A method to stabilize the temperature dependent performance of G-APD arrays

Energy Technology Data Exchange (ETDEWEB)

Huh, Yoonsuk [Molecular Imaging Research and Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of); Sungkyunkwan University, School of Medicine, Seoul (Korea, Republic of); Choi, Yong; Ho Jung, Jin; Jung, Jiwoong [Molecular Imaging Research and Education (MiRe) Laboratory, Department of Electronic Engineering, Sogang University, Seoul (Korea, Republic of)

2015-02-01

This paper presents a compensation method to stabilize the temperature dependent performance of Geiger-mode Avalanche Photodiode (G-APD) arrays for Positron Emission Tomography (PET). The compensation method is used to identify the bias voltage range that provides stable performance even at different temperatures using the G-APD’s characteristics, and to control the photo-peak variation as a function of temperature using the preamplifier gain within the identified bias voltage range. A pair of G-APD detectors and temperature sensors were located in the temperature chamber and the preamplifiers which can control the gain of the detectors using the digital potentiometer were positioned outside the chamber. The performance of the G-APD detector, especially energy resolution and coincidence timing resolution, was characterized as a function of bias voltage at different temperatures from 20 °C to 40 °C at 5 °C increments; the energy resolution, coincidence timing resolution, and photo-peak position of all channels of G-APD PET detectors before and after the preamplifier gain correction were then measured and compared. The results of this study demonstrated that the optimal bias voltage range providing the good energy and coincidence timing resolution, 12.1±1.2% and 1.30±0.09 ns, respectively, could be identified at the temperature range and the photo-peak variation and the performance at different temperatures could be stabilized by adjusting the preamplifier gain within the identified bias voltage range. We concluded the proposed method to be reliable and useful for the development of the PET system using G-APD arrays.

FACT - Status and experience from five years of operation of the first G-APD Cherenkov Telescope

Science.gov (United States)

Neise, D.; Adam, J.; Ahnen, M. L.; Baack, D.; Balbo, M.; Bergmann, M.; Biland, A.; Blank, M.; Bretz, T.; Brügge, K. A.; Buss, J.; Dmytriiev, A.; Dorner, D.; Einecke, S.; Hempfling, C.; Hildebrand, D.; Hughes, G.; Linhoff, L.; Mannheim, K.; Müller, S.; Neronov, A.; Nöthe, M.; Paravac, A.; Pauss, F.; Rhode, W.; Shukla, A.; Temme, F.; Thaele, J.; Walter, R.

2017-12-01

The First G-APD Cherenkov Telescope (FACT) demonstrates the usability of novel Geiger-mode operated Avalanche Photo Diodes (G-APD, often called SiPM) for Imaging Atmospheric Cherenkov Telescopes (IACT). The camera consists of 1440 pixels with dedicated electronics operating at 2 Giga samples per second. It is installed on the refurbished HEGRA telescope with a mirror area of ≈ 9.5m2 on the Canary Island La Palma. FACT is taking data almost every night since the camera was installed in October 2011. It was possible to improve the data taking efficiency to very high values due to the very stable and reliable operation. This also allows to operate FACT remotely without any need for operators on site. Even remote human intervention became less and less frequent over the years, allowing operation to become mostly automatic. FACT is monitoring the long-term behavior of some very-high energy variable extra-galactic sources with unparalleled sampling density as well as testing the behavior of the sensors under severe weather conditions. Due to the long exposure of FACT's G-APDs under strong moonlight conditions it was possible to evaluate the aging effects of G-APDs due to collected charge. No indication of aging was found. No external calibration device is needed to operate FACT since the properties of the sensors themselves allow for a high precision self-calibration of the camera.

Application of Geiger-mode photosensors in Cherenkov detectors

Energy Technology Data Exchange (ETDEWEB)

Gamal, Ahmed, E-mail: gamal.ahmed@assoc.oeaw.ac.a [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria); Al-Azhar University, Faculty of Science, Physics Department, Cairo (Egypt); Paul, Buehler; Michael, Cargnelli [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria); Roland, Hohler [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Johann, Marton [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria); Herbert, Orth [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); Ken, Suzuki [Stefan Meyer Institute for Subatomic Physics of the Austrian Academy of Sciences, Vienna (Austria)

2011-05-21

Silicon-based photosensors (SiPMs) working in the Geiger-mode represent an elegant solution for the readout of particle detectors working at low-light levels like Cherenkov detectors. Especially the insensitivity to magnetic fields makes this kind of sensors suitable for modern detector systems in subatomic physics which are usually employing magnets for momentum resolution. We are characterizing SiPMs of different manufacturers for selecting sensors and finding optimum operating conditions for given applications. Recently we designed and built a light concentrator prototype with 8x8 cells to increase the active photon detection area of an 8x8 SiPM (Hamamatsu MPPC S10931-100P) array. Monte Carlo studies, measurements of the collection efficiency, and tests with the MPPC were carried out. The status of these developments are presented.

AX-PET: A novel PET concept with G-APD readout

CERN Document Server

Heller, M; Casella, C; Chesi, E; De Leo, R; Dissertori, G; Fanti, V; Gillam, J E; Joram, C; Lustermann, W; Nappi, E; Oliver, J F; Pauss, F; Rafecas, M; Rudge, A; Ruotsalainen, U; Schinzel, D; Schneider, T; Seguinot, J; Solevi, P; Stapnes, S; Tuna, U; Weilhammer, P

2012-01-01

The AX-PET collaboration has developed a novel concept for high resolution PET imaging to overcome some of the performance limitations of classical PET cameras, in particular the compromise between spatial resolution and sensitivity introduced by the parallax error. The detector consists of an arrangement of long LYSO scintillating crystals axially oriented around the field of view together with arrays of wave length shifter strips orthogonal to the crystals. This matrix allows a precise 3D measurement of the photon interaction point. This is valid both for photoelectric absorption at 511 key and for Compton scattering down to deposited energies of about 100 keV. Crystals and WLS strips are individually read out using Geiger-mode Avalanche Photo Diodes (G-APDs). The sensitivity of such a detector can be adjusted by changing the number of layers and the resolution is defined by the crystal and strip dimensions. Two AX-PET modules were built and fully characterized in dedicated test set-ups at CERN, with point-...

Single-Photon-Sensitive HgCdTe Avalanche Photodiode Detector

Science.gov (United States)

Huntington, Andrew

2013-01-01

The purpose of this program was to develop single-photon-sensitive short-wavelength infrared (SWIR) and mid-wavelength infrared (MWIR) avalanche photodiode (APD) receivers based on linear-mode HgCdTe APDs, for application by NASA in light detection and ranging (lidar) sensors. Linear-mode photon-counting APDs are desired for lidar because they have a shorter pixel dead time than Geiger APDs, and can detect sequential pulse returns from multiple objects that are closely spaced in range. Linear-mode APDs can also measure photon number, which Geiger APDs cannot, adding an extra dimension to lidar scene data for multi-photon returns. High-gain APDs with low multiplication noise are required for efficient linear-mode detection of single photons because of APD gain statistics -- a low-excess-noise APD will generate detectible current pulses from single photon input at a much higher rate of occurrence than will a noisy APD operated at the same average gain. MWIR and LWIR electron-avalanche HgCdTe APDs have been shown to operate in linear mode at high average avalanche gain (M > 1000) without excess multiplication noise (F = 1), and are therefore very good candidates for linear-mode photon counting. However, detectors fashioned from these narrow-bandgap alloys require aggressive cooling to control thermal dark current. Wider-bandgap SWIR HgCdTe APDs were investigated in this program as a strategy to reduce detector cooling requirements.

Design and performance of single photon APD focal plane arrays for 3-D LADAR imaging

Science.gov (United States)

Itzler, Mark A.; Entwistle, Mark; Owens, Mark; Patel, Ketan; Jiang, Xudong; Slomkowski, Krystyna; Rangwala, Sabbir; Zalud, Peter F.; Senko, Tom; Tower, John; Ferraro, Joseph

2010-08-01

×We describe the design, fabrication, and performance of focal plane arrays (FPAs) for use in 3-D LADAR imaging applications requiring single photon sensitivity. These 32 × 32 FPAs provide high-efficiency single photon sensitivity for three-dimensional LADAR imaging applications at 1064 nm. Our GmAPD arrays are designed using a planarpassivated avalanche photodiode device platform with buried p-n junctions that has demonstrated excellent performance uniformity, operational stability, and long-term reliability. The core of the FPA is a chip stack formed by hybridizing the GmAPD photodiode array to a custom CMOS read-out integrated circuit (ROIC) and attaching a precision-aligned GaP microlens array (MLA) to the back-illuminated detector array. Each ROIC pixel includes an active quenching circuit governing Geiger-mode operation of the corresponding avalanche photodiode pixel as well as a pseudo-random counter to capture per-pixel time-of-flight timestamps in each frame. The FPA has been designed to operate at frame rates as high as 186 kHz for 2 μs range gates. Effective single photon detection efficiencies as high as 40% (including all optical transmission and MLA losses) are achieved for dark count rates below 20 kHz. For these planar-geometry diffused-junction GmAPDs, isolation trenches are used to reduce crosstalk due to hot carrier luminescence effects during avalanche events, and we present details of the crosstalk performance for different operating conditions. Direct measurement of temporal probability distribution functions due to cumulative timing uncertainties of the GmAPDs and ROIC circuitry has demonstrated a FWHM timing jitter as low as 265 ps (standard deviation is ~100 ps).

Progress in low light-level InAs detectors- towards Geiger-mode detection

Science.gov (United States)

Tan, Chee Hing; Ng, Jo Shien; Zhou, Xinxin; David, John; Zhang, Shiyong; Krysa, Andrey

2017-05-01

InAs avalanche photodiodes (APDs) can be designed such that only electrons are allowed to initiate impact ionization, leading to the lowest possible excess noise factor. Optimization of wet chemical etching and surface passivation produced mesa APDs with bulk dominated dark current and responsivity that are comparable and higher, respectively, than a commercial InAs detector. Our InAs electron-APDs also show high stability with fluctuation of 0.1% when operated at a gain of 11.2 over 60 s. These InAs APDs can detect very weak signal down to 35 photons per pulse. Fabrication of planar InAs by Be implantation produced planar APDs with bulk dominated dark current. Annealing at 550 °C was necessary to remove implantation damage and to activate Be dopants. Due to minimal diffusion of Be, thick depletion of 8 μm was achieved. Since the avalanche gain increases exponentially with the thickness of avalanche region, our planar APD achieved high gain > 300 at 200 K. Our work suggest that both mesa and planar InAs APDs can exhibit high gain. When combined with a suitable preamplifier, single photon detection using InAs electron-APDs could be achieved.

Multipixel geiger-mode photon detectors for ultra-weak light sources

International Nuclear Information System (INIS)

Campisi, A.; Cosentino, L.; Finocchiaro, P.; Pappalardo, A.; Musumeci, F.; Privitera, S.; Scordino, A.; Tudisco, S.; Fallica, G.; Sanfilippo, D.; Mazzillo, M.; Condorelli, G.; Piazza, A.; Valvo, G.; Lombardo, S.; Sciacca, E.; Bonanno, G.; Belluso, M.

2007-01-01

Arrays of Single Photon Avalanche Detectors (SPAD) are considered today as a possible alternative to PMTs and other semiconductor devices in several applications, like physics research, bioluminescence, Positron Emission Tomography (PET) systems, etc. We have developed and characterized a first prototype array produced by STMicroelectronics in silicon planar technology and working at low voltage (30-40 V) in Geiger mode operation. The single cell structure (size down to 20 μm) and the geometrical arrangement give rise to appealing intrinsic characteristics of the device, such as photon detection efficiency, dark count map, cross-talk effects, timing and energy resolution. New prototypes are under construction with a higher number of pixels that have a common output signal to obtain a so-called SiPM (Silicon PhotoMultiplier) configuration

A discrete model of the development and relaxation of a local microbreakdown in silicon avalanche photodiodes operating in the Geiger mode

International Nuclear Information System (INIS)

Vanyushin, I. V.; Gergel, V. A.; Gontar', V. M.; Zimoglyad, V. A.; Tishin, Yu. I.; Kholodnov, V. A.; Shcheleva, I. M.

2007-01-01

A new discrete theoretical model of the development and relaxation of a local microbreakdown in silicon avalanche photodiodes operating in the Geiger mode is developed. It is shown that the spreading resistance in the substrate profoundly affects both the amplitude of a single-photon electrical pulse and the possibility of attaining the steady-state form of the avalanche breakdown excluding the Geiger mode of the photodiode's operation. The model is employed to interpret the experimental data obtained using test single-photon cells of avalanche photodiodes fabricated on the basis of the 0.25-μm silicon technology with the use of deep implantation to form the region of avalanche multiplication for the charge carriers. Excellent functional properties of the studied type of the single-photon (Geiger) cell are noted. A typical amplitude characteristic of the cell for optical radiation with the wavelength λ = 0.56 μm in the irradiance range of 10 -3 -10 2 lx is presented; this characteristic indicates that the quantum efficiency of photoconversion is extremely high

Generation efficiency of single-photon current pulses in the Geiger mode of silicon avalanche photodiodes

International Nuclear Information System (INIS)

Verkhovtseva, A. V.; Gergel, V. A.

2009-01-01

Statistical fluctuations of the avalanche's multiplication efficiency were studied as applied to the single-photon (Geiger) mode of avalanche photodiodes. The distribution function of partial multiplication factors with an anomalously wide (of the order of the average) dispersion was obtained. Expressions for partial feedback factors were derived in terms of the average gain and the corresponding dependences on the diode's overvoltage were calculated. Final expressions for the photon-electric pulse's conversion were derived by averaging corresponding formulas over the coordinate of initiating photoelectron generation using the functions of optical photon absorption in silicon.

Evaluation of single photon and Geiger mode Lidar for the 3D Elevation Program

Science.gov (United States)

Stoker, Jason M.; Abdullah, Qassim; Nayegandhi, Amar; Winehouse, Jayna

2016-01-01

Data acquired by Harris Corporation’s (Melbourne, FL, USA) Geiger-mode IntelliEarth™ sensor and Sigma Space Corporation’s (Lanham-Seabrook, MD, USA) Single Photon HRQLS sensor were evaluated and compared to accepted 3D Elevation Program (3DEP) data and survey ground control to assess the suitability of these new technologies for the 3DEP. While not able to collect data currently to meet USGS lidar base specification, this is partially due to the fact that the specification was written for linear-mode systems specifically. With little effort on part of the manufacturers of the new lidar systems and the USGS Lidar specifications team, data from these systems could soon serve the 3DEP program and its users. Many of the shortcomings noted in this study have been reported to have been corrected or improved upon in the next generation sensors.

Radiation damage of multipixel Geiger-mode avalanche photodiodes irradiated with low-energy γ's and electrons

Energy Technology Data Exchange (ETDEWEB)

Kwon, Y.; Yun, Y. B. [Yonsei University, Seoul (Korea, Republic of); Ha, J. M. [Yonsei University, Seoul (Korea, Republic of); Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of); Lee, J. S.; Yoon, Y. S. [Electronics and Telecommunications Research Institute, Daejeon (Korea, Republic of); Eun, J. W. [Namseoul University, Cheonan (Korea, Republic of)

2012-05-15

A few types of multipipixel Geiger-mode avalanche photodiodes (also referred to as silicon photomultipliers SiPMs) are irradiated with 1 to 2.5 MeV γ's and electrons. We characterize radiation damage effects appearing in the reverse bias current, the dark current and count rate, the pixel gain, and the photon detection efficiency of the devices. An interesting observation on the dark current and count rate is made and linked to the specific damage caused by the irradiation.

Linear LIDAR versus Geiger-mode LIDAR: impact on data properties and data quality

Science.gov (United States)

Ullrich, A.; Pfennigbauer, M.

2016-05-01

LIDAR has become the inevitable technology to provide accurate 3D data fast and reliably even in adverse measurement situations and harsh environments. It provides highly accurate point clouds with a significant number of additional valuable attributes per point. LIDAR systems based on Geiger-mode avalanche photo diode arrays, also called single photon avalanche photo diode arrays, earlier employed for military applications, now seek to enter the commercial market of 3D data acquisition, advertising higher point acquisition speeds from longer ranges compared to conventional techniques. Publications pointing out the advantages of these new systems refer to the other category of LIDAR as "linear LIDAR", as the prime receiver element for detecting the laser echo pulses - avalanche photo diodes - are used in a linear mode of operation. We analyze the differences between the two LIDAR technologies and the fundamental differences in the data they provide. The limitations imposed by physics on both approaches to LIDAR are also addressed and advantages of linear LIDAR over the photon counting approach are discussed.

The performance of photon counting imaging with a Geiger mode silicon avalanche photodiode

International Nuclear Information System (INIS)

Qu, Hui-Ming; Zhang, Yi-Fan; Ji, Zhong-Jie; Chen, Qian

2013-01-01

In principle, photon counting imaging can detect a photon. With the development of low-level-light image intensifier techniques and low-level-light detection devices, photon counting imaging can now detect photon images under extremely low illumination. Based on a Geiger mode silicon avalanche photodiode single photon counter, an experimental system for photon counting imaging was built through two-dimensional scanning of a SPAD (single photon avalanche diode) detector. The feasibility of the imaging platform was validated experimentally. Two images with different characteristics, namely, the USAF 1951 resolution test panel and the image of Lena, were chosen to evaluate the imaging performance of the experimental system. The results were compared and analysed. The imaging properties under various illumination and scanning steps were studied. The lowest illumination limit of the SPAD photon counting imaging was determined. (letter)

Design and implementation of Gm-APD array readout integrated circuit for infrared 3D imaging

Science.gov (United States)

Zheng, Li-xia; Yang, Jun-hao; Liu, Zhao; Dong, Huai-peng; Wu, Jin; Sun, Wei-feng

2013-09-01

A single-photon detecting array of readout integrated circuit (ROIC) capable of infrared 3D imaging by photon detection and time-of-flight measurement is presented in this paper. The InGaAs avalanche photon diodes (APD) dynamic biased under Geiger operation mode by gate controlled active quenching circuit (AQC) are used here. The time-of-flight is accurately measured by a high accurate time-to-digital converter (TDC) integrated in the ROIC. For 3D imaging, frame rate controlling technique is utilized to the pixel's detection, so that the APD related to each pixel should be controlled by individual AQC to sense and quench the avalanche current, providing a digital CMOS-compatible voltage pulse. After each first sense, the detector is reset to wait for next frame operation. We employ counters of a two-segmental coarse-fine architecture, where the coarse conversion is achieved by a 10-bit pseudo-random linear feedback shift register (LFSR) in each pixel and a 3-bit fine conversion is realized by a ring delay line shared by all pixels. The reference clock driving the LFSR counter can be generated within the ring delay line Oscillator or provided by an external clock source. The circuit is designed and implemented by CSMC 0.5μm standard CMOS technology and the total chip area is around 2mm×2mm for 8×8 format ROIC with 150μm pixel pitch. The simulation results indicate that the relative time resolution of the proposed ROIC can achieve less than 1ns, and the preliminary test results show that the circuit function is correct.

APD arrays and large-area APDs via a new planar process

CERN Document Server

Farrell, R; Vanderpuye, K; Grazioso, R; Myers, R; Entine, G

2000-01-01

A fabrication process has been developed which allows the beveled-edge-type of avalanche photodiode (APD) to be made without the need for the artful bevel formation steps. This new process, applicable to both APD arrays and to discrete detectors, greatly simplifies manufacture and should lead to significant cost reduction for such photodetectors. This is achieved through a simple innovation that allows isolation around the device or array pixel to be brought into the plane of the surface of the silicon wafer, hence a planar process. A description of the new process is presented along with performance data for a variety of APD device and array configurations. APD array pixel gains in excess of 10 000 have been measured. Array pixel coincidence timing resolution of less than 5 ns has been demonstrated. An energy resolution of 6% for 662 keV gamma-rays using a CsI(T1) scintillator on a planar processed large-area APD has been recorded. Discrete APDs with active areas up to 13 cm sup 2 have been operated.

Geiger-mueller radiation detector with means for detecting and indicating the existence of radiation overload

International Nuclear Information System (INIS)

Kovacs, T.; Mills, A.P.; Pfeiffer, L.N.

1981-01-01

When subjected to radiation overload existing geiger-mueller counters may give an erroneously low reading, resulting in possible hazard to personnel. The instant invention discloses simple and inexpensive apparatus to remedy this dangerous shortcoming. Depending on the geometry of the detector tube, two possible failure modes have been identified, and circuitry is disclosed to detect the existence of these respective failure modes. The disclosed apparatus indicates the absence of an overload condition, in addition to signaling, by both visible and audible means, the existence of excessive radiation that might result in erroneously low reading of the geiger-mueller counter

A method to quench and recharge avalanche photo diodes for use in high rate situations

International Nuclear Information System (INIS)

Regan, T.O.; Fenker, H.C.; Thomas, J.; Oliver, J.

1992-06-01

We present a new method of using Avalanche Photo Diodes (APDS) for low level light detection in Geiger mode in high rate situations such as those encountered at the Superconducting Super Collider (SSC). The new technique is readily adaptable to implementation in CMOS VLSI

Hybrid AlGaN-SiC Avalanche Photodiode for Deep-UV Photon Detection

Science.gov (United States)

Aslam, Shahid; Herrero, Federico A.; Sigwarth, John; Goldsman, Neil; Akturk, Akin

2010-01-01

The proposed device is capable of counting ultraviolet (UV) photons, is compatible for inclusion into space instruments, and has applications as deep- UV detectors for calibration systems, curing systems, and crack detection. The device is based on a Separate Absorption and Charge Multiplication (SACM) structure. It is based on aluminum gallium nitride (AlGaN) absorber on a silicon carbide APD (avalanche photodiode). The AlGaN layer absorbs incident UV photons and injects photogenerated carriers into an underlying SiC APD that is operated in Geiger mode and provides current multiplication via avalanche breakdown. The solid-state detector is capable of sensing 100-to-365-nanometer wavelength radiation at a flux level as low as 6 photons/pixel/s. Advantages include, visible-light blindness, operation in harsh environments (e.g., high temperatures), deep-UV detection response, high gain, and Geiger mode operation at low voltage. Furthermore, the device can also be designed in array formats, e.g., linear arrays or 2D arrays (micropixels inside a superpixel).

Single ion implantation for single donor devices using Geiger mode detectors

International Nuclear Information System (INIS)

Bielejec, E; Seamons, J A; Carroll, M S

2010-01-01

Electronic devices that are designed to use the properties of single atoms such as donors or defects have become a reality with recent demonstrations of donor spectroscopy, single photon emission sources, and magnetic imaging using defect centers in diamond. Ion implantation, an industry standard for atom placement in materials, requires augmentation for single ion capability including a method for detecting a single ion arrival. Integrating single ion detection techniques with the single donor device construction region allows single ion arrival to be assured. Improving detector sensitivity is linked to improving control over the straggle of the ion as well as providing more flexibility in lay-out integration with the active region of the single donor device construction zone by allowing ion sensing at potentially greater distances. Using a remotely located passively gated single ion Geiger mode avalanche diode (SIGMA) detector we have demonstrated 100% detection efficiency at a distance of >75 μm from the center of the collecting junction. This detection efficiency is achieved with sensitivity to ∼600 or fewer electron-hole pairs produced by the implanted ion. Ion detectors with this sensitivity and integrated with a thin dielectric, for example a 5 nm gate oxide, using low energy Sb implantation would have an end of range straggle of -1 and 10 -4 for operation temperatures of ∼300 K and ∼77 K, respectively. Low temperature operation and reduced false, 'dark', counts are critical to achieving high confidence in single ion arrival. For the device performance in this work, the confidence is calculated as a probability of >98% for counting one and only one ion for a false count probability of 10 -4 at an average ion number per gated window of 0.015.

Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding

Energy Technology Data Exchange (ETDEWEB)

Kolb, A., E-mail: armin.kolb@med.uni-tuebingen.de; Parl, C.; Liu, C. C.; Pichler, B. J. [Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, 72076 Tübingen (Germany); Mantlik, F. [Werner Siemens Imaging Center, Department of Preclinical Imaging and Radiopharmacy, Eberhard Karls University, 72076 Tübingen, Germany and Department of Empirical Inference, Max Planck Institute for Intelligent Systems, 72076 Tübingen (Germany); Lorenz, E. [Max Planck Institute for Physics, Föhringer Ring 6, 80805 München (Germany); Renker, D. [Department of Physics, Technische Universität München, 85748 Garching (Germany)

2014-08-15

Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, these small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated {sup 18}F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 �

An Inexpensive Coincidence Circuit for the Pasco Geiger Sensors

CERN Document Server

Fichera, F; Librizzi, F; Riggi, F

2005-01-01

A simple coincidence circuit was devised to carry out educational coincidence experiments involving the use of Geiger counters. The system was tested by commercially available Geiger sensors from PASCO, and is intended to be used in collaboration with high school students and teachers

Testing limits to airflow perturbation device (APD measurements

Directory of Open Access Journals (Sweden)

Jamshidi Shaya

2008-10-01

Full Text Available Abstract Background The Airflow Perturbation Device (APD is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated. Method Ten subjects between the ages of 18 and 35 were tested for each station in the experiment. The first station involved testing the effects of leaks of known sizes on APD measurements. The second station tested the use of an oronasal mask used in conjunction with the APD during nose and mouth breathing. The third station tested the effects of two different resistances added in series with the APD mouthpiece. The fourth station tested the usage of a flexible ventilator tube in conjunction with the APD. Results All leaks reduced APD resistance measurement values. Leaks represented by two 3.2 mm diameter tubes reduced measured resistance by about 10% (4.2 cmH2O·sec/L for control and 3.9 cm H2O·sec/L for the leak. This was not statistically significant. Larger leaks given by 4.8 and 6.4 mm tubes reduced measurements significantly (3.4 and 3.0 cm cmH2O·sec/L, respectively. Mouth resistance measured with a cardboard mouthpiece gave an APD measurement of 4.2 cm H2O·sec/L and mouth resistance measured with an oronasal mask was 4.5 cm H2O·sec/L; the two were not significantly different. Nose resistance measured with the oronasal mask was 7.6 cm H2O·sec/L. Adding airflow resistances of 1.12 and 2.10 cm H2O·sec/L to the breathing circuit between the mouth and APD yielded respiratory resistance values higher than the control by 0.7 and 2.0 cm H2O·sec/L. Although breathing through a 52 cm length of flexible ventilator tubing reduced the APD

Free-running InGaAs/InP single photon detector with feedback quenching IC

International Nuclear Information System (INIS)

Zheng, Fu; Wang, Feilong; Wang, Chao; Sun, Zhibin; Zhai, Guangjie

2015-01-01

InGaAs/InP avalanche photodiodes (APD) are usually employed as Geiger-mode single photon detector at near-infrared wavelength between 1.0 μm and 1.7 μm. In order to work in the free-running regime rather than gated regime, we demonstrate a feedback quenching integrated circuit to rapidly quench the avalanche and reset the APD. Because this IC is close to the APD, parasitic capacitance is largely reduced, thus reducing the quench-time, reset-time and also the afterpulsing probability. We investigated the free-running single photon detector's afterpulsing effect, de-trapping time, dark count rate and detection efficiency and also compared with gated regime operation. After corrected for deadtime and afterpulse, we found the free-running detector performance is comparable with gated regime

A lens-coupled scintillation counter in cryogenic environment

International Nuclear Information System (INIS)

Stoykov, A; Scheuermann, R; Amato, A; Bartkowiak, M; Konter, J A; Rodriguez, J; Sedlak, K

2011-01-01

In this work we present an elegant solution for a scintillation counter to be integrated into a cryogenic system. Its distinguishing feature is the absence of a continuous light guide coupling the scintillation and the photodetector parts, operating at cryogenic and room temperatures respectively. The prototype detector consists of a plastic scintillator with glued-in wavelength-shifting fiber located inside a cryostat, a Geiger-mode Avalanche Photodiode (G-APD) outside the cryostat, and a lens system guiding the scintillation light re-emitted by the fiber to the G-APD through optical windows in the cryostat shields. With a 0.8 mm diameter multiclad fiber and a 1 mm active area G-APD the coupling efficiency of the 'lens light guide' is about 50%. A reliable performance of the detector down to 3 K is demonstrated.

A Novel Time-Based Readout Scheme for a Combined PET-CT Detector Using APDs

CERN Document Server

Powolny, F; Hillemanns, H; Jarron, P; Lecoq, P; Meyer, T C; Moraes, D

2008-01-01

This paper summarizes CERN R&D work done in the framework of the European Commission's FP6 BioCare Project. The objective was to develop a novel "time-based" signal processing technique to read out LSO-APD photodetectors for medical imaging. An important aspect was to employ the technique in a combined scenario for both computer tomography (CT) and positron emission tomography (PET) with effectively no tradeoffs in efficiency and resolution compared to traditional single mode machines. This made the use of low noise and yet very high-speed monolithic front-end electronics essential so as to assure the required timing characteristics together with a high signal-to-noise ratio. Using APDs for photon detection, two chips, traditionally employed for particle physics, could be identified to meet the above criteria. Although both were not optimized for their intended new medical application, excellent performance in conjunction with LSO-APD sensors could be derived. Whereas a measured energy resolution of 16% (...

A Highly Sensitive Multi-Element HgCdTe E-APD Detector for IPDA Lidar Applications

Science.gov (United States)

Beck, Jeff; Welch, Terry; Mitra, Pradip; Reiff, Kirk; Sun, Xiaoli; Abshire, James

2014-01-01

An HgCdTe electron avalanche photodiode (e-APD) detector has been developed for lidar receivers, one application of which is integrated path differential absorption lidar measurements of such atmospheric trace gases as CO2 and CH4. The HgCdTe APD has a wide, visible to mid-wave-infrared, spectral response, high dynamic range, substantially improved sensitivity, and an expected improvement in operational lifetime. A demonstration sensor-chip assembly consisting of a 4.3 lm cutoff HgCdTe 4 9 4 APD detector array with 80 micrometer pitch pixels and a custom complementary metal-oxide-semiconductor readout integrated circuit was developed. For one typical array the APD gain was 654 at 12 V with corresponding gain normalized dark currents ranging from 1.2 fA to 3.2 fA. The 4 9 4 detector system was characterized at 77 K with a 1.55 micrometer wavelength, 1 microsecond wide, laser pulse. The measured unit gain detector photon conversion efficiency was 91.1%. At 11 V bias the mean measured APD gain at 77 K was 307.8 with sigma/mean uniformity of 1.23%. The average, noise-bandwidth normalized, system noise-equivalent power (NEP) was 1.04 fW/Hz(exp 1/2) with a sigma/mean of 3.8%. The measured, electronics-limited, bandwidth of 6.8 MHz was more than adequate for 1 microsecond pulse detection. The system had an NEP (3 MHz) of 0.4 fW/Hz(exp 1/2) at 12 V APD bias and a linear dynamic range close to 1000. A gain-independent quantum-limited SNR of 80% of full theoretical was indicative of a gain-independent excess noise factor very close to 1.0 and the expected APD mode quantum efficiency.

As the crack in the Geiger counter came. Historical scientific analysis and didactic aspects of the Geiger-Mueller counting tube

International Nuclear Information System (INIS)

Korff, Sebastian

2014-01-01

This thesis studies the creation and establishment history of this instrument called first electron counting tube in the years 1928 and 1929. It deals thereby with the last two years of the common work of Hans Geiger and Walter Mueller, from which the measuring instrument later renamed to Geiger-Mueller counting tube. The results of this scientific case study are didactically worked out and made usable for the teaching of physics in the school.

Modelization, fabrication and evaluation avalanche photodiodes polarized in Geiger mode for the single photon in astrophysics applications

International Nuclear Information System (INIS)

Pellion, D.

2008-12-01

The genesis of the work presented in this this is in the field of very high energy astrophysics. One century ago, scientists identified a new type of messenger coming from space: cosmic rays. This radiation consists of particles (photons or other) of very high energy which bombard the Earth permanently. The passage of cosmic radiations in the Earth's atmosphere results in the creation of briefs luminous flashes (5 ns) of very low intensity (1 pW), a Cherenkov flash, and then becomes visible on the ground. In the current state of the art the best detector of light today is the Photomultiplier tube (PMT), thanks to its characteristics of sensitivity and speed. But there are some drawbacks: low quantum efficiency, cost, weight etc. We present in this thesis a new alternative technology: silicon photon counters, made of photodiodes polarized in Geiger mode. This operating mode makes it possible to obtain an effect of multiplication comparable to that of the PMT. A physical and electrical model was developed to reproduce the behaviour of this detector. We then present in this thesis work an original technological process allowing the realization of these devices in the Center of Technology of LAAS-CNRS, with the simulation of each operation of the process. We developed a scheme for the electric characterization of the device, from the static mode to the dynamic mode, in order to check conformity with SILVACO simulations and to the initial model. Results are already excellent, given this is only a first prototype step, and comparable with the results published in the literature. These silicon devices can intervene in all the applications where there is a photomultiplier and replace it. The applications are thus very numerous and the growth of the market of these detectors is very fast. We present a first astrophysical experiment installed at the 'Pic du Midi' site which has detected Cherenkov flashes from cosmic rays with this new semiconductor technology. (author)

Modelization, fabrication and evaluation avalanche photodiodes polarized in Geiger mode for the single photon in astrophysics applications; Modelisation, fabrication et evaluation des photodiodes a avalanche polarisees en mode Geiger pour la detection du photon unique dans les applications Astrophysiques

Energy Technology Data Exchange (ETDEWEB)

Pellion, D

2008-12-15

The genesis of the work presented in this this is in the field of very high energy astrophysics. One century ago, scientists identified a new type of messenger coming from space: cosmic rays. This radiation consists of particles (photons or other) of very high energy which bombard the Earth permanently. The passage of cosmic radiations in the Earth's atmosphere results in the creation of briefs luminous flashes (5 ns) of very low intensity (1 pW), a Cherenkov flash, and then becomes visible on the ground. In the current state of the art the best detector of light today is the Photomultiplier tube (PMT), thanks to its characteristics of sensitivity and speed. But there are some drawbacks: low quantum efficiency, cost, weight etc. We present in this thesis a new alternative technology: silicon photon counters, made of photodiodes polarized in Geiger mode. This operating mode makes it possible to obtain an effect of multiplication comparable to that of the PMT. A physical and electrical model was developed to reproduce the behaviour of this detector. We then present in this thesis work an original technological process allowing the realization of these devices in the Center of Technology of LAAS-CNRS, with the simulation of each operation of the process. We developed a scheme for the electric characterization of the device, from the static mode to the dynamic mode, in order to check conformity with SILVACO simulations and to the initial model. Results are already excellent, given this is only a first prototype step, and comparable with the results published in the literature. These silicon devices can intervene in all the applications where there is a photomultiplier and replace it. The applications are thus very numerous and the growth of the market of these detectors is very fast. We present a first astrophysical experiment installed at the 'Pic du Midi' site which has detected Cherenkov flashes from cosmic rays with this new semiconductor technology

Studies of avalanche photodiodes for scintillating fibre tracking readout

International Nuclear Information System (INIS)

Fenker, H.; Thomas, J.

1993-01-01

Avalanche Photodiodes (APDs) operating in ''Geiger Mode'' have been studied in a fibre tracking readout environment. A fast recharge circuit has been developed for high rate data taking, and results obtained from a model fibre tracker in the test beam at Brookhaven National Laboratory are presented. A high rate calibrated light source has been developed using a commercially available laser diode and has been used to measure the efficiency of the devices. The transmission of the light from a 1mm fibre onto a 0.5mm diameter APD surface has been identified as the main problem in the use of these particular devices for scintillating fibre tracking in the Superconducting Supercollider environment. Solutions to this problem are proposed

Study of SiPM as a potential photodetector for scintillator readout

International Nuclear Information System (INIS)

Herbert, D.J.; D'Ascenzo, N.; Belcari, N.; Del Guerra, A.; Morsani, F.; Saveliev, V.

2006-01-01

The Silicon PhotoMultiplier (SiPM) APD represents an interesting advance in photodetection and could soon be a rival to traditional PMTs in many applications. The SiPM is effectively a densely packed 2D array of Geiger-mode APD microcells, each having individual resistive quenching and multiplexed outputs. In this way the SiPM acts as a linear, high-gain photodetector for moderate photon flux (N photon cells ). The Metal-Resistor-Silicon (MRS) structure SiPM, produced by CPTA Russia, has been characterised and tested for scintillator light detection in medical applications such as PET. We present a summary of measurements of the device's primary operating characteristics and results of the application to scintillator readout

As the crack in the Geiger counter came. Historical scientific analysis and didactic aspects of the Geiger-Mueller counting tube; Wie das Knacken in den Geigerzaehler kam. Wissenschaftshistorische Analyse und fachdidaktische Aspekte des Geiger-Mueller Zaehlrohrs

Energy Technology Data Exchange (ETDEWEB)

Korff, Sebastian

2014-11-10

This thesis studies the creation and establishment history of this instrument called first electron counting tube in the years 1928 and 1929. It deals thereby with the last two years of the common work of Hans Geiger and Walter Mueller, from which the measuring instrument later renamed to Geiger-Mueller counting tube. The results of this scientific case study are didactically worked out and made usable for the teaching of physics in the school.

Update on Linear Mode Photon Counting with the HgCdTe Linear Mode Avalanche Photodiode

Science.gov (United States)

Beck, Jeffrey D.; Kinch, Mike; Sun, Xiaoli

2014-01-01

The behavior of the gain-voltage characteristic of the mid-wavelength infrared cutoff HgCdTe linear mode avalanche photodiode (e-APD) is discussed both experimentally and theoretically as a function of the width of the multiplication region. Data are shown that demonstrate a strong dependence of the gain at a given bias voltage on the width of the n- gain region. Geometrical and fundamental theoretical models are examined to explain this behavior. The geometrical model takes into account the gain-dependent optical fill factor of the cylindrical APD. The theoretical model is based on the ballistic ionization model being developed for the HgCdTe APD. It is concluded that the fundamental theoretical explanation is the dominant effect. A model is developed that combines both the geometrical and fundamental effects. The model also takes into account the effect of the varying multiplication width in the low bias region of the gain-voltage curve. It is concluded that the lower than expected gain seen in the first 2 × 8 HgCdTe linear mode photon counting APD arrays, and higher excess noise factor, was very likely due to the larger than typical multiplication region length in the photon counting APD pixel design. The implications of these effects on device photon counting performance are discussed.

A simple model of EG and G reverse reach-through APDs

CERN Document Server

Musienko, Y; Swain, J D

2000-01-01

A simple model of reverse reach-through APDs is described. APD parameters including the dependence of the electric field and gain on the bias voltage, dependence of gain on wavelength are calculated using the McIntyre approach and an assumed doping profile of the APD.

A simple model of EG and G reverse reach-through APDs

Energy Technology Data Exchange (ETDEWEB)

Musienko, Y. E-mail: iouri.moussienko@cern.ch; Reucroft, S.; Swain, J

2000-03-11

A simple model of reverse reach-through APDs is described. APD parameters including the dependence of the electric field and gain on the bias voltage, dependence of gain on wavelength are calculated using the McIntyre approach and an assumed doping profile of the APD.

An advanced APD-based spectroscopic radiation monitor. Final Technical Report

International Nuclear Information System (INIS)

Mitchell Woodring, PhD; James Christian, PhD

2007-01-01

A highly sensitized radiation imager is under development through DOE SBIR contract DE-FG02-99ER 82866. This imager will be extraordinarily useful to the DOE in its decontamination and decommissioning activities. The basis for this advanced, state-of-the-art radiation imager is a new type of photon detector, an avalanche photodiode (APD). Only recently has APD technology advanced to the point where it is useful for applications like the radiation imager. To date, the major drawback in the use of avalanche photodiodes was the inability to use many of them in a single application because of the need for many channels of readout, complicated device holders, and dead space between detectors. RMD has solved this dilemma through the development of compact arrays of APDs. Additionally, the fabrication technique has been refined to the point were the bulk production of large quantities of arrays is now feasible. These new APD arrays have excellent application flexibility. The capability to tailor the detector properties; such as size, sensitivity, pixellation, and pitch make APD arrays excellent candidates for a variety of photosensing schemes previously dominated by photomultiplier tubes (PMT). In fact, at RMD it is currently possible to make APD arrays with 2-mm 2 detectors (pixels) in monolithic square arrays 14 pixels on a side (196 detectors). As proposed in Phase II work, paneling 9 of these arrays (as the basis of a highly sensitive radiation imager) would make a photodetector that was 100 cm 2 in sensitive area. This results in approximately 1800 individual detectors that require data sampling and control. This is an enormous electronics load. To reduce the electronics complexity for the readout scheme of APD arrays (one of the major aspects of the proposed Phase II research) individual detectors (in the array) will be grouped together on common readout lines by rows and columns. This row-column-addressing scheme reduces the readout complexity from 1800 to 90 if 42

Stability or instability in avoidant personality disorder:Mode fluctuations within schema therapy sessions.

Science.gov (United States)

Peled, Ofer; Bar-Kalifa, Eran; Rafaeli, Eshkol

2017-12-01

Avoidant personality disorder (APD) is among the most prevalent personality disorders, but has received relatively little empirical attention. This study aims to characterize the frequency, intensity, and fluctuation patterns seen in the modes (self-states) of APD clients over the course of schema therapy (ST), a psychotherapy approach developed especially for personality disorders. The newly-developed client mode rating scale (CMRS) was used to code every 5-min segment (n = 645) of 60 ST sessions. Each segment was coded by two independent raters, achieving adequate reliability. The avoidant/detached mode was present in 74% of therapy segments and was the most intense and unstable mode; the vulnerable child mode was present in 58% of segments and was the second most intense and unstable mode; the dysfunctional parent mode was present in 40% of segments, and was the third most intense and unstable mode; the over-compensator, compliant-surrenderer, and healthy adult modes were present in around 33% of segments, but the healthy adult mode was significantly more stable than all others. Although 645 segments were coded, they were drawn from only 15 APD clients with no control group. Further studies are needed to established specificity to APD. This study demonstrates the utility of the mode concept as a lexicon for capturing personality states and their instability. It highlights the use of in-session segment-by-segment ratings to assess client change within psychotherapy. Although DSM5 fails to address instability as a criterion for avoidant personality disorder, the APD clients in the current study were characterized by considerable mode instability. Copyright © 2017 Elsevier Ltd. All rights reserved.

Updated world map of the Köppen-Geiger climate classification

Directory of Open Access Journals (Sweden)

M. C. Peel

2007-10-01

Full Text Available Although now over 100 years old, the classification of climate originally formulated by Wladimir Köppen and modified by his collaborators and successors, is still in widespread use. It is widely used in teaching school and undergraduate courses on climate. It is also still in regular use by researchers across a range of disciplines as a basis for climatic regionalisation of variables and for assessing the output of global climate models. Here we have produced a new global map of climate using the Köppen-Geiger system based on a large global data set of long-term monthly precipitation and temperature station time series. Climatic variables used in the Köppen-Geiger system were calculated at each station and interpolated between stations using a two-dimensional (latitude and longitude thin-plate spline with tension onto a 0.1°×0.1° grid for each continent. We discuss some problems in dealing with sites that are not uniquely classified into one climate type by the Köppen-Geiger system and assess the outcomes on a continent by continent basis. Globally the most common climate type by land area is BWh (14.2%, Hot desert followed by Aw (11.5%, Tropical savannah. The updated world Köppen-Geiger climate map is freely available electronically in the Supplementary Material Section.

Imaging performance of LabPET APD-based digital PET scanners for pre-clinical research

International Nuclear Information System (INIS)

Bergeron, Mélanie; Cadorette, Jules; Beaudoin, Jean-François; Lecomte, Roger; Tétrault, Marc-André; Leroux, Jean-Daniel; Fontaine, Réjean

2014-01-01

The LabPET is an avalanche photodiode (APD) based digital PET scanner with quasi-individual detector read-out and highly parallel electronic architecture for high-performance in vivo molecular imaging of small animals. The scanner is based on LYSO and LGSO scintillation crystals (2×2×12/14 mm 3 ), assembled side-by-side in phoswich pairs read out by an APD. High spatial resolution is achieved through the individual and independent read-out of an individual APD detector for recording impinging annihilation photons. The LabPET exists in three versions, LabPET4 (3.75 cm axial length), LabPET8 (7.5 cm axial length) and LabPET12 (11.4 cm axial length). This paper focuses on the systematic characterization of the three LabPET versions using two different energy window settings to implement a high-efficiency mode (250–650 keV) and a high-resolution mode (350–650 keV) in the most suitable operating conditions. Prior to measurements, a global timing alignment of the scanners and optimization of the APD operating bias have been carried out. Characteristics such as spatial resolution, absolute sensitivity, count rate performance and image quality have been thoroughly investigated following the NEMA NU 4-2008 protocol. Phantom and small animal images were acquired to assess the scanners' suitability for the most demanding imaging tasks in preclinical biomedical research. The three systems achieve the same radial FBP spatial resolution at 5 mm from the field-of-view center: 1.65/3.40 mm (FWHM/FWTM) for an energy threshold of 250 keV and 1.51/2.97 mm for an energy threshold of 350 keV. The absolute sensitivity for an energy window of 250–650 keV is 1.4%/2.6%/4.3% for LabPET4/8/12, respectively. The best count rate performance peaking at 362 kcps is achieved by the LabPET12 with an energy window of 250–650 keV and a mouse phantom (2.5 cm diameter) at an activity of 2.4 MBq ml −1 . With the same phantom, the scatter fraction for all scanners is about

Single photon detection in a waveguide-coupled Ge-on-Si lateral avalanche photodiode.

Science.gov (United States)

Martinez, Nicholas J D; Gehl, Michael; Derose, Christopher T; Starbuck, Andrew L; Pomerene, Andrew T; Lentine, Anthony L; Trotter, Douglas C; Davids, Paul S

2017-07-10

We examine gated-Geiger mode operation of an integrated waveguide-coupled Ge-on-Si lateral avalanche photodiode (APD) and demonstrate single photon detection at low dark count for this mode of operation. Our integrated waveguide-coupled APD is fabricated using a selective epitaxial Ge-on-Si growth process resulting in a separate absorption and charge multiplication (SACM) design compatible with our silicon photonics platform. Single photon detection efficiency and dark count rate is measured as a function of temperature in order to understand and optimize performance characteristics in this device. We report single photon detection of 5.27% at 1310 nm and a dark count rate of 534 kHz at 80 K for a Ge-on-Si single photon avalanche diode. Dark count rate is the lowest for a Ge-on-Si single photon detector in this range of temperatures while maintaining competitive detection efficiency. A jitter of 105 ps was measured for this device.

Statistical analysis of natural radiation levels inside the UNICAMP campus through the use of Geiger-Muller counter; Analise estatistica dos niveis de radiacao natural dentro da UNICAMP atraves do uso de contador Geiger-Muller

Energy Technology Data Exchange (ETDEWEB)

Fontolan, Juliana A.; Biral, Antonio Renato P., E-mail: fontolanjuliana@gmail.com.br, E-mail: biral@ceb.unicamp.br [Hospital das Clinicas (CEB/UNICAMP), Campinas, SP (Brazil). Centro de Engenharia Biomedica

2013-07-01

It is known that the distribution at time intervals of random and unrelated events leads to the Poisson distribution . This work aims to study the distribution in time intervals of events resulting from radioactive decay of atoms present in the UNICAMP where activities involving the use of ionizing radiation are performed environments . The proposal is that the distribution surveys at intervals of these events in different locations of the university are carried out through the use of a Geiger-Mueller tube . In a next step , the evaluation of distributions obtained by using non- parametric statistics (Chi- square and Kolmogorov Smirnoff) will be taken . For analyzes involving correlations we intend to use the ANOVA (Analysis of Variance) statistical tool . Measured in six different places within the Campinas , with the use of Geiger- Muller its count mode and a time window of 20 seconds was performed . Through statistical tools chi- square and Kolmogorov Smirnoff tests, using the EXCEL program , it was observed that the distributions actually refer to a Poisson distribution. Finally, the next step is to perform analyzes involving correlations using the statistical tool ANOVA.

Characterization of irradiated APDs for picosecond time measurements

Science.gov (United States)

Centis Vignali, M.; Dalal, R.; Gallinaro, M.; Harrop, B.; Jain, G.; Lu, C.; McClish, M.; McDonald, K. T.; Moll, M.; Newcomer, F. M.; Ugobono, S. Otero; White, S.

2018-01-01

For their operation at the CERN High Luminosity Large Hadron Collider (HL-LHC), the ATLAS and CMS experiments are planning to implement dedicated systems to measure the time of arrival of minimum ionizing particles with an accuracy of about 30 ps. The timing detectors will be subjected to radiation levels corresponding up to a 1-MeV neutrons fluence (Φeq) of 1015 cm-2 for the goal integrated luminosity of HL-LHC of 3000 fb-1. In this paper, deep-diffused Avalanche Photo Diodes (APDs) produced by Radiation Monitoring Devices are examined as candidate timing detectors for HL-LHC applications. These APDs are operated at 1.8 kV, resulting in a gain of up to 500. The timing performance of the detectors is evaluated using a pulsed laser. The effects of radiation damage on current, signal amplitude, noise, and timing performance of the APDs are evaluated using detectors irradiated with neutrons up to Φeq = 1015 cm-2.

Temperature dependence of APD-based PET scanners

International Nuclear Information System (INIS)

Keereman, Vincent; Van Holen, Roel; Vandenberghe, Stefaan; Vanhove, Christian

2013-01-01

Purpose: Solid state detectors such as avalanche photodiodes (APDs) are increasingly being used in PET detectors. One of the disadvantages of APDs is the strong decrease of their gain factor with increasing ambient temperature. The light yield of most scintillation crystals also decreases when ambient temperature is increased. Both effects lead to considerable temperature dependence of the performance of APD-based PET scanners. In this paper, the authors propose a model for this dependence and the performance of the LabPET8 APD-based small animal PET scanner is evaluated at different temperatures.Methods: The model proposes that the effect of increasing temperature on the energy histogram of an APD-based PET scanner is a compression of the histogram along the energy axis. The energy histogram of the LabPET system was acquired at 21 °C and 25 °C to verify the validity of this model. Using the proposed model, the effect of temperature on system sensitivity was simulated for different detector temperature coefficients and temperatures. Subsequently, the effect of short term and long term temperature changes on the peak sensitivity of the LabPET system was measured. The axial sensitivity profile was measured at 21 °C and 24 °C following the NEMA NU 4-2008 standard. System spatial resolution was also evaluated. Furthermore, scatter fraction, count losses and random coincidences were evaluated at different temperatures. Image quality was also investigated.Results: As predicted by the model, the photopeak energy at 25 °C is lower than at 21 °C with a shift of approximately 6% per °C. Simulations showed that this results in an approximately linear decrease of sensitivity when temperature is increased from 21 °C to 24 °C and energy thresholds are constant. Experimental evaluation of the peak sensitivity at different temperatures showed a strong linear correlation for short term (2.32 kcps/MBq/°C = 12%/°C, R = −0.95) and long term (1.92 kcps/MBq/°C = 10%/�

Optimization of single photon detection model based on GM-APD

Science.gov (United States)

Chen, Yu; Yang, Yi; Hao, Peiyu

2017-11-01

One hundred kilometers high precision laser ranging hopes the detector has very strong detection ability for very weak light. At present, Geiger-Mode of Avalanche Photodiode has more use. It has high sensitivity and high photoelectric conversion efficiency. Selecting and designing the detector parameters according to the system index is of great importance to the improvement of photon detection efficiency. Design optimization requires a good model. In this paper, we research the existing Poisson distribution model, and consider the important detector parameters of dark count rate, dead time, quantum efficiency and so on. We improve the optimization of detection model, select the appropriate parameters to achieve optimal photon detection efficiency. The simulation is carried out by using Matlab and compared with the actual test results. The rationality of the model is verified. It has certain reference value in engineering applications.

Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

Energy Technology Data Exchange (ETDEWEB)

Thil, Ch., E-mail: christophe.thil@ziti.uni-heidelberg.d [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Baron, A.Q.R. [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Fajardo, P. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France); Fischer, P. [Heidelberg University, Institute of Computer Engineering, B6, 26, 68161 Mannheim (Germany); Graafsma, H. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Rueffer, R. [ESRF, Polygone Scientifique Louis Neel, 6, rue Jules Horowitz, 38000 Grenoble (France)

2011-02-01

The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm{sup 2} active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280{mu}mx280{mu}m size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

Pixel readout ASIC for an APD based 2D X-ray hybrid pixel detector with sub-nanosecond resolution

International Nuclear Information System (INIS)

Thil, Ch.; Baron, A.Q.R.; Fajardo, P.; Fischer, P.; Graafsma, H.; Rueffer, R.

2011-01-01

The fast response and the short recovery time of avalanche photodiodes (APDs) in linear mode make those devices ideal for direct X-ray detection in applications requiring high time resolution or counting rate. In order to provide position sensitivity, the XNAP project aims at creating a hybrid pixel detector with nanosecond time resolution based on a monolithic APD sensor array with 32 x32 pixels covering about 1 cm 2 active area. The readout is implemented in a pixelated front-end ASIC suited for the readout of such arrays, matched to pixels of 280μmx280μm size. Every single channel features a fast transimpedance amplifier, a discriminator with locally adjustable threshold and two counters with high dynamic range and counting speed able to accumulate X-ray hits with no readout dead time. Additionally, the detector can be operated in list mode by time-stamping every single event with sub-nanosecond resolution. In a first phase of the project, a 4x4 pixel test module is built to validate the conceptual design of the detector. The XNAP project is briefly presented and the performance of the readout ASIC is discussed.

DOI resolution measurement and error analysis with LYSO and APDs

International Nuclear Information System (INIS)

Lee, Chae-hun; Cho, Gyuseong

2008-01-01

Spatial resolution degradation in PET occurs at the edge of Field Of View (FOV) due to parallax error. To improve spatial resolution at the edge of FOV, Depth-Of-Interaction (DOI) PET has been investigated and several methods for DOI positioning were proposed. In this paper, a DOI-PET detector module using two 8x4 array avalanche photodiodes (APDs) (Hamamatsu, S8550) and a 2 cm long LYSO scintillation crystal was proposed and its DOI characteristics were investigated experimentally. In order to measure DOI positions, signals from two APDs were compared. Energy resolution was obtained from the sum of two APDs' signals and DOI positioning error was calculated. Finally, an optimum DOI step size in a 2 cm long LYSO were suggested to help to design a DOI-PET

Epstein–Barr Virus Susceptibility in Activated PI3Kδ Syndrome (APDS Immunodeficiency

Directory of Open Access Journals (Sweden)

Jean-Marie Carpier

2018-01-01

Full Text Available Activated PI3Kδ Syndrome (APDS is an inherited immune disorder caused by heterozygous, gain-of-function mutations in the genes encoding the phosphoinositide 3-kinase delta (PI3Kδ subunits p110δ or p85δ. This recently described primary immunodeficiency disease (PID is characterized by recurrent sinopulmonary infections, lymphoproliferation, and susceptibility to herpesviruses, with Epstein–Barr virus (EBV infection being most notable. A broad range of PIDs having disparate, molecularly defined genetic etiology can cause susceptibility to EBV, lymphoproliferative disease, and lymphoma. Historically, PID patients with loss-of-function mutations causing defective cell-mediated cytotoxicity or antigen receptor signaling were found to be highly susceptible to pathological EBV infection. By contrast, the gain of function in PI3K signaling observed in APDS patients paradoxically renders these patients susceptible to EBV, though the underlying mechanisms are incompletely understood. At a cellular level, APDS patients exhibit deranged B lymphocyte development and defects in class switch recombination, which generally lead to defective immunoglobulin production. Moreover, APDS patients also demonstrate an abnormal skewing of T cells toward terminal effectors with short telomeres and senescence markers. Here, we review APDS with a particular focus on how the altered lymphocyte biology in these patients may confer EBV susceptibility.

Statistical analysis of natural radiation levels inside the UNICAMP campus through the use of Geiger-Muller counter

International Nuclear Information System (INIS)

Fontolan, Juliana A.; Biral, Antonio Renato P.

2013-01-01

It is known that the distribution at time intervals of random and unrelated events leads to the Poisson distribution . This work aims to study the distribution in time intervals of events resulting from radioactive decay of atoms present in the UNICAMP where activities involving the use of ionizing radiation are performed environments . The proposal is that the distribution surveys at intervals of these events in different locations of the university are carried out through the use of a Geiger-Mueller tube . In a next step , the evaluation of distributions obtained by using non- parametric statistics (Chi- square and Kolmogorov Smirnoff) will be taken . For analyzes involving correlations we intend to use the ANOVA (Analysis of Variance) statistical tool . Measured in six different places within the Campinas , with the use of Geiger- Muller its count mode and a time window of 20 seconds was performed . Through statistical tools chi- square and Kolmogorov Smirnoff tests, using the EXCEL program , it was observed that the distributions actually refer to a Poisson distribution. Finally, the next step is to perform analyzes involving correlations using the statistical tool ANOVA

Radiation damage of pixelated photon detector by neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Isamu [KEK, 1-1 Oho Tsukuba 305-0801 (Japan)], E-mail: isamu.nakamura@kek.jp

2009-10-21

Radiation Damage of Pixelated Photon Detector by neutron irradiation is reported. MPPC, one of PPD or Geiger-mode APD, developed by Hamamatsu Photonics, is planned to be used in many high energy physics experiments. In such experiments radiation damage is a serious issue. A series of neutron irradiation tests is performed at the Reactor YAYOI of the University of Tokyo. MPPCs were irradiated at the reactor up to 10{sup 12}neutron/cm{sup 2}. In this paper, the effect of neutron irradiation on the basic characteristics of PPD including gain, noise rate, photon detection efficiency is presented.

Photon-counting monolithic avalanche photodiode arrays for the super collider

International Nuclear Information System (INIS)

Ishaque, A.N.; Castleberry, D.E.; Rougeot, H.M.

1994-01-01

In fiber tracking, calorimetry, and other high energy and nuclear physics experiments, the need arises to detect an optical signal consisting of a few photons (in some cases a single photoelectron) with a detector insensitive to magnetic fields. Previous attempts to detect a single photoelectron have involved avalanche photodiodes (APDs) operated in the Geiger mode, the visible light photon counter, and a photomultiplier tube with an APD as the anode. In this paper it is demonstrated that silicon APDs, biased below the breakdown voltage, can be used to detect a signal of a few photons with conventional pulse counting circuitry at room temperature. Moderate cooling, it is further argued, could make it possible to detect a single photoelectron. Monolithic arrays of silicon avalanche photodiodes fabricated by Radiation Monitoring Devices, Inc. (RMD) were evaluated for possible use in the Super Collider detector systems. Measurements on 3 element x 3 element (2 mm pitch) APD arrays, using pulse counting circuitry with a charge sensitive amplifier (CSA) and a Gaussian filter, are reported and found to conform to a simple noise model. The model is used to obtain the optimal operating point. Experimental results are described in Section II, modeling results in Section III, and the conclusions are summarized in Section IV

Geiger counters of gamma rays with a bismuth cathode; Compteurs de geiger a rayons gamma a cathode de bismuth

Energy Technology Data Exchange (ETDEWEB)

Meunier, R; Legrand, J P [Commissariat a l' Energie Atomique, Saclay(France). Centre d' Etudes Nucleaires

1953-07-01

Geiger Muller counters present a lake of efficiency of some per cent, for the {gamma} radiations. In the region 0,3 - 1 MeV, a substantial growth of their output can be obtained by a special construction of their cathode. In accordance with previous works, we constructed some counter of formed cathode by a pleated copper wire fencing covered of Bi by electrolysis. The successive modifications brought to a cylindrical conventional cathode in sheet metal of copper, that succeeds to this type of cathode, drive to an improvement of the output. (M.B.) [French] Les compteurs de Geiger Muller presentent une efficacite assez faible de l'ordre de quelques pour cent, pour les rayonnements {gamma}. Dans la region 0,3 - 1 MeV, un accroissement substantiel de leur rendement peut etre obtenu par une construction speciale de leur cathode. Conformement a des travaux anterieurs, nous avons construit des compteurs a cathode formee par un grillage de cuivre plisse recouvert de Bi par electrolyse. Les modifications successives apportees a une cathode conventionnelle cylindrique en tole de cuivre, qui aboutissent a ce type de cathode, conduisent a une amelioration du rendement. (M.B.)

Multiple benefits of personal FM system use by children with auditory processing disorder (APD).

Science.gov (United States)

Johnston, Kristin N; John, Andrew B; Kreisman, Nicole V; Hall, James W; Crandell, Carl C

2009-01-01

Children with auditory processing disorders (APD) were fitted with Phonak EduLink FM devices for home and classroom use. Baseline measures of the children with APD, prior to FM use, documented significantly lower speech-perception scores, evidence of decreased academic performance, and psychosocial problems in comparison to an age- and gender-matched control group. Repeated measures during the school year demonstrated speech-perception improvement in noisy classroom environments as well as significant academic and psychosocial benefits. Compared with the control group, the children with APD showed greater speech-perception advantage with FM technology. Notably, after prolonged FM use, even unaided (no FM device) speech-perception performance was improved in the children with APD, suggesting the possibility of fundamentally enhanced auditory system function.

Studies on multiplication effect of noises of PPD, and a proposal of a new structure to improve the performance

Energy Technology Data Exchange (ETDEWEB)

Oide, H., E-mail: oide@icepp.s.u-tokyo.ac.j [Department of Physics, University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-0033 (Japan); Murase, T.; Otono, H. [Department of Physics, University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-0033 (Japan); Yamashita, S. [ICEPP, University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-0033 (Japan)

2010-11-01

Pixelated photon detectors (PPDs) are arrayed APDs operated in Geiger-mode. Multi-pixel photon counter (MPPC) is a PPD produced by Hamamatsu Photonics K.K. We performed measurement of total noise rate, random noise rate, after-pulsing, crosstalk, and relative photon detection efficiency for a 1600 px MPPC. The explosive increase of total noise rate to over-voltage is able to be understood of multiplication effect of after-pulsing and crosstalk. Considering the electric field structure of MPPC (p-on-n type) and Geiger-efficiency as a function of the position of initial pair creation, these characteristics are all able to be understood. One suggestion for p-on-n type PPD from these results is narrowing the depletion layer below the multiplication layer to reduce random noise and after-pulsing. Another proposal is to put additional buffer capacitance parallel to the diode to accomplish higher gain with lower over-voltage simultaneously with lower noise rate.

