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Sample records for electron multiplier gem

  1. Gaseous Electron Multiplier (GEM) Detectors

    Science.gov (United States)

    Gnanvo, Kondo

    2017-09-01

    Gaseous detectors have played a pivotal role as tracking devices in the field of particle physics experiments for the last fifty years. Recent advances in photolithography and micro processing techniques have enabled the transition from Multi Wire Proportional Chambers (MWPCs) and Drift Chambers to a new family of gaseous detectors refer to as Micro Pattern Gaseous Detectors (MPGDs). MPGDs combine the basic gas amplification principle with micro-structure printed circuits to provide detectors with excellent spatial and time resolution, high rate capability, low material budget and high radiation tolerance. Gas Electron Multiplier (GEMs) is a well-established MPGD technology invented by F. Sauli at CERN in 1997 and deployed various high energy physics (HEP) and nuclear NP experiment for tracking systems of current and future NP experiments. GEM detector combines an exceptional high rate capability (1 MHz / mm2) and robustness against harsh radiation environment with excellent position and timing resolution performances. Recent breakthroughs over the past decade have allowed the possibility for large area GEMs, making them cost effective and high-performance detector candidates to play pivotal role in current and future particle physics experiments. After a brief introduction of the basic principle of GEM technology, I will give a brief overview of the GEM detectors used in particle physics experiments over the past decades and especially in the NP community at Thomas Jefferson National Laboratory (JLab) and Brookhaven National Laboratory (BNL). I will follow by a review of state of the art of the new GEM development for the next generation of colliders such as Electron Ion Collider (EIC) or High Luminosity LHC and future Nuclear Physics experiments. I will conclude with a presentation of the CERN-based RD51 collaboration established in 2008 and its major achievements regarding technological developments and applications of MPGDs.

  2. The gas electron multiplier (GEM)

    CERN Document Server

    Bouclier, Roger; Dominik, Wojciech; Hoch, M; Labbé, J C; Million, Gilbert; Ropelewski, Leszek; Sauli, Fabio; Sharma, A

    1996-01-01

    We describe operating priciples and results obtained with a new detector component: the Gas Electrons Multiplier (GEM). Consisting of a thin composite sheet with two metal layers separated by a thin insulator, and pierced by a regular matrix of open channels, the GEM electrode, inserted on the path of electrons in a gas detector, allows to transfer the charge with an amplification factor approaching ten. Uniform response and high rate capability are demonstrated. Coupled to another device, multiwire or micro-strip chamber, the GEM electrode permit to obtain higher gains or less critical operation; separation of the sensitive (conversion) volume and the detection volume has other advantages, as a built-in delay (useful for triggering purposes) and the possibility of applying high fields on the photo-cathode of ring imaging detectors to improve efficiency. Multiple GEM grids in the same gas volume allow to obtain large amplification factors in a succession of steps, leading to the realization of an effective ga...

  3. GEM the gas electron multiplier

    CERN Document Server

    Sauli, Fabio

    1997-01-01

    We describe the basic structure and operation of a new device, the Gas Electron Multiplier. Consisting in a polymer foil, metal-clad on both sides and perforated by a high density of holes, the GEM mesh allows to pre-amplify charges released in the gas with good uniformity and energy. Coupled to a micro-strip plate, the pre-amplification element allows to preserve high rate capability and resolution at considerably lower operating voltages, thus completely eliminating discharges and instabilities. Several GEM grids can be operated in cascade; charge gains are large enough to allow detection of signals in the ionization mode on the last element, permitting the use of a simple printed circuit as read-out electrode. Two-dimensional read-out can then be easily implemented. A new generation of simple, reliable and cheap fast position sensitive detectors seems at hand.

  4. Performance of gas electron multiplier (GEM) detector

    International Nuclear Information System (INIS)

    Han, S. H.; Moon, B. S.; Kim, Y. K.; Chung, C. E.; Kang, H. D.; Cho, H. S.

    2002-01-01

    We have investigated in detail the operating properties of Gas Electron Multiplier (GEM) detectors with a double conical and a cylindrical structure in a wide range of external fields and GEM voltages. With the double conical GEM, the gain gradually increased with time by 10%; whereas this surface charging was eliminated with the cylindrical GEM. Effective gains above 1000 were easily observed over a wide range of collection field strengths in a gas mixture of Ar/CO 2 (70/30). The transparency and electron collection efficiency were found to depend on the ratio of external field and the applied GEM voltage; the mutual influence of both drift and collection fields was found to be trivial

  5. Gas Electron Multipliers: Development of large area GEMs and spherical GEMs

    CERN Document Server

    Duarte Pinto, Serge; Brock, Ian

    2011-01-01

    Gaseous radiation detectors have been a crucial part of high-energy physics instrumentation since the 1960s, when the first multiwire proportional counters were built. In the 1990s the first micropattern gas detectors (MPGDs) saw the light; with sub-millimeter feature sizes these novel detectors were faster and more accurate than their predecessors. The gas electron multiplier (GEM) is one of the most successful of these technologies. It is a charge multiplication structure made from a copper clad polymer foil, pierced with a regular and dense pattern of holes. I will describe the properties and the application of GEMs and GEM detectors, and the research and development I have done on this technology. Two of the main objectives were the development of large area GEMs (~m^2) for particle physics experiments and GEMs with a spherical shape for x-ray or neutron diffraction detectors. Both have been realized, and the new techniques involved are finding their way to applications in research and industry.

  6. Gas electron multipliers. Development of large area GEMS and spherical GEMS

    Energy Technology Data Exchange (ETDEWEB)

    Pinto, Serge Duarte

    2011-08-15

    Gaseous radiation detectors have been a crucial part of high-energy physics instrumentation since the 1960s, when the first multiwire proportional counters were built. In the 1990s the first micropattern gas detectors (MPGDS) saw the light; with sub-millimeter feature sizes these novel detectors were faster and more accurate than their predecessors. The gas electron multiplier (GEM) is one of the most successful of these technologies. It is a charge multiplication structure made from a copper clad polymer foil, pierced with a regular and dense pattern of holes. I describe the properties and the application of GEMs and GEM. detectors, and the research and development I have done on this technology. Two of the main objectives were the development of large area GEMs ({proportional_to}m{sup 2}) for particle physics experiments and GEMs with a spherical shape for X-ray or neutron diffraction detectors. Both have been realized, and the new techniques involved are finding their way to applications in research and industry. (orig.)

  7. Gas electron multipliers: Development of large area GEMS and spherical GEMS

    International Nuclear Information System (INIS)

    Pinto, Serge Duarte

    2011-08-01

    Gaseous radiation detectors have been a crucial part of high-energy physics instrumentation since the 1960s, when the first multiwire proportional counters were built. In the 1990s the first micropattern gas detectors (MPGDS) saw the light; with sub-millimeter feature sizes these novel detectors were faster and more accurate than their predecessors. The gas electron multiplier (GEM) is one of the most successful of these technologies. It is a charge multiplication structure made from a copper clad polymer foil, pierced with a regular and dense pattern of holes. I describe the properties and the application of GEMs and GEM. detectors, and the research and development I have done on this technology. Two of the main objectives were the development of large area GEMs (∝m 2 ) for particle physics experiments and GEMs with a spherical shape for X-ray or neutron diffraction detectors. Both have been realized, and the new techniques involved are finding their way to applications in research and industry. (orig.)

  8. Gas electron multiplier (GEM) foil test, repair and effective gain calculation

    Science.gov (United States)

    Tahir, Muhammad; Zubair, Muhammad; Khan, Tufail A.; Khan, Ashfaq; Malook, Asad

    2018-06-01

    The focus of my research is based on the gas electron multiplier (GEM) foil test, repairing and effective gain calculation of GEM detector. During my research work define procedure of GEM foil testing short-circuit, detection short-circuits in the foil. Study different ways to remove the short circuits in the foils. Set and define the GEM foil testing procedures in the open air, and with nitrogen gas. Measure the leakage current of the foil and applying different voltages with specified step size. Define the Quality Control (QC) tests and different components of GEM detectors before assembly. Calculate the effective gain of GEM detectors using 109Cd and 55Fe radioactive source.

  9. Development of a time projection chamber using gas electron multipliers (GEM-TPC)

    International Nuclear Information System (INIS)

    Oda, S.X.; Hamagaki, H.; Ozawa, K.; Inuzuka, M.; Sakaguchi, T.; Isobe, T.; Gunji, T.; Morino, Y.; Saito, S.; Yamaguchi, Y.L.; Sawada, S.; Yokkaichi, S.

    2006-01-01

    We developed a prototype time projection chamber using gas electron multipliers (GEM-TPC) for high energy heavy ion collision experiments. To investigate its performance, we conducted a beam test with three kinds of gases (Ar(90%)-CH 4 (10%), Ar(70%)-C 2 H 6 (30%) and CF 4 ). Detection efficiency of 99%, and spatial resolution of 79μm in the pad-row direction and 313μm in the drift direction were achieved. The test results show that the GEM-TPC meets the requirements for high energy heavy ion collision experiments. The configuration and performance of the GEM-TPC are described

  10. Gas electron multiplier (GEM) operation with tissue-equivalent gases at various pressures

    International Nuclear Information System (INIS)

    Farahmand, M.; Bos, A.J.J.; Eijk, C.W.E. van

    2003-01-01

    We have studied the operation of two different Gas Electron Multiplier (GEM) structures in both methane and propane based Tissue-Equivalent (TE) gases at different pressures varying from 0.1 to 1 atm. This work was motivated to explore the possibility of using a GEM for a new type of Tissue Equivalent Proportional Counter. In methane based TE gas, a maximum safe GEM gain of 1.5x10 3 has been reached while in propane based TE gas this is 6x10 3 . These maxima have been reached at different gas pressures depending on GEM structure and TE gas. Furthermore, we observed a decrease of the GEM gain in time before it becomes stable. Charge up/polarisation effects can explain this

  11. The current status of the Gas Electron Multiplier (GEM) research at Kasetsart University, Thailand

    Science.gov (United States)

    Kumpiranon, P.; Kulasri, K.; Rittirong, A.; Saenboonruang, K.

    2017-06-01

    During the past decade, Gas Electron Multiplier (GEM) detectors have been greatly developed and utilized in numbers of applications including advanced nuclear and particle researches, medical imaging, astrophysics, and neutron detection for national security. Our GEM research group at the Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Thailand, realized in its excellent properties/potentials and started extensive researches on GEM detectors. To build a strong foundation on our research group, two 10 cm × 10 cm triple GEM detectors were characterized on their important properties including absolute gains and detection uniformity. Moreover, to widen applications of the GEM detector, our group had modified the GEM detector by introducing either solid or gaseous neutron converters to the detector so that the detector could effectively detect neutrons. These modifications included coating a thin film of 10B and natB to the GEM drift cathode for thermal neutron detection and flowing a gas mixture of He/CO2 (80:20 and 70:30) and C4H10/He/CO2 (7:70:23) for fast neutron detection. Results showed that the modified GEM-based neutron detector could detect both types of neutrons with different relative efficiencies and gains depending on thicknesses and types of neutron converters. This article discusses basic knowledge of the GEM detector, construction and testing procedures, results, and discussion.

  12. Secondary scintillation yield from GEM and THGEM gaseous electron multipliers for direct dark matter search

    Science.gov (United States)

    Monteiro, C. M. B.; Fernandes, L. M. P.; Veloso, J. F. C. A.; Oliveira, C. A. B.; dos Santos, J. M. F.

    2012-07-01

    The search for alternatives to PMTs as photosensors in optical TPCs for rare event detection has significantly increased in the last few years. In particular, in view of the next generation large volume detectors, the use of photosensors with lower natural radioactivity, such as large area APDs or GM-APDs, with the additional possibility of sparse surface coverage, triggered the intense study of secondary scintillation production in micropattern electron multipliers, such as GEMs and THGEMs, as alternatives to the commonly used uniform electric field region between two parallel meshes. The much higher scintillation output obtained from the electron avalanches in such microstructures presents an advantage in those situations. The accurate knowledge of the amount of such scintillation is important for correct detector simulation and optimization. It will also serve as a benchmark for software tools developed and/or under development for the calculation of the amount of such scintillation.The secondary scintillation yield, or electroluminescence yield, in the electron avalanches of GEMs and THGEMs operating in gaseous xenon and argon has been determined for different gas pressures. At 1 bar, THGEMs deliver electroluminescence yields that are more than one order of magnitude higher when compared to those achieved in GEMs and two orders of magnitude when compared to those achieved in a uniform field gap. The THGEM electroluminescence yield presents a faster decrease with pressure when comparing to the GEM electroluminescence yield, reaching similar values to what is achieved in GEMs for xenon pressures of 2.5 bar, but still one order of magnitude higher than that produced in a uniform field gap. Another exception is the GEM operating in argon, which presents an electroluminescence yield similar to that produced in a uniform electric field gap, while the THGEM achieves yields that are more than one order of magnitude higher.

  13. Development of Gas Electron Multiplier(GEM) for digital radiographic system

    International Nuclear Information System (INIS)

    Moon, B. S.; Chung, C. E.; Lee, J. W.

    2000-04-01

    Two computer programs SHOWFIELD and IMAGEQUAL have been developed. SHOWFIELD is used to draw electric field lines for GEM detectors and IMAGEQUAL is used to study the spatial resolution of x-ray images. Various simulation runs have been carried out using EGS4 to study the characteristics of electrons generated by micro-channel plates and Ar, Xe gases. A prototype GEM detector was developed through this project. The GEM detector is composed of a pair of GEM plates, a micro-channel plate, readout circuit in a gas filled chamber. GEM plate were made in CERN to meet KAERI's design specification and the micro-channel plates were purchased from Proxitronic company

  14. A how-to approach for a 3D simulation of charge transfer characteristics in a gas electron multiplier (GEM)

    CERN Document Server

    Sharma, A

    1999-01-01

    In this paper a detailed description of how to simulate charge transfer processes in a gaseous device is presented, taking the gas electron multiplier (GEM) as an example. A 3-dimensional simulation of the electric field and avalanche is performed. Results on charge transport are compared to experiment and agree within experimental errors; the avalanche mechanism and positive ion feedback are studied. The procedures used in the simulation are described in detail, and program scripts are appended. (15 refs).

  15. Test beam studies of Gas Electron Multiplier (GEM) detectors for the upgrade of CMS endcap muon system

    CERN Document Server

    Sharma, Ram Krishna

    2017-01-01

    The High Luminosity LHC (HL-LHC) will provide exceptional high instantaneous and integrated luminosity. The forward region $\\mid \\eta \\mid \\geq 1.5$ of the CMS detector will face extremely high particle rates in tens of $KHz/cm^{2}$ and hence it will affect the momentum resolution and longevity of the muon detectors. To overcome these issues the CMS collaboration has decided to install new large size rate capable Triple Gas Electron Multiplier (GEM) detectors in the forward region of CMS muon system. The first set of Triple GEM detectors will be installed in the GE1/1 region $(1.5 \\leq \\eta \\leq 2.2)$ of muon endcap during the LS2 of the LHC and the next one will be installed in the GE2/1 region $(1.6 \\leq \\eta \\leq 2.5)$, during the LS3. Towards this goal, full-size CMS Triple GEM prototype chambers have been fabricated and put under the test beam at the CERN SPS test beam facility. The GEM detectors were operated with two gas mixtures $Ar/CO_{2}$ (70/30) and $Ar/CO_{2}/CF_{4}$ (40/15/45). In 2014 and 2016, ...

  16. Muon Chamber Endcap Upgrade of the CMS Experiment with Gas Electron Multiplier (GEM) Detectors and their Performance

    CERN Document Server

    Gola, Mohit

    2017-01-01

    As the CERN LHC is heading towards a high luminosity phase a very high flux is expected in the endcaps of the CMS Detector. The presence of muons in collision events can be due to rare or new physics so it is important to maintain the high trigger efficiency of the CMS muon system. The CMS Collaboration has proposed to instrument the high-eta region (1.6 lt IetaI lt 2.2) of the muon endcaps with Gas Electron Multiplier (GEM) detectors, referred to as GE1/1 chambers, during the LS2. This technology will help in maintaining optimum trigger performance with maximum selection efficiency of muons even in a high flux environment. We describe plans for a Slice Test to installa few GE1/1 chambers covering 50 degrees in azimuthal angle within the CMS detector in 2017, with subsequent operation during the current Run 2 of the LHC. We show the performance of the GE1/1 chambers to be installed during the slice test, specifically GEM foil leakage currents, chamber gas volume integrity, high voltage circuit performanc...

  17. Preliminary results of the Gas Electron Multiplier (GEM) as real-time beam monitor in hadron therapy

    Energy Technology Data Exchange (ETDEWEB)

    Aza, E., E-mail: eleni.aza@cern.ch [CERN, Geneva 23, 1211 Geneva (Switzerland); AUTH, Department of Physics, 54124 Thessaloniki (Greece); Ciocca, M. [Fondazione CNAO, Strada Campeggi 53, 27100 Pavia (Italy); Murtas, F. [CERN, Geneva 23, 1211 Geneva (Switzerland); LNF-INFN, Via Fermi 40, 00044 Frascati (Italy); Puddu, S. [CERN, Geneva 23, 1211 Geneva (Switzerland); AEC-LHEP, University of Bern, Sidlerstrasse 5, 3012 Bern (Switzerland); Pullia, M. [Fondazione CNAO, Strada Campeggi 53, 27100 Pavia (Italy); Silari, M. [CERN, Geneva 23, 1211 Geneva (Switzerland)

    2017-01-01

    The use of proton and carbon ion beams in cancer therapy (also known as hadron therapy) is progressively growing worldwide due to their improved dose distributions, sparing of healthy tissues and (for carbon ions) increased radiobiological effectiveness especially for radio-resistant tumours. Strict Quality Assurance (QA) protocols need to be followed for guaranteeing the clinical beam specifications. The aim of this study was to assess the performance of a gaseous detector based on the Gas Electron Multiplier (GEM) technology for measuring the beam spot dimensions and the homogeneity of the scanned irradiation field, which are daily QA tasks commonly performed using radiochromic films. Measurements performed at the National Centre for Oncological Hadron Therapy (CNAO) in Pavia (Italy) showed that the detector is able to monitor the 2D beam image on-line with a pad granularity of 2 mm and a response proportional to the number of delivered particles. The dose homogeneity was measured with low deviation from the results obtained with radiochromic films.

  18. Operation of gas electron multiplier (GEM) with propane gas at low pressure and comparison with tissue-equivalent gas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    De Nardo, L., E-mail: laura.denardo@unipd.it [University of Padova, Physics and Astronomy Department and PD-INFN, via Marzolo 8, I-35131 Padova (Italy); Farahmand, M., E-mail: majid.farahmand@rivm.nl [Centre for Environmental Safety and Security, National Institute for Public Health and the Environment (RIVM), PO Box 1, NL-3720 BA Bilthoven (Netherlands)

    2016-05-21

    A Tissue-Equivalent Proportional Counter (TEPC), based on a single GEM foil of standard geometry, has been tested with pure propane gas at low pressure, in order to simulate a tissue site of about 1 µm equivalent size. In this work, the performance of GEM with propane gas at a pressure of 21 and 28 kPa will be presented. The effective gas gain was measured in various conditions using a {sup 244}Cm alpha source. The dependence of effective gain on the electric field strength along the GEM channel and in the drift and induction region was investigated. A maximum effective gain of about 5×10{sup 3} has been reached. Results obtained in pure propane gas are compared with gas gain measurements in gas mixtures commonly employed in microdosimetry, that is propane and methane based Tissue-Equivalent gas mixtures.

  19. Experiment study on the thick GEM-like multiplier for X-ray photoelectrons energy deposition gaining

    International Nuclear Information System (INIS)

    Zhu Pengfei; Ye Yan; Long Yan; Cao Ningxiang; Jia Xing; Li Jianfeng

    2009-01-01

    The GEM is a novel detector with high gain,high time and location resolution. Imitating the structure of the GEM, a thick GEM-like multiplier which has the similar function with that of the GEM is designed and manufactured. The characteristics of the thick GEM-like multiplier increasing electron energy deposition in absorbing medium has been experimentally studied. The results indicate that the energy deposition gain of x-ray photoelectron in medium is apparent, and the maximum energy deposition can increase by more than 40%. Some suggestions of further increasing the energy deposition are given, and the future application of the way of increasing the x-ray photoelectron energy deposition by the thick GEM-like multiplier in hard x-ray imaging is prospected. (authors)

  20. Fabrication and measurement of gas electron multiplier

    International Nuclear Information System (INIS)

    Zhang Minglong; Xia Yiben; Wang Linjun; Gu Beibei; Wang Lin; Yang Ying

    2005-01-01

    Gas electron multiplier (GEM) with special performance has been widely used in the field of radiation detectors. In this work, GEM film was fabricated using a 50 μm -thick kapton film by the therma evaporation and laser masking drilling technique. GEM film has many uniformly arrayed holes with a diameter of 100 μm and a gap of 223 μm. It was then set up to a gas-flowing detector with an effective area of 3 x 3 cm 2 , 5.9 keV X-ray generated from a 55 Fe source was used to measure the pulse height distribution of GEM operating at various high voltage and gas proportion. The effect of high potential and gas proportion on the count rate and the energy resolution was discussed in detail. The results indicate that GEM has a very high ratio of signal to noise and better energy resolution of 18.2%. (authors)

  1. Ceramic Electron Multiplier

    International Nuclear Information System (INIS)

    Comby, G.

    1996-01-01

    The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

  2. Channel electron multipliers

    International Nuclear Information System (INIS)

    Seidman, A.; Avrahami, Z.; Sheinfux, B.; Grinberg, J.

    1976-01-01

    A channel electron multiplier is described having a tubular wall coated with a secondary-electron emitting material and including an electric field for accelerating the electrons, the electric field comprising a plurality of low-resistive conductive rings each alternating with a high-resistive insulating ring. The thickness of the low-resistive rings is many times larger than that of the high-resistive rings, being in the order of tens of microns for the low-resistive rings and at least one order of magnitude lower for the high-resistive rings; and the diameter of the channel tubular walls is also many times larger than the thickness of the high-resistive rings. Both single-channel and multiple-channel electron multipliers are described. A very important advantage, particularly in making multiple-channel multipliers, is the simplicity of the procedure that may be used in constructing such multipliers. Other operational advantages are described

  3. Microchannel electron multiplier

    International Nuclear Information System (INIS)

    Beranek, I.; Janousek, L.; Vitovsky, O.

    1981-01-01

    A microchannel electron multiplier is described for detecting low levels of alpha, beta, soft X-ray and UV radiations. It consists of a glass tube or a system of tubes of various shapes made of common technological glass. The inner tube surface is provided with an active coat with photoemitter and secondary emitter properties. (B.S.)

  4. Charge-transfer properties in the gas electron multiplier

    International Nuclear Information System (INIS)

    Han, Sanghyo; Kim, Yongkyun; Cho, Hyosung

    2004-01-01

    The charge transfer properties of a gas electron multiplier (GEM) were systematically investigated over a broad range of electric field configurations. The electron collection efficiency and the charge sharing were found to depend on the external fields, as well as on the GEM voltage. The electron collection efficiency increased with the collection field up to 90%, but was essentially independent of the drift field strength. A double conical GEM has a 10% gain increase with time due to surface charging by avalanche ions whereas this effect was eliminated with the cylindrical GEM. The positive-ion feedback is also estimated. (author)

  5. Charge transfer in gas electron multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ottnad, Jonathan; Ball, Markus; Ketzer, Bernhard; Ratza, Viktor; Razzaghi, Cina [HISKP, Bonn University, Nussallee 14-16, D-53115 Bonn (Germany)

    2015-07-01

    In order to efficiently employ a Time Projection Chamber (TPC) at interaction rates higher than ∝1 kHz, as foreseen e.g. in the ALICE experiment (CERN) and at CB-ELSA (Bonn), a continuous operation and readout mode is required. A necessary prerequisite is to minimize the space charge coming from the amplification system and to maintain an excellent spatial and energy resolution. Unfortunately these two goals can be in conflict to each other. Gas Electron Multipliers (GEM) are one candidate to fulfill these requirements. It is necessary to understand the processes within the amplification structure to find optimal operation conditions. To do so, we measure the charge transfer processes in and between GEM foils with different geometries and field configurations, and use an analytical model to describe the results. This model can then be used to predict and optimize the performance. The talk gives the present status of the measurements and describes the model.

