personnel Bagliani D. Torrioli G. Bastia P. Bonati A. Outline • • • • • TES microcalorimeter: working Principle Cryogenics and Readout electronics Detector Sizes, Single Pixel and Array results IXO X-ray Microcalorimeter Spectrometer Cryogenic AntiCoincidence Detector • Preliminary Test • • Conclusion Future: CryoAC as Hard X-ray ray detectors? TES microcalorimeter: working Principle …used from Microwave to soft-Gamma ray domain... T dR R dT The X-ray micro calorimeter consists of a: • X-ray absorber (CABS) • temperature sensor • a thermal link (G) that connects the absorber to a heat bath A thermal bath to keep the absorber's temperature constant is necessary (restore the Working Point) Photon absorption Absorber temperature change Change in TESresistance. Since the TES is Voltage polarised Change in current Weak currents (also < μA), low TES Resistance (~ 0.1 Ohm) a special lownoise current amplifier is required SQUID Amp. (Superconducting Quantum Interference Device Amplifier) 2 VTES dT (t ) C G[T (t ) Tb ] E (t ) dt RTES [T (t )] t E ETF T Tb e C T R I Electro-Thermal Feedback – Energy Bandwidth – Energy Resolution C th G ETF th 1 L Tb TTES ETF T L 1 b n TTES n th th 1 n The Joule heating produced by Voltage bias PJ = V2/R: if T R PJ R Electro-Thermal stability Moreover: strong reduction of the decay time constant fast signals high count rate (bright sources or big area optics) En. Bandwidth EMAX CT 0.63 En. Resolution EFWHM 2.35 1 Attenuation of thermal bath temperature fluctuations kT 2C kTEMAX High En. BW High C, Low alfa (wide transition) High En. Res. low T cryogenic detector low C high alfa (narrow transition) Trade off is necessary to reach the wanted performances Tb/TTES Cryogenics and Readout electronics Readout electronics: Cryogenics: 3He/4He mixture (working on phase separation) few-10 mK base temperature (tens to hundred μ[email protected]) 4He Pulse tube + ADR (ADR works on paramagnetic salt demagnitazion) about 30 mK base temperature (3 μ[email protected] for 20 h operation) Temp. stability: about 10 μKrms (several hours) 3He fridge insert (Kelvinox) SQUID (micro-machined device): Magnetic flux is generated by TES-current flowing in a coil coupled to the SQUID. Such a flux crosses the Josephson junction where it is transformed in Voltage. Noise: few pA/rtHz up to some MHz bandwidth Bias Power: few nW Vericold ADR system Supracon Cold finger Niobium can for magnetic shielding Magnicon Detector Sizes and Single Pixel results TES on silicon membrane (tech. used for the Array): - Ir/Au, Ti/Au or Mo/Au (total thickness about 1E+2 nm) onto SiN (1 um) suspended membrane (TES area depends on the pxl area) - Absorber (Au, Au/Bi, Cu/Bi, Sn, few um thick) growth on the TES substrate - Pixel about 250x250 um EFWHM = 3.6 eV INFN and Genova Univ. Ferrari, Gatti et al. INFN and Genova Univ. TMU-ISAS SRON Hoevers et al., J Low Temp Phys, 151, (2008) Akamatsu, LTD13, in press, (2009) Bandler et al., J Low Temp Phys, 151, (2008) What about the Array? Multiplexing technique is necessary to minimize the heat load caused by thermal conduction through the harness to the cold finger (thousand wires). The array is powered and read by rows or by columns using different Multiplexing methods: 32x32 NASA GSFC – IXO/XMS • FDM (sinusoidal excitation) (bond pads for 256 channels only) • TDM (switch ON/OFF line by line) • CDM (inversion bias polarity) FDM technique: • Pixels are