Browsing by Author "Miniussi, Antoine R."
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Item Design and Performance of Hybrid Arrays of Mo/Au Bilayer Transition-Edge Sensors(IEEE, 2017-01-19) Yoon, Wonsik; Adams, Joseph S.; Bandler, Simon R.; Betancourt-Martinez, Gabriele L.; Miniussi, Antoine R.; Porter, Frederick Scott; Sadleir, John E.; Sakai, Kazuhiro; Smith, Stephen J.; Wakeham, Nicholas; et alFor future X-ray astrophysics missions, X-ray microcalorimeters can be optimized with different properties in different regions of the focal plane. This approach has the potential to improve microcalorimeter instrument capabilities with efficient use of instrument resources. For example a point-source array optimized for high angular resolution, high count-rate observations could be accompanied by a main array to expand the field of view for diffuse observations. In this approach, it is desirable to be able to simultaneously optimize different transition-edge sensor (TES) geometries on a single wafer design. The key properties of TESs such as transition temperature and shape are a strong function of size and geometry due to the complex interplay between the proximity effect from the superconducting bias electrodes and the normal metal features used for noise suppression and absorber contact. As a result, devices fabricated with the same deposited layer but with different sizes will have different transition temperatures and different response to X-ray events. In this paper, we present measurements of the transition temperature and properties of devices with different sizes and normal metal features, and discuss how by tuning the geometry we can achieve the desired pixel parameters for a given application. We also describe measurements of transition properties from large-format hybrid arrays containing three different pixel types.Item Extended Line Spread Function of TES Microcalorimeters With Au/Bi Absorbers(IEEE, 2019-03-06) Eckart, Megan E.; Adams, Joseph S.; Bandler, Simon R.; Beaumont, Sophie; Chervenak, James A.; Datesman, Aaron M.; Finkbeiner, Fred M.; Hummatov, Ruslan; Kelley, Richard L.; Kilbourne, Caroline A.; Leutenegger, Maurice A.; Miniussi, Antoine R.; Moseley, Samuel J.; Porter, F. Scott; Sadleir, John E.; Sakai, Kazuhiro; Smith, Stephen J.; Wakeham, Nicholas; Wassell, Edward J.Microcalorimeters have the potential to provide line shapes well described by a single Gaussian broadening term of few-eV width. This attribute makes the detectors especially well suited for x-ray astrophysics observations; however, low-level non-Gaussian broadening terms are expected and must be characterized. These terms depend on the composition of the x-ray absorber, the detailed x-ray absorption physics, the device thermalization processes, and the incident x-ray energy. Here we present the first measurements targeted at understanding the extended line-spread function (LSF) of x-ray microcalorimeter pixels under development for the X-ray Integral Field Unit on the Athena X-ray Observatory. These pixels are composed of Mo/Au transition-edge sensors with overhanging electroplated Au/Bi absorbers. We have measured the line shapes using monochromatic x-ray sources with <1-eV width at several x-ray energies (0.85, 0.93, 1.25, 1.5, 5.4, and 8.0 keV) across the instrument bandpass (0.3–12 keV) and have modeled the line profiles. These results are compared to the extended LSF of the Hitomi microcalorimeter pixels that used HgTe absorbers.Item Fabrication of a Hybrid Transition Edge Sensor Array for LynxWassell, Edward; Adams, Joseph S.; Bandler, Simon R.; Chang, Meng-Ping; Chervenak, James A.; Datesman, Aaron M.; Eckart, Megan E.; Ewin, Audrey J.; Finkbeiner, Fred M.; Yoon Ha, Jong; Kelley, R.; Kilbourne, Caroline A.; Miniussi, Antoine R.; Porter, F.; Sadleir, John E.; Sakai, Kazuhiro; Smith, Stephen J.; Wakehan, NicholasItem Mitigation of Finite Bandwidth Effects in Time-Division-Multiplexed SQUID Readout of TES Arrays(IEEE, 2021-03-11) Durkin, Malcolm; Adams, Joseph S.; Bandler, Simon R.; Chervenak, James A.; Miniussi, Antoine R.; Sakai, Kazuhiro; Smith, Stephen J.; Wakeham, Nicholas; et alTime division multiplexing (TDM) is being developed as the readout technology of the X-ray integral