Efficient Detector System Research Articles

Luminescent carbon nanodots based aptasensors for rapid detection of kanamycin residue

Despite the success in long-term storage of food and dietary products using antibiotics as supplements, enormous levels of their residues have remained as a significant health concern, leading to severe toxicity issues on consumption. Herein, we report an ultrasensitive and highly selective aptasensor based on carbon nanoparticles (CNPs) through a fluorescence-based aptamer-linked immunosorbent assay (FALIA) for rapid detection of kanamycin (KAA) residue. The fabricated CNP-aptasensor exhibited superior selectivity with exceptional photoluminescence properties. Under the optimal conditions, the linear equation of standard KAA solution was Y = −0.2279LogX+1.3648 (R = −0.9893) ranged from 10−4 to 10−7 ppb with excellent relative standard deviations (RSD) between 3.12 and 5.59 % (n = 3). Moreover, the limit of detection (LOD) was lower than 5.0 × 10−8 ppb. Together, the excellent recovery and significant efficacy in the rapid detection of antibiotics at a low level in milk indicate that this fabricated CNP-aptasensor has a great potential in the establishment of an efficient antibiotic detector system in food and other nutraceutical industries.

Clusters in neutron-rich light nuclei

Due to their high selectivity, transfer and sequential decay reactions are powerful tools for studies of both single particle (nucleon) and cluster states in light nuclei. Their use is particularly simple for investigations of α -particle clustering (because α -particle has J π =0 + , which simplifies spin and parity assignments to observed cluster states), but they are also easily applicable to other types of clustering. Recent results on clustering in neutron-rich isotopes of beryllium, boron and carbon obtained measuring the 10 B+ 10 B reactions (at 50 and 72 MeV) are presented. The highly efficient and segmented detector systems used, built from 4 Double Sided Silicon Strip Detectors (DSSSD) allowed detection of double and multiple coincidences and, in that way, studies of states populated in transfer reactions, as well as their sequential decay.

CCC-based muon telescope for examination of natural caves

Abstract. A portable cosmic muon detector has been developed for geophysical applications: searching for large scale underground rock/soil inhomogeneities and underground cavities. The designed muon telescope called a muon tomograph is based on the recently developed closed cathode chamber (CCC) technology, which provides a cheap, easy handling, portable, and power efficient detector system able to work even in extreme conditions (e.g. high humidity, low/high temperature). The muon telescope has a detection surface of approximately 0.1 m2 with a 10 mrad angular resolution. Tests have been performed in natural caves and artificial tunnel systems as well. In this paper a summary of the first results on tomographic cavities are presented and the geophysical and possible industrial use of the cosmic muon tomographic technology is indicated.

Measurements of Activation and Decay Heat Produced in Materials Irradiated with D-T Neutron and Comparison with EASY-2007 Code Predictions

Neutron activation of materials produces an energy release during the subsequent radioactive decay. In a fusion power plant this energy release is of the order of MWs. Accurate prediction of this decay heat is fundamental for the design of a fusion power plant, especially for the safety analysis. A very efficient detector system able to measure both electron and photon heats simultaneously and separately has been developed at ENEA Frascati and has been already used to validate the predictions of computer codes developed to calculate neutron activation energy release. In this paper we report measurements on some elements (tin, tantalum and lead) that have been irradiated with the D-T fusion neutrons produced by the Frascati Neutron Generator FNG. These elements could be present in ITER materials and give a significant contribution to the total radioactive inventory, especially if they produce long-live radionuclides. The scope of this study is to validate the general purpose code European Activation code System EASY-2007 comparing the results of the measurements with code predictions. The results are presented in terms of C/E (Calculation vs. Experiment) together with the associated uncertainties.