Studies on multiplication effect of noises of PPD, and a proposal of a new structure to improve the performance

International Nuclear Information System (INIS)

Oide, H.; Murase, T.; Otono, H.; Yamashita, S.

2010-01-01

Pixelated photon detectors (PPDs) are arrayed APDs operated in Geiger-mode. Multi-pixel photon counter (MPPC) is a PPD produced by Hamamatsu Photonics K.K. We performed measurement of total noise rate, random noise rate, after-pulsing, crosstalk, and relative photon detection efficiency for a 1600 px MPPC. The explosive increase of total noise rate to over-voltage is able to be understood of multiplication effect of after-pulsing and crosstalk. Considering the electric field structure of MPPC (p-on-n type) and Geiger-efficiency as a function of the position of initial pair creation, these characteristics are all able to be understood. One suggestion for p-on-n type PPD from these results is narrowing the depletion layer below the multiplication layer to reduce random noise and after-pulsing. Another proposal is to put additional buffer capacitance parallel to the diode to accomplish higher gain with lower over-voltage simultaneously with lower noise rate.

Geiger-Mueller counter for mixed neutron-gamma beam dosimetry

International Nuclear Information System (INIS)

McDonald, J.C.; Ma, I.-C.

1978-01-01

A Geiger-Mueller (G-M) dosimeter has been constructed and employed to measure the gamma-ray component of absorbed dose in a cyclotron produced fast neutron field. This instrument is waterproof for measurements in a liquid medium, and read-out is accompanied with any standard scaler. (Auth.)

Pulse oximeter using a gain-modulated avalanche photodiode operated in a pseudo lock-in light detection mode

Science.gov (United States)

Miyata, Tsuyoshi; Iwata, Tetsuo; Araki, Tsutomu

2006-01-01

We propose a reflection-type pulse oximeter, which employs two pairs of a light-emitting diode (LED) and a gated avalanche photodiode (APD). One LED is a red one with an emission wavelength λ = 635 nm and the other is a near-infrared one with that λ = 945 nm, which are both driven with a pulse mode at a frequency f (=10 kHz). Superposition of a transistor-transistor-logic (TTL) gate pulse on a direct-current (dc) bias, which is set so as not exceeding the breakdown voltage of each APD, makes the APD work in a gain-enhanced operation mode. Each APD is gated at a frequency 2f (=20 kHz) and its output signal is fed into a laboratory-made lock-in amplifier that works in synchronous with the pulse modulation signal of each LED at a frequency f (=10 kHz). A combination of the gated APD and the lock-in like signal detection scheme is useful for the reflection-type pulse oximeter thanks to the capability of detecting a weak signal against a large background (BG) light.

Single-photon semiconductor photodiodes for distributed optical fiber sensors: state of the art and perspectives

Science.gov (United States)

Ripamonti, Giancarlo; Lacaita, Andrea L.

1993-03-01

The extreme sensitivity and time resolution of Geiger-mode avalanche photodiodes (GM- APDs) have already been exploited for optical time domain reflectometry (OTDR). Better than 1 cm spatial resolution in Rayleigh scattering detection was demonstrated. Distributed and quasi-distributed optical fiber sensors can take advantage of the capabilities of GM-APDs. Extensive studies have recently disclosed the main characteristics and limitations of silicon devices, both commercially available and developmental. In this paper we report an analysis of the performance of these detectors. The main characteristics of GM-APDs of interest for distributed optical fiber sensors are briefly reviewed. Command electronics (active quenching) is then introduced. The detector timing performance sets the maximum spatial resolution in experiments employing OTDR techniques. We highlight that the achievable time resolution depends on the physics of the avalanche spreading over the device area. On the basis of these results, trade-off between the important parameters (quantum efficiency, time resolution, background noise, and afterpulsing effects) is considered. Finally, we show first results on Germanium devices, capable of single photon sensitivity at 1.3 and 1.5 micrometers with sub- nanosecond time resolution.

Geiger-Muller with a mica window halogen quenched counters aspects

International Nuclear Information System (INIS)

Gorski, M.S.; Bruzinga, W.A.

1990-09-01

We present the development of a model of a Geiger-Muller with likeness the model ZP 1410 Phillips. The prototype has a cylindrical shape with 37mm of effective length and a mica window of 1,5 to 2,0mg/cm sup(2) thickness with a useful diam of 19,8mm. For the window preparation and special cutting technique was developed Basically two types of quenching agents, bromine and chlorine were studied. Due to the high corrosive nature of these gases, we work with treatment of surface of the cathode through electropolishment, chemical passiveness, hard chrome and nickel coating. Out main objective was to get a Geiger-Muller detector with an operational plateau over 200V, working voltage above 600V and a sensivity of 320 counts/sec at 10 sup(-1) m Gy/h. (author)

Geiger-Muller (GM) counters. Associated circuits and counting techniques; Les compteurs de Geiger-Muller (GM). Les circuits associes et techniques de comptage

Energy Technology Data Exchange (ETDEWEB)

Benoit, A.; Picard, E. [Commissariat a l' Energie Atomique, Centre d' Etudes Nucleaires de Saclay (France)

1954-07-01

This article presents the Geiger-Muller counters which present the great benefit of being simple and steady in comparison with other known sensors. The authors propose an overview of problems related to the use of Geiger-Muller counters (GM counters). They first describe their operation (discharge initiation, discharge propagation, collection of positive ions and current in the counter). They discuss their limitations which are related to the migration delay of primary electrons and positive ions. They describe the operation circuit for counters with organic vapour, and for counters associated with counters using halogens. They address the main properties of GM counters, and the different factors to be taken into account when using them to count radioactive sources. The main types of GM counters are then described (they are used to measure different types of radiation). Measurement techniques are discussed for beta radiation (relationship between the number of disintegrations and the noticed counting rate, case of backscattering, absorption and diffusion in the counter window and in the air, influence of absorption and backscattering in the source), for alpha radiation, and for gamma radiation.

Detectors for proton counting. Si-APD and scintillation detectors

International Nuclear Information System (INIS)

Kishimoto, Shunji

2008-01-01

Increased intensity of synchrotron radiation requests users to prepare photon pulse detectors having higher counting rates. As detectors for photon counting, silicon-avalanche photodiode (Si-APD) and scintillation detectors were chosen for the fifth series of detectors. Principle of photon detection by pulse and need of amplification function of the detector were described. Structure and working principle, high counting rate measurement system, bunch of electrons vs. counting rate, application example of NMR time spectroscopy measurement and comments for users were described for the Si-APD detector. Structure of scintillator and photomultiplier tube, characteristics of scintillator and performance of detector were shown for the NaI detector. Future development of photon pulse detectors was discussed. (T. Tanaka)

Performances of a HGCDTE APD based direct detection lidar at 2 μm. Application to dial measurements

Science.gov (United States)

Gibert, Fabien; Dumas, Arnaud; Rothman, Johan; Edouart, Dimitri; Cénac, Claire; Pellegrino, Jessica

2018-04-01

A lidar receiver with a direct detection chain adapted to a HgCdTe APD based detector with electric cooling is associated to a 2.05 μm Ho :YLF pulsed dual wavelength single mode transmitter to provide the first atmospheric lidar measurements using this technology. Experiments confirm the outstanding sensitivity of the detector and hightligth its huge potential for DIAL measurements of trace gas (CO2 and H2O) in this spectral domain. Performances of coherent vs direct detection at 2.05 μm is assessed.

Performances of a HGCDTE APD based direct detection lidar at 2 μm. Application to dial measurements

Directory of Open Access Journals (Sweden)

Gibert Fabien

2018-01-01

Full Text Available A lidar receiver with a direct detection chain adapted to a HgCdTe APD based detector with electric cooling is associated to a 2.05 μm Ho :YLF pulsed dual wavelength single mode transmitter to provide the first atmospheric lidar measurements using this technology. Experiments confirm the outstanding sensitivity of the detector and hightligth its huge potential for DIAL measurements of trace gas (CO2 and H2O in this spectral domain. Performances of coherent vs direct detection at 2.05 μm is assessed.

Study on APD real time compensation methods of laser Detection system

International Nuclear Information System (INIS)

Feng Ying; Zhang He; Zhang Xiangjin; Liu Kun

2011-01-01

With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained by analyzing

Study on APD real time compensation methods of laser Detection system

Energy Technology Data Exchange (ETDEWEB)

Feng Ying; Zhang He; Zhang Xiangjin; Liu Kun, E-mail: fy_caimi@163.com [ZNDY of Ministerial Key Laboratory, Nanjing University of Science and Technology, Nanjing 210094 (China)

2011-02-01

With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained

Study on APD real time compensation methods of laser Detection system

Science.gov (United States)

Ying, Feng; He, Zhang; Xiangjin, Zhang; Kun, Liu

2011-02-01

With the monochromatic and the directional capability of the laser, laser detection system is confidential in anti-jamming. Detection accuracy is improved significantly as the result of laser's good orientation ability. Sensitivity is enhanced as laser's high-brightness characteristic. With the development of laser technology and laser devices, laser detections are developed both in civilian and military areas. In the military field, laser detection system has been widely applied in various types of tactical missiles, the technique is more mature. Because photo detectors receive the backscattering echo signal of target in laser detection system, they are required sensitive enough to weak signal. With APD's salient features of high sensitivity, rapid response speed, high response frequency and low noise equivalent power, etc.; PIN is replaced by APD to improve sensitivity of laser detection system in recent years. The signal magnification is inadequate in laser detection system, the detector output is usually amplified by multistage amplifiers. And then the system noise includes detector noise and latter amplifiers noise. With its high internal gain, APD becomes the primary noise source of receiving system. This point can be attested by analyzing the transfer function of laser detection system receiver. To ensure the system detecting ability, APD noise must be mitigated as low as possible. According to a large number of experiments, the power signal-to-noise (SNR) and the best multiplication factor of APD are mostly affected by background radiation and temperature. In order to make APD operate at state of the best multiplication factor, the optimum bias must be selected due to the actual operating circumstance. Therefore, APD realtime compensation must be adopted. The existing APD compensation includes the constant false alarm rate compensation, the noise compensation and the temperature compensation. The features of these compensations are obtained by analyzing

An integrated fluorescence detection system in poly(dimethylsiloxane) for microfluidic applications.

Science.gov (United States)

Chabinyc, M L; Chiu, D T; McDonald, J C; Stroock, A D; Christian, J F; Karger, A M; Whitesides, G M

2001-09-15

This paper describes a prototype of an integrated fluorescence detection system that uses a microavalanche photodiode (microAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The prototype device consisted of a reusable detection system and a disposable microfluidic system that was fabricated using rapid prototyping. The first step of the procedure was the fabrication of microfluidic channels in PDMS and the encapsulation of a multimode optical fiber (100-microm core diameter) in the PDMS; the tip of the fiber was placed next to the side wall of one of the channels. The optical fiber was used to couple light into the microchannel for the excitation of fluorescent analytes. The photodetector, a prototype solid-state microAPD array, was embedded in a thick slab (1 cm) of PDMS. A thin (80 microm) colored polycarbonate filter was placed on the top of the embedded microAPD to absorb scattered excitation light before it reached the detector. The microAPD was placed below the microchannel and orthogonal to the axis of the optical fiber. The close proximity (approximately 200 microm) of the microAPD to the microchannel made it unnecessary to incorporate transfer optics; the pixel size of the microAPD (30 microm) matched the dimensions of the channels (50 microm). A blue light-emitting diode was used for fluorescence excitation. The microAPD was operated in Geiger mode to detect the fluorescence. The detection limit of the prototype (approximately 25 nM) was determined by finding the minimum detectable concentration of a solution of fluorescein. The device was used to detect the separation of a mixture of proteins and small molecules by capillary electrophoresis; the separation illustrated the suitability of this integrated fluorescence detection system for bioanalytical applications.

Use of Fall-Risk Inducing Drugs in Patients Using Anti-Parkinson Drugs (APD: A Swedish Register-Based Study.

Directory of Open Access Journals (Sweden)

Ylva Haasum

Full Text Available Many drugs increase the risk of falls in old age. Although persons with Parkinson's disease (PD are at increased risk of experiencing falls and fractures, the use of fall-risk inducing drugs (FRIDs in this population has not previously been investigated. The objective of this study was to investigate the burden of use of FRIDs in older persons treated with anti-Parkinson drugs (APD; used as a proxy for PD, compared to persons without APD.We analyzed individual data on age, sex, type of housing and drug use in 1 346 709 persons aged ≥ 65 years in the Swedish Prescribed Drug Register on the date of 30 September 2008. Main outcome measure was the use of FRIDs.FRIDs were used by 79% of persons with APD and 75% of persons without APD. Persons with APD were more likely to use ≥ 1 FRIDs compared to persons without APD (adjusted OR: 1.09; 95% CI: 1.06-1-12. The association was stronger for concomitant use of ≥ 5 FRIDS (adjusted OR: 1.49; 95% CI: 1.44-1.55.The high use of FRIDs among persons with APD indicates that these patients may be at increased risk of drug-induced falls. Further studies are needed to investigate how these drugs affect the risk of falling in persons with PD.

Development of a 32-channel ASIC for an X-ray APD detector onboard the ISS

Science.gov (United States)

Arimoto, Makoto; Harita, Shohei; Sugita, Satoshi; Yatsu, Yoichi; Kawai, Nobuyuki; Ikeda, Hirokazu; Tomida, Hiroshi; Isobe, Naoki; Ueno, Shiro; Mihara, Tatehiro; Serino, Motoko; Kohmura, Takayoshi; Sakamoto, Takanori; Yoshida, Atsumasa; Tsunemi, Hiroshi; Hatori, Satoshi; Kume, Kyo; Hasegawa, Takashi

2018-02-01

We report on the design and performance of a mixed-signal application specific integrated circuit (ASIC) dedicated to avalanche photodiodes (APDs) in order to detect hard X-ray emissions in a wide energy band onboard the International Space Station. To realize wide-band detection from 20 keV to 1 MeV, we use Ce:GAGG scintillators, each coupled to an APD, with low-noise front-end electronics capable of achieving a minimum energy detection threshold of 20 keV. The developed ASIC has the ability to read out 32-channel APD signals using 0.35 μm CMOS technology, and an analog amplifier at the input stage is designed to suppress the capacitive noise primarily arising from the large detector capacitance of the APDs. The ASIC achieves a performance of 2099 e- + 1.5 e-/pF at root mean square (RMS) with a wide 300 fC dynamic range. Coupling a reverse-type APD with a Ce:GAGG scintillator, we obtain an energy resolution of 6.7% (FWHM) at 662 keV and a minimum detectable energy of 20 keV at room temperature (20 °C). Furthermore, we examine the radiation tolerance for space applications by using a 90 MeV proton beam, confirming that the ASIC is free of single-event effects and can operate properly without serious degradation in analog and digital processing.

FACT light collection - solid light concentrators in Cherenkov Astronomy

Energy Technology Data Exchange (ETDEWEB)

Braun, Isabel [ETH Zurich, Institute for Particle Physics, CH-8093 Zurich (Switzerland); Collaboration: FACT-Collaboration

2011-07-01

Pixelized cameras of Imaging Atmospheric Cherenkov Telescopes use hollow light guides with reflective surfaces based on the Winston cone design. These cones minimize insensitive spaces between the photo sensors and shield the camera from stray background light by limiting the angular acceptance to the primary reflector area. FACT (First G-APD Cherenkov Telescope) will be the first IACT with Geiger-mode avalanche photodiodes as light sensors. Solid light concentrators complementing these sensors will be used instead of hollow Winston cones. We will present simulations and measurements of our light collector design, which was optimized for the requirements of the FACT telescope and detector, and discuss the specific differences to more traditional solutions.

AX-PET A novel PET detector concept with full 3D reconstruction

CERN Document Server

Braem, A; Séguinot, J; Dissertori, G; Djambazov, L; Lustermann, W; Nessi-Tedaldi, F; Pauss, F; Schinzel, D; Solevi, P; Lacasta, C; Oliver, J F; Rafecas, M; De Leo, R; Nappi, E; Vilardi, I; Chesi, E; Cochran, E; Honscheid, K; Kagan, H; Rudge, A; Smith, S; Weilhammer, P; Johnson, I; Renker, D; Clinthorne, N; Huh, S; Bolle, E; Stapnes, S; Meddi, F

2009-01-01

We describe the concept and first experimental tests of a novel 3D axial Positron Emission Tomography (PET) geometry. It allows for a new way of measuring the interaction point in the detector with very high precision. It is based on a matrix of long Lutetium-Yttrium OxyorthoSilicate (LYSO) crystals oriented in the axial direction, each coupled to one Geiger Mode Avalanche Photodiode (G-APD) array. To derive the axial coordinate, Wave Length Shifter (WLS) strips are mounted orthogonally and interleaved between the crystals. The light from the WLS strips is read by custom-made G-APDs. The weighted mean of the signals in the WLS strips has proven to give very precise axial resolution. The achievable resolution along the three axes is mainly driven by the dimensions of the LYSO crystals and WLS strips. This concept is inherently free of parallax errors. Furthermore, it will allow identification of Compton interactions in the detector and for reconstruction of a fraction of them, which is expected to enhance imag...

Application of a background-compensated Geiger-Mueller counter to a survey meter

International Nuclear Information System (INIS)

Mori, C.; Kumanomido, H.; Watanabe, T.

1984-01-01

A background-compensated Geiger-Mueller counter was used as a probe for a GM survey meter to obtain a net count rate of β-rays from a radioactive source in a quick survey. Although a background counting ratio between the two parts in the counter, front and rear, varied somewhat depending on the incident direction of background γ-rays, it was possible to compensate the background counts by subtracting a part of the rear counts, which were background counts, from the front counts, which contained β-ray counts and background counts. Undesirable small pulses generated during the recovering time after a full Geiger discharge were eliminated by an anticoincidence gating method. The survey meter with this counter and a differential ratemeter is useful for obtaining a net count rate of β-rays emitted from a surface radioactive-contamination or from a source being put near the window of the counter with nearly the same accuracy in half the measuring time as compared with conventional GM counters. (orig.)

Novel method of using 99mTc-APD (pamidronate) to monitor delivery of bisphosphonates to bone without renal burden

International Nuclear Information System (INIS)

Kumar, V.; Wong, E.; Kumar, D.; Howman-Giles, R.; Little, D.G.

2004-01-01

Purpose: Bisphosphonates (BP) were first used in the 1960's when their ability to bind to bone mineral hydroxyapatite made them a useful tool for studying orthopaedic bone repair processes. From being an experimental agent, now BP have become the treatment of choice for clinical disorders associated with increased bone resorption, such as osteoporosis, myeloma and bone metastasis. While the effectiveness of BP in managing these disorders is commendable, they have certain undesirable side effects. For example, intravenous injection of Pamidronate may be associated with nephrocalcinosis of the kidneys. Therefore there is a need to develop a novel technique to demonstrate the localisation of the compound, which can be visualized within hours of administering into the patients. The Objective of the study is to develop 99mTc-labelled APD (Pamidronate) as a new tool and monitor its biodistribution by gamma imaging modality. This approach has not been reported elsewhere in the literature and has the potential to improve the quality of treatment currently available. Methods: Pamidronate (APD) was labelled with 99mTc-pertechnetate in the presence of Stannous Chloride as the reducing agent. The radiochemical purity (RCP) of the compound was determined by ITLC-SG/Acetone and found to be >99%. Rats were injected with 99mTc-APD intravenously (IV) subcutaneously (SC) and by direct application (Local) on surgically exposed femur. The animals were sacrificed at 2hr or 24hr post-injection and various organs were harvested and counted for radioactivity with a view to establish the biodistribution of 99mTc-APD. Results: 99mTc-APD was injected by three different modes as indicated in the Methods section. Planar and SPECT images were obtained at 2 hr and 24 hr post-injection. Intravenous injection (IV): When 99mTc-APD was administered IV, the labelled compound appeared instantly in the blood pool. The 2 hr and 24 hr images clearly showed that the labelled compound accumulated

Ultraviolet Light Curves of Gaia16apd in Superluminous Supernova Models

Energy Technology Data Exchange (ETDEWEB)

Tolstov, Alexey; Zhiglo, Andrey; Nomoto, Ken’ichi; Blinnikov, Sergei [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan); Sorokina, Elena [Sternberg Astronomical Institute, M.V.Lomonosov Moscow State University, 119234 Moscow (Russian Federation); Kozyreva, Alexandra, E-mail: alexey.tolstov@ipmu.jp [The Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel)

2017-08-10

Observations of Gaia16apd revealed extremely luminous ultraviolet emission among superluminous supernovae (SLSNe). Using radiation hydrodynamics simulations, we perform a comparison of UV light curves, color temperatures, and photospheric velocities between the most popular SLSN models: pair-instability supernova, magnetar, and interaction with circumstellar medium. We find that the interaction model is the most promising to explain the extreme UV luminosity of Gaia16apd. The differences in late-time UV emission and in color evolution found between the models can be used to link an observed SLSN event to the most appropriate model. Observations at UV wavelengths can be used to clarify the nature of SLSNe and more attention should be paid to them in future follow-up observations.

ASIC Readout Circuit Architecture for Large Geiger Photodiode Arrays

Science.gov (United States)

Vasile, Stefan; Lipson, Jerold

2012-01-01

The objective of this work was to develop a new class of readout integrated circuit (ROIC) arrays to be operated with Geiger avalanche photodiode (GPD) arrays, by integrating multiple functions at the pixel level (smart-pixel or active pixel technology) in 250-nm CMOS (complementary metal oxide semiconductor) processes. In order to pack a maximum of functions within a minimum pixel size, the ROIC array is a full, custom application-specific integrated circuit (ASIC) design using a mixed-signal CMOS process with compact primitive layout cells. The ROIC array was processed to allow assembly in bump-bonding technology with photon-counting infrared detector arrays into 3-D imaging cameras (LADAR). The ROIC architecture was designed to work with either common- anode Si GPD arrays or common-cathode InGaAs GPD arrays. The current ROIC pixel design is hardwired prior to processing one of the two GPD array configurations, and it has the provision to allow soft reconfiguration to either array (to be implemented into the next ROIC array generation). The ROIC pixel architecture implements the Geiger avalanche quenching, bias, reset, and time to digital conversion (TDC) functions in full-digital design, and uses time domain over-sampling (vernier) to allow high temporal resolution at low clock rates, increased data yield, and improved utilization of the laser beam.

General Roy S. Geiger, USMC: Marine Aviator, Joint Force Commander

Science.gov (United States)

2007-06-01

This is a strong assertion, given the significant and better-known contributions of great Marines such as John Lejeune, Smedley Butler, Alexander...While stationed in Panama, Geiger made a favorable impression on Major Smedley Butler, who later earned the Medal of Honor twice and became a...fifth Naval Aviator. 43 Johnson, 5. 44 Robert Sherrod, History of Marine Corps Aviation in World War II (Baltimore, MD: The Nautical and Aviation

APD Properties and Recovery from Radiation Damage

CERN Document Server

Baccaro, Stefania; Caruso, S; Cavallari, Francesca; Dafinei, Ioan; Diemoz, Marcella; Emeliantchik, Igor; Festinesi, Armando; Longo, Egidio; Montecchi, Marco; Organtini, Giovanni; Rosi, G

1997-01-01

Avalanche photodiodes will be used to detect scintillation light from PWO crystals in the CMS electromagnetic calorimeter. Properties of Hamamatsu APD are reported special attention has been devoted to the study of radiation hardness and room temperature annealing. We found a fast recovery with a time constant of 1.3 days a medium fast recovery with a lifetime of the order of 10 days and indication of a third component with very long time constant of the order of 300 days.

The New APD Based Readout for the Crystal Barrel Calorimeter

International Nuclear Information System (INIS)

Urban, M; Honisch, Ch; Steinacher, M

2015-01-01

The CBELSA/TAPS experiment at ELSA measures double polarization observables in meson photoproduction off protons and neutrons. To be able to measure purely neutral reactions off polarized neutrons with high efficiency, the main calorimeter has to be integrated into the first level trigger. This requires to exchange the existing PIN photo diode by a new avalanche photo diode (APD) readout. The newly developed readout electronics will provide an energy resolution compatible to the previous set-up and a fast trigger signal down to 10 MeV energy deposit per crystal. After the successful final tests with a 3x3 CsI crystal matrix in Bonn at ELSA and in Mainz at MAMI all front-end electronics were produced in fall 2013. Automated test routines for the front-end electronics were developed and the characterization measurements of all APDs were successfully accomplished in Bonn. The project is supported by the Deutsche Forschungsgemeinschaft (SFB/TR16) and Schweizerischer Nationalfonds

Studies on multiplication effect of noises of PPDs, and a proposal of a new structure to improve the performance

International Nuclear Information System (INIS)

Oide, H.; Murase, T.; Otono, H.; Yamashita, S.

2010-01-01

Pixelated Photon Detectors (PPDs) are arrayed APDs operated in Geiger-mode. Multi-Pixel Photon Counter (MPPC) is a PPD produced by Hamamatsu Photonics K.K. Test of dark noise rate of a 1600 pixel MPPC as a function of over-voltage at room temperature indicates that the over-voltage is limited up to a few volts because of explosive increase of noise rate. The over-voltage dependence of random noise rate is nevertheless mostly linear. We confirmed this is due to multiplication effect of noises because of after-pulsing and crosstalk. Over-voltage dependence of random noise and photon detection efficiency are qualitatively different. Considering the electric field structure of MPPC (p-on-n type) and Geiger-efficiency as a function of the position of initial pair creation, these characteristics are possible to be understood. One suggestion for p-on-n type PPD from these results is narrowing the depletion layer below the multiplication layer to reduce random noise and after-pulsing. Another proposal is to put additional buffer capacitance parallel to the diode to accomplish higher gain with lower over-voltage simultaneously with lower noise rate.

Studies on multiplication effect of noises of PPDs, and a proposal of a new structure to improve the performance

Energy Technology Data Exchange (ETDEWEB)

Oide, H., E-mail: oide@icepp.s.u-tokyo.ac.j [Department of Physics, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo (Japan); Murase, T.; Otono, H. [Department of Physics, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo (Japan); Yamashita, S. [ICEPP, University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo (Japan)

2010-01-21

Pixelated Photon Detectors (PPDs) are arrayed APDs operated in Geiger-mode. Multi-Pixel Photon Counter (MPPC) is a PPD produced by Hamamatsu Photonics K.K. Test of dark noise rate of a 1600 pixel MPPC as a function of over-voltage at room temperature indicates that the over-voltage is limited up to a few volts because of explosive increase of noise rate. The over-voltage dependence of random noise rate is nevertheless mostly linear. We confirmed this is due to multiplication effect of noises because of after-pulsing and crosstalk. Over-voltage dependence of random noise and photon detection efficiency are qualitatively different. Considering the electric field structure of MPPC (p-on-n type) and Geiger-efficiency as a function of the position of initial pair creation, these characteristics are possible to be understood. One suggestion for p-on-n type PPD from these results is narrowing the depletion layer below the multiplication layer to reduce random noise and after-pulsing. Another proposal is to put additional buffer capacitance parallel to the diode to accomplish higher gain with lower over-voltage simultaneously with lower noise rate.

Geiger counters of gamma rays with a bismuth cathode

International Nuclear Information System (INIS)

Meunier, R.; Legrand, J.P.

1953-01-01

Geiger Muller counters present a lake of efficiency of some per cent, for the γ radiations. In the region 0,3 - 1 MeV, a substantial growth of their output can be obtained by a special construction of their cathode. In accordance with previous works, we constructed some counter of formed cathode by a pleated copper wire fencing covered of Bi by electrolysis. The successive modifications brought to a cylindrical conventional cathode in sheet metal of copper, that succeeds to this type of cathode, drive to an improvement of the output. (M.B.) [fr

Wolfgang Geiger (17 July 1921 - 3 July 2000

Directory of Open Access Journals (Sweden)

Renata Boucher-Rodoni

2000-08-01

Full Text Available Wolfgang Geiger died on the 3rd July 2000, at the age of 79. He was born on July 17th 1921 in Biel; his mother died at his birth. His childhood was spent with his father, a well-known artist, partly in Ligerz, on Lake Biel, and partly in Porto Ronco in Ticino, on Lago Maggiore. After high school in Biel, he began his University studies, first at the Swiss Federal Institute of Technology in Zürich, then in Basel, where he studied under Professor A. Portmann. During his PhD a grant from the Janggen-Pöhn foundation enabled him to work for some months at the Institut des Pêches maritimes du Maroc, in Casablanca, with Dr. J .Furnestin. In 1953 he completed his PhD on teleost fish brain. His career as a biologist began in Bern at the Eidgenossische Inspektion für Fortwesen, Jagd und Fischerei. In 1962 he was appointed head assistant (chef des travaux at the University of Geneva, in the comparative anatomy and physiology laboratory (Dr H. J. Huggel, where he discovered the joys and the limitations of teaching. He was highly regarded as a lecturer and taught in a relaxed atmosphere of mutual respect and trust, much appreciated by his students. Professor Geiger was also the main organiser of field trips to Sète, on the French Mediterranean coast, where he was in his element living on the water. He went out on the trawlers with the students and introduced them enthusiastically to the marvels of sea fauna. He was happy during those field trips and had the knack of communicating his happiness to the students.

Penyusunan Perencanaan Keberlangsungan Bisnis PT PLN (Persero APD Jateng dan DIY dengan ISO 22301 dan Metode OCTAVE

Directory of Open Access Journals (Sweden)

Azmi Afifah Zahra

2017-01-01

Full Text Available Abstrak— Penelitian dalam tugas akhir ini adalah melakukan penyusunan perencanaan keberlangsungan bisnis teknologi informasi pada PT PLN (Persero APD Jateng dan DIY dengan berbasis risiko sebagai bentuk kesiapan perusahaan dalam menangani risiko dan dampak bisnis yang mengancam perusahaan. PT PLN (Persero APD Jateng dan DIY menggunakan sistem dan layanan TI sebagai daya dukung perusahaan dalam mencapai tujuannya. Penggunaan sistem dan layanan TI tersebut tidak terlepas dari adanya ancaman pada risiko sistem dan layanan TI serta dampak dari proses bisnis yang dijalankan oleh tiap fungsi bisnis perusahaan. Dalam proses penyusunan untuk perencanaan keberlangsungan bisnis akan dibuat terlebih dahulu alur kerja untuk kegiatan pengelolaan keberlangsungan bisnis (Business Continuity Management untuk PT PLN (Persero APD Jateng dan DIY dengan menggunakan acuan ISO 22301: 2012 dan alur kerja yang telah diterapkan oleh perusahaan lain yaitu dari Perusahaan Chubu Electric Power Company Group dan DHS Electricity dengan tetap memberikan prosedur praktis yang dapat disesuaikan oleh PT PLN (Persero APD Jateng dan DIY. Hasil akhir dari penelitian ini adalah berupa rekomendasi penerapan alur kerja dan strategi keberlangsungan bisnis untuk PT PLN (Persero berdasarkan pada risiko aset TI yang menjadi tanggung jawab tim SCADA dan Telekomunikasi.

Predictors of Percutaneous Catheter Drainage (PCD) after Abdominal Paracentesis Drainage (APD) in Patients with Moderately Severe or Severe Acute Pancreatitis along with Fluid Collections

Science.gov (United States)

Liu, Wei-hui; Wang, Tao; Yan, Hong-tao; Chen, Tao; Xu, Chuan; Ye, Ping; Zhang, Ning; Liu, Zheng-cai; Tang, Li-jun

2015-01-01

Aims Although we previously demonstrated abdominal paracentesis drainage (APD) preceding percutaneous catheter drainage (PCD) as the central step for treating patients with moderately severe (MSAP) or severe acute pancreatitis (SAP), the predictors leading to PCD after APD have not been studied. Methods Consecutive patients with MSAP or SAP were recruited between June 2011 and June 2013. As a step-up approach, all patients initially received medical management, later underwent ultrasound-guided APD before PCD, if necessary, followed by endoscopic necrosectomy through the path formed by PCD. APD primarily targeted fluid in the abdominal or pelvic cavities, whereas PCD aimed at (peri)pancreatic fluid. Results Of the 92 enrolled patients, 40 were managed with APD alone and 52 received PCD after APD (14 required necrosectomy after initial PCD). The overall mortality was 6.5%. Univariate analysis showed that among the 20 selected parameters, 13 factors significantly affected PCD intervention after APD. Multivariate analysis revealed that infected (peri)pancreatic collections (P = -0.001), maximum extent of necrosis of more than 30% of the pancreas (P = -0.024), size of the largest necrotic peri(pancreatic) collection (P = -0.007), and reduction of (peri)pancreatic fluid collections by collections, a largest necrotic peri(pancreatic) collection of more than 100 ml, and reduction of (peri)pancreatic fluid collections by <50% after APD could effectively predict the need for PCD in the early course of the disease. PMID:25659143

Time over threshold based multi-channel LuAG-APD PET detector

International Nuclear Information System (INIS)

Shimazoe, Kenji; Orita, Tadashi; Nakamura, Yasuaki; Takahashi, Hiroyuki

2013-01-01

To achieve efficient signal processing, several time-based positron emission tomography (PET) systems using a large number of granulated gamma-ray detectors have recently been proposed. In this work described here, a 144-channel Pr:LuAG avalanche photodiode (APD) PET detector that uses time over threshold (ToT) and pulse train methods was designed and fabricated. The detector is composed of 12×12 Pr:LuAG crystals, each of which produces a 2 mm×2 mm×10 mm pixel individually coupled to a 12×12 APD array, which in turn is connected pixel-by-pixel with one channel of a time over threshold based application-specific integrated circuit (ToT-ASIC) that was designed and fabricated using a 0.25 μm 3.3 V Taiwan Semiconductor Company complementary metal oxide semiconductor (TSMC CMOS) process. The ToT outputs are connected through a field-programmable gate array (FPGA) to a data acquisition (DAQ) system. Three front-end ASIC boards—each incorporating a ToT-ASIC chip, threshold control digital-to-analog converters (DACs), and connectors, and dissipating power at about 230 mW per board—are used to read from the 144-channel LuAG-APD detector. All three boards are connected through an FPGA board that is programmed to calibrate the individual thresholds of the ToT circuits to allow digital multiplexing to form an integrated PET module with a measured timing resolution of 4.2 ns. Images transmitted by this PET system can be successfully acquired through collimation masks. As a further implementation of this technology, an animal PET system consisting of eight gamma pixel modules forming a ring is planned

Final report on LDRD project : single-photon-sensitive imaging detector arrays at 1600 nm

International Nuclear Information System (INIS)

Childs, Kenton David; Serkland, Darwin Keith; Geib, Kent Martin; Hawkins, Samuel D.; Carroll, Malcolm S.; Klem, John Frederick; Sheng, Josephine Juin-Jye; Patel, Rupal K.; Bolles, Desta; Bauer, Tom M.; Koudelka, Robert

2006-01-01

The key need that this project has addressed is a short-wave infrared light detector for ranging (LIDAR) imaging at temperatures greater than 100K, as desired by nonproliferation and work for other customers. Several novel device structures to improve avalanche photodiodes (APDs) were fabricated to achieve the desired APD performance. A primary challenge to achieving high sensitivity APDs at 1550 nm is that the small band-gap materials (e.g., InGaAs or Ge) necessary to detect low-energy photons exhibit higher dark counts and higher multiplication noise compared to materials like silicon. To overcome these historical problems APDs were designed and fabricated using separate absorption and multiplication (SAM) regions. The absorption regions used (InGaAs or Ge) to leverage these materials 1550 nm sensitivity. Geiger mode detection was chosen to circumvent gain noise issues in the III-V and Ge multiplication regions, while a novel Ge/Si device was built to examine the utility of transferring photoelectrons in a silicon multiplication region. Silicon is known to have very good analog and GM multiplication properties. The proposed devices represented a high-risk for high-reward approach. Therefore one primary goal of this work was to experimentally resolve uncertainty about the novel APD structures. This work specifically examined three different designs. An InGaAs/InAlAs Geiger mode (GM) structure was proposed for the superior multiplication properties of the InAlAs. The hypothesis to be tested in this structure was whether InAlAs really presented an advantage in GM. A Ge/Si SAM was proposed representing the best possible multiplication material (i.e., silicon), however, significant uncertainty existed about both the Ge material quality and the ability to transfer photoelectrons across the Ge/Si interface. Finally a third pure germanium GM structure was proposed because bulk germanium has been reported to have better dark count properties. However, significant

Final report on LDRD project : single-photon-sensitive imaging detector arrays at 1600 nm.

Energy Technology Data Exchange (ETDEWEB)

Childs, Kenton David; Serkland, Darwin Keith; Geib, Kent Martin; Hawkins, Samuel D.; Carroll, Malcolm S.; Klem, John Frederick; Sheng, Josephine Juin-Jye; Patel, Rupal K.; Bolles, Desta; Bauer, Tom M.; Koudelka, Robert

2006-11-01

The key need that this project has addressed is a short-wave infrared light detector for ranging (LIDAR) imaging at temperatures greater than 100K, as desired by nonproliferation and work for other customers. Several novel device structures to improve avalanche photodiodes (APDs) were fabricated to achieve the desired APD performance. A primary challenge to achieving high sensitivity APDs at 1550 nm is that the small band-gap materials (e.g., InGaAs or Ge) necessary to detect low-energy photons exhibit higher dark counts and higher multiplication noise compared to materials like silicon. To overcome these historical problems APDs were designed and fabricated using separate absorption and multiplication (SAM) regions. The absorption regions used (InGaAs or Ge) to leverage these materials 1550 nm sensitivity. Geiger mode detection was chosen to circumvent gain noise issues in the III-V and Ge multiplication regions, while a novel Ge/Si device was built to examine the utility of transferring photoelectrons in a silicon multiplication region. Silicon is known to have very good analog and GM multiplication properties. The proposed devices represented a high-risk for high-reward approach. Therefore one primary goal of this work was to experimentally resolve uncertainty about the novel APD structures. This work specifically examined three different designs. An InGaAs/InAlAs Geiger mode (GM) structure was proposed for the superior multiplication properties of the InAlAs. The hypothesis to be tested in this structure was whether InAlAs really presented an advantage in GM. A Ge/Si SAM was proposed representing the best possible multiplication material (i.e., silicon), however, significant uncertainty existed about both the Ge material quality and the ability to transfer photoelectrons across the Ge/Si interface. Finally a third pure germanium GM structure was proposed because bulk germanium has been reported to have better dark count properties. However, significant

Sci-Sat AM(1): Imaging-08: Small animal APD PET detector with submillimetric resolution for molecular imaging.

Science.gov (United States)

Bérard, P; Bergeron, M; Pepin, C M; Cadorette, J; Tétrault, M-A; Viscogliosi, N; Fontaine, R; Dautet, H; Davies, M; Lecomte, R

2008-07-01

Visualization and quantification of biological processes in mice, the preferred animal model in most preclinical studies, require the best possible spatial resolution in positron emission tomography (PET). A new 64-channel avalanche photodiode (APD) detector module was developed to achieve submillimeter spatial resolution for this purpose. The module consists of dual 4 × 8 APD arrays mounted in a custom ceramic holder. Individual APD pixels having an active area of 1.1 × 1.1 mm2 at a 1.2 mm pitch can be fitted to an 8 × 8 LYSO scintillator block designed to accommodate one-to-one coupling. An analog test board with four 16-channel preamplifier ASICs was designed to be interfaced with the existing LabPET digital processing electronics. At a standard APD operating bias, a mean energy resolution of 27.5 ± 0.6% was typically obtained at 511 keV with a relative standard deviation of 13.8% in signal amplitude for the 64 individual pixels. Crosstalk between pixels was found to be well below the typical lower energy threshold used for PET imaging applications. With two modules in coincidence, a global timing resolution of 5.0 ns FWHM was measured. Finally, an intrinsic spatial resolution of 0.8 mm FWHM was measured by sweeping a 22Na point source between two detector arrays. The proposed detector module demonstrates promising characteristics for dedicated mouse PET imaging at submillimiter resolution. © 2008 American Association of Physicists in Medicine.

Construction techniques and working principles of external cathode Geiger-Mueller counters

International Nuclear Information System (INIS)

Sevegnani, Francisco Xavier

1996-01-01

In this paper, the construction technique and working principles of the external cathode Geiger-Mueller counter are described in detail. During the analysis of the behavior of these counters a new phenomena was observed, related to an increase int he background rate with the applied voltage. The experiments have also shown that the pulse amplitude of those counters decreases exponentially with the counting rate. The counters built with the techniques described in this paper has shown plateaus of about 1400 V with slope of 0,8%/100 V. (author)

Performance Analysis of OCDMA Based on AND Detection in FTTH Access Network Using PIN & APD Photodiodes

Science.gov (United States)

Aldouri, Muthana; Aljunid, S. A.; Ahmad, R. Badlishah; Fadhil, Hilal A.

2011-06-01

In order to comprise between PIN photo detector and avalanche photodiodes in a system used double weight (DW) code to be a performance of the optical spectrum CDMA in FTTH network with point-to-multi-point (P2MP) application. The performance of PIN against APD is compared through simulation by using opt system software version 7. In this paper we used two networks designed as follows one used PIN photo detector and the second using APD photo diode, both two system using with and without erbium doped fiber amplifier (EDFA). It is found that APD photo diode in this system is better than PIN photo detector for all simulation results. The conversion used a Mach-Zehnder interferometer (MZI) wavelength converter. Also we are study, the proposing a detection scheme known as AND subtraction detection technique implemented with fiber Bragg Grating (FBG) act as encoder and decoder. This FBG is used to encode and decode the spectral amplitude coding namely double weight (DW) code in Optical Code Division Multiple Access (OCDMA). The performances are characterized through bit error rate (BER) and bit rate (BR) also the received power at various bit rate.

The AX-PET demonstrator-Design, construction and characterization

International Nuclear Information System (INIS)

Beltrame, P.; Bolle, E.; Braem, A.; Casella, C.; Chesi, E.; Clinthorne, N.; De Leo, R.; Dissertori, G.; Djambazov, L.; Fanti, V.; Heller, M.; Joram, C.; Kagan, H.; Lustermann, W.; Meddi, F.; Nappi, E.; Nessi-Tedaldi, F.; Oliver, J.F.; Pauss, F.; Rafecas, M.

2011-01-01

Axial PET is a novel geometrical concept for Positron Emission Tomography (PET), based on layers of long scintillating crystals axially aligned with the bore axis. The axial coordinate is obtained from arrays of wavelength shifting (WLS) plastic strips placed orthogonally to the crystals. This article describes the design, construction and performance evaluation of a demonstrator set-up which consists of two identical detector modules, used in coincidence. Each module comprises 48 LYSO crystals of 100 mm length and 156 WLS strips. Crystals and strips are readout by Geiger-mode Avalanche Photo Diodes (G-APDs). The signals from the two modules are processed by fully analog front-end electronics and recorded in coincidence by a VME-based data acquisition system. Measurements with point-like 22 Na sources, with the modules used both individually and in coincidence mode, allowed for a complete performance evaluation up to the focal plane reconstruction of point sources. The results obtained are in good agreement with expectations and proved the set-up to be ready for the next evaluation phase with PET phantoms filled with radiotracers.

Current 2-μm dial measurements of atmospheric CO2 and expected results from space using new MCT APDS

Science.gov (United States)

Dumas, A.; Gibert, F.; Rothman, J.; Édouart, D.; Le Mounier, F.; Cénac, C.

2017-11-01

In the framework of CO2 monitoring in the Atmospheric Boundary Layer (ABL), a ground-based 2-μm Differential Absorption Lidar (DIAL) has been developed at the Laboratoire de Météorologie Dynamique (LMD) in Palaiseau. In order to derive flux information, this system has been set up with coherent detection, which allows to combine CO2 density measurements with wind velocity measurements. On the other hand, new advances in the field of Mercury Cadmium Tellure (MCT) Avalanche Photodiodes (APDs) open the way for high-precision measurements in direct detection ultimately from space. In this study, we first report on state of the art measurements obtained with the current coherent DIAL system before presenting expected results for a similar laser transmitter equipped with MCT APDs. For this latter part, we use a numerical model which relies on APDs performance data provided by the Laboratoire d'Électronique et de Technologie de l'Information (LETI).

Cosmic rays with portable Geiger counters: from sea level to airplane cruise altitudes

Energy Technology Data Exchange (ETDEWEB)

Blanco, Francesco; La Rocca, Paola; Riggi, Francesco [Department of Physics and Astronomy, University of Catania, Via S. Sofia 64, I-95123 Catania (Italy)], E-mail: Francesco.Riggi@ct.infn.it

2009-07-15

Cosmic ray count rates with a set of portable Geiger counters were measured at different altitudes on the way to a mountain top and aboard an aircraft, between sea level and cruise altitude. Basic measurements may constitute an educational activity even with high school teams. For the understanding of the results obtained, simulations of extensive air showers induced by high-energy primary protons in the atmosphere were also carried out, involving undergraduate and graduate teaching levels.

Experimental characterization of the 192 channel Clear-PEM frontend ASIC coupled to a multi-pixel APD readout of LYSO:Ce crystals

International Nuclear Information System (INIS)

Albuquerque, Edgar; Bexiga, Vasco; Bugalho, Ricardo; Carrico, Bruno; Ferreira, Claudia S.; Ferreira, Miguel; Godinho, Joaquim; Goncalves, Fernando; Leong, Carlos; Lousa, Pedro; Machado, Pedro; Moura, Rui; Neves, Pedro; Ortigao, Catarina; Piedade, Fernando; Pinheiro, Joao F.; Rego, Joel; Rivetti, Angelo; Rodrigues, Pedro; Silva, Jose C.

2009-01-01

In the framework of the Clear-PEM project for the construction of a high-resolution scanner for breast cancer imaging, a very compact and dense frontend electronics system has been developed for readout of multi-pixel S8550 Hamamatsu APDs. The frontend electronics are instrumented with a mixed-signal Application-Specific Integrated Circuit (ASIC), which incorporates 192 low-noise charge pre-amplifiers, shapers, analog memory cells and digital control blocks. Pulses are continuously stored in memory cells at clock frequency. Channels above a common threshold voltage are readout for digitization by off-chip free-sampling ADCs. The ASIC has a size of 7.3x9.8mm 2 and was implemented in a AMS 0.35μm CMOS technology. In this paper the experimental characterization of the Clear-PEM frontend ASIC, reading out multi-pixel APDs coupled to LYSO:Ce crystal matrices, is presented. The chips were mounted on a custom test board connected to six APD arrays and to the data acquisition system. Six 32-pixel LYSO:Ce crystal matrices coupled on both sides to APD arrays were readout by two test boards. All 384 channels were operational. The chip power consumption is 660 mW (3.4 mW per channel). A very stable behavior of the chip was observed, with an estimated ENC of 1200-1300e - at APD gain 100. The inter-channel noise dispersion and mean baseline variation is less than 8% and 0.5%, respectively. The spread in the gain between different channels is found to be 1.5%. Energy resolution of 16.5% at 511 keV and 12.8% at 662 keV has been measured. Timing measurements between the two APDs that readout the same crystal is extracted and compared with detailed Monte Carlo simulations. At 511 keV the measured single photon time RMS resolution is 1.30 ns, in very good agreement with the expected value of 1.34 ns.

Kepatuhan Menggunakan Alat Pelindung Diri (APD Ditinjau dari Pengetahuan dan Perilaku pada Petugas Instalasi Pemeliharaan Sarana Dan Prasarana Rumah Sakit (IPSRS.

Directory of Open Access Journals (Sweden)

Rizka Ayu Zahara

2017-12-01

Full Text Available Abstrak: Alat Pelindung Diri (APD berfungsi untuk melindungi tubuh terhadap bahaya-bahaya kecelakaan kerja dan mengurangi tingkat keparahan dari kecelakaan kerja yang terjadi. Penelitian ini bertujuan untuk mengetahui korelasi antara pengetahuan dan perilaku petugas Instalasi Pemeliharaan Sarana dan Prasarana Rumah Sakit (IPSRS dengan kepatuhan terhadap penggunaan Alat Pelindung Diri (APD. Desain penelitian ini adalah Cross Sectional. Populasi adalah seluruh petugas IPSRS di RSUD Siti Aisyah Kota Lubuklinggau sebanyak 64 orang. Penelitian dilaksanakan pada bulan Agustus 2017. Analisis data menggunakan uji statistik chi-Square. Hasil penelitian menunjukkan adanya korelasi antara kepatuhan menggunakan Alat Pelindung Diri APD pengetahuan (p value = 0, 001, dan perilaku (p value = 0, 006. Pihak RSUD diharapkan dapat menerapkan Standar Prosedur Operasional (SPO yang lebih tegas, melakukan pelatihan tentang penggunaan APD, dan meningkatkan pengawasan terhadap kepatuhan petugas dalam menggunakan APD. Kata Kunci : Pengetahuan, Perilaku, Kepatuhan Alat Pelindung Diri (APD. ADHERENCE USING PERSONAL PROTECTIVE EQUIPMENT (PPE IN TERMS OF THE KNOWLEDGE AND BEHAVIOR OF OFFICER INSTALLATION MAINTENANCE FACILITIES AND INFRASTRUCTURE HOSPITAL (IPSRS Abstract: Personal Protective Equipment (PPE serves to protect the body against occupational injuries and reduce the severity of work accidents that occur. This study aims to determine the correlation between the knowledge and behavior of the officer of the Installation of Hospital Facilities and Infrastructure Maintenance (IPSRS with the adherence to the use of Personal Protective Equipment (PPE. The design of this study was Cross Sectional. The population is all IPSRS officers in RSUD Siti Aisyah Lubuklinggau City as many as 64 people. The study was conducted in August 2017. The data analysis used chi-square statistical test. The results showed that there was a correlation between adherence using Personal

Radiation level measured by a portable Geiger-Mueller counter at the altitude of commercial air routes

International Nuclear Information System (INIS)

Araki, Takashi

1995-01-01

The background intensities of naturally occurring radiation were measured aboard scheduled commercial airplanes using a newly developed Geiger-Mueller counter with a pocket computer. The preliminary results show that the radiation at the cruising altitude of a commercial airplane on a transcontinental flight is 40 times higher than the ground-level. (author)

Geiger-Mueller haloid counter dead time dependence on counting rate

International Nuclear Information System (INIS)

Onishchenko, A.M.; Tsvetkov, A.A.

1980-01-01

The experimental dependences of the dead time of Geiger counters (SBM-19, SBM-20, SBM-21 and SGM-19) on the loading, are presented. The method of two sources has been used to determine the dead time counters of increased stability. The counters are switched on according to the usually used circuit of discrete counting with loading resistance of 50 MOhm and the separating capacity of 10 pF. Voltage pulses are given to the counting device with the time of resolution of 100 ns, discrimenation threshold 3 V, input resistance 3.6 Ω and the input capacity-15 pF. The time constant of the counter RC-circuit is 50 μs

Amplitude and timing properties of a Geiger discharge in a SiPM cell

Energy Technology Data Exchange (ETDEWEB)

Popova, E., E-mail: elenap73@mail.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Kashirskoe Shosse 31 (Russian Federation); Buzhan, P.; Pleshko, A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Kashirskoe Shosse 31 (Russian Federation); Vinogradov, S. [University of Liverpool and Cockcroft Institute, Sci-Tech Daresbury, Keckwick Lane, Warrington WA4 4AD, Cheshire (United Kingdom); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Leninskiy Prospect 53, Moscow 119991 (Russian Federation); Stifutkin, A.; Ilyin, A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Kashirskoe Shosse 31 (Russian Federation); Besson, D. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 115409, Kashirskoe Shosse 31 (Russian Federation); Department of Physics and Astronomy, University of Kansas, Lawrence, KS 66045-2151 (United States); Mirzoyan, R. [Max-Planck-Institute for Physics, Föhringer Ring 6, 80805 München (Germany)

2015-07-01

The amplitude and timing properties of a Geiger discharge in a stand-alone SiPM cell have been investigated in detail. Use of a single stand-alone SiPM cell allows us to perform measurements with better accuracy than the multicell structure of conventional SiPMs. We have studied the dependence of the output charge and amplitude from an SiPM cell illuminated by focused light vs the number of primary photoelectrons. We propose a SPICE model which explains the amplitude over saturation (when the SiPM's amplitude is greater than the sum over all cells) characteristics of SiPM signals for more than one initial photoelectrons. The time resolutions of a SiPM cell have been measured for the case of single (SPTR) and multiphoton light pulses. The Full Width Half Max (FWHM) for SPTR has been found to be at the level of 30 ps for focused and 40 ps for unfocused light (100 μm cell size). - Highlights: • A stand-alone SiPM cell has been investigated in detail. • Amplitude and time properties have been measured with femtosecond 660 nm laser. • SPICE model for a Geiger discharge development has been proposed. • SPTR for a stand-alone 100 μm size SiPM cell has been found to be 40 ps FWHM.

Construction and operating characteristics of flexible Geiger counters; Caracteristiques de construction et d'utilisation de compteurs Geiger flexibles; Konstruktsionnaya i operativnaya kharakteristiki gibkikh schetchikov Gejgera; Construccion y caracteristicas de funcionamiento de contadores Geiger flexibles

Energy Technology Data Exchange (ETDEWEB)

Richter, H G; Ballard, L F [Research Triangle Institute, Durham, NC (United States)

1962-04-15

point une methode de construction de compteurs Geiger flexibles ayant des dimensions tres variees. Les compteurs sont tres flexibles : un compteur de 3 cm de diametre peut etre plie avec un rayon de courbure de 5 cm. En utilisant du gaz Q (98,3% d'helium et 1,7% de n-butane) comme milieu de comptage, les paliers ont une longueur de plusieurs centaines de volts avec une pente de 3% et sont independants de la configuration geometrique du compteur. Les compteurs sont construits avec des tubes en chlorure de polyvinyle (PVC-744 - Alpha Wire Corp.). De courts segments du tube (longueur egale a environ 3 fois le diametre) sont glisses sur un mandrin d'aluminium grossierement filete et entoures d'un fil fortement serre. Le tout est place dans un four a 110{sup o}C pendant 20 minutes. Apres refroidissement, le segment de matiere plastique ainsi cannele est degage du mandrin. Ce traitement du tube empeche sa rupture lorsqu'il est enroule. Un disque de polystyrene, perfore de trous relativement grands a la peripherie pour l'ecoulement du gaz et d'un trou central de 0,6 mm pour le passage de l'anode, est attache a une extremite de chaque segment. En enfilant les segments ainsi prepares sur une anode en tungstene de 3 mm, en glissant une extremite de chaque segment sur le segment adjacent et en les fixant solidement avec un adhesif, on peut construire un compteur d'une longueur quelconque. On attache aux extremites des pieces en verre pour la fixation de l'anode et pour l'admission et l'evacuation du gaz. Un fil de cuivre nu, entoure en spirale dans les cannelures du compteur, donne une cathode externe satisfaisante, qui fonctionne suivant le mode observe par Maze. Un compteur de 3 cm de diametre et de 1 metre de longueur, lineaire ou enroule, possede un palier commencant a 1400 volts et allant jusqu'a 1700 volts avec une pente de 2,9%. On a enregistre des taux de comptage de plus de 300000 coups par minute, avec peu de pertes par coincidences. Comme le compteur est en fait une

Fine-grained hodoscopes based on scintillating optical fibers

International Nuclear Information System (INIS)

Borenstein, S.R.; Strand, R.C.

1981-01-01

In order to exploit the high event rates at ISABELLE, it will be necessary to have fast detection with fine spatial resolution. The authors are currently constructing a prototype fine-grained hodoscope, the elements of which are scintillating optical fibers. The fibers have been drawn from commercially available plastic scintillator which has been clad with a thin layer of silicone. So far it has been demonstrated with one mm diameter fibers, that with a photodetector at each end, the fibers are more than 99% efficient for lengths of about 60 cm. The readout will be accomplished either with small diameter photomultiplier tubes or avalanche photodiodes used either in the linear or Geiger mode. The program of fiber development and evaluation is described. The status of the APD as a readout element is discussed, and an optical encoding readout scheme is described for events of low multiplicity

Hydrological Climate Classification: Can We Improve on Köppen-Geiger?

Science.gov (United States)

Knoben, W.; Woods, R. A.; Freer, J. E.

2017-12-01

Classification is essential in the study of complex natural systems, yet hydrology so far has no formal way to structure the climate forcing which underlies hydrologic response. Various climate classification systems can be borrowed from other disciplines but these are based on different organizing principles than a hydrological classification might use. From gridded global data we calculate a gridded aridity index, an aridity seasonality index and a rain-vs-snow index, which we use to cluster global locations into climate groups. We then define the membership degree of nearly 1100 catchments to each of our climate groups based on each catchment's climate and investigate the extent to which streamflow responses within each climate group are similar. We compare this climate classification approach with the often-used Köppen-Geiger classification, using statistical tests based on streamflow signature values. We find that three climate indices are sufficient to distinguish 18 different climate types world-wide. Climates tend to change gradually in space and catchments can thus belong to multiple climate groups, albeit with different degrees of membership. Streamflow responses within a climate group tend to be similar, regardless of the catchments' geographical proximity. A Wilcoxon two-sample test based on streamflow signature values for each climate group shows that the new classification can distinguish different flow regimes using this classification scheme. The Köppen-Geiger approach uses 29 climate classes but is less able to differentiate streamflow regimes. Climate forcing exerts a strong control on typical hydrologic response and both change gradually in space. This makes arbitrary hard boundaries in any classification scheme difficult to defend. Any hydrological classification should thus acknowledge these gradual changes in forcing. Catchment characteristics (soil or vegetation type, land use, etc) can vary more quickly in space than climate does, which

Studies on an automated gain stabilisation for the new APD read-out of the crystal barrel calorimeter

Energy Technology Data Exchange (ETDEWEB)

Pauli, Peter [HISKP Bonn (Germany); Collaboration: CBELSA/TAPS-Collaboration

2016-07-01

For the investigation of the nucleon spectrum it is not enough to measure only cross sections because of the large overlap of resonances. To disentangle these resonances, a partial wave analysis is needed. To find unambiguous solutions it is necessary to measure (double) polarisation observables. The CBELSA/TAPS experiment is an important tool to measure these observables in meson photoproduction off nucleons. To achieve a high efficiency in purely neutral reactions it is important to implement the main calorimeter into the first level trigger. To do so it is necessary to replace the current PIN photo diodes with new avalanche photo diodes (APDs). The new read-out is able to provide a timing signal that is fast enough to use it as a trigger while it does not impair the energy resolution of the calorimeter compared to the previous system. A drawback of APDs is their temperature dependency. To provide a stable gain throughout varying running conditions it is vital to monitor the temperature change and correct it if necessary. The poster shows an approach to ensure temperature stability where the temperature is monitored via a temperature sensitive NTC thermistor and the gain is adjusted via changes of the high voltage supply of the APDs. This method proved successful while it is easy to implement in all 1320 CsI(Tl) crystals of the calorimeter.

APD Response Time Measurements for Future TOF-E Systems

Science.gov (United States)

Starkey, M. J.; Ogasawara, K.; Dayeh, M. A.; Desai, M. I.

2017-12-01

In space physics, the ability to detect ions is crucial to understanding plasma distributions in the solar wind. This usually typically requires the determination of the particle's mass, charge, and total energy. Current ion detection schemes are implemented in three sequential parts; an electrostatic analyzer for energy per charge (E/Q) measurements, a time-of-flight (TOF) for mass per charge (M/Q) measurements, and a solid-state detector (SSD) for total energy (E) measurements. Recent work has suggested the use of avalanche photodiode detectors (APD) for a simultaneous TOF and total energy (TOF-E) measurement system, which would replace traditional SSDs, simplify design, and reduce costs. Although TOF based ion spectrometry typically requires timing resolution of systems.

Geiger Muller (GM) detector as online monitor: an experimental study

International Nuclear Information System (INIS)

Jayan, M.P.; Pawar, V.J.; Krishnakumar, P.; Sureshkumar, M.

2014-01-01

Monitoring the inadvertent release of radioactivity into otherwise inactive liquid streams is a common requirement in nuclear industry. In addition to conventional off-line sampling and measurement methods, nuclear facilities usually uses online methods to get real-time detection of activity contents in process cooling water lines and steam condensate lines. Due to its simplicity, ruggedness and cost effectiveness, Geiger Muller counter is obviously the first choice for online application. Though GM based monitors for such online application were in industrial use for a long time, practical data on the response of the detector with respect low level activities in the effluents is scarce in literature. This work was carried out to fill this information gap. The data generated in these experiments may be useful in giving a realistic interpretation of the response of the existing monitors and setting up their alarm limits

Potassium analysis by beta counting using a Geiger-Mueller system

International Nuclear Information System (INIS)

Espana, E.; Beneitez, P.; Calderon, T.

1993-01-01

A technique for quantitative analysis of different soils, ceramics, feldspars and natural halide samples is presented, based on the measurement of β-activities using a Geiger-Mueller system. The system was calibrated with KCl, KC 8 H 5 O 4 , KNO 3 and K 2 SO 4 standards and a potassium content of 1% yields a net β-count rate (background subtracted) of about 55 cph. Precision values of less than ±0.4% K can be achieved in counting times of about 4 hours. The results agree with those obtained by means of other more common analytical methods such as flame photometry, atomic absorption and γ-spectrometry. In comparison with these methods, this approach is direct, precise and non-destructive, because the samples do not require prior treatment. (author) 16 refs.; 2 figs.; 6 tabs

Das Thema “Altern” in Arno Geigers Roman «Alles über Sally»

Directory of Open Access Journals (Sweden)

Meike Dackweiler

2013-11-01

Full Text Available Alles über Sally (All about Sally is the fifth novel of the successful Austrian author Arno Geiger. While it was both praised and criticized for being a contemporary adaption of the adultery novel, little importance was attached to the theme of ageing, which pervades the whole novel. Moreover, adulterous female characters over fifty are rare in contemporary German literature. Given these premises, this essay examines the composition of the ageing characters in the novel and provides a discussion of the social construction of images of ageing.

