The effects of cryocooler microphonics, EMI and temperature variations on bolometric detectors

The use of mechanical coolers for space-based infrared telescopes is becoming a reality with the development of the Planck spacecraft, which will obtain full sky maps of the temperature anisotropy and polarisation of the cosmic microwave background (CMB). The High Frequency Instrument is one of two instruments aboard Planck and will use 48 bolometric detectors operating at 0.1 K. We summarise the performance of the RAL 4 K Joule–Thomson (J–T) system which will precool these detectors, and describe integration aspects of the sensitive bolometric detectors with cryocoolers at system level, in particular the effects of cryocooler vibration, EMI and thermal fluctuations. Full understanding of these systematic sources of noise is critical to enable the microkelvin level scientific signals to be cleanly extracted from the raw data.     

Radiative ion-ion neutralization: a new gas-phase atmospheric pressure ion transduction mechanism

All atmospheric pressure ion detectors, including photo ionization detectors, flame ionization detectors, electron capture detectors, and ion mobility spectrometers, utilize Faraday plate designs in which ionic charge is collected and amplified. The sensitivity of these Faraday plate ion detectors are limited by thermal (Johnson) noise in the associated electronics. Thus approximately 10(6) ions per second are required for a minimal detection. This is not the case for ion detection under vacuum conditions where secondary electron multipliers (SEMs) can be used. SEMs produce a cascade of approximately 10(6) electrons per ion impinging on the conversion dynode. Similarly, photomultiplier tubes (PMTs) can generate approximately 10(6) electrons per photon. Unlike SEMs, however, PMTs are evacuated and sealed so that they are commonly used under atmospheric pressure conditions. This paper describes an atmospheric pressure ion detector based on coupling a PMT with light emitted from ion-ion neutralization reactions. The normal Faraday plate collector electrode was replaced with an electrode "needle" used to concentrate the anions as they were drawn to the tip of the needle by a strong focusing electric field. Light was emitted near the surface of the electrode when analyte ions were neutralized with cations produced from the anode. Although radiative-ion-ion recombination has been previously reported, this is the first time ions from separate ionization sources have been combined to produce light. The light from this radiative-ion-ion-neutralization (RIIN) was detected using a photon multiplier such that an ion mobility spectrum was obtained by monitoring the light emitted from mobility separated ions. An IMS spectrum of nitroglycerin (NG) was obtained utilizing RIIN for tranducing the mobility separated ions into an analytical signal. The implications of this novel ion transduction method are the potential for counting ions at atmospheric pressure and for obtaining ion specific emission spectra for mobility separated ions.     

Evaluation of 400 low background 10-in. photo-multiplier tubes for the Double Chooz experiment

The Double Chooz is a reactor neutrino experiment which measures the last unknown neutrino mixing angle θ₁₃. The Double Chooz experiment uses two identical detectors placed at sites far and near from Chooz reactor cores. The detector uses 390 low-background and high performance 10-in. Photo-Multiplier Tubes (PMTs) to detect scintillation light from gadolinium loaded liquid scintillator. In order to test and characterize the PMTs and to tune operation parameter, we developed two types of PMT test system and evaluated 400 PMTs before installation. Those PMTs fulfilled our requirements and half of them were installed in the far detector in 2009 and physics data have been successfully taken since 2011.     

Biomemory device composed of mutant azurin thin films modified by site-directed mutagenesis

A bioelectronic device composed of self-assembled mutant azurin thin films with memory function has been developed for molecular electronics. Azurin was recombined with a cysteine residue to enhance the stability of self-assembled protein on gold surface. The thin films of protein on gold substrate were investigated by surface plasmon resonance spectroscopy, scanning tunneling microscopy and Raman spectroscopy, respectively. The memory characteristics, including the “read”, “write” and “erase” functions of self-assembled azurin layer, were obtained with three distinct electrical states of azurin layers by cyclic voltammetry. These results show the proposed biomemory device as a step towards the protein based nanobiochip.     

