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We have developed a four-pixel array of superconducting transition-edge sensors with gold absorbers for the detection of a 29.2 keV γ -ray doublet decay from 229 Th. To identify the decay, an energy resolution better than 20 eV full width at half maximum (FWHM) is needed. We measured an energy resolution of 14 eV FWHM for 26 keV γ -ray decay from an 241 Am isotope in combined data of three pixels. We describe the design and the performance of the devices and discuss the baseline correction method to compensate the variation in the baseline, which was observed during the evaluation of the performance using the 241 Am isotope. [ABSTRACT FROM AUTHOR]

We report the fabrication and evaluation of the Cu/Bi bilayer absorber with electrodeposition. We designed the Cu/Bi absorber to satisfy the requirements for scanning transmission electron microscope (STEM). The residual resistivity ratios of films of Cu and Bi with electrodeposition was $${5.91\pm 0.49}$$ and $${2.06\pm 0.33}$$ , respectively; these values are sufficient for the requirements of STEM. We found that the Cu/Bi bilayer absorber TES microcalorimeter experienced a pulse-shape variation and we considered that these variations were caused by the quality of the contact surface between the absorber and TES. In addition, we examined the structure of the absorber using focus ion beam analysis and STEM. The results suggest that an oxidation between the Cu and seed layer, in which the layer is an electrode for electrodeposition, yielded variations. Moreover, thermal simulation suggests that the thermal conduction between the absorber and TES caused variations. The results of this study will improve the process of Bi electrodeposition. [ABSTRACT FROM AUTHOR]

Background:A proportion of obese subjects appear metabolically healthy (MHO) but little is known about the natural history of MHO and factors predicting its future conversion to metabolically unhealthy obese (MUO).Objectives:The aim was to determine prospectively the frequency of conversion of MHO to MUO and the clinical variables that independently predicted this conversion, with a particular focus on the role of body composition.Methods:We identified 85 Japanese Americans with MHO (56 men, 29 women), aged 34-73 years (mean age 49.8 years) who were followed at 2.5, 5 and 10 years after enrollment with measurements of metabolic characteristics, lifestyle and abdominal and thigh fat areas measured by computed tomography. Obesity was defined using the Asian body mass index criterion of ⩾25 kg m−2. Metabolically healthy was defined as the presence of ⩽2 of 5 metabolic syndrome components proposed by the National Cholesterol Education Program Adult Treatment Panel III, while metabolically unhealthy was defined as ⩾3 components.Results:Over 10 years of follow-up, 55 MHO individuals (64.7%) converted to MUO. Statistically significant univariate predictors of conversion included dyslipidemia, greater insulin resistance and greater visceral abdominal (VAT) and subcutaneous abdominal fat area (SAT). In multivariate analysis, VAT (odds ratio per 1-s.d. increment (95% confidence interval) 2.04 (1.11-3.72), P=0.021), high-density lipoprotein (HDL) cholesterol (0.24 (0.11-0.53), P<0.001), fasting plasma insulin (2.45 (1.07-5.62), P=0.034) and female sex (5.37 (1.14-25.27), P=0.033) were significantly associated with future conversion to MUO. However, SAT was not an independent predictor for future conversion to MUO.Conclusions:In this population, MHO was a transient state, with nearly two-thirds developing MUO over 10 years, with higher conversion to MUO independently associated with VAT, female sex, higher fasting insulin level and lower baseline HDL cholesterol level. [ABSTRACT FROM AUTHOR]