On-chip integrated functional near infra-red spectroscopy (fNIRS) photoreceiver for portable brain imaging

Science.gov (United States)

Kamrani, Ehsan

Optical brain imaging using functional near infra-red spectroscopy (fNIRS) offers a direct and noninvasive tool for monitoring of blood oxygenation. fNIRS is a noninvasive, safe, minimally intrusive, and high temporal-resolution technique for real-time and long-term brain imaging. It allows detecting both fast-neuronal and slow-hemodynamic signals. Besides the significant advantages of fNIRS systems, they still suffer from few drawbacks including low spatial-resolution, moderately high-level noise and high-sensitivity to movement. In order to overcome the limitations of currently available non-portable fNIRS systems, we have introduced a new low-power, miniaturized on-chip photodetector front-end intended for portable fNIRS systems. It includes silicon avalanche photodiode (SiAPD), Transimpedance amplifier (TIA), and Quench- Reset circuitry implemented using standard CMOS technologies to operate in both linear and Geiger modes. So it can be applied for both continuous-wave fNIRS (CW-fNIRS) and also single-photon counting applications. Several SiAPDs have been implemented in novel structures and shapes (Rectangular, Octagonal, Dual, Nested, Netted, Quadratic and Hexadecagonal) using different premature edge breakdown prevention techniques. The main characteristics of the SiAPDs are validated and the impact of each parameter and the device simulators (TCAD, COMSOL, etc.) have been studied based on the simulation and measurement results. Proposed techniques exhibit SiAPDs with high avalanche-gain (up to 119), low breakdown-voltage (around 12V) and high photon-detection efficiency (up to 72% in NIR region) in additional to a low dark-count rate (down to 30Hz at 1V excess bias voltage). Three new high gain-bandwidth product (GBW) and low-noise TIAs are introduced and implemented based on distributed-gain concept, logarithmic-amplification and automatic noise-rejection and have been applied in linear-mode of operation. The implemented TIAs offer a power

Pixel multiplexing technique for real-time three-dimensional-imaging laser detection and ranging system using four linear-mode avalanche photodiodes

Energy Technology Data Exchange (ETDEWEB)

Xu, Fan; Wang, Yuanqing, E-mail: yqwang@nju.edu.cn; Li, Fenfang [School of Electronic Science and Engineering, Nanjing University, Nanjing 210046 (China)

2016-03-15

The avalanche-photodiode-array (APD-array) laser detection and ranging (LADAR) system has been continually developed owing to its superiority of nonscanning, large field of view, high sensitivity, and high precision. However, how to achieve higher-efficient detection and better integration of the LADAR system for real-time three-dimensional (3D) imaging continues to be a problem. In this study, a novel LADAR system using four linear mode APDs (LmAPDs) is developed for high-efficient detection by adopting a modulation and multiplexing technique. Furthermore, an automatic control system for the array LADAR system is proposed and designed by applying the virtual instrumentation technique. The control system aims to achieve four functions: synchronization of laser emission and rotating platform, multi-channel synchronous data acquisition, real-time Ethernet upper monitoring, and real-time signal processing and 3D visualization. The structure and principle of the complete system are described in the paper. The experimental results demonstrate that the LADAR system is capable of achieving real-time 3D imaging on an omnidirectional rotating platform under the control of the virtual instrumentation system. The automatic imaging LADAR system utilized only 4 LmAPDs to achieve 256-pixel-per-frame detection with by employing 64-bit demodulator. Moreover, the lateral resolution is ∼15 cm and range accuracy is ∼4 cm root-mean-square error at a distance of ∼40 m.

Ultrafast photon number resolving detector with a temperature stabilized si multi pixel photon counter

International Nuclear Information System (INIS)

Song, Minsoo; Hong, Eugene; Won, Eunil; Yoon, Tai Hyun

2008-01-01

Quantum information science has been rapidly progressed and matured and matured thanks to the recent developments of the single photon detection technologies. Single photon detectors such as a Si avalanche photo diode(APD)in the infrared, an InGaAs/InP APD in the telecommunication band, and a super conducting transient edge sensor(TES)in the broad region of the spectrum have been widely used. Single photon detectors, however, operating at the ultraviolet to visible (370nm∼800nm)regions has not been actively investigated partly due to the lack of single photon and/or entangled photon sources and the lack of solid state single photon detectors. In this paper, we investigate the single photon detection characteristics of a Si multi pixel photon counter(MPPC), which has a high spectral responsivity between 300nm to 800nm, as a photon number resolving solid state detector. Figure 1 shows the schematic diagram of the single photon detection set up at 399nm by using a temperature stabilized Si MPPC. The output beam of the laser being properly attenuated is directed to the MPPC module, at which fixed number of photo electrons corresponding to incident individual photon are generated at Geiger mode of the Si APD pixels. The detected photo current is converted into a digital signal by using a fast analog to digital converter and a digital oscilloscope stores the time sequence of the photo currents. Figure 2 shows the accumulated charges collected by MPPC at∼10.deg.C showing a clear single photon and two photons peaks, respectively, separated by ∼5 sigma of the coincidence counts at the two output ports of a Mach Zender interferometer as a function of optical path length difference. The research was supported by Seoul R and BD program(NT070127)and by the KRISS

Ultrafast photon number resolving detector with a temperature stabilized si multi pixel photon counter

Energy Technology Data Exchange (ETDEWEB)

Song, Minsoo; Hong, Eugene; Won, Eunil; Yoon, Tai Hyun [Korea Univ., Seoul (Korea, Republic of)

2008-11-15

Quantum information science has been rapidly progressed and matured and matured thanks to the recent developments of the single photon detection technologies. Single photon detectors such as a Si avalanche photo diode(APD)in the infrared, an InGaAs/InP APD in the telecommunication band, and a super conducting transient edge sensor(TES)in the broad region of the spectrum have been widely used. Single photon detectors, however, operating at the ultraviolet to visible (370nm∼800nm)regions has not been actively investigated partly due to the lack of single photon and/or entangled photon sources and the lack of solid state single photon detectors. In this paper, we investigate the single photon detection characteristics of a Si multi pixel photon counter(MPPC), which has a high spectral responsivity between 300nm to 800nm, as a photon number resolving solid state detector. Figure 1 shows the schematic diagram of the single photon detection set up at 399nm by using a temperature stabilized Si MPPC. The output beam of the laser being properly attenuated is directed to the MPPC module, at which fixed number of photo electrons corresponding to incident individual photon are generated at Geiger mode of the Si APD pixels. The detected photo current is converted into a digital signal by using a fast analog to digital converter and a digital oscilloscope stores the time sequence of the photo currents. Figure 2 shows the accumulated charges collected by MPPC at∼10.deg.C showing a clear single photon and two photons peaks, respectively, separated by ∼5 sigma of the coincidence counts at the two output ports of a Mach Zender interferometer as a function of optical path length difference. The research was supported by Seoul R and BD program(NT070127)and by the KRISS.

Geiger-Nuttall Law for Nuclei in Strong Electromagnetic Fields

Science.gov (United States)

Delion, D. S.; Ghinescu, S. A.

2017-11-01

We investigate the influence of a strong laser electromagnetic field on the α -decay rate by using the Hennenberger frame of reference. We introduce an adimensional parameter D =S0/R0, where R0 is the geometrical nuclear radius and S0˜√{I }/ω2 is a length parameter depending on the laser intensity I and frequency ω . We show that the barrier penetrability has a strong increase for intensities corresponding to D >Dcrit=1 , due to the fact that the resulting Coulomb potential becomes strongly anisotropic even for spherical nuclei. As a consequence, the contribution of the monopole term increases the barrier penetrability by 2 orders of magnitude, while the total contribution has an effect of 6 orders of magnitude at D ˜3 Dcrit. In the case of deformed nuclei, the electromagnetic field increases the penetrability by an additional order of magnitude for a quadrupole deformation β2˜0.3 . The influence of the electromagnetic field can be expressed in terms of a shifted Geiger-Nuttal law by a term depending on S0 and deformation.

FACT. New image parameters based on the watershed-algorithm

Energy Technology Data Exchange (ETDEWEB)

Linhoff, Lena; Bruegge, Kai Arno; Buss, Jens [TU Dortmund (Germany). Experimentelle Physik 5b; Collaboration: FACT-Collaboration

2016-07-01

FACT, the First G-APD Cherenkov Telescope, is the first imaging atmospheric Cherenkov telescope that is using Geiger-mode avalanche photodiodes (G-APDs) as photo sensors. The raw data produced by this telescope are processed in an analysis chain, which leads to a classification of the primary particle that induce a shower and to an estimation of its energy. One important step in this analysis chain is the parameter extraction from shower images. By the application of a watershed algorithm to the camera image, new parameters are computed. Perceiving the brightness of a pixel as height, a set of pixels can be seen as 'landscape' with hills and valleys. A watershed algorithm groups all pixels to a cluster that belongs to the same hill. From the emerging segmented image, one can find new parameters for later analysis steps, e.g. number of clusters, their shape and containing photon charge. For FACT data, the FellWalker algorithm was chosen from the class of watershed algorithms, because it was designed to work on discrete distributions, in this case the pixels of a camera image. The FellWalker algorithm is implemented in FACT-tools, which provides the low level analysis framework for FACT. This talk will focus on the computation of new, FellWalker based, image parameters, which can be used for the gamma-hadron separation. Additionally, their distributions concerning real and Monte Carlo Data are compared.

PEP-4 geiger-mode hexagonal calorimeter

International Nuclear Information System (INIS)

Wenzel, W.A.

1982-01-01

The design and performance of the calorimeter are briefly described. Design aspects include illustrations of the active volume of the detector, edge connections, module assembly and analog electronics. Performance data for cosmic rays and radiation sources, including efficiency and channel sensitivity are discussed

The roles played by the Canadian General Electric Company's Atomic Power Department in Canada's nuclear power program: work, organization and success in APD, 1955-1995

International Nuclear Information System (INIS)

Cantello, G.W.

2003-01-01

This thesis explores the roles played by the Canadian General Electric Company's Atomic Power Department (APD) in Canada's distinctive nuclear power program. From the establishment of APD in 1955 until the completion of the KANUPP project in Pakistan in 1972, the company's strategy encompassed the design, manufacture, and commissioning of entire nuclear power projects in Canada and abroad. APD then developed a specialized role in the design and supply of complete nuclear fuel handling systems, nuclear fuel bundles, and service work, that sustained a thriving workplace. Five key factors are identified as the reasons behind the long and successful history of the department: (1) Strong, capable and efficient management from the start, (2) Flexible organizational structure, (3) Extremely competent design group, (4) Excellent manufacturing, test, commissioning and service capabilities, (5) Correctly identifying, at the right time, the best fields in which to specialize. (author)

Radiological manifestations of biphosphonate treatment with APD in a child suffering from osteogenesis imperfecta

Energy Technology Data Exchange (ETDEWEB)

Devogelaer, J.P.; Deuxchaisnes, C.N. de; Malghem, J.; Maldague, B.

1987-07-01

A 12-year-old female suffering fromosteogenesis imperfecta (OI) was treated with 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) orally, 250 mg daily, for periods of 2 months, alternating with periods of 2 months of abstinence. Total duration of therapy was 1 year. Radiological and clinical improvement was striking. Furthermore, X-rays of the bones showed large, parallel radio-opaque striae, corresponding exactly to the periods of therapy. These were present in all metaphyses.

A prospective, randomized multicenter study comparing APD and CAPD treatment

DEFF Research Database (Denmark)

Bro, S; Bjorner, J B; Tofte-Jensen, P

2000-01-01

, dialysis-related complications, dialysis-related expenses. RESULTS: The quality-of-life studies showed that significantly more time for work, family, and social activities was available to patients on APD compared to those on CAPD (p ...) treatment with respect to quality of life and clinical outcomes in relation to therapy costs. DESIGN: A prospective, randomized multicenter study. SETTING: Three Danish CAPD units. PATIENTS: Thirty-four adequately dialyzed patients with high or high-average peritoneal transport characteristics were included...... were assessed at baseline and after 6 months by the self-administered short-form SF-36 generic health survey questionnaire supplemented with disease- and treatment-specific questions. Therapy costs were compared by evaluating dialysis-related expenses. MAIN OUTCOME MEASURES: Quality-of-life parameters...

Radiological manifestations of biphosphonate treatment with APD in a child suffering from osteogenesis imperfecta

International Nuclear Information System (INIS)

Devogelaer, J.P.; Deuxchaisnes, C.N. de; Malghem, J.; Maldague, B.

1987-01-01

A 12-year-old female suffering fromosteogenesis imperfecta (OI) was treated with 3-amino-1-hydroxypropylidene-1,1-bisphosphonate (APD) orally, 250 mg daily, for periods of 2 months, alternating with periods of 2 months of abstinence. Total duration of therapy was 1 year. Radiological and clinical improvement was striking. Furthermore, X-rays of the bones showed large, parallel radio-opaque striae, corresponding exactly to the periods of therapy. These were present in all metaphyses. (orig.)

Development of a High Precision Axial 3-D PET for Brain Imaging

CERN Document Server

Bolle, E; Casella, C; Chesi, E; Clinthorne, N; Cochran, E; De Leo, R; Dissertori, G; Djambazov, L; Honscheid, K; Huh, S; Johnson, I; Joram, C; Kagan, H; Lacasta, C; Lustermann, W; Meddi, F; Nappi, E; Nessi-Tedaldi, F; Oliver, J F; Pauss, F; Rafecas, M; Renker, D; Rudge, A; Schinzel, D; Schneider, T; Séguinot, J; Smith, S; Solevi, P; Stapnes, S; Vilardi, I; Weilhammer, P

2009-01-01

We describe a PET device based on a novel method to extract the coordinates of the interaction point of the 511 keV γ rays from 100 mm long and thin LYSO (Lutetium Yttrium OxyorthoSilicate) scintillator bars, positioned axially in the tomograph. The coordinate along the hit crystal is measured by using a hodoscope of Wave Length Shifting (WLS) plastic strips mounted perpendicularly to each plane of scintillators. As photodetectors, new Geiger mode Avalanche PhotoDetectors (G-APDs) with integrated electronics are being used to detect both the hit crystal in a block (x and y coordinates) and the interaction point in the crystal (z coordinate) through the light escaping from the crystal and transmitted to the WLS strips. In this way, the γ interaction point can be determined with a spatial resolution of few cubic millimeters down to a minimum deposited energy of about 50 keV, resulting in a volumetric precision very close to the limits imposed by the physics of the positron annihilation. The method allows to i...

APD detectors for biological fluorescence spectroscopy

International Nuclear Information System (INIS)

Mazeres, S.; Borrel, V.; Magenc, C.; Courrech, J.L.; Bazer-Bachi, R.

2006-01-01

Fluorescence spectroscopy is a very convenient and widely used method for studying the molecular background of biological processes [L. Salome, J.L. Cazeil, A. Lopez, J.F. Tocanne, Eur. Biophys. J. 27 (1998) 391-402]. Chromophores are included in the structure under study and a flash of laser light induces fluorescence (Fluorescence Recovery After Photo-bleaching), the decay of which yields information on the polarity, the speed of rotation, and the speed of diffusion as well as on the temporal and spatial evolution of interactions between molecular species. The method can even be used to study living cells [J.F. Tocanne, L. Cezanne, A. Lopez, Prog. Lipid Res. 33 (1994) 203-237, L. Cezanne, A. Lopez, F. Loste, G. Parnaud, O. Saurel, P. Demange, J.F. Tocanne, Biochemistry 38 (1999) 2779-2786]. This is classically performed with a PM-based system. For biological reasons a decrease of the excitation of the cells is highly desirable. Because the fluorescence response then becomes fainter a significant improvement in detector capability would be welcome. We present here results obtained with an Avalanche Photo Diode (APD)-based system. The small sensitive area of detection allows a very significant improvement in signal/noise ratio, improvement in gain, and the opening-up of a new parameter space. With these new detectors we can begin the study of information transmission between cells through morphine receptors. This work involves both electronics engineers and biophysicists, so results and techniques in both fields will be presented here

Wavelength shifter strips and G-APD arrays for the read-out of the z-coordinate in axial PET modules

CERN Document Server

Braem, André; Joram, C; Rudge, A; Séguinot, Jacques; Weilhammer, P; De Leo, R; Nappi, E; Lustermann, W; Schinzel, D; Johnson, I; Renker, D; Albrecht, S

2008-01-01

The measurements presented in this paper are related to the development of a PET camera based on a 3-D axial geometry with excellent 3-D spatial, timing and energy resolution. The detector modules consist of matrices of long axially oriented scintillation crystal bars, which are individually coupled to photodetectors. The axial coordinate is derived from wavelength shifting (WLS) plastic strips orthogonally interleaved between the crystal bars and readout by G-APD arrays. We report on results from measurements with two LYSO crystal bars, read with PMTs, and two WLS strips readout with G-APD devices from Hamamatsu (called MPPC). The WLS strips are positioned orthogonally underneath the LYSO bars. Yields of about 80 photoelectrons from the WLS strips for an energy deposition in the LYSO crystals equivalent to the absorption of 511 keV photons are observed. The axial coordinate in the LYSO bars is reconstructed with a precision of about 1.9 mm (FWHM) using a digital reconstruction method. The resolution of an an...

Propagation velocity of an avalanche along the anode wire in a Geiger-Mueller counter filled with Q-gas at 1 ATM

International Nuclear Information System (INIS)

Matsuda, Kazunori; Sanada, Junpei

1990-01-01

Simple methods were applied to investigate the characteristics of a Geiger-Mueller counter with Q-gas flowing at 1 atm. The propagation velocity of the photon-aided avalanche along the anode wire depends linearly on the strength of the electric field in the counter. Its fluctuation (FWHM) as a function of distance between the source position and the end point is discussed. (orig.)

A high granularity plastic scintillator tile hadronic calorimeter with APD readout for a linear collider detector

Czech Academy of Sciences Publication Activity Database

Andreev, V.; Cvach, Jaroslav; Danilov, M.; Devitsin, E.; Dodonov, V.; Eigen, G.; Garutti, E.; Gilitzky, Yu.; Groll, M.; Heuer, R.D.; Janata, Milan; Kacl, Ivan; Korbel, V.; Kozlov, V. Yu; Meyer, H.; Morgunov, V.; Němeček, Stanislav; Pöschl, R.; Polák, Ivo; Raspereza, A.; Reiche, S.; Rusinov, V.; Sefkow, F.; Smirnov, P.; Terkulov, A.; Valkár, Š.; Weichert, Jan; Zálešák, Jaroslav

2006-01-01

Roč. 564, - (2006), s. 144-154 ISSN 0168-9002 R&D Projects: GA MŠk(CZ) LC527; GA MŠk(CZ) 1P05LA259; GA ČR(CZ) GA202/05/0653 Institutional research plan: CEZ:AV0Z10100502 Keywords : hadronic calorimeter * plastic scintillator tile * APD readout * linear collider detector Subject RIV: BF - Elementary Particles and High Energy Physics Impact factor: 1.185, year: 2006

Tests of gas sampling electromagnetic shower calorimeter

International Nuclear Information System (INIS)

Barbaro-Galtieri, A.; Carithers, W.; Day, C.; Johnson, K.J.; Wenzel, W.A.; Videau, H.

1983-01-01

An electromagnetic shower gas-sampling calorimeter has been tested in both Geiger and proportional discharge modes for incident electron energies in the range 0.125-16 GeV. The 0.2 radiation length-thick layers were lead-fiberglass laminates with cathode strips normal to the sense wires. The 5x10 mm 2 Geiger cells were formed with uniformly spaced nylon fibers perpendicular to the wires. Proportional mode measurements were carried out in the pressure range 1-10 atm. A Monte Carlo simulation is in good agreement with measured shower characteristics and has been used to predict the behavior for oblique of incidence and for various Geiger cell dimensions. (orig.)

Degradation and Its Control of Ultraviolet Avalanche Photodiodes Using PEDOT:PSS/ZnSSe Organic-Inorganic Hybrid Structure

Science.gov (United States)

Abe, Tomoki; Uchida, Shigeto; Tanaka, Keita; Fujisawa, Takanobu; Kasada, Hirofumi; Ando, Koshi; Akaiwa, Kazuaki; Ichino, Kunio

2018-05-01

We investigated device degradation in PEDOT:PSS/ZnSSe organic-inorganic hybrid ultraviolet avalanche photodiodes (UV-APDs). ZnSSe/n-GaAs wafers were grown by molecular beam epitaxy, and PEDOT:PSS window layers were formed by inkjet technique. We observed rapid degradation with APD-mode stress (˜ 30 V) in the N2 (4 N) atmosphere, while we observed no marked change in forward bias current stress and photocurrent stress. In the case of a vacuum condition, we observed no detectable degradation in the dark avalanche current with APD-mode stress. Therefore, the degradation in the PEDOT:PSS/ZnSSe interface under the APD-mode stress was caused by the residual water vapor or oxygen in the N2 atmosphere and could be controlled by vacuum packaging.

Improvements to the power supply and control systems of Geiger-Mueller counter tubes

International Nuclear Information System (INIS)

Gavin, Gerard; Amberny, Philippe.

1977-01-01

This invention aims to provide a power supply and control system for Geiger-Mueller counter tubes requiring only one high voltage output, corresponding to the 'active' phase voltage. With this in view, the invention proposes, inter alia, a system comprising a high voltage source connected to the anode of the GM tube whose cathode is connected to a determination and counting circuit, featuring a cathode connected to the source via an electronic switch and to earth by a component for holding the potential difference at a given level and by another electronic switch, placed in series. The switches are controlled in turn so as alternately to bring the cathode to a first voltage, enabling the tube to function, and to a second voltage, causing the blocking of the tube, this second voltage being set by the component creating the voltage difference [fr

Improvements to the power supply and control systems of Geiger-Mueller counter tubes

Energy Technology Data Exchange (ETDEWEB)

Gavin, G; Amberny, P

1977-10-19

This invention aims to provide a power supply and control system for Geiger-Mueller counter tubes requiring only one high voltage output, corresponding to the 'active' phase voltage. With this in view, the invention proposes, inter alia, a system comprising a high voltage source connected to the anode of the GM tube whose cathode is connected to a determination and counting circuit, featuring a cathode connected to the source via an electronic switch and to earth by a component for holding the potential difference at a given level and by another electronic switch, placed in series. The switches are controlled in turn so as alternately to bring the cathode to a first voltage, enabling the tube to function, and to a second voltage, causing the blocking of the tube, this second voltage being set by the component creating the voltage difference.

Construction techniques and operation principles of Geiger-Mueller counters using external cathode (Mazetype)

International Nuclear Information System (INIS)

Sevegnani, F.X.

1988-01-01

The construction techniques for external cathode (Maze) and internal cathode Geiger-Muller counters are described, showing the operation principles and the used material nature. More than 200 counter types were evaluated analysing their characteristics. The influence of several types of guard-rings was studied, for optimizing counter operation conditions. Plateaus of the order of 700 V with slope of 0,3%/100 V for the net counting rate, and 1400 V with a slope of 0,8/100 V for total counts using total pressure of 10 cmHg, were obtained. A counter for β detection, using blown glass window in one of the edges of the cylinder was constructed. Counters of long life using materials such as, mica, adhesive glues, etc., were obtained. The results shown that the best counter operation occurs when it is empty in a vacuum of 10 -5 mmHg. (M.C.K.) [pt

An application of high vacuum technique: fabrication of Geiger - Mueller counters and measurements of fallout radioactivity in Rio de Janeiro, Brazil, between 1950 and 1960

International Nuclear Information System (INIS)

Gross, B.

1986-01-01

The initial development of vacuum technology, in Brazil, is described. Special attention is given to the fabrication of Geiger-Mueller counters in the period between 1950-1960, abd the results obtained by its use in measurements of radioactivity produced by hydrogen weapons explosions in the atmosphere. (M.C.K.) [pt

Compact and high-sensitivity 100-Gb/s (4 × 25 Gb/s) APD-ROSA with a LAN-WDM PLC demultiplexer.

Science.gov (United States)

Yoshimatsu, Toshihide; Nada, Masahiro; Oguma, Manabu; Yokoyama, Haruki; Ohno, Tetsuichiro; Doi, Yoshiyuki; Ogawa, Ikuo; Takahashi, Hiroshi; Yoshida, Eiji

2012-12-10

We demonstrate an integrated 100 GbE receiver optical sub-assembly (ROSA) that incorporates a monolithic four-channel avalanche photodiode (APD) array and a planer lightwave circuit (PLC) based LAN-WDM demultiplexer. A record minimum receiver sensitivity of -20 dBm and 50-km error-free SMF transmission without an optical amplifier have been achieved.

In-situ stabilization of the Geiger (C and M Oil) Superfund Site

International Nuclear Information System (INIS)

Andromalos, K.B.; Ameel, M.E.

1994-01-01

The Geiger (C and M Oil) Superfund Site is the first US Army Corps of Engineers managed soil remediation project which utilized the in-situ stabilization/solidification technique to remediate the soil. This project involved the remediation of approximately 23,000 cubic yards of contaminated soil. Contaminants of concern included chromium, lead, PCB'S, toluene, benzene, and other organic compounds. Clean-up criteria for the stabilized material was equal to the National Primary Drinking Water Regulations, when tested using the TCLP leachate extraction method. Chromium, lead, and toluene were the main contaminants of concern, with TCLP clean-up goals of 150, 15 and 1,000 parts per billion (ppb), respectively. This National Priorities List (NPL) site is located near Charleston, SC and was an abandoned old waste oil facility that utilized unlined shallow trenches for the storage of waste oil. This paper summarizes the initial testing programs and the final production work at the site. Extensive testing was performed throughout all phases of the project. This testing was performed for the purpose of mix optimization, quality assurance, and verification testing. Specific parameters tested included: TCLP testing of organics, metals and PCBs, permeability testing, and unconfirmed compression strength

An Ultraviolet Excess in the Superluminous Supernova Gaia16apd Reveals a Powerful Central Engine

Energy Technology Data Exchange (ETDEWEB)

Nicholl, M.; Berger, E.; Blanchard, P. K.; Milisavljevic, D.; Challis, P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, Massachusetts 02138 (United States); Margutti, R. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Metzger, B. D. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Chornock, R., E-mail: matt.nicholl@cfa.harvard.edu [Astrophysical Institute, Department of Physics and Astronomy, 251B Clippinger Lab, Ohio University, Athens, OH 45701 (United States)

2017-01-20

Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below ∼3000 Å. Yan et al. have recently presented HST UV spectra and attributed the UV flux to low iron-group abundance in the outer ejecta, and hence reduced line blanketing. Here, we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite a typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by ∼10–15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV continuum is a result of a more powerful central power source, rather than a lack of UV absorption relative to other SLSNe or an additional component from interaction with the surrounding medium. These findings strongly support the central-engine hypothesis for hydrogen-poor SLSNe. An explosion ejecting M {sub ej} = 4.8(0.2/ κ ) M {sub ⊙}, where κ is the opacity in cm{sup 2} g{sup −1}, and forming a magnetar with spin period P = 2 ms, and B = 2 × 10{sup 14} G (lower than other SLSNe with comparable rise times) can consistently explain the light curve evolution and high temperature at peak. The host metallicity, Z = 0.18 Z {sub ⊙}, is comparable to other SLSNe.

Poster - 01: LabPET II Pixelated APD-Based PET Scanner for High-Resolution Preclinical Imaging

Energy Technology Data Exchange (ETDEWEB)

Lecomte, Roger; Arpin, Louis; Beaudoin, Jean-François; Bergeron, Mélanie; Bouchard, Jonathan; Bouziri, Haithem; Cadorette, Jules; Gaudin, Émilie; Jürgensen, Nadia; Koua, Konin Calliste; Trépanier, Pierre-Yves Lauzier; Leroux, Jean-Daniel; Loignon-Houle, Francis; Njejimana, Larissa; Paillé, Maxime; Paulin, Caroline; Pepin, Catherine; Pratte, Jean-François; Samson, Arnaud; Thibaudeau, Christian [Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, Université de Sherbrooke, Université de Sherbrooke, 3IT, Université de Sherbrooke, Novalgo Inc., Université de Sherbrooke, Université de Sherbrooke, CIMS/CRCHUS, 3IT, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, Université de Sherbrooke, 3IT, Université de Sherbrooke (Canada); and others

2016-08-15

Purpose: LabPET II is a new generation APD-based PET scanner designed to achieve sub-mm spatial resolution using truly pixelated detectors and highly integrated parallel front-end processing electronics. Methods: The basic element uses a 4×8 array of 1.12×1.12 mm{sup 2} Lu{sub 1.9}Y{sub 0.1}SiO{sub 5}:Ce (LYSO) scintillator pixels with one-to-one coupling to a 4×8 pixelated monolithic APD array mounted on a ceramic carrier. Four detector arrays are mounted on a daughter board carrying two flip-chip, 64-channel, mixed-signal, application-specific integrated circuits (ASIC) on the backside interfacing to two detector arrays each. Fully parallel signal processing was implemented in silico by encoding time and energy information using a dual-threshold Time-over-Threshold (ToT) scheme. The self-contained 128-channel detector module was designed as a generic component for ultra-high resolution PET imaging of small to medium-size animals. Results: Energy and timing performance were optimized by carefully setting ToT thresholds to minimize the noise/slope ratio. ToT spectra clearly show resolved 511 keV photopeak and Compton edge with ToT resolution well below 10%. After correction for nonlinear ToT response, energy resolution is typically 24±2% FWHM. Coincidence time resolution between opposing 128-channel modules is below 4 ns FWHM. Initial imaging results demonstrate that 0.8 mm hot spots of a Derenzo phantom can be resolved. Conclusion: A new generation PET scanner featuring truly pixelated detectors was developed and shown to achieve a spatial resolution approaching the physical limit of PET. Future plans are to integrate a small-bore dedicated mouse version of the scanner within a PET/CT platform.

Performances of a HGCDTE APD Based Detector with Electric Cooling for 2-μm DIAL/IPDA Applications

Directory of Open Access Journals (Sweden)

Dumas A.

2016-01-01

Full Text Available In this work we report on design and testing of an HgCdTe Avalanche Photodiode (APD detector assembly for lidar applications in the Short Wavelength Infrared Region (SWIR : 1,5 - 2 μm. This detector consists in a set of diodes set in parallel -making a 200 μm large sensitive area- and connected to a custom high gain TransImpedance Amplifier (TIA. A commercial four stages Peltier cooler is used to reach an operating temperature of 185K. Crucial performances for lidar use are investigated : linearity, dynamic range, spatial homogeneity, noise and resistance to intense illumination.

Study of a pure CsI crystal readout by APD for Belle II end cap ECL upgrade

Energy Technology Data Exchange (ETDEWEB)

Jin, Y., E-mail: jin@hep.phys.s.u-tokyo.ac.jp [Department of Physics, the University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033 (Japan); Aihara, H. [Department of Physics, the University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033 (Japan); Borshchev, O.V. [Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Profsoyuznaya st. 70, Moscow 117393 (Russian Federation); Epifanov, D.A. [Department of Physics, the University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033 (Japan); Ponomarenko, S.A.; Surin, N.M. [Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Profsoyuznaya st. 70, Moscow 117393 (Russian Federation)

2016-07-11

A scintillation counter consisting of a pure CsI crystal and avalanche photodiodes (Hamamatsu APD S8664-55 and S8664-1010) has been studied for the upgrade of the end cap electromagnetic calorimeter of Belle II detector. An essential increase of the light output was achieved with wavelength shifters based on nanostructured organosilicon luminophores. - Highlights: • A scintillation counter consisting of a pure CsI crystal and avalanche photodiodes has been studied. • The equivalent noise charge and equivalent noise energy of the counter have been measured. • An essential increase of the light output was achieved with wavelength shifters.

A positron emission tomograph based on LSO-APD modules with a sampling ADC read-out system for a students' advanced laboratory course

International Nuclear Information System (INIS)

Schneider, Florian R.; Mann, Alexander B.; Technische Univ. Muenchen, Klinikum rechts der Isar; Konorov, Igor; Paul, Stephan; Delso, Gaspar; Ziegler, Sibylle I.

2012-01-01

A one-day laboratory course on positron emission tomography (PET) for the education of physics students and PhD students in medical physics has been set up. In the course, the physical background and the principles of a PET scanner are introduced. Course attendees set the system in operation, calibrate it using a 22 Na point source and reconstruct different source geometries filled with 18 F. The PET scanner features an individual channel read-out of 96 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to avalanche photodiodes (APD). The analog data of each APD are digitized by fast sampling analog to digital converters (SADC) and processed within field programmable gate arrays (FPGA) to extract amplitudes and time stamps. All SADCs are continuously sampling with a precise rate of 80 MHz, which is synchronous for the whole system. The data is transmitted via USB to a Linux PC, where further processing and the image reconstruction are performed. The course attendees get an insight into detector techniques, modern read-out electronics, data acquisition and PET image reconstruction. In addition, a short introduction to some common software applications used in particle and high energy physics is part of the course. (orig.)

High performance waveguide-coupled Ge-on-Si linear mode avalanche photodiodes.

Science.gov (United States)

Martinez, Nicholas J D; Derose, Christopher T; Brock, Reinhard W; Starbuck, Andrew L; Pomerene, Andrew T; Lentine, Anthony L; Trotter, Douglas C; Davids, Paul S

2016-08-22

We present experimental results for a selective epitaxially grown Ge-on-Si separate absorption and charge multiplication (SACM) integrated waveguide coupled avalanche photodiode (APD) compatible with our silicon photonics platform. Epitaxially grown Ge-on-Si waveguide-coupled linear mode avalanche photodiodes with varying lateral multiplication regions and different charge implant dimensions are fabricated and their illuminated device characteristics and high-speed performance is measured. We report a record gain-bandwidth product of 432 GHz for our highest performing waveguide-coupled avalanche photodiode operating at 1510nm. Bit error rate measurements show operation with BER-12, in the range from -18.3 dBm to -12 dBm received optical power into a 50 Ω load and open eye diagrams with 13 Gbps pseudo-random data at 1550 nm.

Assembly technology of 4-side buttable MPPC

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, K.; Sato, K.; Yamada, R., E-mail: ryuta-ya@ssd.hpk.co.jp; Hosokawa, N.; Nagano, T.; Hayatsu, K.; Shimohara, T.; Ohkuwa, Y.; Oguri, A.

2013-12-21

The multi-pixel photon counter (MPPC) is a solid-state photon counting device consisting of a Geiger-mode APD and a quenching resistor. Through-silicon via technology (TSV) allows for the production of a discrete array version of the MPPC, creating a detector with the advantages of a larger active area and less dead space in its overall packaging when compared to other package types commonly used to produce MPPCs. Eliminating the need for a wire-bonding pad allows individual MPPCs to be tiled with minimum dead-space between individual detectors to form a four-sided buttable array. Selecting MPPCs that behave and perform very similarly to each other, especially when an operating voltage is applied, minimizes variation in performance between each channel and enhances channel uniformity. The output of discrete arrays of MPPCs can be easily readout with ASICs (application specific integrated circuits) due to their excellent channel uniformity characteristics, with minimum adjustment required by the ASIC. -- Author-Highlights: • TSV-MPPC and assembly technology are developed. • TSV-MPPC array is tiled in 4-sided buttable and has large and dense active area. • The output pulse of MPPC may have sharp rising edge by virtue of TSV. • The uniformity of the array can be maximized by neat inspection technology.

SiPM based readout system for PbWO4 crystals

Science.gov (United States)

Berra, A.; Bolognini, D.; Bonfanti, S.; Bonvicini, V.; Lietti, D.; Penzo, A.; Prest, M.; Stoppani, L.; Vallazza, E.

2013-08-01

Silicon PhotoMultipliers (SiPMs) consist of a matrix of small passively quenched silicon avalanche photodiodes operated in limited Geiger-mode (GM-APDs) and read out in parallel from a common output node. Each pixel (with a typical size in the 20-100 μm range) gives the same current response when hit by a photon; the SiPM output signal is the sum of the signals of all the pixels, which depends on the light intensity. The main advantages of SiPMs with respect to photomultiplier tubes (PMTs) are essentially the small dimensions, the insensitivity to magnetic fields and a low bias voltage. This contribution presents the performance of a SiPM based readout system for crystal calorimeters developed in the framework of the FACTOR/TWICE collaboration. The SiPM used for the test is a new device produced by FBK-irst which consists in a matrix of four sensors embedded in the same silicon substrate, called QUAD. The SiPM has been coupled to a lead tungstate crystal, an early-prototype version of the crystals developed for the electromagnetic calorimeter of the CMS experiment. New tests are foreseen using a complete module consisting of nine crystals, each one readout by two QUADs.

SiPM based readout system for PbWO4 crystals

International Nuclear Information System (INIS)

Berra, A.; Bolognini, D.; Bonfanti, S.; Bonvicini, V.; Lietti, D.; Penzo, A.; Prest, M.; Stoppani, L.; Vallazza, E.

2013-01-01

Silicon PhotoMultipliers (SiPMs) consist of a matrix of small passively quenched silicon avalanche photodiodes operated in limited Geiger-mode (GM-APDs) and read out in parallel from a common output node. Each pixel (with a typical size in the 20–100 μm range) gives the same current response when hit by a photon; the SiPM output signal is the sum of the signals of all the pixels, which depends on the light intensity. The main advantages of SiPMs with respect to photomultiplier tubes (PMTs) are essentially the small dimensions, the insensitivity to magnetic fields and a low bias voltage. This contribution presents the performance of a SiPM based readout system for crystal calorimeters developed in the framework of the FACTOR/TWICE collaboration. The SiPM used for the test is a new device produced by FBK-irst which consists in a matrix of four sensors embedded in the same silicon substrate, called QUAD. The SiPM has been coupled to a lead tungstate crystal, an early-prototype version of the crystals developed for the electromagnetic calorimeter of the CMS experiment. New tests are foreseen using a complete module consisting of nine crystals, each one readout by two QUADs

SiPM based readout system for PbWO{sub 4} crystals

Energy Technology Data Exchange (ETDEWEB)

Berra, A., E-mail: alessandro.berra@gmail.com [Università degli Studi dell' Insubria e INFN sezione di Milano Bicocca, Via Valleggio, 11-22100 Como (Italy); Bolognini, D.; Bonfanti, S. [Università degli Studi dell' Insubria e INFN sezione di Milano Bicocca, Via Valleggio, 11-22100 Como (Italy); Bonvicini, V. [INFN sezione di Trieste (Italy); Lietti, D. [Università degli Studi dell' Insubria e INFN sezione di Milano Bicocca, Via Valleggio, 11-22100 Como (Italy); Penzo, A. [INFN sezione di Trieste (Italy); Prest, M.; Stoppani, L. [Università degli Studi dell' Insubria e INFN sezione di Milano Bicocca, Via Valleggio, 11-22100 Como (Italy); Vallazza, E. [INFN sezione di Trieste (Italy)

2013-08-01

Silicon PhotoMultipliers (SiPMs) consist of a matrix of small passively quenched silicon avalanche photodiodes operated in limited Geiger-mode (GM-APDs) and read out in parallel from a common output node. Each pixel (with a typical size in the 20–100 μm range) gives the same current response when hit by a photon; the SiPM output signal is the sum of the signals of all the pixels, which depends on the light intensity. The main advantages of SiPMs with respect to photomultiplier tubes (PMTs) are essentially the small dimensions, the insensitivity to magnetic fields and a low bias voltage. This contribution presents the performance of a SiPM based readout system for crystal calorimeters developed in the framework of the FACTOR/TWICE collaboration. The SiPM used for the test is a new device produced by FBK-irst which consists in a matrix of four sensors embedded in the same silicon substrate, called QUAD. The SiPM has been coupled to a lead tungstate crystal, an early-prototype version of the crystals developed for the electromagnetic calorimeter of the CMS experiment. New tests are foreseen using a complete module consisting of nine crystals, each one readout by two QUADs.

Simulation of Silicon Photomultiplier Signals

Science.gov (United States)

Seifert, Stefan; van Dam, Herman T.; Huizenga, Jan; Vinke, Ruud; Dendooven, Peter; Lohner, Herbert; Schaart, Dennis R.

2009-12-01

In a silicon photomultiplier (SiPM), also referred to as multi-pixel photon counter (MPPC), many Geiger-mode avalanche photodiodes (GM-APDs) are connected in parallel so as to combine the photon counting capabilities of each of these so-called microcells into a proportional light sensor. The discharge of a single microcell is relatively well understood and electronic models exist to simulate this process. In this paper we introduce an extended model that is able to simulate the simultaneous discharge of multiple cells. This model is used to predict the SiPM signal in response to fast light pulses as a function of the number of fired cells, taking into account the influence of the input impedance of the SiPM preamplifier. The model predicts that the electronic signal is not proportional to the number of fired cells if the preamplifier input impedance is not zero. This effect becomes more important for SiPMs with lower parasitic capacitance (which otherwise is a favorable property). The model is validated by comparing its predictions to experimental data obtained with two different SiPMs (Hamamatsu S10362-11-25u and Hamamatsu S10362-33-25c) illuminated with ps laser pulses. The experimental results are in good agreement with the model predictions.

Development of high performance readout ASICs for silicon photomultipliers (SiPMs)

International Nuclear Information System (INIS)

Shen, Wei

2012-01-01

Silicon Photomultipliers (SiPMs) are novel kind of solid state photon detectors with extremely high photon detection resolution. They are composed of hundreds or thousands of avalanche photon diode pixels connected in parallel. These avalanche photon diodes are operated in Geiger Mode. SiPMs have the same magnitude of multiplication gain compared to the conventional photomultipliers (PMTs). Moreover, they have a lot of advantages such as compactness, relatively low bias voltage and magnetic field immunity etc. Special readout electronics are required to preserve the high performance of the detector. KLauS and STiC are two CMOS ASIC chips designed in particular for SiPMs. KLauS is used for SiPM charge readout applications. Since SiPMs have a much larger detector capacitance compared to other solid state photon detectors such as PIN diodes and APDs, a few special techniques are used inside the chip to make sure a descent signal to noise ratio for pixel charge signal can be obtained. STiC is a chip dedicated to SiPM time-of-flight applications. High bandwidth and low jitter design schemes are mandatory for such applications where time jitter less than tens of picoseconds is required. Design schemes and error analysis as well as measurement results are presented in the thesis.

Characteristics and fabrication of Geiger-Mueller counters with thin walls made of treated magnesium - Note about the use of araldite; Caracteristiques et fabrication des compteurs Geiger-Muller a paroi mince en magnesium traite - Note sur l'utilisation de l'araldite

Energy Technology Data Exchange (ETDEWEB)

Charbonnel, A

1949-03-01

This report describes, first, the advantage of magnesium for the manufacturing of Geiger-Mueller counters: suitable for machining and polishing, but strong reactivity with the counter atmosphere in the case of magnesium-rich alloys. Thus, the inside wall of the counter (cylinder of 20 mm diameter and 6 cm length) requires a non-reactive protective coating with excellent sealing properties. The synthetic resin 'araldite' fulfills all these conditions. The second part of the report describes the different steps of the fabrication of magnesium wall counters: lathe work, machining down and chemical polishing of hulls, assembly, tight sealing, pumping, filling-up and control tests. The average service life of these counters is of about 4 months. A note about the use and properties (hardening, mechanical properties, resistance..) of araldite is given in appendix. (J.S.)

A positron emission tomograph based on LSO-APD modules with a sampling ADC read-out system for a students' advanced laboratory course

Energy Technology Data Exchange (ETDEWEB)

Schneider, Florian R.; Mann, Alexander B. [Technische Univ. Muenchen, Garching (Germany). Physik-Department E18; Technische Univ. Muenchen, Klinikum rechts der Isar (Germany). Nuklearmedizinische Klinik und Poliklinik; Konorov, Igor; Paul, Stephan [Technische Univ. Muenchen, Garching (Germany). Physik-Department E18; Delso, Gaspar; Ziegler, Sibylle I. [Technische Univ. Muenchen, Klinikum rechts der Isar (Germany). Nuklearmedizinische Klinik und Poliklinik

2012-07-01

A one-day laboratory course on positron emission tomography (PET) for the education of physics students and PhD students in medical physics has been set up. In the course, the physical background and the principles of a PET scanner are introduced. Course attendees set the system in operation, calibrate it using a {sup 22}Na point source and reconstruct different source geometries filled with {sup 18}F. The PET scanner features an individual channel read-out of 96 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to avalanche photodiodes (APD). The analog data of each APD are digitized by fast sampling analog to digital converters (SADC) and processed within field programmable gate arrays (FPGA) to extract amplitudes and time stamps. All SADCs are continuously sampling with a precise rate of 80 MHz, which is synchronous for the whole system. The data is transmitted via USB to a Linux PC, where further processing and the image reconstruction are performed. The course attendees get an insight into detector techniques, modern read-out electronics, data acquisition and PET image reconstruction. In addition, a short introduction to some common software applications used in particle and high energy physics is part of the course. (orig.)

A positron emission tomograph based on LSO-APD modules with a sampling ADC read-out system for a students' advanced laboratory course.

Science.gov (United States)

Schneider, Florian R; Mann, Alexander B; Konorov, Igor; Delso, Gaspar; Paul, Stephan; Ziegler, Sibylle I

2012-06-01

A one-day laboratory course on positron emission tomography (PET) for the education of physics students and PhD students in medical physics has been set up. In the course, the physical background and the principles of a PET scanner are introduced. Course attendees set the system in operation, calibrate it using a (22)Na point source and reconstruct different source geometries filled with (18)F. The PET scanner features an individual channel read-out of 96 lutetium oxyorthosilicate (LSO) scintillator crystals coupled to avalanche photodiodes (APD). The analog data of each APD are digitized by fast sampling analog to digital converters (SADC) and processed within field programmable gate arrays (FPGA) to extract amplitudes and time stamps. All SADCs are continuously sampling with a precise rate of 80MHz, which is synchronous for the whole system. The data is transmitted via USB to a Linux PC, where further processing and the image reconstruction are performed. The course attendees get an insight into detector techniques, modern read-out electronics, data acquisition and PET image reconstruction. In addition, a short introduction to some common software applications used in particle and high energy physics is part of the course. Copyright © 2011. Published by Elsevier GmbH.

Synthesis of ent-BE-43547A1 reveals a potent hypoxia-selective anticancer agent and uncovers the biosynthetic origin of the APD-CLD natural products

Science.gov (United States)

Villadsen, Nikolaj L.; Jacobsen, Kristian M.; Keiding, Ulrik B.; Weibel, Esben T.; Christiansen, Bjørn; Vosegaard, Thomas; Bjerring, Morten; Jensen, Frank; Johannsen, Mogens; Tørring, Thomas; Poulsen, Thomas B.

2017-03-01

Tumour hypoxia is speculated to be a key driver of therapeutic resistance and metastatic dissemination. Consequently, the discovery of new potent agents that selectively target the hypoxic cell population may reveal new and untapped antitumour mechanisms. Here we demonstrate that the BE-43547 subclass of the APD-CLD (amidopentadienoate-containing cyclolipodepsipeptides) natural products possesses highly hypoxia-selective growth-inhibitory activity against pancreatic cancer cells. To enable this discovery, we have developed the first synthesis of the BE-43547-macrocyclic scaffold in 16 steps (longest linear sequence), which also allowed access to the full panel of relative stereoisomers and ultimately to the assignment of stereochemical configuration. Discrepancies between the spectroscopic signatures of the synthetic compounds with that originally reported for the BE-43547 members stimulated us to re-isolate the natural product from a BE-43547-producing microorganism during which we elucidated the biosynthetic gene clusters for the BE-43547 family as well as for all other known APD-CLDs. Our studies underline the exciting possibilities for the further development of the anticancer activities of these natural products.

Mapping Weathering and Alteration Minerals in the Comstock and Geiger Grade Areas using Visible to Thermal Infrared Airborne Remote Sensing Data

Science.gov (United States)

Vaughan, Greg R.; Calvin, Wendy M.

2005-01-01

To support research into both precious metal exploration and environmental site characterization a combination of high spatial/spectral resolution airborne visible, near infrared, short wave infrared (VNIR/SWIR) and thermal infrared (TIR) image data were acquired to remotely map hydrothermal alteration minerals around the Geiger Grade and Comstock alteration regions, and map the mineral by-products of weathered mine dumps in Virginia City. Remote sensing data from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS), SpecTIR Corporation's airborne hyperspectral imager (HyperSpecTIR), the MODIS-ASTER airborne simulator (MASTER), and the Spatially Enhanced Broadband Array Spectrograph System (SEBASS) were acquired and processed into mineral maps based on the unique spectral signatures of image pixels. VNIR/SWIR and TIR field spectrometer data were collected for both calibration and validation of the remote data sets, and field sampling, laboratory spectral analyses and XRD analyses were made to corroborate the surface mineralogy identified by spectroscopy. The resulting mineral maps show the spatial distribution of several important alteration minerals around each study area including alunite, quartz, pyrophyllite, kaolinite, montmorillonite/muscovite, and chlorite. In the Comstock region the mineral maps show acid-sulfate alteration, widespread propylitic alteration and extensive faulting that offsets the acid-sulfate areas, in contrast to the larger, dominantly acid-sulfate alteration exposed along Geiger Grade. Also, different mineral zones within the intense acid-sulfate areas were mapped. In the Virginia City historic mining district the important weathering minerals mapped include hematite, goethite, jarosite and hydrous sulfate minerals (hexahydrite, alunogen and gypsum) located on mine dumps. Sulfate minerals indicate acidic water forming in the mine dump environment. While there is not an immediate threat to the community, there are clearly sources of

Using Deep Learning for Gamma Ray Source Detection at the First G-APD Cherenkov Telescope (FACT)

Science.gov (United States)

Bieker, Jacob

2018-06-01

Finding gamma-ray sources is of paramount importance for Imaging Air Cherenkov Telescopes (IACT). This study looks at using deep neural networks on data from the First G-APD Cherenkov Telescope (FACT) as a proof-of-concept of finding gamma-ray sources with deep learning for the upcoming Cherenkov Telescope Array (CTA). In this study, FACT’s individual photon level observation data from the last 5 years was used with convolutional neural networks to determine if one or more sources were present. The neural networks used various architectures to determine which architectures were most successful in finding sources. Neural networks offer a promising method for finding faint and extended gamma-ray sources for IACTs. With further improvement and modifications, they offer a compelling method for source detection for the next generation of IACTs.

Characteristics and fabrication of Geiger-Mueller counters with thin walls made of treated magnesium - Note about the use of araldite; Caracteristiques et fabrication des compteurs Geiger-Muller a paroi mince en magnesium traite - Note sur l'utilisation de l'araldite

Energy Technology Data Exchange (ETDEWEB)

Charbonnel, A

1949-03-01

This report describes, first, the advantage of magnesium for the manufacturing of Geiger-Mueller counters: suitable for machining and polishing, but strong reactivity with the counter atmosphere in the case of magnesium-rich alloys. Thus, the inside wall of the counter (cylinder of 20 mm diameter and 6 cm length) requires a non-reactive protective coating with excellent sealing properties. The synthetic resin 'araldite' fulfills all these conditions. The second part of the report describes the different steps of the fabrication of magnesium wall counters: lathe work, machining down and chemical polishing of hulls, assembly, tight sealing, pumping, filling-up and control tests. The average service life of these counters is of about 4 months. A note about the use and properties (hardening, mechanical properties, resistance..) of araldite is given in appendix. (J.S.)

Development of a measurement device, using a Geiger-Mueller type detector, for the determination of the activity in a 99mTc generator prototype

International Nuclear Information System (INIS)

Urquizo, Rafael; Gago, Javier; Mendoza, Pablo; Cruz-Saco, Cesar; Rojas, Jorge

2014-01-01

This article presents the implementation of a measurement system using a Geiger-Mueller detector (GM) in order to adapt it into a 99m Tc generator prototype. The response signal of the measurement system designed in terms of count rate is linearly proportional to the variation of the activity measured between 280 and 170 mCi of 99m Tc with a relative error of ± 2,8 %. However, further tests are needed to evaluate the correlation for an activity level lower than 20 mCi in order to obtain an adequate range of use. (authors).

Characteristics and fabrication of Geiger-Mueller counters with thin walls made of treated magnesium - Note about the use of araldite

International Nuclear Information System (INIS)

Charbonnel, A.

1949-03-01

This report describes, first, the advantage of magnesium for the manufacturing of Geiger-Mueller counters: suitable for machining and polishing, but strong reactivity with the counter atmosphere in the case of magnesium-rich alloys. Thus, the inside wall of the counter (cylinder of 20 mm diameter and 6 cm length) requires a non-reactive protective coating with excellent sealing properties. The synthetic resin 'araldite' fulfills all these conditions. The second part of the report describes the different steps of the fabrication of magnesium wall counters: lathe work, machining down and chemical polishing of hulls, assembly, tight sealing, pumping, filling-up and control tests. The average service life of these counters is of about 4 months. A note about the use and properties (hardening, mechanical properties, resistance..) of araldite is given in appendix. (J.S.)

SPADs in CMOS : When Physics Meets Engineering

NARCIS (Netherlands)

Charbon, E.

2011-01-01

Single-photon avalanche diodes (SPADs) are a class of photodiodes biased above breakdown; in this mode of operation, known as Geiger mode, the devices are capable of detecting one or more photons with high timing accuracy. SPADs are useful in a variety of applications where picosecond timing

Development of analog solid-state photo-detectors for Positron Emission Tomography

International Nuclear Information System (INIS)

Bisogni, Maria Giuseppina; Morrocchi, Matteo

2016-01-01

Solid-state photo-detectors are one of the main innovations of past century in the field of sensors. First produced in the early forties with the invention of the p–n junction in silicon and the study of its optical properties, photo-detectors received a major boost in the sixties when the p-i-n (PIN) photodiode was developed and successfully used in several applications. The development of devices with internal gain, avalanche photodiodes (APD) first and then Geiger-mode avalanche photodiodes, named single photon avalanche diode (SPAD), leads to a substantial improvement in sensitivity and allowed single photon detection. Later on, thousands of SPADs have been assembled in arrays of few millimeters squared (named SiPM, silicon photo-multiplier) with single photon resolution. The high internal gain of SiPMs, together with other features peculiar of the silicon technology like compactness, speed and compatibility with magnetic fields, promoted SiPMs as the principal photo-detector competitor of photomultipliers in many applications from radiation detection to medical imaging. This paper provides a review of the properties of analog solid-state photo-detectors. Particular emphasis is given to latest advances on Positron Emission Tomography instrumentation boosted by the adoption of the silicon photo-detectors as an alternative to photomultiplier tubes (PMTs). Special attention is dedicated to the SiPMs, which are playing a key role in the development of innovative scanners.

Development of analog solid-state photo-detectors for Positron Emission Tomography

Energy Technology Data Exchange (ETDEWEB)

Bisogni, Maria Giuseppina, E-mail: giuseppina.bisogni@pi.infn.it; Morrocchi, Matteo

2016-02-11

Solid-state photo-detectors are one of the main innovations of past century in the field of sensors. First produced in the early forties with the invention of the p–n junction in silicon and the study of its optical properties, photo-detectors received a major boost in the sixties when the p-i-n (PIN) photodiode was developed and successfully used in several applications. The development of devices with internal gain, avalanche photodiodes (APD) first and then Geiger-mode avalanche photodiodes, named single photon avalanche diode (SPAD), leads to a substantial improvement in sensitivity and allowed single photon detection. Later on, thousands of SPADs have been assembled in arrays of few millimeters squared (named SiPM, silicon photo-multiplier) with single photon resolution. The high internal gain of SiPMs, together with other features peculiar of the silicon technology like compactness, speed and compatibility with magnetic fields, promoted SiPMs as the principal photo-detector competitor of photomultipliers in many applications from radiation detection to medical imaging. This paper provides a review of the properties of analog solid-state photo-detectors. Particular emphasis is given to latest advances on Positron Emission Tomography instrumentation boosted by the adoption of the silicon photo-detectors as an alternative to photomultiplier tubes (PMTs). Special attention is dedicated to the SiPMs, which are playing a key role in the development of innovative scanners.

High bit rate germanium single photon detectors for 1310nm

Science.gov (United States)

Seamons, J. A.; Carroll, M. S.

2008-04-01

There is increasing interest in development of high speed, low noise and readily fieldable near infrared (NIR) single photon detectors. InGaAs/InP Avalanche photodiodes (APD) operated in Geiger mode (GM) are a leading choice for NIR due to their preeminence in optical networking. After-pulsing is, however, a primary challenge to operating InGaAs/InP single photon detectors at high frequencies1. After-pulsing is the effect of charge being released from traps that trigger false ("dark") counts. To overcome this problem, hold-off times between detection windows are used to allow the traps to discharge to suppress after-pulsing. The hold-off time represents, however, an upper limit on detection frequency that shows degradation beginning at frequencies of ~100 kHz in InGaAs/InP. Alternatively, germanium (Ge) single photon avalanche photodiodes (SPAD) have been reported to have more than an order of magnitude smaller charge trap densities than InGaAs/InP SPADs2, which allowed them to be successfully operated with passive quenching2 (i.e., no gated hold off times necessary), which is not possible with InGaAs/InP SPADs, indicating a much weaker dark count dependence on hold-off time consistent with fewer charge traps. Despite these encouraging results suggesting a possible higher operating frequency limit for Ge SPADs, little has been reported on Ge SPAD performance at high frequencies presumably because previous work with Ge SPADs has been discouraged by a strong demand to work at 1550 nm. NIR SPADs require cooling, which in the case of Ge SPADs dramatically reduces the quantum efficiency of the Ge at 1550 nm. Recently, however, advantages to working at 1310 nm have been suggested which combined with a need to increase quantum bit rates for quantum key distribution (QKD) motivates examination of Ge detectors performance at very high detection rates where InGaAs/InP does not perform as well. Presented in this paper are measurements of a commercially available Ge APD

Joint CARE-ELAN, CARE-HHH-APD, and EUROTEV-WP3 Workshop on Electron Cloud Clearing

CERN Document Server

Scandale, Walter; Schulte, D; Zimmermann, F; Electron Cloud Effects and Technological Consequences; ECL2

2007-01-01

This report contains the Proceedings of the joint CARE-HHH-APD, CARE-ELAN, and EUROTEV-WP3 Mini-Workshop on 'Electron Cloud Clearing - Electron Cloud and Technical Consequences', "ECL2", held at CERN in Geneva, Switzerland, 1-2 March 2007). The ECL2 workshop explored novel technological remedies against electron-cloud formation in an accelerator beam pipe. A primary motivation for the workshop was the expected harmful electron-cloud effects in the upgraded LHC injectors and in future linear colliders, as well as recent beam observations in operating facilities like ANKA, CESR, KEKB, RHIC, and SPS. The solutions discussed at ECL2 included enamel-based clearing electrodes, slotted vacuum chambers, NEG coating, and grooves. Several of the proposed cures were assessed in terms of their clearing efficiency and the associated beam impedance. The workshop also reviewed new simulation tools like the 3D electron-ion build-up 'Faktor', modeling assumptions, analytical calculations, beam experiments, and laboratory meas...

Linear Mode HgCdTe Avalanche Photodiodes for Photon Counting Applications

Science.gov (United States)

Sullivan, William, III; Beck, Jeffrey; Scritchfield, Richard; Skokan, Mark; Mitra, Pradip; Sun, Xiaoli; Abshire, James; Carpenter, Darren; Lane, Barry

2015-01-01

An overview of recent improvements in the understanding and maturity of linear mode photon counting with HgCdTe electron-initiated avalanche photodiodes is presented. The first HgCdTe LMPC 2x8 format array fabricated in 2011 with 64 micron pitch was a remarkable success in terms of demonstrating a high single photon signal to noise ratio of 13.7 with an excess noise factor of 1.3-1.4, a 7 ns minimum time between events, and a broad spectral response extending from 0.4 micron to 4.2 micron. The main limitations were a greater than 10x higher false event rate than expected of greater than 1 MHz, a 5-7x lower than expected APD gain, and a photon detection efficiency of only 50% when greater than 60% was expected. This paper discusses the reasons behind these limitations and the implementation of their mitigations with new results.

The Magnetar Model of the Superluminous Supernova GAIA16apd and the Explosion Jet Feedback Mechanism

Energy Technology Data Exchange (ETDEWEB)

Soker, Noam, E-mail: soker@physics.technion.ac.il [Department of Physics, Technion—Israel Institute of Technology, Haifa 32000 (Israel)

2017-04-10

Under the assumption that jets explode core collapse supernovae (CCSNe) in a negative jet feedback mechanism (JFM), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. Under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, I derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. This relation is ( E {sub NS-spin}/ E {sub exp}) ≈ E {sub exp}/10{sup 52} erg; It shows that within the frame of the JFM explosion model of CCSNe, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. The existence of magnetars, if confirmed, such as in the recent super-energetic supernova GAIA16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven CCSN mechanisms.

