17 results on '"Akamatsu, H."'
Search Results
2. Frequency shift algorithm: Application to a frequency-domain multiplexing readout of x-ray transition-edge sensor microcalorimeters.
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Vaccaro, D., Akamatsu, H., van der Kuur, J., van der Hulst, P., Nieuwenhuizen, A. C. T., van Winden, P., Gottardi, L., den Hartog, R., Bruijn, M. P., D'Andrea, M., Gao, J. R., den Herder, J. W. A., Hoogeveen, R. W. M., Jackson, B., van der Linden, A. J., Nagayoshi, K., Ravensberg, K., Ridder, M. L., Taralli, E., and de Wit, M.
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INTERMODULATION distortion , *MULTIPLEXING , *CALORIMETERS , *X-rays , *DETECTOR circuits - Abstract
In the frequency-domain multiplexing (FDM) scheme, transition-edge sensors (TESs) are individually coupled to superconducting LC filters and AC biased at MHz frequencies through a common readout line. To make efficient use of the available readout bandwidth and to minimize the effect of non-linearities, the LC resonators are usually designed to be on a regular grid. The lithographic processes, however, pose a limit on the accuracy of the effective filter resonance frequencies. Off-resonance bias carriers could be used to suppress the impact of intermodulation distortions, which, nonetheless, would significantly affect the effective bias circuit and the detector spectral performance. In this paper, we present a frequency shift algorithm (FSA) to allow off-resonance readout of TESs, while preserving the on-resonance bias circuit and spectral performance, demonstrating its application to the FDM readout of an x-ray TES microcalorimeter array. We discuss the benefits in terms of mitigation of the impact of intermodulation distortions at the cost of increased bias voltage and the scalability of the algorithm to multi-pixel FDM readout. We show that with FSA, in the multi-pixel and frequencies shifted on-grid, the line noises due to intermodulation distortion are placed away from the sensitive region in the TES response and the x-ray performance is consistent with the single-pixel, on-resonance level. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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3. Performance and uniformity of a kilo-pixel array of Ti/Au transition-edge sensor microcalorimeters.
- Author
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Taralli, E., D'Andrea, M., Gottardi, L., Nagayoshi, K., Ridder, M. L., de Wit, M., Vaccaro, D., Akamatsu, H., Bruijn, M. P., and Gao, J. R.
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CORRELATORS ,UNIFORMITY ,SOFT X rays ,CALORIMETERS ,CRITICAL temperature ,X-ray spectrometers ,DETECTORS ,PHOTON pairs - Abstract
Uniform large transition-edge sensor (TES) arrays are fundamental for the next generation of x-ray space observatories. These arrays are required to achieve an energy resolution ΔE < 3 eV full width at half maximum (FWHM) in the soft x-ray energy range. We are currently developing x-ray microcalorimeter arrays for use in the future laboratory and space-based x-ray astrophysics experiments and ground-based spectrometers. In this contribution, we report on the development and the characterization of a uniform 32 × 32 pixel array with 140 × 30 μm
2 Ti/Au TESs with the Au x-ray absorber. We report on extensive measurements on 60 pixels in order to show the uniformity of our large TES array. The averaged critical temperature is Tc = 89.5 ± 0.5 mK, and the variation across the array (∼1 cm) is less than 1.5 mK. We found a large region of detector's bias points between 20% and 40% of the normal-state resistance where the energy resolution is constantly lower than 3 eV. In particular, results show a summed x-ray spectral resolution ΔEFWHM = 2.50 ± 0.04 eV at a photon energy of 5.9 keV, measured in a single-pixel mode using a frequency domain multiplexing readout system developed at SRON/VTT at bias frequencies ranging from 1 MHz to 5 MHz. Moreover, we compare the logarithmic resistance sensitivity with respect to temperature and current (α and β, respectively) and their correlation with the detector's noise parameter M, showing a homogeneous behavior for all the measured pixels in the array. [ABSTRACT FROM AUTHOR]- Published
- 2021
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4. Characterization of High Aspect-Ratio TiAu TES X-ray Microcalorimeter Array Under AC Bias.