  6. The Gas Electron Multiplier Chamber Exhibition LEPFest 2000

    CERN Multimedia

    2000-01-01

    The Gas Electron Multiplier (GEM) is a novel device introduced in 1996.Large area detectors based on this technology are in construction for high energy physics detectors.This technology can also be used for high-rate X-ray imaging in medical diagnostics and for monitoring irradiation during cancer treatment

  7. Charge amplification and transfer processes in the gas electron multiplier

    International Nuclear Information System (INIS)

    Bachmann, S.; Bressan, A.; Ropelewski, L.; Sauli, F.; Sharma, A.; Moermann, D.

    1999-01-01

    We report the results of systematic investigations on the operating properties of detectors based on the gas electron multiplier (GEM). The dependence of gain and charge collection efficiency on the external fields has been studied in a range of values for the hole diameter and pitch. The collection efficiency of ionization electrons into the multiplier, after an initial increase, reaches a plateau extending to higher values of drift field the larger the GEM voltage and its optical transparency. The effective gain, fraction of electrons collected by an electrode following the multiplier, increases almost linearly with the collection field, until entering a steeper parallel plate multiplication regime. The maximum effective gain attainable increases with the reduction in the hole diameter, stabilizing to a constant value at a diameter approximately corresponding to the foil thickness. Charge transfer properties appear to depend only on ratios of fields outside and within the channels, with no interaction between the external fields. With proper design, GEM detectors can be optimized to satisfy a wide range of experimental requirements: tracking of minimum ionizing particles, good electron collection with small distortions in high magnetic fields, improved multi-track resolution and strong ion feedback suppression in large volume and time-projection chambers

  8. GEM: Performance and aging tests

    International Nuclear Information System (INIS)

    Cho, H.S.; Kadyk, J.; Han, S.H.; Hong, W.S.; Perez-Mendez, V.; Wenzel, W.; Pitts, K.; Martin, M.D.; Hutchins, J.B.

    1999-01-01

    Performance and aging tests have been done to characterize Gas Electron Multipliers (GEMs), including further design improvements such as a thicker GEM and a closed GEM. Since the effective GEM gain is typically smaller than the absolute GEM gain, due to trapping of avalanche electrons at the bottom GEM electrode, the authors performed field simulations and measurements for better understanding, and discuss methods to eliminate this effect. Other performance parameters of the GEMs are also presented, including absolute GEM gain, short-term and long-term gain stabilities

  9. High- and low-pressure operation of the gas electron multiplier

    International Nuclear Information System (INIS)

    Bondar, A.; Buzulutskov, A.; Shekhtman, L.; Sauli, F.

    1998-01-01

    We have studied the operation of the gas electron multiplier (GEM) in gas mixtures Xe-CO 2 , Ar-CO 2 and CH 4 at different pressures varying from 0.1 to 5 atm. In Ar- and Xe-based mixtures, the maximum GEM gain considerably decreases with pressure, from a few hundreds at 1 atm to below 10 at 5 atm. Combined gain of GEM and the micro-strip gas chamber (MSGC) can exceed values of 10000 at 1 atm and 100 at 5 atm. High GEM gains, of above 1000, were obtained in CH 4 at low pressures. We have observed the effect of the avalanche confinement in GEM micro-holes, resulting in violation of the pressure scaling and in the possibility of GEM operation in pure noble gases. (author)

  10. Spin sensitivity of a channel electron multiplier

    International Nuclear Information System (INIS)

    Scholten, R.E.; McClelland, J.J.; Kelley, M.H.; Celotta, R.J.

    1988-01-01

    We report direct measurements of the sensitivity of a channel electron multiplier to electrons with different spin orientations. Four regions of the multiplier cone were examined using polarized electrons at 100-eV incident energy. Pulse counting and analog modes of operation were both investigated and in each case the observed spin effects were less than 0.5%

  11. Numerical Investigation on Electron and Ion Transmission of GEM-based Detectors

    Science.gov (United States)

    Bhattacharya, Purba; Sahoo, Sumanya Sekhar; Biswas, Saikat; Mohanty, Bedangadas; Majumdar, Nayana; Mukhopadhyay, Supratik

    2018-02-01

    ALICE at the LHC is planning a major upgrade of its detector systems, including the TPC, to cope with an increase of the LHC luminosity after 2018. Different R&D activities are currently concentrated on the adoption of the Gas Electron Multiplier (GEM) as the gas amplification stage of the ALICE-TPC upgrade version. The major challenge is to have low ion feedback in the drift volume as well as to ensure a collection of good percentage of primary electrons in the signal generation process. In the present work, Garfield simulation framework has been adopted to numerically estimate the electron transparency and ion backflow fraction of GEM-based detectors. In this process, extensive simulations have been carried out to enrich our understanding of the complex physical processes occurring within single, triple and quadruple GEM detectors. A detailed study has been performed to observe the effect of detector geometry, field configuration and magnetic field on the above mentioned characteristics.

  12. 3D simulation of electron and ion transmission of GEM-based detectors

    Science.gov (United States)

    Bhattacharya, Purba; Mohanty, Bedangadas; Mukhopadhyay, Supratik; Majumdar, Nayana; da Luz, Hugo Natal

    2017-10-01

    Time Projection Chamber (TPC) has been chosen as the main tracking system in several high-flux and high repetition rate experiments. These include on-going experiments such as ALICE and future experiments such as PANDA at FAIR and ILC. Different R&D activities were carried out on the adoption of Gas Electron Multiplier (GEM) as the gas amplification stage of the ALICE-TPC upgrade version. The requirement of low ion feedback has been established through these activities. Low ion feedback minimizes distortions due to space charge and maintains the necessary values of detector gain and energy resolution. In the present work, Garfield simulation framework has been used to study the related physical processes occurring within single, triple and quadruple GEM detectors. Ion backflow and electron transmission of quadruple GEMs, made up of foils with different hole pitch under different electromagnetic field configurations (the projected solutions for the ALICE TPC) have been studied. Finally a new triple GEM detector configuration with low ion backflow fraction and good electron transmission properties has been proposed as a simpler GEM-based alternative suitable for TPCs for future collider experiments.

  13. Electron cyclotron resonance multiply charged ion sources

    International Nuclear Information System (INIS)

    Geller, R.

    1975-01-01

    Three ion sources, that deliver multiply charged ion beams are described. All of them are E.C.R. ion sources and are characterized by the fact that the electrons are emitted by the plasma itself and are accelerated to the adequate energy through electron cyclotron resonance (E.C.R.). They can work without interruption during several months in a quasi-continuous regime. (Duty cycle: [fr

  14. Evaporator line for special electron tubes, in particular electron multipliers

    International Nuclear Information System (INIS)

    Richter, M.

    1984-01-01

    The invention has been aimed at reducing the effort for preventing short circuits in achieving certain material-dependent effects e.g. secondary emission, by deposition through evaporation in the production of electron tubes, in particular electron multipliers

  15. Development of a glass GEM

    International Nuclear Information System (INIS)

    Takahashi, Hiroyuki; Mitsuya, Yuki; Fujiwara, Takeshi; Fushie, Takashi

    2013-01-01

    Gas electron multipliers (GEMs) apply the concept of gas amplification inside many tiny holes, realizing robust and high-gain proportional counters. However, the polyimide substrate of GEMs prevents them from being used in sealed detector applications. We have fabricated and tested glass GEMs (G-GEMs) with substrates made of photosensitive glass material from the Hoya Corporation. We fabricated G-GEMs with several different hole diameters and thicknesses and successfully operated test G-GEMs with a 100×100 mm 2 effective area. The uniformity of our G-GEMs was good, and the energy resolution for 5.9 keV X-rays was 18.8% under uniform irradiation of the entire effective area. A gas gain by the G-GEMs of up to 6700 was confirmed with a gas mixture of Ar (70%)+CH 4 (30%). X-ray imaging using the charge division readout method was demonstrated

  16. Electronic de-multipliers; Demultiplicateurs electroniques

    Energy Technology Data Exchange (ETDEWEB)

    Ailloud, J

    1948-07-01

    The counting of a huge number of events, randomly or periodically distributed, requires the use of electronic counters which can work with a flow of up to 500000 events per second, while mechanical systems have a much lower resolution which leads to an important percentage of losses (non-counted events). Thus, hybrid systems are generally used which comprise an electronic part with fast counting capabilities but low recording capacities, and a mechanical part for the recording of the successive resets of the electronic part. This report describes the basic elementary circuits of these electronic counters (de-multipliers): dividers by 2 and 5 and flip-flop circuits using triode and pentode valves for the counting of events in the decimal system. (J.S.)

  17. Effects of tritium on electron multiplier performance

    International Nuclear Information System (INIS)

    Kerst, R.A.; Malinowski, M.E.

    1980-01-01

    In developing diagnostic instruments for fusion reactors, it is necessary to measure the effects of tritium contamination on channel electron multipliers (CEM). A CEM was exposed to T 2 pressures of up to 1.5 x 10 -1 Pa, with exposure quantities ranging up to 8800 Pa-s. The counting rate of the CEM is shown to consist of a prompt (Type I) signal caused by gas-phase tritium and a residual (Type II) signal, probably caused by near-surface tritium. The potential for using CEMs for observing the dynamics of tritium adsorption and absorption is discussed

  18. Single electron based binary multipliers with overflow detection ...

    African Journals Online (AJOL)

    electron based device. Multipliers with overflow detection based on serial and parallel prefix computation algorithm are elaborately discussed analytically and designed. The overflow detection circuits works in parallel with a simplified multiplier to ...

  19. 3D Observation of GEMS by Electron Tomography

    Science.gov (United States)

    Matsuno, Junya; Miyake, Akira; Tsuchiyama, Akira; Nakamura-Messenger, Keiko; Messenger, Scott

    2014-01-01

    Amorphous silicates in chondritic porous interplanetary dust particles (CP-IDPs) coming from comets are dominated by glass with embedded metal and sulfides (GEMS). GEMS grains are submicron-sized rounded objects (typically 100-500) nm in diameter) with anaometer-sized (10-50 nm) Fe-Ni metal and sulfide grains embedded in an amorphous silicate matrix. Several formation processes for GEMS grains have been proposed so far, but these models are still being debated [2-5]. Bradley et al. proposed that GEMS grains are interstellar silicate dust that survived various metamorphism or alteration processes in the protoplanetary disk and that they are amorphiation products of crystalline silicates in the interstellar medium by sputter-deposition of cosmic ray irradiation, similar to space weathering [2,4]. This consideration is based on the observation of nano-sized crystals (approximately 10 nm) called relict grains in GEMS grains and their shapes are pseudomorphs to the host GEMS grains. On the other hand, Keller and Messenger proposed that most GEMS formed in the protoplanetary disk as condensates from high temperature gas [3,5]. This model is based on the fact that most GEMS grains have solar isotopic compositions and have extremely heterogeneous and non-solar elemental compositions. Keller and Messenger (2011) also reported that amorphous silicates in GEMS grains are surrounded by sulfide grains, which formed as sulfidization of metallic iron grains located on the GEMS surface. The previous studies were performed with 2D observation by using transmission electron microscopy (TEM) or scanning TEM (STEM). In order to understand the structure of GEMS grains described above more clearly, we observed 3D structure of GEMS grains by electron tomography using a TEM/STEM (JEM-2100F, JEOL) at Kyoto University. Electron tomography gives not only 3D structures but also gives higher spatial resolution (approximately a few nm) than that in conventional 2D image, which is restricted by

  20. Development of a Diehard GEM using PTFE insulator substrate

    OpenAIRE

    Wakabayashi, M.; Komiya, K.; Tamagawa, T.; Takeuchi, Y.; Aoki, K.; Taketani, A.; Hamagaki, H.

    2014-01-01

    We have developed the gas electron multiplier (GEM) using polytetrafluoroethylene (PTFE) insulator substrate (PTFE-GEM). Carbonization on insulator layer by discharges shorts the GEM electrodes, causing permanent breakdown. Since PTFE is hard to be carbonized against arc discharges, PTFE-GEM is expected to be robust against breakdown. Gains as high as 2.6x10^4 were achieved with PTFE-GEM (50 um thick) in Ar/CO2 = 70%/30% gas mixture at V_GEM = 730V. PTFE-GEM never showed a permanent breakdown...

  1. Numerical Investigation on Electron and Ion Transmission of GEM-based Detectors

    Directory of Open Access Journals (Sweden)

    Bhattacharya Purba

    2018-01-01

    Full Text Available ALICE at the LHC is planning a major upgrade of its detector systems, including the TPC, to cope with an increase of the LHC luminosity after 2018. Different R&D activities are currently concentrated on the adoption of the Gas Electron Multiplier (GEM as the gas amplification stage of the ALICE-TPC upgrade version. The major challenge is to have low ion feedback in the drift volume as well as to ensure a collection of good percentage of primary electrons in the signal generation process. In the present work, Garfield simulation framework has been adopted to numerically estimate the electron transparency and ion backflow fraction of GEM-based detectors. In this process, extensive simulations have been carried out to enrich our understanding of the complex physical processes occurring within single, triple and quadruple GEM detectors. A detailed study has been performed to observe the effect of detector geometry, field configuration and magnetic field on the above mentioned characteristics.

  2. Tritium-caused background currents in electron multipliers

    International Nuclear Information System (INIS)

    Malinowski, M.E.

    1979-05-01

    One channel electron multiplier (Galileo No. 4501) and one 14 stage Be/Cu multiplier (Dumont No. SPM3) were exposed to tritium pressures between approx. 10 -7 Torr to 10 -3 Torr in amounts from approx. 10 -5 Torr-s to 60 Torr-s and the β-decay caused currents in the multipliers measured. The background currents in both multipliers consisted of two components: (1) a high, reversible current which was proportional to the tritium exposure pressure; and (2) a lower, irreversible background current which increased with increasing cumulative tritium exposure. The β-decay caused currents in each multiplier increased the same way with exposure, suggesting the detected electrons arose from decaying tritium adsorbed on surfaced external to the multipliers

  3. Production processes of multiply charged ions by electron impact

    International Nuclear Information System (INIS)

    Oda, Nobuo

    1980-02-01

    First, are compared the foil or gas stripper and the ion sources utilizing electron-atom ionizing collisions, which are practically used or are under development to produce multiply charged ions. A review is made of the fundamental physical parameters such as successive ionization potentials and various ionization cross sections by electron impact, as well as the primary processes in multiply charged ion production. Multiply charged ion production processes are described for the different existing ion sources such as high temperature plasma type, ion-trapping type and discharge type. (author)

  4. Simulation and Digitization of a Gas Electron Multiplier Detector Using Geant4 and an Object-Oriented Digitization Program

    Science.gov (United States)

    McMullen, Timothy; Liyanage, Nilanga; Xiong, Weizhi; Zhao, Zhiwen

    2017-01-01

    Our research has focused on simulating the response of a Gas Electron Multiplier (GEM) detector using computational methods. GEM detectors provide a cost effective solution for radiation detection in high rate environments. A detailed simulation of GEM detector response to radiation is essential for the successful adaption of these detectors to different applications. Using Geant4 Monte Carlo (GEMC), a wrapper around Geant4 which has been successfully used to simulate the Solenoidal Large Intensity Device (SoLID) at Jefferson Lab, we are developing a simulation of a GEM chamber similar to the detectors currently used in our lab. We are also refining an object-oriented digitization program, which translates energy deposition information from GEMC into electronic readout which resembles the readout from our physical detectors. We have run the simulation with beta particles produced by the simulated decay of a 90Sr source, as well as with a simulated bremsstrahlung spectrum. Comparing the simulation data with real GEM data taken under similar conditions is used to refine the simulation parameters. Comparisons between results from the simulations and results from detector tests will be presented.

  5. Development of a Diehard GEM using PTFE insulator substrate

    International Nuclear Information System (INIS)

    Wakabayashi, M; Tamagawa, T; Takeuchi, Y; Aoki, K; Taketani, A; Komiya, K; Hamagaki, H

    2014-01-01

    We have developed the gas electron multiplier (GEM) using polytetrafluoroethylene (PTFE) insulator substrate (PTFE-GEM). Carbonization on insulator layer by discharges shorts the GEM electrodes, causing permanent breakdown. Since PTFE is hard to be carbonized against arc discharges, PTFE-GEM is expected to be robust against breakdown. Gains as high as 2.6 × 10 4 were achieved with PTFE-GEM (50 μm thick) in Ar/CO 2 = 70%/30% gas mixture at V GEM = 730 V. PTFE-GEM never showed a permanent breakdown even after suffering more than 40000 times discharges during the experiment. The result demonstrates that PTFE-GEM is really robust against discharges. We conclude that PTFE is an excellent insulator material for the GEM productions

  6. Electronic de-multipliers II (ring-shape systems)

    International Nuclear Information System (INIS)

    Raievski, V.

    1948-09-01

    This report describes a new type of ring-shape fast electronic counter (de-multiplier) with a resolution capacity equivalent to the one made by Regener (Rev. of Scientific Instruments USA 1946, 17, 180-89) but requiring two-times less electronic valves. This report follows the general description of electronic de-multipliers made by J. Ailloud (CEA--001). The ring comprises 5 flip-flop circuits with two valves each. The different elements of the ring are calculated with enough details to allow the transfer of this calculation to different valve types. (J.S.)

  7. GEM simulation methods development

    International Nuclear Information System (INIS)

    Tikhonov, V.; Veenhof, R.

    2002-01-01

    A review of methods used in the simulation of processes in gas electron multipliers (GEMs) and in the accurate calculation of detector characteristics is presented. Such detector characteristics as effective gas gain, transparency, charge collection and losses have been calculated and optimized for a number of GEM geometries and compared with experiment. A method and a new special program for calculations of detector macro-characteristics such as signal response in a real detector readout structure, and spatial and time resolution of detectors have been developed and used for detector optimization. A detailed development of signal induction on readout electrodes and electronics characteristics are included in the new program. A method for the simulation of charging-up effects in GEM detectors is described. All methods show good agreement with experiment

  8. The Tynode: A new vacuum electron multiplier

    Energy Technology Data Exchange (ETDEWEB)

    Graaf, Harry van der, E-mail: vdgraaf@nikhef.nl [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Akhtar, Hassan; Budko, Neil; Chan, Hong Wah; Hagen, Cornelis W. [Delft University of Technology, Delft (Netherlands); Hansson, Conny C.T. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Nützel, Gert; Pinto, Serge D. [Photonis, Roden (Netherlands); Prodanović, Violeta; Raftari, Behrouz; Sarro, Pasqualina M. [Delft University of Technology, Delft (Netherlands); Sinsheimer, John; Smedley, John [Brookhaven National Laboratory, Upton, NY 11973 (United States); Tao, Shuxia [Eindhoven University of Technology/DIFFER (Netherlands); Theulings, Anne M.M.G. [Delft University of Technology, Delft (Netherlands); Nikhef, Science Park 105, 1098 XG Amsterdam (Netherlands); Vuik, Kees [Delft University of Technology, Delft (Netherlands)

    2017-03-01

    By placing, in vacuum, a stack of transmission dynodes (tynodes) on top of a CMOS pixel chip, a single free electron detector could be made with outstanding performance in terms of spatial and time resolution. The essential object is the tynode: an ultra thin membrane, which emits, at the impact of an energetic electron on one side, a multiple of electrons at the other side. The electron yields of tynodes have been calculated by means of GEANT-4 Monte Carlo simulations, applying special low-energy extensions. The results are in line with another simulation based on a continuous charge-diffusion model. By means of Micro Electro Mechanical System (MEMS) technology, tynodes and test samples have been realized. The secondary electron yield of several samples has been measured in three different setups. Finally, several possibilities to improve the yield are presented.

  9. Multiply excited molecules produced by photon and electron interactions

    International Nuclear Information System (INIS)

    Odagiri, T.; Kouchi, N.

    2006-01-01

    The photon and electron interactions with molecules resulting in the formation of multiply excited molecules and the subsequent decay are subjects of great interest because the independent electron model and Born-Oppenheimer approximation are much less reliable for the multiply excited states of molecules than for the ground and lower excited electronic states. We have three methods to observe and investigate multiply excited molecules: 1) Measurements of the cross sections for the emission of fluorescence emitted by neutral fragments in the photoexcitation of molecules as a function of incident photon energy [1-3], 2) Measurements of the electron energy-loss spectra tagged with the fluorescence photons emitted by neutral fragments [4], 3) Measurements of the cross sections for generating a pair of photons in absorption of a single photon by a molecule as a function of incident photon energy [5-7]. Multiply excited states degenerate with ionization continua, which make a large contribution in the cross section curve involving ionization processes. The key point of our methods is hence that we measure cross sections free from ionization. The feature of multiply excited states is noticeable in such a cross section curve. Recently we have measured: i) the cross sections for the emission of the Lyman- fluorescence in the photoexcitation of CH 4 as a function of incident photon energy in the range 18-51 eV, ii) the electron energy-loss spectrum of CH 4 tagged with the Lyman-photons at 80 eV incident electron energy and 10 electron scattering angle in the range of the energy loss 20-45 eV, in order to understand the formation and decay of the doubly excited methane in photon and electron interactions. [8] The results are summarized in this paper and the simultaneous excitation of two electrons by electron interaction is compared with that by photon interaction in terms of the oscillator strength. (authors)

  10. Ion feedback effect in the multi GEM structure

    International Nuclear Information System (INIS)

    Park, Se Hwan; Kim, Yong Kyun; Han, Sang Hyo; Ha, Jang Ho; Moon, Byung Soo; Chung, Chong Eun

    2003-01-01

    The feedback of positive ions in a gas electron multiplier (GEM) has to be suppressed to reduce the photocathode degradation in GEM photomultipliers and to prevent the field distortion in a time projection chamber (TPC). The ion feedback dependency on the drift electric field, the transfer field, the asymmetry in the voltages across the GEM, and the effective gain was carefully measured in various gases. The ion feedback is sensitive to the drift field and the effective gain. A model prediction of the ion feedback in a double GEM structure was compared with the measurement. Our systematic study of the ion feedback effect can lead to progress in gas detectors with GEMs.

  11. Summer Student Project: GEM Simulation and Gas Mixture Characterization

    CERN Document Server

    Oviedo Perhavec, Juan Felipe

    2013-01-01

    Abstract This project is a numerical simulation approach to Gas Electron Multiplier (GEM) detectors design. GEMs are a type of gaseous ionization detector that have proposed as an upgrade for CMS muon endcap. The main advantages of this technology are high spatial and time resolution and outstanding aging resistance. In this context, fundamental physical behavior of a Gas Electron Multiplier (GEM) is analyzed using ANSYS and Garfield++ software coupling. Essential electron transport properties for several gas mixtures were computed as a function of varying electric and magnetic field using Garfield++ and Magboltz.

  12. Progress on large area GEMs (VCI 2010)

    CERN Document Server

    Villa, Marco; Alfonsi, Matteo; Brock, Ian; Croci, Gabriele; David, Eric; de Oliveira, Rui; Ropelewski, Leszek; Taureg, Hans; van Stenis, Miranda

    2011-01-01

    The Gas Electron Multiplier (GEM) manufacturing technique has recently evolved to allow the production of large area GEMs. A novel approach based on single mask photolithography eliminates the mask alignment issue, which limits the dimensions in the traditional double mask process. Moreover, a splicing technique overcomes the limited width of the raw material. Stretching and handling issues in large area GEMs have also been addressed. Using the new improvements it was possible to build a prototype triple-GEM detector of ~ 2000 cm2 active area, aimed at an application for the TOTEM T1 upgrade. Further refinements of the single mask technique give great control over the shape of the GEM holes and the size of the rims, which can be tuned as needed. In this framework, simulation studies can help to understand the GEM behavior depending on the hole shape.

