LARGE AREA TRANSITION-EDGE SENSOR
ARRAY FOR PARTICLE INDUCED X-RAY
EMISSION SPECTROSCOPY
M Palosaari 1 , K Kinnunen 1 , I Maasilta 1 , C Reintsema 2 , D Schmidt 2 , J Fowler 2 , R
Doriese 2 , J Ullom 2 , M Käyhkö 1 , J Julin 1 , Mikko Laitinen 1 , T Sajavaara 1
1 Department of Physics, University of Jyväskylä, P.O. Box 35, Jyväskylä 40014, Finland
2 National Institute of Standards and Technology, Boulder CO 80305, United States email: mikko.i.laitinen@jyu.fi

Superconducting 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
Normal state
Superconducting state
Typical transition of a TES

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 pixel
TES array made in VTT, Finland.
In typical TES array, all pixels different
-> automated calibration essential

Details inside the instrument
~15 mm
~300 m m

Jyväskylä TES specifications


160 pixels from NIST, upgradable to 256 (from VTT)
Total area with 160 pixels ~16 mm 2


Single pixel count rate limited to <20 Hz, typical value 10 Hz
2 m m thick Bi absorber with Mo/Cu superconducting juction

Detection efficiencies with 100 um of Be:
80 % at 5 keV,
20 % at 10 keV,
5 % at 30 keV

Low energies limited by
MeV particle absorber, probably not needed

PIXETES results from Jyväskylä
Roughly one year ago: 12 pixels
Mn Kα from Fe-55 source
Best pixel
Instrumental resolution for the best pixel with 55 Fe source was 3.06 eV

PIXETES results from Jyväskylä
Now: 160 pixels…
• 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 eV for combined 40 pixels,
Improvement seen by better data analysis

PIXETES 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

PIXETES results from Jyväskylä
SRM-611, trace elements in glass

PIXETES results from Jyväskylä
SRM-611, trace elements in glass
Differences between pixels which are not only statistics

PIXETES results from Jyväskylä
SRM-1157, speciality tool steel
No Si escape peak
Bi escape peaks
Single measurement, wide energy range

PIXETES results from Jyväskylä
SRM-1157, speciality tool steel
V, Cr, Mn, Fe separated

In the Near Future

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 ???

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 mm 2
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No liquid He needed for ADR cryo cooler

Largish instrument: ~5 cm sample-to-detector
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Data handling and analysis: automation necessary
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Is the chemical information achievable, after all ?

Acknowledgements

38. July, 2016, in Jyväskylä, Finland

Single pixel shows Si peaks nicely but without good calibration, sum spectrum useless
No/bad calibration regime
Sample: SRM-611 good calibration

Raw pulse height data where sample was changed.
Sample 1 Sample 2
Substrate was Si for both samples
Measurement time/duration

Making selection to single (example) emission line
• Before liner fit
Straight line to guide the eye

• After linear fit
Si
Straight line to guide the eye
Si

55
Mn Kα from Fe55 source same pixel
What is the origin of the hump?

Detector performance: PIXE Mn vs. 55 Fe source
Instrumental resolution for the best pixel with 55 Fe 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

Traditional PIXE applications
– Archaeology
– Geology
– Filters in industry
– Old paintings
With better detectors one could see the chemical environment of the sample.
Rev. Sci. Instrum. 78, 073105 (2007)
J. Hasegawa et. al

Impurities in the Cu sample resolved better with TES detector

55
Mn Kα from Fe55 source same pixel
FWHM broadens less than 1eV.

Example: Thin film with high mass element



Atomic layer deposited Ru film on HF cleaned Si
Scattered beam, 35 Cl, used for Ru deph profile
Monte Carlo simulations needed for getting reliable values for light impurities at the middle of the film
Si
Ru
SiO
2
Poor E resolution
Low energy heavy ion ERDA – See posters!




: Diamond-like carbon films
2.3 µm thick diamond-like-carbon film on Si, measured with 9 MeV 35 Cl
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

2
3



Atomic layer deposited Al
2
O
3 film on silicon (Prof. Ritala, U. of Helsinki)
Density of 2.9 g/cm 3 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.%

x


TOF-ERDA results from sputter deposited 10 nm thick CN x hard coating on
Si. Measured with 6 MeV 35 Cl beam and extreme glancing angle of 3 °
A density of 2.0 g/cm 3 was used in converting areal densities to nm


13.6 MeV 63 Cu 7+ CaPO (hydroxyapatite)



Thin (~100 nm) SiN window
Electrons for T2 timing signal emitted from the membrane

Future improvements: Gas ionization detector
TOFE results from ETH Zürich
Incident ion 12 MeV 127 I 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


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
Recoil ranges in isobutane
10.2 MeV 79 Br 8.5 MeV 35 Cl
Gas ionization detector develoment – See posters!