Two-dimensional Photon Counting Research Articles

A Scintillating One-Dimensional Coordination Polymer Based on Cadmium(II), N,N′-(1,4-Phenylenedicarbonyl)diglycinate, and 2,2′-Bipyridine: Crystal Structure, Hirshfeld Surface Analysis, and Luminescence Lifetime Properties †

In recent years, several coordination polymers of different dimensions and metal–organic frameworks were tested and expected to be good candidates for closing the gap between organic and plastic scintillators on the one hand side and inorganic scintillators on the other hand side. In the present work, we report the synthesis and characterization of a novel one-dimensional scintillating coordination polymer based on cadmium(II), N,N′-(1,4-phenylenedicarbonyl)di-glycinate, and 2,2′-bipyridine. Crystals could be obtained from water–methanol solutions and the structure was determined by single-crystal diffraction. The coordination polymer exhibits scintillation under X-ray excitation and laser as well as UV-light induced photoluminescence with fast decay times. Photoluminescence and X-ray excited optical luminescence (XEOL) properties and decay times were performed using a two-dimensional photon counting streak camera system with a time resolution up to 20 ps. The non-covalent interactions and supramolecular assemblies as a potential multiplier of the scintillating effect were investigated with the aid of a Hirshfeld surface analysis. The quality and phase purity of the used crystals and pellets was clarified by powder diffraction and Rietveld refinement.

Advanced Non-Destructive in Situ Characterization of Metals with the French Collaborating Research Group D2AM/BM02 Beamline at the European Synchrotron Radiation Facility

The ability to non-destructively measure the structural properties of devices, either in situ or operando, are now possible using an intense X-ray synchrotron source combined with specialized equipment. This tool attracted researchers, in particular metallurgists, to attempt more complex and ambitious experiments aimed at answering unresolved questions in formation mechanisms, phase transitions, and magnetism complex alloys for industrial applications. In this paper, we introduce the diffraction diffusion anomale multi-longueur d’onde (D2AM) beamline, a French collaborating research group (CRG) beamline at the European Synchrotron Radiation Facility (ESRF), partially dedicated to in situ X-ray scattering experiments. The design of the beamline combined with the available equipment (two-dimensional fast photon counting detectors, sophisticated high precision kappa diffractometer, a variety of sample environments, continuous scanning for X-ray imaging, and specific software for data analysis) has made the D2AM beamline a highly efficient tool for advanced, in situ synchrotron characterization in materials science, e.g., single crystal or polycrystalline materials, powders, liquids, thin films, or epitaxial nanostructures. This paper gathers the main elements and equipment available at the beamline and shows its potential and flexibility in performing a wide variety of temporally, spatially, and energetically resolved X-ray synchrotron scattering measurements in situ.

Multi-speckle X-ray photon correlation spectroscopyin the ultra-small-angle X-ray scatteringrange.

Multi-speckle X-ray photon correlation spectroscopy (XPCS) measurements in the ultra-small-angle range are performed using a long pinhole collimation instrument in combination with two-dimensional photon-counting and high-sensitivity imaging detectors. The feasibility of the presented setup to measure dynamics on different time and length scales pertinent to colloidal systems is shown. This setup offers new research opportunities, such as for example in the investigation of non-equilibrium dynamics in optically opaque, complex systems over length scales from tens of nanometres to several micrometres. In addition, due to the short duration of the X-ray exposure involved in the ultra-small-angle range, possible radiation-induced effects are alleviated. Furthermore, the performance of two different detectors, a photon-counting Pilatus 300K and an integrating FReLoN CCD, are compared, and their applicability for accurate XPCS measurements is demonstrated.

Photon counting imaging with an electron-bombarded CCD: towards a parallel-processing photoelectronic time-to-amplitude converter.