  13. Gaseous electron multiplier-based soft x-ray plasma diagnostics development: Preliminary tests at ASDEX Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Chernyshova, M., E-mail: maryna.chernyshova@ipplm.pl; Malinowski, K.; Czarski, T.; Kowalska-Strzęciwilk, E. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Wojeński, A.; Poźniak, K. T.; Kasprowicz, G.; Krawczyk, R.; Kolasiński, P.; Zabołotny, W.; Zienkiewicz, P. [Institute of Electronic Systems, Warsaw University of Technology, Nowowiejska 15/19, 00-665 Warsaw (Poland); Vezinet, D.; Herrmann, A. [Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching (Germany); Mazon, D.; Jardin, A. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)

    2016-11-15

    A Gaseous Electron Multiplier (GEM)-based detector is being developed for soft X-ray diagnostics on tokamaks. Its main goal is to facilitate transport studies of impurities like tungsten. Such studies are very relevant to ITER, where the excessive accumulation of impurities in the plasma core should be avoided. This contribution provides details of the preliminary tests at ASDEX Upgrade (AUG) with a focus on the most important aspects for detector operation in harsh radiation environment. It was shown that both spatially and spectrally resolved data could be collected, in a reasonable agreement with other AUG diagnostics. Contributions to the GEM signal include also hard X-rays, gammas, and neutrons. First simulations of the effect of high-energy photons have helped understanding these contributions.

  14. A GEM-TPC prototype with low-Noise highly integrated front-end electronics for linear collider studies

    CERN Document Server

    Kappler, Steffen; Kaminski, Jochen; Ledermann, Bernhard; Müller, Thomas; Ronan, Michael T; Ropelewski, Leszek; Sauli, Fabio; Settles, Ronald

    2004-01-01

    Connected to the linear collider project, studies on the readout of time projection chambers (TPCs) based on the gas electron multiplier (GEM) are ongoing. Higher granularity and intrinsically suppressed ion feedback are the major advantages of this technology. After a short discussion of these issues, we present the design of a small and very flexible TPC prototype, whose cylindrical drift volume can be equipped with endcaps of different gas detector types. An endcap with multi-GEM readout is currently set up and successfully operated with a low-noise highly integrated front-end electronics. We discuss results of measurements with this system in high intensity particle beams at CERN, where 99.3 plus or minus 0.2% single-pad-row efficiency could be achieved at an effective gain of 2.5 multiplied by 10**3 only, and spatial resolutions down to 63 plus or minus 3 mum could be demonstrated. Finally, these results are extrapolated to the high magnetic field in a linear collider TPC. 5 Refs.

  15. Statistics of electron multiplication in multiplier phototube: iterative method

    International Nuclear Information System (INIS)

    Grau Malonda, A.; Ortiz Sanchez, J.F.

    1985-01-01

    An iterative method is applied to study the variation of dynode response in the multiplier phototube. Three different situations are considered that correspond to the following ways of electronic incidence on the first dynode: incidence of exactly one electron, incidence of exactly r electrons and incidence of an average anti-r electrons. The responses are given for a number of steps between 1 and 5, and for values of the multiplication factor of 2.1, 2.5, 3 and 5. We study also the variance, the skewness and the excess of jurtosis for different multiplication factors. (author)

  16. Statistics of electron multiplication in a multiplier phototube; Iterative method

    International Nuclear Information System (INIS)

    Ortiz, J. F.; Grau, A.

    1985-01-01

    In the present paper an iterative method is applied to study the variation of dynode response in the multiplier phototube. Three different situation are considered that correspond to the following ways of electronic incidence on the first dynode: incidence of exactly one electron, incidence of exactly r electrons and incidence of an average r electrons. The responses are given for a number of steps between 1 and 5, and for values of the multiplication factor of 2.1, 2.5, 3 and 5. We study also the variance, the skewness and the excess of jurtosis for different multiplication factors. (Author) 11 refs

  17. Progress in GEM-based gaseous photomultipliers

    CERN Document Server

    Chechik, R; Breskin, Amos; Buzulutskov, A F; Guedes, G P; Mörmann, D; Singh, B K

    2003-01-01

    We discuss recent progress in gaseous photomultipliers (GPMTs) comprising UV-to-visible spectral range photocathodes (PCs) coupled to multiple Gas Electron Multipliers (GEM). The PCs may be either semitransparent or reflective ones directly deposited on the first-GEM surface. These detectors provide high gain, even in noble gases, are sensitive to single photons, have nanosecond time resolution, and offer good localization. The operation of CsI-based GPMTs in CF sub 4 opens new applications in Cherenkov detectors, where both the radiator and the photosensor operate in the same gas. The latest results on sealed visible-light detectors, combining bialkali PCs and Kapton-made GEMs are presented.

  18. Study of etching processes in the GEM detectors

    CERN Document Server

    Zavazieva, Darina

    2016-01-01

    Gaseous Electron Multiplier (GEM) detectors are known to operate stably at high gains and high particle fluxes. Though, at very high gains and fluxes it was observed that the insulating polyimide layer between the GEM electrodes gets etched, changing the original shape of the hole, and therefore varying the gain and the energy resolution of the detector. The idea of the project to observe degradation effect of the GEM foils during the Triple GEM detector operation in extreme conditions under X-ray radiation.

  19. Development of a thick gas electron multiplier for microdosimetry

    International Nuclear Information System (INIS)

    Orchard, G.M.; Chin, K.; Prestwich, W.V.; Waker, A.J.; Byun, S.H.

    2011-01-01

    A new tissue-equivalent proportional counter based on a thick gas electron multiplier (THGEM) was developed and tested for microdosimetry. A systematic test was conducted at the McMaster Accelerator Laboratory to investigate the overall performance of the prototype detector. A mixed neutron-gamma-ray radiation field was generated using the 7 Li(p,n) reaction. The detector was operated at low voltage initially to test the stability and then the relative multiplication gain was measured as a function of the operating high voltage. A drift potential of 100 V and a THGEM bias of 727 V generated a multiplication gain sufficient for the detection of both neutron and gamma-ray radiation. A consistent microdosimetric pattern was observed between the THGEM detector and standard TEPC for microdosimetry.

  20. Research on nonlinearity effect of secondary electron multiplier

    International Nuclear Information System (INIS)

    Wei Xingjian; Liao Junsheng; Deng Dachao; Yu Chunrong; Yuan Li

    2007-01-01

    The nonlinearity of secondary electron multiplier (SEM) of a thermal ionization mass spectrometer has been researched by using UTB-500 uranium isotope reference material and multi-collecting technique. The results show that the nonlinearity effect of SEM exists in the whole ion counting range, and there is an extreme point of the nonlinearity when the ion counting rate is about 20000 cps. The deviation between measured value of the extreme point and the reference value of the reference sample can be up to 3%, and the nonlinearity obeys logarithm linearity law on both sides of extreme point. A kind of mathematics model of nonlinearity calibration has been put forward. Using this model, the nonlinearity of SEM of TIMS can be calibrated. (authors)

  1. Exponential decay and exponential recovery of modal gains in high count rate channel electron multipliers

    International Nuclear Information System (INIS)

    Hahn, S.F.; Burch, J.L.

    1980-01-01

    A series of data on high count rate channel electron multipliers revealed an initial drop and subsequent recovery of gains in exponential fashion. The FWHM of the pulse height distribution at the initial stage of testing can be used as a good criterion for the selection of operating bias voltage of the channel electron multiplier

  2. Investigation of the Decelerating Field of an Electron Multiplier under Negative Ion Impact

    DEFF Research Database (Denmark)

    Larsen, Elfinn; Kjeldgaard, K.

    1973-01-01

    The effect of the decelerating field of an electron multiplier towards negative ions was investigated under standard mass spectrometric conditions. Diminishing of this decelerating field by changing of the potential of the electron multiplier increased the overall sensitivity to negative ions...

  3. Ionizing device comprising a microchannel electron multiplier with secondary electron emission

    International Nuclear Information System (INIS)

    Chalmeton, Vincent.

    1974-01-01

    The present invention relates to a ionizing device comprising a microchannel electron multiplier involving secondary electron emission as a means of ionization. A system of electrodes is used to accelerate said electrons, ionize the gas and extract the ions from thus created plasma. Said ionizer is suitable for bombarding the target in neutron sources (target of the type of nickel molybdenum coated with tritiated titanium or with a tritium deuterium mixture) [fr

  4. GEM applications outside high energy physics

    CERN Document Server

    Duarte Pinto, Serge

    2013-01-01

    From its invention in 1997, the Gas Electron Multiplier has been applied in nuclear and high energy physics experiments. Over time however, other applications have also exploited the favorable properties of GEMs. The use of GEMs in these applications will be explained in principle and practice. This paper reviews applications in research, beam instrumentation and homeland security. The detectors described measure neutral radiations such as photons, x-rays, gamma rays and neutrons, as well as all kinds of charged radiation. This paper provides an overview of the still expanding range of possibilities of this versatile detector concept.

  5. Effect of the channel electron multiplier connection diagram on its parameters

    International Nuclear Information System (INIS)

    Ajnbund, M.R.

    1976-01-01

    Basic alternatives of connection of a channel electron multiplier are described. A dependence of a gain factor and amplitude resolution of the channel electron multiplier upon its connection diagram is studied. The studies have shown that the maximum gain factor is typical of an open-output circuit where the signal is recorded from the anode of the channel electron multiplier at a potential with respect to the channel outlet. The highest amplitude resolution is inherent in a separate-anode circuit where the loading resistance is connected directly to the channel outlet

  6. Sheath formation of a plasma containing multiply charged ions, cold and hot electrons, and emitted electrons

    International Nuclear Information System (INIS)

    You, H.J.

    2012-01-01

    It is quite well known that ion confinement is an important factor in an electron cyclotron resonance ion source (ECRIS) as it is closely related to the plasma potential. A model of sheath formation was extended to a plasma containing multiply charged ions (MCIs), cold and hot electrons, and secondary electrons emitted either by MCIs or hot electrons. In the model, a modification of the 'Bohm criterion' was given, the sheath potential drop and the critical emission condition were also analyzed. It appears that the presence of hot electrons and emitted electrons strongly affects the sheath formation so that smaller hot electrons and larger emission current result in reduced sheath potential (or floating potential). However the sheath potential was found to become independent of the emission current J when J > J c , (where J c is the critical emission current. The paper is followed by the associated poster

  7. Utilization of a channel electron multiplier for counting-measurement on condensed molecular jet

    International Nuclear Information System (INIS)

    Le Bihan, A.M.; Bottiglioni, F.; Coutant, J.; Fois, M.; CEA Centre d'Etudes Nucleaires de Fontenay-aux-Roses, 92

    1974-01-01

    A channel electron multiplier has been used for counting ionized clusters containing up to a few thousands molecules; clusters are accelerated towards a negative (approximately-220V) copper target; a larger negative bias (approximately-3000V) is applied to the multiplier entrance so as to collect positive secondary ions and/or reflected cluster fragments; in the present application this gives better signal to noise ratio than detecting clusters directly or by secondary electron emission on the target [fr

  8. Electronic de-multipliers II (ring-shape systems); Demultiplieurs electroniques II (systeme en anneau)

    Energy Technology Data Exchange (ETDEWEB)

    Raievski, V

    1948-09-01

    This report describes a new type of ring-shape fast electronic counter (de-multiplier) with a resolution capacity equivalent to the one made by Regener (Rev. of Scientific Instruments USA 1946, 17, 180-89) but requiring two-times less electronic valves. This report follows the general description of electronic de-multipliers made by J. Ailloud (CEA--001). The ring comprises 5 flip-flop circuits with two valves each. The different elements of the ring are calculated with enough details to allow the transfer of this calculation to different valve types. (J.S.)

  9. GEM-based gaseous photomultipliers for UV and visible photon imaging

    International Nuclear Information System (INIS)

    Moermann, D.; Balcerzyk, M.; Breskin, A.; Chechik, R.; Singh, B.K.; Buzulutskov, A.

    2003-01-01

    We present the current status of our research on GEM-based gaseous photomultipliers. Detectors combining multi-GEM electron multipliers with semi-transparent and reflective photocathodes are discussed. We present recent progress in extending the sensitivity of these detectors into the visible range. We demonstrate the long-term stability of an argon-sealed bi-alkali photo-diode and provide preliminary results of a gas-sealed Kapton-GEM detector with a bi-alkali photocathode. The problem of ion-induced secondary electron emission is addressed

  10. High dynamic range isotope ratio measurements using an analog electron multiplier

    Czech Academy of Sciences Publication Activity Database

    Williams, P.; Lorinčík, Jan; Franzreb, K.; Herwig, R.

    2013-01-01

    Roč. 45, č. 1 (2013), s. 549-552 ISSN 0142-2421 R&D Projects: GA MŠk ME 894 Institutional support: RVO:67985882 Keywords : Isotope ratios * electron multiplier * dynamic range Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.393, year: 2013

  11. Colliding beam studies of electron detachement from H- by multiply-charged ions

    International Nuclear Information System (INIS)

    Melchert, F.; Benner, M.; Kruedener, S.; Schulze, R.; Meuser, S.; Pfaff, S.; Petri, S.; Huber, K.; Salzborn, E.; Presnyakov, L.P.; Uskov, D.B.

    1993-01-01

    Employing the crossed-beams technique, we have investigated electron-detachment processes from H - in collisions with multiply-charged noble gas ions A q+ . Absolute cross sections for single- and double-electron removal have been measured at center-of-mass energies from 50 keV to 200 keV and charge states q up to 8

  12. Development of triple GEM detector for a heavy ion physics experiment

    International Nuclear Information System (INIS)

    Bhardwaj, A.; Biswal, K.; Gupta, R.

    2015-01-01

    Building and testing of micro-pattern gas detector such as Gas Electron Multiplier (GEM) for several upcoming High-Energy Physics (HEP) experiment projects, is an advance area of research in the field of detector development. We have carried out the long-term stability test and the uniformity of the relative gain over a GEM detector. The method of long-term test and uniformity of the relative gain and the results are presented in this article

  13. Electron capture to autoionizing states of multiply charged ions

    International Nuclear Information System (INIS)

    Mack, E.M.

    1987-01-01

    The present thesis investigates electron capture reactions resulting from slow collisions (V q+ ) and neutral gas targets (B). The energy spectra of the emitted electrons are measured; detection angle is 50 0 . Mainly, autoionizing double capture resulting from collisions with two-electron targets (He, H 2 ) is studied; then, the emitted electrons stem from doubly excited projectile states. The projectiles used are bare C 6+ , the H-like and He-like ions of C, N and O, He-like Ne 8+ and Ne-like Ar 8+ . Excited metastable projectiles used are C 5+ (2s), He-like projectiles A q+ (1s2s 3 S) and Ar 8+ (...2p 5 3s). Comparison is made with the predictions of a recently proposed extended classical barrier model, that was developed in connection with the work. This model assumes sequential capture of the electrons ('two-step' process); it predicts the realized binding enegies of the captured electrons - which may be directly determined from the autoionization spectra using only the projectile charge, the ionization potentials of the target and the collision velocity as parameters. No adjustable parameter enters into the calculations. The term energies and decay modes of the highly excited product ions themselves are studied. Generally, the autoionizing decay of these states is found to proceed preferentially to the directly adjacent lower singly excited state. Experimental evidence is presented, that triply excited states decay by successive emission of two electrons, whenever this is energetically possible. Finally, the L-MM decay in few-electron systems is considered. 314 refs.; 96 figs.; 29 tabs

  14. Prototype sector magnets for the GeV electron microtron (GEM)

    International Nuclear Information System (INIS)

    Wehrle, R.B.; Norem, J.H.; Praeg, W.F.; Swanstrom, R.H.; Thompson, K.M.

    1983-01-01

    Three prototypes of the sector magnets for GeV Electon Microtron accelerators have been designed. One has been built and two are being constructed. The first is a full scale, 168 ton prototype for one-half of a 2 GeV Double Sided Microtron (DSM) sector magnet. The successful fabrication and testing of the pole pieces for this prototype has demonstrated that their required close tolerances for flatness and parallelism can be met. The second magnet is an approximate two-thirds scale model of one step at the low energy end of the hexatron sector magnet designed for the 4 GeV Electron Microtron (GEM). The measured fields demonstrate that the field falls off faster than an Enge-short-tail and error fields are at low levels and are controllable. A third prototype magnet exactly duplicates the full scale geometry of the first three full orbits of the GEM sector magnet from entrance to exit points. It will permit high precision measurements and corrections of field errors and verify the 3-D computer program, TOSCA

  15. Electronic shell structure in multiply charged silver clusters

    International Nuclear Information System (INIS)

    Kandler, O.; Athanassenas, K.; Echt, O.; Kreisle, D.; Leisner, T.; Recknagel, E.

    1991-01-01

    Silver clusters are generated by standard laser vaporization technique and ionized via multiphoton ionization. Time-of-flight mass spectrometry reveals singly, doubly and triply charged clusters, Ag n z+ (z=1, 2, 3). The spectra show, for all charge states, intensity variations, indicating enhanced stabilities for cluster sizes with closed electronic configurations in accord with the spherical jellium model. (orig.)

  16. GEM-based thermal neutron beam monitors for spallation sources

    International Nuclear Information System (INIS)

    Croci, G.; Claps, G.; Caniello, R.; Cazzaniga, C.; Grosso, G.; Murtas, F.; Tardocchi, M.; Vassallo, E.; Gorini, G.; Horstmann, C.; Kampmann, R.; Nowak, G.; Stoermer, M.

    2013-01-01

    The development of new large area and high flux thermal neutron detectors for future neutron spallation sources, like the European Spallation Source (ESS) is motivated by the problem of 3 He shortage. In the framework of the development of ESS, GEM (Gas Electron Multiplier) is one of the detector technologies that are being explored as thermal neutron sensors. A first prototype of GEM-based thermal neutron beam monitor (bGEM) has been built during 2012. The bGEM is a triple GEM gaseous detector equipped with an aluminum cathode coated by 1μm thick B 4 C layer used to convert thermal neutrons to charged particles through the 10 B(n, 7 Li)α nuclear reaction. This paper describes the results obtained by testing a bGEM detector at the ISIS spallation source on the VESUVIO beamline. Beam profiles (FWHM x =31 mm and FWHM y =36 mm), bGEM thermal neutron counting efficiency (≈1%), detector stability (3.45%) and the time-of-flight spectrum of the beam were successfully measured. This prototype represents the first step towards the development of thermal neutrons detectors with efficiency larger than 50% as alternatives to 3 He-based gaseous detectors

  17. How to reduce the ion feedback in GEM

    International Nuclear Information System (INIS)

    Park, S. H.; Kang, S. M.; Kim, Y. G.

    2003-01-01

    The feedback of positive ions in Gas Electron Multiplier(GEM) has to be suppressed to reduce the photocathode degradation in GEM photomultiplier and to prevent the field distortion in a Time Projection Chamber(TPC). The ion feedback dependency on the drift electric field, the transfer field, the asymmetry in the voltages across the GEM, and the effective gain was measured in various gases. The ion feedback is sensitive to the drift field and the effective gain. A model prediction of the ion feedback in multiple GEM was compared with the measurement. The ion gating method, which is being studyed in TPC, is introduced to reduce the ion feedback in GEM. With Maxwell and Garfield calculation, we obtained the reduction of the ion feedback by placing the wires between the drift plate and the GEM. We calculated the depedency of the ion feedback with respect to the bias voltage on the wire, the distance between the wires, and the distance between the wire and the GEM

  18. Studies of collision mechanisms in electron capture by slow multiply charged ions

    International Nuclear Information System (INIS)

    Gilbody, H B; McCullough, R W

    2004-01-01

    We review measurements based on translational energy spectroscopy which are being used to identify and assess the relative importance of the various collision mechanisms involved in one-electron capture by slow multiply charged ions in collisions with simple atoms and molecules

  19. Database for inelastic collisions of lithium atoms with electrons, protons, and multiply charged ions

    NARCIS (Netherlands)

    Schweinzer, J; Brandenburg, R; Bray, [No Value; Hoekstra, R; Aumayr, F; Janev, RK; Winter, HP

    New experimental and theoretical cross-section data for inelastic collision processes of Li atoms in the ground state and excited states (up to n = 4) with electrons, protons, and multiply charged ions have been reported since the database assembled by Wutte et al. [ATOMIC DATA AND NUCLEAR DATA

  20. Electron and X-ray emission in collisions of multiply charged ions and atoms

    International Nuclear Information System (INIS)

    Woerlee, P.H.

    1979-01-01

    The author presents experimental results of electron and X-ray emission following slow collisions of multiply charged ions and atoms. The aim of the investigation was to study the mechanisms which are responsible for the emission. (G.T.H.)

  1. Development, characterization and qualification of first GEM foils produced in India

    Science.gov (United States)

    Shah, Aashaq; Ahmed, Asar; Gola, Mohit; Sharma, Ram Krishna; Malhotra, Shivali; Kumar, Ashok; Naimuddin, Md.; Menon, Pradeep; Srinivasan, K.

    2018-06-01

    The increasing demand for Gas Electron Multiplier (GEM) foils has been driven by their application in many current and proposed high-energy physics experiments. Micropack, a Bengaluru-based company, has established and commercialized GEM foils for the first time in India. Micropack used the double-mask etching technique to successfully produce 10 cm × 10 cm GEM foil. In this paper, we report on the development as well as the geometrical and electrical properties of these foils, including the size uniformity of the holes and leakage current measurements. Our characterization studies show that the foils are of good quality and satisfy all the necessary quality control criteria.

  2. Study of spatial resolution of coordinate detectors based on Gas Electron Multipliers

    Science.gov (United States)

    Kudryavtsev, V. N.; Maltsev, T. V.; Shekhtman, L. I.

    2017-02-01

    Spatial resolution of GEM-based tracking detectors is determined in the simulation and measured in the experiments. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting of atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing with accounting of diffusion, gas amplification fluctuations, distribution of signals on readout electrodes, electronics noise and particular algorithm of final coordinate calculation (center of gravity). The simulation demonstrates that the minimum of spatial resolution of about 10 μm can be achieved with a gas mixture of Ar -CO2 (75-25 %) at a strips pitch from 250 μm to 300 μm. At a larger pitch the resolution quickly degrades reaching 80-100 μm at a pitch of 460-500 μm. Spatial resolution of low-material triple-GEM detectors for the DEUTERON facility at the VEPP-3 storage ring is measured at the extracted beam facility of the VEPP-4 M collider. One-coordinate resolution of the DEUTERON detector is measured with electron beam of 500 MeV, 1 GeV and 3.5 GeV energies. The determined value of spatial resolution varies in the range from approximately 35 μm to 50 μm for orthogonal tracks in the experiments.

  3. Uniformity studies in large area triple-GEM based detectors

    Energy Technology Data Exchange (ETDEWEB)

    Akl, M. Abi [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar); Bouhali, O., E-mail: othmane.bouhali@qatar.tamu.edu [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar); Qatar Computing Research Institute, Hamad Bin Khalifa University, PO Box 5825, Doha (Qatar); Castaneda, A.; Maghrbi, Y.; Mohamed, T. [Science Program, Texas A& M University at Qatar, PO Box 23874, Doha (Qatar)

    2016-10-01

    Gas Electron Multiplier (GEM) based detectors have been used in many applications since their introduction in 1997. Large areas, e.g. exceeding 30×30 cm{sup 2}, of GEM detectors are foreseen in future experiments which puts stringent requirements on the uniformity of response across the detection area. We investigate the effect of small variations of several parameters that could affect the uniformity. Parameters such as the anode pitch, the gas gap, the size and the shape of the holes are investigated. Simulation results are presented and compared to previous experimental data.

