Search

In the field of continuous-variable quantum information processing, non-Gaussian states with negative values of the Wigner function are crucial for the development of a fault-tolerant universal quantum computer. While several non-Gaussian states have been generated experimentally, none have been created using ultrashort optical wave packets, which are necessary for high-speed quantum computation, in the telecommunication wavelength band where mature optical communication technology is available. In this paper, we present the generation of non-Gaussian states on wave packets with a short 8-ps duration in the 1545.32 nm telecommunication wavelength band using photon subtraction up to three photons. We used a low-loss, quasi-single spatial mode waveguide optical parametric amplifier, a superconducting transition edge sensor, and a phase-locked pulsed homodyne measurement system to observe negative values of the Wigner function without loss correction up to three-photon subtraction. These results can be extended to the generation of more complicated non-Gaussian states and are a key technology in the pursuit of high-speed optical quantum computation., 14 pages, 5 figures

Optical transition-edge sensors (TESs) have shown an energy resolution for resolving the number of incident photons at the telecommunication wavelength. However, a higher energy resolution is required for biological imaging and microscopic spectroscopy. In this study, we tested an Au/Ti (10/20 nm) bilayer TES that showed a high energy resolution. The high energy resolution was achieved by lowering the critical temperature T c to 115 mK, and the resultant energy resolution was 67 meV full width at half maximum (FWHM) at 0.8 eV. When T c was reduced to 115 mK, the theoretical resolution would scale up to 30 meV FWHM, considering that the typical energy resolution of optical TESs was 150 meV and T c was 300 mK. To investigate the difference between the theoretical expectation (30 meV) and the measured value (67 meV), we measured the complex impedance and current noise of the TES. We found excess Johnson noise in the TES; the excess Johnson noise term M was 1.5 at a bias point where the resistance was 10% of the normal resistance. For reference, the above mentioned TES was compared with a TES showing typical energy resolution (156 meV FWHM). We also discussed factors that improved or inhibited the energy resolution.

In this work, we remove the timing jitter of the photon-number-resolving detector which limited non-Gaussian state preparation using a continuous-wave light source, and generate a Schrödinger cat state with Wigner negativity.

Photon imaging technology is applied in various research fields such as quantum information communication and biological imaging. We have been developing photon-counting devices using optical transition edge sensors (TES). We demonstrated a single-photon spectroscopic imaging system comprising an optical TES and a scanning microscope. However, a great number of TES pixels are required to increase the field of view in the imaging system. To read out the TES array, output signals need to be multiplexed. Microwave SQUID multiplexer (MW-Mux) is a kind of frequency multiplexing method with a carrier wave having a frequency of several GHz, and it can be used to widen the frequency band. In this paper, we report the first demonstration on readout of an optical TES with MW-Mux.

We developed a Ti/Au bilayer optical superconducting transition edge sensor (TES) laying on an optical fiber self-aligned structure. The bilayer approach enables us to control the superconducting transition temperature T C , which results in 8-μm-square-sized TES with T C as high as 314.0 mK. Moreover, the TES device is micro-machined so that it can be easily assembled with an optical fiber via a self-aligned method. Our TES device achieved a system photon detection efficiency (PDE) of 83.6% at 940 nm with an energy resolution of 0.21 eV. Electrical and effective time constants (rise time and decay time) were as short as 74 and 75 ns, respectively. We also theoretically analyzed the imperfect system PDE. According to this analysis, the imperfection originated mainly from misalignment between the TES and the optical fiber, and the system PDE will be increased up to >95% by use of an optical fiber with a smaller mode field diameter.

Infrared (IR) spectra of resorcinol (Rs)-Arn clusters (n = 1 and 2) have been measured in the neutral and cationic ground states (S0 and D0) by IR dip and resonance-enhanced multiphoton ionization (REMPI)-IR spectroscopy. The OH stretching vibrations in S0 keep their frequency regardless of the number of Ar atoms and the conformation of the OH groups in Rs (rotamers RsI and RsII), demonstrating that the Ar atoms are attached to the aromatic π-ring (π-bound structure) in S0. In the D0 state, the IR spectra of Rs+-Arn reflect the difference in the Rs conformations (RsI+ and RsII+). For n = 1, the IR spectra of both rotamers are almost the same as those of the corresponding monomer cations, indicating that Ar ligands essentially remain π-bonded after ionization. In contrast, the IR spectra of Rs+-Ar2 show hydrogen-bonded and free OH stretching vibrations, demonstrating that for a significant fraction of the clusters, the Ar atoms migrate from the π-bound site to the OH groups. The ionization-induced π → H migration yields are not unity for both rotamers RsI+-Ar2 and RsII+-Ar2. This result is in sharp contrast to phenol+-Ar2, in which one of the Ar atoms migrates to the OH site with 100% yield. The mechanism leading to the nonunity yield in Rs+-Ar2 is discussed in terms of the number of OH binding sites and Franck-Condon factors. The ionization excess energy dependence of the IR spectra of Rs+-Ar2 and its Rs+-Ar fragments is discussed in terms of the Ar binding energies estimated from the photoionization and photodissociation efficiency spectra.

