297 research outputs found
Current distribution and transition width in superconducting transition-edge sensors
Present models of the superconducting-to-normal transition in transition-edge
sensors (TESs) do not describe the current distribution within a biased TES.
This distribution is complicated by normal-metal features that are integral to
TES design. We present a model with one free parameter that describes the
evolution of the current distribution with bias. To probe the current
distribution experimentally, we fabricated TES devices with different current
return geometries. Devices where the current return geometry mirrors current
flow within the device have sharper transitions, thus allowing for a direct
test of the current-flow model. Measurements from these devices show that
current meanders through a TES low in the resistive transition but flows across
the normal-metal features by 40% of the normal-state resistance. Comparison of
transition sharpness between device designs reveals that self-induced magnetic
fields play an important role in determining the width of the superconducting
transition. [http://dx.doi.org/10.1063/1.4771984]Comment: 5 pages, 4 figure
Optimization and analysis of code-division multiplexed TES microcalorimeters
We are developing code-division multiplexing (CDM) systems for
transition-edge sensor arrays with the goal of reaching multiplexing factors in
the hundreds. We report on x-ray measurements made with a four-channel
prototype CDM system that employs a flux-summing architecture, emphasizing
data-analysis issues. We describe an empirical method to determine the
demodulation matrix that minimizes cross-talk. This CDM system achieves energy
resolutions of between 2.3 eV and 3.0 eV FWHM at 5.9 keV.Comment: 7 pages, 5 figures. Presented at the 14th International Workshop on
Low Temperature Detectors, Heidelberg University, August 1-5, 2011,
proceedings to be published in the Journal of Low Temperature Physic
The Practice of Pulse Processing
The analysis of data from x-ray microcalorimeters requires great care; their
excellent intrinsic energy resolution cannot usually be achieved in practice
without a statistically near-optimal pulse analysis and corrections for
important systematic errors. We describe the essential parts of a
pulse-analysis pipeline for data from x-ray microcalorimeters, including steps
taken to reduce systematic gain variation and the unwelcome dependence of
filtered pulse heights on the exact pulse-arrival time. We find these steps
collectively to be essential tools for getting the best results from a
microcalorimeter-based x-ray spectrometer.Comment: Accepted for publication in J. Low Temperature Physics, special issue
for the proceedings of the Low Temperature Detectors 16 conferenc
High-resolution kaonic-atom x-ray spectroscopy with transition-edge-sensor microcalorimeters
We are preparing for an ultra-high resolution x-ray spectroscopy of kaonic
atoms using an x-ray spectrometer based on an array of superconducting
transition-edge-sensor microcalorimeters developed by NIST. The instrument has
excellent energy resolutions of 2 - 3 eV (FWHM) at 6 keV and a large collecting
area of about 20 mm^2. This will open new door to investigate kaon-nucleus
strong interaction and provide new accurate charged-kaon mass value.Comment: 6 pages, 3 figures, Proceedings of 15th International Workshop on Low
Temperature Detectors (LTD-15, Pasadena, California, June 24-28, 2013), To be
published in a special issue of the Journal of Low Temperature Physics (JLTP
Algorithms for Identification of Nearly-Coincident Events in Calorimetric Sensors
For experiments with high arrival rates, reliable identification of
nearly-coincident events can be crucial. For calorimetric measurements to
directly measure the neutrino mass such as HOLMES, unidentified pulse pile-ups
are expected to be a leading source of experimental error. Although Wiener
filtering can be used to recognize pile-up, it suffers errors due to
pulse-shape variation from detector nonlinearity, readout dependence on
sub-sample arrival times, and stability issues from the ill-posed deconvolution
problem of recovering Dirac delta-functions from smooth data. Due to these
factors, we have developed a processing method that exploits singular value
decomposition to (1) separate single-pulse records from piled-up records in
training data and (2) construct a model of single-pulse records that accounts
for varying pulse shape with amplitude, arrival time, and baseline level,
suitable for detecting nearly-coincident events. We show that the resulting
processing advances can reduce the required performance specifications of the