  4. Investigations on Important Properties of the 10 cm x 10 cm GEM Prototype

    CERN Document Server

    Saenboonruang, Kiadtisak; Kulasri, Kittipong; Ritthirong, Anawat

    2015-01-01

    The Gas Electron Multiplier (GEM) detector is one of promising particle and radiation detectors that has been improved greatly from previous gas detectors. The improvement includes better spatial resolutions, higher detection rate capabilities, and flexibilities in designs. In particular, the 10 cm x 10 cm GEM prototype is designed and provided by the Gas Detectors Development group (GDD) at CERN, Switzerland. With its simplicity in operations and designs, while still maintaining high qualities, the GEM prototype is suitable for both start-up and advanced researches. This article aims to report the investigations on some important properties of the 10 cm x 10 cm GEM detector using current measurement and signal counting. Results have shown that gains of the GEM prototype exponentially increase as voltage supplied to the detector increases, while the detector reaches full efficiency (plateau region) when the voltage is greater than 4100 V. In terms of signal sharing between X and Y strips of the readout, X str...

  5. GEM - A novel gaseous particle detector

    CERN Document Server

    Meinschad, T

    2005-01-01

    The work carried out within the framework of this Ph.D. deals with the construction of gaseous prototype detectors using Gas Electron Multiplier electrodes for the amplification of charges released by ionizing particles. The Gas Electron Multiplier (GEM) is a thin metal-clad polymer foil, etched with a high density of narrow holes, typically 50-100mm-2. On the application of a potential difference between the conductive top and bottom sides each hole acts as independent proportional counter. This new fast device permits to reach large amplification factors at high rates with a strong photon and ion-mediated feedback suppression due to the avalanche confinement in the GEM-holes. Here, in particular studies have been performed, which should prove, that the GEM-technology is applicable for an efficient measurement of single Cherenkov photons. These UV-photons can be detected in different ways. An elegant solution to develop large area RICH-detectors is to evaporate a pad-segmented readout-cathode of a multi-wire...

  6. Electron loss from multiply protonated lysozyme ions in high energy collisions with molecular oxygen

    DEFF Research Database (Denmark)

    Hvelplund, P; Nielsen, SB; Sørensen, M

    2001-01-01

    We report on the electron loss from multiply protonated lysozyme ions Lys-Hn(n)+ (n = 7 - 17) and the concomitant formation of Lys-Hn(n+1)+. in high-energy collisions with molecular oxygen (laboratory kinetic energy = 50 x n keV). The cross section for electron loss increases with the charge state...... of the precursor from n = 7 to n = 11 and then remains constant when n increases further. The absolute size of the cross section ranges from 100 to 200 A2. The electron loss is modeled as an electron transfer process between lysozyme cations and molecular oxygen....

  7. Timing characteristics of the VEhU-6 microchannel electron multipliers

    International Nuclear Information System (INIS)

    Bakhtizin, R.Z.; Yumaguzin, Yu.M.

    1982-01-01

    The VEhU-6 charnel electron multiplier timing characteristics are experimentally studied. Dependence of monoelectron pulse duration at the VEhU-6 output at different values of channel supply voltage is investigated. The VEhU-6 delay time is measured. Delay time increased from 10 to 30 ns with the increase of channel supply voltage from 2.8 to 3.2 kV (at approximately 10 5 pulse/s loading). Delay time increases with loading decrease

  8. On the fast response of charnel electron multipliers in coUnting mode operation

    International Nuclear Information System (INIS)

    Belyaevskij, O.A.; Gladyshev, I.L.; Korobochko, Yu.S.; Mineev, V.I.

    1983-01-01

    Dependences of amplitude distribution of pulses at the outlet of channel electron multipliers (CEM) and effectiveness of monitoring on counting rate at different supply voltages are determined. It is shown that the maximUm counting rate of CEM runs into 6x10 5 s -1 at short-term and 10 5 s -1 at long-term operation using monitoring eqUipment with operation threshold of 2.5 mV

  9. Recent Developments in GEM-Based Neutron Detectors

    International Nuclear Information System (INIS)

    Saenboonruang, K.

    2014-01-01

    The gas electron multiplier (GEM) detector is a relatively new gaseous detector that has been used for less than 20 years. Since the discovery in 1997 by F. Sauli, the GEM detector has shown excellent properties including high rate capability, excellent resolutions, low discharge probability, and excellent radiation hardness. These promising properties have led the GEM detector to gain popularity and attention amongst physicists and researchers. In particular, the GEM detector can also be modified to be used as a neutron detector by adding appropriate neutron converters. With properties stated above and the need to replace the expensive 3 He-based neutron detectors, the GEM-based neutron detector will be one of the most powerful and affordable neutron detectors. Applications of the GEM-based neutron detectors vary from researches in nuclear and particle physics, neutron imaging, and national security. Although several promising progresses and results have been shown and published in the past few years, further improvement is still needed in order to improve the low neutron detection efficiency (only a few percent) and to widen the possibilities for other uses.

  10. High resolution surface scanning of Thick-GEM for single photo-electron detection

    International Nuclear Information System (INIS)

    Hamar, G.; Varga, D.

    2012-01-01

    An optical system for high resolution scanning of TGEM UV photon detection systems is introduced. The structure exploits the combination of a single Au-coated TGEM under study, and an asymmetric MWPC (Close Cathode Chamber) as post-amplification stage. A pulsed UV LED source with emission down to 240 nm has been focused to a spot of 0.07 mm on the TGEM surface, and single photo-electron charge spectra has been recorded over selected two dimensional regions. This way, the TGEM gain (order of 10–100) and TGEM photo-electron detection efficiency is clearly separated, unlike in case of continuous illumination. The surface structure connected to the TGEM photon detection is well observable, including inefficiencies in the holes and at the symmetry points between holes. The detection efficiency as well as the gas gain are fluctuating from hole to hole. The gain is constant in the hexagon around any hole, pointing to the fact that the gain depends on hole geometry, and less on the position where the electron enters. The detection probability map strongly changes with the field strength above the TGEM surface, in relation to the change of the actual surface field configuration. The results can be confronted with position-dependent simulations of TGEM electron transfer and gas multiplication. -- Highlights: ► First demonstration of Thick GEM surface scanning with single photo-electrons. ► Resolution of 0.1 mm is sufficient to identify structures connected to TGEM surface field structure. ► Gain and detection efficiency and separately measurable. ► Detection efficiency is high in a ring around the holes, and gain is constant in the hexagonal collection regions.

  11. High resolution surface scanning of Thick-GEM for single photo-electron detection

    Energy Technology Data Exchange (ETDEWEB)

    Hamar, G., E-mail: hamar.gergo@wigner.mta.hu [Wigner Research Centre for Physics, Budapest (Hungary); Varga, D., E-mail: vdezso@mail.cern.ch [Eoetvoes Lorand University, Budapest (Hungary)

    2012-12-01

    An optical system for high resolution scanning of TGEM UV photon detection systems is introduced. The structure exploits the combination of a single Au-coated TGEM under study, and an asymmetric MWPC (Close Cathode Chamber) as post-amplification stage. A pulsed UV LED source with emission down to 240 nm has been focused to a spot of 0.07 mm on the TGEM surface, and single photo-electron charge spectra has been recorded over selected two dimensional regions. This way, the TGEM gain (order of 10-100) and TGEM photo-electron detection efficiency is clearly separated, unlike in case of continuous illumination. The surface structure connected to the TGEM photon detection is well observable, including inefficiencies in the holes and at the symmetry points between holes. The detection efficiency as well as the gas gain are fluctuating from hole to hole. The gain is constant in the hexagon around any hole, pointing to the fact that the gain depends on hole geometry, and less on the position where the electron enters. The detection probability map strongly changes with the field strength above the TGEM surface, in relation to the change of the actual surface field configuration. The results can be confronted with position-dependent simulations of TGEM electron transfer and gas multiplication. -- Highlights: Black-Right-Pointing-Pointer First demonstration of Thick GEM surface scanning with single photo-electrons. Black-Right-Pointing-Pointer Resolution of 0.1 mm is sufficient to identify structures connected to TGEM surface field structure. Black-Right-Pointing-Pointer Gain and detection efficiency and separately measurable. Black-Right-Pointing-Pointer Detection efficiency is high in a ring around the holes, and gain is constant in the hexagonal collection regions.

  12. Simulation of the dielectric charging-up effect in a GEM detector

    International Nuclear Information System (INIS)

    Alfonsi, M.; Croci, G.; Duarte Pinto, S.; Rocco, E.; Ropelewski, L.; Sauli, F.; Veenhof, R.; Villa, M.

    2012-01-01

    The charging up effect is well-known in detectors containing dielectric materials and it is due to electrons and ions liberated in an avalanche and collected on the dielectric surfaces. In particular in Gas Electron Multiplier (GEM) based detectors, charges can be captured by the Kapton that separates top and bottom electrodes. The collection of a substantial number of charges on the dielectric surfaces induces a modification of the field inside the GEM holes that implies important consequences on some fundamental parameters such as the electron transparency and the effective gain. The correct simulation of this effect opens new ways to the detailed study of the processes that happens in a GEM-based detector and gives the possibility to optimise the GEM geometry in order to avoid it. This paper compares results of the measurements and the simulations, with and without the introduction of the charging-up effect, of the GEM electron transparency in the case of a single GEM detector. The introduction of the charging up effect in the simulation resulted to be crucial in order to get the proper agreement with the measurements. The measurements and simulations of the GEM effective gain will be the subject of a future work.

  13. CMS GEM detector material study for the HL-LHC

    CERN Document Server

    Muhammad, Saleh

    2017-01-01

    A study on the Gaseous Electron Multiplier (GEM) foil material is performed to determine the moisture diffusion rate and saturation level and the moisture effects on its mechanical properties. The study is focused on the foil contact with ambient air and moisture to determine the value of the diffusion coefficient of water in the detector polyimide. The presence of water inside the detector foil can determine the changes in its mechanical and electrical properties. A simulated model is developed by taking into account the real GEM foil (hole dimensions, shapes and material), which describes the adsorption on a sample. This work describes the model, its experimental verification, the water diffusion within the entire sheet geometry of the GEM foil, thus gaining concentration profiles and the time required to saturate the system and the effects on the mechanical properties.

  14. Development of single mask GEM foils in India

    International Nuclear Information System (INIS)

    Pant, L.M.; Mohanty, A.K.; Pinto, O.J.; Gadhadharan, S.; Menon, Pradeep; Sharma, Archana; Oliveira, Rui De; )

    2014-01-01

    There are various techniques available around the globe for making punch through holes for Micro Pattern Gas Detectors (MPGDs), such as Gas Electron Multipliers (GEMs). The GEM foils consists of 5 μm of Cu clad on both the sides of 50 μm polymide (PMMA/kapton) (5/50/5). At present these foils are developed in South Korea without having any adhesive between the Cu and polymide. The available techniques range from chemical etching, reactive plasma etching and laser etching. However, for GEM detectors, having an active area upto 5000 cm 2 , the chemical etching process using a Single Mask has been developed at CERN which is faster from the viewpoint of mass production of such foils for the upgrades which are foreseen in a couple of years with the Large Hadron Collider facility at CERN

  15. Indirect mechanisms in electron-impact ionization of multiply charged ions

    International Nuclear Information System (INIS)

    Phaneuf, R.A.; Gregory, D.C.

    1986-09-01

    The important role of indirect-ionization mechanisms in electron-impact ionization of multiply charged ions has been emphasized by some recent experiments conducted with the ORNL-ECR multicharged ion source. Illustrative examples of investigations of the Mg-isoelectronic and Fe-isonuclear sequences are presented and compared with the results of detailed theoretical calculations. New experimental data is also presented concerning the role of resonance effects in the ionization of Li-like O 5+ and Na-like Fe 15+ ions

  16. A zerotime detector for nuclear fragments using channel electron multiplier plates

    International Nuclear Information System (INIS)

    Sundqvist, B.

    1975-01-01

    The literature on zerotime detectors which use the emission of secondary electrons from a thin foil is reviewed. The construction of a zerotime detector using multiplication of the secondary electrons with two Mullard channel electron multiplier plates (CEMP) in tandem is described. Results of tests of such a detector with α particles from a natural α source are given. Total time resolutions of about 200 ps (FWHM) with a Si(Sb) detector as the stop detector has been achieved. The contribution from the zerotime detector is estimated to be less than 150 ps (FWHM). The application of this detector technique to the construction of a heavy-ion spectrometer and a 8 Be detector is described. (Auth)

  17. Fine-pitch glass GEM for high-resolution X-ray imaging

    International Nuclear Information System (INIS)

    Fujiwara, T.; Toyokawa, H.; Mitsuya, Y.

    2016-01-01

    We have developed a fine-pitch glass gas electron multiplier (G-GEM) for high-resolution X-ray imaging. The fine-pitch G-GEM is made of a 400 μm thick photo-etchable glass substrate with 150 μm pitch holes. It is fabricated using the same wet etching technique as that for the standard G-GEM. In this work, we present the experimental results obtained with a single fine-pitch G-GEM with a 50 × 50 mm 2 effective area. We recorded an energy resolution of 16.2% and gas gain up to 5,500 when the detector was irradiated with 5.9 keV X-rays. We present a 50 × 50 mm 2 X-ray radiograph image acquired with a scintillation gas and optical readout system.

  18. Discriminating cosmic muons and X-rays based on rise time using a GEM detector

    Science.gov (United States)

    Wu, Hui-Yin; Zhao, Sheng-Ying; Wang, Xiao-Dong; Zhang, Xian-Ming; Qi, Hui-Rong; Zhang, Wei; Wu, Ke-Yan; Hu, Bi-Tao; Zhang, Yi

    2016-08-01

    Gas electron multiplier (GEM) detectors have been used in cosmic muon scattering tomography and neutron imaging over the last decade. In this work, a triple GEM device with an effective readout area of 10 cm × 10 cm is developed, and a method of discriminating between cosmic muons and X-rays based on rise time is tested. The energy resolution of the GEM detector is tested by 55Fe ray source to prove the GEM detector has a good performance. Analysis of the complete signal-cycles allows us to get the rise time and pulse heights. The experiment result indicates that cosmic muons and X-rays can be discriminated with an appropriate rise time threshold. Supported by National Natural Science Foundation of China (11135002, 11275235, 11405077, 11575073)

  19. Gas amplification properties of GEM foils; Gasverstaerkungseigenschaften von GEM-Folien

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Jeannine

    2009-01-15

    procedure were developed and a laser-measurement arrangement for the measurement of GEM surface profiles designed and tested. The Planeness of framed GEM foils was determined, whereby height differences up to 1 mm resulted. [German] Im Rahmen des Detektorkonzeptes International Linear Detector fuer das kuenftige Beschleunigerprojekt International Linear Collider, an dem Elektronen und Positronen bei Schwerpunktsenergien von 500 GeV zur Kollision gebracht werden, soll eine Zeit-Projektions-Kammer als zentrale Spurkammer eingesetzt werden. Mit der Verwendung einer derartigen Kammer als Spurdetektor ist eine dreidimensionale Rekonstruktion der Spurpunkte moeglich. Durchfliegt ein Teilchen das Gasvolumen innerhalb der Kammer, ionisiert es einzelne Gasatome und die entstandenen Elektronen bewegen sich nach der Verstaerkung in der GEM-Anordnung (engl. Gas Electron Multiplier) zur Anode, so dass eine zweidimensionale Projektion der Teilchenspur moeglich ist. Die dritte Dimension wird aus der Driftzeit der Elektronen errechnet. Die Vorteile dieses Auslesesystems bestehen darin, dass eine bessere Ortsaufloesung als mit einer Vieldraht-Proportional-Kammer erreicht wird und die rueckdriftenden Ionen stark unterdrueckt werden koennen. Ziel dieser Arbeit sind Untersuchungen fuer ein GEM-Modul, das in einem grossen TPCPrototypen genutzt werden soll. Hinsichtlich verschiedener Anforderungen gilt es unterschiedliche GEMs zu vergleichen, um eine optimale Auswahl treffen zu koennen. In einem am DESY vorhandenen kleinen Prototypen wurden Messungen zur Erfassung von GEM-beschreibenden Parametern durchgefuehrt. Die Inbetriebnahme der Test-TPC war Bestandteil dieser Arbeit. Es wurden Spuren durch eine radioaktive Quelle erzeugt, mit deren Hilfe die Gasverstaerkung bestimmt wurde. Mit dem Messaufbau wurden verschiedenartige Gasverstaerkerfolien hinsichtlich ihrer Verstaerkungseigenschaften und ihres Energieaufloesungsvermoegens verglichen und systematisch studiert. Es wurden fuenf

  20. New gas electron-multiplier detectors for the endcap muon system of the CMS experiment at the high-luminosity LHC design and prototype performance

    CERN Document Server

    Gruchala, Marek Michal

    2016-01-01

    The high luminosity LHC will require new detectors in the CMS endcap muon system to suppress the trigger rate of background events, to maintain high trigger efficiency for low transverse momentum muons, to enhance the robustness of muon detection in the high-flux environment of the endcap, and to extend the geometrical acceptance. We report on the design and recent progress towards implementing a new system of large-area, triple-foil gas electron-multiplier (GEM) detectors that will be installed in the first three of five muon detector stations in each endcap, the first station being closest to the interaction point. The first station will extend the geometric acceptance in pseudo-rapidity to eta lt 3.0 from the current limit of eta lt 2.4. The second and third stations will enhance the performance in the range 1.6 lt eta lt 2.4. We describe the design of the chambers and readout electronics and report on the performance of prototype systems in tests with cosmic ray muons, high-energy particlebeams, a...

  1. Coupled-Multiplier Accelerator Produces High-Power Electron Beams for Industrial Applications

    International Nuclear Information System (INIS)

    Hatridge, M.; McIntyre, P.; Roberson, S.; Sattarov, A.; Thomas, E.; Meitzler, Charles

    2003-01-01

    The coupled multiplier is a new approach to efficient generation of MeV d.c. power for accelerator applications. High voltage is produced by a series of modules, each of which consists of a high-power alternator, step-up transformer, and 3-phase multiplier circuit. The alternators are connected mechanically along a rotating shaft, and connected by insulating flexible couplers. This approach differs from all previous d.c. technologies in that power is delivered to the various stages of the system mechanically, rather than through capacitive or inductive electrical coupling. For this reason the capital cost depends linearly on required voltage and power, rather than quadratically as with conventional technologies. The CM technology enables multiple electron beams to be driven within a common supply and insulating housing. MeV electron beam is extremely effective in decomposing organic contaminants in water. A 1 MeV, 100 kW industrial accelerator using the CM technology has been built and is being installed for treatment of wastewater at a petrochemical plant

  2. Analysis of microwave amplifier and frequency multiplier tube with a multipactor electron gun

    International Nuclear Information System (INIS)

    Yokoo, Kuniyoshi; Ono, Shoichi; Tai, Dong-Zhe.

    1983-01-01

    The performance analysis was made for a multipactor microwave tube with the aim of realizing a microwave amplifier or a frequency multiplier tube with a multipactor cathode with high efficiency and high power. The possibility for producing the multipactor tube with high efficiency and high power was shown by using effectively the characteristics of the multipactor cathode which emits pulsed electron current with narrow band, synchronizing with high frequency period. As the operating conditions for the multipactor cathode, it was shown that the wide spacing of the cathode was needed for the operation in high operating power, and the narrow spacing was needed for the operation in high efficiency and for reducing power consumption. It was also shown that there were the best values of the high-frequency voltage for the cathode operation. The study by the simulation for the multipactor cathode and for the acceleration zone of electron current was also performed to examine the possible performance for a microwave amplifier and a frequency multiplier tube. For the use of the multipactor cathode with a spacing of 1 mm, the conversion efficiency for d. c. input power was 86, 56 and 31 % for the primary, the secondary and the tertiary harmonic wave amplifications, respectively. (Asami, T.)

  3. Testing of Track Point Resolution of Gas Electron Multiplier with Pion Beam at CERN SPS

    CERN Document Server

    Adak, R P; Das, S; Dubey, A K; Ganti, M S; Saini, J; Singaraju, R

    2015-01-01

    A muon detection system using segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments to be held at GSI, Darmstadt, Germany. The muon detector system is mounted downstream of a Silicon Tracking System. The reconstructed tracks from the STS are to be matched to the hits in the GEM detector. For reconstructing track in the GEM Detector, track point resolution is an important issue. We report her first time the track point resolution of the GEM detector.

  4. Testing of self-triggered nXYTER electronics for integrating with GEM detector for high frequency operation

    International Nuclear Information System (INIS)

    Saini, J.; Dubey, A.K.; Chattopadhyay, S.; Singaraju, R.N.

    2013-01-01

    A GEM-based tracking system is planned to be used for muon tracking in the proposed CBM experiment at FAIR. The peak hit density in the central region of the chamber is expected to reach 1 MHz/cm 2 . For a detector to be operational at high intensity (upto MHz), it is useful to know the compatibility of the readout electronics with the detector. At very high rates and sufficiently large signal amplitude, there is a possibility of preamplifier saturation resulting in zero or distorted amplitude of the output signal

  5. Detection of X-ray fluorescence of light elements by electron counting in a low-pressure gaseous electron multiplier

    International Nuclear Information System (INIS)

    Pansky, A.; Breskin, A.; Chechik, R.; Malamud, G.

    1992-12-01

    Ionization electrons deposited by soft X-rays in a low pressure (10 Torr) gas medium are efficiently counted by a multistage electron multiplier, providing an accurate measurement of the X-ray photon energy. Energy resolution of 56-28% FWHM were measured for X-rays of 110-676 eV, recording electrical induced charges or visible photons emitted during the avalanche process. It is demonstrated that a combined analysis of the number of electron trail length of an event, provides a powerful and competitive way of resolving ultra soft X-rays. We present the experimental technique, discuss the advantages and limitations of the Primary Electron Counter, and suggest ways to improve its performances. (authors)

  6. Data acquisition and online control system for new gas-electron multiplier detectors in the endcap muon system of the CMS experiment

    CERN Document Server

    Ruiz Alvarez, Jose David

    2016-01-01

    A new data acquisition and on-line control system is being developed for gas-electron multiplier (GEM) detectors which will be installed in the forward region (1.6 \\( < \\eta < \\) 2.2) of the CMS muon spectrometer during the 2nd long shutdown of the LHC, planned for the period 2018-2019. A prototype system employs the TOTEM VFAT2 ASIC that will eventually be replaced with the VFAT3 ASIC, under development. The front-end ASIC communicates over printed circuit lines with an intermediate on-detector board called the opto-hybrid. Data, trigger, and control information is transmitted via optical fiber between the opto-hybrid and an off-detector readout system using micro-TCA technology. On-line software, implemented in the CMS XDAQ framework, includes applications for latency and HV scans, and system management. We report on the operational status of the prototype system that has been tested using cosmic ray muons and extracted high-energy particle beams. This work is preparatory for the operation of a prot...

  7. Removal of contaminating tritium and tritium pressure measurement by a secondary electron multiplier

    International Nuclear Information System (INIS)

    Ichimura, K.; Watanabe, K.; Nishizawa, K.; Fujita, J.

    1984-01-01

    A ceramic secondary electron multiplier (SEM), Ceratron, was used to study impairment of the SEM performance due to adsorbed tritium, its decontamination, and the applicability of the SEM to measure tritium pressure. The background level of the SEM increased significantly, up to its counting limit, due to tritium adsorption. Heating it to 300 0 C in vacuo and/or in the presence of reactive gases such as D 2 and CO at 1 x 10 -4 Pa was not effective to decontaminate the SEM, whereas photon irradiation was extremely powerful for the decontamination. The tritium (HT) pressure in a range of 1 x 10 -6 - 1 x 10 -3 Pa could be measured with no significant impairment of the SEM performance with the aid of photon irradiation. It is revealed that a particle flux as low as 1 particle/s will be able to measure in the presence of tritium if suitable photon sources are installed in the systems. (orig.)

  8. Performance test of a micro-pattern stereo detector with two gas electron multipliers

    International Nuclear Information System (INIS)

    Barvich, T.; Bluem, P.; Erdmann, M.; Fahrer, M.; Kaercher, K.; Kuehn, F.; Moermann, D.; Mueller, Th.; Neuberger, D.; Roederer, F.; Simonis, H.J.; Skiba, A.; Thuemmel, W.H.; Weiler, Th.; Weseler, S.