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Taralli, E., Gottardi, L., Nagayoshi, K., Ridder, M., Visser, S., Khosropanah, P., Akamatsu, H., van der Kuur, J., Bruijn, M., and Gao, J. R.
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X-rays ,PHYSICS experiments ,CALORIMETERS ,MATERIALS analysis - Abstract
We are developing X-ray microcalorimeters as a backup option for the baseline detectors in the X-IFU instrument on board the ATHENA space mission led by ESA and to be launched in the early 2030s. 5 × 5 mixed arrays with TiAu transition-edge sensor (TES), which have different high aspect ratios and thus high resistances, have been designed and fabricated to meet the energy resolution requirement of the X-IFU instrument. Such arrays can also be used to optimize the performance of the frequency domain multiplexing (FDM) readout and lead to the final steps for the fabrication of a large detector array. In this work, we present the experimental results from tens of the devices with an aspect ratio (length-to-width) ranging from 1-to-1 up to 6-to-1, measured in a single-pixel mode with a FDM readout system developed at SRON/VTT. We observed a nominal energy resolution of about 2.5 eV at 5.9 keV at bias frequencies ranging from 1 to 5 MHz. These detectors are proving to be the best TES microcalorimeters ever reported in Europe, intending to meet the requirements of the X-IFU instrument, but also those of other future challenging X-ray space missions, fundamental physics experiments, plasma characterization and material analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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5. Josephson Effects in Frequency-Domain Multiplexed TES Microcalorimeters and Bolometers.
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Gottardi, L., Smith, S. J., Kozorezov, A., Akamatsu, H., van der Kuur, J., Bandler, S. R., Bruijn, M. P., Chervenak, J. A., Gao, J. R., den Hartog, R. H., Jackson, B. D., Khosropanah, P., Miniussi, A., Nagayoshi, K., Ridder, M., Sadleir, J., Sakai, K., and Wakeham, N.
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SUPERCONDUCTIVITY ,SUPERCONDUCTORS ,BOLOMETERS ,CALORIMETERS ,TEMPERATURE measuring instruments - Abstract
Frequency-division multiplexing is the baseline read-out system for large arrays of superconducting transition-edge sensors (TES’s) under development for the X-ray and infrared instruments like X-IFU (Athena) and SAFARI, respectively. In this multiplexing scheme, the sensors are ac-biased at different frequencies from 1 to 5 MHz and operate as amplitude modulators. Weak superconductivity is responsible for the complex TES resistive transition, experimentally explored in great detail so far, both with dc- and ac-biased read-out schemes. In this paper, we will review the current status of our understanding of the physics of the TES’s and their interaction with the ac bias circuit. In particular, we will compare the behaviour of the TES nonlinear impedance, across the superconducting transition, for several detector families, namely: high-normal-resistance TiAu TES bolometers, low-normal-resistance MoAu TES microcalorimeters and high-normal-resistance TiAu TES microcalorimeters. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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6. Study of TES-Based Microcalorimeters of Different Size and Geometry Under AC Bias.
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Gottardi, L., Akamatsu, H., Van Der Kuur, J., Smith, S. J., Kozorezov, A., and Chervenak, J.
