LARGE AREA TRANSITION-EDGE SENSOR ARRAY FOR PARTICLE INDUCED X-RAY
EMISSION SPECTROSCOPY
M Palosaari1, K Kinnunen1, I Maasilta1, C Reintsema2, D Schmidt2, J Fowler2, R Doriese2, J Ullom2, M Käyhkö1, J Julin1, Mikko Laitinen1, T Sajavaara1
1Department of Physics, University of Jyväskylä, P.O. Box 35, Jyväskylä 40014, Finland2National Institute of Standards and Technology, Boulder CO 80305, United States
email: [email protected]
INTRODUCTION to TESSuperconducting Transition-Edge Sensor
Transition-Edge Sensor (TES)
TES as a calorimeter– Measures the energy of incident radiation
Schematics of a calorimeter
Typical pulse from a calorimeter
TES Operation Operates between superconducting and normal state
Extremely sensitive R(T)
Excellent energy resolution
Wide energy range
Detects radiation,in our case X-rays
Particles also possible
Typical transition of a TES
Normal state
Superconducting state
tran
sitio
n ed
ge
TES basics TES thin film device is made of normal metal -
superconducting metal bilayer.
The absorber details depend on the desired energy range.
TESs are usually fabricated on thin SiN membranes to limit the thermal conductivity G.
Photograph of a 256 pixelTES array made in VTT, Finland.
In typical TES array, all pixels different-> automated calibration essential
PIXE-TES SETUP IN JYVÄSKYLÄ
PIXE-TES Setup in Jyväskylä
~300 m~15 mm
Details inside the instrument
Jyväskylä TES specifications 160 pixels from NIST, upgradable to 256 (from VTT)
Total area with 160 pixels ~16 mm2
Single pixel count rate limited to <20 Hz, typical value 10 Hz
2 m thick Bi absorber with Mo/Cu superconducting juction
Detection efficiencieswith 100 um of Be:80 % at 5 keV,20 % at 10 keV, 5 % at 30 keV
Low energies limited byMeV particle absorber,probably not needed
PIXE-TES MEASUREMENTSFrom a single pixel to many…
PIXE-TES results from Jyväskylä
Mn Kα from Fe-55 sourceBest pixel
Instrumental resolution for the best pixel with 55Fe source was 3.06 eV
Roughly one year ago: 12 pixels
PIXE-TES results from Jyväskylä
• But, Computer interface and I/O cards cannot handle all pixels simultaneously
• I/O card + PC update coming from NIST to finally secure the function of all 256 possible channels, simultaneously.
This month: data with Fe-55 source
Resolution around 5 eVfor combined 40 pixels,Improvement seen bybetter dataanalysis
Now: 160 pixels…
PIXE-TES results from Jyväskylä
SRM-611, trace elements in glass
All TES data shown was analyzed last week, 1 eV / bin
Analysis resolution for all of these plots ~10 eV
PIXE-TES results from Jyväskylä
SRM-611, trace elements in glass
PIXE-TES results from Jyväskylä
SRM-611, trace elements in glass
Differences between pixels which are not only statistics
PIXE-TES results from Jyväskylä
SRM-1157, speciality tool steel
No Si escape peak
Bi escape peaks
Single measurement, wide energy range
PIXE-TES results from Jyväskylä
SRM-1157, speciality tool steel
V, Cr, Mn, Fe separated
Read-out upgraded to full scale.
Modification of PIXE setup to be able to measure samples in atmosphere.
Study art samples in a project that just started
X-ray measurements with our own detector array fabricated by VTT.
Study the satellite peaks with different ions and energies. ->> Chemical information from wide energy/elemental range ???
In the Near Future
Conclusions Instrumental resolution of 3 eV demonstrated
Combined pixel resolution of ~5 eV looks realistic
Wide energy scale (“0” to tens of keV)
Reasonable count rates available (10 Hz/pixel, 256 pixels)
Active detector area about 16 mm2
No liquid He needed for ADR cryo cooler
Largish instrument: ~5 cm sample-to-detector
Data handling and analysis: automation necessary
Is the chemical information achievable, after all ?