field unit (X-IFU), a 3,168-pixel X-ray transition-edge sensor (TES) imaging spectrometer that is part of the European Space Agency's Athena satellite mission. Recent improvements in the low X-ray event count rate performance of TDM have been driven by increases in multiplexer bandwidth and the mitigation of settling transients. These methods and design changes have improved the 32-row multiplexed resolution of a NASA LPA 2.5a array from an initial (2.73 ± 0.03) eV to (1.97 ± 0.01) eV resolution at 5.9 keV. We discuss these recent advances in TDM readout, which have been implemented in an 8-column × 32-row spectrometer that will be deployed at the Lawrence Livermore National Laboratory electron beam ion trap (EBIT) facility, and present a model that will inform the design of future systems.Item Thermal Crosstalk Measurements and Simulations for an X-ray Microcalorimeter Array(Springer, 2020-01-18) Miniussi, Antoine R.; Adams, Joseph S.; Bandler, Simon R.; Beaumont, Sophie; Chang, Meng P.; Chervenak, James A.; Finkbeiner, Fred M.; Ha, Jong Y.; Hummatov, Ruslan; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E.; Sakai, Kazuhiro; Smith, Stephen J.; Wakeham, Nicholas A.; Wassell, Edward J.Arrays of high-density microcalorimeters require careful heat sinking in order to minimize the thermal crosstalk between nearby pixels. For the array of microcalorimeters developed for the Athena X-ray Integral Field Unit instrument, which has more than 3000 pixels on a 275 µm pitch, it is essential to address this problem in order to meet the energy-resolution requirements. The instrument’s energy-resolution budget requires that the impact of the thermal crosstalk on the energy resolution be a contribution that, added in quadrature to other energy-resolution contributions, is less than 0.2 eV. This value results in a derived requirement that the ratio between the amplitude of the crosstalk signal to an X-ray pulse (for example at 6 keV) is less than 1 × 10−3 (for the first neighbor), less than 4 × 10−4 (for the diagonal neighbor) and less than 8 × 10−5 (for the second nearest neighbor). We have measured the thermal crosstalk levels between pixels in various geometries and configurations. The results show a crosstalk ratio which is at least a factor of 4 lower than the derived requirement. We also developed a finite element (FEM) 2D thermal model to predict the thermal behavior of large-scale arrays. This model successfully simulates the measured data in terms of pulse amplitude and time constants.Item Thermal Impact of Cosmic Ray Interaction with an X-Ray Microcalorimeter Array(Springer Nature Switzerland AG., 2020-02-13) Miniussi, Antoine R.; Adams, Joseph S.; Bandler, Simon R.; Beaumont, Sophie; Chang, Meng P.; Chervenak, James A.; Finkbeiner, Fred M.; Ha, Jong Y.; Hummatov, Ruslan; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, Frederick S.; Sadleir, John E.; Sakai, Kazuhiro; Smith, Stephen J.; Wakeham, Nicholas A.; Wassell, Edward J.The X-ray Integral Field Unit (X-IFU) instrument on the Athena mission will be positioned at the Lagrangian point L2 and be subject to cosmic rays generated by astrophysics sources, primarily relativistic protons. Previous simulations have shown that particles of energy higher than 150 MeV will make it through the outer layers of the satellite. They will reach the detector wafer with a rate of 3 cts cm⁻² s⁻¹ and a most probable energy deposited in the Si frame supporting the array at 150 keV. These events can affect the energy resolution of the detectors through the thermal fluctuations that they produce. This study assesses this potential problem and discusses two suggested design approaches to decrease the impact of cosmic ray in order to limit their effect to their allocation of 0.2 eV within the Athena/X-IFU energy-resolution budget. The first is the addition of a coating layer of high heat capacity material (e.g., Pd) and the second is the splitting of this coating into two thermal regions near the TES array to keep the heat away from the array. Implementing these two features is predicted to cause a decrease in the number of events above 1 µK by more than a factor 10 to ~ 1.5 cps when compared to an equivalent design without these features.