CCD Detector Research Articles

(Invited) Novel Synthesis Procedure for Endohedral-Fullerenes Using Laser Ablation Plasma from Solid Material and Vaporized Fullerenes

Since a fullerene was discovered in 1985, fullerene has attracted much attentions [1]. A unique feature of the fullerene that has the spherical structure with hollow interior allows a fullerene to accommodate any other atoms and molecules. Especially, the fullerenes containing other atoms which is called as endohedral fullerene have been expected to be applied in medical uses, electronics systems and so on [2]. In many cases, endohedral fullerenes have been synthesized by ion implantation, co-vaporization of carbon and metal atoms [3], or ion plasma irradiation technique for non-metal material [4]. However, these procedures have remained several issues. One of the critical issues is low production rate for endohedral fullerene synthesize due to difficulties in controlling a physical and a chemical property during synthesizing process. To increase the production efficiency of endohedral fullerene, it is required to optimize elementary process between fullerenes and injected atoms.Under these situations, we recently developed a novel procedure to synthesize endohedral fullerenes that induce the collision of vaporized fullerenes and ablated particles produced by the laser ablation of a solid material. Here, a Q-switched Nd:YAG Laser (Continuum, Powerlite DLS8000) with a wavelength of 1064 nm, a pulse-width of 9 ns, a laser energy of up to 1 J, and a pulse-frequency of up to 10Hz was used. Laser light was focused to be 50 m in diameter on the target surface. In this procedure, N@C60 was synthesized using the ablation of boron nitride material. From the previous studies [4], it is quite important for encapsulated particles to have about 100 eV. Optical emission spectrum of ablated particles by a polychromator (Bunkokeiki, CT-1000) with an intensified CCD detector (Princeton Instruments, PI-Max) was measured, and Doppler shift of the spectrum was estimated. The result showed that the kinetic energy of nitrogen ions was in the range of 20 to 65 eV by controlling the energy of the incident laser beam. The synthesis of N@C60 was conducted with a nitrogen kinetic energy of 65 eV, fullerenes vaporizing temperature of 800 degree Celsius, and a total reaction time of one hour. By optimizing the kinetic energy of ablated particles, synthesis of N@C60 was succeeded [5]. Existence of N@C60 in the toluene solution was confirmed by an electron spin resonance measurement (Elexsys E500, Bruker) without purification by high performance liquid chromatography [6]. The purity of produced N@C60 was two orders of magnitude higher than that achieved using alternative physical synthetic methods that use solid materials, such as arc discharge and co-evaporation methods. However, the purity must be increased by at least two orders of magnitude for the commercial use. Therefore, it is necessary to enhance the purity by optimizing experimental conditions such as laser energy, laser wavelength, amount of ion flux with appropriate energy, repetition rate of laser pulses, laser duration time, area of the laser ablation, and so on. In the meeting, novel synthesis procedure for endohedral-fullerenes using laser ablation plasma from solid material and vaporized fullerenes will be presented.AcknowledgmentsThis study was financially supported by JSPS KAKENHI Grant No. 25287157 from the Ministry of Education, Culture, Sports, Science and Technology of Japan.[1] H. W. Kroto, et.al., Nature 318, 162-163 (1985).[2] H. Shinohara, Rep. Prog. Phys. 63, 843-892 (2000).[3] Alexey A. Popov, et.al., Chem. Rev. 113, 5989-6113 (2013).[4] S.C. Cho, et.al., J. Appl. Phys. 117, 123301 (2015).[5] H. Itagaki, et al., AIP Advances 9-7 (075324), 1-7 (2019).[6] T.A. Murphy, et al., Phys. Rev. Lett. 77-6, 1075 (1996).

Gated detection of supercontinuum pulses enables optical probing of solid and molten silicates at extreme pressure-temperature conditions.

