Kinetic Inductance Detectors (KIDs) provide a promising solution to the problem of producing large format arrays of ultra sensitive detectors for astronomy. Traditionally KIDs have been constructed from superconducting quarter-wave resonant elements capacitively coupled to a co-planar feed line [1]. Photon detection is achieved by measuring the change in quasi-particle density caused by the splitting of Cooper pairs in the superconducting resonant element. This change in quasi-particle density alters the kinetic inductance, and hence the resonant frequency of the resonant element. This arrangement requires the quasi-particles generated by photon absorption to be concentrated at positions of high current density in the resonator. This is usually achieved through antenna coupling or quasi-particle trapping. For these detectors to work at wavelengths shorter than around 500 μm where antenna coupling can introduce a significant loss of efficiency, then a direct absorption method needs to be considered. One solution to this problem is the Lumped Element KID (LEKID), which shows no current variation along its length and can be arranged into a photon absorbing area coupled to free space and therefore requiring no antennas or quasi-particle trapping. This paper outlines the relevant microwave theory of a LEKID, along with theoretical and measured performance for these devices.

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Lumped Element Kinetic Inductance Detectors

The photon energy dependence of the mean energy W required to produce an electron-hole pair in silicon for photons with energies between 50 and 1500 eV was determined from the spectral responsivity of selected silicon photodiodes. The spectral responsivity was measured with a relative uncertainty of less than 0.3% using monochromatized synchrotron radiation whose radiant power was measured with a cryogenic electrical substitution radiometer. In order to deduce W from the spectral responsivity of photodiodes with a relative uncertainty of about 1%, a method for the calculation of photon and electron escape losses from silicon photodiodes was developed and the model for the charge carrier recombination losses was improved. In contrast to recent theoretical and experimental results, a constant value W=(3.66±0.03) eV was obtained in the photon energy range from 50 to 1500 eV. The present experimental results are confirmed by calculation of the pair creation energy in silicon from data from the literature for ...

http://www.ba.infn.it/~mazziot/JAP02926.pdf

Mean energy required to produce an electron-hole pair in silicon for photons of energies between 50 and 1500 eV

A new type of microstructure device for a gas radiation detector is proposed. This microstructure, the microhole and strip plate structure, merges the structures of a gas electron multiplier and a microstrip plate in one single plate. This design allows two-multiplication stages and a separation of the sensitive and the detection regions, with full optical positive feedback suppression. Simulations for gas gain and electron transparency of the microstructure are presented. Different applications are discussed.

A proposed new microstructure for gas radiation detectors: The microhole and strip plate

This study provides quantitative insight into the formation of vortex breakdown and the onset of global instability
in a turbulent swirling jet. A water jet is guided through a rotating honeycomb that imparts the rotational motion,
passed through a contraction, and discharged into a large water tank. The flow states evolving at increasing swirl are
mapped out via time-resolved particle image velocimetry. The experimental results scale properly with the swirl
number based on the axial momentum flux when the commonly used boundary-layer approximations are omitted.
The instantaneous velocity field reveals that vortex breakdown occurs intermittently at a wide range of swirl
numbers before it appears in the mean flow. At this intermittent state, the evolving breakdown bubble oscillates
heavily between two streamwise locations where the vortex core is subcritical. Upon further increasing the swirl, the
breakdown oscillations decay and a region of reversed flow appears in the mean flowfield. The formation of this socalled
axisymmetric breakdown state is accompanied by a supercritical-to-subcritical transition of the inflowing
vortex core. The reversed flow region is found to grow linearly with increasing swirl until the flow undergoes a
supercritical Hopf bifurcation to a global single-helical mode, and vortex breakdown adopts a spiral shape. The
global mode shape is extracted from the particle image velocimetry snapshots by means of proper orthogonal
decomposition and Fourier analysis. The present experiment reveals that, at gradually increasing swirl, the jet first
transitions to an axisymmetric breakdown state that remains globally stable until a critical swirl number is exceeded.
This sequence of flow states agrees well with the transient formation of vortex breakdown observed in laminar flows.

Formation of Turbulent Vortex Breakdown: Intermittency, Criticality, and Global Instability

Ionizing radiation can be detected by the measurement of the charge carriers produced in a detector. The improved semiconductor technology now allows detectors operating near the physical limits of the detector materials to be designed. The mean energy required for producing an electron–hole pair, W, is a material property of the semiconductor. Here, the determination of W from the spectral responsivity of photodiodes is demonstrated. Using spectrally dispersed synchrotron radiation, different types of semiconductor photodiodes have been examined in the UV-, VUV-, and soft X-ray spectral range. Their spectral responsivity was determined with relative uncertainties between 0.4% and 1% using a cryogenic electrical-substitution radiometer as primary detector standard. Results are presented for silicon n-on-p junction photodiodes and for GaAsP/Au Schottky diodes at room temperature. The investigations for silicon covered the complete spectral range from 3 to 1500 eV, yielding a constant value W=(3.66±0.03) eV for photon energies above 50 eV, a maximum value of W=4.4 eV at photon energies around 6 eV, and a linear relation W=hν (one electron per photon) for photon energies below 4 eV. For GaAsP, we obtained a constant value of W=4.58 eV in the photon energy range from 150 to 1500 eV, with a relative uncertainty of 1–3%, depending on the photon energy.

Determination of the electron–hole pair creation energy for semiconductors from the spectral responsivity of photodiodes

Response of niobium-based superconducting tunnel junctions in the soft-x-ray region 0.15-6.5 keV.

https://depositonce.tu-berlin.de/bitstream/11303/8039/2/1-s2.0-S0955598616300875-main.pdf

Simulation-based determination of systematic errors of flow meters due to uncertain inflow conditions

https://cyberleninka.org/article/n/1036641.pdf

Calibration of an ultrasonic flow meter for hot water

The Danish Space Research Institute will provide a set of two low energy proportional counters (LEPC) and two high energy proportional counters (HEPC) for the Russian SPECTRUM-X-Gamma mission. The detectors are based upon the technology of the microstrip gas chamber (MSGC).

HEPC and LEPC use a XeCH4 mixture as the counter gas. The response function as well as the pulse height-energy relation for a XeCH4 filled MSGC were investigated with monochromatized synchrotron radiation of the BESSY double crystal monochromator.

The detector response functions were recorded at ∼100 selected photon energies in the range from 1.8 to 5.9 keV. The response functions were measured with photon energy steps of 5 eV around the Xe L subshells.

The average pulse height versus photon energy relation shows clear jumps at the L edges of 55 eV, 25.6 eV and 153. eV at the L3, L2 and L1 shell, respectively. The widths of the pulse height distributions indicate an increase of the Fano factor for Xe at the L absorption edges. These results are in good agreement with earlier predictions.

Detailed analysis of the shape of the photopeaks as well as of the tail and escape contributions will also be presented.

The response functions of the HEPC/LEPC detector system measured at the Xe L edge region

https://depositonce.tu-berlin.de/bitstream/11303/8033/2/1-s2.0-S0955598615300200-main.pdf

Thomas Lederer

Papers

Response of niobium-based superconducting tunnel junctions in the soft-x-ray region 0.15-6.5 keV.

Simulation-based determination of systematic errors of flow meters due to uncertain inflow conditions

Calibration of an ultrasonic flow meter for hot water

The response functions of the HEPC/LEPC detector system measured at the Xe L edge region

Uncertainty evaluation for velocity–area methods