Optical transition-edge sensors (TESs) that can resolve the energy of a single photon have been proven useful in quantum information and biology. TESs can provide spectra ranging from near-infrared to visible regions and have the potential to reveal new phenomena in biology. In this paper, we have investigated the responses of TESs to photons at near-infrared and visible wavelengths, from 450 to 1000 nm in 10-nm increments using a supercontinuum laser and a tunable bandpass filter, which converted the multichromatic light source into monochromatic light. The system detection efficiency of an optical TES optimized for photon detection at 950 nm was nearly 100% at some wavelengths and was more than 10% for the overall bandwidth. We found that the detector responses strongly depended on the wavelengths. A spectrum of the filtered light at shorter wavelengths was more likely to show a second peak with energy lower than that of the primary peak.

The third-generation upgrade to the receiver on the South Pole Telescope, SPT-3G, was installed at the South Pole during the 2016–2017 austral summer to measure the polarization of the cosmic microwave background. Increasing the number of detectors by a factor of 10 to ∼16,000 \ud ∼16,000\ud required the multiplexing factor to increase to 68 and the bandwidth of the frequency-division readout electronics to span 1.6–5.2 MHz. This increase necessitates low-thermal conductance, low-inductance cryogenic wiring. Our cold readout system consists of planar thin-film aluminum inductive–capacitive resonators, wired in series with the detectors, summed together, and connected to 4K SQUIDs by 10−μm \ud 10−μm\ud -thick niobium–titanium (NbTi) broadside-coupled striplines. Here, we present an overview of the cold readout electronics for SPT-3G, including assembly details and characterization of electrical and thermal properties of the system. We report, for the NbTi striplines, values of R≤10 −4 Ω \ud R≤10−4Ω\ud , L=21±1 nH \ud L=21±1 nH\ud , and C=1.47±.02 nF \ud C=1.47±.02 nF\ud . Additionally, the striplines’ thermal conductivity is described by kA=6.0±0.3 T 0.92±0.04 μW mm K −1 \ud kA=6.0±0.3 T0.92±0.04 μW mm K−1\ud . Finally, we provide projections for cross talk induced by parasitic impedances from the stripline and find that the median value of percentage cross talk from leakage current is 0.22 and 0.09% \ud 0.09%\ud from wiring impedance.

Fluorescence color imaging at an extremely low excitation intensity was performed using an optical transition edge sensor (TES) embedded in a confocal microscope for the first time. Optical TES has the ability to resolve incident single photon energy; therefore, the wavelength of each photon can be measured without spectroscopic elements such as diffraction gratings. As target objects, animal cells labeled with two fluorescent dyes were irradiated with an excitation laser at an intensity below $$1\,\upmu \hbox {W}$$ . In our confocal system, an optical fiber-coupled TES device is used to detect photons instead of the pinhole and photomultiplier tube used in typical confocal microscopes. Photons emitted from the dyes were collected by the objective lens, and sent to the optical TES via the fiber. The TES measures the wavelength of each photon arriving in an exposure time of 70 ms, and a fluorescent photon spectrum is constructed. This measurement is repeated by scanning the target sample, and finally a two-dimensional RGB-color image is obtained. The obtained image showed that the photons emitted from the dyes of mitochondria and cytoskeletons were clearly resolved at a detection intensity level of tens of photons. TES exhibits ideal performance as a photon detector with a low dark count rate ( $$

Optical transition edge sensors (TESs) are characterized by a very fast response, of the order of $$\upmu $$ s, which is $$10^3$$ times faster than TESs for X-ray and gamma-ray. To extract important parameters associated with the optical TES, complex impedances at high frequencies (> 1 MHz) need to be measured, where the parasitic impedance in the circuit and reflections of electrical signals due to discontinuities in the characteristic impedance of the readout circuits become significant. This prevents the measurements of the current sensitivity $$\beta $$ , which can be extracted from the complex impedance. In usual setups, it is hard to build a circuit model taking into account the parasitic impedances and reflections. In this study, we present an alternative method to estimate a transfer function without investigating the details of the entire circuit. Based on this method, the complex impedance up to 30 MHz was measured. The parameters were extracted from the impedance and were compared with other measurements. Using these parameters, we calculated the theoretical limit on an energy resolution and compared it with the measured energy resolution. In this paper, the reasons for the deviation of the measured value from theoretically predicted values will be discussed.