Molecular weight dependence on bioavailability of FITC-dextran after administration of self-dissolving micropile to rat skin

Background: Self-dissolving micropiles (SDMPs) have been evaluated with macromolecular drugs like insulin and erythropoietin as a new percutaneous drug delivery system. To study the molecular weight dependence on the absorption of macromolecular drugs through the skin after administration of SDMPs, four kinds of SDMP were prepared using fluorescein isothiocyanate-labeled dextrans (FDs) having a molecular weight of 10, 20, 40, and 70 kDa. Method: In in vitro release experiments there were no significant differences on their release rates in the four SDMPs. The dependence of molecular weight of FD on the permeability coefficient was studied in the in vitro permeation experiment. Histological study on the skin after administration of FD SDMP (5.0 mg/kg) to rat was performed for 24 hours. In vivo experiment using rats resulted in slower absorption rate of FD-40 and FD-70 SDMP (5.0 mg/kg). Results: The permeability coefficient was 4.59, 4.69, 3.38, and 1.43 × 10^?4 cm/h for FD-10, 20, 40, and 70, respectively. Histological examination showed that yellow color was still observed at 6 h after administration of FD-40, and FD‐70 showed yellow color even at 24 h. Bioavailabilities of FDs from SDMP were 99.4 ± 6.93%, 88.3 ± 7.05%, 45.7 ± 4.77%, and 16.0 ± 1.15% for FD-10, 20, 40, and 70, and the dependency on molecular weight dependence was clearly observed. Conclusion: These observations supported that bioavailabilities of FD from SDMP decreased as the molecular weight of FD increased to more than 40 kDa.     

Silicon beam telescope for CMS detector tests

A beam telescope providing precision track measurements as reference for other detectors has been upgraded in the CERN H2 test beam. The apparatus was completely rebuilt from the detector wafers and front-end electronics to the data acquisition system. The new detector setup consists of eight 5.6×5.6 cm² sized DC coupled silicon microstrip detectors. Typical position resolution values of about 7.5 μm were measured. Details of the setup are described and results from the recent beam tests are reported.     

Evaluating formal properties of feature diagram languages

Feature diagrams (FDs) are a family of popular modelling languages, mainly used for managing variability in software product lines. FDs were first introduced by Kang et al. as part of the feature-oriented domain analysis (FODA) method back in 1990. Since then, various extensions of FODA FDs were devised to compensate for purported ambiguity and lack of precision and expressiveness. Recently, the authors surveyed these notations and provided them with a generic formal syntax and semantics, called free feature diagrams (FFDs). The authors also started investigating the comparative semantics of FFD with respect to other recent formalisations of FD languages. Those results were targeted at improving the quality of FD languages and making the comparison between them more objective. The previous results are recalled in a self-contained, better illustrated and better motivated fashion. Most importantly, a general method is presented for comparative semantics of FDs grounded in Harel and Rumpe's guidelines for defining formal visual languages and in Krogstie et al.'s semiotic quality framework. This method being actually applicable to other visual languages, FDs are also used as a language (re)engineering exemplar throughout the paper.     

Fractal study on collective evolution of short fatigue cracks under complex stress conditions

This paper proposes a Paris-type damage model to investigate the collective evolution of short fatigue cracks based on fractal theory. On the basis of experimentally determined images, the fractal dimensions (FDs) of rounded notched specimens’ surfaces are numerically calculated by using Otsu threshold segmentation and box-counting dimension method. The results show that FDs’ evolution presents “HILL” curves’ characteristics. The transition period between FD rapid growth stage and FD constant stage takes place at about 30% of fatigue life. The good match between experimental results and FEM analyses reveals the model can describe collective damage process caused by all fatigue cracks.     

Technology, weapons, and industrial development: The case of Israel

The impact of the indigenous design and production of technologically advanced weapons in industrializing states continues to be a subject of great interest and importance. To date, however, studies of this linkage have tended to be highly generalized and simplistic. Most use static models, which assume either that this investment tends to divert scarce resources from the task of “nation building,” or, at the other end of the spectrum, that such production “spills over” into other areas, providing an infrastructure for broader technological and managerial development. In this study, a relatively complex and dynamic model relating military production to economic and technological development is proposed. In examining the case of Israel, it is shown that military production passes through various stages and is composed of separate and usually diverse sectors, from electronics to metallurgy. At each level and for every sector, the type of technology required, and, thus, the investment, risks and the potential for spill-over are different. Although Israel is, in many cases, unusual, nevertheless the generalized model can serve as a basis for the investigation of other cases.     