Micro-channel plate detector for ultra-fast relativistic electron diffraction

Using relativistic ultra-short electron beams to obtain single-shot diffraction patterns holds the promise to yield real-time resolution of atomic motion in an easily accessible environment, such as a university laboratory, at a fraction of the cost of fourth-generation X-ray sources. One of the main issues in bringing this technique to full maturity is the development of efficient detector systems to record the diffraction pattern using a few MeV electron beams. Low noise, high spatial resolution, and single-electron detection capability are all characteristics of an ideal detector. In this paper, we compare the performances of a traditional fluorescent phosphor screen with a detection system based on the micro-channel plate (MCP). Since MCPs are typically used with lower energy electron beams, these tests constitute one of the few experimental data points available on the use of these devices with MeV energy beams.

Investigation of scattering between mirror nucleiBe7andLi7

Angular distribution for $^{7}\mathrm{Be}+^{7}\mathrm{Li}$ elastic scattering has been measured using a $^{7}\mathrm{Be}$ radioactive beam at the Nuclear Science Center, New Delhi, at ${E}_{c.m.}=9.87$ and 8.87 MeV. A compact and highly efficient detector system in kinematic coincidence mode and an in-vacuum target transfer system have been developed to minimize contributions from unwanted channels. The angular ranges covered were ${\ensuremath{\theta}}_{c.m.}={42}^{\ifmmode^\circ\else\textdegree\fi{}}--{66}^{\ifmmode^\circ\else\textdegree\fi{}}$ and ${\ensuremath{\theta}}_{c.m.}={114}^{\ifmmode^\circ\else\textdegree\fi{}}--{138}^{\ifmmode^\circ\else\textdegree\fi{}}$. At the backward angles at both energies, the experimental angular distribution shows higher cross sections than the theoretical predictions for the direct elastic channel alone. The experimental data could be fitted with an isospin-dependent complex potential that is analogous to the Lane potential. A coupled-channel calculation with ground-state reorientation could also fit the data.

Measurement of Helicity-Dependent Photoabsorption Cross Sections on the Neutron from 815 to 1825 MeV

Helicity-dependent total photoabsorption cross sections on the deuteron have been measured for the first time at ELSA (Bonn) in the photon energy range from 815 to 1825 MeV. Circularly polarized tagged photons impinging on a longitudinally polarized LiD target have been used together with a highly efficient 4pi detector system. The data around 1 GeV are not compatible with predictions from existing multipole analyses. From the measured energy range an experimental contribution to the GDH integral on the neutron of [33.9 +/- 5.5(stat) +/- 4.5(syst)] microb is extracted.

Study of elastic scattering of mirror nuclei 7Be + 7Li

The angular distribution of 7 Be + 7 Li elastic scattering has been measured using 7 Be from the Radioactive beam at Nuclear Science Centre, New Delhi at E cm = 9.87 MeV. A compact and highly efficient detector system in kinematic coincidence mode and an in-vacuum target transfer system have been developed to minimise contributions from unwanted channels. The angular ranges covered were θ cm = 42°- 66°and θ cm = 114°- 138°. The experimental angular distribution shows higher cross sections than the theoretical predictions at the backward angles. The experimental data could be fitted with an isospin dependent complex potential that is analogous to the Lane potential.

Measurement of the 8Li( α, n) 11B reaction cross sections of astrophysical interest

An accurate exclusive measurement of the 8 Li( α , n) 11 B reaction cross sections has been carried out successfully by using a highly efficient detector system and high-purity low energy 8 Li-beam. The excitation function obtained with high statistics in the energy region from 0.9 to 2.7 MeV in the center-of-mass system is reported. The present cross sections show that the averaged ratio of total cross section to the inverted neutron capture cross section is 4 ∼ 5. Some details of the experimental method are also described.

Detector efficiency and signature efficiency in the study of exotic nuclei

The role of highly efficient detector systems and highly efficient signatures of structure in the study of exotic nuclei is discussed. The discovery of “critical point symmetries” in the study of phase transitional behavior in nuclei, with applications to unknown regions, is also discussed.