AC-biased (line by line) • Summing node (column by column) • De-modulation by the same frequency to recover the pulse Eckart, Doriese, SPIE Newsroom , 2009 IXO X-ray Microcalorimeter Spectrometer IXO consortium-CoPI NASA/GSFC, SRON, ISAS-JAXA, INAF/IASF Roma Central, core array: Layout wich fits the IXO Reqs. – Individual TES – 42 x 42 array with 2.9 arc sec pixels – 2.0 arcmin FOV – 2.5 eV resolution (FWHM) – ~ 300 sec time constant – 0.2-10 keV Outer, extended array: – 4 absorbers/TES – Extends array to 5 arcmin FOV – 52 X 52 array with 5.8 arcsec pixels – <10 eV resolution – <2 msec time constant Inner Pixel: ~ 300x300 m2 Outer Pixel: ~ 600x600 m2 Absorber: Bismuth 7 m Cryogenic AntiCoincidence Detector • • • • Bkg requirement: 2·10-2 cts cm2 s-1 keV-1 Without AC: at least 10 times larger (from preliminary simulation only GCR accounts for 0.15 cts/cm2/s/keV) Requires an AC with > 95% rejection efficiency AC need to be < 1mm near to the TES Cryogenic detector Rej eff. = 99% D < 1mm TES-Array: Cryo-AC MIP Events to be rejected CryoAC Design We decide for TES-based Cryo AC made of Silicon due to the experience inside our collaboration • • • • • Baseline Geometry: Assembly of 4 sub-unit Detector technology: TES, the same of the focal plane instrument simplification of the Electrical, Mechanical and Thermal I/F ( increase reliability the TRL) DT Analysis (Cosmic ray flux plus soft protons from mirrors plus Solar flare): – 5% DT To be conservative CryoAC “Total recovery time” < 500 μs – Without Solar Flare, a DT = 1% corresponds to a “Total recovery time” up to 1 ms – “Total recovery time” to be compared with the TES-Array time constant Expected maximum deposited energy ~ 4 MeV CryoAC Energy Bandwidth: 0.5-1 MeV (to increase BW solving the saturation trade-off with the time constant and Dead Time) Suppose up to 300 μm thick about 90 keV released from MIP. At least S/N > 10 Emin = 5 KeV CryoAC Different thickness EMAX and Eth(Epr) if Eth(Epr) > EMAX Saturation 18 mm 18 mm TES Array 30 mm Thickness (μm) Emax (MeV) Saturation Range Primary pr En. (MeV) 100 0.4 0.9-15 150 0.6 1.05-15 200 0.8 1.2-15 250 1 1.4-15 300 1.2 1.6-15 IXO-CryoAC Prototype measurements: Preliminary Test Thickness = 300 um Produced at Genova University 3.3 mm ABSORBER Si n-type: 16-27 ohm*cm A ~ 16.5 mm2 TES Iridium V = 3.7mm2 x 90nm 5 mm Illumination hole EMAX ~ 450 keV SQUID 55Fe Source setup Results: Fast signals and low energy events detected 55Fe Source Ib = 650 uA Amplitude Variance under investigation PH E CT I bias Conclusion Results from a detector of C ~ 16.5 pJ/K and A ~ 16.5 mm2 (~ x200 usual pixel area): 1. 2. 3. Events from 55Fe detected Fast Rise time ~ 2 μs Fast Decay time ~ 100 μs for near null ETF we got Fast signals (D TES array ~ 300 μs) NOT FAR FROM THE GOAL Next future Further Investigation for amplitude Variance Test on 10x10 mm2 pixel, 50 μm thick (V ~ 5 mm3) Same Volume of the present detector but 6x in Area (final size 18x18 mm2) It is also foreseen to use 241Am (~ 5.5 MeV) to study the saturation regime (Dead time) Future: CryoAC as Hard X-ray ray detectors? Already exists TES-detector with E/dE > 2000 at 60 keV adopted for nuclear materials analysis Tin bulk absorber (~ 1x1x0.25 mm3) by-layer Mo/Cu TES D.T.Chow et al., Proceedings of SPIE Vol. 4141 (2000) TES: 200 nm thick [email protected] (expected ~ 23 eV) TES 400 μm square W.B. Doriese et al., J Low Temp Phys (2008) 151 Ciao!