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CALORIMETERS , *SUPERCONDUCTORS , *CRYOELECTRONICS , *BOLOMETERS , *SUPERCONDUCTING transitions - Abstract
Frequency-division multiplexing (FDM) is the current baseline read-out system for the large array of superconducting transition edge sensors (TES's) under development for the X-ray instrument XIFU (Athena). In this multiplexing scheme the sensor operates as amplitude modulator of a MHz carrier. To achieve the best performance with these and similar instruments the detector physics and its interaction with the read-out circuit needs to be better understood. In particular we need an explanation for the dependence of the TES microcalorimeter nonlinear impedance on the bias point, because it directly affects the choice of the detector optimal working point. With the TES microcalorimeters fabricated at NASA-Goddard we observe current steps in the amplitude of the uncalibrated IV characteristics when the detectors are read-out in the frequency domain and are biased in the low-resistance part of the superconducting transition. In this paper, we report on the characterization under FDM of NASA-Goddard TES microcalorimeters under development for the XIFU instrument. We have measured several pixels with different size and geometry in the bias frequency range from 1 to 4 MHz and at different bath temperatures. The results will be discussed within the recently developed weak-link theoretical framework. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
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7. Thermal Load Minimization of the Frequency Domain Multiplexed Readout for the Athenar X-IFU Instrument.
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Van Der Kuur, J., Gottardi, L. G., Akamatsu, H. A., Van Leeuwen, B. J., Den Hartog, R., Kiviranta, M., and Jackson, B.
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ENERGY dissipation ,ASTROPHYSICS ,CALORIMETERS ,ENERGY consumption ,BANDWIDTHS - Abstract
The high sensitivity of cryogenic TES-based detectors opens new windows for astrophysical observations ranging from (far) infrared to X-rays. A number of operational and future space and ground-based instruments rely on cryogenic detectors to improve their performance with respect to the capabilities of earlier technologies. To reach the required sensitivities, base temperatures as low as 50 mK are necessary, and stringent requirements on magnetic shielding, microvibrations, and temperature stability are applicable. To minimize the heat load and complexity of the instruments, efficient multiplexing schemes and low-power amplifiers are needed. In addition, for space-based cryogenic instruments, mechanical launch loads and power consumption limitations constrain the available parameter space for engineering further. This paper discusses the system design considerations which are applicable to optimize the multiplex factor within the boundary conditions as set by the space craft for the X-IFU instrument on the Athena observatory. More specifically, the interplay between the science requirements such as pixel dynamic range, pixel speed, and cross talk, and the space craft requirements such as the power dissipation budget, and available bandwidth will be discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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8. Frequency domain multiplexing readout for large arrays of transition-edge sensors.
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Vaccaro, D., Akamatsu, H., Gottardi, L., van der Kuur, J., Nagayoshi, K., Taralli, E., de Wit, M., Bruijn, M.P., van der Linden, A.J., van Leeuwen, B.-J., van der Hulst, P., Ravensberg, K., de Vries, C.P., Kiviranta, M., Gao, J.-R., and den Herder, J.W.A.
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DIGITAL electronics , *SENSOR arrays , *SUPERCONDUCTING quantum interference devices , *MULTIPLEXING , *X-ray telescopes , *LOW noise amplifiers , *CALORIMETERS , *SQUIDS - Abstract
We report our most recent progress and demonstration of a frequency domain multiplexing (FDM) readout technology for transition-edge sensor (TES) arrays, both of which we have been developing in the framework of the X-IFU instrument on board the future Athena X-ray telescope. Using Ti/Au TES micro-calorimeters, high-Q LC filters and analog/digital electronics developed at SRON and low-noise two-stage SQUID amplifiers from VTT Finland, we demonstrated the feasibility of our FDM readout technology, with the simultaneous readout of 37 pixels with an energy resolution of 2.23 eV at an energy of 6 keV. We finally outline our plans for further scaling up and improving our technology in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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9. TES-Based X-ray Microcalorimeter Performances Under AC Bias and FDM for Athena.
- Author
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Akamatsu, H., Gottardi, L., Vries, C., Adams, J., Bandler, S., Bruijn, M., Chervenak, J., Eckart, M., Finkbeiner, F., Gao, J., Herder, J.-W., Hartog, R., Hoevers, H., Kelley, R., Khosropanah, P., Kilbourne, C., Kuur, J., Lee, S.-J., Linden, A., and Porter, F.
