High spectral resolution microcalorimeters for X-ray

astrophysics

High spectral resolution microcalorimeters for X-ray

astrophysicsL. PiroL. Piro

IASF/INAF-Roma

High resolution X-ray spectroscopy with ucalorimeters

plasma emission (107K) observed with:

* Next generation (TES) ucal (E=2 eV: XEUS, Con-X)

*present generation ucal (E=6-8 eV: ASTROE-2)

*CCD (E=100 eV:XMM)

Dark matter & WHIM: X-ray forest

Structure simulation from Cen & Ostriker (1999)

Simulations of WHIM absorption features from OVII as expected from filaments (at different z, with EW=0.2-0.5 eV) in the l.o.s. toward a GRB with Fluence=4 10-6 as observed with ESTREMO (in 100 ksec). About 10% of GRB (10 events per year per 3 sr) with 4 million counts in the TES focal plane detector

Study of local and intergalactic medium in primeval galaxies with GRB with XEUS

• The Fe line in a GRB like GB970508 but at z=5

• Study of the metallicity of the ISM of a host galaxy of a GRB at z=5 through X-ray edges

How a microcalorimeter works

R

T

TES

T

RGe-NTD

C R

JFETC

X photon of energy E

G

Tbath

RsC R

SQUID

L

I

V

T

E/C =C/G

t

Sensor typeElectronic coupled

device Output Signal

=IA T (R/T)

=IA T (1/T)

Why TES ucalorimeter

• TES (Transition Edge Sensor) microcalorimeters as focal plane instrument:– spectral resolution (DE<2 eV at E<1 keV) andand– high count rate (pulse duration=100 usec vs a few

msec of semiconductor microcalorimeters): use as focal plane for large telescopes/high count rates

• Baseline in most of future X-ray missions

Missions (in various stages) with (TES) microcalorimeters

• Europe: XEUS (ESA), ESTREMO(I+int. partners), WHIM mission (Holland)

• Japan-US: ASTROE2 (semiconductor): launch: mid 2005

• US: Con-X(possible merging with XEUS), SMEX proposal for WHIM

• Japan: NEXT, DIOS (WHIM)

Scientific drivers

– Evolution of cosmological structures and sources in the Universe: X-Ray Cosmology: GRB as beacons, WHIM and dark matter, formation of first structures in the Universe

– Extreme physics (e.g. test of general relativity in Black Holes, GRB engines and progenitors)

Science: ESA AWG recommendation• Theme 2: The early Universe: Observing the Universe taking shape• The goal is to map the cosmic history back to the time when the first luminous sources ignited, ending the dark ages of the Universe by reionizing

most of its atoms, after which galaxies and their supermassive black …. The first priority is a new generation X-ray observatory that should be able to observe clusters of galaxies back to their formation epoch, as witnesses of large-scale structure formation, the heating of the intracluster gas, its relation to the evolution of the cluster galaxy population, the impact of AGN activity on the intracluster medium, and its chemical enrichment; to detect the missing half of the baryons in the local Universe, most likely hidden in the warm-hot intergalactic medium (WHIM), through soft X-ray spectroscopy; to find the earliest indications of AGN activity, characterize its relation to star formation and galactic assembly, and locate the mergers of supermassive black holes expected to be detected by LISA Therefore, the AWG strongly and unanimously recommends the development of an X-ray observatory with a fast-track development to ensure its operation to at least partially overlap with the operation of LISA.

• Theme 3: The evolving violent Universe • …. probing deep inside the gravitational well of black holes and neutron stars, providing for the first time a thorough test of general

relativity in the strong field limit, and deals with the physics of strong interactions in ultradense environments, the virulent processes in hypernova explosions leading to Gamma Ray Bursts, and binary black hole mergers.

•  • For the very first part of the 2015-2025 decade, two observatory-class missions are recommended:       a high throughput, high angular, spectral and time resolution telescope in the X-ray domain for the detection and

detailed study of the imprints of the evolution of the Universe, especially those triggered by violent events. The AWG also gives high priority to the continuation of the present technology program for this project, and strongly and unanimously recommends that all steps be taken to ensure that such a mission can be flown as early as possible in the 2015 time frame.

•  

Instrument Goals

• Expected spectral resolution: 2 eV @ 6 keV, 1eV @<1 keV

• Status of the art today: around 3 eV at 6 kev (SRON, Goddard,NIST), 2 eV at E<1 keV. Moderate imaging with about 30 pixels

• Goal (XEUS): imaging with 1000 pixels spectral resolution and count rate as already achieved with a single pixel (typical size 200um)

• Rate: 100-300 cts/s/pixel• Bandwidth: 0.2-10 keV

The Italian collaboration on TES • INFN-Uni Genova (F. Gatti et al): TES development, manufacturing and tests.