Infrared (IR) spectra of resorcinol (Rs)-Ar

著者人数: 152名(所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 羽澄, 昌史; 堂谷, 忠靖; 長谷部, 孝; 今田, 大皓; 満田, 和久; 坂井, 真一郎; 関本, 裕太郎; Tomida, T.; 辻本, 匡弘; Yamamoto, R.; 山崎, 典子), Accepted: 2019-01-18, 資料番号: SA1180402000

The readout of transition-edge sensor (TES) bolometers with a large multiplexing factor is key for the next generation cosmic microwave background (CMB) experiment, Polarbear-2 (Suzuki in J Low Temp Phys 176:719, 2014), having 7588 TES bolometers. To enable the large arrays, we have been developing a readout system with a multiplexing factor of 40 in the frequency domain. Extending that architecture to 40 bolometers requires an increase in the bandwidth of the SQUID electronics, above 4 MHz. This paper focuses on cryogenic readout and shows how it affects cross talk and the responsivity of the TES bolometers. A series resistance, such as equivalent series resistance of capacitors for LC filters, leads to non-linear response of the bolometers. A wiring inductance modulates a voltage across the bolometers and causes cross talk. They should be controlled well to reduce systematic errors in CMB observations. We have been developing a cryogenic readout with a low series impedance and have tuned bolometers in the middle of their transition at a high frequency ( $$>$$ 3 MHz).

Optical transition edge sensor (TES) detectors that can resolve the energy of a single optical photon have proven to be desirable in multicolor fluorescence microscopy. Here, detectors with a higher energy resolution can distinguish dyes having similar or closer emission wavelengths, thus enabling the observation of multiple kinds of dyes simultaneously. To improve energy resolution, it is necessary to know how different the measured energy resolution is from the limit determined by the temperature sensitivity αI and current sensitivity βI, as extracted from the complex impedance. Due to the very fast response of an optical TES (the time constant is shorter than 1 µs), the complex impedance must be measured up to frequencies larger than 10 MHz. However, at high frequencies, the parasitic impedance in the circuit and reflections of electrical signals caused by discontinuities in the characteristic impedance of the readout circuits become significant. To reduce these effects, twisted pair cables are replaced with coaxial ones in this work; thus, a cleaner transfer function of the readout at high frequencies is obtained. The measured impedance of the studied TES is consistent with that given by the single-block model.

Optical transition edge sensors (TESs) which can resolve an energy of a single photon have proven desirable in quantum information and biology. TESs can provide spectra ranging from near-infrared to visible regions, and have the potential to reveal new phenomena in biology. To obtain reliable spectra, wavelength dependence of the system detection efficiency should be calibrated. The dependence is due to a cavity structure of the detector, consisting of an anti-reflection coating and a mirror. We will present a calibration using a supercontinuum laser and acousto-optic tunable filters (AOTF).

Polarbear is a ground-based experiment located in the Atacama desert of northern Chile. The experiment is designed to measure the Cosmic Microwave Background B-mode polarization at several arcminute resolution. The CMB B-mode polarization on degree angular scales is a unique signature of primordial gravitational waves from cosmic inflation and B-mode signal on sub-degree scales is induced by the gravitational lensing from large-scale structure. Science observations began in early 2012 with an array of 1, 274 polarization sensitive antenna-couple Transition Edge Sensor (TES) bolometers at 150 GHz. We published the first CMB-only measurement of the B-mode polarization on sub-degree scales induced by gravitational lensing in December 2013 followed by the first measurement of the B-mode power spectrum on those scales in March 2014. In this proceedings, we review the physics of CMB B-modes and then describe the Polarbear experiment, observations, and recent results.

Low loss superconducting microstrip is an essential component in realizing 100 kilo-pixel multichroic cosmic microwave background detector arrays. We have been developing a low loss microstrip by understanding and controlling the loss mechanisms. We present the fabrication of the superconducting microstrip, the loss measurements at a few GHz frequencies using half-wavelength resonators, and the loss measurements at 220 GHz frequencies with the superconducting microstrip coupled to slot antennas at one end and to TES detectors at the other end. The measured loss tangent of the microstrip made of sputtered Nb and SiOx is 1-2e-3.

著者人数: 152名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 長谷部, 孝; 堂谷, 忠靖; 羽澄, 昌史; 今田, 大皓; 満田, 和久; 坂井, 真一郎; 関本, 裕太郎; Tomida, T.; 辻本, 匡弘; Yamamoto, R.; 山崎, 典子), Accepted: 2018-04-07, 資料番号: SA1180209000

© 2002-2011 IEEE. In this paper, we describe the optimization of transition-edge-sensor (TES) detector arrays for the third-generation camera for the South Pole Telescope. The camera, which contains ~ 16 000 detectors, will make high-angular-resolution maps of the temperature and polarization of the cosmic microwave background. Our key results are scatter in the transition temperature of Ti/Au TESs is reduced by fabricating the TESs on a thin Ti(5 nm)/Au(5 nm) buffer layer and the thermal conductivity of the legs that support our detector islands is dominated by the SiOx dielectric in the microstrip transmission lines that run along the legs.

We report an improved measurement of the cosmic microwave background B-mode polarization power spectrum with the Polarbear experiment at 150 GHz. By adding new data collected during the second season of observations (2013-2014) to re-analyzed data from the first season (2012-2013), we have reduced twofold the band-power uncertainties. The band powers are reported over angular multipoles 500 ≤ ℓ ≤ 2100, where the dominant B-mode signal is expected to be due to the gravitational lensing of E-modes. We reject the null hypothesis of no B-mode polarization at a confidence of 3.1σ including both statistical and systematic uncertainties. We test the consistency of the measured B-modes with the Λ Cold Dark Matter (ΛCDM) framework by fitting for a single lensing amplitude parameter A L = 0.60 +0.26-0.24(stat)+0.00-0.04 (inst) ± 0.14(foreground) ± 0.04(multi), where A L = 1 relative to the Planck 2015 best-fit model prediction. We obtain ±0.14(foreground) ±0.04(multi), where is the fiducial ΛCDM value.