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CALORIMETERS , *ALTERNATING currents , *FREQUENCY division multiple access , *HIGH resolution imaging , *PIXELS , *MICROFABRICATION - Abstract
Athena is a European X-ray observatory, scheduled for launch in $$\sim $$ 2028. Athena will employ a high-resolution imaging spectrometer called X-ray integral field unit (X-IFU), consisting of an array of $$\sim $$ 4000 transition edge sensor (TES) microcalorimeter pixels. For the readout of X-IFU, we are developing frequency domain multiplexing, which is the baseline readout system. In this paper, we report on the performance of a TES X-ray calorimeter array fabricated at Goddard Space Flight Center (GSFC) at MHz frequencies for the baseline of X-IFU detector. During single-pixel AC bias characterization, we measured X-ray energy resolutions (at 6 keV) of about 2.9 eV at both 2.3 and 3.7 MHz. Furthermore, in the multiplexing mode, we measured X-ray energy resolutions of about 2.9 eV at 1.3 and 1.7 MHz. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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10. Impedance Measurement of a Gamma-Ray TES Calorimeter with a Bulk Sn Absorber.
- Author
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Akamatsu, H., Ishisaki, Y., Hoshino, A., Ezoe, Y., Ohashi, T., Takei, Y., Yamasaki, N. Y., Mitsuda, K., Oshima, T., and Tanaka, K.
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CALORIMETERS , *GAMMA rays , *PHONONS , *TEMPERATURE measuring instruments , *ELECTRIC impedance - Abstract
We performed complex impedance measurements with a Ti/Au-based gamma-ray TES calorimeter with a bulk Sn absorber. Excellent energy resolution of 38.4±0.9eV at 60 keV was observed. The impedance of the calorimeter can be well explained by a two-body thermal model. We investigated the behavior of the parameters of the calorimeter during the superconducting-to-normal transition. We confirmed that C and Ga are in good agreement with the predicted values. We performed a noise analysis and found several excess noise components, as well as internal thermal fluctuation noise (ITFN) term due to the thermal conductance between the Sn absorber and the Ti/Au TES. Dominanting the noise is an excess noise having a similar frequency dependence to the phonon noise and the ITFN noise. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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11. Impedance measurement and excess-noise behavior of a Ti/Au bilayer TES calorimeter.
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Akamatsu, H., Abe, Y., Ishikawa, K., Ishisaki, Y., Ezoe, Y., Ohashi, T., Takei, Y., Yamasaki, N. Y., Mitsuda, K., and Maeda, R.
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CALORIMETERS , *X-rays , *SPECTRUM analysis , *RADIATION , *RADIOGRAPHY - Abstract
To understand the so-called excess noise, we measured the complex impedance of a TES microcalorimeter, and derived the hernial sensitivity α, current sensitivity β, and heat capacity C. Making use of the obtained parameters, we found that the excess noise can be represented by two types of extra noise having similar spectra as Johnson and phonon noise. The contribution of the Johnson-like, usually expressed by the M factor, depended on α [formula] which is consistent with the behavior of the excess noise studied in other groups. Pursuing the better energy resolution, we suppressed the dominant noise components by introducing a Si collimator to irradiate X-rays only to the Au absorber, increasing the ADC resolution, and improving the temperature stability. So far, the energy resolution has been improved from 4.8 eV to 2.8 eV (FWHM). [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
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12. Performance test of Ti/Au bilayer TES microcalorimeter in combination with continuous ADR.
- Author
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Ishisaki, Y., Akamatsu, H., Hoshino, A., Numazawa, T., Kamiya, K., Fujimoto, R., Kojima, Y., Shinozaki, K., Mitsuda, K., and Shirron, P.