    2002-01-01

    We report on the performance of a large micro-pattern detector with two gas electron multiplier foils and a two-layer readout structure at ground potential. The two readout layers each have a 406 μm pitch and cross at an effective angle of 6.7 deg. . This structure allows for two orthogonal coordinates to be determined. Using a muon beam at CERN together with a silicon tracking system, the position resolutions of the two coordinates are measured to be 50 μm and 1 mm respectively (1 standard deviation). The muon detection efficiency for the two-dimensional space points reaches 96%. The detector was found to be well operational over a wide range in the settings of the different electrical fields

  9. Electron cyclotron resonance (E.C.R.) multiply charged ion sources

    International Nuclear Information System (INIS)

    Geller, R.

    1978-01-01

    High charge state ions can be produced by electron bombardment inside targets when the target electron density n (cm -3 ) multiplied by the ion transit time through the target tau (sec) is: n tau > 5.10 9 cm -3 sec. The relative velocity between electrons and ions determines the balance between stripping and capture i.e. the final ion charge state. (In a stripper foil fast ions interact with slow electrons involving typically n approximately 10 24 cm -3 , tau approximately 10 -14 sec). In the E.C.R. source a cold ion plasma created in a first stage diffuses slowly through a second stage containing a hot E.C.R. plasma with n > 3.10 11 cm -3 and tau > 10 -2 sec. Continuous beams of several μA of C 6+ N 7+ Ne 9+ A 11+ are extracted from the second stage with normalized emittances of approximately 0.5 π mm mrad. The absence of cathodes and plasma arcs makes the source very robust, reliable and well-fitted for cyclotron injection. A super conducting source is under development

  10. Quality assurance of GEM foils in the framework of the TPC upgrade in the ALICE experiment

    CERN Document Server

    Ozcelik, Melih Arslan

    2016-01-01

    In the framework of the TPC upgrade of the ALICE Experiment, new readout chambers will be installed during the LHC long shutdown 2, which is scheduled to start in July 2018. The current MWPCs (Multi Wire Proportional Chambers) will be replaced by readout chambers consisting of GEM (Gas Electron Multipliers) foils in order to meet the increasing readout rate requirements. QA (Quality Assurance) tests on the GEMs are performed to classify the foils. In this report we present the work done during the CERN Summer Student Programme 2016.

  11. The TOTEM T2 telescope based on triple-GEM chambers

    CERN Document Server

    Bagliesi, M G; Brucken, E; Cecchi, R; David, E; Garcia, F; Greco, V; Heino, J; Hilden, T; Kurvinen, K; Lauhakangas, R; Lami, S; Latino, G; Magazzu, G; Oliveri, E; Pedreschi, E; Ropelewski, L; Scribano, A; Spinella, F; Turini, N; van Stenis, M

    2010-01-01

    The TOTEM experiment at LHC has chosen the triple Gas Electron Multiplier (GEM) technology for its T2 telescope which will provide charged track reconstruction in the pseudorapidity range 5.3<|η|<6.5 and a fully inclusive trigger for inelastic events. GEMs are gas filled detectors which combine good spatial resolution with very high rate capability and a good resistance to radiation. Preliminary results of cosmic ray tests performed at CERN on final T2 modules before installation are here presented. Comparisons between real and simulated detector performance are also shown.

  12. The TOTEM T2 telescope based on triple-GEM chambers

    Energy Technology Data Exchange (ETDEWEB)

    Bagliesi, M.G., E-mail: mg.bagliesi@pi.infn.i [University of Siena and INFN Pisa (Italy); Berretti, M. [University of Siena and INFN Pisa (Italy); Brucken, E. [Helsinki (Finland); Cecchi, R. [University of Siena and INFN Pisa (Italy); David, E. [CERN, Geneva (Switzerland); Garcia, F. [Helsinki (Finland); Greco, V. [University of Siena and INFN Pisa (Italy); Heino, J.; Hilden, T.; Kurvinen, K.; Lauhakangas, R. [Helsinki (Finland); Lami, S.; Latino, G.; Magazzu, G.; Oliveri, E.; Pedreschi, E. [University of Siena and INFN Pisa (Italy); Ropelewski, L. [CERN, Geneva (Switzerland); Scribano, A.; Spinella, F.; Turini, N. [University of Siena and INFN Pisa (Italy)

    2010-05-21

    The TOTEM experiment at LHC has chosen the triple Gas Electron Multiplier (GEM) technology for its T2 telescope which will provide charged track reconstruction in the pseudorapidity range 5.3<|{eta}|<6.5 and a fully inclusive trigger for inelastic events. GEMs are gas filled detectors which combine good spatial resolution with very high rate capability and a good resistance to radiation. Preliminary results of cosmic ray tests performed at CERN on final T2 modules before installation are here presented. Comparisons between real and simulated detector performance are also shown.

  13. Construction of the TH-GEM detector components for metrology of low energy ionizing radiation

    Energy Technology Data Exchange (ETDEWEB)

    Silva, N.F.; Castro, M.C.; Caldas, L.V.E., E-mail: nsilva@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Silva, T.F.; Luz, H. Natal da [Universidade de São Paulo (IF/USP), São Paulo, SP (Brazil). Instituto de Física

    2017-07-01

    The Gas Electron Multiplier (GEM) detector was originally proposed as a position sensitive detector to determine trajectories of particles prevenient from high energy collisions. In order to study the potential of TH-GEM type detectors in dosimetric applications for low energy X-rays, specifically for the mammography standard qualities, it was proposed to construct a prototype with characteristics suitable for such use. In this work the general, structural and material parameters applicable to the necessary conditions were defined, establishing the process of construction of the components of a prototype. (author)

  14. Construction of the TH-GEM detector components for metrology of low energy ionizing radiation

    International Nuclear Information System (INIS)

    Silva, N.F.; Castro, M.C.; Caldas, L.V.E.; Silva, T.F.; Luz, H. Natal da

    2017-01-01

    The Gas Electron Multiplier (GEM) detector was originally proposed as a position sensitive detector to determine trajectories of particles prevenient from high energy collisions. In order to study the potential of TH-GEM type detectors in dosimetric applications for low energy X-rays, specifically for the mammography standard qualities, it was proposed to construct a prototype with characteristics suitable for such use. In this work the general, structural and material parameters applicable to the necessary conditions were defined, establishing the process of construction of the components of a prototype. (author)

  15. Construction of the TH-GEM detector components for metrology of low energy ionizing radiation

    Science.gov (United States)

    Silva, N. F.; Silva, T. F.; Castro, M. C.; Natal da Luz, H.; Caldas, L. V. E.

    2018-03-01

    The Gas Electron Multiplier (GEM) detector was originally proposed as a position sensitive detector to determine trajectories of particles prevenient from high-energy collisions. In order to study the potential of TH-GEM type detectors in dosimetric applications for low energy X-rays, specifically for the mammography standard qualities, it was proposed to construct a prototype with characteristics suitable for such use. In this work the general, structural and material parameters applicable to the necessary conditions were defined, establishing the process of construction of the components of a prototype.

  16. Graphics gems

    CERN Document Server

    Glassner, Andrew S

    1993-01-01

    ""The GRAPHICS GEMS Series"" was started in 1990 by Andrew Glassner. The vision and purpose of the Series was - and still is - to provide tips, techniques, and algorithms for graphics programmers. All of the gems are written by programmers who work in the field and are motivated by a common desire to share interesting ideas and tools with their colleagues. Each volume provides a new set of innovative solutions to a variety of programming problems.

  17. Design of data acquisition system for GEM detector

    International Nuclear Information System (INIS)

    Lu Jianliang; Chen Ziyu; Shen Ji; Jin Xi

    2011-01-01

    It describes the design and realization of the USB 2.0 high speed data acquisition devise which is used in the readout electronics of the GEM (gas electron multiplier) detector. By using of the USB Microcontroller EZ-USB FX2 CY7C68013A, high speed ADC and FPGA, high-speed data rate of data acquisition and transmission was realized. The data rate reaches to 20 MByte/s, meeting the requirements of data acquisition and transmission of the detector. (authors)

  18. A time projection chamber with GEM-based readout

    Energy Technology Data Exchange (ETDEWEB)

    Attié, David [CEA Saclay, IRFU, F-91191 Gif-sur-Yvette (France); Behnke, Ties [Deutsches Elektronen-Synchrotron DESY, A Research Centre of the Helmholtz Association, Notkestrasse 85, 22607 Hamburg (Hamburg site) (Germany); Bellerive, Alain [Carleton University, Department of Physics, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6 (Canada); Bezshyyko, Oleg [Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, City of Kyiv 01601 (Ukraine); Bhattacharya, Deb Sankar [CEA Saclay, IRFU, F-91191 Gif-sur-Yvette (France); now at Saha Institute of Nuclear Physics, 1/AF, Sector 1, Bidhan Nagar, Kolkata 700064 (India); Bhattacharya, Purba [Saha Institute of Nuclear Physics, 1/AF, Sector 1, Bidhan Nagar, Kolkata 700064 (India); now at National Institute of Science Education and Research (NISER) Bhubaneswar, P.O. Jatni, Khurda 752050, Odisha (India); Bhattacharya, Sudeb [Saha Institute of Nuclear Physics, 1/AF, Sector 1, Bidhan Nagar, Kolkata 700064 (India); Caiazza, Stefano [Deutsches Elektronen-Synchrotron DESY, A Research Centre of the Helmholtz Association, Notkestrasse 85, 22607 Hamburg (Hamburg site) (Germany); now at Johannes Gutenberg Universität Mainz, Institut für Physik, 55099 Mainz (Germany); Colas, Paul [CEA Saclay, IRFU, F-91191 Gif-sur-Yvette (France); Lentdecker, Gilles De [Inter University ULB-VUB, Av. Fr. Roosevelt 50, B1050 Bruxelles (Belgium); Dehmelt, Klaus [Deutsches Elektronen-Synchrotron DESY, A Research Centre of the Helmholtz Association, Notkestrasse 85, 22607 Hamburg (Hamburg site) (Germany); now at State University of New York at Stony Brook, Department of Physics and Astronomy, Stony Brook, NY 11794-3800 (United States); Desch, Klaus [Universität Bonn, Physikalisches Institut, Nußallee 12, 53115 Bonn (Germany); and others

    2017-06-01

    For the International Large Detector concept at the planned International Linear Collider, the use of time projection chambers (TPC) with micro-pattern gas detector readout as the main tracking detector is investigated. In this paper, results from a prototype TPC, placed in a 1 T solenoidal field and read out with three independent Gas Electron Multiplier (GEM) based readout modules, are reported. The TPC was exposed to a 6 GeV electron beam at the DESY II synchrotron. The efficiency for reconstructing hits, the measurement of the drift velocity, the space point resolution and the control of field inhomogeneities are presented.

  19. Multicascade X-Ray Free-Electron Laser with Harmonic Multiplier and Two-Frequency Undulator

    Science.gov (United States)

    Zhukovsky, K. V.

    2018-06-01

    The feasibility of generation of powerful x-ray radiation by a cascade free-electron laser (FEL) with amplification of higher harmonics using a two-frequency undulator is studied. To analyze the FEL operation, a complex phenomenological single-pass FEL model is developed and used. It describes linear and nonlinear generation of harmonics in the FEL with seed laser that takes into account initial electron beam noise and describes all main losses of each harmonic in each FEL cascade. The model is also calibrated against and approved by the experimental FEL data and available results of three-dimensional numerical simulation. The electron beam in the undulator is assumed to be matched and focused, and the dynamics of power in the singlepass FEL with cascade harmonic multipliers is investigated to obtain x-ray laser radiation in the FEL having the shortest length, beam energy, and frequency of the seed laser as low as possible. In this context, the advantages of the two-frequency undulator used for generation of harmonics are demonstrated. The evolution of harmonics in a multicascade FEL with multiplication of harmonics is investigated. The operation of the cascade FEL at the wavelength λ = 1.14 nm, generating 30 MW already on 38 m with the seed laser operating at a wavelength of 11.43 nm corresponding to the maximal reflectivity of the multilayered mirror MoRu/Be coating is investigated. In addition, the operation of the multicascade FEL with accessible seed UVlaser operating at a wavelength of 157 nm (F2 excimer UV-laser) and electron beam with energy of 0.5 GeV is investigated. X-ray radiation simulated in it at the wavelength λ 3.9 nm reaches power of 50 MW already at 27 m, which is by two orders of magnitude shorter than 3.4 km of the x-ray FEL recently put into operation in Europe.

  20. Triple GEM gas detectors as real time fast neutron beam monitors for spallation neutron sources

    International Nuclear Information System (INIS)

    Murtas, F; Claps, G; Croci, G; Tardocchi, M; Pietropaolo, A; Cippo, E Perelli; Rebai, M; Gorini, G; Frost, C D; Raspino, D; Rhodes, N J; Schooneveld, E M

    2012-01-01

    A fast neutron beam monitor based on a triple Gas Electron Multiplier (GEM) detector was developed and tested for the ISIS spallation neutron source in U.K. The test on beam was performed at the VESUVIO beam line operating at ISIS. The 2D fast neutron beam footprint was recorded in real time with a spatial resolution of a few millimeters thanks to the patterned detector readout.

  1. GEM Foil Quality Assurance For The ALICE TPC Upgrade

    Directory of Open Access Journals (Sweden)

    Brücken Erik

    2018-01-01

    Full Text Available The ALICE (A Large Ion Collider Experiment experiment at the Large Hadron Collider (LHC at CERN is dedicated to heavy ion physics to explore the structure of strongly interacting matter. The Time Projection Chamber (TPC of ALICE is a tracking detector located in the central region of the experiment. It offers excellent tracking capabilities as well as particle identification. After the second long shutdown (LS2 the LHC will run at substantially higher luminosities. To be able to increase the data acquisition rate by a factor of 100, the ALICE TPC experiment has to replace the Multi-Wire Proportional Chamber (MWPC –based readout chambers. The MWPC are operated with gating grid that limits the rate to O(kHz. The new ReadOut Chamber (ROC design is based on Gas Electron Multiplier (GEM technology operating in continuous mode. The current GEM productions scheme foresees the production of more than 800 GEM foils of different types. To fulfill the requirements on the performance of the GEM TPC readout, necessitates thorough Quality Assurance (QA measures. The QA scheme, developed by the ALICE collaboration, will be presented in detail.

  2. GEM Foil Quality Assurance For The ALICE TPC Upgrade

    Science.gov (United States)

    Brücken, Erik; Hildén, Timo

    2018-02-01

    The ALICE (A Large Ion Collider Experiment) experiment at the Large Hadron Collider (LHC) at CERN is dedicated to heavy ion physics to explore the structure of strongly interacting matter. The Time Projection Chamber (TPC) of ALICE is a tracking detector located in the central region of the experiment. It offers excellent tracking capabilities as well as particle identification. After the second long shutdown (LS2) the LHC will run at substantially higher luminosities. To be able to increase the data acquisition rate by a factor of 100, the ALICE TPC experiment has to replace the Multi-Wire Proportional Chamber (MWPC) -based readout chambers. The MWPC are operated with gating grid that limits the rate to O(kHz). The new ReadOut Chamber (ROC) design is based on Gas Electron Multiplier (GEM) technology operating in continuous mode. The current GEM productions scheme foresees the production of more than 800 GEM foils of different types. To fulfill the requirements on the performance of the GEM TPC readout, necessitates thorough Quality Assurance (QA) measures. The QA scheme, developed by the ALICE collaboration, will be presented in detail.

  3. Performance Evaluation of the COBRA GEM for the Application of the TPC

    Science.gov (United States)

    Terasaki, Kohei; Hamagaki, Hideki; Gunji, Taku; Yamaguchi, Yorito

    2014-09-01

    Suppression of the back-drifting ions from avalanche region to drift space (IBF: Ion Backflow) is the key for a Time Projection Chamber (TPC) since IBF easily distorts the drift field. To suppress IBF, Gating Grid system is widely used for the TPC but this limits the data taking rate. Gas Electron Multiplier (GEM) has advantages in the reduction of IBF and high rate capability. By adopting GEM, it is possible to run a TPC continuously under high rate and high multiplicity conditions. Motivated by the study of IBF reduction for RICH with Thick COBRA, which has been developed by F. A. Amero et al., we developed COBRA GEMs for the application of a TPC. With a stack configuration, IBF reaches about 0.1 ~ 0.5%, which is ×5--10 better IBF than the standard GEMs. However, the measured energy resolution with COBRA is 20% (σ) and this is much worse than the resolution with standard GEMs. Measurement of long-time stability of gain indicates that gain of COBRA varies significantly due to charging up effect. Simulation studies based on Garfield++ are performed for understanding quantitatively the reasons of worse energy resolution and instability of gain. In this presentation, we will report the simulation studies together with the measured performance of the COBRA GEM.

  4. A Monte Carlo simulation of the microdosimetric response for thick gas electron multiplier

    International Nuclear Information System (INIS)

    Hanu, A.; Byun, S.H.; Prestwich, W.V.

    2010-01-01

    The neutron microdosimetric responses of the thick gas electron multiplier (THGEM) detector were simulated. The THGEM is a promising device for microdosimetry, particularly for measuring the dose spectra of intense radiation fields and for collecting two-dimensional microdosimetric distributions. To investigate the response of the prototype THGEM microdosimetric detector, a simulation was developed using the Geant4 Monte Carlo code. The simulation calculates the deposited energy in the detector sensitive volume for an incident neutron beam. Both neutron energy and angular responses were computed for various neutron beam conditions. The energy response was compared with the reported experimental microdosimetric spectra as well as the evaluated fluence-to-kerma conversion coefficients. The effects of using non-tissue equivalent materials were also investigated by comparing the THGEM detector response with the response of an ideal detector in identical neutron field conditions. The result of the angular response simulations revealed severe angular dependencies for neutron energies above 100 keV. The simulation of a modified detector design gave an angular response pattern close to the ideal case, showing a fluctuation of less than 10% over the entire angular range.

  5. User's manual for EXALPHA (a code for calculating electronic properties of molecules). [Muscatel code, multiply scattered electron approximation

    Energy Technology Data Exchange (ETDEWEB)

    Jones, H.D.

    1976-06-01

    The EXALPHA procedures provide a simplified method for running the MUSCATEL computer code, which in turn is used for calculating electronic properties of simple molecules and atomic clusters, based on the multiply scattered electron approximation for the wave equations. The use of the EXALPHA procedures to set up a run of MUSCATEL is described.

  6. A large ungated TPC with GEM amplification

    Science.gov (United States)

    Berger, M.; Ball, M.; Fabbietti, L.; Ketzer, B.; Arora, R.; Beck, R.; Böhmer, F. V.; Chen, J.-C.; Cusanno, F.; Dørheim, S.; García, F.; Hehner, J.; Herrmann, N.; Höppner, C.; Kaiser, D.; Kis̆, M.; Kleipa, V.; Konorov, I.; Kunkel, J.; Kurz, N.; Leifels, Y.; Müllner, P.; Münzer, R.; Neubert, S.; Rauch, J.; Schmidt, C. J.; Schmitz, R.; Soyk, D.; Vandenbroucke, M.; Voss, B.; Walther, D.; Zmeskal, J.

    2017-10-01

    A Time Projection Chamber (TPC) is an ideal device for the detection of charged particle tracks in a large volume covering a solid angle of almost 4 π. The high density of hits on a given particle track facilitates the task of pattern recognition in a high-occupancy environment and in addition provides particle identification by measuring the specific energy loss for each track. For these reasons, TPCs with Multiwire Proportional Chamber (MWPC) amplification have been and are widely used in experiments recording heavy-ion collisions. A significant drawback, however, is the large dead time of the order of 1 ms per event generated by the use of a gating grid, which is mandatory to prevent ions created in the amplification region from drifting back into the drift volume, where they would severely distort the drift path of subsequent tracks. For experiments with higher event rates this concept of a conventional TPC operating with a triggered gating grid can therefore not be applied without a significant loss of data. A continuous readout of the signals is the more appropriate way of operation. This, however, constitutes a change of paradigm with considerable challenges to be met concerning the amplification region, the design and bandwidth of the readout electronics, and the data handling. A mandatory prerequisite for such an operation is a sufficiently good suppression of the ion backflow from the avalanche region, which otherwise limits the tracking and particle identification capabilities of such a detector. Gas Electron Multipliers (GEM) are a promising candidate to combine excellent spatial resolution with an intrinsic suppression of ions. In this paper we describe the design, construction and the commissioning of a large TPC with GEM amplification and without gating grid (GEM-TPC). The design requirements have driven innovations in the construction of a light-weight field-cage, a supporting media flange, the GEM amplification and the readout system, which are

  7. A new design using GEM-based technology for the CMS experiment

    Science.gov (United States)

    Ressegotti, M.

    2017-07-01

    The muon system of the Compact Muon Solenoid (CMS) experiment at the LHC is currently not instrumented for pseudorapidity higher than |η|> 2.4. The main challenges to the installation of a detector in that position are the high particle flux to be sustained, a high level of radiation, and the ability to accomodate a multilevel detector into the small available space (less than 30 cm). A new back-to-back configuration of a Gas Electron Multiplier (GEM) detector is presented with the aim of developing a compact, multi-layer GEM detector. It is composed of two independent stacked triple-GEM detectors, positioned with the anodes toward the outside and sharing the same cathode plane, which is located at the center of the chamber, to reduce the total detector's thickness. A first prototype has been produced and tested with an X-Ray source and muon beam. First results on its performance are presented.

  8. A new design using GEM-based technology for the CMS experiment

    CERN Document Server

    Ressegotti, Martina

    2017-01-01

    The muon system of the Compact Muon Solenoid (CMS) experiment at the LHC is currently not instrumented for pseudorapidity higher than abs(${\\eta}$)${ > 2.4}$. The main challenges to the installation of a detector in that position are the high particle flux to be sustained, a high level of radiation, and the ability to accomodate a multilevel detector into the small available space (less than 30 cm). A new back-to-back configuration of a Gas Electron Multiplier (GEM) detector is presented with the aim of developing a compact, multi-layer GEM detector. It is composed of two independent stacked triple-GEM detectors, positioned with the anodes toward the outside and sharing the same cathode plane, which is located at the center of the chamber, to reduce the total detector's thickness. A first prototype has been produced and tested with an X-Ray source and muon beam. First results on its performance are presented.

  9. Performance study of a GEM-TPC prototype using cosmic rays

    International Nuclear Information System (INIS)

    Li Yulan; Qi Huirong; Li Jin; Gao Yuanning; Li Yuanjing; Yang Zhenwei; Fujii, Keisuke; Matsuda, Takeshi

    2008-01-01

    Time projection chambers (TPCs) have been successfully used as the central tracking devices in a number of high-energy physics experiments. However, the performance requirements on TPCs for future high-energy physics experiments greatly exceed the abilities of traditional TPCs read out by multi-wire proportional chambers (MWPCs). Micro-pattern gas detectors (MPGDs), such as gas electron multipliers (GEMs) or micromegas, have great potential to improve TPC performance when used as readout detectors. In order to evaluate its feasibility, a GEM-based TPC prototype with a drift length up to 50 cm was designed. Measurements of the spatial resolution of cosmic-ray tracks without and with a magnetic field (B=1 T) are presented. A very good performance is achieved, matching the analytic formula for the spatial resolution of a MPGD-readout TPC. A dedicated study shows that the increase of GEM detector gain can improve the TPC's spatial resolution.

  10. GEM Detectors in the Experiments at e+e- Colliders in BINP

    CERN Document Server

    Maltsev, T V

    2017-01-01

    Micro-pattern gaseous detectors possess a high spatial resolution in tens micron scale together with high rate capability up to 107 cm-2s-1. In addition, they have all advantages of gaseous detectors, such as relatively low costs per unit area, the possibility to equip a large area as well as a high uniformity. Cascaded Gas Electron Multiplier (GEM) based detectors are used in the collider experiments at Budker Institute of Nuclear Physics (BINP), and they are being developed for a number of new projects. In this article the review of GEM based detectors for the tagging system of the KEDR experiment at the VEPP-4M collider and for the DEUTERON facility at the VEPP-3 storage ring is presented. The GEM detector application of the CMD-3 detector upgrade at the VEPP-2000 collider and the Super τ Factory detector are discussed.