detectors and readout system or, equivalently, enable larger sensor arrays and
better constraints on the neutrino mass.Comment: To appear in J. Low Temperature Physics. 11 page
Approaches to the Optimal Nonlinear Analysis of Microcalorimeter Pulses
We consider how to analyze microcalorimeter pulses for quantities that are
nonlinear in the data, while preserving the signal-to-noise advantages of lin-
ear optimal filtering. We successfully apply our chosen approach to compute the
electrothermal feedback energy deficit (the "Joule energy") of a pulse, which
has been proposed as a linear estimator of the deposited photon energy.Comment: Accepted by Journal of Low Temperature Physics. Contribution to the
proceedings of Low Temperature Detectors 17, (Kurume Japan, 2017
A Highly Linear Calibration Metric for TES X-ray Microcalorimeters
Transition-edge sensor X-ray microcalorimeters are usually calibrated
empirically, as the most widely-used calibration metric, optimal filtered pulse
height (OFPH), in general has an unknown dependance on photon energy,
. Because the calibration function can only be measured at specific
points where photons of a known energy can be produced, this unknown dependence
of OFPH on leads to calibration errors and the need for
time-intensive calibration measurements and analysis. A calibration metric that
is nearly linear as a function of could help alleviate these
problems. In this work, we assess the linearity of a physically motivated
calibration metric, . We measure calibration pulses in the range 4.5
keV9.6 keV with detectors optimized for 6 keV photons to
compare the linearity properties of to OFPH. In these test data
sets, we find that fits a linear function an order of magnitude
better than OFPH. Furthermore, calibration functions using , an
optimized version of , are linear within the 2-3 eV noise of the
data
Transition-Edge Sensors for Particle Induced X-ray Emission Measurements
In this paper we present a new measurement setup, where a transitionedge
sensor detector array is used to detect X-rays in particle induced X-ray
emission measurements with a 2 MeV proton beam. Transition-edge sensors offer
orders of magnitude improvement in energy resolution compared to conventional
silicon or germanium detectors, making it possible to recognize spectral lines
in materials analysis that have previously been impossible to resolve, and to
get chemical information from the elements. Our sensors are cooled to the
operation temperature (65 mK) with a cryogen-free adiabatic demagnetization
refrigerator, which houses a specially designed X-ray snout that has a vacuum
tight window to couple in the radiation. For the best pixel, the measured
instrumental energy resolution was 3.06 eV full width at half maximum at 5.9
keV.We discuss the current status of the project, benefits of transition-edge
sensors when used in particle induced X-ray emission spectroscopy, and the
results from the first measurements.Comment: 6 pages, 3 figure, LTD-15 proceeding
On low-energy tail distortions in the detector responsefunction of x-ray microcalorimeter spectrometers
We use narrow spectral lines from the x-ray spectra of various highlycharged
ions to measure low-energy tail-like deviations from a Gaussian
responsefunction in a microcalorimter x-ray spectrometer with Au absorbers at
energiesfrom 650 eV to 3320 eV. We review the literature on low energy tails in
othermicrocalorimter x-ray spectrometers and present a model that explains all
thereviewed tail fraction measurements. In this model a low energy tail arises
fromthe combination of electron escape and energy trapping associated with Bi
x-rayabsorbers
Energy calibration of nonlinear microcalorimeters with uncertainty estimates from Gaussian process regression
The nonlinear energy response of cryogenic microcalorimeters is usually
corrected through an empirical calibration. X-ray or gamma-ray emission lines
of known shape and energy anchor a smooth function that generalizes the
calibration data and converts detector measurements to energies. We argue that
this function should be an approximating spline. The theory of Gaussian process
regression makes a case for this functional form. It also provides an important
benefit previously absent from our calibration method: a quantitative
uncertainty estimate for the calibrated energies, with lower uncertainty near
the best-constrained calibration points.Comment: Submitted to J. Low Temperature Physics for the Proceedings of the
19th International Workshop on Low-Temperature Detectors (2021
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