External Facility Research Articles

Nuclear stopping and collective flow in CSR/LanZhou energy region

Nuclear stopping and collective flow for two pairs of symmetric colliding nuclei: 238U+238U and 129Xe+129Xe, which are proposed to be accelerated on Cooling Storage Ring (CSR), External Target Facility (ETF), LanZhou, China, are studied by a hadronic transport model ART1.0. The incident beam energy of Uranium and Xenon can be delivered up to 520 MeV/nucleon and 900MeV/nucleon, respectively. At this CSR energy region, the hot, dense nuclear matter are thought to be obtained in the lab, which is an idea circumstance to study the nuclear equation of state (EoS). As deformation of the Uranium nuclei, it is predicted that significant large baryon density in the tip-tip U+U collision patterns and the large elliptic flow in body-body collision pattern are both avail to study the nuclear EoS.

Is PIXE still a useful technique for the analysis of atmospheric aerosols? The LABEC experience

AbstractAt the 3‐MV Tandetron accelerator of LABEC (INFN) an external beam facility is fully dedicated to particle‐induced X‐ray emission (PIXE) and particle‐induced γ‐ray emission (PIGE) measurements of atmospheric aerosol elemental composition. All the elements with Z > 10 are simultaneously detected by PIXE in a few minutes and an automatic system for positioning, changing and scanning of the samples allows the analysis of the aerosol collected by different kinds of devices: long series of daily PMX samples can be measured in short times, as well as size‐segregated and high time‐resolution aerosol samples. Thanks to the capability of detecting all the crustal elements, PIXE‐PIGE analyses are unrivalled in the study of mineral dust: as a consequence, they are very effective in the study of natural aerosols, like, for example, mineral dust archived in polar ice cores (for environmental and paleoclimatic studies) and Saharan‐dust intrusions. Among the detectable elements, there are also important markers of anthropogenic sources, which allow effective source apportionment studies in polluted urban environments. Examples regarding recent monitoring campaigns, performed in urban and remote areas, both on a daily basis and with high‐time resolution (hourly samples), are presented to evidence how PIXE can still provide unique information in aerosol studies or can play a complementary role to X‐ray fluorescence or induced coupled plasma mass spectroscopy analysis. Copyright © 2011 John Wiley & Sons, Ltd.

Hearing Apparatus with Status Signal Facility and Corresponding Method

Status changes in a hearing apparatus and in particular a hearing device should be able to be transmitted to an external data processing facility in a more rapid manner. For this purpose, provision is made for the hearing apparatus to comprise a sensor facility to capture a status of a component of the hearing apparatus. Furthermore, a status signal facility is integrated into the hearing apparatus, said status signal facility being connected to the sensor facility and being able to be used to automatically transmit a signal to the external data processing facility, when a change in the status occurs. The status of the hearing apparatus need thus not be continually queried, but a corresponding signal is actively sent outwards in the event of a status change. The battery service life of a hearing device can hereby be increased for instance.

Design studies on the 4π γ-ray calorimeter for the ETF experiment at HIRFL-CSR

A high detection efficiency calorimeter which is used to detect γ-rays with energies from 1 MeV up to 10 MeV as well as light charged particles has been proposed. Design of the geometry, results of the crystal tests and Monte Carlo simulations are presented in this paper. The simulation results confirm that the calorimeter can obtain high detection efficiency and good energy resolution with the current designed geometry. And the calorimeter is competent for the future External Target Facility (ETF) experiments.

Expanding the Range of Applications for the Plasma-Enhanced Deposition of Barrier Coatings

Having worked intensely on plasma-assisted barrier coating (plasma enhanced chemical vapor deposition, PECVD) of polymers, a technique already used commercially to enhance shelf-life performance of PET bottles, for the last two decades, it seemed to be obvious to investigate the transfer of this existing technique to novel beverage materials such as PLA and PP. As a result of their high oxygen and carbon dioxide permeability the market potential of PP and PLA is still restricted in the beverage packaging sector. On the one hand, the use of plasma coatings to improve the barrier properties of these materials shows advantages. For example, these coatings are less likely to interfere with PLA-bottle biodegradability. On the other hand, materials such as PP and PLA put higher demands on plasma coating processes due to their different surface properties that make it much more difficult to establish an adequate adhesion between coating and bulk material and their increased sensitivity to high temperature. By using a pre-treatment specific to the materials, we succeeded in applying effective barrier coatings by plasma polymerization using both hydrocarbons as well as silicon organic monomers. For PLA the pre-treatment process can be integrated directly into the plasma polymerization process, whereas for PP it was necessary to use a LF-plasma in an external facility to enable a good coating adhesion. The barrier properties against oxygen could be increased by a factor of about 12 for PP and 4 for PLA. Hydrocarbon-based coatings proved to be more effective compared to HMDSO-based coatings. These first evaluations show that it is possible to raise the barrier performance of PP and PLA bottles to match the levels obtained with uncoated monolayer PET types. Our current research concentrates on improving the processes in order to increase the barrier performance and the efficiency of the process.