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CALORIMETERS , *REFRIGERATORS , *TRANSITION temperature , *MAGNETIC fields , *ELECTRIC equipment - Abstract
Performance test of a Ti/Au bilayer TES microcalorimeter has been made in combination with a continuous adiabatic demagnetization refrigerator (CADR). The CADR has four stages of ADR to produce continuous cooling by recycling them in dedicated order, and is cryogen-free utilizing a 4K-GM refrigerator. We installed a Ti/Au bilayer TES microcalorimeter and 420-series SQUID array to readout the X-ray signal on the 1st (coldest) stage of the CADR. We successfully operated the CADR at temperature of 120 mK in continuous mode more than 27 hr, however, FWHM energy resolution of the TES microcalorimeter was degraded to 45 eV at 6 keV, as compared to 10 eV when measured in a dilution refrigerator. This is mainly because the temperature stability was not good enough (about 0.6 mK) and the operation temperature was not sufficiently lower than the transition temperature Tc = 135mK of the TES. We operated the TES microcalorimeter at the operation temperature of 105 mK in one-shot mode and the resolution was improved to 30 eV. We also found that the operating point of the TES was affected by the magnetic field of the 3rd and 4th ADR recycle. More complete shielding of the magnetic field is essential for further improvement of the performance of the TES microcalorimeter. [ABSTRACT FROM AUTHOR]
- Published
- 2009
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13. Performance of TES X-ray Microcalorimeters with AC Bias Read-Out at MHz Frequencies.
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Akamatsu, H., Gottardi, L., Adams, J., Bandler, S., Bruijn, M., Chervenak, J., Eckart, M., Finkbeiner, F., Hartog, R., Hoevers, H., Kelley, R., Kilbourne, C., Kuur, J., Linden, A., Porter, F., Sadleir, J., Smith, S., and Kiviranta, M.
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PARTICLE detectors , *CRYOGENICS , *CALORIMETERS , *ALTERNATING currents , *HIGH resolution spectroscopy , *MAGNETIC fields , *ELECTRIC circuits - Abstract
At SRON we are developing Frequency Domain Multiplexing for the read-out of superconducting transition edge sensor microcalorimeters for future X-ray astrophysical missions. We will report on the performance of Goddard Space Flight Center pixels under AC bias in the MHz frequency range. Superconducting flux transformers are used to improve the impedance matching between the low ohmic TESs and the SQUID. We connected 5 pixels to the LC filters with resonant frequencies ranging between 1 and 5 MHz. For X-ray photons of 6 keV we measured a best X-ray energy resolution of 3.6 eV at 1.4 MHz, consistent with the integrated Noise Equivalent Power. In addition, we improved the electrical circuit by optimizing the coupling ratio of the impedance matching transformer. In addition, we improved electrical circuit for impedance matching; modified transformer coupling ratio. As a result, we got the integrated noise equivalent power resolution of 2.7 eV at 2.5 MHz. A characterization of the detector response as a function of the AC bias voltage, bias frequency and the applied magnetic field is presented. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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14. Radiation Tolerance Evaluation of the Ti/Au Bilayer TES Microcalorimeter.
- Author
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Ishisaki, Y., Enokijima, Y., Ezoe, Y., Ohashi, T., Akamatsu, H., Yamamoto, R., Takei, Y., Mitsuda, K., Yamasaki, N., and Yamada, S.
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RADIATION tolerance ,GOLD films ,BILAYERS (Solid state physics) ,PARTICLE detectors ,CRYOGENICS ,CALORIMETERS - Abstract
We have developed Ti/Au bilayer transition-edge sensor (TES) microcalorimeters for future X-ray astrophysical satellite missions such as DIOS. One possible concern on the space use of TES microcalorimeters is its radiation tolerance. We have evaluated the performance of a Ti/Au bilayer (30/40 nm thick) TES microcalorimeter with 1.5 $$\upmu $$ m thick Au absorber, before and after irradiation of 150 MeV proton beam with a total dose of 10 krad, corresponding to 10 years in the low Earth orbit. No significant changes on transition temperature, sensitivity, normal resistance, and critical current were observed. The energy resolution for 5.9 keV X-rays was 5.6 $$\pm $$ 0.3 eV (FWHM) after the irradiation, which was slightly worse than 5.1 $$\pm $$ 0.3 eV before the irradiation. We consider that our TES has sufficient radiation tolerance in orbit. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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15. Development of Active Gas-Gap Heat Switch for Double-Stage Adiabatic Demagnetization Refrigerators.