Acknowledgements
t
3-8. July, 2016, in Jyväskylä, Finland
Pixel calibrationSingle pixel shows Si peaks nicely but without good calibration, sum spectrum useless
good calibration
No/bad calibration regime
Sample: SRM-611
TES-PIXE data calibrationRaw pulse height data
where sample was changed.
Measurement time/duration
Een
erg
y sc
ale
Substrate was Si for both samples
Sample 1 Sample 2
TES-PIXE dataMaking selection to single (example) emission line
•Before liner fit
Straight line to guide the eye
TES-PIXE data
Si
SiStraight line to guide the eye
• After linear fit
Nitride hits
Mn Kα from Fe55 sourcesame pixel
PIXE Mn vs. 55Fe
What is the origin of the hump?
Detector performance: PIXE Mn vs. 55Fe source
Instrumental resolution for the best pixel with 55Fe source was 3.06 eV.
For 2 MeV protons and Mn sample resolution was 4.20 eV.
M. Palosaari et. al J. Low Temp.DOI 201310.1007/s10909-013-1004-5
PIXE applications
Traditional PIXE applications– Archaeology– Geology– Filters in industry– Old paintings
Rev. Sci. Instrum. 78, 073105 (2007) J. Hasegawa et. al
With better detectorsone could see thechemical environmentof the sample.
TES vs. SDD
Impurities in the Cu sample resolved better with TES detector
Stainless steel example
Mn Kα from Fe55 sourcesame pixel
FWHM broadens less than 1eV.
PIXE Mn vs. 55Fe
TES vs. SDD
TES circuit diagram
Example: Thin film with high mass element Atomic layer deposited Ru film on HF cleaned Si
Scattered beam, 35Cl, used for Ru deph profile
Monte Carlo simulations needed for getting reliable values for light impurities at the middle of the film
Ru
Si
SiO2
Low energy heavy ion ERDA – See posters!
Poor E resolution
Example: Diamond-like carbon films 2.3 µm thick diamond-like-carbon film on Si, measured with 9 MeV 35Cl
All isotopes can be determined for light masses
Light elements can be well quantified (N content 0.05±0.02 at.%)
Low energy heavy ion ERDA
ALD 8.6 nm Al2O3/Si Atomic layer deposited Al2O3 film on silicon (Prof. Ritala, U. of Helsinki)
Density of 2.9 g/cm3 and thickness of 8.6 nm determined with XRR (Ritala)
Elemental concentrations in the film bulk as determined with TOF ERDA are O 60±3 at.%, Al 35±2 at.%, H 4±1 at.%. and C 0.5±0.2 at.%
10 nm CNx on silicon TOF-ERDA results from sputter deposited 10 nm thick CNx hard coating on
Si. Measured with 6 MeV 35Cl beam and extreme glancing angle of 3°
A density of 2.0 g/cm3 was used in converting areal densities to nm
Effect of stripper gas pressure
13.6 MeV 63Cu7+ CaPO (hydroxyapatite)
Gas ionization detector Thin (~100 nm) SiN
window
Electrons for T2 timing signal emitted from the membrane
Future improvements: Gas ionization detector
TOF-E results from ETH Zürich
Incident ion 12 MeV 127I and borosilicate glass target
Nucl. Instr. and Meth. B 248 (2006) 155-162 200 nm thick SiN membrane from Aalto
University, Finland, on 100 mm wafer
30 mm
Gas ionization detector to replace Si-energy detector Why try to fix a well working system?
Greatly improved energy resolution for low energy heavy ions → heavier masses can be resolved
Gas detector is 1D position sensitive by nature → possibility for kinematic correction and therefore larger solid angles possible
Gas detector does not suffer from ion bombardment
10.2 MeV 79Br 8.5 MeV 35Cl
Recoil ranges in isobutane
Gas ionization detector develoment – See posters!
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