Optical studies of materials at high pressure-temperature (P-T) conditions provide insights into their physical properties that may be inaccessible to direct determination at extreme conditions. Incandescent light sources, however, are insufficiently bright to optically probe samples with radiative temperatures above ∼1000 K. Here we report on a system to perform optical absorption experiments in a laser-heated diamond anvil cell at T up to at least 4000 K. This setup is based on a pulsed supercontinuum (broadband) light probe and a gated CCD detector. Precise and tight synchronization of the detector gates (3 ns) to the bright probe pulses (1 ns) diminishes the recorded thermal background and preserves an excellent probe signal at high temperature. We demonstrate the efficiency of this spectroscopic setup by measuring the optical absorbance of solid and molten (Mg,Fe)SiO3, an important constituent of planetary mantles, at P ∼30 GPa and T ∼1200 K to 4150 K. Optical absorbance of the hot solid (Mg,Fe)SiO3 is moderately sensitive to temperature but increases abruptly upon melting and acquires a strong temperature dependence. Our results enable quantitative estimates of the opacity of planetary mantles with implications to their thermal and electrical conductivities, all of which have never been constrained at representative P-T conditions, and call for an optical detection of melting in silicate-bearing systems to resolve the extant ambiguity in their high-pressure melting curves.

A novel approach to separate absorption, refraction and scattering in analyzer based lung imaging

In analyzer based imaging (ABI) scattering can be efficiently separated from refraction and absorption effects by acquiring three images of the sample. In the scattering image the lungs appear as areas of high intensity signal (area contrast), which is modulated by the local thickness of the scattering tissue intersecting the X-ray path. The scattering signal is also included in the so-called apparent absorption image, where it adds to the absorption contrast thanks to the extinction of rays which are deviated outside the analyzer crystal's acceptance window. The presence of scattering can be emphasized in the ratio between two images acquired with a strongly detuned and a perfectly tuned analyzer crystal, respectively: we name this ratio as the amplified scatter image. In this paper we present ABI scattering methods applied to postmortem mouse lung imaging to assess their diagnostic value. For this purpose images have been acquired at the SYRMEP beamline of the ELETTRA synchrotron in Trieste (Italy) with the Argus time delay integration CCD detector at a photon energy of 25 keV . Subsequently the parametric images, including the amplified scatter image have been obtained, and contrast and signal-to-noise ratio have been evaluated. It is noteworthy that images have been acquired with a radiation dose of some mGy, thus are compatible with dose restricted medical imaging settings such as mammography.

Performance Verification of the EXtreme PREcision Spectrograph

Abstract The EXtreme PREcision Spectrograph (EXPRES) is a new Doppler spectrograph designed to reach a radial-velocity measurement precision sufficient to detect Earth-like exoplanets orbiting nearby, bright stars. We report on extensive laboratory testing and on-sky observations to quantitatively assess the instrumental radial-velocity measurement precision of EXPRES, with a focused discussion of individual terms in the instrument error budget. We find that EXPRES can reach a single-measurement instrument calibration precision better than 10 cm s−1, not including photon noise from stellar observations. We also report on the performance of the various environmental, mechanical, and optical subsystems of EXPRES, assessing any contributions to radial-velocity error. For atmospheric and telescope related effects, this includes the fast tip-tilt guiding system, atmospheric dispersion compensation, and the chromatic exposure meter. For instrument calibration, this includes the laser fRequency comb (LFC), flat-field light source, CCD detector, and effects in the optical fibers. Modal noise is mitigated to a negligible level via a chaotic fiber agitator, which is especially important for wavelength calibration with the LFC. Regarding detector effects, we empirically assess the impact on the radial-velocity precision due to pixel-position nonuniformities and charge transfer inefficiency (CTI). EXPRES has begun its science survey to discover exoplanets orbiting G-dwarf and K-dwarf stars, in addition to transit spectroscopy and measurements of the Rossiter–McLaughlin effect.