We have used an electron-bombarded CCD for optical photon counting imaging. The photon event pulse height distribution was found to be linearly dependent on the gain voltage. We propose on this basis that a gain voltage sweep during exposure in an electron-bombarded sensor would allow photon arrival time determination with sub-frame exposure time resolution. This effectively uses an electron-bombarded sensor as a parallel-processing photoelectronic time-to-amplitude converter, or a two-dimensional photon counting streak camera. Several applications that require timing of photon arrival, including Fluorescence Lifetime Imaging Microscopy, may benefit from such an approach. A simulation of a voltage sweep performed with experimental data collected with different acceleration voltages validates the principle of this approach. Moreover, photon event centroiding was performed and a hybrid 50% Gaussian/Centre of Gravity + 50% Hyperbolic cosine centroiding algorithm was found to yield the lowest fixed pattern noise. Finally, the camera was mounted on a fluorescence microscope to image F-actin filaments stained with the fluorescent dye Alexa 488 in fixed cells.

Instrumentation for X-ray Excited and Laser Induced Fluorescence Lifetime Spectroscopy Using Two-Dimensional Photon Counting

A table top picosecond pulsed X-ray and laser induced fluorescence spectrometer using two-dimensional photon counting is presented. With this streak camera system it is possible to measure fluorescence events in a wavelength range from 200-850 nm. Measuring results are full time resolved fluorescence spectra with a temporal resolution up to 20 ps after deconvolution. The instrumental response function (IRF) of the system is around 60 ps for laser excitation and 80 ps for X-ray excitation. For a performance test well known inorganic (CsI, CsI:Tl) and organic scintillators (anthracene) as well as rhodamine 6G for laser induced fluorescence are measured and evaluated. The easily manageable system shows satisfying results in agreement with literature values.

High sensitivity microchannel plate detectors for space extreme ultraviolet missions

Microchannel plate (MCP) detectors have been widely used as two-dimensional photon counting devices on numerous space EUV (extreme ultraviolet) missions. Although there are other choices for EUV photon detectors, the characteristic features of MCP detectors such as their light weight, low dark current, and high spatial resolution make them more desirable for space applications than any other detector. In addition, it is known that the photocathode can be tailored to increase the quantum detection efficiency (QDE) especially for longer UV wavelengths (100-150 nm). There are many types of photocathode materials available, typically alkali halides. In this study, we report on the EUV (50-150 nm) QDE evaluations for MCPs that were coated with Au, MgF(2), CsI, and KBr. We confirmed that CsI and KBr show 2-100 times higher QDEs than the bare photocathode MCPs, while Au and MgF(2) show reduced QDEs. In addition, the optimal geometrical parameters for the CsI deposition were also studied experimentally. The best CsI thickness was found to be 150 nm, and it should be deposited on the inner wall of the channels only where the EUV photons initially impinge. We will also discuss the techniques and procedures for reducing the degradation of the photocathode while it is being prepared on the ground before being deployed in space, as adopted by JAXA's EXCEED mission which will be launched in 2013.

Photon Counting Histogram Analysis for Two-Dimensional Systems

Photon counting statistics in 3D photon counting histogram analysis for one-photon excitation is a function of the number of molecules of particular brightness in the excitation-detection volume of a confocal microscope. In mathematical form that volume is approximated by a three-dimensional Gaussian function which is embedded in the PCH theoretical equations. PCH theory assumes that a molecule can be found anywhere inside the excitation-detection volume with equal probability. However, one can easily imagine systems in which this assumption is violated because molecules are constrained by the geometry of the sample. For example, molecules on a surface or in a membrane would be constrained to two dimensions. To enable the analysis of such systems by PCH, the theoretical framework requires modification. Herein, we present an extension of the PCH analysis to systems where molecules exist in thin structures that are effectively two-dimensional. The method, aptly called two-dimensional photon counting histogram (2D PCH), recovers the number of fluorescent particles per unit area and their molecular brightness. Both theoretical background and experimental results are presented. The theory was tested using computer-simulated and experimental 2D PCHs obtained from confocal experiments. We demonstrate that this modification of the theoretical framework provides a tool to extract data that reveal states of aggregation, surface photophysics, and reactivity.