A highly efficient neutron time-of-flight detector for inertial confinement fusion experiments

We have developed the highly efficient neutron detector system MANDALA for the inertial-confinement-fusion experiment. The MANDALA system consists of 842 elements plastic scintillation detectors and data acquisition electronics. The detection level is the yield of 1.2×105 for 2.5 MeV and 1×105 for 14.1 MeV neutrons (with 100 detected hits). We have calibrated the intrinsic detection efficiencies of the detector elements using a neutron generator facility. Timing calibration and integrity test of the system were also carried out with a Co60 γ ray source. MANDALA system was applied to the implosion experiments at the GEKKO XII laser facility. The integrity test was carried out by implosion experiments.

Astrometry from Space: New Design of the GAIA Mission

An interferometric astrometric mission, aiming at accuracies at around the10 microarcsec level, was recommended as a high priority concept within thenew ESA Horizon 2000+ scientific programme. The original outline concept forsuch a mission, GAIA, presented its general feasibility but did not addressmany questions of implementation or optimisation. Another concept of aninterferometer for a scanning astrometric satellite is presented. It containsa simpler optical telescope and a more efficient detector system. The designutilizes the full resolution of all light in the dispersed fringes of aFizeau interferometer. A preliminary optimization of the satellite indicatesthat two telescope units with a baseline of 100 cm will achieve a precisionof 3, 8, 22, 68, 302 microarcsec for parallaxes of stars with V = 12, 14, 16, 18, 20 mag, respectively, from a 5 year mission. Simultaneousspectrophotometry of the entire spectrum of each star will be obtained with aresolution corresponding to intermediate band photometry. The expectedprecision of this photometry is about 0.003 mag for V = 16. The performance is good in crowded fields, at least up to one star per 5 arcsec2. A Hipparcos-type beam combiner of 150 cm width is placed in front of atelescope with 4 square apertures of 50 cm. The assumed focal length is f = 60 m and the field 0.5 degree diameter. The detector consists of CCDs used for time delayed integration (drift-scan.)

Fabrication and Testing of a Double Ionization Chamber for On-Line Tritium Production Rate Measurements and Comparison with the Standard Liquid-Scintillation Method

At the LOTUS facility, an extremely efficient on-line detector system, based on the detection of the charged particles associated with the [sup 6]Li(n,[alpha])t reaction, has been designed, fabricated, and tested. The system offers an interesting possibility for directly measuring the tritium production rate (TPR) at any experimental site. The charged particles emitted in opposite directions can be detected by a double parallel plate ionization chamber (DIC) configuration. The real events are identified by employing a coincidence circuit. The complete fabrication details, testing under different conditions, measurement of TPR, and its comparison with the liquid-scintillation method (LSM) are detailed. The DIC response to thermal neutrons agrees well with the theoretical calculations. Also, the detector system is insensitive to a contact gamma dose rate of 1.3 rem/h. The direct TPR measurements and the salient feature of higher efficiency in comparison with the LSM are demonstrated. The TPR determined by both methods are in excellent agreement. 14 refs., 11 figs., 1 tab.

RS/hyper: A Hypertext-Based Workstation for Reliable X-Ray Residual Stress Measurements

AbstractAdvances over the last ten years in computer automation and control, compact and portable x-ray sources, and reliable and efficient detector systems have allowed X-Ray Determination of Residual Stress (XRDRS) measurements to become a viable method of evaluating the state of stress in metals, alloys, and ceramics. However, problems associated with incorrect XRDRS equipment operation and poor experimental technique are prevelant in industry, necessitating better operator training and education. Therefore, an interactive computer workstation, called RS/hyper, was developed to lead the operator towards correct operating procedures and reliable experimental technique.Proper machine setup, machine maintenance, radiation safety, experimental technique, theoretical understanding, and limited data evaluation are presented in RS/hyper. Graphical aids are used extensively to avoid confusion and misinterpretation of theoretical concepts and equipment instructions. RS/hyper is interactive, allowing the user to learn about topics at a comfortable level of explanation. Compared to written texts and references, RS/hyper has been shown to reduce training and problem solving time by a factor of 16.RS/hyper will train novice users of XRDRS equipment so that the data acquired from such machines will be reliable in an industrial environment. Also, since the software educates the user, data will be more accurately represented before interpretation. The experienced user should find RS/hyper useful as a reference to XRDRS and related information.