Search for light mediators in the low-energy data of the CONNIE reactor neutrino experiment

The CONNIE experiment is located at a distance of 30 m from the core of a commercial nuclear reactor, and has collected a 3.7 kg-day exposure using a CCD detector array sensitive to an ∼1 keV threshold for the study of coherent neutrino-nucleus elastic scattering. Here we demonstrate the potential of this low-energy neutrino experiment as a probe for physics Beyond the Standard Model, by using the recently published results to constrain two simplified extensions of the Standard Model with light mediators. We compare the new limits with those obtained for the same models using neutrinos from the Spallation Neutron Source. Our new constraints represent the best limits for these simplified models among the experiments searching for CEνNS for a light vector mediator with mass {M}_{Z^{prime }} < 10 MeV, and for a light scalar mediator with mass Mϕ< 30 MeV. These results constitute the first use of the CONNIE data as a probe for physics Beyond the Standard Model.

Measurement of molybdenum ion density for L-mode and H-mode plasma discharges in the EAST tokamak**Project supported by the National Key Research and Development Program of China (Grant No. 2017YFE031300), the Key Program of Research and Development of Hefei Science Center of China (Grant No. 2017HSC-KPRD002), the National Natural Science Foundation of China (Grant No. 11805231), the Natural Science Foundation of

We report the measurement of total molybdenum ion density for L-mode and H-mode plasmas on EAST using spectral lines observation and calculation based on an impurity transport code. A flat-filed extreme ultraviolet spectrometer with some spatial resolution is used to obtain the radial profiles of molybdenum spectral line emissions. The absolute calibration for the extreme ultraviolet spectrometer is finished by comparing the calculated bremsstrahlung intensity with the readings of CCD detector. Molybdenum ion transport study is performed using the radial ion density profiles and one-dimensional impurity transport code STRAHL. The total molybdenum density profiles are determined from the transport analysis. The molybdenum density during L-mode and H-mode phases are obtained, which are about 3 and 4 orders of magnitude smaller than the electron density, respectively. An inward pinch is found during the H-mode phase that leads to the peaked profile of molybdenum density.

CCD Based Detector for Detection of Abrin Toxin Activity.

Abrin is a highly potent and naturally occurring toxin produced in the seeds of Abrus precatorius (Rosary Pea) and is of concern as a potential bioterrorism weapon. There are many rapid and specific assay methods to detect this toxic plant protein, but few are based on detection of toxin activity, critical to discern biologically active toxin that disables ribosomes and thereby inhibits protein synthesis, producing cytotoxic effects in multiple organ systems, from degraded or inactivated toxin which is not a threat. A simple and low-cost CCD detector system was evaluated with colorimetric and fluorometric cell-based assays for abrin activity; in the first instance measuring the abrin suppression of mitochondrial dehydrogenase in Vero cells by the MTT-formazan method and in the second instance measuring the abrin suppression of green fluorescent protein (GFP) expression in transduced Vero and HeLa cells. The limit of detection using the colorimetric assay was 10 pg/mL which was comparable to the fluorometric assay using HeLa cells. However, with GFP transduced Vero cells a hundred-fold improvement in sensitivity was achieved. Results were comparable to those using a more expensive commercial plate reader. Thermal inactivation of abrin was studied in PBS and in milk using the GFP-Vero cell assay. Inactivation at 100 °C for 5 min in both media was complete only at the lowest concentration studied (0.1 ng/mL) while treatment at 63 °C for 30 min was effective in PBS but not milk.

Transversal dose profile reconstruction for clinical proton beams: A detectors inter-comparison

PurposeThe main purpose of this work is the inter-comparison between different devices devoted to the transversal dose profile recostruction for daily QA tests in proton therapy. MethodsThe results obtained with the EBT3 radiochromic films, used as a reference, and other common quality control devices, have been compared with those obtained with a beam profiling system developed at the “Laboratori Nazionali del Sud” of Italian Institute for Nuclear Physics (INFN-LNS, Catania, Italy). It consists of a plastic scintillator screen (thickness 1 mm), mounted perpendicularly to the beam axis and coupled with a highly sensitive CCD detector in a light-tight box. Results and conclusionThe tests, carried out both at the INFN-LNS and Trento Proton Therapy Center facilities, show, in general, a good agreement between the different detectors. The beam profiling system, in particular, appears to be a promising quality control device for 2-D relative dosimetry, because of its linear response in a dose rate range useful for proton therapy treatments, its high spatial resolution and its short acquisition and processing time.

