Two-dimensional visualization of cluster beams by microchannel plates Khoukaz, A.; Bonaventura, D.; Grieser, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2014, Letnik:
735
Journal Article
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An advanced technique for a two-dimensional real time visualization of cluster beams in a vacuum as well as of the overlap volume of cluster beams with particle accelerator beams is presented. The ...detection system consists of an array of microchannel plates (MCPs) in combination with a phosphor screen which is read out by a CCD camera. This setup together with the ionization of a cluster beam by an electron or ion beam allows for spatial resolved investigations of the cluster beam position, size, and intensity. Moreover, since electrically uncharged clusters remain undetected, the operation in an internal beam experiment opens the way to monitor the overlap region and thus the position and size of an accelerator beam crossing an originally electrically neutral cluster jet. The observed intensity distribution of the recorded image is directly proportional to the convolution of the spatial ion beam and cluster beam intensities and is by this a direct measure of the two-dimensional luminosity distribution. This information can directly be used for the reconstruction of vertex positions as well as for an input for numerical simulations of the reaction zone. The spatial resolution of the images is dominated by the granularity of the complete MCP device and was found to be in the order of sigma approximately 100 mu m.
MAGIX is a planned experiment that will be implemented at the upcoming accelerator MESA in Mainz. Due to its location in the energy-recovering lane of the accelerator beam-currents up to 1mA with a ...maximum energy of 105 MeV will be available for precision experiments. MAGIX itself consists of a jet-target and two magnetic spectrometers. Inside the spectrometers GEM-based detectors will be used in the focal plane for track reconstruction. The design goals for the detector modules are a spatial resolution of 50 um, a size of 1.20 m x 0.3 m and a minimal material budget. To accomplish these goals we started developing several GEM-prototypes to study different behaviors and techniques to optimize the final detector design. The GEM foils used are provided by CERN and are trained, stretched and framed in our laboratory. The readout is done with an SRS based system. In this contribution the requirements, achievements and the ongoing developments are presented.
To investigate the risk of arsenic exposure from a coal-burning power plant in Slovakia on nonmelanoma skin cancer (NMSC) development, a 1996–1999 population-based case-control study was conducted ...with 264 cases and 286 controls. Exposure assessment was based on residential history and annual emissions (Asres1, Asres2) and on nutritional habits and arsenic content in food (Asnut1, Asnut2). Asres1 was assessed as a function of the distance of places of residence to the plant. Asres2 additionally considered workplace locations. Asnut1 was used to calculate arsenic uptake by weighting food frequencies with arsenic concentrations and annual consumption of food items. Asnut2 additionally considered consumption of local products. Age- and gender-adjusted risk estimates for NMSC in the highest exposure category (90th vs. 30th percentile) were 1.90 (95% confidence interval (CI): 1.39, 2.60) for Asres1, 1.90 (95% CI: 1.38, 2.62) for Asres2, 1.19 (95% CI: 0.64, 2.12) for Asnut1, and 1.83 (95% CI: 0.98, 3.43) for Asnut2. No interaction was found between arsenic exposure and dietary and residential data. Other plant emissions could have confounded the distance-based exposure variables. Consumption of contaminated vegetables and fruits could be confounded by the protective effects of such a diet. Nevertheless, the authors found an excess NMSC risk for environmental arsenic exposure.
PANDA (anti-Proton ANnihiliation at DArmstadt) is planned to be one of the four main experiments at the future international accelerator complex FAIR (Facility for Antiproton and Ion Research) in ...Darmstadt, Germany. It is going to address fundamental questions of hadron physics and quantum chromodynamics using cooled antiproton beams with a high intensity and and momenta between 1.5 and 15 GeV/c. PANDA is designed to reach a maximum luminosity of 2x10^32 cm^2 s. Most of the physics programs require an excellent particle identification (PID). The PID of hadronic states at the forward endcap of the target spectrometer will be done by a fast and compact Cherenkov detector that uses the detection of internally reflected Cherenkov light (DIRC) principle. It is designed to cover the polar angle range from 5{\deg} to 22{\deg} and to provide a separation power for the separation of charged pions and kaons up to 3 standard deviations (s.d.) for particle momenta up to 4 GeV/c in order to cover the important particle phase space. This document describes the technical design and the expected performance of the novel PANDA Disc DIRC detector that has not been used in any other high energy physics experiment (HEP) before. The performance has been studied with Monte-Carlo simulations and various beam tests at DESY and CERN. The final design meets all PANDA requirements and guarantees suffcient safety margins.