A 57 Fe nucleus in the solar core could emit a 14.4-keV monochromatic axion through the M1 transition if a hypothetical elementary particle, axion, exists to solve the strong CP problem. Transition edge sensor (TES) X-ray microcalorimeters can detect such axions very efficiently if they are again converted into photons by a 57 Fe absorber. We have designed and produced a dedicated TES array with 57 Fe absorbers for the solar axion search. The iron absorber is set next to the TES, keeping a certain distance to reduce the iron-magnetization effect on the spectroscopic performance. A gold thermal transfer strap connects them. A sample pixel irradiated from a 55 Fe source detected 698 pulses. In contrast to thermal simulations, we consider that the pulses include either events produced in an iron absorber or gold strap at a fraction dependent on the absorption rate of each material. Furthermore, photons deposited on the iron absorber are detected through the strap as intended. The identification of all events still needs to be completed. However, we successfully operated the TES with the unique design under iron magnetization for the first time. [ABSTRACT FROM AUTHOR]

This study attempted to develop detection methods for solar axions using transition-edge-sensor (TES) microcalorimeters. Since the axion absorber comprised of iron-57 (57Fe) is electroplated upon the membrane instead of directly onto the TES itself (with the absorber hence thermally connected to the TES via a gold thermal strap), some of the heat deposited into the absorber consequently escapes into the heat bath through the membrane before being detected by the TES. If the heat-loss depends upon the axion interaction position within the absorber, position dependence may degrade the energy resolution. Therefore, this study endeavored to evaluate the dependence of heat-loss and pulse shape on axion incident position with the COMSOL Multiphysics software package (using a finite element method). In addition, heat-loss and pulse shape were likewise evaluated when the energy was deposited directly within the gold thermal strap. [ABSTRACT FROM AUTHOR]

We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate ( $$>$$ 20 kcps), wide energy band (0.5-15 keV) and good energy resolution ( $$<$$ 10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an $$8 \times 8$$ format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 $$\upmu $$ s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed. [ABSTRACT FROM AUTHOR]

We built an in-house oligonucleotide array on which 394 genes were selected based on our Serial Analysis of Gene Expression (SAGE) data and previously reported array data and listed several genes related to cancer progression. Among these, we focused on SEC11A, which encodes the SPC18 protein. SEC11A mRNA expression was measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in gastric cancer (GC) tissue samples. Expression and distribution of SPC18 protein were investigated by immunohistochemical analysis in two independent GC cohorts (Hiroshima cohort, n=99 and Chiba cohort, n=989). To determine the effect of SPC18 on cell viability and invasiveness in vitro, MTT and Boyden chamber invasion assays were performed. To evaluate the influence of SPC18 on cell growth in vivo, GC cells were injected into severe combined immunodeficiency mice. Levels of TGF-α and EGF in media from the GC cells were measured by enzyme-linked immunosorbent assay (ELISA). Studies in human tissue revealed overexpression of SEC11A mRNA in 40% of 42 GC samples by qRT-PCR. Immunohistochemical analysis of SPC18 revealed that 26 and 20% of GC cases were SPC18-positive in the Hiroshima and Chiba cohorts, respectively. In both cohorts, the Kaplan-Meier analysis showed poorer survival in SPC18-positive GC cases than in SPC18-negative GC cases. Forced expression of SPC18 activates GC cell growth in vitro and in vivo. The levels of TGF-α in culture media from GC cells were reduced by knockdown of SPC18. These results indicate that SPC18 contributes to malignant progression through promotion of TGF-α secretion in GC. [ABSTRACT FROM AUTHOR]

We are developing position-sensitive transition-edge sensor (TES) microcalorimeters (PoSTs) to detect gamma rays up to a few MeV. Each gamma-ray PoST consists of a long absorber with a TES on each end and works as a 1D imaging spectrometer. We fabricated PoSTs with 0.5 × 0.5 × 18.8 mm lead absorbers. We irradiated two PoST devices with gamma rays from a Cs-137 source. Gamma-ray pulses of the PoSTs show a strong correlation between the pulse height and the rise time. We divided the pulses in the 662 keV line into 12 groups after sorting them by rise time to determine effective pixels. We modeled the PoST device and compared the average pulses of the 12 effective pixels to numerical simulations. The actual pulses and simulated pulses were in good agreement. [ABSTRACT FROM AUTHOR]