Access to financing and firm growth

Why do some firms grow faster than others? Although various observed and unobserved aspects of firms have been suggested as potential drivers of firm heterogeneity, economists disagree sharply on the role of financial structure in influencing firm growth. In this paper, I use a sample of quoted and unquoted firms to show that the effect of financial structure on firm growth is statistically significant and quantitatively important. In the presence of external financing constraints, firms rely more on internal funds to finance growth, but the effect of internal financing on firm growth decreases with an increase in the firm’s access to an external bank credit facility. As the external financing constraint is alleviated, the firm relies less on internal funds and switches to external financing as the primary source of financing for its growth. This pattern of transition between internal and external financing is particularly pronounced in small unquoted firms (conditional on their survival). These results suggest a real effect of financial structure on growth via the channel of an external financing constraint.

External scanning micro-PIXE for the characterization of a polycapillary lens: Measurement of the collected X-ray intensity distribution

Abstract We developed a PIXE detection system for the analysis of medium-light elements which exploits a weakly focusing polycapillary lens for the transmission of the X-rays emitted from the target material to a Silicon Drift Detector. The polycapillary lens efficiently collects X-rays, while prevents back-scattered protons from impinging on the detector chip, thus avoiding electronics perturbation and consequent quality loss of PIXE spectra. The system is optimized for the detection of X-rays in the energy range 1–10 keV, when the emission from the target is induced by MeV proton beams with size of the order of a few hundreds of micrometers. This work reports the results of the lens characterization in terms of X-ray collection spot, i.e. the area of the sample actually “seen” by the lens, and its dependence on the X-ray energy. The lens properties have been measured using the external scanning microbeam facility of the Tandetron accelerator at LABEC-INFN in Florence. The detection system was used to detect X-rays from a set of pure elemental standards with an incident 3 MeV proton beam focused to a size of about 30 μm scanning an area of 1.9 × 1.6 mm 2 . By measuring the spatial distribution of characteristic X-rays from each given material, the collection profile of the lens at the corresponding X-ray energy was obtained. Using several standards, the behaviour throughout the range 1–10 keV was examined. The sensitivity of the lens collection profile on the lens-sample out-of-focus distance was also investigated.

Studies of timing properties for a TOF counter at an external target facility

Timing and amplitude properties of a prototype scintillator TOF counter at an external target facility are studied with a cosmic rays test. The dependence of signal pulse height and time resolution on the coordinate along the scintillator TOF counter is investigated with two different discriminators. A time resolution of 165 ps can be achieved at the center of the counter with a constant fraction discriminator. Time resolution better than 150 ps is obtained at the center with a leading edge discriminator after time walk correction is applied for off-line analysis.

Studies of a scintillator-bar detector for a neutron wall at an external target facility

To achieve a better time resolution of a scintillator-bar detector for a neutron wall at the external target facility of HIRFL-CSR, we have carried out a detailed study of the photomultiplier, the wrapping material and the coupling media. The timing properties of a scintillator-bar detector have been studied in detail with cosmic rays using a high and low level signal coincidence. A time resolution of 80 ps has been achieved in the center of the scintillator-bar detector.

Differential and scanning-mode external PIXE for the analysis of the painting “Ritratto Trivulzio” by Antonello da Messina

Extensive PIXE investigations have been performed at the LABEC accelerator laboratory in Florence on the painting “Ritratto Trivulzio” by Antonello da Messina, one of the great Italian masters of XV Century and a pioneer in modern oil painting. It is well known that a complete and unambiguous characterisation of materials in paintings is often difficult, owing to their complex structure. For the “Ritratto Trivulzio”, the combination of advanced variants of PIXE, such as differential and scanning-mode analysis, provided a relevant contribution to the characterisation of paint layers, in terms of composition and structure, in a totally non-invasive and non-destructive way. Single-spot mode PIXE with external proton beams of about half millimetre diameter was first used for a general characterisation of different areas of the painting. Differential PIXE performed in many spots led to reconstruct the sequence of paints employed by the artist and to estimate in some cases the local paint layer thickness. A second run carried out with the external scanning microbeam facility, using a 3 MeV proton beam of about 80 μm size, was then crucial to clarify some issues raised by the first analysis. In particular, elemental maps from selected areas helped to understand the way some colour shades had been obtained on the red mantle of the portrayed gentleman, using different pigments irregularly distributed on the surface.