Analysis of surface dark current dependent upon surface passivation in APD based on GaAs

International Nuclear Information System (INIS)

Song, Hong Joo; Roh, Cheong Hyun; Lee, Jun Ho; Choi, Hong Goo; Hahn, Cheol-Koo; Kim, Dong Ho; Park, Jung Ho

2009-01-01

In this paper, we investigated the dependence of reverse dark current on two types of surface passivation, one of which is polyimide and the other is SiN x , for InAs quantum dots/GaAs separate absorption, charge, multiplication avalanche photodiode (SACM APD). From the experimental results, we found that dark current was dominated by surface current, and not bulk current. It was also noted that SiN x passivation has a surface current that is lower by three to nine times in magnitude than that in polyimide passivation in the whole range of bias. To analyze the difference in dark current due to the passivation types, we propose the theoretical current components. This shows that the dark current of both passivation types is mainly composed of generation–recombination (G–R) and tunneling components, originating from the surface. However, each component has a different magnitude for passivation types, which can be explained by carrier concentration and trap density. The dependence of dark current on temperature shows the different behaviors between passivation types and supports a theoretical description of current components

Performances of Dose Measurement of Commercial Electronic Dosimeters using Geiger Muller Tube and PIN Diode

Energy Technology Data Exchange (ETDEWEB)

Yoo, Hyunjun; Kim, Chankyu; Kim, Yewon; Kim, Giyoon; Cho, Gyuseong [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

2014-05-15

There are two categories in personal dosimeters, one is passive type dosimeter such as TLD (thermoluminescence dosimeter) and the other is active type dosimeter such as electronic dosimeter can show radiation dose immediately while TLD needs long time to readout its data by heating process. For improving the reliability of measuring dose for any energy of radiations, electronic dosimeter uses energy filter by metal packaging its detector using aluminum or copper, but measured dose of electronic dosimeter with energy filter cannot be completely compensated in wide radiation energy region. So, in this paper, we confirmed the accuracy of dose measurement of two types of commercial EPDs using Geiger Muller tube and PIN diode with CsI(Tl) scintillator in three different energy of radiation field. The experiment results for Cs-137 was almost similar with calculation value in the results of both electronic dosimeters, but, the other experiment values with Na-22 and Co-60 had higher error comparing with Cs-137. These results were caused by optimization of their energy filters. The optimization was depending on its thickness of energy filter. So, the electronic dosimeters have to optimizing the energy filter for increasing the accuracy of dose measurement or the electronic dosimeter using PIN diode with CsI(Tl) scintillator uses the multi-channel discriminator for using its energy information.

The Magnetar Model of the Superluminous Supernova GAIA16apd and the Explosion Jet Feedback Mechanism

International Nuclear Information System (INIS)

Soker, Noam

2017-01-01

Under the assumption that jets explode core collapse supernovae (CCSNe) in a negative jet feedback mechanism (JFM), this paper shows that rapidly rotating neutron stars are likely to be formed when the explosion is very energetic. Under the assumption that an accretion disk or an accretion belt around the just-formed neutron star launch jets and that the accreted gas spins-up the just-formed neutron star, I derive a crude relation between the energy that is stored in the spinning neutron star and the explosion energy. This relation is ( E _N_S_-_s_p_i_n/ E _e_x_p) ≈ E _e_x_p/10"5"2 erg; It shows that within the frame of the JFM explosion model of CCSNe, spinning neutron stars, such as magnetars, might have significant energy in super-energetic explosions. The existence of magnetars, if confirmed, such as in the recent super-energetic supernova GAIA16apd, further supports the call for a paradigm shift from neutrino-driven to jet-driven CCSN mechanisms.

Reduction of the duration of the natural dead time of a 4 {pi} gas ionization counter operating in geiger-muller; Reduction de la duree de l'etat d'insensibilite naturelle d'un compteur a ionisation gazeuse de geometrie 4 {pi} travaillant en regime de Geiger-Muller

Energy Technology Data Exchange (ETDEWEB)

Becker, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Departement d' Electronique Generale, Laboratoire de Mesure des Radioelements

1967-07-01

It Is only possible to benefit from the 100 per cent efficiency of a 4 {pi} gas-ionisation detector operating in the Geiger-Muller regime (an efficiency which always appears difficult to attain in other detectors) if, one is able: - on the one hand to reduce considerably - on the other hand to fix very precisely the length at the real dead time of the system operating in the above conditions. Taking into account both the phenomena characteristic of the discharge in the regime under consideration, phenomena whose properties are described, and the geometrical conditions depending on the operation over a solid angle of 4 {pi}, it is shown that with an exterior electronic system for cutting off the discharge for example in 30 nanoseconds, absolute 4 {pi} G.M. measurements would become competitive with those now carried out almost in proportional conditions. Measurement results on sources of 5 x 10{sup 3} emissions per second maximum obtained by the use of a system for which the interval between the passage of a particle and the moment when the device has been made insensitive is still 60 nanoseconds have made it possible to confirm these statements. (author) [French] De l'efficacite de 100 pour cent du detecteur a ionisation gazeuse travaillant en regime de Geiger-Muller en geometrie 4 {pi} (efficacite toujours difficile a atteindre par d'autres detecteurs semble-t-il) on ne peut cependant beneficier que si l'on est capable: - d'une part, de reduire considerablement - d'autre part, de fixer de maniere tres precise la duree d'insensibilite reelle du systeme travaillant dans les conditions ci-dessus. Tenant compte des phenomenes propres a la decharge, dans le regime en question, phenomenes dont on rappeUto quelques caracteristiques, et des conditions geometriques propres a une detection dans un angle solide de 4 {pi} on montre qu'avec un systeme electronique de coupure externe de la decharge qui arreterait cette derniere en 30 nanosecondes par exemple, des mesures

The impact of thermal loading on repository performance at Yucca Mountain

International Nuclear Information System (INIS)

Buscheck, T.A.; Nitao, J.J.

1992-01-01

In the unsaturated zone at Yucca Mountain, liquid flow along preferential fracture pathways is the only credible mechanism capable of bringing water to waste packages and transporting radionuclide to the water table. Three categories of features or mechanisms will mitigate the impact of flow along preferential fracture pathways: (1) discontinuity in fracture pathways, (2) liquid-phase dispersion in fracture networks, and (3) fracture-matrix interaction. For repository areal power densities (APDs) that are too low to result in significant boiling or rock dry-out effects, the primary mode of fracture-matrix interaction is matrix imbibition. For high APDs, boiling and enhanced matrix imbibition due to rock dry-out significantly add to the capacity of the unsaturated zone to retard fracture-dominated flow. With the use of V-TOUGH code, hydrothermal flow calculations are made for a range of APDs and spent fuel ages. For APD > 20 kW/acre, repository-heat-generated flow of vapor and liquid in fractures is found to dominate the ambient hydrological system. For high APDs, boiling conditions can persist for 10,000 yr or longer and rock-dry benefits for at least 100,000 yr

Estimating accidental coincidences for pixelated PET detectors and singles list-mode acquisition

International Nuclear Information System (INIS)

Rafecas, M.; Torres, I.; Spanoudaki, V.; McElroy, D.P.; Ziegler, S.I.

2007-01-01

We have studied the validity of random estimation techniques for various low energy thresholds (LETs) and single list-mode data sets in small animal PET. While a LET below 255 keV helps to increase the sensitivity, it also results in an increase of random coincidences and inter-crystal scatter (ICS). The study is carried out for MADPET-II, a dual-layer positron emission tomography (PET) scanner prototype consisting of LSO crystals read out individually by APDs. The data are acquired in singles list-mode format, and coincidences are computed post-acquisition. To estimate randoms, we have used the delayed coincidence window method (DW), and the singles rate model (SR). Various phantoms were simulated using GATE. For LETs under 255 keV, the number of random events R, estimated using the SR and the DW methods, is larger than the number of randoms which was directly computed from GATE simulations, and R(SR)>R(DW)>R(GATE). The higher the LET, the smaller the overestimation. For LETs >255 keV, R(DW)/R(GATE) ∼1. If scattered singles were excluded from the file, this discrepancy between R(DW or SR) and R(GATE) significantly diminished. This fact points out to ICS as the effect responsible for the mismatch, since for LETs lower than 255 keV, all singles related to an ICS event can be detected independently, thus altering the singles rate. Therefore, if low LETs are used, random estimation techniques should account for ICS

Non-Geiger-Mode Single-Photon Avalanche Detector with Low Excess Noise

Science.gov (United States)

Zhao, Kai; Lo, YuHwa; Farr, William

2010-01-01

This design constitutes a self-resetting (gain quenching), room-temperature operational semiconductor single-photon-sensitive detector that is sensitive to telecommunications optical wavelengths and is scalable to large areas (millimeter diameter) with high bandwidth and efficiencies. The device can detect single photons at a 1,550-nm wavelength at a gain of 1 x 10(exp 6). Unlike conventional single photon avalanche detectors (SPADs), where gain is an extremely sensitive function to the bias voltage, the multiplication gain of this device is stable at 1 x 10(exp 6) over a wide range of bias from 30.2 to 30.9 V. Here, the multiplication gain is defined as the total number of charge carriers contained in one output pulse that is triggered by the absorption of a single photon. The statistics of magnitude of output signals also shows that the device has a very narrow pulse height distribution, which demonstrates a greatly suppressed gain fluctuation. From the histograms of both pulse height and pulse charge, the equivalent gain variance (excess noise) is between 1.001 and 1.007 at a gain of 1 x 10(exp 6). With these advantages, the device holds promise to function as a PMT-like photon counter at a 1,550- nm wavelength. The epitaxial layer structure of the device allows photons to be absorbed in the InGaAs layer, generating electron/hole (e-h) pairs. Driven by an electrical field in InGaAs, electrons are collected at the anode while holes reach the multiplication region (InAlAs p-i-n structure) and trigger the avalanche process. As a result, a large number of e-h pairs are created, and the holes move toward the cathode. Holes created by the avalanche process gain large kinetic energy through the electric field, and are considered hot. These hot holes are cooled as they travel across a p -InAlAs low field region, and are eventually blocked by energy barriers formed by the InGaAsP/ InAlAs heterojunctions. The composition of the InGaAsP alloy was chosen to have an 80 meV valance band offset with InAlAs, which is high enough to hinder the transport of the already cooled holes. Being stopped by the energy barrier, holes are accumulated at the junctions to shield the electric field, resulting in a decrease of the electric field in the multiplication region. Because the impact ionization rate is extremely sensitive to the magnitude of the electric field, the field-screening effect drastically reduces the impact ionization rate and quenches the output signals. After the avalanche pulse signal is self-quenched, the accumulated holes at the InGaAsP/ InAlAs interface escape the energy barrier through thermal excitation and tunneling and finally leave the device. The device is thus reset and ready for subsequent photon detection. This recovery time is controlled by the height of the energy barrier and the hole-cooling rate.

Geiger-Mode Avalanche Photodiode Arrays Integrated to All-Digital CMOS Circuits

Science.gov (United States)

2016-01-20

important in photon‐starved applications, such as night vision or high‐temporal‐resolution imaging. Interest in such scenarios lead to Lincoln’s...information of interest. Lincoln Laboratory’s long-term vision is to merge these functions, so that the work of information extraction is carried...M. Boroson, David O. Caplan, Constantine J. Digenis, David R. Hearn, and Ryan C. Shoup, "Design of an Optical Photon Counting Array Receiver System

Real Time Coincidence Processing Algorithm for Geiger Mode LADAR using FPGAs

Science.gov (United States)

2017-01-09

current operating parameters and extrapo- lated for future system upgrades. Simulated ladar data is processed using the FPGA and compared to the Matlab ...high-level description of each processing step as well as implemented modules . This paper explores the implementation of a modified “base- line... Simulation Data. The data set ran through the original Matlab code as well as a Modelsim simulation and the output images were compared using Matlab’s

Azimuthal spectrum after parametric down-convertion with radial degrees of freedom

CSIR Research Space (South Africa)

Zhang, Y

2014-08-01

Full Text Available of the OAM spectrum, i.e. the spiral bandwidth.6–10 Hence, a large spiral bandwidth indicates that an OAM entangled quantum state contains more OAM degrees of freedom that can be used to encode quantum information. The Laguerre-Gaussian (LG) modes are OAM... counter (CC). 50/50 beam splitter Laser BBO A B SLM SLM SMF SMF CC APD APD Signal Idler Figure 1. Diagram of the experimental setup used to prepare and measure the OAM entangled photon pairs. 3.2 Modelling the experiment Due to the experimental parameters...

CARE-HHH-APD Workshop on Finalizing the Roadmap for the Upgrade of the CERN and GSI Accelerator Complex

CERN Document Server

Zimmermann, Frank; BEAM'07; BEAM 2007; Finalizing the Roadmap for the Upgrade of the LHC and GSI Accelerator Complex

2008-01-01

This report contains the Proceedings of the CARE-HHH-APD Event BEAM’07, “Finalizing the Roadmap for the Upgrade of the CERN & GSI Accelerator Complex,” which was held at CERN in Geneva, Switzerland, from 1 to 5 October 2007. BEAM’07 was primarily devoted to beam dynamics limitations for the two, or three, alternative baseline scenarios of the LHC luminosity upgrade and to critical design choices for the upgrade of the LHC injector complex at CERN and for the FAIR complex at GSI. It comprised five parts: (1) a Mini-Workshop on LHC+ Beam Performance, (2) a CERN-GSI Meeting on Collective Effects, (3) the Francesco Ruggiero Memorial Symposium, (4) a Mini-Workshop on the LHC Injectors Upgrade, and (5) the BEAM’07 Summaries. Topics addressed in the first mini-workshop of BEAM’07 ranged from the luminosity performance reach of the upgraded LHC in different scenarios, over the generation and stability of the future LHC beams, the turnaround time, beam–beam effects, luminosity levelling methods, and ...

CMOS integrated avalanche photodiodes and frequency-mixing optical sensor front end for portable NIR spectroscopy instruments.

Science.gov (United States)

Yun, Ruida; Sthalekar, Chirag; Joyner, Valencia M

2011-01-01

This paper presents the design and measurement results of two avalanche photodiode structures (APDs) and a novel frequency-mixing transimpedance amplifier (TIA), which are key building blocks towards a monolithically integrated optical sensor front end for near-infrared (NIR) spectroscopy applications. Two different APD structures are fabricated in an unmodified 0.18 \\im CMOS process, one with a shallow trench isolation (STI) guard ring and the other with a P-well guard ring. The APDs are characterized in linear mode. The STI bounded APD demonstrates better performance and exhibits 3.78 A/W responsivity at a wavelength of 690 nm and bias voltage of 10.55 V. The frequency-mixing TIA (FM-TIA) employs a T-feedback network incorporating gate-controlled transistors for resistance modulation, enabling the simultaneous down-conversion and amplification of the high frequency modulated photodiode (PD) current. The TIA achieves 92 dS Ω conversion gain with 0.5 V modulating voltage. The measured IIP(3) is 10.6/M. The amplifier together with the 50 Ω output buffer draws 23 mA from a1.8 V power supply.

Understanding the cellular mode of action of vernakalant using a computational model: answers and new questions

Directory of Open Access Journals (Sweden)

Loewe Axel

2015-09-01

Full Text Available Vernakalant is a new antiarrhythmic agent for the treatment of atrial fibrillation. While it has proven to be effective in a large share of patients in clinical studies, its underlying mode of action is not fully understood. In this work, we aim to link experimental data from the subcellular, tissue, and system level using an in-silico approach. A Hill’s equation-based drug model was extended to cover the frequency dependence of sodium channel block. Two model variants were investigated: M1 based on subcellular data and M2 based on tissue level data. 6 action potential (AP markers were evaluated regarding their dose, frequency and substrate dependence. M1 comprising potassium, sodium, and calcium channel block reproduced the reported prolongation of the refractory period. M2 not including the effects on potassium channels reproduced reported AP morphology changes on the other hand. The experimentally observed increase of ERP accompanied by a shortening of APD90 was not reproduced. Thus, explanations for the drug-induced changes are provided while none of the models can explain the effects in their entirety. These results foster the understanding of vernakalant’s cellular mode of action and point out relevant gaps in our current knowledge to be addressed in future in-silico and experimental research on this aspiring antiarrhythmic agent.

Implementation of human thermal comfort information in Köppen-Geiger climate classification—the example of China

Science.gov (United States)

Yang, Shi-Qi; Matzarakis, Andreas

2016-11-01

Köppen-Geiger climate classification (KGC) is accepted and applied worldwide. The climatic parameters utilised in KGC, however, cannot indicate human thermal comfort (HTC) conditions or air humidity (AH) conditions directly, because they are originally based on climatic effects on vegetation, instead of that on human body directly. In addition, HTC is driven by meteorological parameters together. Thus, the objective of this study is to preliminarily implement the HTC information and the AH information in KGC. Physiologically equivalent temperature (PET) has been chosen as the HTC index, and vapour pressure (VP) is for the quantification of AH conditions. In this preliminary study, 12 Chinese cities in total have been taken into account as the assumed representatives of 11 climate types. Basic meteorological data of each city with 3-h resolution in 2000-2012 has been analysed. RayMan model has been applied to calculate PET within the same time period. Each climate type has been described by frequencies of PET and frequencies of VP. For example, the Aw (Sanya) has the most frequent occurrence of thermally stressful conditions compared to other climate types: PET in 22 % points in time of the year was above 35 °C. The driest AH conditions existed in Dwc (Lhasa) and Dfb (Urumqi) with VP rarely above 18 hPa in the wettest month. Implementation of the HTC information and the additional AH information in each climate type of KGC can be helpful for the topics of human health, energy consumption, tourism, as well as urban planning.

Implementation of human thermal comfort information in Köppen-Geiger climate classification-the example of China.

Science.gov (United States)

Yang, Shi-Qi; Matzarakis, Andreas

2016-11-01

Köppen-Geiger climate classification (KGC) is accepted and applied worldwide. The climatic parameters utilised in KGC, however, cannot indicate human thermal comfort (HTC) conditions or air humidity (AH) conditions directly, because they are originally based on climatic effects on vegetation, instead of that on human body directly. In addition, HTC is driven by meteorological parameters together. Thus, the objective of this study is to preliminarily implement the HTC information and the AH information in KGC. Physiologically equivalent temperature (PET) has been chosen as the HTC index, and vapour pressure (VP) is for the quantification of AH conditions. In this preliminary study, 12 Chinese cities in total have been taken into account as the assumed representatives of 11 climate types. Basic meteorological data of each city with 3-h resolution in 2000-2012 has been analysed. RayMan model has been applied to calculate PET within the same time period. Each climate type has been described by frequencies of PET and frequencies of VP. For example, the Aw (Sanya) has the most frequent occurrence of thermally stressful conditions compared to other climate types: PET in 22 % points in time of the year was above 35 °C. The driest AH conditions existed in Dwc (Lhasa) and Dfb (Urumqi) with VP rarely above 18 hPa in the wettest month. Implementation of the HTC information and the additional AH information in each climate type of KGC can be helpful for the topics of human health, energy consumption, tourism, as well as urban planning.

Low energy γ- γ and e{sup −}- γ PAC measurements using APDs and the probe nuclei {sup 83}Rb({sup 83}Kr) and {sup 83m}Kr({sup 83}Kr)

Energy Technology Data Exchange (ETDEWEB)

Arenz, M., E-mail: arenz@hiskp.uni-bonn.de; Vianden, R., E-mail: vianden@hiskp.uni-bonn.de [Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik (Germany)

2016-12-15

In the field of Perturbed Angular Correlation (PAC) measurements Avalanche Photo Diodes (APD) are rarely used, despite their favourable properties for fast counting purposes at low energies. This work demonstrates their application in combination with a simple and cheap custom build voltage sensitive preamplifier module. Using the PAC nuclei {sup 83}Rb({sup 83}Kr) and {sup 83m}Kr({sup 83}Kr), the time resolution of the set-up is analysed and the feasibility of precise timing measurements is shown.

Reduction of the duration of the natural dead time of a 4 {pi} gas ionization counter operating in geiger-muller; Reduction de la duree de l'etat d'insensibilite naturelle d'un compteur a ionisation gazeuse de geometrie 4 {pi} travaillant en regime de Geiger-Muller

Energy Technology Data Exchange (ETDEWEB)

Becker, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires, Departement d' Electronique Generale, Laboratoire de Mesure des Radioelements

1967-07-01

It Is only possible to benefit from the 100 per cent efficiency of a 4 {pi} gas-ionisation detector operating in the Geiger-Muller regime (an efficiency which always appears difficult to attain in other detectors) if, one is able: - on the one hand to reduce considerably - on the other hand to fix very precisely the length at the real dead time of the system operating in the above conditions. Taking into account both the phenomena characteristic of the discharge in the regime under consideration, phenomena whose properties are described, and the geometrical conditions depending on the operation over a solid angle of 4 {pi}, it is shown that with an exterior electronic system for cutting off the discharge for example in 30 nanoseconds, absolute 4 {pi} G.M. measurements would become competitive with those now carried out almost in proportional conditions. Measurement results on sources of 5 x 10{sup 3} emissions per second maximum obtained by the use of a system for which the interval between the passage of a particle and the moment when the device has been made insensitive is still 60 nanoseconds have made it possible to confirm these statements. (author) [French] De l'efficacite de 100 pour cent du detecteur a ionisation gazeuse travaillant en regime de Geiger-Muller en geometrie 4 {pi} (efficacite toujours difficile a atteindre par d'autres detecteurs semble-t-il) on ne peut cependant beneficier que si l'on est capable: - d'une part, de reduire considerablement - d'autre part, de fixer de maniere tres precise la duree d'insensibilite reelle du systeme travaillant dans les conditions ci-dessus. Tenant compte des phenomenes propres a la decharge, dans le regime en question, phenomenes dont on rappeUto quelques caracteristiques, et des conditions geometriques propres a une detection dans un angle solide de 4 {pi} on montre qu'avec un systeme electronique de coupure externe de la decharge qui arreterait cette derniere en 30

Characterization of midwave infrared InSb avalanche photodiode

Energy Technology Data Exchange (ETDEWEB)

Abautret, J., E-mail: johan.abautret@ies.univ-montp2.fr; Evirgen, A. [Université Montpellier, IES, UMR 5214, F-34095 Montpellier (France); CNRS, IES, UMR 5214, F-34095 Montpellier (France); SOFRADIR, BP 21, 38113 Veurey-Voroize (France); Perez, J. P.; Christol, P. [Université Montpellier, IES, UMR 5214, F-34095 Montpellier (France); CNRS, IES, UMR 5214, F-34095 Montpellier (France); Rothman, J. [CEA-LETI, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Cordat, A. [SOFRADIR, BP 21, 38113 Veurey-Voroize (France)

2015-06-28

This paper focuses on the InSb material potential for the elaboration of Avalanche Photodiodes (APD) for high performance infrared imaging applications, both in passive or active mode. The first InSb electron-APD structure was grown by molecular beam epitaxy, processed and electrically characterized. The device performances are at the state of the art for the InSb epi-diode technology, with a dark current density J(−50 mV) = 32 nA/cm{sup 2} at 77 K. Then, a pure electron injection was performed, and an avalanche gain, increasing exponentially, was observed with a gain value near 3 at −4 V at 77 K. The Okuto–Crowell model was used to determine the electron ionization coefficient α(E) in InSb, and the InSb gain behavior is compared with the one of InAs and MCT APDs.

A Low-Level Geiger-Counter for Tritium; Compteur Geiger a faible mouvement propre pour le tritium; Schetchik Gejgera s nizkim urovnem dlya tritiya; Contador Geiger de baja actividad de fondo para tritio

Energy Technology Data Exchange (ETDEWEB)

Von Buttlar, H; Stahl, W [Technische Hochschule, Darmstadt (Germany)

1962-01-15

pour controler la stabilite a long terme du systeme. (author) [Spanish] Contador Geiger de baja actividad de fondo para tritio. Los autores construyeron un tubo contador cilindrico de 11 l que contiene una serie de conductores de anticoincidencia en torno a un contador central de 2,9 l de volumen efectivo. La seccion de anticoincidencia esta separada del contador central por una delgada hoja de Hostaphan aluminizada. En el trabajo figura una serie de detalles constructivos. El gas que llena el contador consiste en una mezcla de etileno a 30 mm, de argon a 40 mm y la muestra de hidrogeno hasta 700 mm. Un circuito de extincion externo, cuyo tiempo muerto es de 7 ms, elimina eficazmente todos los impulsos demorados. Con un blindaje de hierro de 30 cm, el indice de recuento del contador central con hidrogeno gaseoso inerte es de 350 impulsos/min cuando el circuito de anticoincidencia no funciona y de unos 3 impulsos/min en el caso contrario. Suponiendo que un valor de 1 impulso/min por encima de la actividad de fondo sea significativo, resulta posible medir razones T/H muy pequenas, hasta 10{sup -16}, sin necesidad de proceder a un enriquecimiento isotopico. Se siguen realizando experimentos para verificar la estabilidad a largo plazo del dispositivo. (author) [Russian] Byla skonstruirovan a tsilindricheskaya trubka s ob{sup e}mom v 11 litrov, kotoraya soderzhit ryad provodov antisovpadeniya, okhvatyvayushchikh tsentral'nuyu chast' schetchika emkost'yu v 2,9 litra. TSentral'naya chast' schetchika otdelena ot sektsii antisovpadeniya tonkoj alyuminirovannoj Gostafanovoj fol'goj. Privodyatsya podrobnye dannye konstruktsii. Gaz dlya napolneniya schetchika sostoit iz 30 torr ehtilena, 40 torr argona i do 700 torr obraztsa vodoroda. Vneshnyaya tsep' gasheniya s mertvym vremenem v 7 msek. uspeshno ustranyaet posleduyushchie impul'sy. V 30 cm zheleznom ehkrane skorost' otcheta tsentral'noj chasti schetchika s ''mertvym'' vodorodnym gazom sostavlyaet 350 otschetov v minutu bez

The Road to the Common PET/CT Detector

Science.gov (United States)

Nassalski, Antoni; Moszynski, Marek; Szczesniak, Tomasz; Wolski, Dariusz; Batsch, Tadeusz

2007-10-01

Growing interest in the development of dual modality positron emission/X-rays tomography (PET/CT) systems prompts researchers to face a new challenge: to acquire both the anatomical and functional information in the same measurement, simultaneously using the same detection system and electronics. The aim of this work was to study a detector consisting of LaBr3, LSO or LYSO pixel crystals coupled to an avalanche photodiode (APD). The measurements covered tests of the detectors in PET and CT modes, respectively. The measurements included the determination of light output, energy resolution, the non-proportionality of the light yield and the time resolution for 511 keV annihilation quanta; analysis also included characterizing the PET detector, and determining the dependence of counting rate versus mean current of the APD in the X-ray detection. In the present experiment, the use of counting and current modes in the CT detection increases the dynamic range of the measured dose of X-rays by a factor of 20, compared to the counting mode alone.

Impulse response measurement in the HgCdTe avalanche photodiode

Science.gov (United States)

Singh, Anand; Pal, Ravinder

2018-04-01

HgCdTe based mid-wave infrared focal plane arrays (MWIR FPAs) are being developed for high resolution imaging and range determination of distant camouflaged targets. Effect of bandgap grading on the response time in the n+/ν/p+ HgCdTe electron avalanche photodiode (e-APD) is evaluated using impulse response measurement. Gain normalized dark current density of 2 × 10-9 A/cm2 at low reverse bias for passive mode and 2 × 10-4 A/cm2 at -8 V for active mode is measured in the fabricated APD device, yielding high gain bandwidth product of 2.4 THZ at the maximum gain. Diffusion of carriers is minimized to achieve transit time limited impulse response by introducing composition grading in the HgCdTe epilayer. The noise equivalent photon performance less than one is achievable in the FPA that is suitable for active cum passive imaging applications.

Will novel oral formulations change the management of inflammatory bowel disease?

DEFF Research Database (Denmark)

Nielsen, Ole Haagen; Seidelin, Jakob Benedict; Ainsworth, Mark Andrew

2016-01-01

the current approaches with promising new oral drugs with distinct modes of action, including: the Janus kinase inhibitors (i.e., tofacitinib, filgotinib and peficitinib); the immunomodulatory drug (laquinimod); a small α4 antagonist (AJM300); agonists for sphingosine-phosphate receptors (i.e., ozanimod, APD...

Hole-Initiated-Avalanche, Linear-Mode, Single-Photon-Sensitive Avalanche Photodetector with Reduced Excess Noise and Low Dark Count Rate, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A radiation hard, single photon sensitive InGaAs avalanche photodiode (APD) receiver technology will be demonstrated useful for long range space based optical...

Application of An Avalanche Photodiode in Synchrotron-Based Ultra-fast X-Radiography

International Nuclear Information System (INIS)

Cheong, S.-K.; Liu Jinyuan; Wang Jin; Powell, Christopher F.

2004-01-01

A possibility of using avalanche photodiode has been investigated while operated in current or continuous wave mode to accommodate high-intensity synchrotron x-ray beams in an ultra-fast x-radiography. To achieve a time resolution of 1 μs or better in a time-resolved x-radiograhic experiment, the entire time-sequence of the APD response to the pulsed synchrotron x-ray beam is recorded with time resolution of 1-2 ns. We have characterized the APD detector in the continuous wave mode to reveal its linearity, signal to noise ratio, and the time response with various circuit configurations. We have demonstrated that signal-to-noise ratio better than 1000 can be achieved, which is limited only by Poisson statistics. These detectors, coupled with finely focused x-rays, have been used to study structure and dynamics of supersonic fuel sprays with 50 μm-spatial resolution and μs-temporal resolution in the region close to an injection nozzle

Acute alteration of cardiac ECG, action potential, I{sub Kr} and the human ether-a-go-go-related gene (hERG) K{sup +} channel by PCB 126 and PCB 77

Energy Technology Data Exchange (ETDEWEB)

Park, Mi-Hyeong; Park, Won Sun; Jo, Su-Hyun, E-mail: suhyunjo@kangwon.ac.kr

2012-07-01

Polychlorinated biphenyls (PCBs) have been known as serious persistent organic pollutants (POPs), causing developmental delays and motor dysfunction. We have investigated the effects of two PCB congeners, 3,3′,4,4′-tetrachlorobiphenyl (PCB 77) and 3,3′,4,4′,5-pentachlorobiphenyl (PCB 126) on ECG, action potential, and the rapidly activating delayed rectifier K{sup +} current (I{sub Kr}) of guinea pigs' hearts, and hERG K{sup +} current expressed in Xenopus oocytes. PCB 126 shortened the corrected QT interval (QTc) of ECG and decreased the action potential duration at 90% (APD{sub 90}), and 50% of repolarization (APD{sub 50}) (P < 0.05) without changing the action potential duration at 20% (APD{sub 20}). PCB 77 decreased APD{sub 20} (P < 0.05) without affecting QTc, APD{sub 90}, and APD{sub 50}. The PCB 126 increased the I{sub Kr} in guinea-pig ventricular myocytes held at 36 °C and hERG K{sup +} current amplitude at the end of the voltage steps in voltage-dependent mode (P < 0.05); however, PCB 77 did not change the hERG K{sup +} current amplitude. The PCB 77 increased the diastolic Ca{sup 2+} and decreased Ca{sup 2+} transient amplitude (P < 0.05), however PCB 126 did not change. The results suggest that PCB 126 shortened the QTc and decreased the APD{sub 90} possibly by increasing I{sub Kr}, while PCB 77 decreased the APD{sub 20} possibly by other modulation related with intracellular Ca{sup 2+}. The present data indicate that the environmental toxicants, PCBs, can acutely affect cardiac electrophysiology including ECG, action potential, intracellular Ca{sup 2+}, and channel activity, resulting in toxic effects on the cardiac function in view of the possible accumulation of the PCBs in human body. -- Highlights: ► PCBs are known as serious environmental pollutants and developmental disruptors. ► PCB 126 shortened QT interval of ECG and action potential duration. ► PCB 126 increased human ether-a-go-go-related K{sup +} current and I{sub Kr}. �

A prototype high-resolution animal positron tomograph with avalanche photodiode arrays and LSO crystals

International Nuclear Information System (INIS)

Ziegler, S.I.; Pichler, B.J.; Rafecas, M.; Schwaiger, M.

2001-01-01

To fully utilize positron emission tomography (PET) as a non-invasive tool for tissue characterization, dedicated instrumentation is being developed which is specially suited for imaging mice and rats. Semiconductor detectors, such as avalanche photodiodes (APDs), may offer an alternative to photomultiplier tubes for the readout of scintillation crystals. Since the scintillation characteristics of lutetium oxyorthosilicate (LSO) are well matched to APDs, the combination of LSO and APDs seems favourable, and the goal of this study was to build a positron tomograph with LSO-APD modules to prove the feasibility of such an approach. A prototype PET scanner based on APD readout of small, individual LSO crystals was developed for tracer studies in mice and rats. The tomograph consists of two sectors (86 mm distance), each comprising three LSO-APD modules, which can be rotated for the acquisition of complete projections. In each module, small LSO crystals (3.7 x 3.7 x 12 mm 3 ) are individually coupled to one channel within matrices containing 2 x 8 square APDs (2.6 x 2.6 mm 2 sensitive area per channel). The list-mode data are reconstructed with a penalized weighted least squares algorithm which includes the spatially dependent line spread function of the tomograph. Basic performance parameters were measured with phantoms and first experiments with rats and mice were conducted to introduce this methodology for biomedical imaging. The reconstructed field of view covers 68 mm, which is 80% of the total detector diameter. Image resolution was shown to be 2.4 mm within the whole reconstructed field of view. Using a lower energy threshold of 450 keV, the system sensitivity was 350 Hz/MBq for a line source in air in the centre of the field of view. In a water-filled cylinder of 4.6 cm diameter, the scatter fraction at the centre of the field of view was 16% (450 keV threshold). The count rate was linear up to 700 coincidence counts per second. In vivo studies of anaesthetized

In-beam test of a DIRC Cherenkov radiator with SiPM

International Nuclear Information System (INIS)

Kroeck, B.; Hayrapetyan, A.; Foehl, K.; Merle, O.; Dueren, M.; Roy, B.J.; Peters, K.

2009-01-01

One of the crucial points for any high energy physics experiment is to obtain a good pion/kaon separation i.e. particle identification (PID). For particles in minimum ionising range, the conventional methods of PID using energy loss and time of flight become insufficient. In such a situation, the measurement of velocity of particles using Cherenkov radiation is an effective tool for PID in combination with momentum information from a tracking detector. The PANDA experiment at FAIR/ GSI plans to use a novel technique for PID with detection of internally reflected Cherenkov (DIRC) light. DIRC uses, in contrast to the conventional gas Cherenkov detectors, a solid radiator and total internal reflection to guide Cherenkov photons onto a detection plane where it will be detected by advanced photon counters. A SiPM is a very new generation photon counter that has several advantages over conventional PMTs. Several prototype Cherenkov detectors with different readout systems are being developed for R and D studies. One such prototype detector with Geiger-APD readout has been built at Giessen and was tested in-beam at GSI. The present report provides details of the very first test measurement

The impact of thermal loading on repository performance at Yucca Mountain

International Nuclear Information System (INIS)

Buscheck, T.A.; Nitao, J.J.

1992-01-01

This paper reports that in the unsaturated zone at Yucca Mountain, liquid flow along preferential fracture pathways is the only credible mechanism capable of bringing water to waste packages and transporting radionuclides to the water table. Three categories of features or mechanisms will mitigate the impact of flow along preferential fracture pathways: discontinuity in fracture pathways, liquid-phase dispersion in fracture networks, and fracture-matrix interaction. For repository areal power densities (APDs) that are too low to result in significant boiling or rock dry-out effects, the primary mode of fracture-matrix interaction is matrix imbibition. For high APDs, boiling and enhanced matrix imbibition due to rock dry-out significantly add to the capacity of the unsaturated zone to retard fracture-dominated flow

Silicon Photo-Multiplier Radiation Hardness Tests with a White Neutron Beam

International Nuclear Information System (INIS)

Montanari, A.; Tosi, N.; Pietropaolo, A.; Andreotti, M.; Baldini, W.; Calabrese, R.; Cibinetto, G.; Luppi, E.; Cotta Ramusino, A.; Malaguti, R.; Santoro, V.; Tellarini, G.; Tomassetti, L.; De Donato, C.; Reali, E.

2013-06-01

We report radiation hardness tests performed, with a white neutron beam, at the Geel Electron Linear Accelerator in Belgium on silicon Photo-Multipliers. These are semiconductor photon detectors made of a square matrix of Geiger-Mode Avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to about 6.2 x 10 9 1-MeV-equivalent neutrons per cm 2 . (authors)

Real-time scene and signature generation for ladar and imaging sensors

Science.gov (United States)

Swierkowski, Leszek; Christie, Chad L.; Antanovskii, Leonid; Gouthas, Efthimios

2014-05-01

This paper describes development of two key functionalities within the VIRSuite scene simulation program, broadening its scene generation capabilities and increasing accuracy of thermal signatures. Firstly, a new LADAR scene generation module has been designed. It is capable of simulating range imagery for Geiger mode LADAR, in addition to the already existing functionality for linear mode systems. Furthermore, a new 3D heat diffusion solver has been developed within the VIRSuite signature prediction module. It is capable of calculating the temperature distribution in complex three-dimensional objects for enhanced dynamic prediction of thermal signatures. With these enhancements, VIRSuite is now a robust tool for conducting dynamic simulation for missiles with multi-mode seekers.

A theoretical study of cluster radioactivity in platinum isotopes

Energy Technology Data Exchange (ETDEWEB)

Joseph, Deepthy Maria; Ashok, Nithu; Joseph, Antony [University of Calicut, Department of Physics, Malappuram, Kerala (India)

2018-01-15

The probable cluster decay modes in platinum isotopes are predicted with the help of effective liquid drop model. The calculated half-lives are compared with those of universal decay law model and with the experimental data. The investigation affirms the decisive role of neutron magicity in the phenomenon of cluster radioactivity. It is found that the probability of cluster emission decreases with the increase in the neutron number of parent nucleus. Geiger-Nuttall plots of the probable decay modes show linear behaviour, which in turn leads to the equation for logarithmic half-life for the clusters emitted from Pt isotopes. (orig.)

Determination of some fundamental characteristics of Geiger-Mueller counters. Applications to the study of delayed particles from cosmic-ray shower; Sur la determination de quelques caracteristiques fondamentales de compteurs de geiger-muller applications a l'etude des particules retardees des gerbes atmospheriques du rayonnement cosmique

Energy Technology Data Exchange (ETDEWEB)

Picard, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1954-06-15

After some historic recalls, the different phases of discharge of a Geiger-Mueller counter is studied. It measures, by oscillograph method, the time between the flow of a particle through a determined area of the counter and the response of the associated amplifier. This time length is composed by the latency period and the delay itself which depends on the amplifier sensitivity. The selection of particles which generate a discharge in the studied counter is obtained with a two coincidence counters telescope in which the aperture is limited by four counters in anticoincidence with the first two counters. The measures have been done with different distance values and an overvoltage V{sub s} which was applied to the counter. The dead time of a GM counter is also measured with a delayed coincidences method. The counter pulses which supply the coincidence circuit are delivered directly or with a known and variable delay. This method allows also to study the spurious pulses which are due to the positive ions impact on the counter cathode. Results for counters working in different conditions are given. It describes the system to limit the discharge which induces the increase of the life working of a counter, the decrease of its dead time and the reduction of the number of spurious pulses. In a second part, it describes the system to study the time correlation between different particles of the cosmic ray. An experiment concerning the presence of delayed particles in cosmic showers has permitted to specify the superior limit of this phenomena which is directly connected to the presence of heavy nuclear particles in the cosmic shower. (M.P.)

Geneva University - Silicon photomultiplier : features and applications

CERN Multimedia

Université de Genève

2012-01-01

GENEVA UNIVERSITY École de physique Département de physique nucléaire et corspusculaire 24, quai Ernest-Ansermet 1211 Genève 4 Tél.: (022) 379 62 73 Fax: (022) 379 69 92   Wednesday 7 March 2012 SEMINAIRE DE PHYSIQUE CORPUSCULAIRE 11.15 a.m. - Science II, Auditoire 1S081, 30, quai Ernest-Ansermet, 1211 Genève 4 SILICON PHOTOMULTIPLIER : FEATURES AND APPLICATIONS Dr Giulio SARACINO   University of Naples, Federico II   Silicon photomultipliers were developed about ten years ago and their use, unlike traditional photomultiplier tubes, is increasing more and more. They are an evolution of the avalanche photodiode working in Geiger mode regime. Hundreds of such diodes are connected in parallel, allowing single photon response, high detection efficiency, high gain at low bias voltage and very good timing performance. In spite of their Geiger regime, they can be considered linear devices, until the number of photon...

Two-mode PLC-based mode multi/demultiplexer for mode and wavelength division multiplexed transmission.

Science.gov (United States)

Hanzawa, Nobutomo; Saitoh, Kuimasa; Sakamoto, Taiji; Matsui, Takashi; Tsujikawa, Kyozo; Koshiba, Masanori; Yamamoto, Fumihiko

2013-11-04

We proposed a PLC-based mode multi/demultiplexer (MUX/DEMUX) with an asymmetric parallel waveguide for mode division multiplexed (MDM) transmission. The mode MUX/DEMUX including a mode conversion function with an asymmetric parallel waveguide can be realized by matching the effective indices of the LP(01) and LP(11) modes of two waveguides. We report the design of a mode MUX/DEMUX that can support C-band WDM-MDM transmission. The fabricated mode MUX/DEMUX realized a low insertion loss of less than 1.3 dB and high a mode extinction ratio that exceeded 15 dB. We used the fabricated mode MUX/DEMUX to achieve a successful 2 mode x 4 wavelength x 10 Gbps transmission over a 9 km two-mode fiber with a penalty of less than 1 dB.

Upgrade of the CMS hardron calorimeter for an upgraded LHC

OpenAIRE

Anderson, Jake

2012-01-01

The CMS barrel and endcap hadron calorimeters (Hcal) upgrading the current photo-sensors are hybrid photodiodes (HPDs) to meet the demands of the upgraded luminosity of the LHC. A key aspect of the Hcal upgrade is to add longitudinal segmentation to improve background rejection, energy resolution, and electron isolation at L1 trigger. The increased segmentation can be achieved by replacing the HPD's with multi-pixel Geiger-mode avalanche photodiodes. The upgraded electron...

Generalized social anxiety disorder and avoidant personality disorder: structural analysis and treatment outcome.

Science.gov (United States)

Huppert, Jonathan D; Strunk, Daniel R; Ledley, Deborah Roth; Davidson, Jonathan R T; Foa, Edna B

2008-01-01

There has been considerable controversy about whether generalized social phobia (GSP) and avoidant personality disorder (APD) are redundant diagnostic categories. In light of the ongoing controversy, more data are needed to help determine whether GSP and APD are independent constructs. Data were obtained from 335 people seeking treatment for GSP at a two site clinical trial. Indicators of GSP and APD were obtained along with assessments of demographic factors, level of functioning, and indicators of related psychopathology. Confirmatory factor analyses of indicators of GSP and APD suggested a somewhat better fit for a two-factor solution. Comparisons of GSP patients with and without APD suggested that in addition to having more severe social phobia symptoms, patients with APD were more depressed on a self-report measure and had more functional impairment, thereby suggesting potential utility of the diagnostic category of APD. Furthermore, the presence of APD predicted treatment response, in that patients with APD had more change early in treatment than those without APD. APD and GSP remain highly related constructs, and different aspects of these data support and dispute the utility of the diagnosis of APD in GSP. Possible new directions in conceptualizing APD are discussed. Published 2007 Wiley-Liss, Inc.

Molecular Mechanisms of Antipsychotic Drug-Induced Diabetes

Directory of Open Access Journals (Sweden)

Jiezhong Chen

2017-11-01

Full Text Available Antipsychotic drugs (APDs are widely prescribed to control various mental disorders. As mental disorders are chronic diseases, these drugs are often used over a life-time. However, APDs can cause serious glucometabolic side-effects including type 2 diabetes and hyperglycaemic emergency, leading to medication non-compliance. At present, there is no effective approach to overcome these side-effects. Understanding the mechanisms for APD-induced diabetes should be helpful in prevention and treatment of these side-effects of APDs and thus improve the clinical outcomes of APDs. In this review, the potential mechanisms for APD-induced diabetes are summarized so that novel approaches can be considered to relieve APD-induced diabetes. APD-induced diabetes could be mediated by multiple mechanisms: (1 APDs can inhibit the insulin signaling pathway in the target cells such as muscle cells, hepatocytes and adipocytes to cause insulin resistance; (2 APD-induced obesity can result in high levels of free fatty acids (FFA and inflammation, which can also cause insulin resistance. (3 APDs can cause direct damage to β-cells, leading to dysfunction and apoptosis of β-cells. A recent theory considers that both β-cell damage and insulin resistance are necessary factors for the development of diabetes. In high-fat diet-induced diabetes, the compensatory ability of β-cells is gradually damaged, while APDs cause direct β-cell damage, accounting for the severe form of APD-induced diabetes. Based on these mechanisms, effective prevention of APD-induced diabetes may need an integrated approach to combat various effects of APDs on multiple pathways.

Radiation dose rate meter

International Nuclear Information System (INIS)

Kronenberg, S.; Siebentritt, C.R.

1981-01-01

A combined dose rate meter and charger unit therefor which does not require the use of batteries but on the other hand produces a charging potential by means of a piezoelectric cylinder which is struck by a manually triggered hammer mechanism. A tubular type electrometer is mounted in a portable housing which additionally includes a geiger-muller (Gm) counter tube and electronic circuitry coupled to the electrometer for providing multi-mode operation. In one mode of operation, an rc circuit of predetermined time constant is connected to a storage capacitor which serves as a timed power source for the gm tube, providing a measurement in terms of dose rate which is indicated by the electrometer. In another mode, the electrometer indicates individual counts

PLC-based mode multi/demultiplexers for mode division multiplexing

Science.gov (United States)

Saitoh, Kunimasa; Hanzawa, Nobutomo; Sakamoto, Taiji; Fujisawa, Takeshi; Yamashita, Yoko; Matsui, Takashi; Tsujikawa, Kyozo; Nakajima, Kazuhide

2017-02-01

Recently developed PLC-based mode multi/demultiplexers (MUX/DEMUXs) for mode division multiplexing (MDM) transmission are reviewed. We firstly show the operation principle and basic characteristics of PLC-based MUX/DEMUXs with an asymmetric directional coupler (ADC). We then demonstrate the 3-mode (2LP-mode) multiplexing of the LP01, LP11a, and LP11b modes by using fabricated PLC-based mode MUX/DEMUX on one chip. In order to excite LP11b mode in the same plane, a PLC-based LP11 mode rotator is introduced. Finally, we show the PLC-based 6-mode (4LP-mode) MUX/DEMUX with a uniform height by using ADCs, LP11 mode rotators, and tapered waveguides. It is shown that the LP21a mode can be excited from the LP11b mode by using ADC, and the two nearly degenerated LP21b and LP02 modes can be (de)multiplexed separately by using tapered mode converter from E13 (E31) mode to LP21b (LP02) mode.

Single-Photon Avalanche Diodes (SPAD) in CMOS 0.35 µm technology

Energy Technology Data Exchange (ETDEWEB)

Pellion, D.; Jradi, K.; Brochard, N. [Le2i – CNRS/Univ. de Bourgogne, Dijon (France); Prêle, D. [APC – CNRS/Univ. Paris Diderot, Paris (France); Ginhac, D. [Le2i – CNRS/Univ. de Bourgogne, Dijon (France)

2015-07-01

Some decades ago single photon detection used to be the terrain of photomultiplier tube (PMT), thanks to its characteristics of sensitivity and speed. However, PMT has several disadvantages such as low quantum efficiency, overall dimensions, and cost, making them unsuitable for compact design of integrated systems. So, the past decade has seen a dramatic increase in interest in new integrated single-photon detectors called Single-Photon Avalanche Diodes (SPAD) or Geiger-mode APD. SPAD are working in avalanche mode above the breakdown level. When an incident photon is captured, a very fast avalanche is triggered, generating an easily detectable current pulse. This paper discusses SPAD detectors fabricated in a standard CMOS technology featuring both single-photon sensitivity, and excellent timing resolution, while guaranteeing a high integration. In this work, we investigate the design of SPAD detectors using the AMS 0.35 µm CMOS Opto technology. Indeed, such standard CMOS technology allows producing large surface (few mm{sup 2}) of single photon sensitive detectors. Moreover, SPAD in CMOS technologies could be associated to electronic readout such as active quenching, digital to analog converter, memories and any specific processing required to build efficient calorimeters (Silicon PhotoMultiplier – SiPM) or high resolution imagers (SPAD imager). The present work investigates SPAD geometry. MOS transistor has been used instead of resistor to adjust the quenching resistance and find optimum value. From this first set of results, a detailed study of the dark count rate (DCR) has been conducted. Our results show a dark count rate increase with the size of the photodiodes and the temperature (at T=22.5 °C, the DCR of a 10 µm-photodiode is 2020 count s{sup −1} while it is 270 count s{sup −1} at T=−40 °C for a overvoltage of 800 mV). A small pixel size is desirable, because the DCR per unit area decreases with the pixel size. We also found that the adjustment

Spatial-mode switchable ring fiber laser based on low mode-crosstalk all-fiber mode MUX/DEMUX

Science.gov (United States)

Ren, Fang; Yu, Jinyi; Wang, Jianping

2018-05-01

We report an all-fiber ring laser that emits linearly polarized (LP) modes based on the intracavity all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). Multiple LP modes in ring fiber laser are generated by taking advantage of mode MUX/DEMUX. The all-fiber mode MUX/DEMUX are composed of cascaded mode-selective couplers (MSCs). The output lasing mode of the ring fiber laser can be switched among the three lowest-order LP modes by employing combination of a mode MUX and a simple N × 1 optical switch. The slope efficiencies, optical spectra and mode profiles are measured.

Release of non-methane organic compounds during simulated landfilling of aerobically pretreated municipal solid waste.

Science.gov (United States)

Zhang, Yuanyuan; Yue, Dongbei; Liu, Jianguo; Lu, Peng; Wang, Ying; Liu, Jing; Nie, Yongfeng

2012-06-30

Characteristics of non-methane organic compounds (NMOCs) emissions during the anaerobic decomposition of untreated (APD-0) and four aerobically pretreated (APD-20, APD-39, APD-49, and APD-63) samples of municipal solid waste (MSW) were investigated in laboratory. The cumulative mass of the NMOCs of APD-20, APD-39, APD-49, and APD-63 accounted for 15%, 9%, 16%, and 15% of that of APD-0, respectively. The intensities of the NMOC emissions calculated by dividing the cumulative NMOC emissions by the quantities of organic matter removed (Q(VS)) decreased from 4.1 mg/kg Q(VS) for APD-0 to 0.8-3.4 mg/kg Q(VS) for aerobically pretreated MSW. The lipid and starch contents might have significant impact on the intensity of the NMOC emissions. Alkanes dominated the NMOCs released from the aerobically pretreated MSW, while oxygenated compounds were the chief component of the NMOCs generated from untreated MSW. Aerobic pretreatment of MSW prior to landfilling reduces the organic content of the waste and the intensity of the NMOC emissions, and increases the odor threshold, thereby reducing the environmental impact of landfills. Copyright © 2012 Elsevier Ltd. All rights reserved.

Personality functioning in patients with avoidant personality disorder and social phobia.

Science.gov (United States)

Eikenaes, Ingeborg; Hummelen, Benjamin; Abrahamsen, Gun; Andrea, Helene; Wilberg, Theresa

2013-12-01

Avoidant personality disorder (APD) and social phobia (SP) are closely related, such that they are suggested to represent different severity levels of one social anxiety disorder. This cross-sectional study aimed to compare patients with APD to patients with SP, with particular focus on personality dysfunction. Ninety-one adult patients were examined by diagnostic interviews and self-report measures, including the Index of Self-Esteem and the Severity Indices of Personality Problems. Patients were categorized in three groups; SP without APD (n = 20), APD without SP (n = 15), and APD with SP (n = 56). Compared to patients with SP without APD, patients with APD reported more symptom disorders, psychosocial problems, criteria of personality disorders, and personality dysfunction regarding self-esteem, identity and relational problems. These results indicate that APD involves more severe and broader areas of personality dysfunction than SP, supporting the conceptualization of APD as a personality disorder as proposed for DSM-5.

Stretch-dependent slow force response in isolated rabbit myocardium is Na+ dependent.

Science.gov (United States)

von Lewinski, Dirk; Stumme, Burkhard; Maier, Lars S; Luers, Claus; Bers, Donald M; Pieske, Burkert

2003-03-15

Stretch induces functional and trophic effects in mammalian myocardium via various signal transduction pathways. We tested stretch signal transduction on immediate and slow force response (SFR) in rabbit myocardium. Experiments were performed in isolated right ventricular muscles from adult rabbit hearts (37 degrees C, 1 Hz stimulation rate, bicarbonate-buffer). Muscles were rapidly stretched from 88% of optimal length (L88) to near optimal length (L98) for functional analysis. The resulting immediate and slow increases in twitch force (first phase and SFR, respectively) were assessed at reduced [Na+]o or without and with blockade of stretch activated ion channels (SACs), angiotensin-II (AT1) receptors, endothelin-A (ET(A)) receptors, Na+/H+-exchange (NHE1), reverse mode Na+/Ca2+-exchange (NCX), or Na+/K+-ATPase. The effects of stretch on sarcoplasmic reticulum Ca2+-load were characterized using rapid cooling contractures (RCCs). Intracellular pH was measured in BCECF-AM loaded muscles, and action potential duration (APD) was assessed using floating electrodes. On average, force increased to 216+/-8% of the pre-stretch value during the immediate phase, followed by a further increase to 273+/-10% during the SFR (n=81). RCCs significantly increased during SFR, whereas pH and APD did not change. Neither inhibition of SACs, AT1, or ET(A) receptors affected the stretch-dependent immediate phase nor SFR. In contrast, SFR was reduced by NHE inhibition and almost completely abolished by reduced [Na+]o or inhibition of reverse-mode NCX, whereas increased SFR was seen after raising [Na+]i by Na+/K+-ATPase inhibition. The data demonstrate the existence of a delayed, Na+- and Ca2+-dependent but pH and APD independent SFR to stretch in rabbit myocardium. This inotropic response appears to be independent of autocrine/paracrine AT1 or ET(A) receptor activation, but mediated through stretch-induced activation of NHE and reverse mode NCX.

Quantum random number generator based on quantum tunneling effect

OpenAIRE

Zhou, Haihan; Li, Junlin; Pan, Dong; Zhang, Weixing; Long, Guilu

2017-01-01

In this paper, we proposed an experimental implementation of quantum random number generator(QRNG) with inherent randomness of quantum tunneling effect of electrons. We exploited InGaAs/InP diodes, whose valance band and conduction band shared a quasi-constant energy barrier. We applied a bias voltage on the InGaAs/InP avalanche diode, which made the diode works under Geiger mode, and triggered the tunneling events with a periodic pulse. Finally, after data collection and post-processing, our...

The Relationship between Types of Attention and Auditory Processing Skills: Reconsidering Auditory Processing Disorder Diagnosis

Science.gov (United States)

Stavrinos, Georgios; Iliadou, Vassiliki-Maria; Edwards, Lindsey; Sirimanna, Tony; Bamiou, Doris-Eva

2018-01-01

Measures of attention have been found to correlate with specific auditory processing tests in samples of children suspected of Auditory Processing Disorder (APD), but these relationships have not been adequately investigated. Despite evidence linking auditory attention and deficits/symptoms of APD, measures of attention are not routinely used in APD diagnostic protocols. The aim of the study was to examine the relationship between auditory and visual attention tests and auditory processing tests in children with APD and to assess whether a proposed diagnostic protocol for APD, including measures of attention, could provide useful information for APD management. A pilot study including 27 children, aged 7–11 years, referred for APD assessment was conducted. The validated test of everyday attention for children, with visual and auditory attention tasks, the listening in spatialized noise sentences test, the children's communication checklist questionnaire and tests from a standard APD diagnostic test battery were administered. Pearson's partial correlation analysis examining the relationship between these tests and Cochrane's Q test analysis comparing proportions of diagnosis under each proposed battery were conducted. Divided auditory and divided auditory-visual attention strongly correlated with the dichotic digits test, r = 0.68, p attention battery identified as having Attention Deficits (ADs). The proposed APD battery excluding AD cases did not have a significantly different diagnosis proportion than the standard APD battery. Finally, the newly proposed diagnostic battery, identifying an inattentive subtype of APD, identified five children who would have otherwise been considered not having ADs. The findings show that a subgroup of children with APD demonstrates underlying sustained and divided attention deficits. Attention deficits in children with APD appear to be centred around the auditory modality but further examination of types of attention in both

Dual-cavity mode converter for a fundamental mode output in an over-moded relativistic backward-wave oscillator

Energy Technology Data Exchange (ETDEWEB)

Li, Jiawei; Huang, Wenhua [Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei 230027 (China); Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Xiao, Renzhen; Bai, Xianchen; Zhang, Yuchuan; Zhang, Xiaowei; Shao, Hao; Chen, Changhua [Science and Technology on High Power Microwave Laboratory, Northwest Institute of Nuclear Technology, Xi' an 710024 (China); Zhu, Qi [Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei 230027 (China)

2015-03-16

A dual-cavity TM{sub 02}–TM{sub 01} mode converter is designed for a dual-mode operation over-moded relativistic backward-wave oscillator. With the converter, the fundamental mode output is achieved. Particle-in-cell simulation shows that the efficiency of beam-wave conversion was over 46% and a pureTM{sub 01} mode output was obtained. Effects of end reflection provided by the mode converter were studied. Adequate TM{sub 01} mode feedback provided by the converter enhances conversion efficiency. The distance between the mode converter and extraction cavity critically affect the generation of microwaves depending on the reflection phase of TM{sub 01} mode feedback.

Dual-cavity mode converter for a fundamental mode output in an over-moded relativistic backward-wave oscillator

International Nuclear Information System (INIS)

Li, Jiawei; Huang, Wenhua; Xiao, Renzhen; Bai, Xianchen; Zhang, Yuchuan; Zhang, Xiaowei; Shao, Hao; Chen, Changhua; Zhu, Qi

2015-01-01

A dual-cavity TM 02 –TM 01 mode converter is designed for a dual-mode operation over-moded relativistic backward-wave oscillator. With the converter, the fundamental mode output is achieved. Particle-in-cell simulation shows that the efficiency of beam-wave conversion was over 46% and a pureTM 01 mode output was obtained. Effects of end reflection provided by the mode converter were studied. Adequate TM 01 mode feedback provided by the converter enhances conversion efficiency. The distance between the mode converter and extraction cavity critically affect the generation of microwaves depending on the reflection phase of TM 01 mode feedback

Single-mode fiber laser based on core-cladding mode conversion.

Science.gov (United States)

Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

2008-02-15

A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

Effect of modes interaction on the resistive wall mode stability

International Nuclear Information System (INIS)

Chen Longxi; Wu Bin

2013-01-01

Effects of modes interaction on the resistive wall mode (RWM) stability are studied. When considering the modes interaction effects, the linear growth rate of the most unstable (3, 1) mode decreases. After linear evolution, the RWM saturates at the nonlinear phase. The saturation can be attributed to flux piling up on the resistive wall. When some modes exist, the (3, 1) mode saturates at lower level compared with single mode evolution. Meanwhile, the magnetic energy of the (5, 2) mode increases correspondingly, but the magnetic energy saturation level of the (2, 1) mode changes weakly. (authors)

Scaling Fiber Lasers to Large Mode Area: An Investigation of Passive Mode-Locking Using a Multi-Mode Fiber.

Science.gov (United States)

Ding, Edwin; Lefrancois, Simon; Kutz, Jose Nathan; Wise, Frank W

2011-01-01

The mode-locking of dissipative soliton fiber lasers using large mode area fiber supporting multiple transverse modes is studied experimentally and theoretically. The averaged mode-locking dynamics in a multi-mode fiber are studied using a distributed model. The co-propagation of multiple transverse modes is governed by a system of coupled Ginzburg-Landau equations. Simulations show that stable and robust mode-locked pulses can be produced. However, the mode-locking can be destabilized by excessive higher-order mode content. Experiments using large core step-index fiber, photonic crystal fiber, and chirally-coupled core fiber show that mode-locking can be significantly disturbed in the presence of higher-order modes, resulting in lower maximum single-pulse energies. In practice, spatial mode content must be carefully controlled to achieve full pulse energy scaling. This paper demonstrates that mode-locking performance is very sensitive to the presence of multiple waveguide modes when compared to systems such as amplifiers and continuous-wave lasers.

Fast sub-electron detectors review for interferometry

Science.gov (United States)

Feautrier, Philippe; Gach, Jean-Luc; Bério, Philippe

2016-08-01

New disruptive technologies are now emerging for detectors dedicated to interferometry. The detectors needed for this kind of applications need antonymic characteristics: the detector noise must be very low, especially when the signal is dispersed but at the same time must also sample the fast temporal characteristics of the signal. This paper describes the new fast low noise technologies that have been recently developed for interferometry and adaptive optics. The first technology is the Avalanche PhotoDiode (APD) infrared arrays made of HgCdTe. In this paper are presented the two programs that have been developed in that field: the Selex Saphira 320x256 [1] and the 320x255 RAPID detectors developed by Sofradir/CEA LETI in France [2], [3], [4]. Status of these two programs and future developments are presented. Sub-electron noise can now be achieved in the infrared using this technology. The exceptional characteristics of HgCdTe APDs are due to a nearly exclusive impaction ionization of the electrons, and this is why these devices have been called "electrons avalanche photodiodes" or e-APDs. These characteristics have inspired a large effort in developing focal plan arrays using HgCdTe APDs for low photon number applications such as active imaging in gated mode (2D) and/or with direct time of flight detection (3D imaging) and, more recently, passive imaging for infrared wave front correction and fringe tracking in astronomical observations. In addition, a commercial camera solution called C-RED, based on Selex Saphira and commercialized by First Light Imaging [5], is presented here. Some groups are also working with instruments in the visible. In that case, another disruptive technology is showing outstanding performances: the Electron Multiplying CCDs (EMCCD) developed mainly by e2v technologies in UK. The OCAM2 camera, commercialized by First Light Imaging [5], uses the 240x240 EMMCD from e2v and is successfully implemented on the VEGA instrument on the CHARA

Triggered lightning return stroke luminosity to 1 km in two optical bands

Science.gov (United States)

Carvalho, F. L.; Uman, M. A.; Jordan, D. M.; Wilkes, R.; Kotovsky, D. A.; Hare, B.

