
MYTHEN: Microstrip sYstem for Time rEsolved experimeNts
Detector description
The X-rays are absorbed in the silicon sensor, and the charge generated is collected at the electrodes and read out by a custom developed frontend electronics. The strip pitch, giving the spatial resolution of the detector, is 50 μm, the sensor thickness is 320 μm and the strip length is 8 mm. Custom sensors with different geometrical characteristics or materials different than sislicon can also be used to match the application requirements.
Thanks to the single photon counting capability the detector is virtually noiseless and has a dynamic range of up to 24 bits. The fluctuation on the number of detected photons is purely Poisson-like and thus the data quality is maximized also with low statistics. The low noise of the front-end electronics allows the detection of photons of energy down to 5 keV, while the short shaping time of the analog signal permits counting rates of up to 1 MHz/channel. The channels are read out in parallel with an inter-frame dead time of 0.07-0.25 ms. The maximum frame rate of the whole detector is limited by the data transfer rate which can be up to 1 kHz for a single module. Acquisition times down to 100 ns are possible and can be synchronized to users’ experiments using external signals. A small on-board memory can store 4 to 32 frames (depending on the dynamic range) in real time.
MYTHEN III
After 12 year of operation at the Material Science beamline, MYTHEN is going to be upgraded with a new version.
The new MYTHEN III readout chip features lower noise and threshold dispersion than its predecessor which will allow operation at lower energies and facilitate the selection of the energy also in presence of fluorescence. the shaping time is also much shorter, allowing a count rate capability higher than 1 MHz per channel, which can also be improved by pileup-tracking.
Moreover, each channel contains three independent trimmable comparators with gateable counters. This allows pump-probe experiments with multiple time slots, energy binning or pileup-tracking to increase the count rate capability.
Together with the new chip, the readout system will be upgraded, providing a frame rate which can be higher than 1 MHz when using a 1 bit for a single counter (and is still several kHz wit all 3 counters, 24 bit dynamic range). The readout is fully parallel therefore the frame rate does not slow down for increasing detector size.
The detector will also have a new mechanics which will allow the acquisition of a diffraction pattern in a single shot, without the need to move the detector to cover the gaps between the modules.
The new MYTHEN III detector is under commissioning and will be installed at the MS beamline in the first half of 2020.
Applications
Thanks to its outstanding performance and the calibration procedure developed at the SLS, the data quality is now comparable to that of traditional high-resolution detectors, with the further advantage of very fast data acquisition or, equivalently, very high counting statistics in acquisition times of the order of tens of seconds. MYTHEN is therefore also ideal for analyses of pair distribution functions (PDFs).
In 2012 the MYTHEN Detector has been upgraded by adding a second detector capable of detecting the hard X-rays transmitted by the first one. The use of thicker silicon sensors further increases the efficiency of the system, as shown in the pictures below.
MYTHEN modules are used also for several other type of experiments including energy dispersive spectrometers, beam position monitors and medical imaging.
Examples
The data quality is outstanding in terms of FWHM resolution, peak profile shape, counting efficiency and linearity.
Thanks to the short acquisition times, the radiation damaged is reduced and can be monitored during the measurement.
Publications
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Andrä M, Barten R, Bergamaschi A, Brückner M, Casati N, Cervellino A, et al.
Towards MYTHEN III - prototype characterisation of MYTHEN III.0.2
Journal of Instrumentation. 2019; 14(11): C11028 (8 pp.). https://doi.org/10.1088/1748-0221/14/11/C11028
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Osaka K, Yokozawa Y, Torizuka Y, Yamada Y, Manota M, Harada N, et al.
Versatile high-throughput diffractometer for industrial use at BL19B2 in SPring-8
In: Gwo S, Huang D-J, Wei D-H, eds. Proceedings of the 13th international conference on synchroton radiation instrumentation - SRI2018. Vol. 2054. AIP conference proceedings. sine loco: AIP Publishing; 2019:050008 (5 pp.). https://doi.org/10.1063/1.5084626
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Andrä M, Dinapoli R, Bergamaschi A, Barten R, Brückner M, Chiriotti Alvarez S, et al.
Towards MYTHEN 3: characterization of prototype chips
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2018; 936: 383-385. https://doi.org/10.1016/j.nima.2018.11.026
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Ruat M, Andrä M, Bergamaschi A, Barten R, Brückner M, Dinapoli R, et al.