Novel interferometric frequency discriminators for low noise microwave applications

New configurations of interferometric frequency discriminators (FD) for frequency stabilization of microwave oscillators are examined. The new FDs are arranged in single directional (SD) (patented), bidirectional (BD) (patent pending), and dual reflection (DR) (patent pending) configurations. In the SD configuration, the signals reflected off and transmitted through the resonator separately pass through different arms of the interferometer. In the BD configuration, microwaves pass in both directions through each arm of the interferometer. In the DR configuration, microwaves are reflected from the resonator as well as the compensating arm. The FD sensitivity is compared with that for the conventional interferometric FD and found to be 6 dB greater in the BD configuration. Because no circulator is required within the interferometer in either the BD or the DR FD, the discriminator's phase noise floor is not limited by the circulator contribution     

Simultaneous soft X-ray transmission and emission microscopy

Novel low-energy X-ray fluorescence (LEXRF) system based on a multiple Si drift detector (SDD) configuration has been developed and implemented in the European TwinMic X-ray microspectroscopy station operating at the Italian synchrotron radiation facility ELETTRA. The setup, hosting up to eight large-area SDDs with specially adapted readout electronics, has demonstrated excellent performance for elemental analysis in the 280–2200 eV photon energy range, which covers the K and L edges of light elements, starting from C. The great advantage is the simultaneous acquisition of LEXRF, absorption and phase contrast maps, providing complementary information on elemental composition and morphology of specimen at submicrometer length scales.     

Response of silicon-based linear energy transfer spectrometers: implication for radiation risk assessment in space flights

There is considerable interest in developing silicon-based telescopes because of their compactness and low power requirements. Three such telescopes have been flown on board the Space Shuttle to measure the linear energy transfer spectra of trapped, galactic cosmic ray, and solar energetic particles. Dosimeters based on single silicon detectors have also been flown on the Mir orbital station. A comparison of the absorbed dose and radiation quality factors calculated from these telescopes with that estimated from measurements made with a tissue equivalent proportional counter show differences which need to be fully understood if these telescopes are to be used for astronaut radiation risk assessments. Instrument performance is complicated by a variety of factors. A Monte Carlo-based technique was developed to model the behavior of both single element detectors in a proton beam, and the performance of a two-element, wide-angle telescope, in the trapped belt proton field inside the Space Shuttle. The technique is based on: (1) radiation transport intranuclear-evaporation model that takes into account the charge and angular distribution of target fragments, (2) Landau-Vavilov distribution of energy deposition allowing for electron escape, (3) true detector geometry of the telescope, (4) coincidence and discriminator settings, (5) spacecraft shielding geometry, and (6) the external space radiation environment, including albedo protons. The value of such detailed modeling and its implications in astronaut risk assessment is addressed.     

Light concentrators for the Sudbury Neutrino Observatory

There is an important and growing class of elementary particle detectors which are characterized by a large sensitive volume (thousands of tonnes), very low radioactive backgrounds, and rely on the emission of light for particle detection. Water Cherenkov detectors come into this category; they have a large mass of water as the sensitive medium. Particles are detected when they interact with the water and produce Cherenkov light, so detection efficiency relies on having a huge light sensitive area at the periphery of the detector. The most cost-effective way of achieving this is by placing light concentrators on large photomultiplier tubes (PMTs). This paper describes the work carried out on light concentrators for the PMTs in the Sudbury Neutrino Observatory, a 1000 tonne heavy water Cherenkov detector. We discuss the advantages of using light concentrators, summarize the optical theory of non-imaging light concentration, and describe in detail the development and manufacture of the concentrators themselves.     

Vapor–liquid equilibria of the (hexafluoroethane + 1,1,1-trifluoroethane) binary system from 258 to 343 K up to 3.89 MPa

Development of modern refrigeration systems is critical for the success of new global environmental protection efforts. The binary system of refrigerants: Hexafluoroethane (R116) + 1,1,1-trifluoroethane (R143a), has been studied with the aim of providing PTxy data. Isothermal vapor–liquid equilibrium data have been generated using the “static–analytic” method from 258 to 328 K at pressures from 0.39 to 3.89 MPa. The model composed of the Peng–Robinson equation of state, the Mathias–Copeman alpha function, the Wong–Sandler mixing rules and the NRTL cell theory is applied herein to correlate the data and calculate the critical line.     

Rationalizing the calibration method of reference telescopic radiation pyrometers

Conclusions An equation which was derived in this work provides with sufficient accuracy the relationship between the thermal emf and the measured radiation temperature for two types of TERA-50 radiation pyrometer telescopes.Optimum temperatures have been found for plotting a curve (2) through three points, at 600, 900 and 1200°C for telescopes type TERA-50/(600–1400°C), and at 1300, 1600 and 1900°C for telescopes type TERA-50/(1200–2500°C).Thus, it becomes possible to recommend a new and more efficient, three-point calibration technique for 2nd grade telescopes type TERA-50/(600–1400°C) and TERA-50/(1200–2500°C).     

