Browsing by Author "Beaumont, S."
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Item Correcting Energy Estimation Errors Due to Finite Sampling of Transition‑Edge Sensor Data(Springer, 2022-03-30) Witthoeft, M. C.; Adams, J. S.; Bandler, S. R.; Beaumont, S.; Chervenak, J. A.; Eckart, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Miniussi, Antoine; Porter, F. S.; Sakai, K.; Smith, S. J.; Wakeham, Nicholas; Wassell, E. J.We are developing transition-edge sensor microcalorimeters for the X-ray integral field unit (X-IFU) on-board ESA’s Athena space telescope. These detectors will be read out using time-domain multiplexing. Due to the limitations on bandwidth and dynamic range of the readout, the optimally filtered pulse heights of the measured X-ray signals suffer from a nonlinear variation with the exact photon arrival time relative to the sampling points. The shape and magnitude of this variation depend on the photon energy. We describe a method to characterize this energy-dependent variation with few parameters, which can then be interpolated to correct event energies across the whole spectrum. We implement our method on measurements from 200 pixels in a prototype X-IFU kilo-pixel array readout using 8-column × 32-row TDM. We show that the interpolation errors between calibration points, over the energy range 4–12 keV, can be made sufficiently small that they do not adversely impact the measured energy resolution across the full spectral range.Item Demonstration of Fine-Pitch High-Resolution X-ray Transition-Edge Sensor Microcalorimeters Optimized for Energies below 1 keV(Springer Nature Switzerland AG., 2020-03-07) Sakai, K.; Adams, J. S.; Bandler, S. R.; Beaumont, S.; Chervenak, J. A.; Datesman, A. M.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Miniussi, A. R.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Wakeham, N. A.; Wassell, E. J.; Jaeckel, F. T.; McCammon, D.; Eckart, M. E.; Ryu, K.In this paper, we report on X-ray transition-edge sensor (TES) microcalorimeters optimized to have the best possible energy resolution for a limited energy range for the incoming X-rays, such as an energy resolution of 0.3 eV full width half maximum (FWHM) for energies up to ≈0.8keV as is desirable for one of the Lynx X-ray Microcalorimeter subarrays. The test array we have fabricated has 60×60 sensors on a pitch of 50μm, and has 46×46μm² absorbers that are one micrometer thick. We have measured a spectral energy resolution of the same device using 3 eV photons delivered through an optical fiber. For the one-photon 3 eV line, we have obtained an energy resolution of 0.25 eV FWHM, which is consistent with the estimated performance based on the signal size and noise. Further measurements will determine how the energy resolution degrades with energy. Based upon measurements of the TES transition characteristics, it appears that this level of energy resolution should be achievable up to 0.5 keV, and the performance will then gradually degrade to the measured energy resolution of around 2.3 eV at 1.5 keV. In this paper, we describe the full design and characterization of this detector, and discuss the performance limits of pixels designs like this.Item Developments of Laboratory-Based Transition-Edge Sensor Readout Electronics Using Commercial-Off-The-Shelf Modules(Springer, 2022-08-16) Sakai, Kazuhiro; Adams, J. S.; Bandler, S. R.; Beaumont, S.; Chervenak, J. A.; Doriese, W. B.; Durkin, M.; Finkbeiner, F. M.; Hull, S. V.; Kelley, R. L.; Kilbourne, C. A.; Muramatsu, H.; Porter, F. S.; Reintsema, C. D.; Smith, S. J.; Wakeham, Nicholas; Wassel, E. J.We are developing lab-based readout electronics for Transition-edge sensors (TES) using commercial-of-the-shelf (COTS) modules. These COTS modules are advantageous since they increase development speed and keep the cost low. We have developed these electronics to support both non-multiplexed and time-division multiplexing (TDM) readout systems. The system utilizes remote control via Ethernet, and the interface allows many types of measurements to be automated. With the TDM readout system, we have achieved 2.05 eV at 6 keV, 2.1 eV at 7 keV, 2.3 eV at 8 keV, and 2.8 eV at 12 keV with 2-column×32-row multiplexing. We will be using this system in the characterization of detectors for the X-Ray Integral Field Unit (X-IFU) instrument on Athena. In this paper, we present an overview of the design and their performance.Item Extension of the Energy Range Accessible with