Gamma-ray multiplicity distributions in 16O + 152Sm fusion near and below the Coulomb barrier

We have studied γ-ray multiplicity distributions for the system 16O + 152Sm at five beam energies in the range 60–80 MeV, near and below the Coulomb barrier. The data were obtained using a large array of γ-ray detectors and an efficient evaporation-residue detector system utilizing an electrostatic deflector. The data are in good agreement with predictions of angular momentum distributions calculated using a coupled-channels model incorporating the effects of deformation.

An Efficient Annular Dark-Field Detector Capable of Single-Electron Counting Adapted to a High-Resolution Field-Emission SEM

Various high resolution scanning electron microscopes (HRSEM) are now commercially available providing probe sizes in the range of 0.5 to 1.5 nm at 30 keV due to their field emission gun 1.2. Equipped with efficient detector systems (which collect different signals and applied to specifically prepared samples) HRSEM challenge the conventional transmission electron microscope (TEM) with high resolution surface images of biological specimens collecting secondary (SE) or backscattered (BSE) electrons. However, the yield of (SE) carrying high resolution information is rather small, i.e. the SE-I yield at 20 keV primary electron energy amounts to < 1% for the major elements (H; C; N; O; P) constituting biological matter. The yield of BSE is greater than the corresponding total SE yield (electron energy >15 keV), but BSE emerge due to high angle elastic scattering from a surface area with a diameter of typically 30% of the deepest electron penetration R (e.g. R≈10 μm for elements mentioned above at 30 keV).

Rapid Recording of Microdiffraction with a STEM Instrument

The optical system attached to our HB5 STEM instrument acts as an efficient two-dimensional detector system which allows microdiffraction patterns from regions 10Å or less in diameter to be recorded at TV rates. Replaying the patterns from single video-tape frames allows us to study transient phenomena and to overcome to some extent the limitations due to the mechanical and electrical instabilities which often induce relative movements of the electron beam and the specimen of the order of 1Å over periods of a fraction of a second.This rapid recording has made it possible for microdiffraction patterns to be obtained from regions of less than 20Å in diameter selected from images of a highly disordered kaolinite sample which is very sensitive to radiation damage. When the electron beam is stopped at a position chosen by a marker in the bright field image, the diffraction pattern fades out in about 0.1 secs, but several single frames of the videotape provide good records such as that of figure 1(a).

High-resolution radioisotopic measurements of calcium, strontium, and barium in heart.

A gamma-ray detector system used in conjunction with isolated vascularly perfused rabbit septa labeled with the Ca-like cations 85Sr and 133Ba has been developed to test the feasibility of constructing a considerably more efficient detector system capable of measuring the highly energetic (Emax congruent to 1.3 MeV) 47Ca radionuclide. In addition an experimental design has been developed to quantify, statistically, perturbations of total tissue Ca, Sr, or Ba should they occur. This project was undertaken because the severe attenuation by living tissue of the beta-emitting radionuclide 45Ca (Emax congruent to 250 keV) limits its usefulness as a Ca tracer during experiments in which total tissue Ca is being measured minute-by-minute by an external detector. Analyses of over 100 experiments conducted on 35Sr- and 133Ba-labeled rabbit septa indicate that a tissue-detector system can be developed having the capacity to resolve perturbations of as little as 2 mumol Ca/kg wet tissue at 1-min sampling times or 6 mumol Ca/kg wet tissue at 0.1-min sampling times.