ATHENA+

Microcalorimetri criogenici a transizione di
fase superconduttiva per il futuro
osservatorio spaziale in raggi X dell'ESA:
ATHENA+
Dott. Luigi Piro, Claudio Macculi
INAF/IAPS-Roma
Via del Fosso del Cavaliere 100
Outline
• Satellite mission + (very) brief scientific
overview
• High Energy italian TES Consortium
• TES microcalorimeter: working Principle
• The CryoLAB @ INAF/IAPS Roma
• Past LAB2 results
• Today LAB2 proposal
Aim of our activity
“The Hot and Energetic Universe” is the scientific theme recently (on
December!) approved by the ESA SPC as the guideline for a
Large mission to be flown in the next ESA slot (2028th) timeframe.
Yesterday, ESA issued the “Call for mission concepts for the Largesize “L2” mission opportunity in ESA’s Science Programme”
Æ ATHENA+ is a space mission proposal tailored on this scientific
theme: the X-ray community will entry in the “Integral Field
Spectroscopy” Å
Our (INAF/IAPS) activity borned ~ 10 years ago around high
resolution (dE/E<0.001@6keV) X-ray spectrometer-based mission
proposal, but today I will present the activity related to the last one:
the ATHENA+ X-IFU instrument!
ATHENA+:
Advanced Telescope for High ENergy Astrophysics
Lo strumento criogenico di piano focale per spettroscopia X
basato sui TES (1 kPixel)
Il rivelatore per anticoincidenza e’ basato sui TES (L2 orbit)
The science: High-z cluster, popIII by GRB, WHIM,…
Science Drivers
5 arcmin
The WHIM: the missing baryon issue

CMB, BBN, SN-1A Æ ΩB ~ 0.05
0 < z ~< 2 only 50% has been observed
50% “should be” inside the WHIM (T ~ 106 K and ρWHIM/ρc ~ 20)
The WHIM traces the DM, and it is the bridge among galaxies and clusters
No signature in Ly-α (H neutral) in absorption since the medium is highly ionized,
but in metals in soft-X band Æ E/dE > 1000.
IT IS FUNDAMENTAL TO MAP AND TO DO HIGH RESOLUTION SPECTROSCOPY
These regions are diffused and faint Æ TES detector
I
∝ √BKG Æ satellite orbit!!
min
Branchini E. et al, ApJ.697:328-344,2009
Zappacosta et al., ApJ 753 137, 2012
Planck: collaboration , Ade P. et al, A&A, no. aa20194-12 c ESO 2012 November 19, 2012
First clusters
• Extensive simulations/design and TES AC detector by Italian consortium by
GEANT4
F(5”)=10-13 c.g.s
x10
x6
Fe Kα
With the reduced background
‐Fe Kα
‐Lower errors: σT/T = 3.6%; σZ/Z = 10%
Cluster at the formation epoch
(z=2)
F=10-15 erg/cm2/s,
A=0.2 arcmin2, kT=2.0 keV,
Abundance 0.3, area=1m2,f/l=12m
January 24, 2014
7
The microcalorimeter does not distinguish the energy
deposition of a photon from the energy deposition of a particle.
p
Cryostat
X-IFU
CryoAC
X-IFU
Sviluppo dei TES per Raggi-X per Astrofisica in Italia
Coordinamento (PI)
Test e caratterizzazione dei prototipi
INAF/IAPS Roma
Realizzazione dei sensori
Sviluppo dell’elettronica
INFN-Università di
Genova
TAS (ex Laben) Milano
CNR/IFN Roma
Co-PI per la realizzazione dello strumento X-IFU per
ATHENA+ insieme a
IRAP (Francia), SRON(Olanda)
How is energy measured?
Direct detection:
Equilibrium: The energy is deposited in an isolated thermal mass and the resulting increase in temperature
is measured. At the time of the measurement, all of the deposited energy has become heat and the sensor is
in thermal equilibrium. The ultimate energy resolution is determined by how well one can measure this
change in temperature against a background of thermodynamically unavoidable temperature fluctuations.
THIS IS CALORIMETRY.
Eγ = hν
From thermodynamics, at the thermal equilibrium,
C, T0
Eγ ~ ΔQ = C⋅ΔT
Æ ΔT ~ Eγ / C
THIS IS CRYOGENIC
MICRO-CALORIMETRY
the total content energy is: ET ~ C⋅T0~NKT0 Æ N ~ C/K
Energy of the bkg fluctuations σ(ET) ~ √N⋅KT0 ~ (KT2C)1/2
So, in microcalorimetry you compare σ(ET) with Eγ
To decrease σ(ET) ~ (KT2C)1/2
Low temperature
Æ Cryogenic detector
Low heat capacity detector
Æ micro detector
TES microcalorimeter: working Principle
…used from Microwave to soft-Gamma ray domain...
α=
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 Æ Absorber temperature change Æ Change in TESresistance. Since the TES is Voltage polarised Æ Change in current
Weak currents (also < μA), low TES Resistance (~ 0.1 Ohm) Æ a special lownoise current amplifier is required Æ SQUID Amp. (Superconducting
Quantum Interference Device Amplifier)
Electro-Thermal Feedback – Energy Bandwidth – Energy Resolution
C
τ th =
G
τ ETF =
α ⎡
τ th
1+ L
Tb << TTES ⇒ τ ETF ≅
⎛ T ⎞
L = ⋅ ⎢1 − ⎜⎜ b ⎟⎟
n ⎢ ⎝ TTES ⎠
⎣
n
⎤
⎥
⎥⎦
τ th
<< τ th
1+ α n
The Joule heating produced by Voltage bias
PJ = V2/R:
if T↑ Æ R↑ Æ PJ↓ Æ R↓
⇒ Electro-Thermal stability
Moreover: strong reduction of the decay time
constant Æ fast signals Æ high count rate
(bright sources or big area optics)
En. Bandwidth EMAX
Attenuation of thermal bath
temperature fluctuations
CT
=
0.63 ⋅ α
En. Resolution ΔEFWHM ≅ 2.35 ⋅
1
α
⋅ kT 2C ≅ kTEMAX
High En. BW Æ High C, Low alfa (wide transition)
High En. Res. Æ low T Æ cryogenic detector
Æ low C Æ high alfa (narrow transition)
Trade off is necessary to reach the wanted
performances
Tb/TTES
Curva Transizione TES
Le nostre attivita’ in laboratorio all’INAF/IAPS Roma:
Fisica atomica, Struttura della Materia, Elettronica,
Calcolo Numerico
ELETTRONICA CRIOGENICA
TES: Criostato dry della Vericold inserito
in una Farady Cage: Pulse tube
cooler(3K); ADR a doppio stadio (35 mK)
Pulse tube cooler (2.3 K)
Mu-metal
shield
In questi anni ….
…misure di transizione…
…analisi degli impulsi,
componenti termica ed atermica…
…misure di rumore Johnson…
Le attività proposte: misure e loro analisi dati
Caratterizzazione di prototipi a
singolo pixel di microcalorimetri
TES (X-ray) per rivelatori di
anticoincidenza (I-V, transizioni,
spettri, noise….)
Studio delle applicazioni
astrofisiche e cosmologiche
(necessita’ di adottare TES)
Riferimenti:
INAF/IAPS Roma Via del Fosso del Cavaliere, 100 (Tor Vergata, autobus 509 da Anagnina)
[email protected]
[email protected]

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