Advanced T High ENergy Astrophysics LTD16...

ATHENA : the Advanced Telescope for High ENergyAstrophysics

ATHENA Italian Team, LTD16, Grenoble, July, 20-24, 2015 1

The Cryogenic AntiCoincidence detector for the ATHENA X-IFUinstrument: results from the design performed by GEANT4

simulation, and characterization of the new single pixel prototype asbasic-element of the fnal 2x2 array.

Centre de Congrès WTC, Grenoble, FranceJuly 20th - 24th 2015

C. Macculi, A. Argan, M. D'Andrea, S. Lotti, L. Piro,M. Biasotti, D. Corsini, F. Gatti, A. Orlando, G.

Torrioli

LTD16 Conference



Outline

• From science goals to technologies def inition: the need for the CryoAC

• GEANT4 simulations impact on design

• Preliminary characterization of the AC-S7 prototype

• Summary



Ariane V (VI ?) class launcherSatellite mass ~ 5500 kgPower ~5600 WFocal length: 12 mLifetime: 5 years (10 years)Nandra et al. 2013 arXiv1306.2307

The Athena Observatory: 1 telescope for 2 instruments!

Wide Field Imager: E: 125 eVField of view: 40’ x 40’Rau et al. 2013 arXiv1307.1709

Silicon Pore Optics:Effective area: 2m2 @ 1 keVPSF (HEW): 5’’Willingale et al. 2013 arXiv1308.6785

X-ray Integral Field Unit: E: 2.5 eVField of view: 5 arcminLarge array of TES cooled at 50 mKBarret et al. 2013 arXiv:1308.6784



Parameter Value What it def ines Main science drivers

Background level <5E-3 count/s/cm2/keV

Def ines the anti coincidence performance and the passive shielding

of the detector

Matter assembly in clusters - Metal production and dispersal - low surface brightness objects

X-IFU: from the science goals to the technologies def inition

INAF/Ge. Univ./CNRThe CryoAC

Energy bandwidth: 0.2-12 keV

This residual particle bkg level calls for the necessity of anactive anticoincidence very close to the main TES array

needs of a Cryogenic AntiCoincidence detector



The CryoAC for enabling X-IFU science about faint and diffuse sources

Size: 5.2 cm2 (in 4 pixel, each ~1.3 cm2, no Multiplexing

Thickness: 500 μm

Distance from X-IFU: < 1 mm

Rise Time constant: < 30 μs

Time constant Decay: < 300 μs (Goal)

Bandpass: 20 keV – 0.5 MeV

2K outerstructure

Cryoperm shield 2K

0.3 K supportingstructure

< 1 mm

Credits, Henk van Weers (SRON)

Minimum detectable f lux

Lotti et al., A&A 569, A54 (2014)

x 20

x 6



Geant4 impacts on the CryoAC design

Old baseline

New baseline



The X-IFU schematicsThe CryoAC is an instrument inside another

instrument

- 4 pixels made of Silicon absorber sensed by Ir TES.Tbath = 50 mK

- CFEE: SQuID + RF f iltering* SQuID (from VTT): We adopt a single stage SQuID,

SeriesArray, at 50 mK* RF f iltering at 2K to reduce EMI towards the FPA- WFEE (1 board-for-4 pixels) it biases the CryoAC pxl

and theSQuIDs; standard FLL- WBEE (2 boards: N + R) will process the analog

pulses from theWFEE, and HK to the ICU; No VETO onboard.It manages the WFEE in diagnostic mode (FLL, V-

PHI,test pulses...).



CryoAC design and mechanical I/F with the TES arrayWork started with the SRON team, shared ideas and preliminary size of the CryoAC active area (silicon

absorber) which will contribute to the FPA design, to be updated by GEANT4 vs Mass Model

Credits Henk van Weers (SRON), preliminary



The last CryoAC single pixels prototypes2 samples produced, with and without Al-f ingers (the former to

increase the A-thermal collection eff iciency)

65 TES each in parallel conf iguration

Absorber Silicon size: 10x10 mm2, 380 μm thick

TES (x 65) Iridium size: 100x100 um2, ~ 200 nm thick

Niobium wiring: ~ 870 nm thick

Silicon wafer 5-10 ohm cm

AC-S7AC-S8

TES

Nb wiring

Al f ingers



Preliminary characterization of AC-S7(65 TES in parallel conf iguration, no Al f ingers): Transition

measurement

Transition measurement has been performed at diferent labs, by diferent techniques and refrigera-tors

(Dilution and ADR): narrow transition (DT = 2 mK), and a critical temperature of Tc ~ 125 mK close to what

expected for Iridium thin f ilm.

This test consolidates the manufacturing processes for the pixel develop-ment!



Summary

• The TES-based CryoAC enables most of the ATHENA science goal reducing theresidual particle bkg, its development is framed in the X-IFU instrument

• The CryoAC is an independent instrument (detector + cold/warm electronics), sharing the same FPA with the scientifc TES-array instrument

• The Geant4 toolkit has been used to design the CryoAC in order to get the sciencegoals: Silicon absorbers in planar confguration, gap between pixel < 50 um, ~5 cm2 area

• Produced 2 new single pixel prototypes: wide area (~cm2), with and without Al-fn-gers. The transition measurement performed at diferent labs, with diferent techniquesand refrigerators it’s consistent. This result consolidate the manufacturing processes

• We plan to illuminate the pixel by the 241Am-60 keV line to probe its response (timing, A-thermal collecting efciency, energy spectrum, threshold…etc…)



h~50 um, l~500 um G~2x10-6 W/K



Conclusion

• The development of a TES based cryoAC detector is framed in the ATHENA X-IFU ins-trument to actively reduce the residual particle bkg, so enabling most of the ATHENAscience goal

• The CryoAC is an independent instrument (detector + cold/warm electronics), sharingthe same FPA with the scientifc TES-array instrument

• The Geant4 toolkit has been used to design the CryoAC in order to get the sciencegoals: Silicon absorbers in planar confguration, gap between pixel < 50 um

• We have produced 2 new single pixel prototypes, wide area of cm2, with and withoutthe Al-fngers. The transition measurement has been performed at diferent labs, by dif-ferent techniques and refrigerators (Dilution and ADR): it’s the same. This result consolidate the manufacturing processes of the detector.

• We plan to illuminate the pixel by the 241Am-60 keV line to probe its response (timing, A-thermal collecting efciency, energy spectrum, threshold…etc…)

Advanced T High ENergy Astrophysics LTD16...

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