To assess the arsenic exposure of a population living in the vicinity of a coal-burning power plant with high arsenic emission in the Prievidza District, Slovakia, 548 spot urine samples were ...speciated for inorganic As (Asinorg), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and their sum (Assum). The urine samples were collected from the population of a case-control study on nonmelanoma skin cancer (NMSC). A total of 411 samples with complete As speciations and sufficient urine quality and without fish consumption were used for statistical analysis. Although current environmental As exposure and urinary As concentrations were low (median As in soil within 5 km distance to the power plant, 41 μg/g; median urinary Assum, 5.8 μg/L), there was a significant but weak association between As in soil and urinary Assum(r = 0.21, p < 0.01). We performed a multivariate regression analysis to calculate adjusted regression coefficients for environmental As exposure and other determinants of urinary As. Persons living in the vicinity of the plant had 27% higher Assumvalues (p < 0.01), based on elevated concentrations of the methylated species. A 32% increase of MMA occurred among subjects who consumed homegrown food (p < 0.001). NMSC cases had significantly higher levels of Assum, DMA, and Asinorg. The methylation index Asinorg/( MMA+ DMA) was about 20% lower among cases (p < 0.05) and in men (p < 0.05) compared with controls and females, respectively.
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Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Phys. Rev. D 95, 032003 (2017) The exclusive charmonium production process in $\bar{p}p$ annihilation with
an associated $\pi^0$ meson $\bar{p}p\to J/\psi\pi^0$ is studied in the
framework of QCD ...collinear factorization. The feasibility of measuring this
reaction through the $J/\psi\to e^+e^-$ decay channel with the PANDA
(AntiProton ANnihilation at DArmstadt) experiment is investigated. Simulations
on signal reconstruction efficiency as well as the background rejection from
various sources including the $\bar{p}p\to\pi^+\pi^-\pi^0$ and $\bar{p}p\to
J/\psi\pi^0\pi^0$ reactions are performed with PandaRoot, the simulation and
analysis software framework of the PANDA experiment. It is shown that the
measurement can be done at PANDA with significant constraining power under the
assumption of an integrated luminosity attainable in four to five months of
data taking at the maximum design luminosity.
Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of ...hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (\(\pi N\)) TDAs from \(\bar{p}p \to e^+e^- \pi^0\) reaction with the future \={P}ANDA detector at the FAIR facility. At high center of mass energy and high invariant mass squared of the lepton pair \(q^2\), the amplitude of the signal channel \(\bar{p}p \to e^+e^- \pi^0\) admits a QCD factorized description in terms of \(\pi N\) TDAs and nucleon Distribution Amplitudes (DAs) in the forward and backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring \(\bar{p}p \to e^+e^- \pi^0\) with the \={P}ANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. \(\bar{p}p \to \pi^+\pi^- \pi^0\) were performed for the center of mass energy squared \(s = 5\) GeV\(^2\) and \(s = 10\) GeV\(^2\), in the kinematic regions \(3.0 < q^2 < 4.3\) GeV\(^2\) and \(5 < q^2 < 9\) GeV\(^2\), respectively, with a neutral pion scattered in the forward or backward cone \(| \cos\theta_{\pi^0}| > 0.5 \) in the proton-antiproton center of mass frame. Results of the simulation show that the particle identification capabilities of the \={P}ANDA detector will allow to achieve a background rejection factor of \(5\cdot 10^7\) (\(1\cdot 10^7\)) at low (high) \(q^2\) for \(s=5\) GeV\(^2\), and of \(1\cdot 10^8\) (\(6\cdot 10^6\)) at low (high) \(q^2\) for \(s=10\) GeV\(^2\), while keeping the signal reconstruction efficiency at around \(40\%\). At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to \(2\) fb\(^{-1}\) of integrated luminosity. (.../...)
Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the ...proton form factors can be determined is estimated. The signal channel \(\bar p p \to e^+ e^-\) is studied on the basis of two different but consistent procedures. The suppression of the main background channel, \(\textit{i.e.}\) \(\bar p p \to \pi^+ \pi^-\), is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance.
This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a ...Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM-stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy-loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described.
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