2017-12-01

Measured luminosity waveforms are presented and analyzed as a function of time and channel height using two types of avalanche photodiodes (APDs) for 19 triggered-lightning return strokes during summer 2016. APD type I had an optical bandwidth from 200 nm to 1,000 nm, with peak response at 600 nm (green light), and APD type II had an optical bandwidth from 400 nm to 1,000 nm with a peak response at 800 nm (red light). Ten channel heights ranging from 0 to 1 km (in 100 m increments) were observed by both types of APDs, 20 total, and measured the luminosity in vertical channel slices of approximately 3 m. For APD type I, the return stroke luminosity waveforms generally decay faster following its singular initial peak (IP) than the waveforms recorded by APD type II. APD type II waveforms often exhibit a second maxima (SM) following the IP. Although the wave shapes recorded by each APD type diverge after the IP, the risetime of the initial luminosity wave front preceding the IP for both types of APDs agrees well. The divergence in the luminosity wave shapes following the IP indicates that APD type II is capable of recording spectral lines that are excited or enhanced after the IP more effectively than APD type I. In addition, the SM/IP ratio increases as a function of channel height, indicating that the spectral range better captured by APD type II is more predominant at the top of the channel than at the bottom. Finally, because APD type II responds better to longer wavelengths than APD type I, and because the SM occurs a few microseconds after the IP (at the channel-bottom), we conjecture that the SM following the IP is a consequence of spectral lines excited during the cooling of the channel, following the initial high-temperature/pressure stage. Our data suggests that the initial optical radiation during the return stroke is dominated by ionized atomic species (e.g. four NII lines between 450 and 600 nm, better captured by APD type I) radiated at higher

The impact of the UK aviation tax on carbon dioxide emissions and visitor numbers

NARCIS (Netherlands)

Mayor, K.; Tol, R.S.J.

2007-01-01

We use a model of domestic and international tourist numbers and flows to estimate the impact of the recent and proposed changes in the Air Passenger Duty (APD) of the United Kingdom. We look at four different scenarios (abolishing the APD, keeping the 2001 APD level, the 2007 APD and the

Transverse multibunch modes for non-rigid bunches, including mode coupling

Energy Technology Data Exchange (ETDEWEB)

Berg, J S; Ruth, R D [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

1996-08-01

A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold. (author)

Neutron diffraction study of the formation kinetics of ordered antiphase domains in titanium carbohydride TiCxHy

International Nuclear Information System (INIS)

Khidirov, I.

2015-01-01

The kinetics of formation and growth of ordered antiphase domains (APDs) in titanium carbohydride TiC 0.50 H 0.21 has been investigated by neutron diffraction. A model of ordered APDs is proposed. It is established that the pronounced ordering of interstitial atoms and APDs begin at 450°C. It is shown that the period of ordered APDs (P ≈ 10–12) is independent of the exposure time at a constant temperature. It is found that the temperature of ordered APDs, T OAPD , increases nonlinearly with an increase in the carbon concentration in the range 0.50 ≤ C/Ti ≤ 0.70. The formation temperature of ordered APDs is found to correlate with the concentration dependence of the order–disorder transition temperature and be 0.60 of the order–disorder transition temperature: T APD = 0.60Τ C

β1-Adrenoceptor autoantibodies affect action potential duration and delayed rectifier potassium currents in guinea pigs.

Science.gov (United States)

Zhao, Yuhui; Huang, Haixia; Du, Yunhui; Li, Xiao; Lv, Tingting; Zhang, Suli; Wei, Hua; Shang, Jianyu; Liu, Ping; Liu, Huirong

2015-01-01

β1-Adrenoceptor autoantibodies (β1-AAs) affect the action potential duration (APD) in cardiomyocytes and are related to ventricular arrhythmias. The delayed rectifier potassium current (I K) plays a crucial role in APD, but the effects of β1-AAs on I K have not been completely illuminated. This work aimed to observe the effects of β1-AAs on I K and APD and further explore the mechanisms of β1-AA-mediated ventricular arrhythmias. β1-AAs were obtained from sera of patients with coronary heart disease (CHD) and nonsustained ventricular tachycardia. With whole-cell patch clamp technique, action potentials and I K were recorded. The results illustrated 0.1 μmol/L β1-AAs shortened APD at 50 % (APD50) and 90 % (APD90) of the repolarization. However, at 0.01 μmol/L, β1-AAs had no effects on either APD90 or APD50 (P > 0.05). At 0.001 μmol/L, β1-AAs significantly prolonged APD90 and APD50. Moreover, β1-AAs (0.001, 0.01, 0.1 μmol/L) dose-dependently increased the rapidly activating delayed rectifier potassium current (I Kr), but similarly decreased the slowly activating delayed rectifier potassium current (I Ks) and increased L-type calcium currents at the different concentrations. Taken together, the IKr increase induced by high β1-AA concentrations is responsible for a significant APD reduction which would contribute to repolarization changes and trigger the malignant ventricular arrhythmias in CHD patients.

The recent development and study of silicon photomultiplier

International Nuclear Information System (INIS)

Saveliev, Valeri

2004-01-01

Recent developments and results from the study of a Silicon Solid State Photomultiplier (Si-PM) are presented. The basis of this new type of photodetector is a fine structure of microcells operating in the Geiger mode with an internal gain greater than 106. Common signal output allows for the detector to be operated in the proportional mode, and to reach a dynamic range of 1.5x103. Such photodetectors have shown single photon response at room temperature with a fast timing of ∼100ps. They are compact, robust and non-sensitive to magnetic fields. Results show the detection of low-intensity light in single photon mode and the detection of minimal ionizing particles using a scintillation tile for hadron calorimetry. The silicon photomultiplier is suitable for wide application in scintillation calorimetry, medical application, etc

H-mode physics

International Nuclear Information System (INIS)

Itoh, Sanae.

1991-06-01

After the discovery of the H-mode in ASDEX ( a tokamak in Germany ) the transition between the L-mode ( Low confinement mode ) and H-mode ( High confinement mode ) has been observed in many tokamaks in the world. The H-mode has made a breakthrough in improving the plasma parameters and has been recognized to be a universal phenomena. Since its discovery, the extensive studies both in experiments and in theory have been made. The research on H-mode has been casting new problems of an anomalous transport across the magnetic surface. This series of lectures will provide a brief review of experiments for explaining H-mode and a model theory of H-mode transition based on the electric field bifurcation. If the time is available, a new theoretical model of the temporal evolution of the H-mode will be given. (author)

Geiger Counter Technique

Science.gov (United States)

1942-01-01

ONLY; ADMINISTRATIVE/OPERATIONAL USE; 03 MAR 1999. OTHER REQUESTS SHALL BE REFERRED THROUGH COMMANDING OFFICER, NAVAL RESEARCH LAB , WASHINGTON, DC 20375...Used as Glow Tube Voltage + " -- -+a...... .-..... . .... . . . . . .. . . Plate 41. Tar of aCotrolust Voltaep with Gas Pressure lab A-gtarator of’ Plate...construation cf vapor comatera. Acst Lay metal wll menru as cathode aterial, but oxidiste copper Lad bras han given beest res-ts. fe ride choice of

Mode-to-mode energy transfers in convective patterns

Indian Academy of Sciences (India)

Abstract. We investigate the energy transfer between various Fourier modes in a low- dimensional model for thermal convection. We have used the formalism of mode-to-mode energy transfer rate in our calculation. The evolution equations derived using this scheme is the same as those derived using the hydrodynamical ...

Effects of mode coupling between low-mode radiation flux asymmetry and intermediate-mode ablator roughness on ignition capsule implosions

Directory of Open Access Journals (Sweden)

Jianfa Gu

2017-01-01

Full Text Available The low-mode shell asymmetry and high-mode hot spot mixing appear to be the main reasons for the performance degradation of the National Ignition Facility (NIF implosion experiments. The effects of the mode coupling between low-mode P2 radiation flux asymmetry and intermediate-mode L = 24 capsule roughness on the implosion performance of ignition capsule are investigated by two-dimensional radiation hydrodynamic simulations. It is shown that the amplitudes of new modes generated by the mode coupling are in good agreement with the second-order mode coupling equation during the acceleration phase. The later flow field not only shows large areal density P2 asymmetry in the main fuel, but also generates large-amplitude spikes and bubbles. In the deceleration phase, the increasing mode coupling generates more new modes, and the perturbation spectrum on the hot spot boundary is mainly from the strong mode interactions rather than the initial perturbation conditions. The combination of the low-mode and high-mode perturbations breaks up the capsule shell, resulting in a significant reduction of the hot spot temperature and implosion performance.

Emotional dysfunction in avoidant compared to borderline personality disorder: a study of affect consciousness.

Science.gov (United States)

Johansen, Merete Selsbakk; Normann-Eide, Eivind; Normann-Eide, Tone; Wilberg, Theresa

2013-12-01

Knowledge of emotional dysfunction in patients with avoidant personality disorder (APD) is much needed. The present study examined affect consciousness (AC) in patients with APD compared to borderline personality disorder (BPD). AC, defined as capacity to perceive, reflect on, tolerate, and express emotional experiences, is assumed to be central to structure-building in personality. The study tested the hypotheses that patients with APD have lower general AC and lower AC for pleasant affects compared to BPD. Fifty-nine patients, 26 with APD and 33 with BPD were rated on several aspects of AC using the specialized AC interview. The structured interview SCID-II was applied for diagnostic evaluations. The APD group had significantly lower levels of global AC and conceptual expressivity compared to the BPD group. Among 11 specific affects the APD group had significantly lower AC for interest and contempt. Emotional dysfunction is an important feature of APD and the findings indicate that psychotherapies for APD patients should focus on emotional experiences, aiming to improve emotional awareness, tolerance, and expressivity. The notion of a general avoidance of positive emotions in APD needs further exploration, including a possible dysfunction in the evolutionary based neuro-affective Seeking system. © 2013 The Scandinavian Psychological Associations.

Neutron diffraction study of the formation kinetics of ordered antiphase domains in titanium carbohydride TiC{sub x}H{sub y}

Energy Technology Data Exchange (ETDEWEB)

Khidirov, I., E-mail: khidirov@inp.uz [Uzbekistan Academy of Sciences, Institute of Nuclear Physics (Uzbekistan)

2015-09-15

The kinetics of formation and growth of ordered antiphase domains (APDs) in titanium carbohydride TiC{sub 0.50}H{sub 0.21} has been investigated by neutron diffraction. A model of ordered APDs is proposed. It is established that the pronounced ordering of interstitial atoms and APDs begin at 450°C. It is shown that the period of ordered APDs (P ≈ 10–12) is independent of the exposure time at a constant temperature. It is found that the temperature of ordered APDs, T{sub OAPD}, increases nonlinearly with an increase in the carbon concentration in the range 0.50 ≤ C/Ti ≤ 0.70. The formation temperature of ordered APDs is found to correlate with the concentration dependence of the order–disorder transition temperature and be 0.60 of the order–disorder transition temperature: T{sub APD} = 0.60Τ{sub C}.

PLC-based LP₁₁ mode rotator for mode-division multiplexing transmission.

Science.gov (United States)

Saitoh, Kunimasa; Uematsu, Takui; Hanzawa, Nobutomo; Ishizaka, Yuhei; Masumoto, Kohei; Sakamoto, Taiji; Matsui, Takashi; Tsujikawa, Kyozo; Yamamoto, Fumihiko

2014-08-11

A PLC-based LP11 mode rotator is proposed. The proposed mode rotator is composed of a waveguide with a trench that provides asymmetry of the waveguide. Numerical simulations show that converting LP11a (LP11b) mode to LP11b (LP11a) mode can be achieved with high conversion efficiency (more than 90%) and little polarization dependence over a wide wavelength range from 1450 nm to 1650 nm. In addition, we fabricate the proposed LP11 mode rotator using silica-based PLC. It is confirmed that the fabricated mode rotator can convert LP11a mode to LP11b mode over a wide wavelength range.

Sub-millisecond electron density profile measurement at the JET tokamak with the fast lithium beam emission spectroscopy system

Science.gov (United States)

Réfy, D. I.; Brix, M.; Gomes, R.; Tál, B.; Zoletnik, S.; Dunai, D.; Kocsis, G.; Kálvin, S.; Szabolics, T.; JET Contributors

2018-04-01

Diagnostic alkali atom (e.g., lithium) beams are routinely used to diagnose magnetically confined plasmas, namely, to measure the plasma electron density profile in the edge and the scrape off layer region. A light splitting optics system was installed into the observation system of the lithium beam emission spectroscopy diagnostic at the Joint European Torus (JET) tokamak, which allows simultaneous measurement of the beam light emission with a spectrometer and a fast avalanche photodiode (APD) camera. The spectrometer measurement allows density profile reconstruction with ˜10 ms time resolution, absolute position calculation from the Doppler shift, spectral background subtraction as well as relative intensity calibration of the channels for each discharge. The APD system is capable of measuring light intensities on the microsecond time scale. However ˜100 μs integration is needed to have an acceptable signal to noise ratio due to moderate light levels. Fast modulation of the beam up to 30 kHz is implemented which allows background subtraction on the 100 μs time scale. The measurement covers the 0.9 background subtraction, the relative calibration, and the comprehensive error calculation, runs a Bayesian density reconstruction code, and loads results to the JET database. The paper demonstrates the capability of the APD system by analyzing fast phenomena like pellet injection and edge localized modes.

Effects of multiple modes interaction on the resistive wall mode instability

International Nuclear Information System (INIS)

Chen, Longxi; Lei, Wenqing; Ma, Zhiwei; Wu, Bin

2013-01-01

The effects of multiple modes interaction on the resistive wall mode (RWM) are studied in a slab geometry with and without plasma flow. The modes interaction can have a large effect on both the linear growth rate and the nonlinear saturation level of the RWM. We found that modes interaction can suppress the linear growth rate for the most unstable mode. The plasma flow can also help to control the growth of the RWM. The RWM can be stabilized completely by a plasma flow when considering the modes interaction. The effect of modes interaction on the RWM is stronger for the mode rational surface in the vacuum than that in the plasma. The modes interaction results in a substantially lowered saturation level for the most unstable RWM. (paper)

Ballooning modes or Fourier modes in a toroidal plasma?

International Nuclear Information System (INIS)

Connor, J.W.; Taylor, J.B.

1987-01-01

The relationship between two different descriptions of eigenmodes in a torus is investigated. In one the eigenmodes are similar to Fourier modes in a cylinder and are highly localized near a particular rational surface. In the other they are the so-called ballooning modes that extend over many rational surfaces. Using a model that represents both drift waves and resistive interchanges the transition from one of these structures to the other is investigated. In this simplified model the transition depends on a single parameter which embodies the competition between toroidal coupling of Fourier modes (which enhances ballooning) and variation in frequency of Fourier modes from one rational surface to another (which diminishes ballooning). As the coupling is increased each Fourier mode acquires a sideband on an adjacent rational surface and these sidebands then expand across the radius to form the extended mode described by the conventional ballooning mode approximation. This analysis shows that the ballooning approximation is appropriate for drift waves in a tokamak but not for resistive interchanges in a pinch. In the latter the conventional ballooning effect is negligible but they may nevertheless show a ballooning feature. This is localized near the same rational surface as the primary Fourier mode and so does not lead to a radially extended structure

Single-Mode VCSELs

Science.gov (United States)

Larsson, Anders; Gustavsson, Johan S.

The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.

New systematics of cluster- and alpha-decay half lives

International Nuclear Information System (INIS)

Poenaru, D.N.; Greiner, W.

1994-01-01

Available as short communication only. The cluster (or 'exotic') radioactivities belong to a rich variety of nuclear decay modes which are phenomena intermediate between fission and alpha decay. In this contribution a single universal curve for the logarithm of the partial half-life for each kind of cluster radioactivity of even-even parent nuclei is presented. This handy relationship reproduces well the up to now 14 even-even half-life measurements within a ratio of 3.86 or rms=0.587 orders of magnitude. Its universality consists in the fact that instead of having different lines for various parent nuclei, like in the 'classical' systematics (Geiger-Nuttall plot) one can get practically only one line for each decay mode. (Author) 1 Fig., 2 Refs

A micropixel avalanche phototransistor for time of flight measurements

Energy Technology Data Exchange (ETDEWEB)

Sadigov, A., E-mail: saazik@yandex.ru [National Nuclear Research Center, Baku (Azerbaijan); Institute of Radiation Problems, Baku (Azerbaijan); Suleymanov, S. [National Nuclear Research Center, Baku (Azerbaijan); Institute of Radiation Problems, Baku (Azerbaijan); Ahmadov, F. [National Nuclear Research Center, Baku (Azerbaijan); Ahmadov, G. [National Nuclear Research Center, Baku (Azerbaijan); Joint Institute for Nuclear Research, Dubna (Russian Federation); Abdullayev, K. [National Aviation Academy, Baku (Azerbaijan); Akberov, R. [National Nuclear Research Center, Baku (Azerbaijan); Institute of Radiation Problems, Baku (Azerbaijan); Heydarov, N. [National Nuclear Research Center, Baku (Azerbaijan); Madatov, R. [Institute of Radiation Problems, Baku (Azerbaijan); Mukhtarov, R. [National Aviation Academy, Baku (Azerbaijan); Nazarov, M.; Valiyev, R. [National Nuclear Research Center, Baku (Azerbaijan)

2017-02-11

This paper presents results of studies of the silicon based new micropixel avalanche phototransistor (MAPT). MAPT is a modification of well-known silicon photomultipliers (SiPMs) and differs since each photosensitive pixel of the MAPT operates in Geiger mode and comprises an individual micro-transistor operating in binary mode. This provides a high amplitude single photoelectron signal with significantly shorter rise time. The obtained results are compared with appropriate parameters of known SiPMs. - Highlights: • A new photo detector – micropixel avalanche phototransistor was developed. • MAPT has a matrix of microtransistors with fast output. • In these modules the duration of the leading edge of the signal from the photodetectors are not worse than 50–100 ps.

Streaming tearing mode

Science.gov (United States)

Shigeta, M.; Sato, T.; Dasgupta, B.

1985-01-01

The magnetohydrodynamic stability of streaming tearing mode is investigated numerically. A bulk plasma flow parallel to the antiparallel magnetic field lines and localized in the neutral sheet excites a streaming tearing mode more strongly than the usual tearing mode, particularly for the wavelength of the order of the neutral sheet width (or smaller), which is stable for the usual tearing mode. Interestingly, examination of the eigenfunctions of the velocity perturbation and the magnetic field perturbation indicates that the streaming tearing mode carries more energy in terms of the kinetic energy rather than the magnetic energy. This suggests that the streaming tearing mode instability can be a more feasible mechanism of plasma acceleration than the usual tearing mode instability.

Competition and evolution of dielectric waveguide mode and plasmonic waveguide mode

Science.gov (United States)

Yuan, Sheng-Nan; Fang, Yun-Tuan

2017-10-01

In order to study the coupling and evolution law of the waveguide mode and two plasmonic surface modes, we construct a line defect waveguide based on hexagonal honeycomb plasmonic photonic crystal. Through adjusting the radius of the edge dielectric rods, the competition and evolution behaviors occur between dielectric waveguide mode and plasmonic waveguide mode. There are three status: only plasmonic waveguide modes occur for rA 0.25a; two kinds of modes coexist for 0.09a advantages in achieving slow light.

The Relationship between Aggression and Serum Thyroid Hormone Level in Individuals Diagnosed with Antisocial Personality Disorder.

Science.gov (United States)

Evrensel, Alper; Ünsalver, Barış Önen; Özşahin, Aytekin

2016-06-01

Aggression is one of the leading clinical characteristics of antisocial personality disorder (APD). Studies aiming to clarify and control the biological basis of aggression are ongoing. Thyroid hormones have been indicated to play a role in the development of aggression. The aim of this study was to examine the level of aggression and serum thyroid hormone in a sample of APD and to make contributions to this field with the current findings. The sample consisted of 96 subjects with a diagnosis of APD and 97 subjects as a control group. Structured Clinical Interview for DSM-IV Axis (SCID) 1 and 2 were used for the diagnosis, and the Buss-Perry Aggression Questionnaire was administered. Based on criminal patterns, the APD group was then divided into two subgroups: "criminal" and "noncriminal" APD groups. The day after the interview, after one night of fasting, blood was collected from the subjects between 7:00 a.m. and 9:00 a.m.. Thyroid function tests and other biochemical analyses related to the confounding variables were also administered. The study group and the control group were compared in terms of their aggression scores and thyroid hormone levels. The mean score of free T3 level in the criminal APD group was found to be significantly higher than that in the noncriminal APD group. APD subjects with higher free T3 levels also had higher aggression scores. In the noncriminal APD group, as serum free T3 and T4 levels increased, there was also an increment in the aggression scores. However, in the criminal APD group, there was no significant correlation between thyroid hormone levels and aggression. The findings of this study indicated that criminal and noncriminal APD groups actually show different properties.

Mode coupling in hybrid square-rectangular lasers for single mode operation

Energy Technology Data Exchange (ETDEWEB)

Ma, Xiu-Wen; Huang, Yong-Zhen, E-mail: yzhuang@semi.ac.cn; Yang, Yue-De; Xiao, Jin-Long; Weng, Hai-Zhong; Xiao, Zhi-Xiong [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100083 (China)

2016-08-15

Mode coupling between a square microcavity and a Fabry-Pérot (FP) cavity is proposed and demonstrated for realizing single mode lasers. The modulations of the mode Q factor as simulation results are observed and single mode operation is obtained with a side mode suppression ratio of 46 dB and a single mode fiber coupling loss of 3.2 dB for an AlGaInAs/InP hybrid laser as a 300-μm-length and 1.5-μm-wide FP cavity connected to a vertex of a 10-μm-side square microcavity. Furthermore, tunable single mode operation is demonstrated with a continuous wavelength tuning range over 10 nm. The simple hybrid structure may shed light on practical applications of whispering-gallery mode microcavities in large-scale photonic integrated circuits and optical communication and interconnection.

The role of the speech-language pathologist in identifying and treating children with auditory processing disorder.

Science.gov (United States)

Richard, Gail J

2011-07-01

A summary of issues regarding auditory processing disorder (APD) is presented, including some of the remaining questions and challenges raised by the articles included in the clinical forum. Evolution of APD as a diagnostic entity within audiology and speech-language pathology is reviewed. A summary of treatment efficacy results and issues is provided, as well as the continuing dilemma for speech-language pathologists (SLPs) charged with providing treatment for referred APD clients. The role of the SLP in diagnosing and treating APD remains under discussion, despite lack of efficacy data supporting auditory intervention and questions regarding the clinical relevance and validity of APD.

C-RED One and C-RED2: SWIR high-performance cameras using Saphira e-APD and Snake InGaAs detectors

Science.gov (United States)

Gach, Jean-Luc; Feautrier, Philippe; Stadler, Eric; Clop, Fabien; Lemarchand, Stephane; Carmignani, Thomas; Wanwanscappel, Yann; Boutolleau, David

2018-02-01

After the development of the OCAM2 EMCCD fast visible camera dedicated to advanced adaptive optics wavefront sensing, First Light Imaging moved to the SWIR fast cameras with the development of the C-RED One and the C-RED 2 cameras. First Light Imaging's C-RED One infrared camera is capable of capturing up to 3500 full frames per second with a subelectron readout noise and very low background. C-RED One is based on the last version of the SAPHIRA detector developed by Leonardo UK. This breakthrough has been made possible thanks to the use of an e-APD infrared focal plane array which is a real disruptive technology in imagery. C-RED One is an autonomous system with an integrated cooling system and a vacuum regeneration system. It operates its sensor with a wide variety of read out techniques and processes video on-board thanks to an FPGA. We will show its performances and expose its main features. In addition to this project, First Light Imaging developed an InGaAs 640x512 fast camera with unprecedented performances in terms of noise, dark and readout speed based on the SNAKE SWIR detector from Sofradir. The camera was called C-RED 2. The C-RED 2 characteristics and performances will be described. The C-RED One project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement N° 673944. The C-RED 2 development is supported by the "Investments for the future" program and the Provence Alpes Côte d'Azur Region, in the frame of the CPER.

A novel Silicon Photomultiplier with bulk integrated quench resistors: utilization in optical detection and tracking applications for particle physics

Energy Technology Data Exchange (ETDEWEB)

Petrovics, Stefan, E-mail: stp@hll.mpg.de [Halbleiterlabor der Max-Planck Gesellschaft, Otto-Hahn-Ring 6, D-81739 Munich (Germany); Andricek, Ladislav [Halbleiterlabor der Max-Planck Gesellschaft, Otto-Hahn-Ring 6, D-81739 Munich (Germany); Diehl, Inge; Hansen, Karsten [DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Jendrysik, Christian [Infineon Technologies AG, Am Campeon 1-12, D-85579 Neubiberg (Germany); Krueger, Katja [DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Lehmann, Raik; Ninkovic, Jelena [Halbleiterlabor der Max-Planck Gesellschaft, Otto-Hahn-Ring 6, D-81739 Munich (Germany); Reckleben, Christian [DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Richter, Rainer; Schaller, Gerhard; Schopper, Florian [Halbleiterlabor der Max-Planck Gesellschaft, Otto-Hahn-Ring 6, D-81739 Munich (Germany); Sefkow, Felix [DESY, Notkestrasse 85, D-22607 Hamburg (Germany)

2017-02-11

Silicon Photomultipliers (SiPMs) are a promising candidate for replacing conventional photomultiplier tubes (PMTs) in many applications, thanks to ongoing developments and advances in their technology. Conventional SiPMs are generally an array of avalanche photo diodes, operated in Geiger mode and read out in parallel, thus leading to the necessity of a high ohmic quenching resistor. This resistor enables passive quenching and is usually located on top of the array, limiting the fill factor of the device. In this paper, a novel detector concept with a bulk integrated quenching resistor will be recapped. In addition, due to other advantages of this novel detector design, a new concept, in which these devices will be utilized as tracking detectors for particle physics applications will be introduced, as well as first simulation studies and experimental measurements of this new approach. - Highlights: • A novel SiPM concept with bulk integrated quenching resistor is shown. • First prototypes of these SiPMs as tracking detectors are proposed. • Simulations of the Geiger efficiency suggest feasible operations at low overbias. • First measurements of the electron detection efficiency show promising results. • Measurements are in good agreement with the simulations.

Adaptive variational mode decomposition method for signal processing based on mode characteristic

Science.gov (United States)

Lian, Jijian; Liu, Zhuo; Wang, Haijun; Dong, Xiaofeng

2018-07-01

Variational mode decomposition is a completely non-recursive decomposition model, where all the modes are extracted concurrently. However, the model requires a preset mode number, which limits the adaptability of the method since a large deviation in the number of mode set will cause the discard or mixing of the mode. Hence, a method called Adaptive Variational Mode Decomposition (AVMD) was proposed to automatically determine the mode number based on the characteristic of intrinsic mode function. The method was used to analyze the simulation signals and the measured signals in the hydropower plant. Comparisons have also been conducted to evaluate the performance by using VMD, EMD and EWT. It is indicated that the proposed method has strong adaptability and is robust to noise. It can determine the mode number appropriately without modulation even when the signal frequencies are relatively close.

Peritoneal dialysis technique success during the initial 90 days of therapy.

Science.gov (United States)

Guest, Steven; Hayes, Andrew C; Story, Kenneth; Davis, Ira D

2012-01-01

Comparisons of technique success by peritoneal dialysis (PD) modality have typically excluded the initial 90 days of therapy. We analyzed a database of 51,469 new PD starts from 2004 to 2008 in the United States. The analysis concentrated on the initial 90 days of therapy to determine technique success and the impact of the continuous ambulatory PD (CAPD) and automated PD (APD) modalities. Overall, 13.3% of patients stopped PD within 90 days. Of patients starting directly on APD, 14.3% stopped PD within 90 days. Of patients starting on CAPD, 12.6% stopped PD within 90 days, and 63.4% changed to APD within 90 days. Only 3.3% of the latter patients failed to reach 90 days of therapy. By comparison, technique failure occurred in 28.8% of those initiating with and remaining on CAPD. We conclude that initial training to perform CAPD, with timely transfer to APD within the first 3 months, was associated with the greatest technique success at 90 days. The reasons for that success are unclear, and further research should be directed to determining factors responsible. It is possible that patients trained initially to CAPD but converted to APD have a greater understanding of the total therapy, which improves confidence. Those converted to APD may be more appreciative of the lifestyle benefits of APD, which translates into improved compliance; alternatively, technical factors associated with APD may be responsible. Those technical factors may include improved catheter function in the recumbent position during APD or the reduced infection risk associated with just 2 connect/disconnect procedures in APD compared with 8 in CAPD.

Avalanche photodiodes for ISABELLE detectors

International Nuclear Information System (INIS)

Strand, R.C.

1979-01-01

At ISABELLE some requirements for detecting bursts of photons are not met by standard photomultiplier tubes. The characteristics of immunity to magnetic fields, small size (few mm), low power consumption (approx. 100 mW), insensitivity to optical overloads, and wide dynamic range (approx. 60 dB) are achieved with difficulty, if at all, with PMTs. These are characteristics of the solid state avalanche photodiode (APD), the preferred detector for light-wave communications. Successful field tests with APD detectors stimulated the design of standard optical-fiber communication systems to replace wire carriers by the early 1980's. In other characteristics, i.e., counting rate, pulse-height resolution, effective quantum efficiency, detection efficiency, and reliability, bare APDs are equivalent to standard PMTs. APDs with currently available amplifiers cannot resolve single photoelectrons but they could provide reasonable detection efficiencies and pulse-height resolution for packets of approx. > 100 photons. Commercially available APDs can cost up to 100 times as much as PMTs per active area, but they are potentially much cheaper. Six topics are discussed: (1) detectors for light-wave communication and detectors for particles, (2) avalanche photodiodes, (3) commercially available APDs, (4) dynamic response of PMTs and bare APDs, (5) photon counting with cold APDs, and (6) conclusions and recommendations

Changes in low-frequency fluctuations in patients with antisocial personality disorder revealed by resting-state functional MRI.

Directory of Open Access Journals (Sweden)

Huasheng Liu

Full Text Available Antisocial Personality Disorder (APD is a personality disorder that is most commonly associated with the legal and criminal justice systems. The study of the brain in APD has important implications in legal contexts and in helping ensure social stability. However, the neural contribution to the high prevalence of APD is still unclear. In this study, we used resting-state functional magnetic resonance imaging (fMRI to investigate the underlying neural mechanisms of APD. Thirty-two healthy individuals and thirty-five patients with APD were recruited. The amplitude of low-frequency fluctuations (ALFF was analyzed for the whole brain of all subjects. Our results showed that APD patients had a significant reduction in the ALFF in the right orbitofrontal cortex, the left temporal pole, the right inferior temporal gyrus, and the left cerebellum posterior lobe compared to normal controls. We observed that the right orbitofrontal cortex had a negative correlation between ALFF values and MMPI psychopathic deviate scores. Alterations in ALFF in these specific brain regions suggest that APD patients may be associated with abnormal activities in the fronto-temporal network. We propose that our results may contribute in a clinical and forensic context to a better understanding of APD.

Guaranteed performance in reaching mode of sliding mode ...

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

addresses the design of constant plus proportional rate reaching law-based SMC for second-order ... Reaching mode; sliding mode controlled systems; output tracking ... The uncertainty in the input distribution function g is expressed as.

Brief cognitive therapy for avoidant personality disorder.

Science.gov (United States)

Rees, Clare S; Pritchard, Rhian

2015-03-01

Avoidant personality disorder (APD) is associated with a high level of impairment in multiple areas of functioning. However, research on the treatment of APD is scarce, and there is an absence of empirically evaluated effective treatment approaches available. This study offers a preliminary investigation of the use of brief cognitive therapy to treat APD. Two individuals, both with a principal diagnosis of APD, but who also possessed a number of comorbidities, participated in 12 weekly sessions. A series of diagnostic symptom severity, global functioning, and self-report measures were completed at pretreatment, posttreatment and at 6-week follow-up. In addition, regular monitoring of each participant's strength of belief in 4 personally identified cognitions associated with APD was completed. Reductions in APD symptoms, associated negative affect, and increases to quality of life were observed for both participants at posttreatment and follow-up phases. Results suggest that brief cognitive therapy may be an effective treatment for APD and that further studies with larger samples are warranted. (PsycINFO Database Record (c) 2015 APA, all rights reserved).

Avoidant personality disorder and its relationship to social phobia.

Science.gov (United States)

Reich, James

2009-02-01

This review summarizes past and recent findings in the empiric literature and the evolution of the concepts of avoidant personality disorder (APD) and social phobia (SP). APD is an internally consistent dimensional personality pathology that causes dysfunction that appears to be dimensional rather than a sudden jump in impairment after a certain number of criteria have been met. It has state and trait personality components. Evidence indicates that symptoms are at least partially treatable with psychological or pharmacologic interventions. APD and SP have similar symptoms and treatment response and identical genetics. We can conclude from the empiric evidence that no dividing line exists between APD and SP, with APD merely being the more severe form of the disorder. The best conceptualization is that APD is a dimensional personality pathology that in its attenuated form (SP) resembles an anxiety disorder.

Monopole search with the Frejus tunnel nucleon lifetime experiment

International Nuclear Information System (INIS)

Eschstruth, P.

1984-01-01

This chapter describes the detection of Grand Unified Theory (GUT) monopoles using a 1000 ton instrument consisting of a fine-grain flash-tube calorimeter and a trigger system using Geiger tubes. The orientation of the flash tubes is alternately horizontal and vertical by pairs, while that of the Geiger tubes changes from one module to the next. The trigger electronics for the nucleon lifetime experiment sums clipped signals from groups of adjacent Geiger planes requiring the coincidence of a given number of tubes within the group

High-mode-number ballooning modes in a heliotron/torsatron system. II. Stability

International Nuclear Information System (INIS)

Nakajima, N.

1996-01-01

In heliotron/torsatron systems that have a large Shafranov shift, the local magnetic shear is found to have no stabilizing effect on high-mode-number ballooning modes at the outer side of the torus, even in the region where the global shear is stellarator-like in nature. The disappearance of this stabilization, in combination with the compression of the flux surfaces at the outer side of the torus, leads at relatively low values of the plasma pressure to significant modifications of the stabilizing effect due to magnetic field-line bending on high-mode-number ballooning modes-specifically, that the field-line bending stabilization can be remarkably suppressed or enhanced. In an equilibrium that is slightly Mercier-unstable or completely Mercier-stable due to peaked pressure profiles, such as those used in standard stability calculations, high-mode-number ballooning modes are destabilized due to these modified stability effects, with their eigenfunctions highly localized along the field line. Highly localized mode structures such as these cause the ballooning mode eigenvalues ω 2 to have a strong field line dependence (i.e., α-variation) through the strong dependence of the local magnetic curvature, such that the level surfaces of ω 2 (ψ,θ k ,α) (≤0) become spheroids in (ψ,θ k ,α) space, where ψ labels flux surfaces and θ k is the radial wave number. Because the spheroidal level surfaces for unstable eigenvalues are surrounded by level surfaces for stable eigenvalues of high-mode-number toroidal Alfvacute en eigenmodes, those high-mode-number ballooning modes never lead to low-mode-number modes. In configuration space, these high-mode-number modes are localized in a single toroidal pitch of the helical coils, and hence they may experience substantial stabilization due to finite Larmor radius effects. copyright 1996 American Institute of Physics

Edge-localized mode avoidance and pedestal structure in I-mode plasmas

Energy Technology Data Exchange (ETDEWEB)

Walk, J. R., E-mail: jrwalk@psfc.mit.edu; Hughes, J. W.; Hubbard, A. E.; Terry, J. L.; Whyte, D. G.; White, A. E.; Baek, S. G.; Reinke, M. L.; Theiler, C.; Churchill, R. M.; Rice, J. E. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139-4307 (United States); Snyder, P. B.; Osborne, T. [General Atomics, San Diego, CA 92186-5608 (United States); Dominguez, A [Princeton Plasma Physics Laboratory, Princeton, NJ 08543-0451 (United States); Cziegler, I. [UCSD Center for Momentum Transport and Flow Organization, La Jolla, CA 92093-0417 (United States)

2014-05-15

I-mode is a high-performance tokamak regime characterized by the formation of a temperature pedestal and enhanced energy confinement, without an accompanying density pedestal or drop in particle and impurity transport. I-mode operation appears to have naturally occurring suppression of large Edge-Localized Modes (ELMs) in addition to its highly favorable scalings of pedestal structure and overall performance. Extensive study of the ELMy H-mode has led to the development of the EPED model, which utilizes calculations of coupled peeling-ballooning MHD modes and kinetic-ballooning mode (KBM) stability limits to predict the pedestal structure preceding an ELM crash. We apply similar tools to the structure and ELM stability of I-mode pedestals. Analysis of I-mode discharges prepared with high-resolution pedestal data from the most recent C-Mod campaign reveals favorable pedestal scalings for extrapolation to large machines—pedestal temperature scales strongly with power per particle P{sub net}/n{sup ¯}{sub e}, and likewise pedestal pressure scales as the net heating power (consistent with weak degradation of confinement with heating power). Matched discharges in current, field, and shaping demonstrate the decoupling of energy and particle transport in I-mode, increasing fueling to span nearly a factor of two in density while maintaining matched temperature pedestals with consistent levels of P{sub net}/n{sup ¯}{sub e}. This is consistent with targets for increased performance in I-mode, elevating pedestal β{sub p} and global performance with matched increases in density and heating power. MHD calculations using the ELITE code indicate that I-mode pedestals are strongly stable to edge peeling-ballooning instabilities. Likewise, numerical modeling of the KBM turbulence onset, as well as scalings of the pedestal width with poloidal beta, indicates that I-mode pedestals are not limited by KBM turbulence—both features identified with the trigger for large ELMs

Low-bending loss and single-mode operation in few-mode optical fiber

Science.gov (United States)

Yin, Ping; Wang, Hua; Chen, Ming-Yang; Wei, Jin; Cai, Zhi-Min; Li, Lu-Ming; Yang, Ji-Hai; Zhu, Yuan-Feng

2016-10-01

The technique of eliminating the higher-order modes in a few-mode optical fiber is proposed. The fiber is designed with a group of defect modes in the cladding. The higher-order modes in the fiber can be eliminated by bending the fiber to induce strong coupling between the defect modes and the higher-order modes. Numerical simulation shows the bending losses of the LP01 mode are lower than 1.5×10-4 dB/turn for the wavelength shorter than 1.625 μm. The proposed fiber can be bent multiple turns at small bending radius which are preferable for FTTH related applications.

Plasma Modes

Science.gov (United States)

Dubin, D. H. E.

This chapter explores several aspects of the linear electrostatic normal modes of oscillation for a single-species non-neutral plasma in a Penning trap. Linearized fluid equations of motion are developed, assuming the plasma is cold but collisionless, which allow derivation of the cold plasma dielectric tensor and the electrostatic wave equation. Upper hybrid and magnetized plasma waves in an infinite uniform plasma are described. The effect of the plasma surface in a bounded plasma system is considered, and the properties of surface plasma waves are characterized. The normal modes of a cylindrical plasma column are discussed, and finally, modes of spheroidal plasmas, and finite temperature effects on the modes, are briefly described.

Auditory Processing Disorders

Science.gov (United States)

... many processes and problems contribute to APD in children. In adults, neurological disorders such as stroke, tumors, degenerative disease (such as multiple sclerosis), and head trauma can contribute to APD. APD in children and adults often is best managed by a ...

An automatic mode-locked system for passively mode-locked fiber laser

Science.gov (United States)

Li, Sha; Xu, Jun; Chen, Guoliang; Mei, Li; Yi, Bo

2013-12-01

This paper designs and implements one kind of automatic mode-locked system. It can adjust a passively mode-locked fiber laser to keep steady mode-locked states automatically. So the unsteadiness of traditional passively mode-locked fiber laser can be avoided. The system transforms optical signals into electrical pulse signals and sends them into MCU after processing. MCU calculates the frequency of the signals and judges the state of the output based on a quick judgment algorithm. A high-speed comparator is used to check the signals and the comparison voltage can be adjusted to improve the measuring accuracy. Then by controlling two polarization controllers at an angle of 45degrees to each other, MCU extrudes the optical fibers to change the polarization until it gets proper mode-locked output. So the system can continuously monitor the output signal and get it back to mode-locked states quickly and automatically. States of the system can be displayed on the LCD and PC. The parameters of the steady mode-locked states can be stored into an EEPROM so that the system will get into mode-locked states immediately next time. Actual experiments showed that, for a 6.238MHz passively mode-locked fiber lasers, the system can get into steady mode-locked states automatically in less than 90s after starting the system. The expected lock time can be reduced to less than 20s after follow up improvements.

Stability of longitudinal modes in a bunched beam with mode coupling

International Nuclear Information System (INIS)

Satoh, K.

1981-06-01

In this paper we study a longitudinal coherent bunch instability in which the growth time is comparable to or less than the period of synchrotron oscillations. Both longitudinal and transverse bunch instabilities have been studied. In most treatments, however, the coherent force is assumed to be small and is treated as a perturbation compared with the synchrotron force. This makes the problem simpler because an individual synchrotron mode is decoupled. As bunch current increases, the coherent force is no longer small and the mode frequency shift becomes significant compared with the synchrotron frequency. Therefore in this case it is necessary to include coupling of the synchrotron modes. Recently a fast blow-up instability which comes from mode coupling was studied. Their method is to derive a dispersion relation for a bunched beam using the Vlasov equation and to analyze it as in a coasting beam. They showed that if mode coupling is included the Vlasov equation predicts a fast microwave instability with a stability condition similar to that for a coasting beam. In this paper we will partly follow their method and present a formalism which includes coupling between higher-order radial modes as well as coupling between synchrotron modes. The formalism is considered to be generalization of the Sacherer formalism without mode coupling. This theory predicts that instability is induced not only by coupling between different synchrotron modes, but also by coupling between positive and negative modes, since negative synchrotron modes are included in the theory in a natural manner. This formalism is to be used for a Gaussian bunch and a parabolic bunch, and is also useful for transverse problems

Superior survival of high transporters treated with automated versus continuous ambulatory peritoneal dialysis.

Science.gov (United States)

Johnson, David W; Hawley, Carmel M; McDonald, Stephen P; Brown, Fiona G; Rosman, Johan B; Wiggins, Kathryn J; Bannister, Kym M; Badve, Sunil V

2010-06-01

Automated peritoneal dialysis (APD) is widely recommended for the management of high transporters by the International Society of Peritoneal Dialysis (ISPD), although there have been no adequate studies to date comparing the outcomes of APD and continuous ambulatory peritoneal dialysis (CAPD) in this high risk group. The relative impact of APD versus CAPD on patient and technique survival rates was examined by both intention-to-treat (PD modality at Day 90) and 'as-treated' time-varying Cox proportional hazards model analyses in all patients who started PD in Australia or New Zealand between 1 April 1999 and 31 March 2004 and who had baseline peritoneal equilibration tests confirming the presence of high peritoneal transport status. During the study period, 4128 patients commenced PD. Of these, 628 patients were high transporters on PD at Day 90 (486 on APD and 142 on CAPD). Compared to high transporters treated with CAPD, APD-treated high transporters were more likely to be younger and Caucasian, and less likely to be diabetic. On multivariate intention-to-treat analysis, APD treatment was associated with superior survival [adjusted hazard ratio (HR) 0.56, 95% confidence interval (CI) 0.35-0.87] and comparable death-censored technique survival (HR 0.88, 95% CI 0.64-1.21). Superior survival of high transporters treated with APD versus CAPD was also confirmed in supplemental as-treated analysis (HR 0.72, 95% CI 0.54-0.96), matched case-control analysis (HR 0.60, 95% CI 0.36-0.96) and subgroup analysis of high transporters treated entirely with APD versus those treated entirely with CAPD (HR 0.29, 95% CI 0.14-0.60). There were no statistically significant differences in patient survival or death-censored technique survival between APD and CAPD for any other transport group, except for low transporters, who experienced a higher mortality rate on APD compared with CAPD (HR 2.19, 95% CI 1.02-4.70). APD treatment is associated with a significant survival advantage in

Restitution slope is principally determined by steady-state action potential duration.

Science.gov (United States)

Shattock, Michael J; Park, Kyung Chan; Yang, Hsiang-Yu; Lee, Angela W C; Niederer, Steven; MacLeod, Kenneth T; Winter, James

2017-06-01

The steepness of the action potential duration (APD) restitution curve and local tissue refractoriness are both thought to play important roles in arrhythmogenesis. Despite this, there has been little recognition of the apparent association between steady-state APD and the slope of the restitution curve. The objective of this study was to test the hypothesis that restitution slope is determined by APD and to examine the relationship between restitution slope, refractoriness and susceptibility to VF. Experiments were conducted in isolated hearts and ventricular myocytes from adult guinea pigs and rabbits. Restitution curves were measured under control conditions and following intervention to prolong (clofilium, veratridine, bretylium, low [Ca]e, chronic transverse aortic constriction) or shorten (catecholamines, rapid pacing) ventricular APD. Despite markedly differing mechanisms of action, all interventions that prolonged the action potential led to a steepening of the restitution curve (and vice versa). Normalizing the restitution curve as a % of steady-state APD abolished the difference in restitution curves with all interventions. Effects on restitution were preserved when APD was modulated by current injection in myocytes pre-treated with the calcium chelator BAPTA-AM - to abolish the intracellular calcium transient. The non-linear relation between APD and the rate of repolarization of the action potential is shown to underpin the common influence of APD on the slope of the restitution curve. Susceptibility to VF was found to parallel changes in APD/refractoriness, rather than restitution slope. Steady-state APD is the principal determinant of the slope of the ventricular electrical restitution curve. In the absence of post-repolarization refractoriness, factors that prolong the action potential would be expected to steepen the restitution curve. However, concomitant changes in tissue refractoriness act to reduce susceptibility to sustained VF. Dependence on

Role of the Purkinje-Muscle Junction on the Ventricular Repolarization Heterogeneity in the Healthy and Ischemic Ovine Ventricular Myocardium

Directory of Open Access Journals (Sweden)

Marine E. Martinez

2018-06-01

Full Text Available Alteration of action potential duration (APD heterogeneity contributes to arrhythmogenesis. Purkinje-muscle junctions (PMJs present differential electrophysiological properties including longer APD. The goal of this study was to determine if Purkinje-related or myocardial focal activation modulates ventricular repolarization differentially in healthy and ischemic myocardium. Simultaneous epicardial (EPI and endocardial (ENDO optical mapping was performed on sheep left ventricular (LV wedges with intact free-running Purkinje network (N = 7. Preparations were paced on either ENDO or EPI surfaces, or the free-running Purkinje fibers (PFs, mimicking normal activation. EPI and ENDO APDs were assessed for each pacing configuration, before and after (7 min of the onset of no-flow ischemia. Experiments were supported by simulations. In control conditions, maximal APD was found at endocardial PMJ sites. We observed a significant transmural APD gradient for PF pacing with PMJ APD = 347 ± 41 ms and EPI APD = 273 ± 36 ms (p < 0.001. A similar transmural gradient was observed when pacing ENDO (49 ± 31 ms; p = 0.005. However, the gradient was reduced when pacing EPI (37 ± 20 ms; p = 0.005. Global dispersion of repolarization was the most pronounced for EPI pacing. In ischemia, both ENDO and EPI APD were reduced (p = 0.005 and the transmural APD gradient (109 ± 55 ms was increased when pacing ENDO compared to control condition or when pacing EPI (p < 0.05. APD maxima remained localized at functional PMJs during ischemia. Local repolarization dispersion was significantly higher at the PMJ than at other sites. The results were consistent with simulations. We found that the activation sequence modulates repolarization heterogeneity in the ischemic sheep LV. PMJs remain active following ischemia and exert significant influence on local repolarization patterns.

Double-mode pulsation

International Nuclear Information System (INIS)

Cox, A.N.

1982-01-01

Double mode pulsation is a very pervasive phenomenon in stars all over the Hertzsprung-Russell diagram. In order of increasing radius, examples are: ZZ Ceti stars, the sun, the delta Scuti stars, RR Lyrae variables, the β Cephei variables and those related to them, Cepheids, and maybe even the Mira stars. These many modes have been interpreted as both radial and nonradial modes, but in many cases the actual mode has not been clearly identified. Yellow giants seem to be the most simple pulsators with a large majority of the RR Lyrae variables and Cepheids showing only one pulsation period. We limit this review to those very few cases for classical Cepheids and RR Lyrae variables which display two modes. For these we know many facts about these stars, but the actual cause of the pulsation in two modes simultaneously remains unknown

The relationship between avoidant personality disorder and social phobia.

Science.gov (United States)

Hummelen, Benjamin; Wilberg, Theresa; Pedersen, Geir; Karterud, Sigmund

2007-01-01

The main explanatory hypothesis for the distinction between social phobia (SP) and avoidant personality disorder (APD) has been the severity continuum hypothesis, stating that APD only differs from SP in terms of severity of dysfunction and symptomatic distress, that is, social anxiety and depressive symptoms. This study aimed at a comprehensive evaluation of this hypothesis in a large sample (n = 2192) of thoroughly assessed patients, most of whom had a diagnosis of personality disorder. Social phobia was stronger associated with APD than with other personality disorders, and APD was stronger associated with SP than with other symptom disorders. Social phobia-pure patients had a higher level of global functioning and lower levels of general symptom distress and interpersonal problems than APD-pure patients. The 2 groups were similar on domains that pertain to social anxiety and introversion, but APD was associated with a broader array of symptoms and interpersonal problems and was substantially lower on the personality domain of conscientiousness. Avoidant personality disorder was stronger associated with eating disorders, and SP was stronger associated with panic disorder. The APD diagnosis seems to capture a broader constellation of symptoms and personality features pointing toward more severe personality dysfunction. Our findings suggest that the severity continuum hypothesis lacks specificity and exploratory power to account for both similarities and differences between SP and APD.

Comparison of peritonitis rates and patient survival in automated and continuous ambulatory peritoneal dialysis: a 10-year single center experience.

Science.gov (United States)

El-Reshaid, Wael; Al-Disawy, Hanan; Nassef, Hossameldeen; Alhelaly, Usama

2016-09-01

Peritonitis is a common complication in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) and automated peritoneal dialysis (APD). In this retrospective study, peritonitis rates and patient survival of 180 patients on CAPD and 128 patients on APD were compared in the period from January 2005 to December 2014 at Al-Nafisi Center in Kuwait. All patients had prophylactic topical mupirocin at catheter exit site. Patients on CAPD had twin bag system with Y transfer set. The peritonitis rates were 1 in 29 months in CAPD and 1 in 38 months in APD (p peritonitis free patients over 10-year period in CAPD and APD were 49 and 60%, respectively (p peritonitis was 10.25 ± 3.1 months in CAPD compared to 16.1 ± 4 months in APD (p peritonitis was 13.1 ± 1 and 14 ± 1.4 months respectively (p = 0.3) whereas in peritonitis free patients it was 15 ± 1.4 months in CAPD and 23 ± 3.1 months in APD (p = 0.025). APD had lower incidence rate of peritonitis than CAPD. Patient survival was better in APD than CAPD in peritonitis free patients but was similar in patients who had peritonitis.

Inter-comb synchronization by mode-to-mode locking

Science.gov (United States)

Chun, Byung Jae; Kim, Young-Jin; Kim, Seung-Woo

2016-08-01

Two combs of fiber femtosecond lasers are synchronized through the optical frequency reference created by injection-locking of a diode laser to a single comb mode. Maintaining a mHz-level narrow linewidth, the optical frequency reference permits two combs to be stabilized by mode-to-mode locking with a relative stability of 1.52  ×  10-16 at 10 s with a frequency slip of 2.46 mHz. This inter-comb synchronization can be utilized for applications such as dual-comb spectroscopy or ultra-short pulse synthesis without extra narrow-linewidth lasers.

The H-mode Pedestal and Edge Localized Modes in NSTX

International Nuclear Information System (INIS)

Maingi, R.; Fredrickson, E.D.; Menard, J.E.; Nishino, N.; Roquemore, A.L.; Sabbagh, S.A.; Tritz, K.

2004-01-01

The research program of the National Spherical Torus Experiment (NSTX) routinely utilizes the H-mode confinement regime to test and extend beta and pulse length limits. As in conventional aspect ratio tokamaks, NSTX observes a variety of edge localized modes (ELMs) in H-mode. Hence a significant part of the research program is dedicated to ELMs studies

A Minimal Model to Explore the Influence of Distant Modes on Mode-Coupling Instabilities

Science.gov (United States)

Kruse, Sebastian; Hoffmann, Norbert

2010-09-01

The phenomenon of mode-coupling instability is one of the most frequently explored mechanisms to explain self-excited oscillation in sliding systems with friction. A mode coupling instability is usually due to the coupling of two modes. However, further modes can have an important influence on the coupling of two modes. This work extends a well-known minimal model to describe mode-coupling instabilities in order to explore the influence of a distant mode on the classical mode-coupling pattern. This work suggests a new minimal model. The model is explored and it is shown that a third mode can have significant influence on the classical mode-coupling instabilities where two modes are coupling. Different phenomena are analysed and it is pointed out that distant modes can only be ignored in very special cases and that the onset friction-induced oscillations can even be very sensitive to minimal variation of a distant mode. Due to the chosen academic minimal-model and the abandonment of a complex Finite-Element model the insight stays rather phenomenological but a better understanding of the mode-coupling mechnanism can be gained.

Study of micro pixel photon counters for a high granularity scintillator-based hadron calorimeter

International Nuclear Information System (INIS)

D'Ascenzo, N.; Eggemann, A.; Garutti, E.

2007-11-01

A new Geiger mode avalanche photodiode, the Micro Pixel Photon Counter (MPPC), was recently released by Hamamatsu. It has a high photo-detection efficiency in the 420 nm spectral region. This product can represent an elegant candidate for the design of a high granularity scintillator based hadron calorimeter for the International Linear Collider. In fact, the direct readout of the blue scintillation photons with a MPPC is a feasible techological solution. The readout of a plastic scintillator by a MPPC, both mediated by the traditional wavelength shifting fiber, and directly coupled, has been systematically studied. (orig.)

First results of systematic studies done with silicon photomultipliers

International Nuclear Information System (INIS)

Bosio, C.; Gentile, S.; Kuznetsova, E.; Meddi, F.

2008-01-01

Multicell avalanche photodiode structure operated in Geiger mode usually referred as silicon photomultiplier is a new intensively developing technology for photon detection. Insensitivity to magnetic fields, low operation voltage and small size make silicon photomultipliers very attractive for high-energy physics, astrophysics and medical applications. The presented results are obtained during the first steps taken in order to develop a setup and measurement procedures which allow to compare properties of diverse samples of silicon photomultipliers available on market. The response to low-intensity light was studied for silicon photomultipliers produced by CPTA (Russia), Hamamatsu (Japan), ITC-irst (Italy) and SensL (Ireland).

Antisocial Personality as a Neurodevelopmental Disorder.

Science.gov (United States)

Raine, Adrian

2018-05-07

Although antisocial personality disorder (APD) is one of the most researched personality disorders, it is still surprisingly resistant to treatment. This lack of clinical progress may be partly due to the failure to view APD as a neurodevelopmental disorder and to consider early interventions. After first defining what constitutes a neurodevelopmental disorder, this review evaluates the extent to which APD meets neurodevelopmental criteria, covering structural and functional brain imaging, neurocognition, genetics and epigenetics, neurochemistry, and early health risk factors. Prevention and intervention strategies for APD are then outlined, focusing on addressing early biological and health systems, followed by forensic and clinical implications. It is argued both that APD meets criteria for consideration as a neurodevelopmental disorder and that consideration should be given both to the possibility that early onset conduct disorder is neurodevelopmental in nature, and also to the inclusion of psychopathy as a specifier in future Diagnostic and Statistical Manual revisions of APD.

Speed and accuracy of facial expression classification in avoidant personality disorder: a preliminary study.

Science.gov (United States)

Rosenthal, M Zachary; Kim, Kwanguk; Herr, Nathaniel R; Smoski, Moria J; Cheavens, Jennifer S; Lynch, Thomas R; Kosson, David S

2011-10-01

The aim of this preliminary study was to examine whether individuals with avoidant personality disorder (APD) could be characterized by deficits in the classification of dynamically presented facial emotional expressions. Using a community sample of adults with APD (n = 17) and non-APD controls (n = 16), speed and accuracy of facial emotional expression recognition was investigated in a task that morphs facial expressions from neutral to prototypical expressions (Multi-Morph Facial Affect Recognition Task; Blair, Colledge, Murray, & Mitchell, 2001). Results indicated that individuals with APD were significantly more likely than controls to make errors when classifying fully expressed fear. However, no differences were found between groups in the speed to correctly classify facial emotional expressions. The findings are some of the first to investigate facial emotional processing in a sample of individuals with APD and point to an underlying deficit in processing social cues that may be involved in the maintenance of APD.

Towards on-chip integration of brain imaging photodetectors using standard CMOS process.

Science.gov (United States)

Kamrani, Ehsan; Lesage, Frederic; Sawan, Mohamad

2013-01-01

The main effects of on-chip integration on the performance and efficiency of silicon avalanche photodiode (SiAPD) and photodetector front-end is addressed in this paper based on the simulation and fabrication experiments. Two different silicon APDs are fabricated separately and also integrated with a transimpedance amplifier (TIA) front-end using standard CMOS technology. SiAPDs are designed in p+/n-well structure with guard rings realized in different shapes. The TIA front-end has been designed using distributed-gain concept combined with resistive-feedback and common-gate topology to reach low-noise and high gain-bandwidth product (GBW) characteristics. The integrated SiAPDs show higher signal-to-noise ratio (SNR), sensitivity and detection efficiency comparing to the separate SiAPDs. The integration does not show a significant effect on the gain and preserves the low power consumption. Using APDs with p-well guard-ring is preferred due to the higher observed efficiency after integration.

Accurate mode characterization of two-mode optical fibers by in-fiber acousto-optics.

Science.gov (United States)

Alcusa-Sáez, E; Díez, A; Andrés, M V

2016-03-07

Acousto-optic interaction in optical fibers is exploited for the accurate and broadband characterization of two-mode optical fibers. Coupling between LP 01 and LP 1m modes is produced in a broadband wavelength range. Difference in effective indices, group indices, and chromatic dispersions between the guided modes, are obtained from experimental measurements. Additionally, we show that the technique is suitable to investigate the fine modes structure of LP modes, and some other intriguing features related with modes' cut-off.

Mode-mode coupling theory of itinerant electron antiferromagnetism in superconducting state

International Nuclear Information System (INIS)

Fujimoto, Yukinobu; Miyake, Kazumasa

2012-01-01

It has been considered since the first discovery of a high-T c cuprate that an antiferromagnetic (AF) state and a superconducting (SC) state are separated in it. However, it is very intriguing that the coexistence of the AF and SC states has recently been observed in HgBa 2 Ca 4 Cu 5 O 12+ (Hg-1245). Moreover, it is very novel that this coexistence of these two states appears if the SC-transition temperature T c is higher than the AF-transition temperature T N . The mode-mode coupling theory can provide a clear elucidation of this novel phenomenon. A key point of this theory is that the AF susceptibility consists of the random-phase-approximation (RPA) term and the mode-mode coupling one. The RPA term works to make a positive contribution to the emergence of the antiferromagnetic critical point (AF-CP). In contrast, the mode-mode coupling term works to make a negative contribution to the emergence of the AF-CP. However, the growth of the SC-gap function in the d x 2 -y 2 -wave SC state works to suppress the negative contribution of the mode-mode coupling term to the emergence of the AF-CP. Moreover, the effect of SC fluctuations near the SC-transition temperature T c suppresses the mode-mode coupling term of the AF susceptibility that works to hinder the AF ordering. For these two reasons, there is a possibility that the d x 2 -y 2 -wave SC state is likely to promote the emergence of the AF-CP. Namely, the appearance of the above-mentioned novel coexistence of the AF and SC states observed in Hg-1245 can be explained qualitatively on the basis of this idea.

A comprehensive spectral theory of zonal-mode dynamics in trapped electron mode turbulence

International Nuclear Information System (INIS)

Terry, P.W.; Gatto, R.; Baver, D.A.; Fernandez, E.

2005-01-01

A comprehensive, self-consistent theory for spectral dynamics in trapped electron mode (TEM) turbulence offers critical new understanding and insights into zonal-mode physics. This theory shows that 1) zonal mode structure, anisotropy, excitation, and temporal behavior arise at and from the interface of nonlinear advection and linear wave properties; 2) waves induce a marked spectral energy-transfer anisotropy that preferentially drives zonal modes relative to non zonal modes; 3) triplet correlations involving density (as opposed to those involving only flow) mediate the dominant energy transfer at long wavelengths; 4) energy transfer becomes inverse in the presence of wave anisotropy, where otherwise it is forward; 5) zonal-mode excitation is accompanied by excitation of a spectrum of damped eigenmodes, making zonal modes nonlinearly damped; and 6) the combination of anisotropic transfer to zonal modes and their nonlinear damping make this the dominant saturation mechanism for TEM turbulence. This accounts for the reduction of turbulence level by zonal modes, not zonal-flow ExB shearing. (author)

Electrophysiologic effects of the IK1 inhibitor PA-6 are modulated by extracellular potassium in isolated guinea pig hearts

DEFF Research Database (Denmark)

Hoeker, Gregory S; Skarsfeldt, Mark A; Jespersen, Thomas

2017-01-01

in Langendorff-perfused guinea pig hearts. PA-6 (200 nm) or vehicle was perfused into ex-vivo guinea pig hearts for 60 min. Hearts were optically mapped with di-4-ANEPPS to quantify CV and APD at 90% repolarization (APD90). Ventricular APD90was significantly prolonged in hearts treated with PA-6 (115 ± 2...... APD90to a lesser degree, but profoundly increased CV Thus, in intact guinea pig hearts, the electrophysiologic effects of the IK1inhibitor, PA-6, are [K+]o-dependent....