Exotic atom experiments place transition-edge sensor (TES) microcalorimeter arrays in a high-energy charged particle-rich environment. When a high-energy charged particle passes through the silicon substrate of a TES array, a large amount of energy is deposited and small pulses are generated across multiple pixels in the TES array due to thermal crosstalk. We have developed analysis techniques to assess and reduce the effects of charged particle events on exotic atom X-ray measurements. Using this technique, the high-energy and low-energy components of the X-ray peaks due to pileup are eliminated, improving the energy resolution from 6.6 to 5.7 eV at 6.9 keV. [ABSTRACT FROM AUTHOR]

A novel triggering function developed for 240-pixel Transition-Edge Sensors is demonstrated under the high rate of particle background. The function is integrated into the standard data acquisition system in the NIST TES framework. It enables any type of combination of trigger pattern when a pixel is triggered, which is called "group trigger." As a practical implementation, the primary trigger is distributed to the four physically nearest pixels. The group trigger function was utilized throughout the entire one-month J-PARC experiment for the measurement of the Kaonic-atom X-rays. This trigger allowed us to confirm that the increased background and degraded energy resolution we observed when operating the TES array in the presence of an ion beam are the result of thermal crosstalk from charged particles. We show that the maximum of the average of the signals among the neighboring four pixels is useful for event selection. We use cuts based on this parameter to improve the peak-to-background level in a measured x-ray energy spectrum by a factor of ∼ 2, while keeping 95% of measured events. This flexible group triggering technique allows us to improve the signal to noise on the very faint Kaonic Helium x-ray lines we are measuring, better understand our experiment environment, and we believe this technique may prove useful in other ground and space-based TES applications. [ABSTRACT FROM AUTHOR]

A useful function, called group trigger, is implemented in a data acquisition system of a 240-pixel X-ray transition-edge sensor array to store simultaneous waveforms from any desired set of pixels. It works as a diagnostic tool which can record both primary pulses and associated crosstalk events with enough freedom to optimize the data output. Under a high rate of charged particle background, such as in an accelerator, investigating signals from any combination of trigger patterns for a particular event is of high importance. We utilized this function throughout an entire experiment at J-PARC, measuring kaonic atom X-rays in 2018. This was the first time a group trigger was applied to exotic-atom spectroscopy. In this experiment, the primary trigger was distributed to the four physical nearest neighbor pixels for practical purposes. The function clarified the effect of thermal and electrical cross talk from X-rays and charged particles, resulting in a better understanding of the behavior of the TES array in such a high-background environment. [ABSTRACT FROM AUTHOR]

We integrated a TES X-ray spectrometer with a charged kaon beam line at J-PARC to perform X-ray spectroscopy of kaonic helium atoms. Limited beam intensity and a broad beam spot size made it crucial to increase the detector acceptance angle as much as possible, requiring significant development. To this end, our TES system shared the same vacuum with a cryogenic system of the liquid helium experimental target. We also specially developed a target cell for liquid helium and a thinned aperture array on top of the TES detector. Additionally, thermal and magnetic shields and infrared filters were optimized in terms of a larger acceptance angle and energy resolution of the detector. The scientific campaign was performed in June, 2018, where the whole system was stably operated for almost one month. [ABSTRACT FROM AUTHOR]

Several issues in developing transition edge sensor (TES) microcalorimeters for the search of monochromatic solar axions expected at 14.4 keV are studied. The potential problem of developing TES's of this purpose is in that an axion absorber of 57 Fe must be placed in close vicinity of a TES. We estimated the minimum distance to avoid magnetic interference from iron using magnetic FEM simulations, and found it 30 μ m for an iron of 5 μ m thickness. We fabricated a TES with a 10 μ m thick iron membrane separated by 60 μ m. We confirmed the superconducting transition for this TES. However, both the residual normal resistance and the transition temperature was different from those of TES without iron. We also estimated the low-temperature thermal conductivity of an iron membrane by measuring the low-temperature electrical resistance and by applying the Wiedemann–Franz law. We estimated the pulse-shape dependency on the interaction position within the 57 Fe converted using thermal FEM simulations. We found that the pulse-shape variations will limit the energy resolution to about 30 eV FWHM. [ABSTRACT FROM AUTHOR]

