Metallic Magnetic Calorimeters for High-Resolution X-ray Spectroscopy
D. Hengstler, C. Pies, S. Schäfer, S. Kempf, M. Krantz, L. Gamer, J. Geist, A. Pabinger, E. Pavlov, P. Ranitzsch, M. Wegner, V. Wißdorf, T. Wolf,L. Gastaldo, A. Fleischmann,C. Enss
Kirchhoff-Institute for PhysicsHeidelberg University
1 x 8 pixel array for X-rays up to 20 keV250 m
250 m
5 m
X-ray absorber:Electrodeposited Au
Stems:Electrodeposited Au
Temperature sensor:Co-sputtered Au:Er300 ppm
Superconducting pickup coil:Sputtered Nb
SQUID magnetometer
1 x 8 pixel array for X-rays up to 20 keV
@ 0 keV: DEFWHM=3.0 eV
55Mn characterization measurementsCo
unts
/ 0.
3 eV
Energy [keV]Co
unts
/ 0.
3 eV
Energy [keV]
Baseline
Compared to expected energy resolution DEFWHM=2.6 eV slightly degraded due to untriggered small pulses
@ 6 keV: DEFWHM=3.4 eV
55Mn characterization measurementsM
easu
red
ener
gy [k
eV]
Energy [keV]
Diffe
renc
e [k
eV]
Non-linearity ~ 0.5%• Quadratic deviation• As expected from
theory
Flux
cha
nge
[Φ0]
Time [s]
Rise time ~80 ns• Given by Korringa
relation of Er in Au
Cross talk
Only relevant if DEFWHM < 1eV
Cross talkx 10-
4
X-ray spectroscopy at an EBIT at the MPIK*
detector
ADR EBIT
* Max-Planck-Institute for Nuclear Physics, Heidelberg
Superconducting Nb grid
Magnetic Shielding
7 mm
Nb cup attached to 4K plattform
• Microfabricated• Spacing 100 m• Width 5 m• Thickness 3 m• Trancparency ~ 90%
Magnetic Shielding
Al cup attached to detector plattform
Mechanical noise supressed
Without Al shield
With Al shield
X-ray spectroscopy at an EBIT at the MPIK
Transitions in Sc-like (W53+) ... Ni-like (W46+) tungsten
electron energy (eV)
phot
on e
nerg
y (e
V)
photon energy (eV)
photon energy (eV)
S. Georgi, Max-Planck-Institute for Nuclear Physics, Heidelberg, 2013
Detecting 60 keV
@ 0 keV: DEFWHM= 1.5 eVNon-linearity: 3.3 % @ 60 keV
6.4 0
1 x 8 pixel array for X-rays up to 200 keV
SQUID
@ 0..10 keV: DEFWHM=40 eV
2000 m
500 m140
m
In perfect agreement with expected resolution
Introduce stems as thermal bottle neck
1 x 8 pixel array for X-rays up to 200 keV
DEFWHM=60 eV
SQUID
Au:Er sensor
Au absorber
1st Nb layer
Massive absorber on 7 m thick stems
Measured Simulated (FEMM)
@ 60 keV: DEFWHM=60 eV Degradation due to position
dependent pulse shape
Towards a 2d-array
7 mm
1 mm
2 mm
8 mm
Planned detector geometries
Detector will be mounted on the side arm of a dry dilution fridge
Summary
Design for low-energy X-rays• DEFWHM = 3.4 eV @ 6 keV• Magnetic shielding with microstructured Nb grid• Non-linearity 3.3% @ 60 keV
Design for high-energy X-rays• DEFWHM = 40 eV @ 0..10 keV• DEFWHM = 60 eV @ 60 keV• Introduce stems to prevent position dependent
pulse shape
Towards a 2d array• Different geometries• Covering a large energy range• Mounted on a 40 cm long side arm
Applications maXs: X-ray spectroscopy
atomic physics astronomy
X-ray imaging large MMC arrays microwave SQUID multiplexing
Detection of molecular fragments
Radiation standards for metrology
Neutrino mass experiments β decay of 187Re (MARE) EC of 163Ho β β decay of 100Mo (AMoRE)
U91+
Advantages of MMCs High energy resolution Large energy bandwidth Quantum efficiency up to 100% Excellent linearity Fast signal rise time
maXs (Micro-Calorimeter Arrays for High Resolution X-Ray Spectroscopy)
Gas-Jet Target
(U Frankfurt)Beam of decelleratedHighly Charged Ions (HITRAP, GSI/FAIR)
X-Ray Lens for soft x-rays (U Jena)10
keV
100 keV
e.g. at Gas-Jet-Target behind HITRAP at GSI/FAIR
2d detector array
Towards a 2d-array
For X-rays up to 100 keV8 x 8 pixel array
Absorber volume• 500 x 500 x 30 µm3 4
mm
Future geometry
Stopping power• 100 % @ 10 keV• 53 % @ 40 keV• 26 % @ 100 keVExpected energy resolution• DEFWHM=6 eV @ 20mK
7 mm
48 large area absorbers• For high-energy X-rays• 1 x 1 mm2 detection area16 high-resolution absorbers• For low-energy X-rays• In center of the array 1
mm
Towards a 2d-array
For X-rays up to 100 keV8 x 8 pixel array
Absorber volume• 500 x 500 x 15 µm3 4
mm
Alternative geometrie
Stopping power• 97 % @ 10 keV• 32 % @ 40 keV• 14 % @ 100 keVExpected energy resolution• DEFWHM=10 eV
7 mm
49 large area absorbers• For high-energy X-rays
16 high-resolution absorbers• In center of the array• For low-energy X-rays
1 mm
Detector will be placed on the side arm of a dry dillution fridge