Acquired perforating dermatosis: a report of 8 cases.

Science.gov (United States)

González-Lara, L; Gómez-Bernal, S; Vázquez-López, F; Vivanco-Allende, B

2014-01-01

Acquired perforating dermatosis (APD) is an uncommon disease characterized by lesions exhibiting transepidermal elimination of collagen or elastic fibers. APD affects adults and is associated with systemic diseases, mainly diabetes mellitus and renal failure. We present 8 cases of APD. Seven patients had concomitant diabetes mellitus with or without chronic renal failure, and 1 had alcoholic cirrhosis. In the patients with chronic renal failure, the onset of APD coincided with transient worsening of renal function. The mean increase in creatinine concentrations above baseline was 1.14mg/dL. Acute deterioration of renal function may be involved in APD. Further studies are needed to investigate this association. Copyright © 2013 Elsevier España, S.L. y AEDV. All rights reserved.

Modes and Mode Volumes for Leaky Optical Cavities and Plasmonic Nanoresonators

DEFF Research Database (Denmark)

Hughes, Stephen; Kristensen, Philip Trøst

2013-01-01

Electromagnetic cavity modes in photonic and plasmonic resonators offer rich and attractive regimes for tailoring the properties of light–matter interactions, yet there is a disturbing lack of a precise definition for what constitutes a cavity mode, and as a result their mathematical properties r...... methods for quasinormal modes of both photonic and plasmonic resonators and the concept of a generalized effective mode volume, and we illustrate the theory with several representative cavity structures from the fields of photonic crystals and nanoplasmonics....

Disease Evolution and Response to Rapamycin in Activated Phosphoinositide 3-Kinase δ Syndrome: The European Society for Immunodeficiencies-Activated Phosphoinositide 3-Kinase δ Syndrome Registry

Directory of Open Access Journals (Sweden)

Maria Elena Maccari

2018-03-01

Full Text Available Activated phosphoinositide 3-kinase (PI3K δ Syndrome (APDS, caused by autosomal dominant mutations in PIK3CD (APDS1 or PIK3R1 (APDS2, is a heterogeneous primary immunodeficiency. While initial cohort-descriptions summarized the spectrum of clinical and immunological manifestations, questions about long-term disease evolution and response to therapy remain. The prospective European Society for Immunodeficiencies (ESID-APDS registry aims to characterize the disease course, identify outcome predictors, and evaluate treatment responses. So far, 77 patients have been recruited (51 APDS1, 26 APDS2. Analysis of disease evolution in the first 68 patients pinpoints the early occurrence of recurrent respiratory infections followed by chronic lymphoproliferation, gastrointestinal manifestations, and cytopenias. Although most manifestations occur by age 15, adult-onset and asymptomatic courses were documented. Bronchiectasis was observed in 24/40 APDS1 patients who received a CT-scan compared with 4/15 APDS2 patients. By age 20, half of the patients had received at least one immunosuppressant, but 2–3 lines of immunosuppressive therapy were not unusual before age 10. Response to rapamycin was rated by physician visual analog scale as good in 10, moderate in 9, and poor in 7. Lymphoproliferation showed the best response (8 complete, 11 partial, 6 no remission, while bowel inflammation (3 complete, 3 partial, 9 no remission and cytopenia (3 complete, 2 partial, 9 no remission responded less well. Hence, non-lymphoproliferative manifestations should be a key target for novel therapies. This report from the ESID-APDS registry provides comprehensive baseline documentation for a growing cohort that will be followed prospectively to establish prognostic factors and identify patients for treatment studies.

Nonlinear mode coupling in rotating stars and the r-mode instability in neutron stars

International Nuclear Information System (INIS)

Schenk, A.K.; Arras, P.; Flanagan, E.E.; Teukolsky, S.A.; Wasserman, I.

2002-01-01

We develop the formalism required to study the nonlinear interaction of modes in rotating Newtonian stars, assuming that the mode amplitudes are only mildly nonlinear. The formalism is simpler than previous treatments of mode-mode interactions for spherical stars, and simplifies and corrects previous treatments for rotating stars. At linear order, we elucidate and extend slightly a formalism due to Schutz, show how to decompose a general motion of a rotating star into a sum over modes, and obtain uncoupled equations of motion for the mode amplitudes under the influence of an external force. Nonlinear effects are added perturbatively via three-mode couplings, which suffices for moderate amplitude modal excitations; the formalism is easy to extend to higher order couplings. We describe a new, efficient way to compute the modal coupling coefficients, to zeroth order in the stellar rotation rate, using spin-weighted spherical harmonics. The formalism is general enough to allow computation of the initial trends in the evolution of the spin frequency and differential rotation of the background star. We apply this formalism to derive some properties of the coupling coefficients relevant to the nonlinear interactions of unstable r modes in neutron stars, postponing numerical integrations of the coupled equations of motion to a later paper. First, we clarify some aspects of the expansion in stellar rotation frequency Ω that is often used to compute approximate mode functions. We show that, in zero-buoyancy stars, the rotational modes (those modes whose frequencies vanish as Ω→0) are orthogonal to zeroth order in Ω. From an astrophysical viewpoint, the most interesting result of this paper is that many couplings of r modes to other rotational modes are small: either they vanish altogether because of various selection rules, or they vanish to lowest order in Ω or in compressibility. In particular, in zero-buoyancy stars, the coupling of three r modes is forbidden

Mode group specific amplification length in an asymmetric LPG assisted few-mode EDFA

Science.gov (United States)

Rastogi, Vipul; Gaur, Ankita; Aschieri, Pierre; Dussardier, Bernard

2017-01-01

This article presents a scheme for few-mode EDFA, which allows to choose independent amplification lengths for different mode groups. The EDF is a dual concentric core fiber, where the central core is connected to the line FMF and the ring core is doped with erbium to provide amplification. The modes of FMF are launched into the central core of the EDF, are converted into ring modes using LPG for amplification and then converted back into central core modes using another LPG. The distance between the LPGs determines the amplification length. The amplification length, can thus, be chosen for a given mode group. We demonstrate the working of this concept by choosing LP11 and LP21 mode groups of the FMF and show that a suitable choice of amplification lengths for the two mode groups can tailor the differential modal gain (DMG) to any desired value. We demonstrate achieving zero DMG among all the mode of LP11 and LP21 mode groups using this concept while having gain in excess of 20 dB. The study should be useful for optical fiber communication system employing space-division multiplexing (SDM).

Dual-Mode Combustor

Science.gov (United States)

Trefny, Charles J (Inventor); Dippold, Vance F (Inventor)

2013-01-01

A new dual-mode ramjet combustor used for operation over a wide flight Mach number range is described. Subsonic combustion mode is usable to lower flight Mach numbers than current dual-mode scramjets. High speed mode is characterized by supersonic combustion in a free-jet that traverses the subsonic combustion chamber to a variable nozzle throat. Although a variable combustor exit aperture is required, the need for fuel staging to accommodate the combustion process is eliminated. Local heating from shock-boundary-layer interactions on combustor walls is also eliminated.

A Time-Based Front End Readout System for PET & CT

CERN Document Server

Meyer, T C; Anghinolfi, F; Auffray, E; Dosanjh, M; Hillemanns, H; Hoffmann, H -F; Jarron, P; Kaplon, J; Kronberger, M; Lecoq, P; Moraes, D; Trummer, J

2007-01-01

In the framework of the European FP6's BioCare project, we develop a novel, time-based, photo-detector readout technique to increase sensitivity and timing precision for molecular imaging in PET and CT. The project aims to employ Avalanche Photo Diode (APD) arrays with state of the art, high speed, front end amplifiers and discrimination circuits developed for the Large Hadron Collider (LHC) physics program at CERN, suitable to detect and process photons in a combined one-unit PET/CT detection head. In the so-called time-based approach our efforts focus on the system's timing performance with sub-nanosecond time-jitter and -walk, and yet also provide information on photon energy without resorting to analog to digital conversion. The bandwidth of the electronic circuitry is compatible with the scintillator's intrinsic light response (e.g. les40ns in LSO) and hence allows high rate CT operation in single-photon counting mode. Based on commercial LSO crystals and Hamamatsu S8550 APD arrays, we show the system pe...

Myocardial remodeling and bioelectric changes in tachycardia-induced heart failure in dogs

Energy Technology Data Exchange (ETDEWEB)

Song, B.; Wang, B.N.; Chen, D.N.; Luo, Z.G. [Department of Cardiovascular Medicine, The First Affiliated Hospital, Anhui Medical University, HeFei, Anhui Province (China)

2013-09-06

In this study, electrical and structural remodeling of ventricles was examined in tachycardia-induced heart failure (HF). We studied two groups of weight-matched adult male mongrel dogs: a sham-operated control group (n=5) and a pacing group (n=5) that underwent ventricular pacing at 230 bpm for 3 weeks. Clinical symptoms of congestive HF were observed in both groups. Their hemodynamic parameters were determined and the severity of the HF was evaluated by M-mode echocardiography. Changes in heart morphology were observed by scanning electron and light microscopy. Ventricular action potential duration (APD), as well as the 50 and 90% APD were measured in both groups. All dogs exhibited clinical symptoms of congestive HF after rapid right ventricular pacing for 3 weeks. These data indicate that rapid, right ventricular pacing produces a useful experimental model of low-output HF in dogs, characterized by biventricular pump dysfunction, biventricular cardiac dilation, and non-ischemic impairment of left ventricular contractility. Electrical and structural myocardial remodeling play an essential role in congestive HF progression, and should thus be prevented.

Study on the energy dependence of gamma radiation detectors for 137Cs and 60Co

International Nuclear Information System (INIS)

Nonato, Fernanda B.C.; Diniz, Raphael E.; Carvalho, Valdir S.; Vivolo, Vitor; Caldas, Linda V.E.

2009-01-01

38 Geiger-Mueller radiation detectors and 9 ionization chambers were calibrated, viewing to study the energy dependence of the monitor response for gamma radiation fields ( 137 Cs and 60 Co). The results were considered satisfactory only for ionization chambers and for some Geiger-Mueller detectors

Sliding mode control and observation

CERN Document Server

Shtessel, Yuri; Fridman, Leonid; Levant, Arie

2014-01-01

The sliding mode control methodology has proven effective in dealing with complex dynamical systems affected by disturbances, uncertainties and unmodeled dynamics. Robust control technology based on this methodology has been applied to many real-world problems, especially in the areas of aerospace control, electric power systems, electromechanical systems, and robotics. Sliding Mode Control and Observation represents the first textbook that starts with classical sliding mode control techniques and progresses toward newly developed higher-order sliding mode control and observation algorithms and their applications. The present volume addresses a range of sliding mode control issues, including: *Conventional sliding mode controller and observer design *Second-order sliding mode controllers and differentiators *Frequency domain analysis of conventional and second-order sliding mode controllers *Higher-order sliding mode controllers and differentiators *Higher-order sliding mode observers *Sliding mode disturbanc...

Avoidant personality disorder is a separable schizophrenia-spectrum personality disorder even when controlling for the presence of paranoid and schizotypal personality disorders The UCLA family study.

Science.gov (United States)

Fogelson, D L; Nuechterlein, K H; Asarnow, R A; Payne, D L; Subotnik, K L; Jacobson, K C; Neale, M C; Kendler, K S

2007-03-01

It is unresolved whether avoidant personality disorder (APD) is an independent schizophrenia (Sz)-spectrum personality disorder (PD). Some studies find APD and social anxiety symptoms (Sxs) to be separable dimensions of psychopathology in relatives (Rels) of schizophrenics while other studies find avoidant Sxs to be correlated with schizotypal and paranoid Sxs. Rates of APD among first-degree Rels of Sz probands, attention-deficit/hyperactivity disorder (ADHD) probands, and community control (CC) probands were examined. Further analyses examined rates when controlling for the presence of schizotypal (SPD) and paranoid (PPD) personality disorders, differences in APD Sxs between relative groups, and whether APD in Rels of Szs reflects a near miss for another Sz-spectrum PD. Three hundred sixty-two first-degree Rels of Sz probands, 201 relatives of ADHD probands, and 245 Rels of CC probands were interviewed for the presence of DSM-III-R Axis I and II disorders. Diagnoses, integrating family history, interview information, and medical records, were determined. APD occurred more frequently in Rels of Sz probands compared to CC probands (pavoids social or occupational activities..." and "exaggerates the potential difficulties..." 65% of the Rels of Sz probands who had diagnoses of APD were more than one criterion short of a DSM-III-R diagnosis of either SPD or PPD. This indicates that APD is a separate Sz-spectrum disorder, and not merely a sub-clinical form of SPD or PPD.

Ventricular action potential adaptation to regular exercise: role of β-adrenergic and KATP channel function.

Science.gov (United States)

Wang, Xinrui; Fitts, Robert H

2017-08-01

Regular exercise training is known to affect the action potential duration (APD) and improve heart function, but involvement of β-adrenergic receptor (β-AR) subtypes and/or the ATP-sensitive K + (K ATP ) channel is unknown. To address this, female and male Sprague-Dawley rats were randomly assigned to voluntary wheel-running or control groups; they were anesthetized after 6-8 wk of training, and myocytes were isolated. Exercise training significantly increased APD of apex and base myocytes at 1 Hz and decreased APD at 10 Hz. Ca 2+ transient durations reflected the changes in APD, while Ca 2+ transient amplitudes were unaffected by wheel running. The nonselective β-AR agonist isoproterenol shortened the myocyte APD, an effect reduced by wheel running. The isoproterenol-induced shortening of APD was largely reversed by the selective β 1 -AR blocker atenolol, but not the β 2 -AR blocker ICI 118,551, providing evidence that wheel running reduced the sensitivity of the β 1 -AR. At 10 Hz, the K ATP channel inhibitor glibenclamide prolonged the myocyte APD more in exercise-trained than control rats, implicating a role for this channel in the exercise-induced APD shortening at 10 Hz. A novel finding of this work was the dual importance of altered β 1 -AR responsiveness and K ATP channel function in the training-induced regulation of APD. Of physiological importance to the beating heart, the reduced response to adrenergic agonists would enhance cardiac contractility at resting rates, where sympathetic drive is low, by prolonging APD and Ca 2+ influx; during exercise, an increase in K ATP channel activity would shorten APD and, thus, protect the heart against Ca 2+ overload or inadequate filling. NEW & NOTEWORTHY Our data demonstrated that regular exercise prolonged the action potential and Ca 2+ transient durations in myocytes isolated from apex and base regions at 1-Hz and shortened both at 10-Hz stimulation. Novel findings were that wheel running shifted the �

The use of active personal dosemeters as a personal monitoring device: Comparison with TL dosimetry

International Nuclear Information System (INIS)

Boziari, A.; Koukorava, C.; Carinou, E.; Hourdakis, C. J.; Kamenopoulou, V.

2011-01-01

The use of active personal dosemeters (APDs) not only as a warning device but also, in some cases, as an official and hence stand-alone dosemeter is rapidly increasing. A comparison in terms of dose, energy and angle dependence, among different types of APD and a routinely used whole-body thermoluminescence dosemeter (TLD) has been performed. Significant differences were found between the TLD readings and mainly some not commonly used APDs. The importance of choosing the best adapted APD according to the radiation field characteristics is pointed out. (authors)

Spectral dependence of the main parameters of ITE silicon avalanche photodiodes

Science.gov (United States)

Wegrzecka, Iwona; Grynglas, Maria; Wegrzecki, Maciej

2001-08-01

New applications for avalanche photodiodes (APDs) as in systems using visible radiation, have prompted the need for the evaluation of detection properties of ITE APDs in the 400 divided by 700 nm spectral range. The paper presents the method and result of studies on the spectral dependence of the gain, dark and noise currents, sensitivity and excess noise factor of ITE APDs. The studies have shown that ITE APDs optimized for the near IR radiation can be effectively applied in the detection of radiation above the 500 nm wavelength.

Diagnosis and subtypes of adolescent antisocial personality disorder.

Science.gov (United States)

Jones, Meredith; Westen, Drew

2010-04-01

The present study examined the application of the Antisocial Personality Disorder (APD) diagnosis to adolescents and investigated the possibility of subtypes of APD adolescents. As part of a broader study of adolescent personality in clinically-referred patients, experienced clinicians provided personality data on a randomly selected patient in their care using the SWAP-II-A personality pathology instrument. Three hundred thirteen adolescents met adult DSM-IV diagnostic criteria for APD. To characterize adolescents with the disorder, we aggregated the data to identify the items most descriptive and distinctive of APD adolescents relative to other teenagers in the sample (N = 950). Q-factor analysis identified five personality subtypes: psychopathic-like, socially withdrawn, impulsive-histrionic, emotionally dysregulated, and attentionally dysregulated. The five subtypes differed in predictable ways on a set of external criteria related to global adaptive functioning, childhood family environment, and family history of psychiatric illness. Both the APD diagnosis and the empirically derived APD subtypes provided incremental validity over and above the DSM-IV disruptive behavior disorders in predicting global adaptive functioning, number of arrests, early-onset severe externalizing pathology, and quality of peer relationships. Although preliminary, these results provide support for the use of both APD and personality-based subtyping systems in adolescents.

Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern.

Science.gov (United States)

Schunk, Gerhard; Fürst, Josef U; Förtsch, Michael; Strekalov, Dmitry V; Vogl, Ulrich; Sedlmeir, Florian; Schwefel, Harald G L; Leuchs, Gerd; Marquardt, Christoph

2014-12-15

Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMRs. The radial mode numbers q and the angular mode numbers p = ℓ-m are identified and labeled via far-field imaging. The polar mode numbers ℓ are determined unambiguously by fitting the frequency differences between individual whispering gallery modes (WGMs). This allows for the accurate determination of the geometry and the refractive index at different temperatures of the WGMR. For future applications in classical and quantum optics, this mode analysis enables one to control the narrow-band phase-matching conditions in nonlinear processes such as second-harmonic generation or parametric down-conversion.

Study on the energy dependence of gamma radiation detectors for {sup 137}Cs and {sup 60}Co; Estudo da dependencia energetica de detectores de radiacao gama para {sup 137}Cs e {sup 60}Co

Energy Technology Data Exchange (ETDEWEB)

Nonato, Fernanda B.C.; Diniz, Raphael E.; Carvalho, Valdir S.; Vivolo, Vitor; Caldas, Linda V.E., E-mail: fbnonato@ipen.b, E-mail: rediniz@ipen.b, E-mail: vcsouza@ipen.b, E-mail: vivolo@ipen.b, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2009-07-01

38 Geiger-Mueller radiation detectors and 9 ionization chambers were calibrated, viewing to study the energy dependence of the monitor response for gamma radiation fields ({sup 137}Cs and {sup 60}Co). The results were considered satisfactory only for ionization chambers and for some Geiger-Mueller detectors

Predictions of silicon avalanche photodiode detector performance in water vapor differential absorption lidar

Science.gov (United States)

Kenimer, R. L.

1988-01-01

Performance analyses are presented which establish that over most of the range of signals expected for a down-looking differential absorption lidar (DIAL) operated at 16 km the silicon avalanche photodiode (APD) is the preferred detector for DIAL measurements of atmospheric water vapor in the 730 nm spectral region. The higher quantum efficiency of the APD's, (0.8-0.9) compared to a photomultiplier's (0.04-0.18) more than offsets the higher noise of an APD receiver. In addition to offering lower noise and hence lower random error the APD's excellent linearity and impulse recovery minimize DIAL systematic errors attributable to the detector. Estimates of the effect of detector system parameters on overall random and systematic DIAL errors are presented, and performance predictions are supported by laboratory characterization data for an APD receiver system.

Propagating annular modes

Science.gov (United States)

Sheshadri, A.; Plumb, R. A.

2017-12-01

The leading "annular mode", defined as the dominant EOF of surface pressure or of zonal mean zonal wind variability, appears as a dipolar structure straddling the mean midlatitude jet and thus seems to describe north-south wobbling of the jet latitude. However, extratropical zonal wind anomalies frequently tend to migrate poleward. This behavior can be described by the first two EOFs, the first (AM1) being the dipolar structure, and the second (AM2) having a tripolar structure centered on the mean jet. Taken in isolation, AM1 thus describes a north-south wobbling of the jet position, while AM2 describes a strengthening and narrowing of the jet. However, despite the fact that they are spatially orthogonal, and their corresponding time series temporally orthogonal, AM1 and AM2 are not independent, but show significant lag-correlations which reveal the propagation. The EOFs are not modes of the underlying dynamical system governing the zonal flow evolution. The true modes can be estimated using principal oscillation pattern (POP) analysis. In the troposphere, the leading POPs manifest themselves as a pair of complex conjugate structures with conjugate eigenvalues thus, in reality, constituting a single, complex, mode that describes propagating anomalies. Even though the principal components associated with the two leading EOFs decay at different rates, each decays faster than the true mode. These facts have implications for eddy feedback and the susceptibility of the mode to external perturbations. If one interprets the annular modes as the modes of the system, then simple theory predicts that the response to steady forcing will usually be dominated by AM1 (with the longest time scale). However, such arguments should really be applied to the true modes. Experiments with a simplified GCM show that climate response to perturbations do not necessarily have AM1 structures. Implications of these results for stratosphere-troposphere interactions are explored. The POP

A dual-mode driver IC with monolithic negative drive-voltage capability and digital current-mode controller for depletion-mode GaN HEMT

NARCIS (Netherlands)

Wen, Y.; Rose, M.; Fernandes, R.; van Otten, R.; Bergveld, H.J.; Trescases, O.

2017-01-01

This work presents a driver and controller integrated circuit (IC) for depletion-mode gallium nitride (GaN) high-electron-mobility transistors (HEMTs). The dual-mode driver can be configured for cascode-drive (CD) or HEMT-drive (HD) mode. In the CD mode, a cascode low-voltage DMOS is driven to

Observations on resistive wall modes

International Nuclear Information System (INIS)

Gerwin, R.A.; Finn, J.M.

1996-01-01

Several results on resistive wall modes and their application to tokamaks are presented. First, it is observed that in the presence of collisional parallel dynamics there is an exact cancellation to lowest order of the dissipative and sound wave effects for an ideal Ohm's law. This is easily traced to the fact that the parallel dynamics occurs along the perturbed magnetic field lines for such electromagnetic modes. Such a cancellation does not occur in the resistive layer of a tearing-like mode. The relevance to models for resistive wall modes using an electrostatic Hammett-Perkins type operator to model Landau damping will be discussed. Second, we observe that with an ideal Ohm's law, resistive wall modes can be destabilized by rotation in that part of parameter space in which the ideal MHD modes are stable with the wall at infinity. This effect can easily be explained by interpreting the resistive wall instability in terms of mode coupling between the backward stable MHD mode and a stable mode locked into the wall. Such an effect can occur for very small rotation for tearing-resistive wall modes in which inertia dominates viscosity in the layer, but the mode is stabilized by further rotation. For modes for which viscosity dominates in the layer, rotation is purely stabilizing. For both tearing models, a somewhat higher rotation frequency gives stability essentially whenever the tearing mode is stable with a perfectly conducting wall. These tearing/resistive wall results axe also simply explained in terms of mode coupling. It has been shown that resonant external ideal modes can be stabilized in the presence of resistive wall and resistive plasma with rotation of order the nominal tearing mode growth rate. We show that these modes behave as resistive wall tearing modes in the sense above. This strengthens the suggestion that rotational stabilization of the external kink with a resistive wall is due to the presence of resistive layers, even for ideal modes

Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability

DEFF Research Database (Denmark)

Laurila, Marko; Jørgensen, Mette Marie; Hansen, Kristian Rymann

2012-01-01

We demonstrate a high power fiber (85μm core) amplifier delivering up to 292Watts of average output power using a mode-locked 30ps source at 1032nm. Utilizing a single mode distributed mode filter bandgap rod fiber, we demonstrate 44% power improvement before the threshold-like onset of mode inst...

A vegetal Geiger counter

International Nuclear Information System (INIS)

Anon.

1999-01-01

In order to study the Chernobyl accident impact on ecosystems, Ukrainian and Swiss scientists have used a plant: the Arabidopsis thaliana. They have introduced in its genome a gene coding an enzyme called β-glucuronidase. This substance, when it is expressed, colours vegetal cells blue. In fact the introduced gene is divided between 2 paired chromosomes. When the plant is placed on a nuclear contaminated soil, radiation damaged chromosomes exchange fragments and the 2 parts of the enzyme gene may recombine, the enzyme can then be expressed. For low and medium contamination ( 2 ) biologists have found a correlation between the number of blue spots on the plant and the irradiation rate. (A.C.)

Assessment of children with suspected auditory processing disorder: a factor analysis study.

Science.gov (United States)

Ahmmed, Ansar U; Ahmmed, Afsara A; Bath, Julie R; Ferguson, Melanie A; Plack, Christopher J; Moore, David R

2014-01-01

To identify the factors that may underlie the deficits in children with listening difficulties, despite normal pure-tone audiograms. These children may have auditory processing disorder (APD), but there is no universally agreed consensus as to what constitutes APD. The authors therefore refer to these children as children with suspected APD (susAPD) and aim to clarify the role of attention, cognition, memory, sensorimotor processing speed, speech, and nonspeech auditory processing in susAPD. It was expected that a factor analysis would show how nonauditory and supramodal factors relate to auditory behavioral measures in such children with susAPD. This would facilitate greater understanding of the nature of listening difficulties, thus further helping with characterizing APD and designing multimodal test batteries to diagnose APD. Factor analysis of outcomes from 110 children (68 male, 42 female; aged 6 to 11 years) with susAPD on a widely used clinical test battery (SCAN-C) and a research test battery (MRC Institute of Hearing Research Multi-center Auditory Processing "IMAP"), that have age-based normative data. The IMAP included backward masking, simultaneous masking, frequency discrimination, nonverbal intelligence, working memory, reading, alerting attention and motor reaction times to auditory and visual stimuli. SCAN-C included monaural low-redundancy speech (auditory closure and speech in noise) and dichotic listening tests (competing words and competing sentences) that assess divided auditory attention and hence executive attention. Three factors were extracted: "general auditory processing," "working memory and executive attention," and "processing speed and alerting attention." Frequency discrimination, backward masking, simultaneous masking, and monaural low-redundancy speech tests represented the "general auditory processing" factor. Dichotic listening and the IMAP cognitive tests (apart from nonverbal intelligence) were represented in the "working

Combined mode I-mode II fracture of 12-mol%-ceria-doped tetragonal zirconia polycrystalline ceramic

International Nuclear Information System (INIS)

Tikare, V.; Choi, S.R.

1997-01-01

The mode I, mode II, and combined mode I-mode II fracture behavior of ceria-doped tetragonal zirconia polycrystalline (Ce-TZP) ceramic was studied. The single-edge-precracked-beam (SEPB) samples were fractured using the asymmetric four-point-bend geometry. The ratio of mode I to mode II loading was varied by varying the degree of asymmetry in the four-point-bend geometry. The minimum strain energy density theory best described the mixed-mode fracture behavior of Ce-TZP with the mode I fracture toughness, K IC = 8.2 ± 0.6 MPa·m 1/2 , and the mode II fracture toughness, K IIC = 8.6 ± 1.3 MPa·m 1/2

77 FR 66084 - Quarterly Publication of Individuals, Who Have Chosen To Expatriate, as Required by Section 6039G

Science.gov (United States)

2012-11-01

... BOUCHARD RAYMOND JOSEPH BOULLE II JEAN-RAYMOND BROMLEY MARGARET ANNE BROWNE CARLA EVELYN BRUCE JAMES TODD... CAMINOS MICHELE CLARE CAMPBELL JESSICA ANNE CHANG WAYNE WEN TIEN CHAN-PALAY VICTORIA LYE-HUA CHEN HOPE MI... RICHARD JOSEPH ARTHUR FUKUDA MEGUMI GAEHWILER YANNIK PETER GEIGER DANIEL CHRISTIAN GEIGER MICHAEL MATTHIAS...

Low-frequency modes with high toroidal mode numbers. A general formulation

International Nuclear Information System (INIS)

Pegoraro, F.; Schep, T.J.

1979-09-01

Low-frequency waves with high toroidal mode numbers in an axisymmetric toroidal configuration are studied. In particular, the relationship between the periodicity constraints imposed by the geometry, magnetic shear and the spatial structure of eigenmodes is investigated. By exploiting the radial translational invariance and the poloidal periodicity of the gyrokinetic and Maxwell equations, the two-dimensional problem can be converted into a one-dimensional one and the mode structure can be expressed in terms of a single extended poloidal variable. This representation is used in the description of electromagnetic modes with phase velocities larger than the ion thermal velocity and with frequencies below the ion gyro-frequency. Trapped particle, curvature and compressional effects are retained. The dispersion equations for drift mode and Alfven-type modes are given in general geometry and simplified solutions are presented in the configuration of a double periodic plane slab. (Auth.)

Experimental verification of microbending theory using mode coupling to discrete cladding modes

DEFF Research Database (Denmark)

Probst, C. B.; Bjarklev, Anders Overgaard; Andreasen, S. B.

1989-01-01

a microbending theory in which coupling between the guided mode and a number of discrete cladding modes is considered. Very good agreement between theory and measurement is achieved. The consequences of the existence of discrete cladding modes with regard to the proper choice of artificial microbending spectrum...

Nonlinear drift tearing mode. Strong mode of excitation and stabilization mechanisms

International Nuclear Information System (INIS)

Galeev, A.A.; Zelenyj, L.M.; Kuznetsova, M.M.

1985-01-01

A nonlinear theory of magnetic disturbance development in collisionless configurations with magnetic field shear is considered. The instability evolution is investigated with account for the dynamics of ions and potential electric fields which determine the mode stabilization. It has been found that the drift tearing mode possesses metastable properties: in a nonlinear mode even the growth of linearly stable disturbances of the finite amplitude is possible

Modeling of a sensitive time-of-flight flash LiDAR system

Science.gov (United States)

Fathipour, V.; Wheaton, S.; Johnson, W. E.; Mohseni, H.

2016-09-01

used for monitoring and profiling structures, range, velocity, vibration, and air turbulence. Remote sensing in the IR region has several advantages over the visible region, including higher transmitter energy while maintaining eye-safety requirements. Electron-injection detectors are a new class of detectors with high internal avalanche-free amplification together with an excess-noise-factor of unity. They have a cutoff wavelength of 1700 nm. Furthermore, they have an extremely low jitter. The detector operates in linear-mode and requires only bias voltage of a few volts. This together with the feedback stabilized gain mechanism, makes formation of large-format high pixel density electron-injection FPAs less challenging compared to other detector technologies such as avalanche photodetectors. These characteristics make electron-injection detectors an ideal choice for flash LiDAR application with mm scale resolution at longer ranges. Based on our experimentally measured device characteristics, a detailed theoretical LiDAR model was developed. In this model we compare the performance of the electron-injection detector with commercially available linear-mode InGaAs APD from (Hamamatsu G8931-20) as well as a p-i-n diode (Hamamatsu 11193 p-i-n). Flash LiDAR images obtained by our model, show the electron-injection detector array (of 100 x 100 element) achieves better resolution with higher signal-to-noise compared with both the InGaAs APD and the p-i-n array (of 100 x 100 element).

Alarm personal dosemeter

International Nuclear Information System (INIS)

Nunomiya, Tomoya; Yamauchi, Hideshi; Shibata, Tetsuo

2007-01-01

Fuji Electric advanced the development of the conventional alarm personal dosemeter (APD) by adopting JIS Z 4312 (2002), which reflects IEC61526 (1998), and by improving the radiation performance characteristics, electromagnetic performance characteristics and mechanical performance characteristics of the APD (acquiring a CE marking). This new dosemeter will target overseas market in the future. The APD is a suitable dosemeter for detecting and monitoring radiation exposure to personnel working in the controlled areas of nuclear facilities, such as nuclear power stations. The APD product line includes 'gamma ray', 'gamma ray + beta ray' and 'gamma ray + neutron' models. (author)

Tacoma mode

International Nuclear Information System (INIS)

Courant, E.D.; Ruth, R.D.; Wang, J.M.

1979-01-01

The name Tacoma refers to the Tacoma Narrows Bridge which collapsed on November 8, 1940 due to massive oscillations caused by high winds. One of the destructive modes was a torsion mode which was excited by transverse wind, a dipole force, and continued until the bridge collapsed. The name is used to refer to a coherent mode of oscillation of a spectrum of oscillators in which the amplitude vs frequency graph contains one node, where the node occurs near the driving frequency and a(ω) is not symmetric about zero. When this result is applied to vertical instabilities in coasting beams, it implies the existence of a coherent skew quadrupole moment, whenever a coherent dipole oscillation exists

Coupled-Mode Theory derivation of the formal equivalence between a three-mode waveguide and a set of three mutually coupled single-mode waveguides

Directory of Open Access Journals (Sweden)

Boucher Yann G.

2017-01-01

Full Text Available The formal identification between a two-mode waveguide and a system of two mutually coupled single-mode waveguides stems from the symmetries of the evolution operator. When the gap tends to zero, the super-modes of the coupled system merge continuously into the modes of the multimode waveguide. For modelling purposes, it is very tempting to extend the analogy to three-mode waveguides (and beyond. But not without some precautions…

L to H-mode Power Threshold and Confinement Characteristics of H-modes in KSTAR

Energy Technology Data Exchange (ETDEWEB)

Kim, H. S.; Na, Y.S., E-mail: ftwalker.hyuns@gmail.com [Seoul National University, Seoul (Korea, Republic of); Ahn, J. W. [Oak Ridge National Laboratory, Oak Ridge (United States); Jeon, Y. M.; Yoon, S. W.; Lee, K. D.; Ko, W. H.; Bae, Y. S.; Kim, W. C.; Kwak, J. G. [National Fusion Research Institute, Daejeon (Korea, Republic of)

2012-09-15

Full text: Since KSTAR has obtained the H-mode in 2010 campaign, H-mode plasmas were routinely obtained with combined heating of NBI with maximum power of 1.5 MW and ECRH with maximum power of {approx} 0.3 MW and {approx} 0.6 MW for 110 GHz and 170 GHz, respectively. The L- to H-mode power threshold and confinement properties of KSTAR H-modes are investigated in this work. Firstly, the L- to H-mode power threshold and the power loss to the seperatrix are calculated by power balance analysis for about collected 400 shots. As a result, a trend of roll-over is observed in the power threshold of KSTAR H-mode compared with the multi-machine power threshold scaling in the low density regime. Dependence of the power threshold on other parameters are also investigated such as the X-point position and shaping parameters like as triangularity and elongation. In addition, the reason of reduction of power threshold in 2011 campaign compared with that in 2010 is addressed. Secondly, the confinement enhancement factors are calculated to evaluate the performance of KSTAR H-modes. The calculated H{sub 89-p} and H{sub 98} (y, 2) represent that the confinement is enhanced in most KSTAR H-mode discharges. Interestingly, even in L-mode phases, confinement is observed to be enhanced against the multi-machine scalings. H{sub exp} factor is newly introduced to evaluate the amount of confinement improvement in the H-mode phase compared with the L-mode phase in a single discharge. H{sub exp} exhibits that the global energy confinement time of the H-mode phase is improved about 1.3 - 2.0 times compared with that of the L-mode phase. Finally, interpretive and predictive numerical simulations are carried out using the ASTRA code for typical KSTAR H-mode discharges. The Weiland model and the GLF23 model are employed for calculating the anomalous contributions of both electron and ion heat transport in predictive simulations. For the H-mode phase, the Weiland model reproduces the experiment

Transition from L mode to high ion temperature mode in CHS heliotron/torsatron plasmas

International Nuclear Information System (INIS)

Ida, K.; Osakabe, M.; Tanaka, K.

2001-01-01

A high ion temperature mode (high T i mode) is observed for neutral beam heated plasmas in the Compact Helical System (CHS) Heliotron/torsatron. The high T i mode plasma is characterized by a high central ion temperature, T i (0), and is associated with a peaked electron density profile produced by neutral beam fueling with low wall recycling. Transition from L mode to high T i mode has been studied in CHS. The central ion temperature in the high T i mode discharges reaches to 1 keV which is 2.5 times higher than that in the L mode discharges. The ion thermal diffusivity is significantly reduced by a factor of more than 2-3 in the high T i mode plasma. The ion loss cone is observed in neutral particle flux in the energy range of 1-6 keV with a narrow range of pitch angle (90±10 degree) in the high T i mode. However, the degradation of ion energy confinement due to this loss cone is negligible. (author)

Mode conversion efficiency to Laguerre-Gaussian OAM modes using spiral phase optics.

Science.gov (United States)

Longman, Andrew; Fedosejevs, Robert

2017-07-24

An analytical model for the conversion efficiency from a TEM 00 mode to an arbitrary Laguerre-Gaussian (LG) mode with null radial index spiral phase optics is presented. We extend this model to include the effects of stepped spiral phase optics, spiral phase optics of non-integer topological charge, and the reduction in conversion efficiency due to broad laser bandwidth. We find that through optimization, an optimal beam waist ratio of the input and output modes exists and is dependent upon the output azimuthal mode number.

Perspective gyrotron with mode converter for co- and counter-rotation operating modes

Energy Technology Data Exchange (ETDEWEB)

Chirkov, A. V.; Kuftin, A. N. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ul' yanov Street, 603950 Nizhny Novgorod (Russian Federation); Denisov, G. G. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ul' yanov Street, 603950 Nizhny Novgorod (Russian Federation); University of Nizhny Novgorod, 23 Prospekt Gagarina, 603950 Nizhny Novgorod (Russian Federation)

2015-06-29

A gyrotron oscillator operating efficiently at modes of both rotations was developed and tested. The gyrotron operation can be switched between two modes: co- and counter rotating ones with respect to electron rotation in a resonance magnetic field. A synthesized mode converter provides output of both waves in the form of two different paraxial wave beams corresponding to direction of the mode rotation. Measured gyrotron power (up to 2 MW), interaction efficiency (34%), and diffraction losses in the mode converter (≈2%) agree well with the design values. The proposed gyrotron scheme alloys principal enhancement in the device parameters—possibility of electronic switching of output wave beam direction and possibility to arrange an effective scheme to provide frequency/phase locking of a gyrotron-oscillator.

Perspective gyrotron with mode converter for co- and counter-rotation operating modes

International Nuclear Information System (INIS)

Chirkov, A. V.; Kuftin, A. N.; Denisov, G. G.

2015-01-01

A gyrotron oscillator operating efficiently at modes of both rotations was developed and tested. The gyrotron operation can be switched between two modes: co- and counter rotating ones with respect to electron rotation in a resonance magnetic field. A synthesized mode converter provides output of both waves in the form of two different paraxial wave beams corresponding to direction of the mode rotation. Measured gyrotron power (up to 2 MW), interaction efficiency (34%), and diffraction losses in the mode converter (≈2%) agree well with the design values. The proposed gyrotron scheme alloys principal enhancement in the device parameters—possibility of electronic switching of output wave beam direction and possibility to arrange an effective scheme to provide frequency/phase locking of a gyrotron-oscillator

Clinical characteristics of self-mutilating behavior in Turkish male subjects with antisocial personality disorder: relationship to psychopathy.

Science.gov (United States)

Alpay Ates, M; Algul, Ayhan; Semiz, Umit B; Gecici, Omer; Basoglu, Cengiz; Ebrinc, Servet; Cetin, Mesut

2011-05-01

The aims of this study were to determine the characteristics of self-mutilation (SM) and examine the relationship between SM and psychopathy in male subjects with antisocial personality disorder (APD). APD diagnosis was established by the Structured Clinical Interview for DSM-III-R Axis II Disorders. Subjects (N = 116) were assessed using the Psychopathy Checklist-Revised and a semi-structured self-mutilation questionnaire form. In males with APD, the percentages of psychopathy and SM were 48.3% (N =56) and 96.6% (N = 112), respectively. There were positive correlations between severity of psychopathy and severity, number, and frequency of SM. Considerably high rates of SM and psychopathy were found in Turkish males with APD. The features of SM were associated with comorbidity of psychopathy. These results showed the importance of exploring the self-injurious behavior and psychopathy when diagnosed with APD.

White matter abnormalities in young males with antisocial personality disorder Evidence from voxel-based morphometry-diffeomorphic anatomical registration using exponentiated lie algebra analysis

Institute of Scientific and Technical Information of China (English)

Daxing Wu; Ying Zhao; Jian Liao; Huifang Yin; Wei Wang

2011-01-01

Voxel-based morphometry-diffeomorphic anatomical registration using exponentiated lie algebra analysis was used to investigate the structural characteristics of white matter in young males with antisocial personality disorder (APD) and healthy controls without APD. The results revealed that APD subjects, relative to healthy subjects, exhibited increased white matter volume in the bilateral prefrontal lobe, right insula, precentral gyrus, bilateral superior temporal gyrus, right postcentral gyrus, right inferior parietal lobule, right precuneus, right middle occipital lobe, right parahippocampal gyrus and bilateral cingulate, and decreased volume in the middle temporal cortex and right cerebellum. The white matter volume in the medial frontal gyrus was significantly correlated with antisocial type scores on the Personality Diagnostic Questionnaire in APD subjects. These experimental findings indicate that white matter abnormalities in several brain areas may contribute to antisocial behaviors in APD subjects.

Measuring the absolute disintegration rate of a radioactive gas with a moveable endplate discharge counter (MEP) and theoretical calculation of wall effect

International Nuclear Information System (INIS)

Jaffey, A.H.; Gray, J.; Bentley, W.C.; Lerner, J.L.

1987-09-01

A precision built moveable endplate Geiger-Mueller counter was used to measure the absolute disintegration rate of a beta-emitting radioactive gas. A Geiger-Mueller counter used for measuring gaseous radioactivity has 85 Kr (beta energy, 0.67 MeV). The wall effect calculation is readily extendable to other beta energies

Robust fiber optic flexure sensor exploiting mode coupling in few-mode fiber

Science.gov (United States)

Nelsen, Bryan; Rudek, Florian; Taudt, Christopher; Baselt, Tobias; Hartmann, Peter

2015-05-01

Few-mode fiber (FMF) has become very popular for use in multiplexing telecommunications data over fiber optics. The simplicity of producing FMF and the relative robustness of the optical modes, coupled with the simplicity of reading out the information make this fiber a natural choice for communications. However, little work has been done to take advantage of this type of fiber for sensors. Here, we demonstrate the feasibility of using FMF properties as a mechanism for detecting flexure by exploiting mode coupling between modes when the cylindrical symmetry of the fiber is perturbed. The theoretical calculations shown here are used to understand the coupling between the lowest order linearly polarized mode (LP01) and the next higher mode (LP11x or LP11y) under the action of bending. Twisting is also evaluated as a means to detect flexure and was determined to be the most reliable and effective method when observing the LP21 mode. Experimental results of twisted fiber and observations of the LP21 mode are presented here. These types of fiber flexure sensors are practical in high voltage, high magnetic field, or high temperature medical or industrial environments where typical electronic flexure sensors would normally fail. Other types of flexure measurement systems that utilize fiber, such as Rayleigh back-scattering [1], are complicated and expensive and often provide a higher-than necessary sensitivity for the task at hand.

Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

Energy Technology Data Exchange (ETDEWEB)

Nishikido, Fumihiko, E-mail: funis@nirs.go.j [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Inadama, Naoko [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Oda, Ichiro [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kitamura, Keishi [Shimadzu Corporation, Nishinokyo Kuwabaracho 1 Nakagyo-ku, Kyoto-shi, Kyoto 604-8511 (Japan); Murayama, Hideo [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2010-09-21

Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6x6x4 array of 1.46x1.46 mm{sup 2}x4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

Four-layer depth-of-interaction PET detector for high resolution PET using a multi-pixel S8550 avalanche photodiode

International Nuclear Information System (INIS)

Nishikido, Fumihiko; Inadama, Naoko; Oda, Ichiro; Shibuya, Kengo; Yoshida, Eiji; Yamaya, Taiga; Kitamura, Keishi; Murayama, Hideo

2010-01-01

Avalanche photodiodes (APDs) are being used as photodetectors in positron emission tomography (PET) because they have many advantages over photomultipliers (PMTs) typically used in PET detectors. We have developed a PET detector that consists of a multi-pixel APD and a 6x6x4 array of 1.46x1.46 mm 2 x4.5 m LYSO crystals for a small animal PET scanner. The detector can identify four-layer depth of interaction (DOI) with a position-sensitive APD coupled to the backside of a crystal array by just an optimized reflector arrangement. Since scintillation lights are shared among many pixels by the method, weaker signals in APD pixels far from the interacting crystals are affected by noise. To evaluate the performance of the four-layer DOI detector with the APD and the influence of electrical noise on our method, we constructed a prototype DOI detector and tested its performance. We found, except for crystal elements on the edge of the crystal array, all crystal elements could be identified from the 2D position histogram. An energy resolution of 16.9% was obtained for the whole crystal array of the APD detector. The results of noise dependence of detector performances indicated that the DOI detector using the APD could achieve sufficient performance even when using application-specific integrated circuits.

Evaluation of phase sensitive detection method and Si avalanche photodiode for radiation thermometry

International Nuclear Information System (INIS)

Hobbs, M J; Tan, C H; Willmott, J R

2013-01-01

We report the evaluation of Si avalanche photodiodes (APDs) for use in radiation thermometry as an alternative to Si photodiodes. We compared their performance when operated under phase sensitive detection (PSD), where the signal is modulated, and direct detection (DD) methods. A Si APD was compared with a Si photodiode with reference black body temperatures of 275 to 600°C, in terms of the mean output voltage and signal-to-noise ratio (SNR), measured at different APD gain values. We found that using both PSD and DD methods, the high internal gain of the Si APD achieved a lower minimum detection temperature in order to satisfy a specific minimum output voltage of the detector-preamplifier combination employed. The use of PSD over DD for the Si APD allowed for improved performance of the thermometer, with a lower minimum measurable temperature, as well as improvement in the SNR. For instance we found that at 350°C, the Si APD biased at 150 V using PSD can provide ∼ 88 times enhancement in the system SNR over that of a Si photodiode using DD. A corresponding temperature error of ±0.05°C was achieved using the APD with PSD compared to an error of ±2.75°C measured using the Si photodiode with DD.

Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern

DEFF Research Database (Denmark)

Schunk, Gerhard; Fuerst, Josef U.; Förtsch, Michael

2014-01-01

Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMR...

Approaches to single photon detection

International Nuclear Information System (INIS)

Thew, R.T.; Curtz, N.; Eraerds, P.; Walenta, N.; Gautier, J.-D.; Koller, E.; Zhang, J.; Gisin, N.; Zbinden, H.

2009-01-01

We present recent results on our development of single photon detectors, including: gated and free-running InGaAs/InP avalanche photodiodes (APDs); hybrid detection systems based on sum-frequency generation (SFG) and Si APDs-SFG-Si APDs; and SSPDs (superconducting single photon detectors), for telecom wavelengths; as well as SiPM (Silicon photomultiplier) detectors operating in the visible regime.

Large area avalanche MRS-photodiodes for nuclear spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Ermalitski, F A; Zalesski, V B

1996-12-31

Problems of application of avalanche photodiodes (APD) in readout systems of nuclear spectrometers are considered. APD`s with a large sensitive area of a diameter 1-5 mm and a high multiplication coefficient 200-1000 are created. MPS-photodiodes provide for the energy resolution 80% at temperature 231 K for detecting gamma-quanta with energy 662 keV. 4 refs.

Comparison of detectability in step-and-shoot mode and continuous mode digital tomosynthesis systems

Science.gov (United States)

Lee, Changwoo; Han, Minah; Baek, Jongduk

2017-03-01

Digital tomosynthesis system has been widely used in chest, dental, and breast imaging. Since the digital tomosynthesis system provides volumetric images from multiple projection data, structural noise inherent in X-ray radiograph can be reduced, and thus signal detection performance is improved. Currently, tomosynthesis system uses two data acquisition modes: step-and-shoot mode and continuous mode. Several studies have been conducted to compare the system performance of two acquisition modes with respect to spatial resolution and contrast. In this work, we focus on signal detectability in step-and-shoot mode and continuous mode. For evaluation, uniform background is considered, and eight spherical objects with diameters of 0.5, 0.8, 1, 2, 3, 5, 8, 10 mm are used as signals. Projection data with and without spherical objects are acquired in step-and-shoot mode and continuous mode, respectively, and quantum noise are added. Then, noisy projection data are reconstructed by FDK algorithm. To compare the detection performance of two acquisition modes, we calculate task signal-to-noise ratio (SNR) of channelized Hotelling observer with Laguerre-Gauss channels for each spherical object. While the task-SNR values of two acquisition modes are similar for spherical objects larger than 1 mm diameter, step-and-shoot mode yields higher detectability for small signal sizes. The main reason of this behavior is that small signal is more affected by X-ray tube motion blur than large signal. Our results indicate that it is beneficial to use step-and-shoot data acquisition mode to improve the detectability of small signals (i.e., less than 1 mm diameter) in digital tomosynthesis systems.

Normal modes of Bardeen discs

International Nuclear Information System (INIS)

Verdaguer, E.

1983-01-01

The short wavelength normal modes of self-gravitating rotating polytropic discs in the Bardeen approximation are studied. The discs' oscillations can be seen in terms of two types of modes: the p-modes whose driving forces are pressure forces and the r-modes driven by Coriolis forces. As a consequence of differential rotation coupling between the two takes place and some mixed modes appear, their properties can be studied under the assumption of weak coupling and it is seen that they avoid the crossing of the p- and r-modes. The short wavelength analysis provides a basis for the classification of the modes, which can be made by using the properties of their phase diagrams. The classification is applied to the large wavelength modes of differentially rotating discs with strong coupling and to a uniformly rotating sequence with no coupling, which have been calculated in previous papers. Many of the physical properties and qualitative features of these modes are revealed by the analysis. (author)

Tacoma mode

International Nuclear Information System (INIS)

Courant, E.D.; Ruth, R.D.; Wang, J.M.

1979-01-01

The name Tacoma refers to the Tacoma Narrows Bridge which collapsed on November 8, 1940 due to massive oscillations caused by high winds. One of the destructive modes was a torsion mode which was excited by transverse wind, a dipole force, and continued until the bridge collapsed. The name is used to refer to a coherent mode of oscillation of a spectrum of oscillators in which the amplitude vs frequency graph contains one node, where the node occurs near the driving frequency and a ω is not symmetric about zero. When this result is applied to vertical instabilities in coasting beams, it implies the existence of a coherent skew quadrupole moment, Q/sub xy/, whenever a coherent dipole oscillation exists

Pad-mode-induced instantaneous mode instability for simple models of brake systems

Science.gov (United States)

Oberst, S.; Lai, J. C. S.

2015-10-01

Automotive disc brake squeal is fugitive, transient and remains difficult to predict. In particular, instantaneous mode squeal observed experimentally does not seem to be associated with mode coupling and its mechanism is not clear. The effects of contact pressures, friction coefficients as well as material properties (pressure and temperature dependency and anisotropy) for brake squeal propensity have not been systematically explored. By analysing a finite element model of an isotropic pad sliding on a plate similar to that of a previously reported experimental study, pad modes have been identified and found to be stable using conventional complex eigenvalue analysis. However, by subjecting the model to contact pressure harmonic excitation for a range of pressures and friction coefficients, a forced response analysis reveals that the dissipated energy for pad modes is negative and becomes more negative with increasing contact pressures and friction coefficients, indicating the potential for instabilities. The frequency of the pad mode in the sliding direction is within the range of squeal frequencies observed experimentally. Nonlinear time series analysis of the vibration velocity also confirms the evolution of instabilities induced by pad modes as the friction coefficient increases. By extending this analysis to a more realistic but simple brake model in the form of a pad-on-disc system, in-plane pad-modes, which a complex eigenvalue analysis predicts to be stable, have also been identified by negative dissipated energy for both isotropic and anisotropic pad material properties. The influence of contact pressures on potential instabilities has been found to be more dominant than changes in material properties owing to changes in pressure or temperature. Results here suggest that instantaneous mode squeal is likely caused by in-plane pad-mode instabilities.

Education Is His Business.

Science.gov (United States)

Natale, Jo Anna

1993-01-01

Superintendent Philip Geiger recently risked unpopularity in one suburban New Jersey district by privatizing the bus service and using savings for a truckload of classroom computers. Armed with an MBA and a passion for zero-based budgeting, Geiger has also braved union displeasure by advocating faculty workload increases in students' interest. An…

The Integrated Mode Management Interface

Science.gov (United States)

Hutchins, Edwin

1996-01-01

Mode management is the processes of understanding the character and consequences of autoflight modes, planning and selecting the engagement, disengagement and transitions between modes, and anticipating automatic mode transitions made by the autoflight system itself. The state of the art is represented by the latest designs produced by each of the major airframe manufacturers, the Boeing 747-400, the Boeing 777, the McDonnell Douglas MD-11, and the Airbus A320/A340 family of airplanes. In these airplanes autoflight modes are selected by manipulating switches on the control panel. The state of the autoflight system is displayed on the flight mode annunciators. The integrated mode management interface (IMMI) is a graphical interface to autoflight mode management systems for aircraft equipped with flight management computer systems (FMCS). The interface consists of a vertical mode manager and a lateral mode manager. Autoflight modes are depicted by icons on a graphical display. Mode selection is accomplished by touching (or mousing) the appropriate icon. The IMMI provides flight crews with an integrated interface to autoflight systems for aircraft equipped with flight management computer systems (FMCS). The current version is modeled on the Boeing glass-cockpit airplanes (747-400, 757/767). It runs on the SGI Indigo workstation. A working prototype of this graphics-based crew interface to the autoflight mode management tasks of glass cockpit airplanes has been installed in the Advanced Concepts Flight Simulator of the CSSRF of NASA Ames Research Center. This IMMI replaces the devices in FMCS equipped airplanes currently known as mode control panel (Boeing), flight guidance control panel (McDonnell Douglas), and flight control unit (Airbus). It also augments the functions of the flight mode annunciators. All glass cockpit airplanes are sufficiently similar that the IMMI could be tailored to the mode management system of any modern cockpit. The IMMI does not replace the

Poloidal rotation and the evolution of H-mode and VH-mode profiles

International Nuclear Information System (INIS)

Hinton, F.L.; Staebler, G.M.; Kim, Y.B.

1993-12-01

The physics which determines poloidal rotation, and its role in the development of profiles during H- and VH-modes, is discussed. A simple phenomenological transport model, which incorporates the rvec E x rvec B flow shear suppression of turbulence, is shown to predict profile evolution similar to that observed experimentally during H-mode and VH-mode

Design and numerical optimization of a mode multiplexer based on few-mode fiber couplers

International Nuclear Information System (INIS)

Xie, Yiwei; Fu, Songnian; Liu, Hai; Zhang, Hailiang; Tang, Ming; Liu, Deming; Shum, P

2013-01-01

Mode division multiplexing (MDM) transmission based on few-mode fibers (FMFs) appears to be an alternative solution for overcoming the capacity limit of single-mode fibers (SMFs). A FMF coupler-based mode division multiplexer/demultiplexer (MMUX/DeMMUX) is proposed and theoretically investigated after the fabricated FMF is characterized. MMUXs/DeMMUXs with a mode contrast ratio (MCR) of more than 20 dB can be obtained for two-mode multiplexing and three-mode multiplexing over a wavelength span of 60 and 10 nm, respectively. We numerically verify the proposed MMUX/DeMMUX which has the advantages of high MCR, easy fabrication and maintenance, and low wavelength dependence. (paper)

[Short-term sentence memory in children with auditory processing disorders].

Science.gov (United States)

Kiese-Himmel, C

2010-05-01

To compare sentence repetition performance of different groups of children with Auditory Processing Disorders (APD) and to examine the relationship between age or respectively nonverbal intelligence and sentence recall. Nonverbal intelligence was measured with the COLOURED MATRICES, in addition the children completed a standardized test of SENTENCE REPETITION (SR) which requires to repeat spoken sentences (subtest of the HEIDELBERGER SPRACHENTWICKLUNGSTEST). Three clinical groups (n=49 with monosymptomatic APD; n=29 with APD+developmental language impairment; n=14 with APD+developmental dyslexia); two control groups (n=13 typically developing peers without any clinical developmental disorder; n=10 children with slight reduced nonverbal intelligence). The analysis showed a significant group effect (p=0.0007). The best performance was achieved by the normal controls (T-score 52.9; SD 6.4; Min 42; Max 59) followed by children with monosymptomatic APD (43.2; SD 9.2), children with the co-morbid-conditions APD+developmental dyslexia (43.1; SD 10.3), and APD+developmental language impairment (39.4; SD 9.4). The clinical control group presented the lowest performance, on average (38.6; SD 9.6). Accordingly, language-impaired children and children with slight reductions in intelligence could poorly use their grammatical knowledge for SR. A statistically significant improvement in SR was verified with the increase of age with the exception of children belonging to the small group with lowered intelligence. This group comprised the oldest children. Nonverbal intelligence correlated positively with SR only in children with below average-range intelligence (0.62; p=0.054). The absence of APD, SLI as well as the presence of normal intelligence facilitated the use of phonological information for SR.

Mode coupling trigger of neoclassical magnetohydrodynamic tearing modes in tokamaks

International Nuclear Information System (INIS)

Gianakon, T.A.; Hegna, C.C.; Callen, J.D.

1997-05-01

Numerical studies of the nonlinear evolution of coupled magnetohydrodynamic - type tearing modes in three-dimensional toroidal geometry with neoclassical effects are presented. The inclusion of neoclassical physics introduces an additional free-energy source for the nonlinear formation of magnetic islands through the effects of a bootstrap current in Ohm's law. The neoclassical tearing mode is demonstrated to be destabilized in plasmas which are otherwise Δ' stable, albeit once a threshold island width is exceeded. A possible mechanism for exceeding or eliminating this threshold condition is demonstrated based on mode coupling due to toroidicity with a pre-existing instability at the q = 1 surface

Inhibitory neuron and hippocampal circuit dysfunction in an aged mouse model of Alzheimer's disease.

Directory of Open Access Journals (Sweden)

Anupam Hazra

Full Text Available In Alzheimer's disease (AD, a decline in explicit memory is one of the earliest signs of disease and is associated with hippocampal dysfunction. Amyloid protein exerts a disruptive impact on neuronal function, but the specific effects on hippocampal network activity are not well known. In this study, fast voltage-sensitive dye imaging and extracellular and whole-cell electrophysiology were used on entorhinal cortical-hippocampal slice preparations to characterize hippocampal network activity in 12-16 month old female APPswe/PSEN1DeltaE9 (APdE9 mice mice. Aged APdE9 mice exhibited profound disruptions in dentate gyrus circuit activation. High frequency stimulation of the perforant pathway in the dentate gyrus (DG area of APdE9 mouse tissue evoked abnormally large field potential responses corresponding to the wider neural activation maps. Whole-cell patch clamp recordings of the identified inhibitory interneurons in the molecular layer of DG revealed that they fail to reliably fire action potentials. Taken together, abnormal DG excitability and an inhibitory neuron failure to generate action potentials are suggested to be important contributors to the underlying cellular mechanisms of early-stage Alzheimer's disease pathophysiology.

Ultra-small platinum and gold nanoparticles by arc plasma deposition

International Nuclear Information System (INIS)

Kim, Sang Hoon; Jeong, Young Eun; Ha, Heonphil; Byun, Ji Young; Kim, Young Dok

2014-01-01

Highlights: • Ultra-small (<2 nm) and bigger platinum and gold nanoparticles were produced by arc plasma deposition (APD). • Size and coverage of deposited nanoparticles were easily controlled with APD parameters. • Crystalline structures of deposited nanoparticles emerged only when the particle size was bigger than ∼2 nm. - Abstract: Ultra-small (<2 nm) nanoparticles of platinum and gold were produced by arc plasma deposition (APD) in a systematic way and the deposition behavior was studied. Nanoparticles were deposited on two dimensional amorphous carbon and amorphous titania thin films and characterized by transmission electron microscopy (TEM). Deposition behavior of nanoparticles by APD was studied with discharge voltage (V), discharge condenser capacitance (C), and the number of plasma pulse shots (n) as controllable parameters. The average size of intrinsic nanoparticles generated by APD process was as small as 0.9 nm and deposited nanoparticles began to have crystal structures from the particle size of about 2 nm. V was the most sensitive parameter to control the size and coverage of generated nanoparticles compared to C and n. Size of APD deposited nanoparticles was also influenced by the nature of evaporating materials and substrates

Self-rated health assessed by web versus mail modes in a mixed mode survey: the digital divide effect and the genuine survey mode effect.

Science.gov (United States)

Shim, Jae-Mahn; Shin, Eunjung; Johnson, Timothy P

2013-09-01

To investigate differences in self-rated health (SRH) between web and mail questionnaires in a mixed mode survey and to provide a model that explains those differences. A total of 15,200 mail respondents and 17,829 web respondents from the 2008 US National Health Survey conducted by the Gallup Panel. Respondents were recruited using random digit dialing and assigned to one of the two survey modes (web or mail). Respondents with household Internet connection and frequent Internet usage were invited to complete the survey through the web mode. Respondents who had no Internet connection or who used the Internet infrequently were invited to the mail mode. Thus, respondents with better Internet access used the web mode. Respondents completed a questionnaire that asked about SRH status, objective health conditions, health behaviors, and other socioeconomic variables. Statistical associations were analyzed with ordered Logit and negative binomial models. Web respondents reported better SRH than mail respondents. This difference is in part reflective of variability in objective health status between these two groups, and in part attributable to the effects of survey mode. These results maintained with age controlled. The alignment between survey mode selection, Internet access, and health disparities, as well as genuine survey mode characteristics, leads to web-mail differences in SRH. Unless the digital divide and its influences on survey mode selection are resolved and differential genuine mode effects are fully comprehended, we recommend that both modes be simultaneously used on a complementary basis.