Innovative design of a methodology for the simultaneous determination of compounds by kinetic-spectroscopy three-dimensional chemiluminescence.

This report presents a novel methodology based in the quickly acquisition of full UV-vis range spectra combined with the joint determination of kinetic parameters and chemiluminescence signals. Then this technique allows obtaining three-dimensional chemiluminescence spectra profiles containing kinetic and spectroscopic information. That is especially useful for resolving mixtures of luminophors because of more analytical information for each analyte is available increasing the selectivity relative to conventional chemiluminescence methods. To accomplish this, a conventional Back-Thinned CCD detector is used and the three-dimensional chemiluminescence spectra is subsequently processed so that two-dimensional spectra with different trajectories can be obtained by dedicated software CLTotal. The potential of the proposed analytical methodology was assessed for the simultaneous determination of two polycyclic aromatic hydrocarbons. The chemiluminescent reaction between DNPO and hydrogen peroxide induced by their presence was used to record 3D spectra and the software CLTotal to subsequently construct linear variable-angle trajectories in the spectra, in order to obtain more selective 2D spectra facilitating the simultaneous determination of the analytes. The results of the statistical analysis testify to the usefulness of the proposed method for the intended purpose.

Focus on photonics, spectrometry, and spectroscopy

Focus on photonics, spectrometry, and spectroscopy

Krystalová struktura phurcalitu, Ca2[(UO2)3O2(PO4)2]·7H2O, z Jáchymova

A rare supergene uranyl phosphate mineral, phurcalite, was found on a few specimens originating from the dump material of the Eduard shaft, the Jáchymov ore district, Czech Republic. Phurcalite forms yellow to yellowish-orange perfect prismatic crystals, reaching up to 3 - 4 mm in cavities of vuggy quartz-dominated gangue. Phurcalite was found in the association with walpurgite, uranophane-α, and members of the metatorbernite-metazeunerite series. According to single-crystal X-ray data phurcalite is orthorhombic, space group Pbca, with a 17.3785(8), b 15.9864(6), c 13.5477(6) Å, and V 3763.8(3) Å3. Its crystal structure has been refined to R = 3.56 % for 3488 unique observed reflections [Iobs&gt;3σ(I)] collected on a Rigaku SuperNova X-ray diffractometer with an Atlas S2 CCD detector and focused MoKα radiation. The results of the structure refinement are in line with the recently published structure refinement of phurcalite from Shinkolobwe (Africa). Nevertheless, in phurcalite from Jáchymov, the substitution of As for P takes place at greater extent. The structural formula obtained for the crystal from Jáchymov is Ca2[(UO2)3O2(PO4)1.753(AsO4)0.247]·7H2O, Z = 8, Dcalc. = 4.409 g/cm3.

Narrow-Band Survey of Star Forming Regions

We present the results of a narrow-band H and [S II] imaging survey of the star-forming regions in Galaxy. Main tasks of this survey are the search and the studies of the new Herbig-Haro objects and collimated outflows, which are the main indicators of active processes of star formation. Besides, the eruptive stars of very rare types: FUors, EXors, UXors will be searched as well. As the main targets of this survey the R associations, young stellar objects associated with compact reflection nebulae as well as the deeply embedded infrared sources in molecular clouds are selected. Observations are performed with 1-m Schmidt telescope at Byurakan Observatory, which is equipped with modern CCD detector. We plan to significantly expand the list of HH objects by using the high quantum efficiency of this system as well as the telescope's high focal ratio (F/2), which allows detecting low surface brightness objects, and its large field of view.

A Pilot Study on High Wavenumber Raman Analysis of Human Dental Tissues.