We present an overview of the design and development of the POLARBEAR-2 experiment. The POLARBEAR-2 experiment is a cosmic microwave background polarimetry experiment, which aims to characterize the small angular scale B-mode signal due to gravitational lensing and search for the large angular scale B-mode signal from inflationary gravitational waves. The experiment will have a 365 mm diameter multi-chroic focal plane filled with 7,588 polarization sensitive antenna-coupled Transition Edge Sensor bolometers and will observe at 95 and 150 GHz. The focal plane is cooled to 250 mK. The bolometers will be read-out by SQUIDs with $$32\times $$ frequency domain multiplexing. The experiment will utilize high purity alumina lenses and thermal filters to achieve the required high optical throughput. A continuously rotating, cooled half-wave plate will be used to give stringent control over systematic errors. The experiment is designed to achieve a noise equivalent temperature of 5.7 $$\mu $$ K $$\sqrt{s}$$ , and this allows us to constrain the signal from the inflationary primordial gravitational corresponding to a tensor-to-scalar ratio of $$r = 0.01$$ ( $$2\sigma $$ ). POLARBEAR-2 will also be able to put a constraint on the sum of neutrino masses to 90 meV ( $$1\sigma $$ ) with POLARBEAR-2 data alone and 65 meV ( $$1\sigma $$ ) when combined with the Planck satellite. We plan to start observations in 2014 in the Atacama Desert in Chile.

The polarbear cosmic microwave background (CMB) polarization experiment has been observing since early 2012 from its 5,200 m site in the Atacama Desert in Northern Chile. polarbear’s measurements will characterize the expected CMB polarization due to gravitational lensing by large scale structure, and search for the possible B-mode polarization signature of inflationary gravitational waves. polarbear’s 250 mK focal plane detector array consists of 1,274 polarization-sensitive antenna-coupled bolometers, each with an associated lithographed band-defining filter and contacting dielectric lenslet, an architecture unique in current CMB experiments. The status of the polarbear instrument, its focal plane, and the analysis of its measurements are presented.

We present a status of the development of microwave kinetic inductance detectors (MKIDs) for a detection of athermal phonons in a substrate. The energy deposited in the substrate is converted to athermal phonons. Athermal phonons arriving at the surface can break Cooper pairs in the MKIDs which are formed as a thin superconducting metal layer in the substrate surface. By counting the number of Cooper pairs broken and measuring the phonon arrival times, we can measure the amount of deposited energy and its position. MKIDs are suitable for the frequency-domain multiplexing readout, which enables us to readout hundreds of pixels simultaneously and, hence, to detect athermal phonons with a large detection efficiency. We fabricated MKIDs with a combination of aluminum and niobium on a silicon substrate, and then irradiated it with \(\alpha \) particles from an \(^{241}\)Am source. We detected phonons and made a rough estimation of the phonon propagation velocity of 1.1–1.3 km/s. We found that a thin insulator layer can block the phonon propagation from the substrate to the thin metal layer.

Primordial gravitational waves generated by inflation have produced an odd-parity pattern B-mode in the cosmic microwave background (CMB) polarization. LiteBIRD (Light satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection) aims at detecting this B-mode polarization precisely. It requires about 2000 detectors capable of detecting a frequency range from 50 GHz to 250 GHz with ultra low noise. Superconducting detectors are suitable for this requirement. We have fabricated and tested microwave kinetic inductance detectors (MKIDs) and developed a new readout system. We have designed antenna-coupled MKIDs. Quasi-particles are created by incident radiation and are detected as a change of the surface impedance of a superconductor strip. This change of the surface impedance is translated into the change of the resonant frequency of a microwave signal transmitted through the resonator. We also have developed a new readout system for MKIDs. The newly developed readout system is not only able to read out the amplitude and the phase data with the homodyne detection for multi-channels, but also provides a unique feature of tracking the resonant frequency of the target resonator. This mechanism enables us to detect signals with a large dynamic range. We report on the recent R&D status of the developing MKIDs and on the read-out system for LiteBIRD.