The updated program of the future Japanese X-ray satellite mission Diffuse Intergalactic Oxygen Surveyor (DIOS), called as Super DIOS, is planned to search for dark baryons in the form of warm-hot intergalactic medium (WHIM) with high-resolution X-ray spectroscopy. The mission will detect redshifted emission lines from OVII, OVIII and other ions, leading to an overall understanding of the physical nature and spatial distribution of dark baryons as a function of cosmological timescale. We have started the conceptual design of the satellite and onboard instruments, focusing on the era of 2030s. The major change will be an improved angular resolution of the X-ray telescope. Super DIOS will have a 10-arcsec resolution, which is an improvement by a factor of about 20 over DIOS. With this resolution, most of the contaminating X-ray sources will be separated, and the level of the diffuse X-ray background will be much reduced after subtraction of point sources. This will give us higher sensitivity to map out the WHIM in emission. [ABSTRACT FROM AUTHOR]

We have first demonstrated the cooperation between an X-ray TES and a directly coupled microwave SQUID multiplexer (D-coup. MW-Mux) in which SQUIDs are directly coupled to resonators. Using D-coup. MW-Mux, we successfully detected the X-ray pulses from a single-pixel TES and evaluated the energy resolution of 11.8 eV FWHM at 5.9 keV. We found this preliminary energy resolution is attributed to non-optimum bias point of the present TES, which can be improved by the future reduction of readout noise. [ABSTRACT FROM AUTHOR]

We present the latest update and progress on the future Japanese X-ray satellite mission Diffuse Intergalactic Oxygen Surveyor (DIOS). DIOS is proposed to JAXA as a small satellite mission, and would be launched with an Epsilon rocket. DIOS would carry on the legacy of ASTRO-H, which carries semiconductor-based microcalorimeters and is scheduled to be launched in 2016, in high-resolution X-ray spectroscopy. A 400-pixel array of transition-edge sensors (TESs) would be employed, so DIOS would also provide valuable lessons for the next ESA X-ray mission ATHENA on TES operation and cryogen-free cooling in space. We have been sophisticating the entire design of the satellite to meet the requirement for the Epsilon payload for the next call. The primary goal of the mission is to search for warm-hot intergalactic medium with high-resolution X-ray spectroscopy by detecting redshifted emission lines from OVII and OVIII ions. The results would have significant impacts on our understanding of the nature of 'dark baryons,' their total amount and spatial distribution, as well as their evolution over cosmological timescales. [ABSTRACT FROM AUTHOR]

A transition edge sensor (TES) microcalorimeter array as an X-ray sensor for a scanning transmission electron microscope system is being developed. The technical challenge of this system is a high count rate of $$\sim $$ 5000 counts/second/array. We adopted a 64 pixel array with a parallel readout. Common SQUID bias, and common TES bias are planned to reduce the number of wires and the resources of a room temperature circuit. The reduction rate of wires is 44 % when a 64 pixel array is read out by a common bias of 8 channels. The possible degradation of the energy resolution has been investigated by simulations and experiments. The bias fluctuation effects of a series connection are less than those of a parallel connection. Simple calculations expect that the fluctuations of the common SQUID bias and common TES bias in a series connection are $$10^{-7}$$ and $$10^{-3}$$ , respectively. We constructed 8 SQUIDs which are connected to 8 TES outputs and a room temperature circuit for common bias readout and evaluated experimentally. Our simulation of crosstalk indicates that at an X-ray event rate of 500 cps/pixel, crosstalk will broaden a monochromatic line by about 0.01 %, or about 1.5 eV at 15 keV. Thus, our design goal of 10 eV energy resolution across the 0.5-15 keV band should be achievable. [ABSTRACT FROM AUTHOR]