The ionoluminescence apparatus at the LABEC external microbeam facility

In this paper, we describe the main features of the ionoluminescence (IL) apparatus recently installed at the external scanning microbeam facility of the 3MV Tandetron accelerator of the INFN LABEC Laboratory in Firenze. The peculiarity of this IL set-up resides in the fact that the light produced by the ion irradiation of the specimen is collected by a bifurcated optical fiber, so that photons are shunted both to a CCD spectrometer, working in the 200–900nm wavelength range, and to a photomultiplier (PMT). The accurate focusing of the optical system allows high photon collection efficiency and this results in rapid acquisition of luminescence spectra with low ion currents on luminescent materials; simultaneously, luminescence maps with a spatial resolution of 10μm can be acquired through the synchronization of PMT photon detection with the position of the scanning focused ion beam. An optical filter with a narrow passband facing the photomultiplier allows chromatic selectivity of the luminescence centres.The IL apparatus is synergistically integrated into the existing set-up for ion beam analyses (IBA). The upgraded system permits simultaneous IL and PIXE/PIGE/BS measurements. With our integrated system, we have been studying raw lapis lazuli samples of different known origins and precious lapis lazuli artworks of the Collezione Medicea of Museum of Natural History, University of Firenze, aiming at characterising their composition and provenance.

Scanning-PIXE analysis of gold lace embroideries in a relic of St. Francis

In this work, we describe the compositional analysis performed by scanning-mode PIXE on the metal threads of a XIII century embroidery. The precious work analysed is the pillow-case used to cover the pillow, on which – according to tradition – St. Francis of Assisi was resting his head when he died. Measurements were performed in order to characterise the embroideries of the two sides and the passementerie in the lateral hems. Several areas, each of the order of two square millimetres, were scanned with a 3MeV proton external beam of 20μm size on target, using the external micro-beam facility of our laboratory, with list-mode acquisition. Analysis of elemental maps and spectra from selected homogeneous sub-areas allowed us to extract the quantitative composition of the gilded tape and estimates of its thickness.

Analysis of ancient embroideries by IBA techniques

Ion beam analysis (IBA) techniques are often used to study works of art, mainly for their non-destructive character. In these techniques, products of interactions between beams and targets are exploited to determine the elemental composition of the sample surface down to depths from few micrometres to hundreds of micrometres, depending on incident particles, their energy and target material.For samples with surface inhomogeneities, information about elemental distribution can be essential to discriminate contributions from different areas. At the authors’ laboratory in Florence (LABEC), the external scanning proton microprobe facility — installed on a beam line of the 3 MV Tandem Accelerator — allows samples to be analysed in atmosphere, with spatial resolution down to around micrometres, and to extract elemental maps from the investigated areas.Recently, there has been the opportunity of analysing a ‘gold lace embroidery’ (using silk threads, spiral wrapped by a sort of miniature golden tape) after a cartoon by Raffaellino del Garbo (the fifteenth–sixteenth centuries).

Recent developments of ion beam induced luminescence at the external scanning microbeam facility of the LABEC laboratory in Florence

A new ionoluminescence (IL) apparatus has been successfully installed at the external scanning microbeam facility of the 3 MV Tandetron accelerator of the INFN LABEC in Firenze; the apparatus for photon detection has been fully integrated in the existing ion beam analysis (IBA) set-up, for the simultaneous acquisition of IL and PIXE/PIGE/BS spectra and maps.The potential of the new set-up is illustrated in this paper by some results extracted by the analysis of art objects and advanced semiconductor materials. In particular, the adequacy of the new IBA set-up in the field of cultural heritage is pointed out by the coupled PIXE/IL micro-analysis of a lapis lazuli stone; concerning applications in material science, IL spectra from a N doped diamond sample were acquired and compared with CL analyses to evaluate the relevant sensitivities and the effect of ion damage.

Stopping effects in U+U collisions with a beam energy of 520 MeV/nucleon

A relativistic transport model (ART1.0) is applied to simulate the stopping effects in tip-tip and body-body U+U collisions, at a beam kinetic energy of 520 MeV/nucleon. Our simulation results have demonstrated that both central collisions of the two extreme orientations can achieve full stopping and also form a bulk of hot, dense nuclear matter with a sufficiently large volume and long duration, because of the largely deformed uranium nuclei. The nucleon sideward flow in the tip-tip collisions is nearly three times larger than that in body-body ones at the normalized impact parameter b/b{sub max}<0.5, and that the body-body central collisions have a large negative nucleon elliptic flow v{sub 2}=-12% in contrast to zero in tip-tip ones. Thus the extreme circumstance and the novel experimental observables in tip-tip and body-body collisions can provide a good condition and sensitive probe for studying the nuclear EoS, respectively. The cooling storage ring (CSR) external target facility (ETF) to be built at Lanzhou, China, delivering a uranium beam up to 520 MeV/nucleon is expected to make a significant contribution to exploring the nuclear equation of state (EoS)

A revised method to assess intensive care unit clinical performance and resource utilization*