We have developed a prototype time-resolved neutron imaging detector employing the micro-pixel chamber (muPIC), a micro-pattern gaseous detector, coupled with a field programmable gate array-based data acquisition system for applications in neutron radiography at high-intensity neutron sources. The prototype system, with an active area of 10cm x 10cm and operated at a gas pressure of 2 atm, measures both the energy deposition (via time-over-threshold) and 3-dimensional track of each neutron-induced event, allowing the reconstruction of the neutron interaction point with improved accuracy. Using a simple position reconstruction algorithm, a spatial resolution of 349 +/- 36 microns was achieved, with further improvement expected. The detailed tracking allows strong rejection of background gamma-rays, resulting in an effective gamma sensitivity of 10^-12 or less, coupled with stable, robust neutron identification. The detector also features a time resolution of 0.6 microseconds., 10 pages, 13 figures; accepted for publication in NIMA

We have developed a prototype time-resolved neutron imaging detector employing a micro-pattern gaseous detector known as the micro-pixel chamber ({\mu}PIC) coupled with a field-programmable-gate-array-based data acquisition system. Our detector system combines 100{\mu}m-level spatial and sub-{\mu}s time resolutions with a low gamma sensitivity of less than 10^-12 and high data rates, making it well suited for applications in neutron radiography at high-intensity, pulsed neutron sources. In the present paper, we introduce the detector system and present several test measurements performed at NOBORU (BL10), J-PARC to demonstrate the capabilities of our prototype. We also discuss future improvements to the spatial resolution and rate performance.

The third generation receiver for the South Pole Telescope, SPT-3G, will make extremely deep, arcminuteresolution maps of the temperature and polarization of the cosmic microwave background. The SPT-3G maps will enable studies of the B-mode polarization signature, constraining primordial gravitational waves as well as the effect of massive neutrinos on structure formation in the late universe. The SPT-3G receiver will achieve exceptional sensitivity through a focal plane of ~16,000 transition-edge sensor bolometers, an order of magnitude more than the current SPTpol receiver. SPT-3G uses a frequency domain multiplexing (fMux) scheme to read out the focal plane, combining the signals from 64 bolometers onto a single pair of wires. The fMux readout facilitates the large number of detectors in the SPT-3G focal plane by limiting the thermal load due to readout wiring on the 250 millikelvin cryogenic stage. A second advantage of the fMux system is that the operation of each bolometer can be optimized. In addition to these benefits, the fMux readout introduces new challenges into the design and operation of the receiver. The bolometers are operated at a range of frequencies up to 5 MHz, requiring control of stray reactances over a large bandwidth. Additionally, crosstalk between multiplexed detectors will inject large false signals into the data if not adequately mitigated. SPT-3G is scheduled to deploy to the South Pole Telescope in late 2016. Here, we present the pre-deployment performance of the fMux readout system with the SPT-3G focal plane.

Detectors for cosmic microwave background (CMB) experiments are now essentially background limited, so a straightforward alternative to improve sensitivity is to increase the number of detectors. Large arrays of multichroic pixels constitute an economical approach to increasing the number of detectors within a given focal plane area. Here, we present the fabrication of large arrays of dual-polarized multichroic transition-edge-sensor (TES) bolometers for the South Pole Telescope third-generation CMB receiver (SPT-3G). The complete SPT-3G receiver will have 2690 pixels, each with six detectors, allowing for individual measurement of three spectral bands (centered at 95 GHz, 150 GHz and 220 GHz) in two orthogonal polarizations. In total, the SPT-3G focal plane will have 16140 detectors. Each pixel is comprised of a broad-band sinuous antenna coupled to a niobium microstrip transmission line. In-line filters are used to define the different band-passes before the millimeter-wavelength signal is fed to the respective Ti/Au TES sensors. Detectors are read out using a 64x frequency domain multiplexing (fMux) scheme. The microfabrication of the SPT-3G detector arrays involves a total of 18 processes, including 13 lithography steps. Together with the fabrication process, the effect of processing on the Ti/Au TES’s Tc is discussed. In addition, detectors fabricated with Ti/Au TES films with Tc between 400 mK 560 mK are presented and their thermal characteristics are evaluated. Optical characterization of the arrays is presented as well, indicating that the response of the detectors is in good agreement with the design values for all three spectral bands (95 GHz, 150 GHz, and 220 GHz). The measured optical efficiency of the detectors is between 0.3 and 0.8. Results discussed here are extracted from a batch of research of development wafers used to develop the baseline process for the fabrication of the arrays of detectors to be deployed with the SPT-3G receiver. Results from these research and development wafers have been incorporated into the fabrication process to get the baseline fabrication process presented here. SPT-3G is scheduled to deploy to the South Pole Telescope in late 2016.

We have successfully refined the position resolution of a two-dimensional X-ray photon-counting detector based on the micro-pixel gas chamber (μ-PIC) by measuring the charge distribution of an X-ray interaction without the use of analog-to-digital converters (ADCs). By updating the logic of the Field Programmable Gate Arrays (FPGAs) included in the data acquisition system, we were able to acquire the pulse widths, or time-above-threshold of the μ-PIC signals, by measuring both the leading and trailing edges of the digital signals. By using the measured widths to estimate the peak of the charge distribution, the position resolution of our detector was improved to σ=93.3±2.8μm from a value of σ=229.5±6.8μm found using the FPGA logic of the previous system. This represents an improvement of nearly 60%.