Two-dimensional photon counting imaging detector based on a Vernier position sensitive anode readout

A two-dimensional photon counting imaging detector based on a Vernier position sensitive anode is reported. The decode principle and design of a two-dimensional Vernier anode are introduced in detail. A photon counting imaging system was built based on a Vernier anode. The image of very weak optical radiation can be reconstructed by image processing in a period of integration time. The resolution is superior to 100 μm according to the resolution test. The detector may realize the imaging of very weak particle flow of high-energy photons, electrons and ions, so it can be used for high-energy physics, deep space exploration, spectral measurement and bio-luminescence detection.

Thermoluminescence from a dosimeter sheet irradiated with accelerated electron beams

Ultra-low intensity electron beams generated from an electron linear accelerator have been applied to the investigation of the response of the thermoluminescence (TL) sheet for irradiation. The TL image has been measured with a high-sensitivity TL imaging system developed by using a two-dimensional photon counter. The imaging system was expected to be a profile monitor for ultra-low intensity electron beams and to be a high-sensitivity electron beam monitor having a wide dynamic range. In the present work the TL images of the electron beam profile has been observed on the TL sheet irradiated with the beam. There has been the linear relation between the number of TL photons emitted from the sheet and the electron beam fluence in the fluence range over five orders of magnitude. From the results for irradiation at energies of 6 and 10 MeV the cause of the TL due to the irradiation is discussed.

TL imaging system by using a two-dimensional photon counter

The characteristics of the new thermoluminescence (TL) imaging system have been investigated. The system consists of a TL sheet, its holder with a temperature controller and a two-dimensional photon counter. The photon counter has the highest sensitivity in imaging devices and the wide dynamic range has been expected for the imaging system. The TL images of the 226Ra gamma-ray irradiation-dose distribution and the glow histograms have been obtained in the experiments. The new high-sensitivity TL imaging system has been developed in the present work. From the experimental results for the response of the TL sheet to gamma rays the fading effect has been discussed.

A counting CdTe pixel detector for hard X-ray and /spl gamma/-ray imaging

A 0.5-mm-thick cadmium telluride (CdTe) semiconductor pixel sensor with 1024 pixels has been bump-bonded onto a two-dimensional (2-D) single photon counting pixel read out chip (MPEC 2.1) using a special gold-stud technique. The pixel size is 200 /spl times/ 200 /spl mu/m/sup 2/, the active area is 6.4 /spl times/ 6.4 mm/sup 2/. The successful operation of this high-Z imaging pixel device is demonstrated. Noise and threshold dispersion as well as the imaging performance are reported.

The analysis of site-directed mutants in the glutamate 189 and histidine 190 in the D1 protein of photosystem II

The primary charge separation in photosystem (PS) II takes place within 3 ps, generating highly oxidative P680+. Site-directed mutagenesis has been proven to be a valuable tool for elucidating the function of each amino acid residue in PSII. Several mutants at glutamate-189 and histidine-190 in the putative cd-helix of the D1 protein were constructed in Chlamydomonas reinhardtii, and the effects of mutation on PS II functions were studied. In E189Q and E189L mutants, they were able to grow photoautotrophycally, but the oxygen evolution activity decreased to a half of the wild type. On the other hand, E189D and H190R mutants lost the oxygen evolution activity, which led to the non-photoautotrophical phenotype. In order to obtain further insights on the effects of the mutations, two-dimensional fluorescence photon counting experiments were carried out. The results showed that the fluorescence lifetime at 77K was markedly prolonged in all mutants, suggesting that the yield of the charge separation becomes to be lower due to the decrease in redox potential of P680 and/or Yz. In PS II reaction center, isolated from His-tagged versions of these mutants, the activity of pheophytin photoacummulation was reduced to 60-70 % of the control. Therefore, it is indicated that these two amino acids exist in the close vicinity of P680 and play important role(s) in the charge separation, in addition to their involvement to the donor side function as revealed E189D and H190R mutants.