Characteristics of edge localized mode in JFT-2M H-mode

International Nuclear Information System (INIS)

Matsumoto, Hiroshi; Funahashi, Akimasa; Goldston, R.J.

1989-03-01

Characteristics of edge localized mode (ELM/ERP) during H-mode plasma of JFT-2M were investigated. It was found that ELM/ERP is mainly a density fluctuation phenomena in the edge, and electron temperature in the edge except just near the separatrix is not very much perturbed. Several experimental conditions to controll ELM/ERP are, plasma density, plasma ion species, heating power, and plasma current ramping. ELM/ERPs found in low density deuterium discharge are suppressed by raising the density. ELM/ERPs are pronounced in hydrogen plasma compared with deuterium plasma. ELM/ERPs seen in hydrogen plasma or in near marginal H-mode conditions are suppressed by increasing the heating power. ELM/ERPs are found to be suppressed by plasma current ramp down, whereas they are enhanced by current ramp up. MHD aspect of ELM/ERP was investigated. No clear MHD features of ELM/ERP were found. However, reversal of mode rotation seen imediately after ELM/ERP suggests the temporal return to L-mode during the ELM/ERP event. (author)

All-fiber optical mode switching based on cascaded mode selective couplers for short-reach MDM networks

Science.gov (United States)

Ren, Fang; Li, Juhao; Wu, Zhongying; Yu, Jinyi; Mo, Qi; Wang, Jianping; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

2017-04-01

We propose and experimentally demonstrate an all-fiber optical mode switching structure supporting independent switching, exchanging, adding, and dropping functionalities in which each mode can be switched individually. The mode switching structure consists of cascaded mode selective couplers (MSCs) capable of exciting and selecting specific higher order modes in few-mode fibers with high efficiency and one multiport optical switch routing the independent spatial modes to their destinations. The data carried on three different spatial modes can be switched, exchanged, added, and dropped through this all-fiber structure. For this experimental demonstration, optical on-off-keying (OOK) signals at 10-Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. The mode switch exhibits power penalties of less than 3.1 dB after through operation, less than 2.7 dB after exchange operation, less than 2.8 dB after switching operation, and less than 1.6 dB after mode adding and dropping operations at the bit-error rate (BER) of 10-3, while all three channels carried on three spatial modes are simultaneously routed. The proposed structure, compatible with current optical switching networks based on single-mode fibers, can potentially be used to expand the switching scalability in advanced and flexible short-reach mode-division multiplexing-based networks.

[Effects of dauricine on action potentials and slow inward currents of guinea pig ventricular papillary muscles].

Science.gov (United States)

Li, S N; Zhang, K Y

1992-11-01

Effects of dauricine (Dau) on the action potentials (AP), the slow action potentials (SAP), and the slow inward currents (Isi) of guinea pig ventricular papillary muscles were observed by means of intracellular microelectrode and single sucrose gap voltage clamp technique. In the early stage, Dau shortened action potential duration 100 (APD100) and effective refractory period (ERP) (ERP/APD ERP, and APD20, significantly decreased action potential amplitude (APA), maximum velocity (Vmax), and overshot (OS) (ERP/APD > 1; P SAP induced by isoprenaline (P < 0.01), and remarkably inhibited Isi (P < 0.01). The results suggested that Dau exerted an inhibitory effect on Na+, Ca2+, and K+ channels.

Discrimination Voltage and Overdrive Bias Dependent Performance Evaluation of Passively Quenched SiC Single-Photon-Counting Avalanche Photodiodes

International Nuclear Information System (INIS)

Liu Fei; Yang Sen; Zhou Dong; Lu Hai; Zhang Rong; Zheng You-Dou

2015-01-01

In many critical civil and emerging military applications, low-level UV detection, sometimes at single photon level, is highly desired. In this work, a mesa-type 4H-SiC UV avalanche photodiode (APD) is designed and fabricated, which exhibits low leakage current and high avalanche gain. When studied by using a passive quenching circuit, the APD exhibits self-quenching characteristics due to its high differential resistance in the avalanche region. The single photon detection efficiency and dark count rate of the APD are evaluated as functions of discrimination voltage and over-drive voltage. The optimized operation conditions of the single photon counting APD are discussed. (paper)

Single-mode regime in large-mode-area rare-earth-doped rod-type PCFs

DEFF Research Database (Denmark)

Poli, F.; Cucinotta, A.; Passaro, D.

2009-01-01

In this paper, large-mode-area, double-cladding, rare-earth-doped photonic crystal fibers are investigated in order to understand how the refractive index distribution and the mode competition given by the amplification can assure single-mode propagation. Fibers with different core diameters, i...

Cross-correlated imaging of single-mode photonic crystal rod fiber with distributed mode filtering

DEFF Research Database (Denmark)

Laurila, Marko; Barankov, Roman; Jørgensen, Mette Marie

2013-01-01

Photonic crystal bandgap fibers employing distributed mode filtering design provide near diffraction-limited light outputs, a critical property of fiber-based high-power lasers. Microstructure of the fibers is tailored to achieve single-mode operation at specific wavelength by resonant mode...... identify regimes of resonant coupling between higher-order core modes and cladding band. We demonstrate a passive fiber design in which the higher-order modal content inside the single-mode guiding regime is suppressed by at least 20 dB even for significantly misaligned input-coupling configurations....

Amygdala Reactivity and Negative Emotionality: Divergent Correlates of Antisocial Personality and Psychopathy Traits in a Community Sample

OpenAIRE

Hyde, Luke W.; Byrd, Amy L.; Votruba-Drzal, Elizabeth; Hariri, Ahmad R.; Manuck, Stephen B.

2014-01-01

Previous studies have emphasized that antisocial personality disorder (APD) and psychopathy overlap highly but differ critically in several features, notably negative emotionality (NEM) and possibly amygdala reactivity to social signals of threat and distress. Here we examined whether dimensions of psychopathy and APD correlate differentially with NEM and amygdala reactivity to emotional faces. Testing these relationships among healthy individuals, dimensions of psychopathy and APD were gener...

Performance of the latest MPPCs with reduced dark counts and improved photon detection efficiency

International Nuclear Information System (INIS)

Tsujikawa, T.; Funamoto, H.; Kataoka, J.; Fujita, T.; Nishiyama, T.; Kurei, Y.; Sato, K.; Yamamura, K.; Nakamura, S.

2014-01-01

We have tested the performance of two types of the latest Multi-Pixel Photon Counters (MPPCs; measuring 3×3 mm 2 in size) developed by Hamamatsu Photonics K.K. The new S12572-050C is a successor to the S10362-33-050C (i.e., conventional 3×3-mm 2 pixel MPPC of 50 μm pitch), comprises 3600 Geiger mode avalanche photodiodes (APDs), and also features high gain (up to 1.25×10 6 ), a low dark count (up to 10 6 cps), and improved photon detection efficiency (PDE) by up to 30%. The S12572-015C is a new type of fine-pitch (15 μm) MPPC featuring a wide dynamic range and fast timing response. This paper first presents the detailed performance of these latest MPPCs as photon counting devices. It then describes our fabrication of a prototype detector consisting of a MPPC optically coupled with a Ce:GAGG scintillator. We obtained average FWHM energy resolutions of 7.3% (15 μm) and 6.7% (new-50 μm), as compared to 6.9% (old-50 μm) for 662-keV gamma rays from the 137 Cs source, as measured at 20 °C. Moreover, the number of fired pixels for 662-keV gamma rays increased by 30% for the new-50 μm (as compared to the old-50 μm). We confirmed that the low energy threshold improved from 10 keV to 4 keV, when using the latest MPPC device (new-50 μm). We also confirmed that the timing resolution of the new MPPC is 50 ps or even better, as compared to 89 ps of the old MPPC. The results thus confirm that these new types of MPPCs are promising for various applications as scintillation detectors. - Highlights: • We tested the performance of the latest MPPC. • We confirmed that the new MPPC is superior to the old MPPC. • We plan to apply the new MPPC for a next-generation PET and a handy Compton camera

Performance of the latest MPPCs with reduced dark counts and improved photon detection efficiency

Energy Technology Data Exchange (ETDEWEB)

Tsujikawa, T., E-mail: takayuki-t.w@asagi.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Funamoto, H.; Kataoka, J.; Fujita, T.; Nishiyama, T.; Kurei, Y. [Research Institute for Science and Engineering, Waseda University, 3-4-1, Ohkubo, Shinjuku, Tokyo (Japan); Sato, K.; Yamamura, K.; Nakamura, S. [Solid State Division, Hamamatsu Photonics K. K., 1126-1, Ichino-cho, Hamamatsu, Shizuoka (Japan)

2014-11-21

We have tested the performance of two types of the latest Multi-Pixel Photon Counters (MPPCs; measuring 3×3 mm{sup 2} in size) developed by Hamamatsu Photonics K.K. The new S12572-050C is a successor to the S10362-33-050C (i.e., conventional 3×3-mm{sup 2} pixel MPPC of 50 μm pitch), comprises 3600 Geiger mode avalanche photodiodes (APDs), and also features high gain (up to 1.25×10{sup 6}), a low dark count (up to 10{sup 6} cps), and improved photon detection efficiency (PDE) by up to 30%. The S12572-015C is a new type of fine-pitch (15 μm) MPPC featuring a wide dynamic range and fast timing response. This paper first presents the detailed performance of these latest MPPCs as photon counting devices. It then describes our fabrication of a prototype detector consisting of a MPPC optically coupled with a Ce:GAGG scintillator. We obtained average FWHM energy resolutions of 7.3% (15 μm) and 6.7% (new-50 μm), as compared to 6.9% (old-50 μm) for 662-keV gamma rays from the {sup 137}Cs source, as measured at 20 °C. Moreover, the number of fired pixels for 662-keV gamma rays increased by 30% for the new-50 μm (as compared to the old-50 μm). We confirmed that the low energy threshold improved from 10 keV to 4 keV, when using the latest MPPC device (new-50 μm). We also confirmed that the timing resolution of the new MPPC is 50 ps or even better, as compared to 89 ps of the old MPPC. The results thus confirm that these new types of MPPCs are promising for various applications as scintillation detectors. - Highlights: • We tested the performance of the latest MPPC. • We confirmed that the new MPPC is superior to the old MPPC. • We plan to apply the new MPPC for a next-generation PET and a handy Compton camera.

Diagnostic accuracy of combined FP-CIT, IBZM, and MIBG scintigraphy in the differential diagnosis of degenerative parkinsonism: a multidimensional statistical approach.

Science.gov (United States)

Südmeyer, Martin; Antke, Christina; Zizek, Tanja; Beu, Markus; Nikolaus, Susanne; Wojtecki, Lars; Schnitzler, Alfons; Müller, Hans-Wilhelm

2011-05-01

In vivo molecular imaging of pre- and postsynaptic nigrostriatal neuronal degeneration and sympathetic cardiac innervation with SPECT is used to distinguish idiopathic Parkinson disease (PD) from atypical parkinsonian disorder (APD). However, the diagnostic accuracy of these imaging approaches as stand-alone procedures is often unsatisfying. The aim of this study was therefore to evaluate to which extent diagnostic accuracy can be increased by their combined use together with a multidimensional statistical algorithm. The SPECT radiotracers (123)I-(S)-2-hydroxy-3-iodo-6-methoxy-N-[1-ethyl-2-pyrrodinyl)-methyl]benzamide (IBZM), (123)I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)nortropan (FP-CIT), and meta-(123)I-iodobenzylguanidine (MIBG) were used to assess striatal postsynaptic D(2) receptor binding, striatal presynaptic dopamine transporter binding, and myocardial adrenergic innervation, respectively. Thirty-one PD and 17 APD patients were prospectively investigated. PD and APD diagnoses were established using consensus criteria and reevaluated after 37.4 ± 12.4 and 26 ± 11.6 mo in PD and APD, respectively. Test accuracy (TA) for PD-APD differentiation was computed for all logical (Boolean) combinations of imaging modalities by receiver-operating-characteristic analysis--that is, after multidimensional optimization of cutoff values. Analysis showed moderate TA for PD-APD differentiation using each molecular approach alone (IBZM, 79%; MIBG, 73%; and FP-CIT, 73%). For combined use, the highest TA resulted under the assumption that at least 2 of the 3 biologic markers had to be positive for APD using the following cutoff values: 1.46 or less for IBZM, less than 2.10 for FP-CIT, and greater than 1.43 for MIBG. This algorithm distinguished APD from PD with a sensitivity of 94%, specificity of 94% (TA, 94%), positive predictive value of 89%, and negative predictive value of 97%. Results suggest that the multidimensional combination of FP-CIT, IBZM, and MIBG

Is decreased diameter of renal pelvis in prone position an indicator of successful pyeloplasty?

International Nuclear Information System (INIS)

Sharma, Gyanendra; Sharma, Anshu; Leung, Vivian Yee-Fong; Chu, Winnie Chiu-Wing

2016-01-01

To evaluate patients who had undergone pyeloplasty for pelviureteric junction obstruction, by measuring the anteroposterior diameter (APD) of the renal pelvis in supine and prone positions, and determine whether a decrease in APD in prone position can exclude obstruction in dilated renal system. From January 2012 to December 2013, patients who had undergone pyeloplasty were evaluated by ultrasound in two centers. The difference of APD of the renal pelvis in supine and prone positions was obtained. Correlation was made with the pre- and post-pyeloplasty renal function by radionuclide renogram. There were 42 patients (31 males, 11 females; age range 5 months to 18 years). Residual hydronephrosis was detected in 41 patients of whom 35 patients (85%) showed decrease in APD by >10% in prone position. These patients and the one without hydronephrosis showed either no deterioration or improvement in renal function. Six patients (15%) showed either no change or increase in APD in prone position. Three patients (7.5%) were confirmed to have decrease in renal function indicating obstruction. Three patients (7.5%) showed no deterioration of renal function, but sluggish drainage on radionuclide renogram. Demonstration of decreased APD of renal pelvis in prone position by ultrasound is useful to differentiate obstructed from non-obstructed dilated renal system, and it correctly identified 85% candidates with successful pyeloplasty. In patients with no decrease or increase in APD at prone position, further follow-up is recommended to rule out obstruction

Failure mode and effects analysis: an empirical comparison of failure mode scoring procedures.

Science.gov (United States)

Ashley, Laura; Armitage, Gerry

2010-12-01

To empirically compare 2 different commonly used failure mode and effects analysis (FMEA) scoring procedures with respect to their resultant failure mode scores and prioritization: a mathematical procedure, where scores are assigned independently by FMEA team members and averaged, and a consensus procedure, where scores are agreed on by the FMEA team via discussion. A multidisciplinary team undertook a Healthcare FMEA of chemotherapy administration. This included mapping the chemotherapy process, identifying and scoring failure modes (potential errors) for each process step, and generating remedial strategies to counteract them. Failure modes were scored using both an independent mathematical procedure and a team consensus procedure. Almost three-fifths of the 30 failure modes generated were scored differently by the 2 procedures, and for just more than one-third of cases, the score discrepancy was substantial. Using the Healthcare FMEA prioritization cutoff score, almost twice as many failure modes were prioritized by the consensus procedure than by the mathematical procedure. This is the first study to empirically demonstrate that different FMEA scoring procedures can score and prioritize failure modes differently. It found considerable variability in individual team members' opinions on scores, which highlights the subjective and qualitative nature of failure mode scoring. A consensus scoring procedure may be most appropriate for FMEA as it allows variability in individuals' scores and rationales to become apparent and to be discussed and resolved by the team. It may also yield team learning and communication benefits unlikely to result from a mathematical procedure.

Surface tearing modes in tokamaks

International Nuclear Information System (INIS)

Takizuka, Tomonori; Kurita, Gen-ichi; Azumi, Masafumi; Takeda, Tatsuoki

1985-10-01

Surface tearing modes in tokamaks are studied numerically and analytically. The eigenvalue problem is solved to obtain the growth rate and the mode structure. We investigate in detail dependences of the growth rate of the m/n = 2/1 resistive MHD modes on the safety factor at the plasma surface, current profile, wall position, and resistivity. The surface tearing mode moves the plasma surface even when the wall is close to the surface. The stability diagram for these modes is presented. (author)

Resonator modes and mode dynamics for an external cavity-coupled laser array

Science.gov (United States)

Nair, Niketh; Bochove, Erik J.; Aceves, Alejandro B.; Zunoubi, Mohammad R.; Braiman, Yehuda

2015-03-01

Employing a Fox-Li approach, we derived the cold-cavity mode structure and a coupled mode theory for a phased array of N single-transverse-mode active waveguides with feedback from an external cavity. We applied the analysis to a system with arbitrary laser lengths, external cavity design and coupling strengths to the external cavity. The entire system was treated as a single resonator. The effect of the external cavity was modeled by a set of boundary conditions expressed by an N-by-N frequency-dependent matrix relation between incident and reflected fields at the interface with the external cavity. The coupled mode theory can be adapted to various types of gain media and internal and external cavity designs.

Depressive disorders and anti-parkinson drug treatment

DEFF Research Database (Denmark)

Brandt-Christensen, M; Lopez, A G; Nilsson, F M

2007-01-01

OBJECTIVE: To estimate the rate of treatment with anti-parkinson drugs (APD) among patients with depression. METHOD: In a nationwide case register linkage study, all persons with a main diagnosis of depression during 5 years were identified. A control group of persons with diagnoses of osteoarthr...... that prescription of APD reflects the presence of Parkinson's disease, results support a positive statistical association between depressive disorders and Parkinson's disease.......OBJECTIVE: To estimate the rate of treatment with anti-parkinson drugs (APD) among patients with depression. METHOD: In a nationwide case register linkage study, all persons with a main diagnosis of depression during 5 years were identified. A control group of persons with diagnoses...... of osteoarthritis was included. The subsequent risk of getting treatment with APD was estimated for the two groups. Statistical analyses involved Poisson's regression and competing risk models. RESULTS: A total of 14 991 persons were included. The rate of getting APD was 2.57 (95% CI: 1.46-4.52) times higher...

Investigation of Avalanche Photodiodes and Multipixel Photon Counters as Light Detectors for Cosmic Rays

Science.gov (United States)

Vasquez, Jaime; Saavedra, Arthur; Ramos, Roxana; Tavares, Pablo; Wade, Marcus; Fan, Sewan; Haag, Brooke

2013-04-01

Through the Research Scholars Institute, students of Hartnell Community College experimented with the application of avalanche photodiodes (APDs) as cosmic ray detectors during the summer of 2012. An APD detector was coupled with a 10 meter long wavelength shifting fiber (WSF) wrapped around a cylindrical plastic scintillator to maximize signal detection. A photomultiplier tube (PMT) was used in conjunction to detect the same scintillation light caused by incoming cosmic rays. Two APD detectors were evaluated to confirm the viability of the setup. In addition, a similar setup was recently utilized to implement multi-pixel photon counters (MPPCs) as readout detectors. Under this configuration, a high gain preamplifier was used to amplify the signals for both the MPPC and APD detectors. We report on our results characterizing the MPPC and discuss its overall performance. Compared to the APD, our findings suggest that the MPPC detector has greater sensitivity in detecting weak light signals, and can be used in place of the PMT for certain counting applications.

Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications.

Science.gov (United States)

Nánási, Péter P; Magyar, János; Varró, András; Ördög, Balázs

2017-10-01

Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by I Ca , I Kr , and I Ks while increased by I Na , suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.

Effect of areal power density and relative humidity on corrosion resistant container performance

International Nuclear Information System (INIS)

Gansemer, J.D.

1994-10-01

The impact of the rewetting process on the performance of waste containers at the Yucca Mountain repository is analyzed. This paper explores the impact of the temperature-humidity relationships on pitting corrosion failure of stainless steel containers for different areal power densities (APDs)in the repository. It compares the likely performance of containers in a repository with a low APD, 55 Kw/acre, and a high APD, 110 kW/acre

Classification of typical and atypical antipsychotic drugs on the basis of dopamine D-1, D-2 and serotonin2 pKi values.

Science.gov (United States)

Meltzer, H Y; Matsubara, S; Lee, J C

1989-10-01

The pKi values of 13 reference typical and 7 reference atypical antipsychotic drugs (APDs) for rat striatal dopamine D-1 and D-2 receptor binding sites and cortical serotonin (5-HT2) receptor binding sites were determined. The atypical antipsychotics had significantly lower pKi values for the D-2 but not 5-HT2 binding sites. There was a trend for a lower pKi value for the D-1 binding site for the atypical APD. The 5-HT2 and D-1 pKi values were correlated for the typical APD whereas the 5-HT2 and D-2 pKi values were correlated for the atypical APD. A stepwise discriminant function analysis to determine the independent contribution of each pKi value for a given binding site to the classification as a typical or atypical APD entered the D-2 pKi value first, followed by the 5-HT2 pKi value. The D-1 pKi value was not entered. A discriminant function analysis correctly classified 19 of 20 of these compounds plus 14 of 17 additional test compounds as typical or atypical APD for an overall correct classification rate of 89.2%. The major contributors to the discriminant function were the D-2 and 5-HT2 pKi values. A cluster analysis based only on the 5-HT2/D2 ratio grouped 15 of 17 atypical + one typical APD in one cluster and 19 of 20 typical + two atypical APDs in a second cluster, for an overall correct classification rate of 91.9%. When the stepwise discriminant function was repeated for all 37 compounds, only the D-2 and 5-HT2 pKi values were entered into the discriminant function.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Heterogeneity Generates Re-entrant Substrate during Atrial Fibrillation and Anti-arrhythmic Drug Action: Mechanistic Insights from Canine Atrial Models

Science.gov (United States)

Varela, Marta; Hancox, Jules C.; Aslanidi, Oleg V.

2016-01-01

Anti-arrhythmic drug therapy is a frontline treatment for atrial fibrillation (AF), but its success rates are highly variable. This is due to incomplete understanding of the mechanisms of action of specific drugs on the atrial substrate at different stages of AF progression. We aimed to elucidate the role of cellular, tissue and organ level atrial heterogeneities in the generation of a re-entrant substrate during AF progression, and their modulation by the acute action of selected anti-arrhythmic drugs. To explore the complex cell-to-organ mechanisms, a detailed biophysical models of the entire 3D canine atria was developed. The model incorporated atrial geometry and fibre orientation from high-resolution micro-computed tomography, region-specific atrial cell electrophysiology and the effects of progressive AF-induced remodelling. The actions of multi-channel class III anti-arrhythmic agents vernakalant and amiodarone were introduced in the model by inhibiting appropriate ionic channel currents according to experimentally reported concentration-response relationships. AF was initiated by applied ectopic pacing in the pulmonary veins, which led to the generation of localized sustained re-entrant waves (rotors), followed by progressive wave breakdown and rotor multiplication in both atria. The simulated AF scenarios were in agreement with observations in canine models and patients. The 3D atrial simulations revealed that a re-entrant substrate was typically provided by tissue regions of high heterogeneity of action potential duration (APD). Amiodarone increased atrial APD and reduced APD heterogeneity and was more effective in terminating AF than vernakalant, which increased both APD and APD dispersion. In summary, the initiation and sustenance of rotors in AF is linked to atrial APD heterogeneity and APD reduction due to progressive remodelling. Our results suggest that anti-arrhythmic strategies that increase atrial APD without increasing its dispersion are

Dynamic Action Potential Restitution Contributes to Mechanical Restitution in Right Ventricular Myocytes From Pulmonary Hypertensive Rats.

Science.gov (United States)

Hardy, Matthew E L; Pervolaraki, Eleftheria; Bernus, Olivier; White, Ed

2018-01-01

We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9 Hz. Action potential waveforms recorded at 1 Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7 Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na + -channel blocker (5 μM) ranolazine or the intracellular Ca 2+ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller in MCT myocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus

Excursions through KK modes

Energy Technology Data Exchange (ETDEWEB)

Furuuchi, Kazuyuki [Manipal Centre for Natural Sciences, Manipal University,Manipal, Karnataka 576104 (India)

2016-07-07

In this article we study Kaluza-Klein (KK) dimensional reduction of massive Abelian gauge theories with charged matter fields on a circle. Since local gauge transformations change position dependence of the charged fields, the decomposition of the charged matter fields into KK modes is gauge dependent. While whole KK mass spectrum is independent of the gauge choice, the mode number depends on the gauge. The masses of the KK modes also depend on the field value of the zero-mode of the extra dimensional component of the gauge field. In particular, one of the KK modes in the KK tower of each massless 5D charged field becomes massless at particular values of the extra-dimensional component of the gauge field. When the extra-dimensional component of the gauge field is identified with the inflaton, this structure leads to recursive cosmological particle productions.

Excursions through KK modes

International Nuclear Information System (INIS)

Furuuchi, Kazuyuki

2016-01-01

In this article we study Kaluza-Klein (KK) dimensional reduction of massive Abelian gauge theories with charged matter fields on a circle. Since local gauge transformations change position dependence of the charged fields, the decomposition of the charged matter fields into KK modes is gauge dependent. While whole KK mass spectrum is independent of the gauge choice, the mode number depends on the gauge. The masses of the KK modes also depend on the field value of the zero-mode of the extra dimensional component of the gauge field. In particular, one of the KK modes in the KK tower of each massless 5D charged field becomes massless at particular values of the extra-dimensional component of the gauge field. When the extra-dimensional component of the gauge field is identified with the inflaton, this structure leads to recursive cosmological particle productions.

Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks

Science.gov (United States)

Kleiner, A.; Graves, J. P.; Brunetti, D.; Cooper, W. A.; Halpern, F. D.; Luciani, J.-F.; Lütjens, H.

2016-09-01

A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that infernal modes drive fast growing islands on neighbouring rational surfaces. Numerical simulations of such instabilities in a MAST-like configuration are performed with the initial value stability code XTOR-2F in the resistive frame. The evolution of magnetic islands are computed from XTOR-2F simulations and an analytical model is developed based on Rutherford’s theory in combination with a model of resistive infernal modes. The parameter {{Δ }\\prime} is extended from the linear phase to the non-linear phase. Additionally, the destabilising contribution due to a helically perturbed bootstrap current is considered. Comparing the numerical XTOR-2F simulations to the model, we find that coupling has a strong destabilising effect on (neoclassical) tearing modes and is able to seed 2/1 magnetic islands in situations when the standard NTM theory predicts stability.

Enhancement of mode-converted electron Bernstein wave emission during National Spherical Torus Experiment H-mode plasmas

International Nuclear Information System (INIS)

Taylor, G.; Efthimion, P.C.; Jones, B.; Le Blanc, B.P.; Maingi, R.

2002-01-01

A sudden, threefold increase in emission from fundamental electrostatic electron Bernstein waves (EBW) which mode convert and tunnel to the electromagnetic X-mode has been observed during high energy and particle confinement (H-mode) transitions in the National Spherical Torus Experiment (NSTX) plasma [M. Ono, S. Kaye, M. Peng et al., in Proceedings of the 17th IAEA Fusion Energy Conference (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135]. The mode-converted EBW emission viewed normal to the magnetic field on the plasma midplane increases when the density profile steepens in the vicinity of the mode conversion layer, which is located in the plasma scrape off. The measured conversion efficiency during the H-mode is consistent with the calculated EBW to X-mode conversion efficiency derived using edge density data. Calculations indicate that there may also be a small residual contribution to the measured X-mode electromagnetic radiation from polarization-scrambled, O-mode emission, converted from EBWs

Response of CMS avalanche photo-diodes to low energy neutrons

Science.gov (United States)

Brown, R. M.; Deiters, K.; Ingram, Q.; Renker, D.

2012-12-01

The response of the Avalanche Photo-diodes (APDs) installed in the CMS detector at the LHC to neutrons from 241AmBe and 252Cf sources is reported. Signals in size equivalent to those of up to 106 photo-electrons with the nominal APD gain are observed. Measurements with an APD with the protective epoxy coating removed and with the source placed behind the APD show that there is an important response due to recoil protons from neutron interactions with the hydrogen in the epoxy, in addition to signals from neutron interactions with the silicon of the diode. The effective gain of these signals is much smaller than the diode's nominal gain.

Mode-synthesizing atomic force microscopy and mode-synthesizing sensing

Science.gov (United States)

Passain, Ali; Thundat, Thomas George; Tetard, Laurene

2014-07-22

A method of analyzing a sample that includes applying a first set of energies at a first set of frequencies to a sample and applying, simultaneously with the applying the first set of energies, a second set of energies at a second set of frequencies, wherein the first set of energies and the second set of energies form a multi-mode coupling. The method further includes detecting an effect of the multi-mode coupling.

Mode synthesizing atomic force microscopy and mode-synthesizing sensing

Science.gov (United States)

Passian, Ali; Thundat, Thomas George; Tetard, Laurene

2013-05-17

A method of analyzing a sample that includes applying a first set of energies at a first set of frequencies to a sample and applying, simultaneously with the applying the first set of energies, a second set of energies at a second set of frequencies, wherein the first set of energies and the second set of energies form a multi-mode coupling. The method further includes detecting an effect of the multi-mode coupling.

Frequency-dependence of the slow force response.

Science.gov (United States)

von Lewinski, Dirk; Zhu, Danan; Khafaga, Mounir; Kockskamper, Jens; Maier, Lars S; Hasenfuss, Gerd; Pieske, Burkert

2008-05-01

Stretch induces biphasic inotropic effects in mammalian myocardium. A delayed component (slow force response, SFR) has been demonstrated in various species, however, experimental conditions varied and the underlying mechanisms are controversial. The physiological relevance of the SFR is poorly understood. Experiments were performed in ventricular muscle strips from failing human hearts and non-failing rabbit hearts. Upon stretch, twitch force was assessed at basal conditions (1 Hz, 37 degrees C) and after changing stimulation frequency with and without blockade of the Na+/H+-exchanger-1 (NHE1) or reverse-mode Na+/Ca2+-exchange (NCX). Action potential duration (APD) was assessed using floating electrodes. Low stimulation rates (0.2 Hz) potentiated and higher stimulation rates (2 and 3 Hz) reduced the SFR. The extent of SFR inhibition by NHE1 or NCX inhibition was not affected by stimulation rate. APD decreased at 0.2 Hz but was not altered at higher stimulation rates. The data demonstrate frequency-dependence of the SFR with greater positive inotropic effects at lower stimulation rates. Subcellular mechanisms underlying the SFR are not fundamentally affected by stimulation rate. The SFR may have more pronounced physiological effects at lower heart rates.

Airborne measurements of CO2 column concentrations made with a pulsed IPDA lidar using a multiple-wavelength-locked laser and HgCdTe APD detector

Science.gov (United States)

Abshire, James B.; Ramanathan, Anand K.; Riris, Haris; Allan, Graham R.; Sun, Xiaoli; Hasselbrack, William E.; Mao, Jianping; Wu, Stewart; Chen, Jeffrey; Numata, Kenji; Kawa, Stephan R.; Yang, Mei Ying Melissa; DiGangi, Joshua

2018-04-01

Here we report on measurements made with an improved CO2 Sounder lidar during the ASCENDS 2014 and 2016 airborne campaigns. The changes made to the 2011 version of the lidar included incorporating a rapidly wavelength-tunable, step-locked seed laser in the transmitter, using a much more sensitive HgCdTe APD detector and using an analog digitizer with faster readout time in the receiver. We also improved the lidar's calibration approach and the XCO2 retrieval algorithm. The 2014 and 2016 flights were made over several types of topographic surfaces from 3 to 12 km aircraft altitudes in the continental US. The results are compared to the XCO2 values computed from an airborne in situ sensor during spiral-down maneuvers. The 2014 results show significantly better performance and include measurement of horizontal gradients in XCO2 made over the Midwestern US that agree with chemistry transport models. The results from the 2016 airborne lidar retrievals show precisions of ˜ 0.7 parts per million (ppm) with 1 s averaging over desert surfaces, which is an improvement of about 8 times compared to similar measurements made in 2011. Measurements in 2016 were also made over fresh snow surfaces that have lower surface reflectance at the laser wavelengths. The results from both campaigns showed that the mean values of XCO2 retrieved from the lidar consistently agreed with those based on the in situ sensor to within 1 ppm. The improved precision and accuracy demonstrated in the 2014 and 2016 flights should benefit future airborne science campaigns and advance the technique's readiness for a space-based instrument.

Mixed-mode fracture of ceramics

Energy Technology Data Exchange (ETDEWEB)

Petrovic, J.J.

1985-01-01

The mixed-mode fracture behavior of ceramic materials is of importance for monolithic ceramics in order to predict the onset of fracture under generalized loading conditions and for ceramic composites to describe crack deflection toughening mechanisms. Experimental data on surface flaw mixed-mode fracture in various ceramics indicate that the flaw-plane normal stress at fracture decreases with increasing in-flaw-plane shear stress, although present data exhibit a fairly wide range in details of this sigma - tau relationship. Fracture from large cracks suggests that Mode II has a greater effect on Mode I fracture than Mode III. A comparison of surface flaw and large crack mixed-mode I-II fracture responses indicated that surface flaw behavior is influenced by shear resistance effects.

Consensus on the Definition of Advanced Parkinson’s Disease: A Neurologists-Based Delphi Study (CEPA Study

Directory of Open Access Journals (Sweden)

Maria-Rosario Luquin

2017-01-01

Full Text Available To date, no consensus exists on the key factors for diagnosing advanced Parkinson disease (APD. To obtain consensus on the definition of APD, we performed a prospective, multicenter, Spanish nationwide, 3-round Delphi study (CEPA study. An ad hoc questionnaire was designed with 33 questions concerning the relevance of several clinical features for APD diagnosis. In the first-round, 240 neurologists of the Spanish Movement Disorders Group participated in the study. The results obtained were incorporated into the questionnaire and both, results and questionnaire, were sent out to and fulfilled by 26 experts in Movement Disorders. Review of results from the second-round led to a classification of symptoms as indicative of “definitive,” “probable,” and “possible” APD. This classification was confirmed by 149 previous participating neurologists in a third-round, where 92% completely or very much agreed with the classification. Definitive symptoms of APD included disability requiring help for the activities of daily living, presence of motor fluctuations with limitations to perform basic activities of daily living without help, severe dysphagia, recurrent falls, and dementia. These results will help neurologists to identify some key factors in APD diagnosis, thus allowing users to categorize the patients for a homogeneous recognition of this condition.

Auditory processing disorders: an update for speech-language pathologists.

Science.gov (United States)

DeBonis, David A; Moncrieff, Deborah

2008-02-01

Unanswered questions regarding the nature of auditory processing disorders (APDs), how best to identify at-risk students, how best to diagnose and differentiate APDs from other disorders, and concerns about the lack of valid treatments have resulted in ongoing confusion and skepticism about the diagnostic validity of this label. This poses challenges for speech-language pathologists (SLPs) who are working with school-age children and whose scope of practice includes APD screening and intervention. The purpose of this article is to address some of the questions commonly asked by SLPs regarding APDs in school-age children. This article is also intended to serve as a resource for SLPs to be used in deciding what role they will or will not play with respect to APDs in school-age children. The methodology used in this article included a computerized database review of the latest published information on APD, with an emphasis on the work of established researchers and expert panels, including articles from the American Speech-Language-Hearing Association and the American Academy of Audiology. The article concludes with the authors' recommendations for continued research and their views on the appropriate role of the SLP in performing careful screening, making referrals, and supporting intervention.

Laser annealing heals radiation damage in avalanche photodiodes

Energy Technology Data Exchange (ETDEWEB)

Lim, Jin Gyu [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Electrical and Computer Engineering, Waterloo, ON (Canada); Anisimova, Elena; Higgins, Brendon L.; Bourgoin, Jean-Philippe [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada); Jennewein, Thomas [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada); Canadian Institute for Advanced Research, Quantum Information Science Program, Toronto, ON (Canada); Makarov, Vadim [University of Waterloo, Institute for Quantum Computing, Waterloo, ON (Canada); University of Waterloo, Department of Electrical and Computer Engineering, Waterloo, ON (Canada); University of Waterloo, Department of Physics and Astronomy, Waterloo, ON (Canada)

2017-12-15

Avalanche photodiodes (APDs) are a practical option for space-based quantum communications requiring single-photon detection. However, radiation damage to APDs significantly increases their dark count rates and thus reduces their useful lifetimes in orbit. We show that high-power laser annealing of irradiated APDs of three different models (Excelitas C30902SH, Excelitas SLiK, and Laser Components SAP500S2) heals the radiation damage and several APDs are restored to typical pre-radiation dark count rates. Of nine samples we test, six APDs were thermally annealed in a previous experiment as another solution to mitigate the radiation damage. Laser annealing reduces the dark count rates further in all samples with the maximum dark count rate reduction factor varying between 5.3 and 758 when operating at -80 C. This indicates that laser annealing is a more effective method than thermal annealing. The illumination power to reach these reduction factors ranges from 0.8 to 1.6 W. Other photon detection characteristics, such as photon detection efficiency, timing jitter, and afterpulsing probability, fluctuate but the overall performance of quantum communications should be largely unaffected by these variations. These results herald a promising method to extend the lifetime of a quantum satellite equipped with APDs. (orig.)

Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier

DEFF Research Database (Denmark)

Alkeskjold, Thomas Tanggaard; Scolari, Lara; Broeng, Jes

2011-01-01

bandgap structure. The structure allows resonant coupling of higher-order modes from the core and acts as a spatially Distributed Mode Filter (DMF). With this approach, we demonstrate passive SM performance in an only ~50cm long and straight ytterbium-doped rod fiber. The amplifier has a mode field...... diameter of ∼59Lim at 1064nm and exhibits a pump absorption of 27dB/m at 976nm. © 2011 Optical Society of America....

Interferometric characterization of few-mode fibers (FMF) for mode-division multiplexing (MDM)

OpenAIRE

Muliar, Olena; Usuga Castaneda, Mario A.; Rottwitt, Karsten; Lægsgaard, Jesper

2015-01-01

The rapid growth of global data traffic demands the continuous search for new technologies and systems that could increase transmission capacity in optical links and recent experiments show that to do so, it is advantageous to explore new degrees of freedom such as polarization, wavelength or optical modes. Mode division multiplexing (MDM) appears in this context as a promising and viable solution for such capacity increase, since it utilizes multiple spatial modes of an optical fiber as indi...

Nonlinear drift tearing mode

International Nuclear Information System (INIS)

Zelenyj, L.M.; Kuznetsova, M.M.

1989-01-01

Nonlinear study of magnetic perturbation development under single-mode conditions in collision-free plasma in configurations with the magnetic field shear is investigated. Results are obtained with regard of transverse component of electrical field and its effect on ion dynamics within wide range of ion Larmor radius value and values of magnetic field shear. Increments of nonlinear drift tearing mode are obtained and it is shown that excitation drastic conditions of even linearly stable modes are possible. Mechanism of instability nonlinear stabilization is considered and the value of magnetic island at the saturation threshold is estimeted. Energy of nonlinear drift tearing mode is discussed

Constructing petal modes from the coherent superposition of Laguerre-Gaussian modes

Science.gov (United States)

Naidoo, Darryl; Forbes, Andrew; Ait-Ameur, Kamel; Brunel, Marc

2011-03-01

An experimental approach in generating Petal-like transverse modes, which are similar to what is seen in porro-prism resonators, has been successfully demonstrated. We hypothesize that the petal-like structures are generated from a coherent superposition of Laguerre-Gaussian modes of zero radial order and opposite azimuthal order. To verify this hypothesis, visually based comparisons such as petal peak to peak diameter and the angle between adjacent petals are drawn between experimental data and simulated data. The beam quality factor of the Petal-like transverse modes and an inner product interaction is also experimentally compared to numerical results.

X-ray fractography of fatigue fracture surface under mode I and mode III loading

International Nuclear Information System (INIS)

Akiniwa, Yoshiaki; Tanaka, Keisuke; Tsumura, Tsuyoshi

2001-01-01

The propagation behavior of a circumferential fatigue crack in cylindrical bars of a carbon steel (JIS SGV410) and a stainless steel (JIS SUS316NG) was investigated under cyclic axial and torsional loadings. The J-integral range was used as a fracture mechanics parameter. When compared at the same J-integral range, the crack propagation rate under mode III was smaller than that under mode I. Parallel markings perpendicular to the crack propagation direction were observed on the fatigue fracture surface obtained under mode III loading. The residual stresses in the radial direction, σ r , and in the tangential direction, σ θ , were measured for both mode I and mode III fatigue fracture surfaces. For mode I fracture surface, σ r was tension, and was almost constant irrespective of the applied J-integral range. σ θ was close to zero for both materials. On the other hand, for mode III, σ r and σ θ were compression. For SUS316NG steel, the compressive stress of σ θ increased with the J-integral range. For SGV410 steel, the change of σ θ with the J-integral range was small. The breadth of diffraction profiles increased with J-integral range for both mode I and III. The breadth was found to be a good parameter to evaluate the applied J-integral range. (author)

Comprehensive comparison of macro-strain mode and displacement mode based on different sensing technologies

Science.gov (United States)

Hong, Wan; Zhang, Jian; Wu, Gang; Wu, Zhishen

2015-01-01

A comprehensive comparison of macro-strain mode and displacement mode obtained from distributed macro-strain sensing and high-density point sensing (such as accelerometers) technologies is presented in this paper. Theoretical derivation reveals that displacement mode shape from accelerometers and modal macro-strain from distributed macro-strain sensors can be converted into each other. However, it is realized that displacement mode shape as global behavior of a structure can still be calculated with high-precision from modal macro-strain considering measurement errors in practical monitoring, whereas modal macro-strain can hardly be accurately achieved from displacement mode shape when signals are corrupted with noise in practical monitoring. Simulation and experiment results show that the calculated displacement mode shapes are very close to the actual ones even if the noise level reaches 5%. Meanwhile, damage index using measured modal macro-strain is still effective when the measurements are corrupted with 5% noise which is reliable for damage detection in practical monitoring. Calculating modal macro-strain from noise-polluted displacement mode shape will cause an unacceptable error if the noise level reaches only 0.5%, which has been verified in the simulation.

Biomolecule detection using a silicon nanoribbon: accumulation mode versus inversion mode

International Nuclear Information System (INIS)

Elfstroem, Niklas; Linnros, Jan

2008-01-01

Silicon nanoribbons were fabricated using standard optical lithography from silicon on insulator material with top silicon layer thicknesses of 100, 60 and 45 nm. Electrically these work as Schottky-barrier field-effect transistors and, depending on the substrate voltage, electron or hole injection is possible. The current through the nanoribbon is extremely sensitive to charge changes at the oxidized top surface and can be used for biomolecule detection in a liquid. We show that for detection of streptavidin molecules the response is larger in the accumulation mode than in the inversion mode, although not leading to higher detection sensitivity due to increased noise. The effect is attributed to the location in depth of the conducting channel, which for holes is closer to the screened surface charges of the biomolecules. Furthermore, the response increases for decreasing silicon thickness in both the accumulation mode and the inversion mode. The results are verified qualitatively and quantitatively through a two-dimensional simulation model on a cross section along the nanoribbon device

Passive harmonic mode locking by mode selection in Fabry-Perot diode lasers with patterned effective index.

Science.gov (United States)

Bitauld, David; Osborne, Simon; O'Brien, Stephen

2010-07-01

We demonstrate passive harmonic mode locking of a quantum-well laser diode designed to support a discrete comb of Fabry-Perot modes. Spectral filtering of the mode spectrum was achieved using a nonperiodic patterning of the cavity effective index. By selecting six modes spaced at twice the fundamental mode spacing, near-transform-limited pulsed output with 2 ps pulse duration was obtained at a repetition rate of 100 GHz.

Amygdala reactivity and negative emotionality: divergent correlates of antisocial personality and psychopathy traits in a community sample.

Science.gov (United States)

Hyde, Luke W; Byrd, Amy L; Votruba-Drzal, Elizabeth; Hariri, Ahmad R; Manuck, Stephen B

2014-02-01

Previous studies have emphasized that antisocial personality disorder (APD) and psychopathy overlap highly but differ critically in several features, notably negative emotionality (NEM) and possibly amygdala reactivity to social signals of threat and distress. Here we examined whether dimensions of psychopathy and APD correlate differentially with NEM and amygdala reactivity to emotional faces. Testing these relationships among healthy individuals, dimensions of psychopathy and APD were generated by the profile matching technique of Lynam and Widiger (2001), using facet scales of the NEO Personality Inventory-Revised, and amygdala reactivity was measured using a well-established emotional faces task, in a community sample of 103 men and women. Higher psychopathy scores were associated with lower NEM and lower amygdala reactivity, whereas higher APD scores were related to greater NEM and greater amygdala reactivity, but only after overlapping variance in APD and psychopathy was adjusted for in the statistical model. Amygdala reactivity did not mediate the relationship of APD and psychopathy scores to NEM. Supplemental analyses also compared other measures of factors within psychopathy in predicting NEM and amygdala reactivity and found that Factor 2 psychopathy was positively related to NEM and amygdala reactivity across measures of psychopathy. The overall findings replicate seminal observations on NEM in psychopathy by Hicks and Patrick (2006) and extend this work to neuroimaging in a normative population. They also suggest that one critical way in which APD and psychopathy dimensions may differ in their etiology is through their opposing levels of NEM and amygdala reactivity to threat. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Impaired Na⁺-dependent regulation of acetylcholine-activated inward-rectifier K⁺ current modulates action potential rate dependence in patients with chronic atrial fibrillation.

Science.gov (United States)

Voigt, Niels; Heijman, Jordi; Trausch, Anne; Mintert-Jancke, Elisa; Pott, Lutz; Ravens, Ursula; Dobrev, Dobromir

2013-08-01

Shortened action-potential duration (APD) and blunted APD rate adaptation are hallmarks of chronic atrial fibrillation (cAF). Basal and muscarinic (M)-receptor-activated inward-rectifier K(+) currents (IK1 and IK,ACh, respectively) contribute to regulation of human atrial APD and are subject to cAF-dependent remodeling. Intracellular Na(+) ([Na(+)]i) enhances IK,ACh in experimental models but the effect of [Na(+)]i-dependent regulation of inward-rectifier K(+) currents on APD in human atrial myocytes is currently unknown. Here, we report a [Na(+)]i-dependent inhibition of outward IK1 in atrial myocytes from sinus rhythm (SR) or cAF patients. In contrast, IK,ACh activated by carbachol, a non-selective M-receptor agonist, increased with elevation of [Na(+)]i in SR. This [Na(+)]i-dependent IK,ACh regulation was absent in cAF. Including [Na(+)]i dependence of IK1 and IK,ACh in a recent computational model of the human atrial myocyte revealed that [Na(+)]i accumulation at fast rates inhibits IK1 and blunts physiological APD rate dependence in both groups. [Na(+)]i-dependent IK,ACh augmentation at fast rates increased APD rate dependence in SR, but not in cAF. These results identify impaired Na(+)-sensitivity of IK,ACh as one potential mechanism contributing to the blunted APD rate dependence in patients with cAF. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes". Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

The H-mode operational window as determined from the ITER H-mode database

International Nuclear Information System (INIS)

Ryter, F.; Kardaun, O.J.W.F.; Stroth, U.

1994-01-01

The H-mode is a promising regime for fusion reactors and it is essential to be able to predict its operational window in future devices. The 'H-Mode Database Working Group' started in 1992 to gather, analyze and compare H-mode threshold data from several divertor tokamaks so that predictions could be made. The database and first results were presented and the threshold database has been improved and extended since. The work has two objectives: 1) to predict the minimum heating power necessary to reach the H-mode in future devices, 2) to contribute to physics studies of the L-H transition. (author) 11 refs., 2 figs

Tilting mode in field-reversed configurations

International Nuclear Information System (INIS)

Schwarzmeier, J.L.; Barnes, D.C.; Lewis, H.R.; Seyler, C.E.; Shestakov, A.I.

1982-01-01

Field Reversed Configurations (FRCs) experimentally have exhibited remarkable stability on the magnetohydrodynamic (MHD) timescale, despite numerous MHD calculations showing FRCs to be unstable. It is easy to believe that local modes are stabilized by finite Larmor radius (FLR) effects, but more puzzling is the apparent stability of FRCs against global modes, where one would expect FLR effects to be less important. In this paper we study the tilting mode, which MHD has shown to be a rapidly growing global mode. The tilting mode in FRCs is driven by the pressure gradient, and magnetic compression and field line bending are the stabilizing forces. A schematic of the evolution of the tilting mode is shown. The tilting mode is considered dangerous, because it would lead to rapid tearing across the separatrix. Unlike spheromaks, the tilting mode in FRCs has a separatrix that is fixed in space, so that the mode is strictly internal

Streaming gravity mode instability

International Nuclear Information System (INIS)

Wang Shui.

1989-05-01

In this paper, we study the stability of a current sheet with a sheared flow in a gravitational field which is perpendicular to the magnetic field and plasma flow. This mixing mode caused by a combined role of the sheared flow and gravity is named the streaming gravity mode instability. The conditions of this mode instability are discussed for an ideal four-layer model in the incompressible limit. (author). 5 refs

Discrimination of orbital angular momentum modes of the terahertz vortex beam using a diffractive mode transformer.

Science.gov (United States)

Liu, Changming; Wei, Xuli; Niu, Liting; Wang, Kejia; Yang, Zhengang; Liu, Jinsong

2016-06-13

We present an efficient method to discriminate orbital angular momentum (OAM) of the terahertz (THz) vortex beam using a diffractive mode transformer. The mode transformer performs a log-polar coordinate transformation of the input THz vortex beam, which consists of two 3D-printed diffractive elements. A following lens separates each transformed OAM mode to a different lateral position in its focal plane. This method enables a simultaneous measurement over multiple OAM modes of the THz vortex beam. We experimentally demonstrate the measurement of seven individual OAM modes and two multiplexed OAM modes, which is in good agreement with simulations.

Suppression of an acoustic mode by an elastic mode of a liquid-filled spherical shell resonator.

Science.gov (United States)

Lonzaga, Joel B; Raymond, Jason L; Mobley, Joel; Gaitan, D Felipe

2011-02-01

The purpose of this paper is to report on the suppression of an approximately radial (radially symmetric) acoustic mode by an elastic mode of a water-filled, spherical shell resonator. The resonator, which has a 1-in. wall thickness and a 9.5-in. outer diameter, was externally driven by a small transducer bolted to the external wall. Experiments showed that for the range of drive frequencies (19.7-20.6 kHz) and sound speeds in water (1520-1570 m/s) considered in this paper, a nonradial (radially nonsymmetric) mode was also excited, in addition to the radial mode. Furthermore, as the sound speed in the liquid was changed, the resonance frequency of the nonradial mode crossed with that of the radial one and the amplitude of the latter was greatly reduced near the crossing point. The crossing of the eigenfrequency curves of these two modes was also predicted theoretically. Further calculations demonstrated that while the radial mode is an acoustic one associated with the interior fluid, the nonradial mode is an elastic one associated with the shell. Thus, the suppression of the radial acoustic mode is apparently caused by the overlapping with the nonradial elastic mode near the crossing point.

Informed Design of Mixed-Mode Surveys : Evaluating mode effects on measurement and selection error

NARCIS (Netherlands)

Klausch, Thomas|info:eu-repo/dai/nl/341427306

2014-01-01

“Mixed-mode designs” are innovative types of surveys which combine more than one mode of administration in the same project, such as surveys administered partly on the web (online), on paper, by telephone, or face-to-face. Mixed-mode designs have become increasingly popular in international survey

Influences of multiple low-n modes on n=1 resistive wall mode identification and feedback control

International Nuclear Information System (INIS)

In, Y.; Kim, J.; Kim, J. S.; Garofalo, A. M.; Jackson, G. L.; La Haye, R. J.; Strait, E. J.; Okabayashi, M.; Reimerdes, H.

2008-01-01

It is well known in theory that even after the n=1 resistive wall mode (RWM) is suppressed, the other low-n modes, such as n=2 or 3, can appear sequentially, as β increases. In recent DIII-D experiments [J. L. Luxon, Nucl. Fusion 42, 614 (2002)], we found such an example that supports the theoretical prediction: while the n=1 mode was suppressed, an n=3 mode grew dominant, leading to a β collapse. The n=1 RWM suppression was likely due to a combination of rotational stabilization and n=1 RWM feedback. The multiple RWM identification was performed using an expanded matched filter, where n=1 and n=3 RWM basis vectors are simultaneously considered. Taking advantage of the expanded matched filter, we found that an n=3 mode following an edge-localized-mode burst grew almost linearly for several milliseconds without being hindered. This n=3 mode appeared responsible for the β collapse (down to the n=3 no-wall limit), as well as for a drop in toroidal rotation. A preliminary analysis suggests that the identity of the n=3 mode could be related to the n=3 RWM (possibly the first observation in tokamak experiments), while the impact of the n=3 mode was not as destructive as that of n=1 RWM. A numerical postprocessing of Mirnov probes showed that the n=2 mode was also unstable, consistent with the theoretical prediction. In practice, since the presence of an n=3 mode can interfere with the existing n=1 RWM identification, multiple low-n mode identification is deemed essential not only to detect n>1 mode, but also to provide accurate n=1 RWM identification and feedback control.

A novel MUX/DEMUX based on few-mode FBG for mode division multiplexing system

Science.gov (United States)

Han, Yueyu; Hu, Guijun

2016-05-01

In this paper, a novel mode multiplexer/demultiplexer (MUX/DEMUX) based on few-mode fiber Bragg gratings (FBG) has been proposed. The principle of the MUX/DEMUX based on few-mode FBG has been described in detail, and crosstalk of better than -20 dB is obtained experimentally. Then a 2×2 division multiplexing (MDM) system has been established with the MUX/DEMUX we proposed. The transmission experiment of 2×10 Gbps PRBS has been achieved successfully, which are carried by LP01 mode and LP11 mode, respectively. When the receiver sensitivity is greater than -14 dB m and -10 dB m, the BER can both reach 10-3 for B2B and 10 km transmission, respectively.

Mode-routed fiber-optic add-drop filter

Science.gov (United States)

Moslehi, Behzad (Inventor); Black, Richard James (Inventor); Shaw, Herbert John (Inventor)

2000-01-01

New elements mode-converting two-mode grating and mode-filtering two-mode coupler are disclosed and used as elements in a system for communications, add-drop filtering, and strain sensing. Methods of fabrication for these new two-mode gratings and mode-filtering two-mode couplers are also disclosed.

Fiber cavities with integrated mode matching optics.

Science.gov (United States)

Gulati, Gurpreet Kaur; Takahashi, Hiroki; Podoliak, Nina; Horak, Peter; Keller, Matthias

2017-07-17

In fiber based Fabry-Pérot Cavities (FFPCs), limited spatial mode matching between the cavity mode and input/output modes has been the main hindrance for many applications. We have demonstrated a versatile mode matching method for FFPCs. Our novel design employs an assembly of a graded-index and large core multimode fiber directly spliced to a single mode fiber. This all-fiber assembly transforms the propagating mode of the single mode fiber to match with the mode of a FFPC. As a result, we have measured a mode matching of 90% for a cavity length of ~400 μm. This is a significant improvement compared to conventional FFPCs coupled with just a single mode fiber, especially at long cavity lengths. Adjusting the parameters of the assembly, the fundamental cavity mode can be matched with the mode of almost any single mode fiber, making this approach highly versatile and integrable.

ELM phenomenon as an interaction between bootstrap-current driven peeling modes and pressure-driven ballooning modes

International Nuclear Information System (INIS)

Saarelma, S.; Kurki-Suonio, T.; Guenter, S.; Zehrfeld, H.-P.

2000-01-01

An ELMy ASDEX Upgrade plasma equilibrium is reconstructed taking into account the bootstrap current. The peeling mode stability of the equilibrium is numerically analysed using the GATO [1] code, and it is found that the bootstrap current can drive the plasma peeling mode unstable. A high-n ballooning mode stability analysis of the equilibria revealed that, while destabilizing the peeling modes, the bootstrap current has a stabilizing effect on the ballooning modes. A combination of these two instabilities is a possible explanation for the type I ELM phenomenon. A triangularity scan showed that increasing triangularity stabilizes the peeling modes and can produce ELM-free periods observed in the experiments. (author)

The Association between Peritoneal Dialysis Modality and Peritonitis

Science.gov (United States)

Johnson, David W.; McDonald, Stephen P.; Boudville, Neil; Borlace, Monique; Badve, Sunil V.; Sud, Kamal; Clayton, Philip A.

2014-01-01

Background and objectives There is conflicting evidence comparing peritonitis rates among patients treated with continuous ambulatory peritoneal dialysis (CAPD) or automated peritoneal dialysis (APD). This study aims to clarify the relationship between peritoneal dialysis (PD) modality (APD versus CAPD) and the risk of developing PD-associated peritonitis. Design, setting, participants, & measurements This study examined the association between PD modality (APD versus CAPD) and the risks, microbiology, and clinical outcomes of PD-associated peritonitis in 6959 incident Australian PD patients between October 1, 2003, and December 31, 2011, using data from the Australia and New Zealand Dialysis and Transplant Registry. Median follow-up time was 1.9 years. Results Patients receiving APD were younger (60 versus 64 years) and had fewer comorbidities. There was no association between PD modality and time to first peritonitis episode (adjusted hazard ratio [HR] for APD versus CAPD, 0.98; 95% confidence interval [95% CI], 0.91 to 1.07; P=0.71). However, there was a lower hazard of developing Gram-positive peritonitis with APD than CAPD, which reached borderline significance (HR, 0.90; 95% CI, 0.80 to 1.00; P=0.05). No statistically significant difference was found in the risk of hospitalizations (odds ratio, 1.12; 95% CI, 0.93 to 1.35; P=0.22), but there was a nonsignificant higher likelihood of 30-day mortality (odds ratio, 1.33; 95% CI, 0.93 to 1.88; P=0.11) at the time of the first episode of peritonitis for patients receiving APD. For all peritonitis episodes (including subsequent episodes of peritonitis), APD was associated with lower rates of culture-negative peritonitis (incidence rate ratio [IRR], 0.81; 95% CI, 0.69 to 0.94; P=0.002) and higher rates of gram-negative peritonitis (IRR, 1.28; 95% CI, 1.13 to 1.46; P=0.01). Conclusions PD modality was not associated with a higher likelihood of developing peritonitis. However, APD was associated with a borderline

Mode I and mixed mode crack-tip fields in strain gradient plasticity

DEFF Research Database (Denmark)

Goutianos, Stergios

2011-01-01

Strain gradients develop near the crack-tip of Mode I or mixed mode cracks. A finite strain version of the phenomenological strain gradient plasticity theory of Fleck–Hutchinson (2001) is used here to quantify the effect of the material length scales on the crack-tip stress field for a sharp...... stationary crack under Mode I and mixed mode loading. It is found that for material length scales much smaller than the scale of the deformation gradients, the predictions converge to conventional elastic–plastic solutions. For length scales sufficiently large, the predictions converge to elastic solutions....... Thus, the range of length scales over which a strain gradient plasticity model is necessary is identified. The role of each of the three material length scales, incorporated in the multiple length scale theory, in altering the near-tip stress field is systematically studied in order to quantify...

Thermal Operating Modes

International Nuclear Information System (INIS)

Bechtel SAIC Company

2002-01-01

Higher and lower temperature operating modes (e.g., above and below the boiling point of water) are alternative approaches to managing the heat produced by the radioactive decay of spent nuclear fuel. Current analyses indicate that a repository at the Yucca Mountain site is likely to comply with applicable safety standards regardless of the particular thermal operating mode. Both modes have potential advantages and disadvantages. With a higher temperature operating mode (HTOM), waste packages (WPs) can be placed closer together. This reduces the number of drifts, the required emplacement area, construction costs, and occupational risks to construction workers. In addition, the HTOM would minimize the amount of water that might contact the waste for hundreds of years after closure. On the other hand, higher temperatures introduce uncertainties in the understanding of the long-term performance of the repository because of uncertainties in the thermal effects on WP lifetime and the near-field environment around the drifts. A lower temperature operating mode (LTOM) has the potential to reduce uncertainties in long-term performance of the repository by limiting the effects of temperature on WP lifetime and on the near-field environment around the drifts. Depending on the combination of operating parameters, a LTOM could require construction of additional drifts, a larger emplacement area, increased construction costs, increased occupational risks to construction works, and a longer period of ventilation than a HTOM. The repository design for the potential Yucca Mountain site is flexible and can be constructed and operated in various operating modes to achieve specific technical objectives, accommodate future policy decisions, and use of new information. For example, the flexible design can be operated across a range of temperatures and can be tailored to achieve specific thermal requirements in the future. To accommodate future policy decisions, the repository can be

Application of avalanche photodiode for soft X-ray pulse-height analyses in the Ht-7 tokamak

CERN Document Server

Shi Yue Jiang; Hu Li Qun; Sun Yan Jun; LiuSheng; Ling Bil

2002-01-01

An avalanche photodiode (APD) has been used as soft X-ray energy pulse-height analysis system for the measurement of the electron temperature on the HT-7 tokamak. The experimental results obtained with the APD with its inferior energy resolution show a little difference compared to the conventional high energy-resolution Si (Li) detector. Both numerical analysis and experimental results prove that the APD is good enough for application of the electron temperature measurement in tokamaks.

Nonlinear saturation of the trapped-ion mode by mode coupling in two dimensions

International Nuclear Information System (INIS)

Cohen, B.I.; Tang, W.M.

1977-01-01

A study of the nonlinear saturation by mode coupling of the dissipative trapped-ion mode is presented in which both radial and poloidal variations are considered. The saturation mechanism consists of the nonlinear coupling via E x B convection of energy from linearly unstable modes to stable modes. Stabilization is provided at short poloidal wavelengths by Landau damping from trapped and circulating ions, at short radial wavelengths by effects associated with the finite ion banana excursions and at long wavelengths by ion collisions. A one-dimensional, nonlinear partial differential equation for the electrostatic potential derived in earlier work is extended to two dimensions and to third order in amplitude. Included systematically are kinetic effects, e.g., Landau damping and its spatial dependence due to magnetic shear. The stability and accessibility of equilibria are considered in detail for cases far from as well as close to marginal stability. In the first case three-wave interactions are found to be important when the spectrum of unstable modes is sufficiently narrow. In the latter case, it is found that for a single unstable mode, a four-wave interaction can provide the dominant saturation mechanism. Cross-field transport is calculated, and the scaling of results is considered for tokamak parameters

Linear stability of tearing modes

International Nuclear Information System (INIS)

Cowley, S.C.; Kulsrud, R.M.; Hahm, T.S.