The Utility of Signal-Detection Theory in the Analysis of Industrial Inspector Accuracy

In an experimental study of inspector accuracy utilizing industrial electronics inspectors as subjects, a visual, subject-paced task requiring a “yes-no” response was used. The results are thought to be generally applicable to visual inspection tasks, but may not be applicable in an inspection task requiring measurement, as in machine parts inspection. The major conclusion of the research is that signal-detection measures are more useful in performance evaluation than are other available measures, because they not only relate performance to payoff, but indicate the magnitude and direction of improvement required.     

On control strategies in a multi-stage production system

A multi-stage production system is composed of a set of stations, each station performing a given task, and a set of vehicles, each vehicle moving between two successive stations. A station can choose a buffer or a kanban mechanism for controlling the work-in-process (WIP) in the station. A vehicle can choose a push or a pull policy for carrying parts from its upstream station to its downstream station. A control strategy is formed by combining the WIP mechanisms adopted in all stations and the carrying policies employed by all vehicles. The production system is modelled as a queuing system. Some structural properties of performance measures are characterized. We develop a decomposition approach for large systems, which performs very well. We determine the optimal numbers of buffers or kanbans at all stations in the design period, and the optimal control strategy during operation. Many numerical computations are given for evaluating the efficiencies of the decomposition approach and optimization methods, and further providing some intuitions and insights.     

Cryogenic Design of the Setup for MARE-1 in Milan

A large worldwide collaboration is growing around the project of Micro-calorimeter Arrays for a Rhenium Experiment (MARE) for a direct calorimetric measurement of the neutrino mass. To validate the use of cryogenic detectors by checking the presence of unexpected systematic errors, two first experiments are planned using the available techniques composed of arrays of 300 detectors to measure 10¹⁰ events in a reasonable time of 3 years (step MARE-1) to reach a sensitivity on the neutrino mass of ∼2 eV/c². Our experiment in Milan is based on compensated doped silicon implanted thermistor arrays made in NASA/GSFC and on AgReO₄ crystals. We present here the design of the cryogenic system that integrates all the requirements for such experiment (electronics for high impedances, low parasitic capacitances, low micro-phonic noise).     

The Effect of the Coefficient of Variation of Operation Times on the Allocation of Storage Space in Production Line Systems

This paper studies the effect of the coefficient of variation of operation times on the optimal allocation of storage space in production line systems. The operation times at each station are modelled by a two-stage Coxian distribution. This work extends the results of our previous study of the storage allocation problem with exponentially distributed operation times. Interpreting Stage 1 of the two-stage Coxian distribution as the normal service for an item at a station and Stage 2 as down time at the station, our model can also be used to study the effect of breakdowns on the allocation of storage space in production line systems. The results show that the “bowl effect” whereby the center stations should be given preferential treatment becomes more pronounced with higher variability in the operation times. Another general conclusion is that the overall optimal storage allocation commonly follows a “storage bowl phenomenon” whereby the allocation of buffer storage space fits an inverted bowl pattern when the total storage space is also a decision variable     

CHICSi—a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. I. General structure, mechanics and UHV compatibility

CELSIUS Heavy-Ion Collision Silicon detector system (CHICSi) is a large solid angle, barrel-shaped detector system, housing up to 600 detector telescopes arranged in rotational symmetry around the beam axis. CHICSi measures charged particles and fragments from nuclear reactions. It operates at internal targets of storage rings. In order to optimize space and momentum-space coverage and minimize the low-energy detection limits, CHICSi is designed for use in ultra-high vacuum (UHV, 10⁻⁸ Pa) inside a cluster-jet target chamber. This calls for materials in mechanical support, detectors, Very Large Scale Integrated (VLSI) electronics, connectors, cables and other signal transport devices with very low outgassing. Two auxiliary detector systems, which will operate in coincidence with CHICSi, a heavy-recoil, time-of-flight system (HR-TOF) also placed inside the target chamber and a projectile fragmentation wall (PF-WALL) located outside the chamber, have also been constructed. In total, this combined system registers more than 80% of all charged particles and fragments from typical heavy-ion reactions at energies of a few hundreds of MeV per nucleon.