MYTHEN: Microstrip sYstem for Time rEsolved experimeNts

MYTHEN is a 1D detector working in single-photon counting mode and meeting the high standards of synchrotron radiation experiments. It features low noise, high dynamic range, and excellent spatial resolution. Additionally, its numerous independent channels enable parallel data acquisition and facilitate time-resolved measurements at frame rates of up to 1 kHz, making it ideal for a wide range of applications in photon science.

The MYTHEN detector features a modular design that allows for the construction of larger systems to enhance area coverage. Each module consists of 1280 independent channels operating in parallel in single-photon counting mode, connected to strips of a silicon sensor. The detector achieves a spatial resolution of 50 μm, given by the strip pitch, with a sensor thickness of 320 μm and strip length of 8 mm. As a single-photon counting detector, MYTHEN offers virtually noiseless operation with a dynamic range of up to 24 bits, enabling the detection of low-energy photons down to 5 keV and high counting rates of up to 1 MHz/channel. It supports frame rates of up to 1 kHz with an inter-frame dead time of 0.07-0.25 ms and allows acquisition times down to 100 ns and synchronization with external trigger signals. A small onboard memory can store multiple frames in real time, enhancing data acquisition flexibility. Tailoring to different application requirements, custom sensors with various geometrical characteristics or materials are available.

After 12 years of operation at the Material Science beamline, MYTHEN was upgraded to MYTHEN III, featuring a readout chip with reduced noise and threshold dispersion for improved low-energy operation and fluorescence discrimination. The new design supports a count rate above 1 MHz per channel and incorporates three independent trimmable comparators per channel with gateable counters for advanced experimental capabilities such as multiple time slots, energy binning, or pileup-tracking to increase the count rate. With an upgraded readout and mechanical system, MYTHEN III can achieve a frame rate exceeding 1 MHz (when using 1 bit for a single counter and several kHz with all 3 counters, 24 bit dynamic range) and enables single-shot diffraction pattern acquisition. It was installed at the MS beamline in early 2020.

MYTHEN was originally designed for powder diffraction measurments at the Material Science Beamline of the SLS. The system installed at the beamline is capable of acquiring 120° (in 2θ) diffraction patterns with sub-sec time resolution. Overall it consists in more than 40'000 channel acquiring independently in parallel and is optimal for time-resolved and dose-critical measurements.

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.