  11. Gas Gain Measurement Of GEM-Foil In Argon-Carbon Dioxide Mixture

    International Nuclear Information System (INIS)

    Nguyen Ngoc Duy; Vuong Huu Tan; Le Hong Khiem

    2011-01-01

    Nuclear reaction measurement with radioactive beam at low energy plays an important role in nuclear astrophysics and nuclear structure. The trajectory of particle beams can be obtained by using an active gas target, multiple-sampling and tracking proportional chamber (MSTPC), as a proportional counter. Because of intensity of low energy radioactive beam, in the stellar reaction such as (α, p), (p, α), it is necessary to increase the gain for the counter. In this case, a gas electrons multiplier (GEM) foil will be used, so the proportional counter is called GEM-MSTPC. The efficient gas gain of GEM foils which relates to foil thickness and operating pressure was investigated with two type of the foils, 400 μm and 200 μm, in Argon (70%) + Carbon dioxide (30%) mixture. (author)

  12. Design of large size segmented GEM foils and Drift PCB for CBM MUCH

    International Nuclear Information System (INIS)

    Saini, J.; Dubey, A.K.; Chattopadhyay, S.

    2016-01-01

    Triple GEM (Gas Electron Multiplier), sector shaped detectors will be used for Muon tracking in the Compressed Baryonic Matter (CBM) experiment at Anti-proton Ion Research (FAIR) facility at Darmstadt, Germany. The sizes of the detectors modules in the Muon Chambers (MUCH) are of the order of 1 meter with active area of about 75cms. Progressive pad geometry is chosen for the readout from these detectors. In construction of these chambers, three GEM foils are stacked on top of each other in a 3/2/2/2 gap configuration. The GEM foils are double layered copper clad 50μm thin Kapton foil. Each GEM foil has millions of holes on it. Foils of large surface area are prone to damages due to discharges owing to the high capacitance of the foil. Hence, these foils have their top surfaces divided into segments of about 100 sq.cm. Further segmentation may be necessary when there are high rate requirements, as in the case of CBM. For the GEM foils of CBM MUCH, a 24 segment layout has been adopted. Short-circuit in any of the GEM-holes will make entire foil un-usable. To reduce such occurrences, segment to segment isolation using opto-coupler in series with the GEM-foil segments has been introduced. Hence, a novel design for GEM chamber drift-PCB and foils has been made. In this scheme, each segment is powered and controlled individually. At the same time, the design takes into account, the space constraints, not only in x-y plane, but also in the z, due to compact assembly of MUCH detector layers

  13. GEM Technical Design Report

    International Nuclear Information System (INIS)

    1993-01-01

    The GEM collaboration was formed in June 1991 to develop a major detector for the SSC. The primary physics objectives of GEM are those central to the motivation for the SSC, to study high p T physics - exemplified by the search for Higgs bosons - and to search for new physics beyond the standard model. The authors present in this Technical Design Report (TDR) a detector with broad capabilities for the discovery and subsequent study of electroweak symmetry breaking, the origin of mass and flavor, and other physics requiring precise measurements of gammas, electrons, and muons - hence the name, GEM. In addition, as a design goal, they have taken care to provide the robustness needed to do the physics that requires high luminosity. Finally, good coverage and hermeticity allow the detection of missing transverse energy, E T . The GEM design emphasizes clean identification and high resolution measurement of the primary physics signatures for high p T physics. The approach is to make precise energy measurements that maximize the sensitivity to rare narrow resonances, to detect the elementary interaction products (quarks, leptons, and photons), and to build in the features required to reduce backgrounds

  14. GEM Technical Design Report

    Energy Technology Data Exchange (ETDEWEB)

    1993-07-31

    The GEM collaboration was formed in June 1991 to develop a major detector for the SSC. The primary physics objectives of GEM are those central to the motivation for the SSC, to study high p{sub T} physics - exemplified by the search for Higgs bosons - and to search for new physics beyond the standard model. The authors present in this Technical Design Report (TDR) a detector with broad capabilities for the discovery and subsequent study of electroweak symmetry breaking, the origin of mass and flavor, and other physics requiring precise measurements of gammas, electrons, and muons - hence the name, GEM. In addition, as a design goal, they have taken care to provide the robustness needed to do the physics that requires high luminosity. Finally, good coverage and hermeticity allow the detection of missing transverse energy, E{sub T}. The GEM design emphasizes clean identification and high resolution measurement of the primary physics signatures for high p{sub T} physics. The approach is to make precise energy measurements that maximize the sensitivity to rare narrow resonances, to detect the elementary interaction products (quarks, leptons, and photons), and to build in the features required to reduce backgrounds.

  15. High voltage distribution scheme for large size GEM detector

    International Nuclear Information System (INIS)

    Saini, J.; Kumar, A.; Dubey, A.K.; Negi, V.S.; Chattopadhyay, S.

    2016-01-01

    Gas Electron Multiplier (GEM) detectors will be used for Muon tracking in the Compressed Baryonic Matter (CBM) experiment at the Facility for Anti-proton Ion Research (FAIR) at Darmstadt, Germany. The sizes of the detector modules in the Muon chambers are of the order of 1 metre x 0.5 metre. For construction of these chambers, three GEM foils are used per chamber. These foils are made by two layered 50μm thin kapton foil. Each GEM foil has millions of holes on it. In such a large scale manufacturing of the foils, even after stringent quality controls, some of the holes may still have defects or defects might develop over the time with operating conditions. These defects may result in short-circuit of the entire GEM foil. A short even in a single hole will make entire foil un-usable. To reduce such occurrences, high voltage (HV) segmentation within the foils has been introduced. These segments are powered either by individual HV supply per segment or through an active HV distribution to manage such a large number of segments across the foil. Individual supplies apart from being costly, are highly complex to implement. Additionally, CBM will have high intensity of particles bombarding on the detector causing the change of resistive chain current feeding the GEM detector with the variation in the intensity. This leads to voltage fluctuations across the foil resulting in the gain variation with the particle intensity. Hence, a low cost active HV distribution is designed to take care of the above discussed issues

  16. The TOTEM GEM Telescope (T2) at the LHC

    International Nuclear Information System (INIS)

    Quinto, M.; Berretti, M.; David, E.; Garcia, F.; Greco, V.; Heino, J.; Hilden, T.; Kurvinen, K.; Lami, S.; Latino, G.; Lauhakangas, R.; Oliveri, E.; Ropelewski, L.; Scribano, A.; Turini, N.; Stenis, M. van

    2011-01-01

    The TOTEM T2 telescope will measure inelastically produced charged particles in the forward region of the LHC Interaction Point 5. Each arm of the telescope consists in a set of 20 triple-GEM (Gas Electron Multiplier) detectors with tracking and trigger capabilities. The GEM technology has been considered for the design of TOTEM very forward T2 telescopes thanks to its characteristics: large active areas, good position and timing resolution, excellent rate capability and radiation hardness. Each of the four T2 half arms has been fully assembled and equipped with electronics at CERN and systematically tested in the SPS beam line H8 in 2008/09. After some optimization, the operation of the GEM chambers was fully satisfactory and the T2 telescopes were installed and commissioned in their final positions at the LHC interaction point. During the first LHC run (December 2009) the T2 telescopes have collected data, at 900 GeV and 2.36 TeV. We will present here the performances of the detector and the preliminary results obtained using the data collected.

  17. The TOTEM GEM Telescope (T2) at the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Quinto, M. [INFN Sezione di Bari, Via E.Orabona n 4, 70126 Bari (Italy); Berretti, M. [University of Siena, Physics Department, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo B. Pontecorvo, 3. I-56127. Pisa (Italy); David, E. [CERN, PH Department, 1211 Geneva 23, Geneva (Switzerland); Garcia, F. [University of Helsinki, Institute of Physics and Department of Physical Sciences, Helsinki (Finland); Greco, V. [University of Siena, Physics Department, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo B. Pontecorvo, 3. I-56127. Pisa (Italy); Heino, J.; Hilden, T.; Kurvinen, K. [University of Helsinki, Institute of Physics and Department of Physical Sciences, Helsinki (Finland); Lami, S. [INFN Sezione di Pisa, Largo B. Pontecorvo, 3. I-56127. Pisa (Italy); Latino, G. [University of Siena, Physics Department, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo B. Pontecorvo, 3. I-56127. Pisa (Italy); Lauhakangas, R. [University of Helsinki, Institute of Physics and Department of Physical Sciences, Helsinki (Finland); Oliveri, E. [University of Siena, Physics Department, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo B. Pontecorvo, 3. I-56127. Pisa (Italy); Ropelewski, L. [CERN, PH Department, 1211 Geneva 23, Geneva (Switzerland); Scribano, A.; Turini, N. [University of Siena, Physics Department, Via Roma 56, I-53100 Siena (Italy); INFN Sezione di Pisa, Largo B. Pontecorvo, 3. I-56127. Pisa (Italy); Stenis, M. van [CERN, PH Department, 1211 Geneva 23, Geneva (Switzerland)

    2011-06-15

    The TOTEM T2 telescope will measure inelastically produced charged particles in the forward region of the LHC Interaction Point 5. Each arm of the telescope consists in a set of 20 triple-GEM (Gas Electron Multiplier) detectors with tracking and trigger capabilities. The GEM technology has been considered for the design of TOTEM very forward T2 telescopes thanks to its characteristics: large active areas, good position and timing resolution, excellent rate capability and radiation hardness. Each of the four T2 half arms has been fully assembled and equipped with electronics at CERN and systematically tested in the SPS beam line H8 in 2008/09. After some optimization, the operation of the GEM chambers was fully satisfactory and the T2 telescopes were installed and commissioned in their final positions at the LHC interaction point. During the first LHC run (December 2009) the T2 telescopes have collected data, at 900 GeV and 2.36 TeV. We will present here the performances of the detector and the preliminary results obtained using the data collected.

  18. Study of relevant parameters of GEM-based detectors

    CERN Document Server

    Croci, Gabriele; Sauli, Fabio; Ragazzi, S

    2007-01-01

    The Gas Electron Multiplier consist of a thin Kapton insulating (50 $\\mu$m) foil copper-clad on both sides and perforated by a high density, regular matrix of holes (around 100 per square millimeter). Typically the distance between holes (pitch) is 140 $\\mu$m and diameters of about 70 $\\mu$m. The mesh is realised by conventional photolitographic methods as used for the fabrication of multi-layer board. Upon application of a potential difference between the GEM electrodes, a high dipole field develops in the holes focusing the field lines between the drift electrode and the readout element. Electron drift along the channel and the charge is amplified by a factor that depends on the field density and the length of the channel. Owing to their excellent position resolution and rate capability GEM-based detector are very suitable to be used in different applications: from the high energy physics to the medical field. The GEM temporal and rate gain stability was studied and it was discovered that the gain variation...

  19. Analysis of GEM properties and development of a GEM support structure for the ILD time projection chamber

    Energy Technology Data Exchange (ETDEWEB)

    Hallermann, Lea

    2010-04-15

    In the concept of the International Large Detector (ILD), developed for the International Linear Collider (ILC) a Time Projection Chamber (TPC) is envisaged as main tracking detector. Such gaseous detectors have to be equipped with amplification devices in order to enlarge the amount of charge, which is set free by ionization caused by traversing charged particles. Micro Pattern Gas Detectors (MPGDs) will be used in the ILD TPC as amplification stage. In this thesis, Gas Electron Multipliers (GEMs) - one specific MPGD species - are analyzed concerning various properties. Effective gains and energy resolutions are compared for GEM foils produced by different manufacturers. A good understanding of these observables is obtained by interpretation of the results with the help of geometrical parameters. Height profile measurements of GEM foils have been performed for the first time and the impact of non perfect flat GEMs is analyzed, especially on dE/dx determination and drift field quality. The results emphasize the need of a flat installation of GEMs in TPCs. As a consequence, a new mounting device has been developed to ensure flatness and to provide a method to cover large readout areas, as in the ILD TPC, by introducing the least possible amount of dead material into the detector. The developed structure has been tested in a TPC protoype, taking cosmic muon data. The influence of the mounting on track reconstruction, single point resolution, tracking efficiency and dE/dx measurements is quantified. The developed mounting is applicable in a large scale TPC, if some design considerations are taken into account. (orig.)

  20. Analysis of GEM properties and development of a GEM support structure for the ILD time projection chamber

    International Nuclear Information System (INIS)

    Hallermann, Lea

    2010-04-01

    In the concept of the International Large Detector (ILD), developed for the International Linear Collider (ILC) a Time Projection Chamber (TPC) is envisaged as main tracking detector. Such gaseous detectors have to be equipped with amplification devices in order to enlarge the amount of charge, which is set free by ionization caused by traversing charged particles. Micro Pattern Gas Detectors (MPGDs) will be used in the ILD TPC as amplification stage. In this thesis, Gas Electron Multipliers (GEMs) - one specific MPGD species - are analyzed concerning various properties. Effective gains and energy resolutions are compared for GEM foils produced by different manufacturers. A good understanding of these observables is obtained by interpretation of the results with the help of geometrical parameters. Height profile measurements of GEM foils have been performed for the first time and the impact of non perfect flat GEMs is analyzed, especially on dE/dx determination and drift field quality. The results emphasize the need of a flat installation of GEMs in TPCs. As a consequence, a new mounting device has been developed to ensure flatness and to provide a method to cover large readout areas, as in the ILD TPC, by introducing the least possible amount of dead material into the detector. The developed structure has been tested in a TPC protoype, taking cosmic muon data. The influence of the mounting on track reconstruction, single point resolution, tracking efficiency and dE/dx measurements is quantified. The developed mounting is applicable in a large scale TPC, if some design considerations are taken into account. (orig.)

  1. Graphics gems

    CERN Document Server

    Heckbert, Paul S

    1994-01-01

    Graphics Gems IV contains practical techniques for 2D and 3D modeling, animation, rendering, and image processing. The book presents articles on polygons and polyhedral; a mix of formulas, optimized algorithms, and tutorial information on the geometry of 2D, 3D, and n-D space; transformations; and parametric curves and surfaces. The text also includes articles on ray tracing; shading 3D models; and frame buffer techniques. Articles on image processing; algorithms for graphical layout; basic interpolation methods; and subroutine libraries for vector and matrix algebra are also demonstrated. Com

  2. Photoionisation detection of single 87Rb-atoms using channel electron multipliers

    International Nuclear Information System (INIS)

    Henkel, Florian Alexander

    2011-01-01

    Fast and efficient detection of single atoms is a universal requirement concerning modern experiments in atom physics, quantum optics, and precision spectroscopy. In particular for future quantum information and quantum communication technologies, the efficient readout of qubit states encoded in single atoms or ions is an elementary prerequisite. The rapid development in the field of quantum optics and atom optics in the recent years has enabled to prepare individual atoms as quantum memories or arrays of single atoms as qubit registers. With such systems, the implementation of quantum computation or quantum communication protocols seems feasible. This thesis describes a novel detection scheme which enables fast and efficient state analysis of single neutral atoms. The detection scheme is based on photoionisation and consists of two parts: the hyperfine-state selective photoionisation of single atoms and the registration of the generated photoion-electron pairs via two channel electron multipliers (CEMs). In this work, both parts were investigated in two separate experiments. For the first step, a photoionisation probability of p ion =0.991 within an ionisation time of t ion =386 ns is achieved for a single 87 Rb-atom in an optical dipole trap. For the second part, a compact detection system for the ionisation fragments was developed consisting of two opposing CEM detectors. Measurements show that single neutral atoms can be detected via their ionisation fragments with a detection efficiency of η atom =0.991 within a detection time of t det =415.5 ns. In a future combined setup, this will allow the state-selective readout of optically trapped, single neutral 87 Rb-atoms via photoionisation detection with an estimated detection efficiency η=0.982 and a detection time of t tot = 802 ns. Although initially developed for single 87 Rb-atoms, the concept of photoionisation detection is in principle generally applicable to any atomic or molecular species. As efficient

  3. Photoionisation detection of single {sup 87}Rb-atoms using channel electron multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Henkel, Florian Alexander

    2011-09-02

    Fast and efficient detection of single atoms is a universal requirement concerning modern experiments in atom physics, quantum optics, and precision spectroscopy. In particular for future quantum information and quantum communication technologies, the efficient readout of qubit states encoded in single atoms or ions is an elementary prerequisite. The rapid development in the field of quantum optics and atom optics in the recent years has enabled to prepare individual atoms as quantum memories or arrays of single atoms as qubit registers. With such systems, the implementation of quantum computation or quantum communication protocols seems feasible. This thesis describes a novel detection scheme which enables fast and efficient state analysis of single neutral atoms. The detection scheme is based on photoionisation and consists of two parts: the hyperfine-state selective photoionisation of single atoms and the registration of the generated photoion-electron pairs via two channel electron multipliers (CEMs). In this work, both parts were investigated in two separate experiments. For the first step, a photoionisation probability of p{sub ion}=0.991 within an ionisation time of t{sub ion}=386 ns is achieved for a single {sup 87}Rb-atom in an optical dipole trap. For the second part, a compact detection system for the ionisation fragments was developed consisting of two opposing CEM detectors. Measurements show that single neutral atoms can be detected via their ionisation fragments with a detection efficiency of {eta}{sub atom}=0.991 within a detection time of t{sub det}=415.5 ns. In a future combined setup, this will allow the state-selective readout of optically trapped, single neutral {sup 87}Rb-atoms via photoionisation detection with an estimated detection efficiency {eta}=0.982 and a detection time of t{sub tot} = 802 ns. Although initially developed for single {sup 87}Rb-atoms, the concept of photoionisation detection is in principle generally applicable to any

  4. Investigations of the long-term stability of a GEM-TPC

    Energy Technology Data Exchange (ETDEWEB)

    Fedorchuk, Oleksiy [Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany); Universitaet Hamburg, Institut fuer Experimentalphysik, Luruper Chaussee 149, 22761 Hamburg (Germany); Collaboration: LCTPC-Deutschland-Collaboration

    2016-07-01

    For the International Large Detector (ILD) at the planned International Linear Collider (ILC) a Time Projection Chamber (TPC) is foreseen as the main tracking detector. The gas amplification will be done by Micro Pattern Gaseous Detectors (MPGD). One option is to use Gas Electron Multipliers (GEM).While the applicability of GEMs for the gas amplification in a TPC readout has been shown, the focus of the current research is to improve the high voltage stability and reliability of the readout modules. This is a crucial requirement for the operation in the final ILD TPC. The main focus of the research presented in this talk is on studies of the discharge stability and operational features of large area 22 x 18 cm{sup 2} GEM foils. We present systematic studies of the stability of GEM foils under different operation conditions. These studies include measurements and calculations of the dynamic behavior of charges in the GEM foils after a trip. The results will be used to develop methods to avoid destructive discharges in the final readout module.

  5. Cross-Calibration of Secondary Electron Multiplier in Noble Gas Analysis

    Science.gov (United States)

    Santato, Alessandro; Hamilton, Doug; Deerberg, Michael; Wijbrans, Jan; Kuiper, Klaudia; Bouman, Claudia

    2015-04-01

    The latest generation of multi-collector noble gas mass spectrometers has decisively improved the precision in isotopic ratio analysis [1, 2] and helped the scientific community to address new questions [3]. Measuring numerous isotopes simultaneously has two significant advantages: firstly, any fluctuations in signal intensity have no effect on the isotope ratio and secondly, the analysis time is reduced. This particular point becomes very important in static vacuum mass spectrometry where during the analysis, the signal intensity decays and at the same time the background increases. However, when multi-collector analysis is utilized, it is necessary to pay special attention to the cross calibration of the detectors. This is a key point in order to have accurate and reproducible isotopic ratios. In isotope ratio mass spectrometry, with regard to the type of detector (i.e. Faraday or Secondary Electron Multiplier, SEM), analytical technique (TIMS, MC-ICP-MS or IRMS) and isotope system of interest, several techniques are currently applied to cross-calibrate the detectors. Specifically, the gain of the Faraday cups is generally stable and only the associated amplifier must be calibrated. For example, on the Thermo Scientific instrument control systems, the 1011 and 1012 ohm amplifiers can easily be calibrated through a fully software controlled procedure by inputting a constant electric signal to each amplifier sequentially [4]. On the other hand, the yield of the SEMs can drift up to 0.2% / hour and other techniques such as peak hopping, standard-sample bracketing and multi-dynamic measurement must be used. Peak hopping allows the detectors to be calibrated by measuring an ion beam of constant intensity across the detectors whereas standard-sample bracketing corrects the drift of the detectors through the analysis of a reference standard of a known isotopic ratio. If at least one isotopic pair of the sample is known, multi-dynamic measurement can be used; in this

  6. Studies on GEM modules for a large prototype TPC for the ILC

    International Nuclear Information System (INIS)

    Tsionou, Dimitra

    2016-12-01

    The International Linear Collider (ILC) is a future electron-positron collider with centre of mass energy of 500-1000 GeV. The International Large Detector (ILD) is one of two detector concepts at the ILC. Its high precision tracking system consists of Silicon sub-detectors and a Time Projection Chamber (TPC) equipped with micro-pattern gas detectors (MPGDs). Within the framework of the LCTPC collaboration, a Large Prototype (LP) TPC has been built as a demonstrator. This prototype has been equipped with Gas Electron Multiplier (GEM) modules and studied with electron beams of energies 1-6 GeV at the DESY test beam facility. The performance of the prototype detector and the extrapolation to the ILD TPC is presented here. In addition, ongoing optimisation studies and R and D; activities in order to prepare the next GEM module iteration are discussed.

  7. Statistics of electron multiplication in a multiplier phototube; Iterative method; Estadistica de la multiplicacion de electrones en un fotomultiplicador: Metodos iterativos

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, J F; Grau, A

    1985-07-01

    In the present paper an iterative method is applied to study the variation of dynode response in the multiplier phototube. Three different situation are considered that correspond to the following ways of electronic incidence on the first dynode: incidence of exactly one electron, incidence of exactly r electrons and incidence of an average r electrons. The responses are given for a number of steps between 1 and 5, and for values of the multiplication factor of 2.1, 2.5, 3 and 5. We study also the variance, the skewness and the excess of jurtosis for different multiplication factors. (Author) 11 refs.

  8. Self-sputtering runaway in high power impulse magnetron sputtering: The role of secondary electrons and multiply charged metal ions

    International Nuclear Information System (INIS)

    Anders, Andre

    2008-01-01

    Self-sputtering runaway in high power impulse magnetron sputtering is closely related to the appearance of multiply charged ions. This conclusion is based on the properties of potential emission of secondary electrons and energy balance considerations. The effect is especially strong for materials whose sputtering yield is marginally greater than unity. The absolute deposition rate increases ∼Q 1/2 , whereas the rate normalized to the average power decreases ∼Q -1/2 , with Q being the mean ion charge state number

  9. Evaluation of a GEM and CAT-based detector for radiation therapy beam monitoring

    International Nuclear Information System (INIS)

    Brahme, A.; Danielsson, M.; Iacobaeus, C.; Ostling, J.; Peskov, V.; Wallmark, M.