微弱スペクトルの高S/N比計測のための高効率2次元光子計数処理

An efficient two-dimensional photon counting procedure is described for high-S/N measurements of weak spectra using an image-intensified CCD camera. By using a procedure which utilizes the signal intensities of more than one pixel in judging a single photon detection, the photon detection efficeincy was increased by _??_40% in comparison with the method where a photon detection is based on the indensity of one pixel.

Two-dimensional photon counting imaging and spatiotemporal characterization of ultraweak photon emission from a rat’s brain in vivo

The process of metabolic reactions within living cells leads to spontaneous ultraweak light emission. The development of a system for highly sensitive imaging and spatiotemporal analysis of ultraweak photon emission from a rat’s brain is reported in this paper. The equipment used in this experiment consists of a two-dimensional photon-counting tube with a photocathode measuring 40 mm in diameter, a highly efficient lens system, and an electronic device to record time series of a photoelectron train with spatial information. The sensitivity and ability to extract spatiotemporal information from sequential data of a single photoelectron train were examined. The minimum detectable radiant flux density of the system was experimentally estimated to be 9.9×10 −17 W/cm 2 with a 1-s observation time. Spontaneous photon emission was demonstrated from an exposed rat’s cortex in vivo without adding any chemical agent or employing external excitation. An image of ultraweak photon emission was compared with one obtained after cardiac arrest. The intensity after cardiac arrest was depressed to approximately 60% of before that. The regional properties of time courses of emission intensity were also demonstrated, indicating the potential usefulness for spatiotemporal characterization of photon emission with mapping of physiological information such as oxidative stress. This technology constitutes a novel method, with the potential to extract pathophysiological information from the central nervous system.

Status of the digital pixel array detector for protein crystallography

A two-dimensional photon counting digital pixel array detector is being designed for static and time resolved protein crystallography. The room temperature detector will significantly enhance monochromatic and polychromatic protein crystallographic through-put data rates by more than three orders of magnitude. The detector has an almost infinite photon counting dynamic range and exhibits superior spatial resolution when compared to present crystallographic phosphor imaging plates or phosphor coupled CCD detectors. The detector is a high resistivity N-type Si with a pixel pitch of 150×150 μm, and a thickness of 300 μm, and is bump bonded to an application specific integrated circuit. The event driven readout of the detector is based on the column architecture and allows an independent pixel hit rate above 1 million photons/s/pixel. The device provides energy discrimination and sparse data readout which yields minimal dead-time. This type of architecture allows a continuous (frameless) data acquisition, a feature not found in any current detector being used for protein crystallographic applications. For the targeted detector size of 1000×1000 pixels, average hit rates greater than 8 billion photons/s for the complete detector appears achievable. This paper will present a review of the 8×8 detector array pixel performance which includes the analog amplifier response and the photon counting capabilities. In addition, operational results of a 16×16 detector array prototype, that includes both the analog amplifier and digital readout circuitry functioning together on one integrated circuit.

Observation of photon emissions from hot electrons and latch-up at the cleaved surface of CMOS structures

Hot-electron-induced and latchup-induced photon emissions can be directly observed from the cleaved surface of CMOS test structures using a two-dimensional photon counting system. Observations of an NMOSFET under near-drain-breakdown conditions revealed the location and intensity profile of both hot-electron-induced photon emissions and also carrier recombination radiation arising from bipolar action caused by impact ionization. In addition, the photon intensity profile of latch-up-induced emissions clearly showed two peaks. The observation of a cleaved surface makes it possible to determine the exact location of photon emissions because the aluminum electrode does not mask them.

Growth Control and Biophoton Radiation by Plant Hormones in Red Bean

The growth kinetics of seeds of red beans ( Phaseolus angularis ) was investigated by externally adding various hormones (gibberellin (GA3)), abscisic acid (ABA) and indole acetic acid (IAA)) during germination. For root growth of red beans, GA3 always acted as an activator while ABA as an inhibitor. IAA was both an activator and an inhibitor depending on its concentration. Root growth could be described by a stochastic logistic equation. The hormone concentration dependences of coefficients of the equation were determined. The hormone influences on biophoton radiation were also investgated. With GA3, the intensity of spontaneous bioluminescence increased with time and showed two strong radiation periods, in which strong localization of bioluminescence was induced. However with ABA and IAA, weaker bioluminescences were observed. The location of the strong radiation induced by GA3 was determined as the growing point near a root cap, by use of a two-dimensional photon counting system.