Photon counting microstrip X-ray detectors with GaAs sensors
Journal of Instrumentation. 2018; 13(1): C01046 (9 pp.). https://doi.org/10.1088/1748-0221/13/01/C01046
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Elbracht-Leong S, Bergamaschi A, Greiffenberg D, Peake D, Rassool R, Schmitt B, et al.
Characterisation of an electron collecting CdTe strip sensor using the MYTHEN readout chip
Journal of Instrumentation. 2015; 10(1): C01024 (10 pp.). https://doi.org/10.1088/1748-0221/10/01/C01024
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Grässlin J, McCusker LB, Baerlocher C, Gozzo F, Schmitt B, Lutterotti L
Advances in exploiting preferred orientation in the structure analysis of polycrystalline materials
Journal of Applied Crystallography. 2013; 46(1): 173-180. https://doi.org/10.1107/S0021889812045943
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Bergamaschi A, Dinapoli R, Greiffenberg D, Henrich B, Johnson I, Mozzanica A, et al.
Time-over-threshold readout to enhance the high flux capabilities of single-photon-counting detectors
Journal of Synchrotron Radiation. 2011; 18(6): 923-929. https://doi.org/10.1107/S0909049511034480
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Lopez FC, Rigon L, Longo R, Arfelli F, Bergamaschi A, Chen RC, et al.
Development of a fast read-out system of a single photon counting detector for mammography with synchrotron radiation
Journal of Instrumentation. 2011; 6(12): C12031. https://doi.org/10.1088/1748-0221/6/12/C12031
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Bergamaschi A, Cervellino A, Dinapoli R, Gozzo F, Henrich B, Johnson I, et al.
The MYTHEN detector for X-ray powder diffraction experiments at the Swiss Light Source
Journal of Synchrotron Radiation. 2010; 17(5): 653-668. https://doi.org/10.1107/S0909049510026051
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Fadenberger K, Gunduz IE, Tsotsos C, Kokonou M, Gravani S, Brandstetter S, et al.
In situ observation of rapid reactions in nanoscale Ni-Al multilayer foils using synchrotron radiation
Applied Physics Letters. 2010; 97(14): 144101 (3 pp.). https://doi.org/10.1063/1.3485673
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Gozzo F, Cervellino A, Leoni M, Scardi P, Bergamaschi A, Schmitt B
Instrumental profile of MYTHEN detector in Debye-Scherrer geometry
Zeitschrift für Kristallographie: Crystalline Materials. 2010; 225(12): 616-624. https://doi.org/10.1524/zkri.2010.1345
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Bergamaschi A, Cervellino A, Dinapoli R, Gozzo F, Henrich B, Johnson I, et al.
Photon counting microstrip detector for time resolved powder diffraction experiments
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2009; 604(1-2): 136-139. https://doi.org/10.1016/j.nima.2009.01.092
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Mozzanica A, Bergamaschi A, Dinapoli R, Gozzo F, Henrich B, Kraft P, et al.
MythenII: a 128 channel single photon counting readout chip
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2009; 607(1): 250-252. https://doi.org/10.1016/j.nima.2009.03.166
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Rigon L, Arfelli F, Astolfo A, Bergamaschi A, Dreossi D, Longo R, et al.
A single-photon counting "edge-on" silicon detector for synchrotron radiation mammography
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2009; 608(1 SUPPL.): S62-S65. https://doi.org/10.1016/j.nima.2009.05.036
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Bergamaschi A, Broennimann C, Dinapoli R, Eikenberry E, Gozzo F, Henrich B, et al.
Performance of a single photon counting microstrip detector for strip pitches down to 10 μm
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2008; 591(1): 163-166. https://doi.org/10.1016/j.nima.2008.03.048
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Dreossi D, Bergamaschi A, Schmitt B, Vallazza E, Arfelli F, Longo R, et al.
Clinical mammography at the SYRMEP beam line: Toward the digital detection system
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2007; 576(1): 160-163. https://doi.org/10.1016/j.nima.2007.01.145
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Rosciano F, Holzapfel M, Kaiser H, Scheifele W, Ruch P, Hahn M, et al.
A multi-sample automatic system for in situ electrochemical X-ray diffraction synchrotron measurements
Journal of Synchrotron Radiation. 2007; 14(6): 487-491. https://doi.org/10.1107/S0909049507039209
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Schmitt B, Brönnimann C, Eikenberry EF, Hülsen G, Toyokawa H, Horisberger R, et al.
Development of single photon counting detectors at the Swiss Light Source
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 2004; 518(1-2): 436-439. https://doi.org/10.1016/j.nima.2003.11.051
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