    2000-01-01

    We are developing a radiation therapy beam monitor for the Karolinska Institute. This monitor will consist of two consecutive detectors confined in one gas chamber: a 'keV-photon detector', which will allow diagnostic quality visualization of the patient, and a 'MeV-photon detector', that will measure the absolute intensity of the therapy beam and its position with respect to the patient. Both detectors are based on highly radiation resistant gas and solid photon to electron converters, combined with GEMs and a CAT as amplification structures. We have performed systematic studies of the high-rate characteristics of the GEM and the CAT, as well as tested the electron transfer through these electron multipliers and various types of converters. The tests show that the GEM and the CAT satisfy all requirements for the beam monitoring system. As a result of these studies we successfully developed and tested a full section of the beam monitor equipped with a MeV-photon converter placed between the GEM and the CAT

  10. Microstructured boron foil scintillating G-GEM detector for neutron imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Takeshi, E-mail: fujiwara-t@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan); Center for Advanced Photonics, Neutron Beam Technology Team, RIKEN, Saitama (Japan); Bautista, Unico [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo (Japan); Philippine Nuclear Research Institute-Department of Science and Technology (PNRI-DOST), Commonwealth Avenue, Diliman, Quezon City (Philippines); Mitsuya, Yuki [Nuclear Professional School, The University of Tokyo, Tokai-mura, Naka-gun, Ibaraki (Japan); Takahashi, Hiroyuki [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo (Japan); Yamada, Norifumi L. [Neutron Science Laboratory, Institute of Material Structure Science, High Energy Accelerator Research Organization (KEK) (Japan); Otake, Yoshie; Taketani, Atsushi [Center for Advanced Photonics, Neutron Beam Technology Team, RIKEN, Saitama (Japan); Uesaka, Mitsuru [Nuclear Professional School, The University of Tokyo, Tokai-mura, Naka-gun, Ibaraki (Japan); Toyokawa, Hiroyuki [Research Institute for Measurement and Analytical Instrumentation, Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan)

    2016-12-01

    In this study, a new simple neutron imaging gaseous detector was successfully developed by combining a micro-structured {sup 10}B foil, a glass gas electron multiplier (G-GEM), and a mirror–lens–charge-coupled device (CCD)–camera system. The neutron imaging system consists of a chamber filled with Ar/CF{sub 4} scintillating gas mixture. Inside this system, the G-GEM is mounted for gas multiplication. The neutron detection in this system is based on the reaction between {sup 10}B and neutrons. A micro-structured {sup 10}B is developed to overcome the issue of low detection efficiency. Secondary electrons excite Ar/CF{sub 4} gas molecules, and high-yield visible photons are emitted from those excited gas molecules during the gas electron multiplication process in the G-GEM holes. These photons are easily detected by a mirror–lens–CCD–camera system. A neutron radiograph is then simply formed. We obtain the neutron images of different materials with a compact accelerator-driven neutron source. We confirm that the new scintillating G-GEM-based neutron imager works properly with low gamma ray sensitivity and exhibits a good performance as a new simple digital neutron imaging device.

  11. Detection and Imaging of High-Z Materials with a Muon Tomography Station Using GEM Detectors

    CERN Document Server

    Gnanvo, K; Bittner, W; Costa, F; Grasso, L; Hohlmann, M; Locke, J B; Martoiu, S; Muller, H; Staib, M; Tarazona, A; Toledo, J

    2010-01-01

    Muon tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons is a promising technique for detecting and imaging heavily shielded high-Z nuclear materials such as enriched uranium. This technique could complement standard radiation detection portals currently deployed at international borders and ports, which are not very sensitive to heavily shielded nuclear materials. We image small targets in 3D using $2\\times 2 \\times 2$ mm^3 voxels with a minimal muon tomography station prototype that tracks muons with Gas Electron Multiplier (GEM) detectors read out in 2D with x-y microstrips of 400 micron pitch. With preliminary electronics, the GEM detectors achieve a spatial resolution of 130 microns in both dimensions. With the next GEM-based prototype station we plan to probe an active volume of ~27 liters. We present first results on reading out all 1536 microstrips of a $30 \\times 30$ cm^2 GEM detector for the next muon tomography prototype with final frontend electronics and DAQ...

  12. A GEM of an SSC detector

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    The SSC Laboratory has decided to support the GEM (Gammas, Electrons, and Muons) detector collaboration in the next stage of its work, development of a Technical Design Report. Initial ideas for GEM as the second major SSC detector were aired last year

  13. Operation of a GEM-TPC with pixel readout

    CERN Document Server

    Brezina, C; Kaminski, J; Killenberg, M; Krautscheid, T

    2012-01-01

    A prototype time projection chamber with 26 cm drift length was operated with a short-spaced triple gas electron multiplier (GEM) stack in a setup triggering on cosmic muon tracks. A small part of the anode plane is read out with a CMOS pixel application-specified integrated circuit (ASIC) named Timepix, which provides ultimate readout granularity. Pixel clusters of charge depositions corresponding to single primary electrons are observed and analyzed to reconstruct charged particle tracks. A dataset of several weeks of cosmic ray data is analyzed. The number of clusters per track length is well described by simulation. The obtained single point resolution approaches 50 m at short drift distances and is well reproduced by a simple model of single-electron diffusion.

  14. Studies on GEM modules for a Large Prototype TPC for the ILC

    Energy Technology Data Exchange (ETDEWEB)

    Tsionou, Dimitra, E-mail: dimitra.tsionou@desy.de

    2017-02-11

    The International Linear Collider (ILC) is a future electron–positron collider with centre of mass energy of 500–1000 GeV. The International Large Detector (ILD) is one of two detector concepts at the ILC. Its high precision tracking system consists of Silicon sub-detectors and a Time Projection Chamber (TPC) equipped with micro-pattern gas detectors (MPGDs). Within the framework of the LCTPC collaboration, a Large Prototype (LP) TPC has been built as a demonstrator. This prototype has been equipped with Gas Electron Multiplier (GEM) modules and studied with electron beams of energies 1–6 GeV at the DESY test beam facility. The performance of the prototype detector and the extrapolation to the ILD TPC is presented here. In addition, ongoing optimisation studies and R&D activities in order to prepare the next GEM module iteration are discussed.

  15. BoNus: Development and use of a radial TPC using cylindrical GEMs

    International Nuclear Information System (INIS)

    Fenker, H.; Baillie, N.; Bradshaw, P.; Bueltmann, S.; Burkert, V.; Christy, M.; Dodge, G.; Dutta, D.; Ent, R.; Evans, J.; Fersch, R.; Giovanetti, K.; Griffioen, K.; Ispiryan, M.; Jayalath, C.; Kalantarians, N.; Keppel, C.; Kuhn, S.; Niculescu, G.; Niculescu, I.

    2008-01-01

    A specialized system of target and detector was developed at Jefferson Lab to provide new access to information about neutron structure from electron-neutron interactions. It allows identification and measurement of spectator protons produced in e - d→e - p s X scattering events. The detector is a radial time-projection chamber optimized for the acceptance of low-momentum protons. Gas gain is provided by three cascaded curved Gas Electron Multipliers (GEMs), the first application of GEMs in any configuration other than flat. This article provides details about the development and construction of the detector, its performance, and the analysis of the data from the successful running of its first physics experiment

  16. Studies on GEM modules for a Large Prototype TPC for the ILC

    International Nuclear Information System (INIS)

    Tsionou, Dimitra

    2017-01-01

    The International Linear Collider (ILC) is a future electron–positron collider with centre of mass energy of 500–1000 GeV. The International Large Detector (ILD) is one of two detector concepts at the ILC. Its high precision tracking system consists of Silicon sub-detectors and a Time Projection Chamber (TPC) equipped with micro-pattern gas detectors (MPGDs). Within the framework of the LCTPC collaboration, a Large Prototype (LP) TPC has been built as a demonstrator. This prototype has been equipped with Gas Electron Multiplier (GEM) modules and studied with electron beams of energies 1–6 GeV at the DESY test beam facility. The performance of the prototype detector and the extrapolation to the ILD TPC is presented here. In addition, ongoing optimisation studies and R&D activities in order to prepare the next GEM module iteration are discussed.

  17. Multiply ionization of diethyl ether clusters by 532 nm nanosecond laser: The influence of laser intensity and the electron energy distribution

    International Nuclear Information System (INIS)

    Zhang Nazhen; Wang Weiguo; Zhao Wuduo; Han Fenglei; Li Haiyang

    2010-01-01

    Graphical abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated experimentally and theoretically using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. - Abstract: The formation mechanism for multiply charged ions (C q+ and O q+ (q = 2-4)) were investigated using a dual polarity time-of-flight mass spectrometer when diethyl ether clusters interacted with nanosecond laser pulse. The signal intensity of multiply charged ions and electron energy was measured experimentally. It was shown that the intensity of multiply charged ions increased about 50 times when laser intensity increased from 7.6 x 10 9 to 7.0 x 10 10 W/cm 2 , then saturated as laser intensity increased further. It is interesting that the evolution of the mean value of electron energy was same to that of multiply charged ions. The theoretical calculation showed the ionization potential of atomic ions could be significantly decreased due to the effect of Coulomb screening especially at low laser intensity. It indicated that the electron ionization combined with Coulomb screening effect could explain the production of multiply charged ions in nanosecond laser field.

  18. Test and improvement of readout system based on APV25 chip for GEM detector

    International Nuclear Information System (INIS)

    Hu Shouyang; Jian Siyu; Zhou Jing; Shan Chao; Li Xinglong; Li Xia; Li Xiaomei; Zhou Yi

    2014-01-01

    Gas electron multiplier (GEM) is the most promising position sensitive gas detector. The new generation of readout electronics system includes APV25 front-end card, multi-purpose digitizer (MPD), VME controller and Linux-based acquisition software DAQ. The construction and preliminary test of this readout system were finished, and the ideal data with the system working frequency of 40 MHz and 20 MHz were obtained. The long time running test shows that the system has a very good time-stable ability. Through optimizing the software configuration and improving hardware quality, the noise level was reduced, and the signal noise ratio was improved. (authors)

  19. FPGA-based GEM detector signal acquisition for SXR spectroscopy system

    Science.gov (United States)

    Wojenski, A.; Pozniak, K. T.; Kasprowicz, G.; Kolasinski, P.; Krawczyk, R.; Zabolotny, W.; Chernyshova, M.; Czarski, T.; Malinowski, K.

    2016-11-01

    The presented work is related to the Gas Electron Multiplier (GEM) detector soft X-ray spectroscopy system for tokamak applications. The used GEM detector has one-dimensional, 128 channel readout structure. The channels are connected to the radiation-hard electronics with configurable analog stage and fast ADCs, supporting speeds of 125 MSPS for each channel. The digitalized data is sent directly to the FPGAs using fast serial links. The preprocessing algorithms are implemented in the FPGAs, with the data buffering made in the on-board 2Gb DDR3 memory chips. After the algorithmic stage, the data is sent to the Intel Xeon-based PC for further postprocessing using PCI-Express link Gen 2. For connection of multiple FPGAs, PCI-Express switch 8-to-1 was designed. The whole system can support up to 2048 analog channels. The scope of the work is an FPGA-based implementation of the recorder of the raw signal from GEM detector. Since the system will work in a very challenging environment (neutron radiation, intense electro-magnetic fields), the registered signals from the GEM detector can be corrupted. In the case of the very intense hot plasma radiation (e.g. laser generated plasma), the registered signals can overlap. Therefore, it is valuable to register the raw signals from the GEM detector with high number of events during soft X-ray radiation. The signal analysis will have the direct impact on the implementation of photon energy computation algorithms. As the result, the system will produce energy spectra and topological distribution of soft X-ray radiation. The advanced software was developed in order to perform complex system startup and monitoring of hardware units. Using the array of two one-dimensional GEM detectors it will be possible to perform tomographic reconstruction of plasma impurities radiation in the SXR region.

  20. Application of CMOS charge-sensitive preamplifier in triple-GEM detector

    International Nuclear Information System (INIS)

    Lai Yongfang; Li Jin; Chinese Academy of Sciences, Beijing; Deng Zhi; Li Yulan; Liu Yinong; Li Yuanjing

    2006-01-01

    Among the various micro-pattern gas detectors (MPGD) that are available, the gas electron multiplier (GEM) detector is an attractive gas detector that has been used in particle physics experiments. However the GEM detector usually needs thousands of preamplifier units for its large number of micro-pattern readout strips or pads, which leads to considerable difficulties and complexities for front end electronics (FEE). Nowadays, by making use of complementary metal-oxide semiconductor (CMOS)-based application specific integrated circuit (ASIC), it is feasible to integrate hundreds of preamplifier units and other signal process circuits in a small-sized chip, which can be bound to the readout strips or pads of a micro-pattern particle detector (MPPD). Therefore, CMOS ASIC may provide an ideal solution to the readout problem of MPPD. In this article, a triple GEM detector is constructed and one of its readout strips is connected to a CMOS charge-sensitive preamplifier chip. The chip was exposed to an 55 Fe source of 5.9 kev X-ray, and the amplitude spectrum of the chip was tested, and it was found that the energy resolution was approximately 27%, which indicates that the chip can be used in triple GEM detectors. (authors)

  1. Simulation of space-charge effects in an ungated GEM-based TPC

    Energy Technology Data Exchange (ETDEWEB)

    Böhmer, F.V., E-mail: felix.boehmer@tum.de; Ball, M.; Dørheim, S.; Höppner, C.; Ketzer, B.; Konorov, I.; Neubert, S.; Paul, S.; Rauch, J.; Vandenbroucke, M.

    2013-08-11

    A fundamental limit to the application of Time Projection Chambers (TPCs) in high-rate experiments is the accumulation of slowly drifting ions in the active gas volume, which compromises the homogeneity of the drift field and hence the detector resolution. Conventionally, this problem is overcome by the use of ion-gating structures. This method, however, introduces large dead times and restricts trigger rates to a few hundred per second. The ion gate can be eliminated from the setup by the use of Gas Electron Multiplier (GEM) foils for gas amplification, which intrinsically suppress the backflow of ions. This makes the continuous operation of a TPC at high rates feasible. In this work, Monte Carlo simulations of the buildup of ion space charge in a GEM-based TPC and the correction of the resulting drift distortions are discussed, based on realistic numbers for the ion backflow in a triple-GEM amplification stack. A TPC in the future P{sup ¯}ANDA experiment at FAIR serves as an example for the experimental environment. The simulations show that space charge densities up to 65 fC cm{sup −3} are reached, leading to electron drift distortions of up to 10 mm. The application of a laser calibration system to correct these distortions is investigated. Based on full simulations of the detector physics and response, we show that it is possible to correct for the drift distortions and to maintain the good momentum resolution of the GEM-TPC.

  2. Simulation of space-charge effects in an ungated GEM-based TPC

    International Nuclear Information System (INIS)

    Böhmer, F.V.; Ball, M.; Dørheim, S.; Höppner, C.; Ketzer, B.; Konorov, I.; Neubert, S.; Paul, S.; Rauch, J.; Vandenbroucke, M.

    2013-01-01

    A fundamental limit to the application of Time Projection Chambers (TPCs) in high-rate experiments is the accumulation of slowly drifting ions in the active gas volume, which compromises the homogeneity of the drift field and hence the detector resolution. Conventionally, this problem is overcome by the use of ion-gating structures. This method, however, introduces large dead times and restricts trigger rates to a few hundred per second. The ion gate can be eliminated from the setup by the use of Gas Electron Multiplier (GEM) foils for gas amplification, which intrinsically suppress the backflow of ions. This makes the continuous operation of a TPC at high rates feasible. In this work, Monte Carlo simulations of the buildup of ion space charge in a GEM-based TPC and the correction of the resulting drift distortions are discussed, based on realistic numbers for the ion backflow in a triple-GEM amplification stack. A TPC in the future P ¯ ANDA experiment at FAIR serves as an example for the experimental environment. The simulations show that space charge densities up to 65 fC cm −3 are reached, leading to electron drift distortions of up to 10 mm. The application of a laser calibration system to correct these distortions is investigated. Based on full simulations of the detector physics and response, we show that it is possible to correct for the drift distortions and to maintain the good momentum resolution of the GEM-TPC

  3. Multi-anode photon-multiplier readout electronics for the LHCb ring imaging Cherenkov detectors

    CERN Document Server

    Smale, N J

    2004-01-01

    A readout system for the Ring Imaging CHerenkov (RICH) detectors of the LHCb experiment has been developed. Two detector technologies for the measurement of Cherenkov photons are considered, the Multi-Anode Photo-Multiplier Tube (MAPMT) and the Hybrid Photon Detector (HPD), both of which meet the RICH requirements. The properties of the MAPMT are evaluated using a controlled single-photon source; a pixel-to-pixel gain variation of ~3 and a typical signal to noise of ~20 is measured. The relative tube efficiency is found to be reduced by ~26 % due to the detailed focusing structure of the MAPMT device. A radiation hard application-specific integrated circuit (ASIC) chip, the Beetle1.2MA0, has been developed to capture and store signals from a pair of MAPMTs. The Beetle1.2MA0 is built on the architecture of the Beetle family that was designed for silicon strip detectors, the difference being a modified front-end amplifier. The 128 input-channels of the Beetle1.2MA0 have a charge-sensitive pre-amplifier followed...

  4. Electron loss process and cross section of multiply charged ions by neutral atoms

    International Nuclear Information System (INIS)

    Karashima, S.; Watanabe, T.

    1985-01-01

    The significance of experimental and theoretical results on the electron loss and capture of ions in matter plays an important role in the charge equilibrium problems of fusion plasma physics and of accelerator physics. In the report, we calculate electron stripping cross section by using the binary encounter approximation (BEA). Our treatment of the electron loss process is based on BEA, in which the nucleus of B screened by the surrounding electrons collides with electrons in the ion A sup(q+). The basic approximation in EBA is that the ion interacts with only one electron or nucleus of the target atom at a time. In the calculation for Li sup(2+) + H, we have found that EBA will give approximately reliable results. (Mori, K.)

  5. The detection of hard x-rays (10-140 KeV) by channel plate electron multipliers

    International Nuclear Information System (INIS)

    Bateman, J.E.

    1976-12-01

    Results are presented indicating that hard X-rays in the energy range 10 to 50 keV can be detected with good efficiency (5 to 10%) in channel plate electron multipliers (CPEM). From 50 keV to 140 keV the detection efficiency lies in the range 1 to 2%. A simple physical model is developed which indicates that not only can good detection efficiency be obtained but that very good X-ray imaging is possible. The model predicts that with further development, a wideband, hard X-ray detector can be realised with a detection efficiency in the range 5 to 20% and spatial response better than 10 lp/mm in the energy range 10 to 140 keV. (author)

  6. Electron beam effects on the spectroscopy of multiply charged ions in plasma focus experiments

    International Nuclear Information System (INIS)

    Abdallah, J.; Clark, R.E.H.; Faenov, A.Y.; Karpinski, L.; Pikuz, S.A.; Romanova, V.M.; Sadowski, M.; Scholz, M.; Szydlowski, A.

    1999-01-01

    Argon-hydrogen mixture plasma focus experiments performed at the Warsaw Institute of Plasma Physics and Laser Microfusion show detailed space resolved spectra for Ar K-shell satellite lines up to F-like Ar and K-alpha of Ar. These transitions originating from autoionizing levels are caused by collisions of ions with the energetic electron beams which are created by the constrictions of the plasma column due to the development of magnetohydrodynamic instabilities. A collisional-radiative model was constructed using a non-Maxwellian electron energy distribution consisting of a thermal Maxwellian part plus a Gaussian part to represent the high-energy electron beam. The shapes of the observed satellite structures are consistent with the calculated spectrum for electron temperatures between 20 and 230 eV, and beam densities of about 10 -3 times the plasma electron density. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. Electron beam effects on the spectroscopy of multiply charged ions in plasma focus experiments

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, J. [UCLA Plasma Physics Laboratory, Los Angeles, CA (United States); Clark, R.E.H. [Los Alamos National Laboratory, Los Alamos, NM (United States); Faenov, A.Y. [MISDC, NPO ' VNIIFTRI' , Mendeleevo, Moscow region, 141570 (Russian Federation); Karpinski, L. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Pikuz, S.A.; Romanova, V.M. [P. N. Lebedev Physical Institute, Moscow (Russian Federation); Sadowski, M. [Soltan Institute for Nuclear Studies, Swierk (Poland); Scholz, M.; Szydlowski, A. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland)

    1999-05-01

    Argon-hydrogen mixture plasma focus experiments performed at the Warsaw Institute of Plasma Physics and Laser Microfusion show detailed space resolved spectra for Ar K-shell satellite lines up to F-like Ar and K-alpha of Ar. These transitions originating from autoionizing levels are caused by collisions of ions with the energetic electron beams which are created by the constrictions of the plasma column due to the development of magnetohydrodynamic instabilities. A collisional-radiative model wasconstructed using a non-Maxwellian electron energy distribution consisting of a thermal Maxwellian part plus a Gaussian part to represent the high-energy electron beam. The shapes of the observed satellite structures are consistent with the calculated spectrum for electron temperatures between 20 and 230 eV, and beam densities of about 10{sup -3} times the plasma electron density. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. Improving the resolution in soft X-ray emission spectrometers through photon-counting using an Electron Multiplying CCD

    International Nuclear Information System (INIS)

    Hall, D J; Soman, M; Tutt, J; Murray, N; Holland, A; Schmitt, T; Raabe, J; Strocov, V N; Schmitt, B

    2012-01-01

    In 2007, a study of back-illuminated Charge-Coupled Devices (CCDs) for soft X-ray photon detection demonstrated the improvements that could be brought over more traditional micro-channel plate detectors for X-ray spectrometers based on diffraction gratings and position sensitive detectors. Whilst the spatial resolution was reported to be improved dramatically, an intrinsic limit of approximately 25 micrometers was found due to the spreading of the charge cloud generated in the CCD across several pixels. To overcome this resolution limit, it is necessary to move away from the current integrated imaging methods and consider a photon-counting approach, recording the photon interaction locations to the sub-pixel level. To make use of photon-counting techniques it is important that the individual events are separable. To maintain the throughput of the spectrometer for high intensity lines, higher frame rates and therefore higher readout speeds are required. With CCD based systems, the increased noise at high readout speeds can limit the photon-counting performance. The Electron-Multiplying CCD shares a similar architecture with the standard CCD but incorporates a g ain register . This novel addition allows controllable gain to be applied to the signal before the read noise is introduced, therefore allowing individual events to be resolved above the noise even at much higher readout rates. In the past, the EM-CCD has only been available with imaging areas too small to be practical in soft X-ray emission spectrometers. The current drive for large area Electron-Multiplying CCDs is opening this technology to new photon-counting applications, requiring in-depth analysis of the processes and techniques involved. Early results indicate that through the introduction of photon-counting techniques the resolution in such systems can be dramatically improved.

  9. Study of long-term operation of triple-GEM detectors for the high rate environment in CMS

    CERN Document Server

    Merlin, Jeremie Alexandre

    2013-01-01

    The CMS GEM collaboration is working on the possible instrumentation of the high-eta region of the CMS Endcap with Gas Electron Multiplier (GEM) detectors, a technology capable to sustain the hostile environment that will be encountered at the high-luminosity LHC. To ensure the long-term operation of large triple-GEM detectors in the CMS experiment, we are performing a set of studies in order to measure and understand the aging effect of triple-GEM Muon chambers. The aging includes all the processes that lead to a significant degradation of the performances of the detector gain drop, non-uniformity, dark current, discharges and resolution loss. The project is focused on monitoring continuously the response of the detector when irradiated by a source of Cs 137 at CERN in the Gamma Irradiation Facility (GIF). Moreover, the new technology employed for stretching the GEM foils, so called NS2, introduces new, carefully chosen materials and components in the detectors. Outgassing tests are performed in order to va...

  10. Detector system for particle or quantum radiation with a multitude of channel secondary electron multipliers arranged in the form of a laminar matrix

    Energy Technology Data Exchange (ETDEWEB)

    Manley, B W; Burgess, H

    1979-01-11

    The detector system may be used in diagnostic X-ray or gamma radiography. It essentially consists of a great number of channel secondary electron multipliers assigned to which are two electrodes consisting of parallel electrode strips each. The strips in one electrode are some distance away from those of the other electrode and are shifted by 90/sup 0/ with respect to them. Each electrode strip has got a connection joined to a charge detection circuit. This charge detection circuit contains a logic circuit by which a reliable assessment of the surface distribution of the particles resp. quanta hitting the channel secondary electron multipliers is made possible.