1986-05-01

This paper examines the stability of tearing modes in a sheared slab when the width of the tearing layer is much smaller than the ion Larmor radius. The ion response is nonlocal, and the quasineutrality retains its full integal form. An expansion procedure is introduced to solve the quasineutrality equation in powers of the width of the tearing layer over the ion Larmor radius. The expansion procedure is applied to the collisionless and semi-collisional tearing modes. The first order terms in the expansion we find to be strongly stabilizing. The physics of the mode and of the stabilization is discussed. Tearing modes are observed in experiments even though the slab theory predicts stability. It is proposed that these modes grow from an equilibrium with islands at the rational surfaces. If the equilibrium islands are wider than the ion Larmor radius, the mode is unstable when Δ' is positive

Completeness of non-normalizable modes

International Nuclear Information System (INIS)

Mannheim, Philip D; Simbotin, Ionel

2006-01-01

We establish the completeness of some characteristic sets of non-normalizable modes by constructing fully localized square steps out of them, with each such construction expressly displaying the Gibbs phenomenon associated with trying to use a complete basis of modes to fit functions with discontinuous edges. As well as being of interest in and of itself, our study is also of interest to the recently introduced large extra dimension brane-localized gravity program of Randall and Sundrum, since the particular non-normalizable mode bases that we consider (specifically the irregular Bessel functions and the associated Legendre functions of the second kind) are associated with the tensor gravitational fluctuations which occur in those specific brane worlds in which the embedding of a maximally four-symmetric brane in a five-dimensional anti-de Sitter bulk leads to a warp factor which is divergent. Since the brane-world massless four-dimensional graviton has a divergent wavefunction in these particular cases, its resulting lack of normalizability is thus not seen to be any impediment to its belonging to a complete basis of modes, and consequently its lack of normalizability should not be seen as a criterion for not including it in the spectrum of observable modes. Moreover, because the divergent modes we consider form complete bases, we can even construct propagators out of them in which these modes appear as poles with residues which are expressly finite. Thus, even though normalizable modes appear in propagators with residues which are given as their finite normalization constants, non-normalizable modes can just as equally appear in propagators with finite residues too-it is just that such residues will not be associated with bilinear integrals of the modes

Resonant MHD modes with toroidal coupling

International Nuclear Information System (INIS)

Connor, J.W.; Hastie, R.J.; Taylor, J.B.

1990-07-01

This is part 2 of a study of resonant perturbations, such as resistive tearing and ballooning modes, in a torus. These are described by marginal ideal mhd equations in the regions between resonant surfaces; matching across these surfaces provides the dispersion relation. In part 1 we described how all the necessary information from the ideal mhd calculations could be represented by a so-called E-matrix. We also described the calculation of this E-matrix for tearing modes (even parity in perturbed magnetic field) in a large aspect ratio torus. There the toroidal modes comprise coupled cylinder tearing modes and the E-matrix is a generalization of the familiar Δ' quantity in a cylinder. In the present paper we discuss resistive ballooning, or twisting-modes, which have odd-parity in perturbed magnetic field. We show that, unlike the tearing modes, these odd-parity modes are instrinsically toroidal and are not directly related to the odd-parity modes in a cylinder. This is evident from the analysis of the high-n limit in ballooning-space, where a transition from a stable Δ' to an unstable Δ' occurs for the twisting mode when the ballooning effect exceeds the interchange effect, which can occur even at large aspect ratio (as in a tokamak). Analysis of the high-n limit in coordinate space, rather than ballooning space, clarifies this singular behaviour and indicates how one may define twisting-mode Δ'. It also yields a prescription for treating low-n twisting modes and a method for calculating an E-matrix for resistive ballooning modes in a large aspect ratio tokamak. The elements of this matrix are given in terms of cylindrical tearing mode solutions

Mode Equivalence of Health Indicators Between Data Collection Modes and Mixed-Mode Survey Designs in Population-Based Health Interview Surveys for Children and Adolescents: Methodological Study

Science.gov (United States)

Hoffmann, Robert; Houben, Robin; Krause, Laura; Kamtsiuris, Panagiotis; Gößwald, Antje

2018-01-01

Background The implementation of an Internet option in an existing public health interview survey using a mixed-mode design is attractive because of lower costs and faster data availability. Additionally, mixed-mode surveys can increase response rates and improve sample composition. However, mixed-mode designs can increase the risk of measurement error (mode effects). Objective This study aimed to determine whether the prevalence rates or mean values of self- and parent-reported health indicators for children and adolescents aged 0-17 years differ between self-administered paper-based questionnaires (SAQ-paper) and self-administered Web-based questionnaires (SAQ-Web), as well as between a single-mode control group and different mixed-mode groups. Methods Data were collected for a methodological pilot of the third wave of the "German Health Interview and Examination Survey for Children and Adolescents". Questionnaires were completed by parents or adolescents. A population-based sample of 11,140 children and adolescents aged 0-17 years was randomly allocated to 4 survey designs—a single-mode control group with paper-and-pencil questionnaires only (n=970 parents, n=343 adolescents)—and 3 mixed-mode designs, all of which offered Web-based questionnaire options. In the concurrent mixed-mode design, both questionnaires were offered at the same time (n=946 parents, n=290 adolescents); in the sequential mixed-mode design, the SAQ-Web was sent first, followed by the paper questionnaire along with a reminder (n=854 parents, n=269 adolescents); and in the preselect mixed-mode design, both options were offered and the respondents were asked to request the desired type of questionnaire (n=698 parents, n=292 adolescents). In total, 3468 questionnaires of parents of children aged 0-17 years (SAQ-Web: n=708; SAQ-paper: n=2760) and 1194 questionnaires of adolescents aged 11-17 years (SAQ-Web: n=299; SAQ-paper: n=895) were analyzed. Sociodemographic characteristics and a broad

Homogeneous modes of cosmological instantons

International Nuclear Information System (INIS)

Gratton, Steven; Turok, Neil

2001-01-01

We discuss the O(4) invariant perturbation modes of cosmological instantons. These modes are spatially homogeneous in Lorentzian spacetime and thus not relevant to density perturbations. But their properties are important in establishing the meaning of the Euclidean path integral. If negative modes are present, the Euclidean path integral is not well defined, but may nevertheless be useful in an approximate description of the decay of an unstable state. When gravitational dynamics is included, counting negative modes requires a careful treatment of the conformal factor problem. We demonstrate that for an appropriate choice of coordinate on phase space, the second order Euclidean action is bounded below for normalized perturbations and has a finite number of negative modes. We prove that there is a negative mode for many gravitational instantons of the Hawking-Moss or ColemanendashDe Luccia type, and discuss the associated spectral flow. We also investigate Hawking-Turok constrained instantons, which occur in a generic inflationary model. Implementing the regularization and constraint proposed by Kirklin, Turok and Wiseman, we find that those instantons leading to substantial inflation do not possess negative modes. Using an alternate regularization and constraint motivated by reduction from five dimensions, we find a negative mode is present. These investigations shed new light on the suitability of Euclidean quantum gravity as a potential description of our universe

Homogeneous modes of cosmological instantons

Energy Technology Data Exchange (ETDEWEB)

Gratton, Steven; Turok, Neil

2001-06-15

We discuss the O(4) invariant perturbation modes of cosmological instantons. These modes are spatially homogeneous in Lorentzian spacetime and thus not relevant to density perturbations. But their properties are important in establishing the meaning of the Euclidean path integral. If negative modes are present, the Euclidean path integral is not well defined, but may nevertheless be useful in an approximate description of the decay of an unstable state. When gravitational dynamics is included, counting negative modes requires a careful treatment of the conformal factor problem. We demonstrate that for an appropriate choice of coordinate on phase space, the second order Euclidean action is bounded below for normalized perturbations and has a finite number of negative modes. We prove that there is a negative mode for many gravitational instantons of the Hawking-Moss or Coleman{endash}De Luccia type, and discuss the associated spectral flow. We also investigate Hawking-Turok constrained instantons, which occur in a generic inflationary model. Implementing the regularization and constraint proposed by Kirklin, Turok and Wiseman, we find that those instantons leading to substantial inflation do not possess negative modes. Using an alternate regularization and constraint motivated by reduction from five dimensions, we find a negative mode is present. These investigations shed new light on the suitability of Euclidean quantum gravity as a potential description of our universe.

Recent developments with CMOS SSPM photodetectors

Energy Technology Data Exchange (ETDEWEB)

Stapels, Christopher J. [Radiation Monitoring Devices, Inc., Watertown, MA (United States)], E-mail: CStapels@RMDInc.com; Barton, Paul [University of Michigan, Ann Arbor, MI (United States); Johnson, Erik B. [Radiation Monitoring Devices, Inc., Watertown, MA (United States); Wehe, David K. [University of Michigan, Ann Arbor, MI (United States); Dokhale, Purushottam; Shah, Kanai [Radiation Monitoring Devices, Inc., Watertown, MA (United States); Augustine, Frank L. [Augustine Engineering, Encinitas, CA (United States); Christian, James F. [Radiation Monitoring Devices, Inc., Watertown, MA (United States)

2009-10-21

Experiments and simulations using various solid-state photomultiplier (SSPM) designs have been performed to evaluate pixel layouts and explore design choices. SPICE simulations of a design for position-sensing SSPMs showed charge division in the resistor network, and anticipated timing performance of the device. The simulation results predict good position information for resistances in the range of 1-5 k{omega} and 150-{omega} preamplifier input impedance. Back-thinning of CMOS devices can possibly increase the fill factor to 100%, improve spectral sensitivity, and allow for the deposition of anti-reflective coatings after fabrication. We report initial results from back illuminating a CMOS SSPM, and single Geiger-mode avalanche photodiode (GPD) pixels, thinned to 50 {mu}m.

Few-mode erbium-doped fiber amplifier with photonic lantern for pump spatial mode control

NARCIS (Netherlands)

Lopez-Galmiche, G.; Eznaveh, Z. Sanjabi; Antonio-Lopez, J.E.; Benitez, A. M. Velazquez; Rodriguez-Asomoza, Jorge; Mondragon, J. J. Sanchez; Gonnet, C.; Sillard, P.; Li, G.; Schülzgen, A.; Okonkwo, C.M.; Amezcua Correa, R.

2016-01-01

We demonstrate a few-mode erbium-doped fiber amplifier employing a mode-selective photonic lantern for controlling the modal content of the pump light. Amplification of six spatial modes in a 5 m long erbium-doped fiber to x223C;6.2x2009;x2009;dBm average power is obtained while maintaining high

Path planning during combustion mode switch

Science.gov (United States)

Jiang, Li; Ravi, Nikhil

2015-12-29

Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.

Damping Measurements of Plasma Modes

Science.gov (United States)

Anderegg, F.; Affolter, M.; Driscoll, C. F.

2010-11-01

For azimuthally symmetric plasma modes in a magnesium ion plasma, confined in a 3 Tesla Penning-Malmberg trap with a density of n ˜10^7cm-3, we measure a damping rate of 2s-1plasma column, alters the frequency of the mode from 16 KHz to 192 KHz. The oscillatory fluid displacement is small compared to the wavelength of the mode; in contrast, the fluid velocity, δvf, can be large compared to v. The real part of the frequency satisfies a linear dispersion relation. In long thin plasmas (α> 10) these modes are Trivelpiece-Gould (TG) modes, and for smaller values of α they are Dubin spheroidal modes. However the damping appears to be non-linear; initially large waves have weaker exponential damping, which is not yet understood. Recent theoryootnotetextM.W. Anderson and T.M. O'Neil, Phys. Plasmas 14, 112110 (2007). calculates the damping of TG modes expected from viscosity due to ion-ion collisions; but the measured damping, while having a similar temperature and density dependence, is about 40 times larger than calculated. This discrepancy might be due to an external damping mechanism.

Mode division multiplexing over 19-cell hollow-core photonic bandgap fibre by employing integrated mode multiplexer

NARCIS (Netherlands)

Chen, H.; Uden, van R.G.H.; Okonkwo, C.M.; Jung, Y.; Wheeler, N.V.; Fokoua, E.N.; Baddela, N.; Petrovich, M.N.; Poletti, F.; Richardson, D.J.; Raz, O.; Waardt, de H.; Koonen, A.M.J.

2014-01-01

A photonic integrated mode coupler based on silicon-on-insulator is employed for mode division multiplexing (MDM) over a 193 m 19-cell hollow-core photonic bandgap fibre (HC-PBGF) with a -3 dB bandwidth >120 nm. Robust MDM transmissions using LP01 and LP11 modes, and two degenerate LP11 modes (LP11a

Experimental studies of tearing mode and resistive wall mode dynamics in the reversed field pinch configuration

International Nuclear Information System (INIS)

Malmberg, Jenny-Ann

2003-06-01

It is relatively straightforward to establish equilibrium in magnetically confined plasmas, but the plasma is frequently susceptible to a variety of instabilities that are driven by the free energy in the magnetic field or in the pressure gradient. These unstable modes exhibit effects that affect the particle, momentum and heat confinement properties of the configuration. Studies of the dynamics of several of the most important modes are the subject of this thesis. The studies are carried out on plasmas in the reversed field pinch (RFP) configuration. One phenomenon commonly observed in RFPs is mode wall locking. The localized nature of these phase- and wall locked structures results in localized power loads on the wall which are detrimental for confinement. A detailed study of the wall locked mode phenomenon is performed based on magnetic measurements from three RFP devices. The two possible mechanisms for wall locking are investigated. Locking as a result of tearing modes interacting with a static field error and locking due to the presence of a non-ideal boundary. The characteristics of the wall locked mode are qualitatively similar in a device with a conducting shell system (TPE-RX) compared to a device with a resistive shell (Extrap T2). A theoretical model is used for evaluating the threshold values for wall locking due to eddy currents in the vacuum vessel in these devices. A good correlation with experiment is observed for the conducting shell device. The possibility of successfully sustaining discharges in a resistive shell RFP is introduced in the recently rebuilt device Extrap T2R. Fast spontaneous mode rotation is observed, resulting in low magnetic fluctuations, low loop voltage and improved confinement. Wall locking is rarely observed. The low tearing mode amplitudes allow for the theoretically predicted internal non-resonant on-axis resistive wall modes to be observed. These modes have not previously been distinguished due to the formation of wall

ACCA College English Teaching Mode

Science.gov (United States)

Ding, Renlun

2008-01-01

This paper elucidates a new college English teaching mode--"ACCA" (Autonomous Cooperative Class-teaching All-round College English Teaching Mode). Integrated theories such as autonomous learning and cooperative learning into one teaching mode, "ACCA", which is being developed and advanced in practice as well, is the achievement…

Raman amplification of OAM modes

DEFF Research Database (Denmark)

Ingerslev, Kasper; Gregg, Patrick; Galili, Michael

2017-01-01

The set of fibre modes carrying orbital angular momentum (OAM) is a possible basis for mode division multiplexing. In this regard, fibres supporting OAM modes have been fabricated [1], and optical communication using these fibres, has been demonstrated [2]. A vital part of any long range...

Fluorescence quenching and the "ring-mode" to "red-mode" transition in alkali inductively coupled plasmas

Science.gov (United States)

Huang, M.; Bazurto, R.; Camparo, J.

2018-01-01

The ring-mode to red-mode transition in alkali metal inductively coupled plasmas (ICPs) (i.e., rf-discharge lamps) is perhaps the most important physical phenomenon affecting these devices as optical pumping light sources for atomic clocks and magnetometers. It sets the limit on useful ICP operating temperature, thereby setting a limit on ICP light output for atomic-clock/magnetometer signal generation, and it is a temperature region of ICP operation associated with discharge instability. Previous work has suggested that the mechanism driving the ring-mode to red-mode transition is associated with radiation trapping, but definitive experimental evidence validating that hypothesis has been lacking. Based on that hypothesis, one would predict that the introduction of an alkali-fluorescence quenching gas (i.e., N2) into the ICP would increase the ring-mode to red-mode transition temperature. Here, we test that prediction, finding direct evidence supporting the radiation-trapping hypothesis.

Beta limits in H-modes and VH-modes in JET

Energy Technology Data Exchange (ETDEWEB)

Smeulders, P; Hender, T C; Huysmans, G; Marcus, F; Ali-Arshad, S; Alper, B; Balet, B; Bures, M; Deliyanakis, N; Esch, H de; Fshpool, G; Jarvis, O N; Jones, T T.C.; Ketner, W; Koenig, R; Lawson, K; Lomas, P; O` Brien, D; Sadler, G; Stok, D; Stubberfield, P; Thomas, P; Thomen, K; Wesson, J [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Nave, M F [Universidade Tecnica, Lisbon (Portugal). Inst. Superior Tecnico

1994-07-01

In Hot-ion H- and VH-modes, the highest achieved beta was about 10% below the Troyon value in the best case of discharge 26087. The operational space of the high beta discharges obtained before March 1992 has been explored as function of the parameters H{sub ITER89P}, {beta}{sub n}, q{sub 95}, I{sub p}. Also, a limiting envelope on the fusion reactivity as a function of the average plasma pressure and beta has been observed with R{sub DD} related to {beta}{sub {phi}}{sup 2}.B{sub {phi}}{sup 4}. MHD stability analysis shows that the JET VH modes at the edge are in the second region for ballooning mode stability. The dependence of ballooning stability and the n=1 external kink on the edge current density is analyzed. (authors). 6 figs., 6 refs.

Study of complex modes

International Nuclear Information System (INIS)

Pastrnak, J.W.

1986-01-01

This eighteen-month study has been successful in providing the designer and analyst with qualitative guidelines on the occurrence of complex modes in the dynamics of linear structures, and also in developing computer codes for determining quantitatively which vibration modes are complex and to what degree. The presence of complex modes in a test structure has been verified. Finite element analysis of a structure with non-proportional dumping has been performed. A partial differential equation has been formed to eliminate possible modeling errors

Collective Lyapunov modes

International Nuclear Information System (INIS)

Takeuchi, Kazumasa A; Chaté, Hugues

2013-01-01

We show, using covariant Lyapunov vectors in addition to standard Lyapunov analysis, that there exists a set of collective Lyapunov modes in large chaotic systems exhibiting collective dynamics. Associated with delocalized Lyapunov vectors, they act collectively on the trajectory and hence characterize the instability of its collective dynamics. We further develop, for globally coupled systems, a connection between these collective modes and the Lyapunov modes in the corresponding Perron–Frobenius equation. We thereby address the fundamental question of the effective dimension of collective dynamics and discuss the extensivity of chaos in the presence of collective dynamics. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Lyapunov analysis: from dynamical systems theory to applications’. (paper)

Heart rate variability alters cardiac repolarization and electromechanical dynamics.

Science.gov (United States)

Phadumdeo, Vrishti M; Weinberg, Seth H

2018-04-07

Heart rate continuously varies due to autonomic regulation, stochasticity in pacemaking, and circadian rhythm, collectively termed heart rate variability (HRV), during normal physiological conditions. Low HRV is clinically associated with an elevated risk of cardiac arrhythmias. Alternans, a beat-to-beat alternation in action potential duration (APD) and/or intracellular calcium (Ca) transient, is a well-known risk factor associated with cardiac arrhythmias that is typically studied under conditions of a constant pacing rate, i.e., the absence of HRV. In this study, we investigate the effects of HRV on the interplay between APD, Ca, and electromechanical properties, employing a nonlinear discrete-time map model that governs APD and intracellular Ca cycling with a stochastic pacing period. We find that HRV can decrease variation in APD and peak Ca at fast pacing rates for which alternans is present. Further, increased HRV typically disrupts the alternating pattern for both APD and peak Ca and weakens the correlation between APD and peak Ca, thus decoupling Ca-mediated instabilities from repolarization alternation. We find that the efficacy of these effects is regulated by the sarcoplasmic reticulum Ca uptake rate. Overall, these results demonstrate that HRV disrupts arrhythmogenic alternans and suggests that HRV may be a significant factor in preventing life-threatening arrhythmias. Copyright © 2018 Elsevier Ltd. All rights reserved.

Relation between Working Memory Capacity and Auditory Stream Segregation in Children with Auditory Processing Disorder.

Science.gov (United States)

Lotfi, Yones; Mehrkian, Saiedeh; Moossavi, Abdollah; Zadeh, Soghrat Faghih; Sadjedi, Hamed

2016-03-01

This study assessed the relationship between working memory capacity and auditory stream segregation by using the concurrent minimum audible angle in children with a diagnosed auditory processing disorder (APD). The participants in this cross-sectional, comparative study were 20 typically developing children and 15 children with a diagnosed APD (age, 9-11 years) according to the subtests of multiple-processing auditory assessment. Auditory stream segregation was investigated using the concurrent minimum audible angle. Working memory capacity was evaluated using the non-word repetition and forward and backward digit span tasks. Nonparametric statistics were utilized to compare the between-group differences. The Pearson correlation was employed to measure the degree of association between working memory capacity and the localization tests between the 2 groups. The group with APD had significantly lower scores than did the typically developing subjects in auditory stream segregation and working memory capacity. There were significant negative correlations between working memory capacity and the concurrent minimum audible angle in the most frontal reference location (0° azimuth) and lower negative correlations in the most lateral reference location (60° azimuth) in the children with APD. The study revealed a relationship between working memory capacity and auditory stream segregation in children with APD. The research suggests that lower working memory capacity in children with APD may be the possible cause of the inability to segregate and group incoming information.

Verification of GENE and GYRO with L-mode and I-mode plasmas in Alcator C-Mod

Science.gov (United States)

Mikkelsen, D. R.; Howard, N. T.; White, A. E.; Creely, A. J.

2018-04-01

Verification comparisons are carried out for L-mode and I-mode plasma conditions in Alcator C-Mod. We compare linear and nonlinear ion-scale calculations by the gyrokinetic codes GENE and GYRO to each other and to the experimental power balance analysis. The two gyrokinetic codes' linear growth rates and real frequencies are in good agreement throughout all the ion temperature gradient mode branches and most of the trapped electron mode branches of the kyρs spectra at r/a = 0.65, 0.7, and 0.8. The shapes of the toroidal mode spectra of heat fluxes in nonlinear simulations are very similar for kyρs ≤ 0.5, but in most cases GENE has a relatively higher heat flux than GYRO at higher mode numbers. The ratio of ion to electron heat flux is similar in the two codes' simulations, but the heat fluxes themselves do not agree in almost all cases. In the I-mode regime, GENE's heat fluxes are ˜3 times those from GYRO, and they are ˜60%-100% higher than GYRO in the L-mode conditions. The GYRO under-prediction of Qe is much reduced in GENE's L-mode simulations, and it is eliminated in the I-mode simulations. This largely improved agreement with the experimental electron heat flux is offset, however, by the large overshoot of GENE's ion heat fluxes, which are 2-3 times the experimental level, and its electron heat flux overshoot at r/a = 0.80 in the I-mode. Rotation effects can explain part of the difference between the two codes' predictions, but very significant differences remain in simulations without any rotation effects.

Interaction of tearing modes

International Nuclear Information System (INIS)

Satya, Y.; Schmidt, G.

1979-01-01

A fully developed tearing mode modifies the magnetic field profile. The effect of this profile modification on the linear growth rate of a different tearing mode in a slab and cylindrical geometry is investigated

Fluxon modes in superconducting multilayers

DEFF Research Database (Denmark)

Pedersen, Niels Falsig; Madsen, Søren Peder

2004-01-01

We show how to construct fluxon modes from plasma modes in the inductively coupled stacked Josephson junctions, and consider some special cases of these fluxon modes analytically. In some cases we can find exact analytical solutions when we choose the bias current in a special way. We also consid...

Group schema therapy versus group cognitive behavioral therapy for social anxiety disorder with comorbid avoidant personality disorder: study protocol for a randomized controlled trial.

Science.gov (United States)

Baljé, Astrid; Greeven, Anja; van Giezen, Anne; Korrelboom, Kees; Arntz, Arnoud; Spinhoven, Philip

2016-10-08

Social anxiety disorder (SAD) with comorbid avoidant personality disorder (APD) has a high prevalence and is associated with serious psychosocial problems and high societal costs. When patients suffer from both SAD and APD, the Dutch multidisciplinary guidelines for personality disorders advise offering prolonged cognitive behavioral therapy (CBT). Recently there is increasing evidence for the effectiveness of schema therapy (ST) for personality disorders such as borderline personality disorder and cluster C personality disorders. Since ST addresses underlying personality characteristics and maladaptive coping strategies developed in childhood, this treatment might be particularly effective for patients with SAD and comorbid APD. To our knowledge, there are no studies comparing CBT with ST in this particular group of patients. This superiority trial aims at comparing the effectiveness of these treatments. As an additional goal, predictors and underlying mechanisms of change will be explored. The design of the study is a multicentre two-group randomized controlled trial (RCT) in which the treatment effect of group cognitive behavioral therapy (GCBT) will be compared to that of group schema therapy (GST) in a semi-open group format. A total of 128 patients aged 18-65 years old will be enrolled. Patients will receive 30 sessions of GCBT or GST during a period of approximately 9 months. Primary outcome measures are the Liebowitz Social Anxiety Scale Self-Report (LSAS-SR) for social anxiety disorder and the newly developed Avoidant Personality Disorder Severity Index (AVPDSI) for avoidant personality disorder. Secondary outcome measures are the MINI section SAD, the SCID-II section APD, the Schema Mode Inventory (SMI-2), the Inventory of Depressive Symptomatology Self-Report (IDS-SR), the World Health Organization Quality of Life-BREF (WHOQOL-BREF), the Difficulties in Emotion Regulation Scale (DERS), the Rosenberg Self-Esteem Scale (RSES) and the Acceptance and Action

The energy spectrum of electromagnetic normal modes in dissipative media: modes between two metal half spaces

International Nuclear Information System (INIS)

Sernelius, Bo E

2008-01-01

The energy spectrum of electromagnetic normal modes plays a central role in the theory of the van der Waals and Casimir interaction. Here we study the modes in connection with the van der Waals interaction between two metal half spaces. Neglecting dissipation leads to distinct normal modes with real-valued frequencies. Including dissipation seems to have the effect that these distinct modes move away from the real axis into the complex frequency plane. The summation of the zero-point energies of these modes render a complex-valued result. Using the contour integration, resulting from the use of the generalized argument principle, gives a real-valued and different result. We resolve this contradiction and show that the spectrum of true normal modes forms a continuum with real frequencies

Mode coupling in spin torque oscillators

International Nuclear Information System (INIS)

Zhang, Steven S.-L.; Zhou, Yan; Li, Dong; Heinonen, Olle

2016-01-01

A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.

Theory of tokamak resistive fishbone modes

International Nuclear Information System (INIS)

Shi Bingren; Sui Guofang

1995-12-01

A special kind of internal kink mode, the fishbone, can be excited by the energetic particles in tokamak plasmas. Theoretical analyses of fishbone modes based on the ideal MHD framework have predicted that two branches of modes exists. One is the Chen-White branch with ω∼ω-bar dm , corresponding to a higher threshold in β h ; the other is the Coppis branch with ω∼ω *i , and a much lower threshold in β h . The latter mode would put a rather unfavourable restriction on heating efficiency and on plasma confinement. However. It is found that the resistivity effect is essential for this mode. In this paper, a new resistive fishbone mode analysis is carried out. In the (γ mhd ,β H ) space, the stability diagram shows complicate structure, the Coppis branch is replaced by a weakly unstable mode and there is no longer closed stable region. The growth rate of this mode varies with β h , its peak value is still very low compared to other internal modes. The implications of these results to future tokamak experiments are discussed. (8 figs.)

Mode coupling in spin torque oscillators

Energy Technology Data Exchange (ETDEWEB)

Zhang, Steven S.-L., E-mail: ZhangShule@missouri.edu [Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211 (United States); Zhou, Yan, E-mail: yanzhou@hku.hk [Department of Physics, The University of Hong Kong, Hong Kong (China); Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong (China); Li, Dong, E-mail: geodesic.ld@gmail.com [Department of Physics, Centre for Nonlinear Studies, and Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems, Hong Kong Baptist University, Kowloon Tong, Hong Kong (China); Heinonen, Olle, E-mail: heinonen@anl.gov [Material Science Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Northwestern-Argonne Institute of Science and Technology, 2145 Sheridan Road, Evanston, IL 60208 (United States); Computation Institute, The Unversity of Chicago, 5735 S Ellis Avenue, Chicago, IL 60637 (United States)

2016-09-15

A number of recent experimental works have shown that the dynamics of a single spin torque oscillator can exhibit complex behavior that stems from interactions between two or more modes of the oscillator, such as observed mode-hopping or mode coexistence. There has been some initial work indicating how the theory for a single-mode (macro-spin) spin torque oscillator should be generalized to include several modes and the interactions between them. In the present work, we rigorously derive such a theory starting with the Landau–Lifshitz–Gilbert equation for magnetization dynamics by expanding up to third-order terms in deviation from equilibrium. Our results show how a linear mode coupling, which is necessary for observed mode-hopping to occur, arises through coupling to a magnon bath. The acquired temperature dependence of this coupling implies that the manifold of orbits and fixed points may shift with temperature. - Highlights: • Deriving equations for coupled modes in spin torque oscillators. • Including Hamiltonian formalism and elimination of three–magnon processes. • Thermal bath of magnons central to mode coupling. • Numerical examples of circular and elliptical devices.

Probable mode prediction for H.264 advanced video coding P slices using removable SKIP mode distortion estimation

Science.gov (United States)

You, Jongmin; Jeong, Jechang

2010-02-01

The H.264/AVC (advanced video coding) is used in a wide variety of applications including digital broadcasting and mobile applications, because of its high compression efficiency. The variable block mode scheme in H.264/AVC contributes much to its high compression efficiency but causes a selection problem. In general, rate-distortion optimization (RDO) is the optimal mode selection strategy, but it is computationally intensive. For this reason, the H.264/AVC encoder requires a fast mode selection algorithm for use in applications that require low-power and real-time processing. A probable mode prediction algorithm for the H.264/AVC encoder is proposed. To reduce the computational complexity of RDO, the proposed method selects probable modes among all allowed block modes using removable SKIP mode distortion estimation. Removable SKIP mode distortion is used to estimate whether or not a further divided block mode is appropriate for a macroblock. It is calculated using a no-motion reference block with a few computations. Then the proposed method reduces complexity by performing the RDO process only for probable modes. Experimental results show that the proposed algorithm can reduce encoding time by an average of 55.22% without significant visual quality degradation and increased bit rate.

A new programmable zone dosimeter for operational monitoring and measurement of external gamma radiation

International Nuclear Information System (INIS)

Toledo Acosta, Rene; Arteche Diaz, Raul; Mesa Perez, Guillermo; Fernandez Llanez, Sandra; Tamayo Garcia, Jose Antonio; Alonso Villanueva, Gilberto

2010-01-01

The detection and the measurement of the nuclear radiations have turn into an important item in the nuclear detectors application and specifically the Geiger Muller ones. Coming from theirs high detection sensibility, robust construction and relative simplicity of the associated circuit, the Geiger Tubes are still one of the most widely used detectors in all the application areas regarding physics and nuclear investigations A new design instrument is presented to be measures the ambient dose of external (gamma) radiation since 10 mSv/h. It consists of three elements: Geiger-Muller detector, the electronic board for the acquisition and control and the application software. The instrument communicates trough a USB interface to the Personal Computer only for adjust calibration parameters. The software was developed in the C programming language using PICC4, 08 compilers. (author)

Fused-fiber-based 3-dB mode insensitive power splitters for few-mode optical fiber networks

Science.gov (United States)

Ren, Fang; Huang, Xiaoshan; Wang, Jianping

2017-11-01

We propose a 3-dB mode insensitive power splitter (MIPS) capable of broadcasting and combining optical signals. It is fabricated with two identical few-mode fibers (FMFs) by a heating and pulling technique. The mode-dependent power transfer characteristic as a function of pulling length is investigated. For exploiting its application, we experimentally demonstrate both FMF-based transmissive and reflective star couplers consisting of multiple 3-dB mode insensitive power splitters, which perform broadcasting and routing signals in few-mode optical fiber networks such as mode-division multiplexing (MDM) local area networks using star topology. For experimental demonstration, optical on-off keying signals at 10 Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. Measured bit error ratio results show reasonable power penalties. It is found that a reflective star coupler in MDM networks can reduce half of the total amount of required fibers comparing to that of a transmissive star coupler. This MIPS is more efficient, more reliable, more flexible, and more cost-effective for future expansion and application in few-mode optical fiber networks.

Switch mode power supply

International Nuclear Information System (INIS)

Kim, Hui Jun

1993-06-01

This book concentrates on switch mode power supply. It has four parts, which are introduction of switch mode power supply with DC-DC converter such as Buck converter boost converter, Buck-boost converter and PWM control circuit, explanation for SMPS with DC-DC converter modeling and power mode control, resonance converter like resonance switch, converter, multi resonance converter and series resonance and parallel resonance converters, basic test of SMPS with PWM control circuit, Buck converter, Boost converter, flyback converter, forward converter and IC for control circuit.

Nonlinear surface elastic modes in crystals

Science.gov (United States)

Gorentsveig, V. I.; Kivshar, Yu. S.; Kosevich, A. M.; Syrkin, E. S.

1990-03-01

The influence of nonlinearity on shear horizontal surface elastic waves in crystals is described on the basis of the effective nonlinear Schrödinger equation. It is shown that the corresponding solutions form a set of surface modes and the simplest mode coincides with the solution proposed by Mozhaev. The higher order modes have internal frequencies caused by the nonlinearity. All these modes decay in the crystal as uoexp(- z/ zo) atz≫ zo- u o-1 ( z is the distance from the crystal surface, uo the wave amplitude at the surface). The creation of the modes from a localized surface excitation has a threshold. The stability of the modes is discussed.

Mixed-Mode Crack Growth in Wood

Directory of Open Access Journals (Sweden)

Octavian POP

2012-09-01

Full Text Available In timber elements the mixed mode dependsessentially of wood anatomy and load configuration.In these conditions, in order to evaluate the materialbehavior and the fracture process, it’s necessary toseparate the part of each mode. The mixed modeseparation allows evaluating the amplitude offracture mode. In the present paper, using a mixedmodecrack growth specimen made in Douglas fir,the mixed mode crack growth process is studythanks to marks tracking method. Using the markstracking method the characteristic displacementsassociated to opening and shear mode aremeasured. From the experimental measurements,the energy release rate associated to opening andshear modes is calculated into to account the crackadvancement during the test.

Foreign direct investment mode choice : entry and establishment modes in transition economies

NARCIS (Netherlands)

Dikova, Desislava; van Witteloostuijn, Arien

In this study, we bridge two streams of foreign direct investment literature, specifically studies on establishment mode choice (i.e., the choice between an acquisition and a greenfield establishment) and studies on entry mode choice (i.e., the choice between a wholly owned outlet and a subsidiary

Investigation of single-mode and multi-mode hydromagnetic Rayleigh-Taylor instability in planar geometry

International Nuclear Information System (INIS)

Roderick, N.F.; Cochrane, K.; Douglas, M.R.

1998-01-01

Previous investigations carried out to study various methods of seeding the hydromagnetic Rayleigh-Taylor instability in magnetohydrodynamic simulations showed features similar to those seen in hydrodynamic calculations. For periodic single-mode initiations the results showed the appearance of harmonics as the single modes became nonlinear. For periodic multi-mode initiations new modes developed that indicated the presence of mode coupling. The MHD simulations used parameters of the high velocity large radius z-pinch experiments performed in the Z-accelerator at Sandia National Laboratories. The cylindrical convergent geometry and variable acceleration of these configurations made comparison with analytic, developed for planar geometry with constant acceleration, difficult. A set of calculations in planar geometry using constant current to produce acceleration and parameters characteristic of the cylindrical implosions has been performed to allow a better comparison. Results of these calculations, comparison with analytic theory, and comparison with the cylindrical configuration calculations will be discussed

Zero modes and entanglement entropy

Energy Technology Data Exchange (ETDEWEB)

Yazdi, Yasaman K. [Perimeter Institute for Theoretical Physics,31 Caroline St. N., Waterloo, ON, N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo,200 University Avenue West, Waterloo, ON, N2L 3G1 (Canada)

2017-04-26

Ultraviolet divergences are widely discussed in studies of entanglement entropy. Also present, but much less understood, are infrared divergences due to zero modes in the field theory. In this note, we discuss the importance of carefully handling zero modes in entanglement entropy. We give an explicit example for a chain of harmonic oscillators in 1D, where a mass regulator is necessary to avoid an infrared divergence due to a zero mode. We also comment on a surprising contribution of the zero mode to the UV-scaling of the entanglement entropy.

Mode Combinations and International Operations

DEFF Research Database (Denmark)

Benito, Gabriel R. G.; Petersen, Bent; Welch, Lawrence S.

2011-01-01

reveals that companies tend to combine modes of operation; thereby producing unique foreign operation mode “packages” for given activities and/or countries, and that the packages are liable to be modified over time – providing a potentially important optional path for international expansion. Our data...... key markets (China, UK and USA) as the basis for an exploration of the extent to which, and how and why, companies combine clearly different foreign operation modes. We examine their use of foreign operation mode combinations within given value activities as well as within given countries. The study...

Standardization of Keyword Search Mode

Science.gov (United States)

Su, Di

2010-01-01

In spite of its popularity, keyword search mode has not been standardized. Though information professionals are quick to adapt to various presentations of keyword search mode, novice end-users may find keyword search confusing. This article compares keyword search mode in some major reference databases and calls for standardization. (Contains 3…

The quiescent H-mode regime for high performance edge localized mode-stable operation in future burning plasmas

Energy Technology Data Exchange (ETDEWEB)

Garofalo, A. M., E-mail: garofalo@fusion.gat.com; Burrell, K. H.; Meneghini, O.; Osborne, T. H.; Paz-Soldan, C.; Smith, S. P.; Snyder, P. B.; Turnbull, A. D. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Eldon, D.; Grierson, B. A.; Solomon, W. M. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Hanson, J. M. [Columbia University, 2960 Broadway, New York, New York 10027-6900 (United States); Holland, C. [University of California San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Huijsmans, G. T. A.; Liu, F.; Loarte, A. [ITER Organization, Route de Vinon sur Verdon, 13067 St Paul Lez Durance (France); Zeng, L. [University of California Los Angeles, P.O. Box 957099, Los Angeles, California 90095-7099 (United States)

2015-05-15

For the first time, DIII-D experiments have achieved stationary quiescent H-mode (QH-mode) operation for many energy confinement times at simultaneous ITER-relevant values of beta, confinement, and safety factor, in an ITER-like shape. QH-mode provides excellent energy confinement, even at very low plasma rotation, while operating without edge localized modes (ELMs) and with strong impurity transport via the benign edge harmonic oscillation (EHO). By tailoring the plasma shape to improve the edge stability, the QH-mode operating space has also been extended to densities exceeding 80% of the Greenwald limit, overcoming the long-standing low-density limit of QH-mode operation. In the theory, the density range over which the plasma encounters the kink-peeling boundary widens as the plasma cross-section shaping is increased, thus increasing the QH-mode density threshold. The DIII-D results are in excellent agreement with these predictions, and nonlinear magnetohydrodynamic analysis of reconstructed QH-mode equilibria shows unstable low n kink-peeling modes growing to a saturated level, consistent with the theoretical picture of the EHO. Furthermore, high density operation in the QH-mode regime has opened a path to a new, previously predicted region of parameter space, named “Super H-mode” because it is characterized by very high pedestals that can be more than a factor of two above the peeling-ballooning stability limit for similar ELMing H-mode discharges at the same density.

2-LP mode few-mode fiber amplifier employing ring-core erbium-doped fiber.

Science.gov (United States)

Ono, Hirotaka; Hosokawa, Tsukasa; Ichii, Kentaro; Matsuo, Shoichiro; Nasu, Hitoshi; Yamada, Makoto

2015-10-19

A fiber amplifier supporting 2 LP modes that employs a ring-core erbium-doped fiber (RC-EDF) is investigated to reduce differential modal gain (DMG). The inner and outer radii of the ring-core of the RC-EDF are clarified for 2-LP mode operation of the amplifier, and are optimized to reduce the DMG. It is shown that using the overlap integral between the erbium-doped core area and the signal power mode distribution is a good way to optimize the inner and outer radii of the ring-core of the RC-EDF and thus minimize the DMG. A fabricated RC-EDF and a constructed 2-LP mode EDFA are described and a small DMG of around 1 dB is realized for LP01, LP11 and LP21 pumping.

Preconditioned dynamic mode decomposition and mode selection algorithms for large datasets using incremental proper orthogonal decomposition

Science.gov (United States)

Ohmichi, Yuya

2017-07-01

In this letter, we propose a simple and efficient framework of dynamic mode decomposition (DMD) and mode selection for large datasets. The proposed framework explicitly introduces a preconditioning step using an incremental proper orthogonal decomposition (POD) to DMD and mode selection algorithms. By performing the preconditioning step, the DMD and mode selection can be performed with low memory consumption and therefore can be applied to large datasets. Additionally, we propose a simple mode selection algorithm based on a greedy method. The proposed framework is applied to the analysis of three-dimensional flow around a circular cylinder.

New Very Low Noise Multilayer And Graded-Gap Avalanche Photodiodes For The 0.8 To 1 .8 μm Wavelength Region

Science.gov (United States)

Capasso, F.; Tsang, W. T.; Williams, G. F.

1982-12-01

Recent experimental and theoretical results on a new class of low noise avalanche photo-diodes are reviewed. A large enhancement of the impact ionization rates ratio (a/(3=10) has been demonstrated in AlGaAs/GaAs superlattices and graded band gap detector structures. In addition two novel photodiodes ("staircase" and "channeling" APDs) where only electrons multiply, have been proposed. The staircase APD is the solid state analog of the photo-multiplier with discrete dynodes. It has a low operating voltage (5-20 volts) and a lower excess noise factor, in the ideal case, than that of an ideal conventional APD The channeling APD is instead the solid state analog of a channeltron photomultiplier and has the unique feature of an ultrahigh a/β, ratio (≍∞) compatible with high gain (>100).

Safety analysis for push-mode and rotary-mode core sampling

International Nuclear Information System (INIS)

Milliken, N.J.; Geschke, G.R.

1995-01-01

This safety analysis analyzes using the push-mode core sampling truck in the push-mode and the rotary-mode core sampling trucks in both the push- and rotary-modes to retrieve core samples that, once taken and analyzed, will yield waste characterization data for the hazardous waste tanks at the Hanford Site. Operation of the core sampling trucks in both the push- and rotary-modes was reviewed to determine whether the release of radioactive materials could occur during operation. It was concluded that there are three credible scenarios: a sample spill outside of the tank, a steam release event, and an unfiltered release to the environment during continuous exhauster operation. The probability of a sample spill was found to be 10 -4 /event, the probability of a steam release event was determined to fall in the unlikely range (10 -2 /event to 10 -4 /event), and the probability of an unfiltered release was calculated to be 5 x 10 -3 /year. Typically, events with probabilities of 10 -6 /event or less are not considered to be risk significant, and the consequences usually are not analyzed. The three accident scenarios were analyzed to calculate the dose consequences. It was determined that the steam release event is the bounding accident. The onsite and offsite dose consequences for this event are calculated to be 0.24 Sv (24 rem) and 3.2 x 10 -4 Sv (32 mrem), respectively. These consequences are below the risk acceptance guidelines for an unlikely event, as established in WHC-CM-4-46, Nonreactor Facility Safety Analysis Manual. With the design features and the use of the controls presented in Section 8.0, this operation represents a minimal risk

Higher Order Mode Fibers

DEFF Research Database (Denmark)

Israelsen, Stine Møller

This PhD thesis considers higher order modes (HOMs) in optical fibers. That includes their excitation and characteristics. Within the last decades, HOMs have been applied both for space multiplexing in optical communications, group velocity dispersion management and sensing among others......-radial polarization as opposed to the linear polarization of the LP0X modes. The effect is investigated numerically in a double cladding fiber with an outer aircladding using a full vectorial modesolver. Experimentally, the bowtie modes are excited using a long period grating and their free space characteristics...... and polarization state are investigated. For this fiber, the onset of the bowtie effect is shown numerically to be LP011. The characteristics usually associated with Bessel-likes modes such as long diffraction free length and selfhealing are shown to be conserved despite the lack of azimuthal symmetry...

Exploiting selective excitation of strongly coupled modes to reduce DMGD in multi-mode transmission systems

NARCIS (Netherlands)

van Weerdenburg, J.J.A.; Antonio-Lopez, J.E.; Alvarado-Zacarias, J.; Molin, D.; Bigot-Astruc, M.; van Uden, R.; de Waardt, H.; Koonen, A.M.J.; Amezcua-Correa, R.; Sillard, P.; Okonkwo, C.M.

2016-01-01

By exploiting strong coupling in higher-order modes, we experimentally demonstrate reduced differential mode group delay by a factor of 3. Comparing LP02+LP21 with respect to LP01+LP11 3-mode transmission, a 27% reduction in equalizer length is shown after 53.4km MMF transmission.

SEARCH FOR GLOBAL f-MODES AND p-MODES IN THE {sup 8}B NEUTRINO FLUX

Energy Technology Data Exchange (ETDEWEB)

Lopes, Ilídio, E-mail: ilidio.lopes@ist.utl.pt, E-mail: ilopes@uevora.pt [Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Departamento de Física, Escola de Ciências e Tecnologia, Universidade de Évora, Colégio Luis António Verney, 7002-554 Évora (Portugal)

2013-11-01

The impact of global acoustic modes on the {sup 8}B neutrino flux time series is computed for the first time. It is shown that the time fluctuations of the {sup 8}B neutrino flux depend on the amplitude of acoustic eigenfunctions in the region where the {sup 8}B neutrino flux is produced: modes with low n (or order) that have eigenfunctions with a relatively large amplitude in the Sun's core strongly affect the neutrino flux; conversely, modes with high n that have eigenfunctions with a minimal amplitude in the Sun's core have a very small impact on the neutrino flux. It was found that the global modes with a larger impact on the {sup 8}B neutrino flux have a frequency of oscillation in the interval 250 μHz to 500 μHz (or a period in the interval 30 minutes to 70 minutes), such as the f-modes (n = 0) for the low degrees, radial modes of order n ≤ 3, and the dipole mode of order n = 1. Their corresponding neutrino eigenfunctions are very sensitive to the solar inner core and are unaffected by the variability of the external layers of the solar surface. If time variability of neutrinos is observed for these modes, it will lead to new ways of improving the sound speed profile inversion in the central region of the Sun.

A design of a mode converter for electron cyclotron heating by the method of normal mode expansion

International Nuclear Information System (INIS)

Hoshino, Katsumichi; Kawashima, Hisato; Hata, Kenichiro; Yamamoto, Takumi

1983-09-01

Mode conversion of electromagnetic wave propagating in the over-size circular waveguide is attained by giving a periodical perturbation in the guide wall. Mode coupling equation is expressed by ''generalized telegraphist's equations'' which are derived from the Maxwell's equations using a normal mode expansion. A computer code to solve the coupling equations is developed and mode amplitude, conversion efficiency, etc. of a particular type of mode converter for the 60 GHz electron cyclotron heating are obtained. (author)

Surface modes in physics

CERN Document Server

Sernelius, Bo E

2011-01-01

Electromagnetic surface modes are present at all surfaces and interfaces between material of different dielectric properties. These modes have very important effects on numerous physical quantities: adhesion, capillary force, step formation and crystal growth, the Casimir effect etc. They cause surface tension and wetting and they give rise to forces which are important e.g. for the stability of colloids.This book is a useful and elegant approach to the topic, showing how the concept of electromagnetic modes can be developed as a unifying theme for a range of condensed matter physics. The

Detecting mode hopping in single-longitudinal-mode fiber ring lasers based on an unbalanced fiber Michelson interferometer.

Science.gov (United States)

Ma, Mingxiang; Hu, Zhengliang; Xu, Pan; Wang, Wei; Hu, Yongming

2012-10-20

A method of detecting mode hopping for single-longitudinal-mode (SLM) fiber ring lasers has been proposed and experimentally demonstrated. The method that is based on an unbalanced Michelson interferometer (MI) utilizing phase generated carrier modulation instantly transforms mode-hopping dynamics into steep phase changes of the interferometer. Multiform mode hops in an SLM erbium-doped fiber ring laser with an 18.6 MHz mode spacing have been detected exactly in real-time domain and discussed in detail. Numerical results show that the MI-based method has a high testing sensitivity for identifying mode hopping, which will play a significant role in evaluating the output stability of SLM fiber lasers.

Overlap relation between free-space Laguerre Gaussian modes and step-index fiber modes

CSIR Research Space (South Africa)

Bruning, R

2015-09-01

Full Text Available to control the optical proper- ties of the emerging beam or the excited field distributions at the fiber input. The simplest connection is given by fibers with an parabolic refractive index profile, typical of graded-index fibers, whose modes can be described..., in general free space modes are not suitable to excite selective pure fiber modes and additional beam shaping techniques are required, such as the use of computer generated holograms [5]. The main disadvan- tages of such beam shaping techniques are the low...

Few-mode vertical-cavity surface-emitting laser: Optional emission of transverse modes with different polarizations

Science.gov (United States)

Zhong, Chuyu; Zhang, Xing; Hofmann, Werner; Yu, Lijuan; Liu, Jianguo; Ning, Yongqiang; Wang, Lijun

2018-05-01

Few-mode vertical-cavity surface-emitting lasers that can be controlled to emit certain modes and polarization states simply by changing the biased contacts are proposed and fabricated. By directly etching trenches in the p-doped distributed Bragg reflector, the upper mesa is separated into several submesas above the oxide layer. Individual contacts are then deposited. Each contact is used to control certain transverse modes with different polarization directions emitted from the corresponding submesa. These new devices can be seen as a prototype of compact laser sources in mode division multiplexing communications systems.

Mode Equivalence of Health Indicators Between Data Collection Modes and Mixed-Mode Survey Designs in Population-Based Health Interview Surveys for Children and Adolescents: Methodological Study.

Science.gov (United States)

Mauz, Elvira; Hoffmann, Robert; Houben, Robin; Krause, Laura; Kamtsiuris, Panagiotis; Gößwald, Antje

2018-03-05

The implementation of an Internet option in an existing public health interview survey using a mixed-mode design is attractive because of lower costs and faster data availability. Additionally, mixed-mode surveys can increase response rates and improve sample composition. However, mixed-mode designs can increase the risk of measurement error (mode effects). This study aimed to determine whether the prevalence rates or mean values of self- and parent-reported health indicators for children and adolescents aged 0-17 years differ between self-administered paper-based questionnaires (SAQ-paper) and self-administered Web-based questionnaires (SAQ-Web), as well as between a single-mode control group and different mixed-mode groups. Data were collected for a methodological pilot of the third wave of the "German Health Interview and Examination Survey for Children and Adolescents". Questionnaires were completed by parents or adolescents. A population-based sample of 11,140 children and adolescents aged 0-17 years was randomly allocated to 4 survey designs-a single-mode control group with paper-and-pencil questionnaires only (n=970 parents, n=343 adolescents)-and 3 mixed-mode designs, all of which offered Web-based questionnaire options. In the concurrent mixed-mode design, both questionnaires were offered at the same time (n=946 parents, n=290 adolescents); in the sequential mixed-mode design, the SAQ-Web was sent first, followed by the paper questionnaire along with a reminder (n=854 parents, n=269 adolescents); and in the preselect mixed-mode design, both options were offered and the respondents were asked to request the desired type of questionnaire (n=698 parents, n=292 adolescents). In total, 3468 questionnaires of parents of children aged 0-17 years (SAQ-Web: n=708; SAQ-paper: n=2760) and 1194 questionnaires of adolescents aged 11-17 years (SAQ-Web: n=299; SAQ-paper: n=895) were analyzed. Sociodemographic characteristics and a broad range of health indicators for

Challenges in higher order mode Raman amplifiers

DEFF Research Database (Denmark)

Rottwitt, Karsten; Nielsen, Kristian; Friis, Søren Michael Mørk

2015-01-01

A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed......A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed...

High degree modes and instrumental effects

Energy Technology Data Exchange (ETDEWEB)

Korzennik, S G [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Rabello-Soares, M C; Schou, J [Stanford University, Stanford, CA (United States)], E-mail: skorzennik@cfa.harvard.edu

2008-10-15

Full-disk observations taken with the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO) spacecraft, or the upgraded Global Oscillations Network Group (GONG) instruments, have enough spatial resolution to resolve modes up to {iota} = 1000 if not {iota} = 1500. The inclusion of such high-degree modes (i.e., {iota} {<=} 1000) improves dramatically inferences near the surface. Unfortunately, observational and instrumental effects cause the characterization of high degree modes to be quite complicated. Indeed, the characteristics of the solar acoustic spectrum are such that, for a given order, mode lifetimes get shorter and spatial leaks get closer in frequency as the degree of a mode increases. A direct consequence of this property is that individual modes are resolved only at low and intermediate degrees. At high degrees the individual modes blend into ridges and the power distribution of the ridge defines the ridge central frequency, masking the underlying mode frequency. An accurate model of the amplitude of the peaks that contribute to the ridge power distribution is needed to recover the underlying mode frequency from fitting the ridge. We present a detailed discussion of the modeling of the ridge power distribution, and the contribution of the various observational and instrumental effects on the spatial leakage, in the context of the MDI instrument. We have constructed a physically motivated model (rather than an ad hoc correction scheme) that results in a methodology that can produce unbiased estimates of high-degree modes. This requires that the instrumental characteristics are well understood, a task that has turned out to pose a major challenge. We also present our latest results, where most of the known instrumental and observational effects that affect specifically high-degree modes were removed. These new results allow us to focus our attention on changes with solar activity. Finally, we present variations of mode

Mode Combinations and International Operations

DEFF Research Database (Denmark)

Benito, Gabriel R. G.; Petersen, Bent; Welch, Lawrence S.

2011-01-01

reveals that companies tend to combine modes of operation; thereby producing unique foreign operation mode “packages” for given activities and/or countries, and that the packages are liable to be modified over time—providing a potentially important optional path for international expansion. The data show...... markets (China, UK and USA) is used as the basis for an exploration of the extent to which, and how and why, companies combine clearly different foreign operation modes. We examine their use of foreign operation mode combinations within given value activities as well as within given countries. The study...

A Current-Mode Common-Mode Feedback Circuit (CMFB) with Rail-to-Rail Operation

Science.gov (United States)

Suadet, Apirak; Kasemsuwan, Varakorn

2011-03-01

This paper presents a current-mode common-mode feedback (CMFB) circuit with rail-to-rail operation. The CMFB is a stand-alone circuit, which can be connected to any low voltage transconductor without changing or upsetting the existing circuit. The proposed CMFB employs current mirrors, operating as common-mode detector and current amplifier to enhance the loop gain of the CMFB. The circuit employs positive feedback to enhance the output impedance and gain. The circuit has been designed using a 0.18 μm CMOS technology under 1V supply and analyzed using HSPICE with BSIM3V3 device models. A pseudo-differential amplifier using two common sources and the proposed CMFB shows rail to rail output swing (± 0.7 V) with low common-mode gain (-36 dB) and power dissipation of 390 μW.

Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H-mode

International Nuclear Information System (INIS)

Baumgaertel J.A., Redi M.H., Budny R.V., Rewoldt G., Dorland W.

2005-01-01

Insight into plasma microturbulence and transport is being sought using linear simulations of drift waves on the National Spherical Torus Experiment (NSTX), following a study of drift wave modes on the Alcator C-Mod Tokamak. Microturbulence is likely generated by instabilities of drift waves, which cause transport of heat and particles. Understanding this transport is important because the containment of heat and particles is required for the achievement of practical nuclear fusion. Microtearing modes may cause high heat transport through high electron thermal conductivity. It is hoped that microtearing will be stable along with good electron transport in the proposed low collisionality International Thermonuclear Experimental Reactor (ITER). Stability of the microtearing mode is investigated for conditions at mid-radius in a high density NSTX high performance (H-mode) plasma, which is compared to the proposed ITER plasmas. The microtearing mode is driven by the electron temperature gradient, and believed to be mediated by ion collisions and magnetic shear. Calculations are based on input files produced by TRXPL following TRANSP (a time-dependent transport analysis code) analysis. The variability of unstable mode growth rates is examined as a function of ion and electron collisionalities using the parallel gyrokinetic computational code GS2. Results show the microtearing mode stability dependence for a range of plasma collisionalities. Computation verifies analytic predictions that higher collisionalities than in the NSTX experiment increase microtearing instability growth rates, but that the modes are stabilized at the highest values. There is a transition of the dominant mode in the collisionality scan to ion temperature gradient character at both high and low collisionalities. The calculations suggest that plasma electron thermal confinement may be greatly improved in the low-collisionality ITER

Differential effects of thioridazine enantiomers on action potential duration in rabbit papillary muscle

DEFF Research Database (Denmark)

Jensen, Ask Schou; Pennisi, Cristian Pablo; Sevcencu, Cristian

2015-01-01

with (+)-thioridazine. In this study we for the first time investigate the cardiotoxicity of the isolated thioridazine enantiomers and show their effects on ventricular repolarization. The effects of (+)-thioridazine, (-)-thioridazine, and racemate on the rabbit ventricular action potential duration (APD) were...... investigated in a randomized controlled blinded experiment. Action potentials were measured in papillary muscles isolated from 21 female rabbits, and the drug effect on 90% APD in comparison with control (DeltaDelta-APD90) was evaluated. Increasing concentrations of (+)-thioridazine and the racemate caused...

Flecainide attenuates rate adaptation of ventricular repolarization in guinea-pig heart

DEFF Research Database (Denmark)

Osadchii, Oleg E.

2016-01-01

examined flecainide effect on adaptation of the QT interval and ventricular action potential duration (APD) to abrupt reductions of the cardiac cycle length. DESIGN: ECG and ventricular epicardial and endocardial monophasic APD were recorded in isolated, perfused guinea-pig heart preparations upon...... a sustained cardiac acceleration (rapid pacing for 30 s), and following a single perturbation of the cycle length evoked by extrasystolic stimulation. RESULTS: Sustained increase in heart rate was associated with progressive bi-exponential shortening of the QT interval and APD. Flecainide prolonged...

Mode-field half-widths of Gaussian approximation for the fundamental mode of two kinds of optical waveguides

International Nuclear Information System (INIS)

Lian-Huang, Li; Fu-Yuan, Guo

2009-01-01

This paper analyzes the characteristic of matching efficiency between the fundamental mode of two kinds of optical waveguides and its Gaussian approximate field. Then, it presents a new method where the mode-field half-width of Gaussian approximation for the fundamental mode should be defined according to the maximal matching efficiency method. The relationship between the mode-field half-width of the Gaussian approximate field obtained from the maximal matching efficiency and normalized frequency is studied; furthermore, two formulas of mode-field half-widths as a function of normalized frequency are proposed

Limiter H-mode experiments on TFTR

Energy Technology Data Exchange (ETDEWEB)

Bush, C [Oak Ridge National Lab., TN (USA); Bretz, N L; Fredrickson, E D; McGuire, K M; Nazikian, R; Park, H K; Schivell, J; Taylor, G; Bitter, B; Budny, R; Cohen, S A; Kilpatrick, S J; LeBlanc, B; Manos, D M; Meade, D; Paul, S F; Scott, S D; Stratton, B C; Synakowski, E J; Towner, H H; Weiland, R M; Arunasalam, V; Bateman, G; Bell, M G; Bell, R; Boivin, R; Cavallo, A; Cheng, C Z; Chu, T K; Cowl,

1990-12-15

Limiter H-modes with centrally peaked density profiles have been obtained in TFTR using a highly conditioned graphite limiter. The transition to these centrally peaked H-modes takes place from the supershot to the H-mode rather than the usual L- to H-mode transition observed on other tokamaks. Bi-directional beam heating is required to induce the transition. Density peaking factors, n{sub e}(0)/{l angle}n{sub e}{r angle}, >2.3 are obtained and at the same time the H-mode characteristics are similar to those of limiter H-modes on other tokamaks and the global confinement, {tau}{sub E}, can be >2.5 times L-mode scaling. The TRANSP analysis shows that transport in these H-modes is similar to that of supershots within the inner 60 cm of the plasma, but the stored electron energy (calculated using measured values of T{sub e} and n{sub e}) is higher for the H-mode at the plasma edge. Microwave scattering near the edge shows broad spectra at k = 5.5 cm{sup {minus}1} which begin at the drop in D{sub {alpha}} radiation and are strongly shifted in the electron diamagnetic drift direction. At the same time beam emission spectroscopy shows a coherent mode near the boundary with m = 15--20 at 20--30 kHz which is propagating in the ion direction. During an ELM event these apparent rotations cease and Mirnov fluctuations in the 50--500 kHz increase in intensity.

Three mode Er3+ ring-doped fiber amplifier for mode-division multiplexed transmission

NARCIS (Netherlands)

Jung, Y.; Kang, Q.; Sleiffer, V.A.J.M.; Inan, B.; Kuschnerov, M.; Veljanovski, V.; Corbett, B.; Winfield, R.; Li, Z.; Teh, P.S.; Dhar, A.; Sahu, J.K.; Poletti, F.; Alam, S.U.; Richardson, D.J.

2013-01-01

We successfully fabricate three-mode erbium doped fiber with a confined Er3+ doped ring structure and experimentally characterize the amplifier performance with a view to mode-division multiplexed (MDM) transmission. The differential modal gain was effectively mitigated by controlling the relative

Electrophysiological effects of Chinese medicine Shen song Yang xin (SSYX) on Chinese miniature swine heart and isolated guinea pig ventricular myocytes.

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