– Facilities for TES manufacturing, cryogenics; – Personnel: 5 researchers, 3 technicians

• IASF-Roma (L. Piro et al) : implementation of TES for X-ray astronomy, calibrations, simultations, trade-off studies. – Facilities for TES measurements (cryogenics, clean room..)– Personnel: 3 researchers, 1 technician

• A project for TES development by IASF-Roma & Uni-Genova has been recently approved by the Minister of Uni, Research & Tech + Descartes prize (IASF): budget of about 0.5 Meuro in 3 year

• IFN-(CNR/Roma) (R. Leoni, G. Torrioli et al.): SQUID readout: design, prototype manufacturing, tests– Facilities for SQUID manufacturing– Personnel: 4 researchers

• collaboration with Uni-Roma I (P. De Bernardis et al.) on TES for microwave astronomy

Microcalorimeter roadmap in Italy

• Microcalorimeters are identified as one of the primary R&D activity in the strategic plan for HE Astrophysics jointly prepared by IASF,INAF & INFN in response to a call on a HE space plan from ASI

• The plan includes a mission (ESTREMO: Extreme phySics in the Transient Evolving cosMOs ) employing TES ucalorimeters

Our FacilitiesTES manufacturing:– Thin film production: 1 thermal evaporator, 1 e-gun

evaporator Magnetron spattering, Pulsed Laser Deposition system, Ion beam (for cleaning and etching)

– 1 RIE system with optical diagnostic for end point detection

– Small clean room (class 1000) with micro-lithographic facilities (Ge).

• Detector characterization for X-ray space missions: – 3 dilution fridges + 1 ADR and related electronics…

(Ge); 1dilution– 1pulse tube/ADR (IASF-Rome) with external access for

calibrations in x-ray beam facility – Clean rooms for integrations

• SQUID – Clean room and equipment for SQUID manufacturing

(IFN-Rome)

International collaborations

• Given the common goal (XEUS, other missions) and the know-how, and considering the startegical importance of developing an European leadership in the field, we have started a collaboration with SRON on the detector and read-out since 2003

• Broadening to a European consortium (meeting in SRON,Oct.2004: Finland, France, Germany, Holland, Italy, Spain, Switzerland, UK, )

Milestones of the Ge-Rm project

• 2004-5: manufacturing and testing of single pixels ucal for astrophysical application (planar geometry with all thin film technology). Design of pixel array TES prototype. Study of low-heat capacity absorbers (to improve the spectral resolution). Design of SQUID multiplexing schemes for read-out

• 2005-6: prototype testing, modelling, selection of the techniques for TES+SQUID arrays

• 2006-7: final prototype (4x4) manufacturing and testing

TES microcalorimeters

TES

Al-Ag multi-layer

High purity Si glued on a Sn absorber

Electro – thermal links to the heat bath

Polycrystalline Sn energy

absorber

We are developing, in collaboration with Genova University (decennal experience in developing microcalorimeters for basic physics), TES devices with the goal of conforming to XEUS specs

First prototype (not optimized for Astrophysical measurements): Absorber:300umx400um Sn absorber (25um thickness)

Sensor: Ag-Al-Ag-Al Multi-layered and lithographed film

Silicon substrateAl-Ag Multi-layer

80 nm Ag 40 nm Al 5 nm Ag 5 nm Al

Effects limiting resolution performances:

1) Volume detector

2) Read-out based on limited bandwidth SQUID (50 kHz) needing signal attenuation (hence S/N degradation)

Prototype of detector for astrophysical application

• TES Ir-Au (1000-200 A) strip length/width=5mm/10um, size=100u

• Wafer Si 125um thick• Different Manufacturing techniques:Pulse

Laser Deposition, Electron Beam Evaporation, different sensor patterns

• Absorber: 25u Sn polycrystalline, 400 um size. Improvements with pure sn crystal

• Large bandwidth SQUID

0

200

400

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2400

82,5 82,6 82,7 82,8 82,9 83 83,1 83,2 83,3 83,4 83,5 83,6 83,7 83,8 83,9 84

T(mK)

R(m

oh

m)

Measurements

Rvs T transition

Bias voltage: 2nV, peak signal: 2.3 V (Fe line), noise 1mV rms. Resolution: better than 6eV

Preliminary spectrum

Steps towards a European ucal

• Further improvements on spectroscopy performances ( 2 eV) (physics of detector, noise, geometry, deposition tech.)

• Imaging: – SQUID uplexed read-out (Frequency), cold

electronics for feedback– Alternartive routes: POST (heat division), jfet

• New techniques (magnetic ucal)