- Author
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Ishisaki, Y., Henmi, K., Akamatsu, H., Enoki, T., Ohashi, T., Hoshino, A., Shinozaki, K., Matsuo, H., Okada, N., and Oshima, T.
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ADIABATIC demagnetization ,REFRIGERATORS ,MICROFABRICATION ,HEAT conduction ,CHARCOAL ,CALORIMETERS ,HELIUM ,GAS absorption & adsorption - Abstract
We designed and fabricated an active gas-gap heat switch (AGGHS), which ON/OFF the heat conduction between the 1st stage (0.05-2 K) and the 2nd stage (1-4 K) of a double-stage adiabatic demagnetization refrigerator (DADR). Our design geometrically separates two components which dominates the ON or OFF performance, and achieved heat conductivity of 6 mW/K (ON) or 4 μW/K (OFF) at 2 K. The ON/OFF is controlled by a heater attached to the charcoal box to adsorb/deadsorb He gas inside. We introduced the AGGHS to the DADR and successfully cooled the detector stage down to 60 mK, working properly more than a year. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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16. Development of Laboratory Experimental System to Clarify Solar Wind Charge Exchange Mechanism with TES Microcalorimeter.
- Author
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Enoki, T., Ishisaki, Y., Akamatsu, H., Ezoe, Y., Ohashi, T., Kanda, T., Ishida, T., Tanuma, H., Ohashi, H., Shinozaki, K., and Mitsuda, K.
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SOLAR wind ,CHARGE exchange ,CALORIMETERS ,DIFFUSION ,ARTIFICIAL satellites ,NUCLEAR counters ,X-ray astronomy - Abstract
Significant fraction of the cosmic diffuse soft X-ray emission (0.1-1 keV) is caused by the Solar Wind Charge eXchange (SWCX) process between the solar wind ion (C, N, O etc.) and the interplanetary neutral matter. It is difficult to identify spectral features of SWCX with the spectral resolution of existing X-ray astronomy satellites. We are developing a laboratory experimental system with transition edge sensor (TES) X-ray microcalorimeters, in order to clarify the SWCX mechanism. This experiment is designed to measure Charge eXchange (CX) X-rays using Electron Cyclotron Resonance Ion Source (ECRIS) that generates multi-charged ions. Emission lines (O: 2p→1s; 654 eV) by CX between O and neutral He atom is aimed to be measured with energy resolution better than 10 eV. The TES microcalorimeter is cooled by a double-stage adiabatic demagnetization refrigerator (DADR), however, our TES microcalorimeter are not working potentially due to magnetic field contamination. This paper reports our experimental system, present results, and future prospects. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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17. Optimization of Structure of Large Format TES Arrays.
- Author
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Yoshitake, H., Ezoe, Y., Yoshino, T., Mukai, K., Ishikawa, K., Mitsuda, K., Yamasaki, N. Y., Ishisaki, Y., Akamatsu, H., Maeda, R., and Takano, T.
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CALORIMETERS ,TRANSITION temperature ,MAGNETIC properties of superconductors ,THERMAL conductivity ,SEMICONDUCTOR etching - Abstract
We fabricated 16 × 16 format arrays of 180 μm square Ti/Au superconducting transition edge X-ray microcalorimeters of which transition temperatures range from 130 to 220 mK. All pixels are wired with Al, and stand on SiO
2 and SiNx membranes that work as a weak thermal link. The membrane structure is formed by deep reactive ion etching. Energy resolution of a pixel in the array without a Au absorber was 11 eV (FWHM) at 5.9 keV, while the baseline resolution is about 3.7 eV. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
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