The satellite LiteBIRD (Light satellite for the studies of B-mode polarization and Inflation from cosmic background Radiation Detection) is being designed to detect the B-mode polarization of the cosmic microwave background radiation. LiteBIRD will carry about 2,000 detectors for measurements in five bands (60, 80, 100, 150, and 220 GHz). Microwave kinetic inductance detectors (MKIDs) that can be multiplexed in a single readout line are suitable for the large focal plane detector array. We develop an MKID readout system for LiteBIRD to monitor the amplitude, phase, and resonant frequency of each MKID resonator simultaneously and follow movements of the resonant frequency caused by changes in the input radiation intensity. This mechanism enables us to have a larger dynamic range for the MKIDs, compared with a system that monitors the amplitude and phase on the resonant frequency. We also propose an MKID having a half-wavelength resonator. This MKID transmits the resonant microwave signal from one feedline to another. It can offer clear microwaves passing through the resonators, even if the coupling and internal quality factors are mismatched. With this MKID, our readout system can track resonance frequency changes much more easily. We present the status of the readout system development and demonstrate the performance with the half-wavelength MKID.

We present our recent development of superconducting detectors for measurements of cosmic microwave background. We have fabricated antenna-coupled superconducting tunnel junctions (STJs). Two different types of STJs have been fabricated: the parallel-connected twin junction and the microstrip. Both types of STJs made of Nb and Al have successfully detected 80 GHz millimeter wave radiation with photon-assisted tunneling. We have also developed microwave kinetic inductance detectors (MKIDs). The MKIDs offer us high multiplexing factors with a single readout line using the frequency-domain readout. We have developed abosrption-type and transmission-type MKIDs whose resonators are formed with either coplanar waveguides (CPW) or microstrips. The quality factor of the CPW MKID made of Nb is measured to be about 10 5 . The microstrip MKID is being developed for the multichroic measurements.

InS/Ntransition type Superconductingfault current limiter (SFCL),S/Ntransition process affects theburnout and the generated resistance during limiting operation. Thus, it is important to clarify the detail ofS/Ntransition process. In this study, resistive type SFCL by use of YBCO thin film is focused, and temperature distribution on YBCO thin film is measured duringS/Ntransition. RuO2 chip resistors are used as the thermal sensors. The temperature is measured on 30 points, and heat generation process is observed with the temperature distribution. In addition, the potential distribution on thin filmis measuredin same condition as temperature measurement.Temperature distributionis compared with the potential distribution to examine the accuracyof the temperature measurement results.

We have developed an Electron-Tracking Compton Camera (ETCC) for medical imaging and MeV gamma-ray astronomy. The ETCC consists of a gaseous Time Projection Chamber ( μ -TPC) and pixel scintillator arrays. To improve the detection efficiency, we have optimized the gas mixture in the μ -TPC and operated the ETCC at high pressure. Basic characteristics such as the gas gain, drift velocity, energy resolution, and position resolution of the μ -TPC were examined, and using this optimization, both the efficiency and the angular resolution of the ETCC were measured. We achieved a steady gas gain of ∼ 20 , 000 in Ar/CF4/isoC4H10 (54:40:6) at 1.4 atm. The diffusion constant in Ar/CF4/isoC4H10 (54:40:6) at 1.4 atm was ∼ 2 times better than in Ar/C2H6 (90:10) at 1 atm. The efficiency in Ar/CF4/isoC4H10 (54:40:6) at 1.4 atm was also ∼ 2 times higher than in Ar/C2H6 (90:10) at 1 atm.

We have evaluated the possibility of the Electron-Tracking Compton Camera (ETCC) to simultaneously operate as a pair-creation camera. The ETCC consists of a gaseous micro-time projection chamber (micro-TPC) and a scintillation camera. Several prototypes of the camera were developed and their performance was studied. Because the micro-TPC can detect a large number of hit points along one charged particle track, has a good position resolution of about 0.2 mm, and uses the filling gas as the scattering material, the influence of multiple scattering is small. This makes the micro-TPC well-suited to detecting pair-creation events. We have examined the performance of a camera of size 10×10×15 cm3, using the pair-creation mode in the energy range of 10–100 MeV. Using this camera, we performed a proof-of-principle experiment with laser inverse Compton gamma rays at the National Institute of Advanced Industrial Science and Technology (AIST), and we succeeded in tracking electron–positron pairs and in reconstructing 10 and 20 MeV gamma rays. In this paper, we report the fundamental performance of the gamma-ray camera with pair-creation mode.