Water plays a critical role in dental tissues including enamel and dentin. The characterization of water structure analysis was primarily conducted by nuclear magnetic resonance. Raman spectroscopy is a powerful analytic technology with capability for structure analysis in materials. However, acquiring high wavenumber Raman signals from dental tissues was challenging due to either the fluorescence interference under laser illumination or reduced sensitivity of CCD detectors. In this study, we demonstrate a pilot research on high wavenumber Raman analysis in dental tissues using a customized Raman spectrometer based on an InGaAs detector. A signal located at 3570 cm-1 is found dominating the O-H region Raman spectra of enamel but is barely detectable from dentin. The profiles of the high wavenumber region Raman spectra changes with the locations in enamel, as well as the polarization of the excitation laser beam. The results suggest that the size or crystallinity differences of hydroxyapatite crystals are the main cause of the spectral variation from dentin to enamel, and could be partially responsible for the variation among different locations in enamel.

Influence of distance between target surface and focal point on CN emission of nanosecond laser-induced PMMA plasma in air

Laser-induced breakdown spectroscopy (LIBS) is a technique for spectral composition analysis of materials containing atomic and ionic emission lines, as well as a few molecular emission bands. Here we focused our study on molecular emission from CN (B2∑+→X2∑+) based on LIBS method. Polymethyl methacrylate (PMMA) was ablated by employing a Nd:YAG laser system in air under atmospheric pressure. In the ultraviolet range, the molecular emission intensities of CN violet bands were observed with a spectrometer equipped with an intensified CCD detector. The effect of distance between sample surface and focal point (DTSFP) on the intensities of molecular emission was studied in detail. The results showed that the molecular emission intensities of CN violet bands exhibited a strong dependence on the DTSFP. As the surface of the PMMA sample approached the focal point gradually, the emission intensity of CN increased at first and then dropped down. In addition, vibrational temperature of CN molecule was also calculated. The vibrational temperature showed the similar change in the emission intensity, while the position at the maximum vibrational temperature was inconsistent with the position at the CN intensity.

Laser-induced breakdown spectroscopy assisted by machine learning for olive oils classification: The effect of the experimental parameters

Laser Induced Breakdown Spectroscopy (LIBS) was combined with some machine learning techniques, such as Principal Components Analysis (PCA) and Linear Discriminant Analysis (LDA) in order to obtain useful information concerning the classification of olive oil samples (authentication of their geographic origin) and the detection of adulteration. Since the plasma characteristics can depend substantially on the state of a sample (solid, gas or liquid) three different configurations of handling the sample were examined, spray of olive oil, a thin laminar flow and the free surface of few gr of olive oil sample. Then, the effects of experimental parameters, such as the laser energy, the temporal gating conditions (i.e., delay time and integration time) of the CCD detector of the spectrometer, on the plasma characteristics and subsequently on the classification results, were thoroughly investigated and analyzed. The combination of LIBS with the machine learning techniques used, resulted in excellent classification results of the olive oils studied, achieving classification accuracies of 100%.

THREE SPECTROSCOPIC BINARIES IN THE BRIGHT STAR CATALOG SUPPLEMENT

This paper presents spectroscopic orbits of three binaries, HD 121212, HD 148434 and HD 148912, with evolved primaries and periods of order a year, found in a survey of late-type stars listed in the Supplement to the Yale Bright Star Catalog. All the orbits were determined from observations made with the DAO 1.2-m telescope and coudé spectrograph. Observations were obtained using the radial velocity spectrometer until it was decommissioned in 2004, and since then using a CCD detector and cross-correlating the spectra with those of standard stars.