In 1994, Rapoport et al. published a two-dimensional graphical tool for benchmarking intensive care units (ICUs) using a Mortality Probability Model (MPM0-II) to assess clinical performance and a Weighted Hospital Days scale (WHD-94) to assess resource utilization. MPM0-II and WHD-94 do not calibrate on contemporary data, giving users of the graph an inflated assessment of their ICU's performance. MPM0-II was recently updated (MPM0-III) but not the model for predicting resource utilization. The objective was to develop a new WHD model and revised Rapoport-Teres graph. Multicenter cohort study. One hundred thirty-five ICUs in 98 hospitals participating in Project IMPACT. Patients were 124,855 MPM0-II eligible Project IMPACT patients treated between March 2001 and June 2004. None. WHD was redefined as 4 units for the first day of each ICU stay, 2.5 units for each additional ICU day, and 1 unit for each non-ICU day after the first ICU discharge. Stepwise linear regression was used to construct a model to predict ICU-specific log average WHD from 39 candidate variables available in Project IMPACT. The updated WHD model has four independent variables: percent of patients dying in the hospital, percent of unscheduled surgical patients, percent of patients on mechanical ventilation within 1 hr of ICU admission, and percent discharged from the ICU to an external post-acute care facility. The first three variables increase average WHD and the last decreases it. The new model has good performance (R = 0.47) and, when combined with MPM0-II, provides a well-calibrated Rapoport-Teres graph. A new WHD model has been derived from a large, contemporary critical care database and, when used with MPM0-III, updates a popular method for benchmarking ICUs. Project IMPACT participants will likely perceive a decline in their ICU performance coordinates due to the recalibrated graph and should instead focus on their unit's performance relative to their peers.

The new target chamber at LIPSION: The new translation stage and goniometer and the new irradiation platform for single cell experiments

A new target chamber as well as a new 7-axes translation stage with goniometer will shortly be implemented at the LIPSION nanoprobe in Leipzig. This new stage should enable linear motion as well as rotary motion with high precision, positioning accuracy and repeatability. These different features have been investigated online as well as offline, with encouraging results. Along with the new equipment, new software is also being developed, to provide stage control running over network. These software developments, including a graphical user interface, will also be described. As part of the new target chamber, a new external beam facility and irradiation platform for single ion experiments on single living cells is being assembled. A detailed description of the new cell irradiation platform, including beam extraction, new cell dishes, and cell recognition aspects will be given. It will be shown that the possibility of offline cell recognition, possibly using a differential interference contrast microscope, is an option.

Inventory and Production Decisions for an Assemble-to-Order System with Uncertain Demand and Limited Assembly Capacity

This paper considers an inventory and production-planning problem for a contract manufacturer who anticipates an order of a single product, but with uncertain quantity. To meet the challenges of long component procurement lead times and limited assembly capacity, which may render production time insufficient to assemble total order quantity, the manufacturer may need to procure components or even assemble some quantities of the final product before receiving the confirmation of the actual order quantity. We present profit-maximization models that make optimal inventory and production decisions in the above assemble-to-order environment. We also consider the option of outsourcing, so that the manufacturer can outsource part of his production to an external facility that also has limited capacity. We establish structural properties of optimal solutions and develop efficient solution procedures for the proposed problems. We also provide sensitivity analysis of the optimal decisions, and some managerial insights.

The visigothic treasure of Torredonjimeno (Jaén, Spain): A study with IBA techniques

The visigothic treasure of Torredonjimeno (Jaén, Spain) was found by chance in the year 1926 buried in an olive grove. The finding consisted of some hundreds fragments of gold objects and gems coming from several votive crowns and crosses, some of them belonging to an unidentified visigothic king. The treasure may belong chronologically to the same period as the Guarrazar treasure or, possibly, to a somewhat later time, but the pieces are fragmented and of less technological workmanship than the latter. This is the reason why the Torredonjimeno treasure has not attracted as much attention from archeologists and art historians as that from Guarrazar. On the occasion of an exhibition showing together all the objects of the treasure, it is normally kept in three different museums in Barcelona, Cordoba and Madrid, a number of pieces were analyzed, using PIXE, PIGE and RBS, at the external microbeam facility installed at the Center for Micro-Analysis of Materials.

The new external beam facility for environmental studies at the Tandetron accelerator of LABEC

At the new 3MV Tandetron accelerator of the LABEC laboratory of INFN in Florence, an external beam facility fully dedicated to measurements of elemental composition of atmospheric aerosol has been installed. The experimental set-up hitherto used for this kind of applications has been upgraded with the introduction of a silicon drift detector and of a beam current monitor system based on the backscattering of protons on the extraction window. The new facility will be presented, together with some methodological results obtained so far for the analysis of airborne particulate matter samples collected on quartz fiber filters.