We have developed a LaBr3:Ce scintillator array consisting of 8 × 8 pixels with a size of 5.8 mm×5.8 mm×15.0 mm, which serves as an absorber of scattered gamma rays with energies from 0.1 to 1 MeV in a Compton camera. The pixels were cut from two pieces of LaBr3:Ce crystal with a diameter of 38 mm and a length of 38 mm with full width at half-maximum (FWHM) energy resolutions of 4.1 ± 0.1% and 3.0 ± 0.1% at 356 and 662 keV, respectively, measured with a single anode photomultiplier tube (PMT). The crystal had the following volumetric uniformities: light outputs with a difference of 0.5% (standard deviation: SD) and energy resolutions with that of 2% (SD) at 356 keV. In contrast, for each pixel in the array, the average and SD FWHM energy resolutions over 64 pixels, measured with a single-anode PMT and a collimator, were 5.8 ± 0.9% at 356 keV. The array was then coupled to a 64-channel multi-anode PMT (Hamamatsu H8500), the anode pitch of which was the same as the LaBr3:Ce pixel pitch of 6.1 mm. When the 64 anodes were read out from four channels in a resistor chain by the charge division method, the FWHM energy resolution of all 64 pixels was 7.0 ± 0.5% at 662 keV, whereas that of the inner 6×6 pixels was 5.8 ± 0.4% at 662 keV. In addition, we measured a Gd2SiO5:Ce (GSO:Ce) scintillator array consisting of 8×8 pixels with a size of 5.9 mm×5.9 mm×13.0 mm to compare its performance with that of the LaBr3:Ce array. The FWHM energy resolution of all 64 GSO:Ce pixels was 10.8 ± 0.3% at 662 keV. With these energy resolutions, FWHM angular resolutions of the Compton camera using the LaBr3:Ce and GSO:Ce arrays are expected to be 4.6° and 5.3°, respectively, at 662 keV.

NEWAGE-0.3a is a prototype direction-sensitive dark matter search detector. We measured its response to electron tracks and nuclear tracks while focusing on the tracking performances in an underground laboratory. It showed a gamma-ray rejection power of 8.1 ± 1.9 × 10 −6 at 100 keV α.e.(alpha-equivalent) and an energy resolutions of 45% at 6 MeV α.e. The absolute nuclear efficiency was 80% at 100 keV α.e. and the nuclear directional-dependent efficiency was also measured. The three-dimensional angular resolution for the nuclear track was 46 ± 3° in the energy range from 100 keV α.e. to 400 keV α.e.

As next-generation MeV gamma-ray telescope, we have developed an electron-tracking Compton camera (ETCC) that consists of a gaseous tracker and an absorber. The ETCC obtains the energy and direction of both a scattered gamma ray and a recoil electron, and determines both the energy and direction of an incident gamma ray, photon by photon. Furthermore, this camera features powerful background rejection based on Compton-scattering kinematics. To prepare for future spacecraft loading, we planned the balloon experiment, “Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment” (SMILE). As the first step in SMILE, we demonstrated gamma-ray detection using our camera by observing diffuse cosmic gamma rays and secondary gamma rays generated by collisions between high-energy cosmic rays and nuclei in the air. On September 1, 2006, our detector was loaded on a balloon and launched from Sanriku Balloon Center, ISAS/JAXA. The balloon realized level flight at an altitude of about 35 km during a live time of 3.0 h. We ...

We have studied the performance of a readout system with ASIC chips for a gamma-ray camera based on a 64-channel multi-anode PSPMT (Hamamatsu flat-panel H8500) coupled to a GSO(Ce) scintillator array. The GSO array consists of 8×8 pixels of 6×6×13 mm 3 with the same pixel pitch as the anode of the H8500. This camera is intended to serve as an absorber of an electron tracking Compton gamma-ray camera that measures gamma rays up to ∼1 MeV. Because we need a readout system with low power consumption for a balloon-borne experiment, we adopted a 32-channel ASIC chip, IDEAS VA32_HDR11, which has one of the widest dynamic range among commercial chips. However, in the case of using a GSO(Ce) crystal and the H8500, the dynamic range of VA32_HDR11 is narrow, and therefore the H8500 has to be operated with a low gain of about 10 5 . If the H8500 is operated with a low gain, the camera has a narrow incident-energy dynamic range from 100 to 700 keV, and a bad energy resolution of 13.0% (FWHM) at 662 keV. We have therefore developed an attenuator board in order to operate the H8500 with the typical gain of 10 6 , which can measure up to ∼1 MeV gamma ray. The board makes the variation of the anode gain uniform and widens the dynamic range of the H8500. The system using the new attenuator board has a good uniformity of min:max∼1:1.6, an incident-energy dynamic range from 30 to 900 keV, a position resolution of less than 6 mm, and a typical energy resolution of 10.6% (FWHM) at 662 keV with a low power consumption of about 1.7 W/64ch.

We report on the development of a large Compton camera with the full reconstruction of the Compton process based on a prototype. This camera consists of two kinds of detectors. One is a gaseous time projection chamber (micro-TPC) for measuring the energy and the track of a Compton recoil electron. The micro-TPC is based on a μ -PIC and a GEM, which are micro-pattern gas detectors (MPGDs). The size of the micro-TPC was 10 cm × 10 cm × 8 cm in the case of the prototype, and we enlarged it to 23 cm × 28 cm × 15 cm . The other detector part is a NaI (Tl) Anger camera for measuring the scattered gamma-ray. With these informations, we can completely reconstruct a Compton event, and determine the direction of the incident gamma-ray, event by event. We succeeded in reconstructing events of incident 662 keV gamma-rays. The measured angular resolutions of the “angular resolution measure” (ARM) and the “scatter plane deviation” (SPD) were 9 . 3 ∘ and 158 ∘ (FWHM), respectively.