Preliminary geometric parameters optimization of lobster-eye-type wide field of view soft x-ray imager

The lobster-eye optical system is widely used in the wide field of view (FOV) soft x-ray imaging device. The payload soft x-ray imager (SXI) onboard the solar wind magnetosphere ionosphere link explorer satellite will apply this technology to achieve panoramic imaging of the dayside magnetosphere. In order to optimize the imaging performance of SXI, we focus on geometric parameters optimization of a lobster-eye lens. The results show an appropriate microchannel ratio of length to width of lobster-eye optics with radius of curvature of 600 mm could be 30:1 (microchannel width of 40 μm and length of 1.2 mm). For a monochromatic parallel light source with energy of 1 keV, this combination of parameters can theoretically provide relatively large total effective area of about 15.52 cm2 and focusing efficiency of about 0.2887 along with spatial angular resolution of about 6 arc min at the center of FOV. Combined with the actual lobster-eye optics, the aberrations from deformation of the microchannel, the deviation of radius of curvature and planar detector are analyzed. For SXI with planar CCD detector, an optimum focal length could be 304.2 mm to ensure better resolution in full FOV.

Quasi single-shot two-pulse tilted pulse front autocorrelator coupled with spatial chirp and spectral divergence monitor for ultrashort pulsed laser beams

Simultaneous single-shot unambiguous detection and measurement of pulse front tilt, spatial chirp, spectral divergence and pulse width has been carried out using two-pulse tilted pulse-front autocorrelator (TP-TPFAC) coupled with spectral interferometry using small part of laser beam intercepted from Mach Zehnder delay unit of TP-TPFAC generating two delayed and spatially inverted pulses. Error in estimation of rotation angle of autocorrelation (AC) trace due to accidental improper positioning of CCD detector is avoided by measuring angle between AC traces corresponding to two delayed and spatially inverted pulses. Likewise, accuracy in estimation of spatial chirp is improved by using spatially resolved spectral trace of two spatially inverted pulses, as errors due to accidental improper positioning of either grating of spectrograph or CCD detector are avoided. Sensitivities and accuracies of the two methods are compared in different experimental situations. Estimated pulse parameters are found in close accordance with respective theoretical values.

Scanning spectrometer/monochromator for a wavelength range of 50 – 330 Å

A flat-field scanning spectrometer/monochromator of the Hettrick – Underwood type is implemented for a wavelength range λ ≈ 50 – 330 Å. The optical arrangement of the spectrograph comprises a focusing spherical (R = 6000 mm) mirror, mounted at a grazing angle of 8.34 °, and a grazing-incidence plane varied line-space (VLS) grating operating for a constant deflection angle of 16.68 °. The entrance and output slits of the instrument are immobile, and the focal distance varies only slightly over its operating spectral range. The short-wavelength boundary of the operating range is determined by the spectral source brightness and the reflection coefficients of the grating and the mirror rather than by defocusing. Laser-produced plasma spectra excited by a focused laser beam (0.5 J, 8 ns, 1.06 μm) are recorded. A spectral resolving power λ/δλ = 1300 is demonstrated at a wavelength of 182 Å. The configuration of the instrument of this type is suited to soft X-ray reflectometry and metrology with the use of laser-plasma and synchrotron radiation sources, and is perfectly compatible with modern CCD detectors.

Next-generation telescopes with curved focal surface for ultralow surface brightness surveys

ABSTRACT In spite of major advances in both ground- and space-based instrumentation, the ultralow surface brightness Universe (ULSB) still remains a largely unexplored volume in observational parameter space. ULSB observations provide unique constraints on a wide variety of objects, from the Zodiacal light all the way to the optical cosmological background radiation, through dust cirri, mass-loss shells in giant stars, LSB galaxies and the intracluster light. These surface brightness levels (&gt;28–29 mag arcsec−2) are observed by maximizing the efficiency of the surveys and minimizing or removing the systematics arising in the measurement of surface brightness. Based on full-system photon Monte Carlo simulations, we present here the performance of a ground-based telescope aimed at carrying out ULSB observations, with a curved focal surface design. Its off-axis optical design maximizes the field of view while minimizing the focal ratio. No lenses are used, as their multiple internal scatterings increase the wings of the point spread function (PSF), and the usual requirement of a flat focal plane is relaxed through the use of curved CCD detectors. The telescope has only one unavoidable single refractive surface, the cryostat window, and yet it delivers a PSF with ultracompact wings, which allows the detection, for a given exposure time, of surface brightness levels nearly three orders of magnitude fainter than any other current telescope.