極微弱生物フォトン発光の2次元時・空間特性分析による生体情報抽出法の検討

Ultraweak photon emission from biological organisms, commonly referred as biophoton emission, is known to be closely related to vital processes and biological activities, observable quite generally in nature in the absence of any external excitation. The intensity of the photon emission is estimated to be in the order of less than 10-16 W/cm2 on the living surface. The excitation mechanisms of this phenomenon are based on chemical excitation in the living system and considered to originate from internal biochemical reactions associated with metabolic processes. A number of phenomena is indicative the relationship between biophoton emission and physiological and/or pathological conditions. The purpose of our study is to explore the relationship/correlation between physiological state and biophoton emission phenomena so as to extract possible information on the state of biological order and space-time organization of metabolic processes. This paper reports a newly developed technology to measure space-time properties and characterize the dynamics of ultraweak biophoton emission in the single photoelectron counting region. We also describe the spatio-temporal distribution and correlation analysis of ultraweak biophoton emission from soybean seedlings, based on photoelectron pulse time series and position measurement techniques, as a first example. We performed experiments using etiolated soybean seedlings with or without physical (heat, mechanical injury) or chemical (hydrogen peroxide) stimulation. Spatio-temporal response of biophoton emission, indicative of the transmission of some stimulus was observed. In order to clarify the propagation of the response quantitatively, cross-correlation analysis was also carried out. We demonstrate the potential usefulness of a novel two-dimensional photon counting technique to characterize spatio-temporal dynamics of the biophoton emission. From these results, it is our belief that by analyzing the spatio-temporal distribution, spatial and temporal correlation of the biophoton emission, mechanisms of signal transmission within a living system could be explored.

Development of a new fluorescence decay measurement system using two-dimensional single-photon counting

Abstract A new fluorescence decay measurement system has been developed. The system consists of a spectrograph and a new two-dimensional photon counter. The combination enables measurements to be made of the fluorescence decay as a function of time and wavelength simultaneously. The time resolution is better than 5 ps with deconvolution processing, and the wavelength resolution is approximately 0.15 nm with 1200 grooves mm−1 gratings. The dynamic range is 105. The instrument response function (IRF) of the system is nearly gaussian, and has no tail or “after pulses” which are commonly observed using a photomultiplier in a time-correlated photon counting (TCPC) system. Therefore fast fluorescence decay of several tens of picoseconds can be measured accurately. In addition, the two-dimensional single-photon counting can be performed without wavelength scanning, so that the wavelength-dependent fluorescence decay can be easily and direcly observed with a fast throughput and a high signal-to-noise ratio. The principle of two-dimensional photon counting is discussed together with characteristics including linearity and statistical behavior.

The position of PSR 0540-69

view Abstract Citations (17) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Position of PSR 0540-69 Shearer, A. ; Redfern, M. ; Pedersen, H. ; Rowold, T. ; O'Kane, P. ; Butler, R. ; O'Byrne, C. ; Cullum, M. Abstract Using time-resolved two-dimensional photon counting techniques we have found an accurate position for the X-ray and optical pulsar PSR 0540-69. Our position using postexposure variable aperture photometry confirms the position suggested by Caraveo et al. Publication: The Astrophysical Journal Pub Date: March 1994 DOI: 10.1086/187233 Bibcode: 1994ApJ...423L..51S Keywords: Nebulae; Optical Measurement; Pulsars; Radiation Detectors; Two Dimensional Models; X Ray Astronomy; Apertures; Cameras; Counting; Photons; Telephotometry; Telescopes; Time Dependence; Astrophysics full text sources ADS | data products SIMBAD (1)