a TES Using Bath Temperature Variations(Springer, 2020-02-24) Beaumont, S.; Adams, J.S.; Bandler, S. R.; Chervenak, J. A. ; Finkbeiner, F. M.; Hummatov, R.; Kelley, R. L.; Kilbourne, C. A.; Miniussi, Antoine; Porter, F. S.; Sadleir, J. E.; Sakai, Kazuhiro; Smith, S. J.; Wakeham, Nicholas; Wassell, E. J.The energy range of transition-edge sensor (TES) X-ray microcalorimeters with a multiplexed readout depends upon the width and shape of the TES superconducting transition, and also on the dynamic range of the readout. In many detector systems, the multiplexed readout slew rate capability will be the limiting factor for the energy range. In these cases, if we are willing to accept some energy resolution degrada tion, we can signifcantly extend the energy range by increasing the bath temperature of operation, essentially creating a second “extended energy range” mode of opera tion. For example, if we require the very highest energy resolution up to 7 keV, and wish to optimize the design up to this energy, for some measurements it could be very benefcial to have a mode where we can extend the energy range to 15–20 keV even if some energy resolution is sacrifced. In this paper, we explore the trade-of between dynamic range and energy resolution from changing the bath temperature of the TES. We present measurements of TES resolution and slew rate as a function of bath temperature and compare to numerical simulations.Item High-Frequency Noise Peaks in Mo/Au Superconducting Transition-Edge Sensor Microcalorimeters(Springer, 2020-01-13) Wakeham, N. A.; Adams, J. S; Bandler, S. R.; Beaumont, S.; Chang, M. P.; Chervenak, J. A.; Datesman, A. M.; Eckart, M. E.; Finkbeiner, F. M.; Ha, J. Y.; Hummatov, R.; Kelley, R. L.; Kilbourne, C. A.; Miniussi, A. R.; Porter, F. S.; Sadleir, J. E.; Sakai, K.; Smith, S. J.; Wassell, E. J.The measured noise in Mo/Au transition-edge sensor (TES) microcalorimeters produced at NASA has recently been shown to be well described by a two-body electrothermal model with a finite thermal conductance between the X-ray absorber and the TES. In this article, we present observations of a high-frequency peak in the measured current noise in some of these devices. The peak is associated with an oscillatory component of the TES response that is not predicted in a single-body model but can be qualitatively described by the two-body model.Item Quantum Efficiency Study and Reflectivity Enhancement of Au/Bi Absorbers(Springer Nature Switzerland AG., 2020-03-07) Hummatov, R.; Adams, J. S.; Bandler, S. R.; Barlis, A.; Beaumont, S.; Chang, M. P.; Chervenak, J. A.; Datesman, A. M.; Eckart, M. E.; Finkbeiner, F. M.; Ha, J. Y.; Kelley, R. L.; Kilbourne, C. A.; Miniussi, A. R.; Porter, F. S.; Sadleir, J. E.; Sakai, K.; Smith, S. J.; Wakeham, N.; Wassell, E. J.; Wollack, E. J.X-ray absorbers of the X-ray Integral Field Unit (X-IFU) microcalorimeters are required to provide high quantum efficiency (QE) for incident X-rays and high reflectivity to longer wavelength radiation. The thickness of the electroplated Au and Bi layers of the absorber is tuned to provide the desired pixel heat capacity and the QE. To calculate the QE precisely, in addition to filling factor, we have included the effects of surface roughness, edge profile of the absorbers and the effects of the different angles of incidence of the incoming X-rays from the X-IFU optic. Based on this analysis, it is found that thickness of the Bi layer needs to be adjusted by 4.3% to achieve the X-IFU QE requirements. To enhance the absorber’s rejection of low-energy radiation, a second thin layer of Au is sputter-deposited on top of the Bi layer. Optical measurements in the wavelength range 0.3–20 μm show a significant increase in reflectivity compared to a bare Bi layer.Item Quantum Efficiency Study and Reflectivity Enhancement of Au/Bi Absorbers(Springer, 2020-03-07) Hummatov, R.; Adams, J. S.; Bandler, S. R.; Barlis, A.; Beaumont, S.; Miniussi, Antoine; Sadleir, J. E.; Sakai, Kazuhiro; Smith, S. J.; Wakeham, Nicholas; Wassell, E. J.; et alX-ray absorbers of the X-ray Integral Field Unit (X-IFU) microcalorimeters are required to provide high quantum efficiency (QE) for incident X-rays and high reflectivity to longer wavelength radiation. The thickness of the electroplated Au and Bi layers of the absorber is tuned to provide the desired pixel heat capacity and the QE. To calculate the QE precisely, in addition to filling factor, we have included the effects of