201 research outputs found
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
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
Filters for High Rate Pulse Processing
We introduce a filter-construction method for pulse processing that differs
in two respects from that in standard optimal filtering, in which the average
pulse shape and noise-power spectral density are combined to create a
convolution filter for estimating pulse heights. First, the proposed filters
are computed in the time domain, to avoid periodicity artifacts of the discrete
Fourier transform, and second, orthogonality constraints are imposed on the
filters, to reduce the filtering procedure's sensitivity to unknown baseline
height and pulse tails. We analyze the proposed filters, predicting energy
resolution under several scenarios, and apply the filters to high-rate pulse
data from gamma-rays measured by a transition-edge-sensor microcalorimeter.Comment: 5 pages, 6 figures, 1 tabl
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
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
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
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
A Transition-edge Sensor-based X-ray Spectrometer for the Study of Highly Charged Ions at the National Institute of Standards and Technology Electron Beam Ion Trap
We report on the design, commissioning, and initial measurements of a
Transition-edge Sensor (TES) x-ray spectrometer for the Electron Beam Ion Trap
(EBIT) at the National Institute of Standards and Technology (NIST). Over the
past few decades, the NIST EBIT has produced numerous studies of highly charged
ions in diverse fields such as atomic physics, plasma spectroscopy, and
laboratory astrophysics. The newly commissioned NIST EBIT TES Spectrometer
(NETS) improves the measurement capabilities of the EBIT through a combination
of high x-ray collection efficiency and resolving power. NETS utilizes 192
individual TES x-ray microcalorimeters (166/192 yield) to improve upon the
collection area by a factor of ~30 over the 4-pixel neutron transmutation doped
germanium-based microcalorimeter spectrometer previously used at the NIST EBIT.
The NETS microcalorimeters are optimized for the x-ray energies from roughly
500 eV to 8,000 eV and achieve an energy resolution of 3.7 eV to 5.0 eV over
this range, a more modest (<2X) improvement over the previous
microcalorimeters. Beyond this energy range NETS can operate with various
trade-offs, the most significant of which are reduced efficiency at lower
energies and being limited to a subset of the pixels at higher energies. As an
initial demonstration of the capabilities of NETS, we measured transitions in
He-like and H-like O, Ne, and Ar as well as Ni-like W. We detail the energy
calibration and data analysis techniques used to transform detector counts into
x-ray spectra, a process that will be the basis for analyzing future data
Eliminating the non-Gaussian spectral response of X-ray absorbers for transition-edge sensors
Transition-edge sensors (TES) as microcalorimeters for high-energy-resolution
X-ray spectroscopy are often fabricated with an absorber made of materials with
high Z (for X-ray stopping power) and low heat capacity (for high resolving
power). Bismuth represents one of the most compelling options. TESs with
evaporated bismuth absorbers have shown spectra with undesirable and
unexplained low-energy tails. We have developed TESs with electroplated bismuth
absorbers over a gold layer that are not afflicted by this problem and that
retain the other positive aspects of this material. To better understand these
phenomena, we have studied a series of TESs with gold, gold/evaporated bismuth,
and gold/electroplated bismuth absorbers, fabricated on the same die with
identical thermal coupling. We show that bismuth morphology is linked to the
spectral response of X-ray TES microcalorimeters
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