We have developed the Electron Tracking Compton Camera (ETCC) with reconstructing the 3-D tracks of the scattered electron in Compton process for both sub-MeV and MeV gamma rays. By measuring both the directions and energies of not only the recoil gamma ray but also the scattered electron, the direction of the incident gamma ray is determined for each individual photon. Furthermore, a residual measured angle between the recoil electron and scattered gamma ray is quite powerful for the kinematical background rejection. For the 3-D tracking of the electrons, the Micro Time Projection Chamber (μ-TPC) was developed using a new type of the micro pattern gas detector. The ETCC consists of this μ-TPC (10×10×8 cm3) and the 6×6×13 mm3 GSO crystal pixel arrays with a flat panel photo-multiplier surrounding the μ-TPC for detecting recoil gamma rays. The ETCC provided the angular resolution of 6.6° (FWHM) at 364 keV of 131I. A mobile ETCC for medical imaging, which is fabricated in a 1 m cubic box, has been operated since October 2005. Here, we present the imaging results for the line sources and the phantom of human thyroid gland using 364 keV gamma rays of 131I.

We have measured the OH-stretching fundamental and overtone spectra of resorcinol and hydroquinone in a supersonic jet using nonresonant ionization detected infrared/near-infrared spectroscopy. Anharmonic oscillator local mode calculations of the OH-stretching frequencies and intensities and Boltzmann populations of the stable rotamers have been calculated at the B3LYP/6-311++G(3df,2pd) level to help interpret the observed spectra. Resorcinol has three stable rotamers and in the recorded second and third OH-stretching overtone spectra there is evidence of two distinguishable rotamers. Hydroquinone has two stable rotamers; however, the OH-stretching oscillators of each rotamer are so similar in nature that even up to the fourth OH-stretching overtone the transitions coincide. These results place a limit on the ability of the jet-cooled overtone spectroscopy technique to distinguish between rotamers.

A Micro Pixel Chamber, called “ μ -PIC”, is a gaseous 2D imaging detector with a fine pixel electrode based on the Printed Circuit Board technology, and we developed it for the X/gamma-ray imaging and the tracking of the charged particles [A. Ochi, et al., Nucl. Instr. and Meth. A 478 (2002) 196; T. Nagayoshi, et al., Nucl. Instr. and Meth. A 525 (2004) 20.]. The previous μ -PIC has a fine position resolution, a high gas gain, a good gas gain uniformity and the stable operation. Although the detection area of the previous μ -PIC ( ∼ 10 × 10 cm 2 ) is not large enough for a variety of the application, for example an MeV gamma-ray Compton camera [T. Tanimori, et al., New Astron. Rev. 48 (2004) 263.] and dark matter search [T. Tanimori, et al., Phys. Lett. B 578 (2004) 241.]. Therefore, we developed a new μ -PIC having a ∼ 30 × 30 cm 2 detection area. The structure and the pitch of the electrode are same as those of the previous μ -PIC. There are 768 × 768 pixels in the whole area. This μ -PIC (TOSHIBA SN041129-1) is operated with a stable gas gain of ∼ 3500 and a maximum gain of ∼ 7000 at the center region, and the variety of the gain was 16.7% RMS. An X-ray image of the whole area was also taken by the irradiation of the X-rays from 109Cd (22 keV) to the whole detection area.

Phenol + –Kr cations (PhOH + –Kr) generated by photoionization (REMPI) of the neutral complex and in an electron ionization (EI) source were assayed by their infrared (IR) spectra in the OH stretch ( ν OH ) range. Two isomers are identified in the EI–IR spectrum by their Δ ν OH complexation shifts: the more stable H-bound global minimum (Δ ν OH = −123 cm −1 ) and the less stable π-bound local minimum (Δ ν OH = +1 cm −1 ). The REMPI–IR spectrum reveals ν OH absorptions assigned to cold π-bound complexes and hot H-bound dimers. The latter are generated via π → H isomerization after the ionization of neutral π-bound dimers. EI–IR spectra are also presented for PhOH + –Kr 2 . Quantum chemical calculations support the interpretation of the spectroscopic data.

Atmosphere is one of the most important noise sources for ground-based cosmic microwave background (CMB) experiments. By increasing optical loading on the detectors, it amplifies their effective noise, while its fluctuations introduce spatial and temporal correlations between detected signals. We present a physically motivated 3d-model of the atmosphere total intensity emission in the millimeter and sub-millimeter wavelengths. We derive a new analytical estimate for the correlation between detectors time-ordered data as a function of the instrument and survey design, as well as several atmospheric parameters such as wind, relative humidity, temperature and turbulence characteristics. Using an original numerical computation, we examine the effect of each physical parameter on the correlations in the time series of a given experiment. We then use a parametric-likelihood approach to validate the modeling and estimate atmosphere parameters from the POLARBEAR-I project first season data set. We derive a new 1.0% upper limit on the linear polarization fraction of atmospheric emission. We also compare our results to previous studies and weather station measurements. The proposed model can be used for realistic simulations of future ground-based CMB observations., Comment: 20 pages, 16 figures