surface roughness, edge profile of the absorbers and the effects of the different angles of incidence of the incoming X-rays from the X-IFU optic. Based on this analysis, it is found that thickness of the Bi layer needs to be adjusted by 4.3% to achieve the X-IFU QE requirements. To enhance the absorber’s rejection of low-energy radiation, a second thin layer of Au is sputter-deposited on top of the Bi layer. Optical measurements in the wavelength range 0.3–20 μm show a significant increase in reflectivity compared to a bare Bi layer.Item TES pixel optimization for the ATHENA X-IFU instrument(2019-07-22) Wakeham, Nicholas; Adams, J. S.; Bandler, S.; Beaumont, S.; Miniussi, Antoine; Sakai, Kazuhiro; Smith, Stephen J.; et alATHENA is a European led x-ray observatory due for launch in the early 2030s. The X-ray Integral Field Unit (X-IFU) instrument on ATHENA will have an array of 3168 TES microcalorimeters, 2.5 eV resolution (at 7 keV), 5 arc second angular resolution and a 5 arc minute field of view. As one example, will allow unprecedented views of composition and dynamics of galaxy clusters.Item Thermal fluctuation noise in Mo/Au superconducting transition-edge sensor microcalorimeters(AIP, 2019-04-23) Wakeham, Nicholas; Adams, J. S.; Bandler, S. R.; Beaumont, S.; Chervenak, J. A.; Datesman, A. M.; Eckart, M. E.; Finkbeiner, F. M.; Hummatov, R.; Kelley, R. L.; Kilbourne, C. A.; Miniussi, Antoine; Porter, F. S.; Sadleir, J. E.; Sakai, Kazuhiro; Smith, S. J.; Wassell, E. J.In many superconducting transition-edge sensor (TES) microcalorimeters, the measured electrical noise exceeds theoretical estimates based on a thermal model of a single body thermally connected to a heat bath. Here, we report on noise and complex impedance measurements of a range of designs of TESs made with a Mo/Au bilayer. We have fitted the measured data using a two-body model, where the x-ray absorber and the TES are connected by an internal thermal conductance Gae. We find that the so-called excess noise measured in these devices is consistent with the noise generated from the internal thermal fluctuations between the x-ray absorber and the TES. Our fitted parameters are consistent with the origin of Gae being from the finite thermal conductance of the TES itself. These results suggest that even in these relatively low resistance Mo/Au TESs, the internal thermal conductance of the TES may add significant additional noise and could account for all the measured excess noise. Furthermore, we find that around regions of the superconducting transition with rapidly changing derivative of resistance with respect to temperature, an additional noise mechanism may dominate. These observations may lead to a greater understanding of TES devices and allow the design of TES microcalorimeters with improved performance.Item Toward 100,000‑Pixel Microcalorimeter Arrays Using Multi‑absorber Transition‑Edge Sensors(Springer, 2020-02-01) Smith, Stephen J.; Adams, J. S.; Bandler, S. R.; Beaumont, S.; Chervenak, J. A.; Datesman, A. M.; Finkbeiner, F. M.; Hummatov, R.; Kelly, R. L.; Kilbourne, C. A.; Miniussi, Antoine; Porter, F. S.; Sadleir, J. E.; Sakai, Kazuhiro; Wakeham, Nicholas; Wassell, E. J.; Witthoeft, M. C.; Ryu, K.We report on the development of multi-absorber transition-edge sensors (TESs), referred to as ‘hydras’. A hydra consists of multiple X-ray absorbers each with a different thermal conductance to a TES. Position information is encoded in the pulse shape. With some trade-off in performance, hydras enable very large format arrays without the prohibitive increase in bias and readout components associated with arrays of individual TESs. Hydras are under development for the next generation of space telescope such as Lynx. Lynx is a NASA concept under study that will combine a <1″ angular resolution optic with 100,000-pixel microcalorimeter array with energy resolution of ΔEFWHM ~3 eV in the soft X-ray energy range. We present first results from hydras with 25-pixels for Lynx. Designs with absorbers on a 25 μm and 50 μm pitch are studied. Arrays incorporate, for the first time, microstrip buried wiring layers of suitable pitch and density required to readout a full-scale Lynx array. The resolution from the coadded energy histogram including all 25-pixels was ΔEFWHM =1.66±0.02 eV and 3.34±0.06 eV at an energy of 1.5 keV for the 25 μm and 50 μm absorber designs, respectively. Position discrimination is demonstrated from parameterization of the rise-time.