  11. Implementation of the P barANDA Planar-GEM tracking detector in Monte Carlo simulations

    Science.gov (United States)

    Divani Veis, Nazila; Ehret, Andre; Firoozabadi, Mohammad M.; Karabowicz, Radoslaw; Maas, Frank; Saito, Nami; Saito, Takehiko R.; Voss, Bernd; PANDA Gem-Tracker Subgroup

    2018-02-01

    The P barANDA experiment at FAIR will be performed to investigate different aspects of hadron physics using anti-proton beams interacting with a fixed nuclear target. The experimental setup consists of a complex series of detector components covering a large solid angle. A detector with a gaseous active media equipped with gas electron multiplier (GEM) technique will be employed to measure tracks of charged particles at forward direction in order to achieve a high momentum resolution. In this work, a full setup of the GEM tracking detector has been implemented in the P barANDA Monte Carlo simulation package (PandaRoot) based on the current technical and conceptual design, and the expected performance of the P barANDA GEM-tracking detector has been investigated. Furthermore, material-budget studies in terms of the radiation length of the P barANDA GEM-tracking detector have been made in order to investigate the effect of the detector materials and its associated structures to particle measurements.

  12. Studies of characteristics of triple GEM detector for the ALICE-TPC upgrade

    International Nuclear Information System (INIS)

    Patra, Rajendra Nath; Singaraju, R.N.; Ahammed, Z.; Nayak, T.K.; Biswas, S.

    2015-01-01

    Gas Electron Multiplier (GEM) is a novel gas detector in the field of radiation detection. GEM detectors have tremendous advantages over other types gas detectors like high rate handling capability with high efficiency and very low ion back flow (IBF). These detectors are most suitable for the use in the future experiments in high-energy proton-proton and heavy-ion collisions at the Large Hadron Collider (LHC) at CERN and Facility for Antiproton and Ion Research (FAIR) at GSI. A Large Ion Collider Experiment (ALICE) at the LHC is a dedicated experiment for the study of Quark Gluon Plasma (QGP). In few years, the data taking rate for Pb-Pb collisions will increase by 100 times to 50 KHz. The ALICE Time Projection Chamber (TPC) is the main tracking detector in ALICE. It is planned that by the year 2018, GEM detectors will replace the present readout planes of TPC. The goal of the present study is to characterize the GEM detector to achieve the performance goal of the TPC

  13. Characteristics of triple GEM detector for the ALICE TPC upgrade at CERN

    International Nuclear Information System (INIS)

    Patra, Rajendra Nath; Singaraju, R.N.; Ahammed, Z.; Nayak, T.K.; Viyogi, Y.P.; Biswas, S.

    2016-01-01

    Gas Electron Multiplier (GEM) detector, introduced by F. Sauliin 1997 and has been widely improved in last two decades for applications to high energy physics experiments and imaging. GEM detectors have several advantages, like good spatial resolution (∼100 μm), high detection efficiency (>98%), high rate handling capability (∼105 Hz/mm"2 ) and reasonable time response (∼5 ns). The unique features of the GEM detector make it suitable for experiments at Large Hadron Collider (LHC) at CERN and FAIR at GSI. With the increase of beam luminosity of LHC for its next phase of running from the year 2020, the ALICE experiment is planning to take data for PbPb collisions at a rate of 50 kHz. The ALICE Time Projection Chamber (TPC) will be upgraded by GEM based read-out to fulfil this future goal. In this report, results of a thorough test in the laboratory using a newly developed online data monitoring system are discussed

  14. arXiv GEM Foil Quality Assurance For The ALICE TPC Upgrade

    CERN Document Server

    INSPIRE-00019412; Hildén, Timo

    2018-01-01

    The ALICE (A Large Ion Collider Experiment) experiment at the Large Hadron Collider (LHC) at CERN is dedicated to heavy ion physics to explore the structure of strongly interacting matter. The Time Projection Chamber (TPC) of ALICE is a tracking detector located in the central region of the experiment. It offers excellent tracking capabilities as well as particle identification. After the second long shutdown (LS2) the LHC will run at substantially higher luminosities. To be able to increase the data acquisition rate by a factor of 100, the ALICE TPC experiment has to replace the Multi-Wire Proportional Chamber (MWPC) –based readout chambers. The MWPC are operated with gating grid that limits the rate to O(kHz). The new ReadOut Chamber (ROC) design is based on Gas Electron Multiplier (GEM) technology operating in continuous mode. The current GEM productions scheme foresees the production of more than 800 GEM foils of different types. To fulfill the requirements on the performance of the GEM TPC readout, nec...

  15. Electron capture and ionization in collisions of multiply charged ions with H(2s)

    International Nuclear Information System (INIS)

    Errea, L F; Guzman, F; Illescas, Clara; Mendez, L; Pons, B; Riera, A; Suarez, J

    2007-01-01

    We present total cross sections for electron capture and ionization in collisions of B 5+ and Ne 10+ with H(2s), calculated using two methods: the semiclassical close-coupling molecular formalism and the eikonal-CTMC method. We have evaluated partial cross sections for capture into excited n-levels, required in plasma diagnostics

  16. Spatial resolution studies of a GEM-TPC

    Energy Technology Data Exchange (ETDEWEB)

    Berger, Martin [TU Muenchen, 85748 Garching (Germany); Collaboration: GEM-TPC-Collaboration

    2015-07-01

    A GEM-TPC can exploit the intrinsic suppression of back drifting ions from the amplification stage of the GEM (Gas Electron Multiplier) foils to overcome the problem of drift-field distortions in an ungated operation. To explore the possibility of such a continuously running TPC (Time Projection Chamber) a large-size detector was built. This detector, with a drift length of 728 mm and a radius of 308 mm and a total of 10254 electronic channels, was designed as an upgrade for the FOPI experiment at GSI (Darmstadt, Germany) to improve the secondary vertex resolution especially for K{sup 0}{sub S}- and Λ-reconstruction and the PID capabilities. After commissioning a large statistics of cosmic data and beam-target reactions has been collected and the obtained tracks in the TPC have been used to improve the tracking algorithms. During the track finding and fitting procedure a clustering algorithm which takes into account the track topology as well as the full 3D spatial information is employed. The the clustering algorithm, the cluster error calculation and the tracking resolution are discussed in this contribution.

  17. Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a muon tomography station based on GEM detectors

    Energy Technology Data Exchange (ETDEWEB)

    Gnanvo, Kondo, E-mail: kgnanvo@fit.edu [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Grasso, Leonard V.; Hohlmann, Marcus; Locke, Judson B.; Quintero, Amilkar [Department of Physics and Space Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States); Mitra, Debasis [Department of Computer Sciences, Florida Institute of Technology, Melbourne, FL 32901 (United States)

    2011-10-01

    Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30 cmx30 cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes ({approx}0.03 L) using GEM-based Muon Tomography.

  18. Imaging of high-Z material for nuclear contraband detection with a minimal prototype of a muon tomography station based on GEM detectors

    International Nuclear Information System (INIS)

    Gnanvo, Kondo; Grasso, Leonard V.; Hohlmann, Marcus; Locke, Judson B.; Quintero, Amilkar; Mitra, Debasis

    2011-01-01

    Muon Tomography based on the measurement of multiple scattering of atmospheric cosmic ray muons in matter is a promising technique for detecting heavily shielded high-Z radioactive materials (U, Pu) in cargo or vehicles. The technique uses the deflection of cosmic ray muons in matter to perform tomographic imaging of high-Z material inside a probed volume. A Muon Tomography Station (MTS) requires position-sensitive detectors with high spatial resolution for optimal tracking of incoming and outgoing cosmic ray muons. Micro Pattern Gaseous Detector (MPGD) technologies such as Gas Electron Multiplier (GEM) detectors are excellent candidates for this application. We have built and operated a minimal MTS prototype based on 30 cmx30 cm GEM detectors for probing targets with various Z values inside the MTS volume. We report the first successful detection and imaging of medium-Z and high-Z targets of small volumes (∼0.03 L) using GEM-based Muon Tomography.

  19. Effect of an electron beam generated in an X-pinch plasma on the structure of the K spectra of multiply charged ions

    International Nuclear Information System (INIS)

    Pikuz, S.A.; Shelkovenko, T.A.; Ramanova, V.M.; Abdallah, J. Jr.; Csanak, G.; Clark, R.E.H.; Faenov, A.Ya.; Skobelev, I.Yu.; Hammer, D.A.

    1997-01-01

    The first experimental studies of an electron beam generated in an X pinch on the XP machine (Cornell University, USA) and the BIN machine (P. N. Lebedev Physical Institute, Russian Academy of Sciences) are reported. It is shown that it is possible in an X pinch to isolate the effect of a plasma-generated electron beam on the multiply charged ion radiation. The intensities of the satellite lines corresponding to Li-, Be-, B-, and C-like ions are calculated for the Al spectrum on the basis of a collisional-radiative model with a non-Maxwellian electron distribution in the plasma. The effect of an electron beam on the multiply charged light ion radiation in an X-pinch plasma is demonstrated. Comparing our calculations with the experimental spectra, we conclude that the present model can be used to estimate the electron beam intensity

  20. Optimizing low-light microscopy with back-illuminated electron multiplying charge-coupled device: enhanced sensitivity, speed, and resolution.

    Science.gov (United States)

    Coates, Colin G; Denvir, Donal J; McHale, Noel G; Thornbury, Keith D; Hollywood, Mark A

    2004-01-01

    The back-illuminated electron multiplying charge-coupled device (EMCCD) camera is having a profound influence on the field of low-light dynamic cellular microscopy, combining highest possible photon collection efficiency with the ability to virtually eliminate the readout noise detection limit. We report here the use of this camera, in 512 x 512 frame-transfer chip format at 10-MHz pixel readout speed, in optimizing a demanding ultra-low-light intracellular calcium flux microscopy setup. The arrangement employed includes a spinning confocal Nipkow disk, which, while facilitating the need to both generate images at very rapid frame rates and minimize background photons, yields very weak signals. The challenge for the camera lies not just in detecting as many of these scarce photons as possible, but also in operating at a frame rate that meets the temporal resolution requirements of many low-light microscopy approaches, a particular demand of smooth muscle calcium flux microscopy. Results presented illustrate both the significant sensitivity improvement offered by this technology over the previous standard in ultra-low-light CCD detection, the GenIII+intensified charge-coupled device (ICCD), and also portray the advanced temporal and spatial resolution capabilities of the EMCCD. Copyright 2004 Society of Photo-Optical Instrumentation Engineers.

  1. Channel electron multiplier operated on a sounding rocket without a cryogenic vacuum pump from 120 to 80 km altitude

    Science.gov (United States)

    Dickson, Shannon; Gausa, Michael; Robertson, Scott; Sternovsky, Zoltan

    2013-04-01

    We demonstrate that a channel electron multiplier (CEM) can be operated on a sounding rocket in the pulse-counting mode from 120 km to 80 km altitude without the cryogenic evacuation used in the past. Evacuation of the CEM is provided only by aerodynamic flow around the rocket. This demonstration is motivated by the need for additional flights of mass spectrometers to clarify the fate of metallic compounds and ions ablated from micrometeorites and their possible role in the nucleation of noctilucent clouds. The CEMs were flown as guest instruments on two sounding rockets to the mesosphere. Modeling of the aerodynamic flow around the payload with Direct Simulation Monte-Carlo (DSMC) code showed that the pressure is reduced below ambient in the void behind (relative to the direction of motion) an aft-facing surface. An enclosure containing the CEM was placed forward of an aft-facing deck and a valve was opened during flight to expose the CEM to the aerodynamically evacuated region behind it. The CEM operated successfully from apogee down to ∼80 km. A Pirani gauge confirmed pressures reduced to as low as 20% of ambient with the extent of reduction dependent upon altitude and velocity. Additional DSMC simulations indicate that there are alternate payload designs with improved aerodynamic pumping for forward mounted instruments such as mass spectrometers.

  2. Mass spectrometric determination of magnesium isotopic ratios and its corrections for electron multiplier discrimination and mass fractionation

    International Nuclear Information System (INIS)

    Deng Zhongguo

    1989-01-01

    The mass spectrometric determination of magnesium isotopic ratios by the use of uranyl nitrate added to magnesium samples to act as a binding agent is reported. Prebaking empty filaments and preheating filaments with deposited magnesium samples on its surface in a vacuum are employed to reduce the Na signal from the thenium-ribbon. Methods for correcting magnesium isotopic ratios for electron multiplier discrimination and mass fractionation are described in detail. The results of the determination of natural magnesium isotopic ratios are 25 Mg/ 24 Mg = 0.12660 (1±0.01%) and 26 Mg/ 24 Mg = 0.13938 (1±0.10%). The magnesium isotopic ratios of rich - 26 Mg-2 sample and rich- 25 Mg-1 sample are 24 Mg/ 26 Mg = 0.003463 (1±0.2%), 25 Mg/ 26 Mg = 0.001656 (±0.2%) and 24 Mg/ 25 Mg = 0.006716 (1±0.2%), 26 Mg/ 25 Mg = 0.007264 (1±0.2%) respectively

  3. Modulated electron-multiplied fluorescence lifetime imaging microscope: all-solid-state camera for fluorescence lifetime imaging.

    Science.gov (United States)

    Zhao, Qiaole; Schelen, Ben; Schouten, Raymond; van den Oever, Rein; Leenen, René; van Kuijk, Harry; Peters, Inge; Polderdijk, Frank; Bosiers, Jan; Raspe, Marcel; Jalink, Kees; Geert Sander de Jong, Jan; van Geest, Bert; Stoop, Karel; Young, Ian Ted

    2012-12-01

    We have built an all-solid-state camera that is directly modulated at the pixel level for frequency-domain fluorescence lifetime imaging microscopy (FLIM) measurements. This novel camera eliminates the need for an image intensifier through the use of an application-specific charge coupled device design in a frequency-domain FLIM system. The first stage of evaluation for the camera has been carried out. Camera characteristics such as noise distribution, dark current influence, camera gain, sampling density, sensitivity, linearity of photometric response, and optical transfer function have been studied through experiments. We are able to do lifetime measurement using our modulated, electron-multiplied fluorescence lifetime imaging microscope (MEM-FLIM) camera for various objects, e.g., fluorescein solution, fixed green fluorescent protein (GFP) cells, and GFP-actin stained live cells. A detailed comparison of a conventional microchannel plate (MCP)-based FLIM system and the MEM-FLIM system is presented. The MEM-FLIM camera shows higher resolution and a better image quality. The MEM-FLIM camera provides a new opportunity for performing frequency-domain FLIM.

  4. A micro-TCA based data acquisition system for the Triple-GEM detectors for the upgrade of the CMS forward muon spectrometer

    Science.gov (United States)

    Lenzi, T.

    2017-01-01

    The Gas Electron Multiplier (GEM) upgrade project aims at improving the performance of the muon spectrometer of the Compact Muon Solenoid (CMS) experiment which will suffer from the increase in luminosity of the Large Hadron Collider (LHC). The GEM collaboration proposes to instrument the first muon station with Triple-GEM detectors, a technology which has proven to be resistant to high fluxes of particles. The architecture of the readout system is based on the use of the microTCA standard hosting FPGA-based Advanced Mezzanine Card (AMC) and of the Versatile Link with the GBT chipset to link the on-detector electronics to the micro-TCA boards. For the front-end electronics a new ASIC, called VFAT3, is being developed. On the detector, a Xilinx Virtex-6 FPGA mezzanine board, called the OptoHybrid, has to collect the data from 24 VFAT3s and to transmit the data optically to the off-detector micro-TCA electronics, as well as to transmit the trigger data at 40 MHz to the CMS Cathode Strip Chamber (CSC) trigger. The microTCA electronics provides the interfaces from the detector (and front-end electronics) to the CMS DAQ, TTC (Timing, Trigger and Control) and Trigger systems. In this paper, we will describe the DAQ system of the Triple-GEM project and provide results from the latest test beam campaigns done at CERN.

  5. Development of the DAQ System of Triple-GEM Detectors for the CMS Muon Spectrometer Upgrade at LHC

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00387583

    The Gas Electron Multiplier (GEM) upgrade project aims at improving the performance of the muon spectrometer of the Compact Muon Solenoid (CMS) experiment which will suffer from the increase in luminosity of the Large Hadron Collider (LHC). After a long technical stop in 2019-2020, the LHC will restart and run at a luminosity of 2 × 1034 cm−2 s−1, twice its nominal value. This will in turn increase the rate of particles to which detectors in CMS will be exposed and affect their performance. The muon spectrometer in particular will suffer from a degraded detection efficiency due to the lack of redundancy in its most forward region. To solve this issue, the GEM collaboration proposes to instrument the first muon station with Triple-GEM detectors, a technology which has proven to be resistant to high fluxes of particles. Within the GEM collaboration, the Data Acquisition (DAQ) subgroup is in charge of the development of the electronics and software of the DAQ system of the detectors. This thesis presents th...

  6. Not Your Ordinary GEM

    Science.gov (United States)

    2001-01-01

    Through Small Business Innovation Research (SBIR) funding from NASA's Stennis Space Center, Geophex devised a new design for broadband electromagnetic sensors. Geophex developed a patented sensing technology, capable not only of coastal monitoring, but also a variety of other functions, including environmental pollution characterization, groundwater contamination detection, archaeological study, and mineral detection. The new technology is offered in several of the company's products the GEM-2, GEM-2A, and the GEM-3. The Geophex products consist of two primary electromagnetic coils, which are stimulated by alternating currents that generate a magnetic field in the object targeted for investigation. GEM-2 is a handheld, lightweight, programmable, digital device. GEM-2A is an airborne version of the sensor. Suspended from a helicopter, the GEM-2A is used to search for mineral deposits and to survey large tracts of land. The GEM-3 is capable of detecting buried landmines and other active munitions. GEM-3 identifies landmines by their brand names. Because each landmine has its own unique electromagnetic response to the broad frequency band emitted by the GEM-3, bomb identification and disposal strategies are made easier.

  7. Resolution studies of a GEM-based TPC

    International Nuclear Information System (INIS)

    Killenberg, M.

    2006-01-01

    Currently there are four different concept studies trying to optimise the detector for the requirements at the ILC. In three of these detector concepts a time projection chamber (TPC) is foreseen as the main tracking device. To achieve the intended spatial resolution of 100 μm, micro pattern gas detectors (MPGD) are considered for gas amplification. The two different MPGDs discussed for the ILC TPC are Micro-Mesh Gaseous Detectors (Micromegas) and Gas Electron Multiplier foils (GEMs). The current thesis shows resolution studies with a TPC prototype equipped with a triple GEM readout structure. A hodoscope made up of silicon strip sensors gives a precision reference track, allowing an unbiased measurement of the spatial resolution. High statistics measurements have been conducted at the DESY test beam facility, which provides positrons with a tunable energy between 1 GeV and 6 GeV. Using the independent measurement of the hodoscope allows systematic studies of the homogeneity of the TPC's electric field. The fluctuations of the field in the chamber's central region were found to be ΔE/E=8.10 -3 . Field distortions have been determined and corrected, reducing the remaining deviations to a level well below the spatial resolution of the TPC. One important task is to reduce the number of ions drifting back into the sensitive volume. Special GEM settings with minimised ion backdrift have been examined with respect to their influence on the spatial resolution and it was found that the spatial resolution is not degraded using these special settings. The TPC prototype has been operated in a 4 T magnetic field, provided by a superconducting solenoid located at DESY Hamburg. Again the spatial resolution measured with the ion backdrift optimised settings is compared to that achieved with nonoptimised settings. In both cases the measured resolution is approximately 130 μm. (orig.)

  8. Resolution studies of a GEM-based TPC

    Energy Technology Data Exchange (ETDEWEB)

    Killenberg, M.

    2006-12-15

    Currently there are four different concept studies trying to optimise the detector for the requirements at the ILC. In three of these detector concepts a time projection chamber (TPC) is foreseen as the main tracking device. To achieve the intended spatial resolution of 100 {mu}m, micro pattern gas detectors (MPGD) are considered for gas amplification. The two different MPGDs discussed for the ILC TPC are Micro-Mesh Gaseous Detectors (Micromegas) and Gas Electron Multiplier foils (GEMs). The current thesis shows resolution studies with a TPC prototype equipped with a triple GEM readout structure. A hodoscope made up of silicon strip sensors gives a precision reference track, allowing an unbiased measurement of the spatial resolution. High statistics measurements have been conducted at the DESY test beam facility, which provides positrons with a tunable energy between 1 GeV and 6 GeV. Using the independent measurement of the hodoscope allows systematic studies of the homogeneity of the TPC's electric field. The fluctuations of the field in the chamber's central region were found to be {delta}E/E=8.10{sup -3}. Field distortions have been determined and corrected, reducing the remaining deviations to a level well below the spatial resolution of the TPC. One important task is to reduce the number of ions drifting back into the sensitive volume. Special GEM settings with minimised ion backdrift have been examined with respect to their influence on the spatial resolution and it was found that the spatial resolution is not degraded using these special settings. The TPC prototype has been operated in a 4 T magnetic field, provided by a superconducting solenoid located at DESY Hamburg. Again the spatial resolution measured with the ion backdrift optimised settings is compared to that achieved with nonoptimised settings. In both cases the measured resolution is approximately 130 {mu}m. (orig.)

  9. A TPC-like readout method for high precision muon-tracking using GEM-detectors

    Energy Technology Data Exchange (ETDEWEB)

    Flierl, Bernhard; Biebel, Otmar; Bortfeldt, Jonathan; Hertenberger, Ralf; Klitzner, Felix; Loesel, Philipp; Mueller, Ralph [Ludwig-Maximilians-Universitaet Muenchen (Germany); Zibell, Andre [Julius-Maximilians-Universitaet Wuerzburg (Germany)

    2016-07-01

    Gaseous electron multiplier (GEM) detectors are well suited for tracking of charged particles. Three dimensional tracking in a single layer can be achieved by application of a time-projection-chamber like readout mode (μTPC), if the drift time of the electrons is measured and the position dependence of the arrival time is used to calculate the inclination angle of the track. To optimize the tracking capabilities for ion tracks drift gas mixtures with low drift velocity have been investigated by measuring tracks of cosmic muons in a compact setup of four GEM-detectors of 100 x 100 x 6 mm{sup 3} active volume each and an angular acceptance of -25 to 25 . The setup consists of three detectors with two-dimensional strip readout layers of 0.4 mm pitch and one detector with a single strip readout layer of 0.25 mm pitch. All strips are readout by APV25 frontend boards and the amplification stage in the detectors consists of three GEM-foils. Tracks are reconstructed by the μTPC-method in one of the detectors and are then compared to the prediction from the other three detectors defined by the center of charge in every detector. We report our study of Argon and Helium based noble gas mixtures with carbon-dioxide as quencher.

  10. Gas amplification properties of GEM foils

    International Nuclear Information System (INIS)

    Beck, Jeannine

    2009-01-01

    In the framework of the detector concept International Linear Detector for the future accelerator project International Linear Collider, in which electrons and positrons at c. m. energies of 500 GeV are brought to collision, a time projection chamber shall be applied as central track detector. By the application of such a chamber as track detector a three-dimensional reconstruction of the track points is possible. If a particle passes the gas volume within the chamber it ionizises single gas atoms and the arising electrons move after the amplification in the GEM arrangement to the anode, so that a two-dimensional projection of the particle track is possible. The third dimension is calculated from the drift time of the electrons. The advances of this readout system consist therein that a better position resolution than by a multiwire proportional chamber is reached and the back-drifting ions can be strongly suppressed. Aim of this thesis are studies for a GEM module, which shall be used in a large TPC prototype. Concerning different requirements it is valid to compare different GEMs in order to can meet an optimal choice. In a small prototype present at DESY measurements for the acquisition of GEM-describing parameters were performed. The taking into operation of the test TPC was part of this thesis. Tracks were generated by a radioactive source, by means of which the gas amplification was determined. With the measurement arrangement gas-amplifier foils of different kind were compared in view of their amplification properties and their energy resolution power and systematically studied. Five different GEM performances were studied in the test TPC. These foils differ in their geometrical classification parameters, the fabrication process, or the materials. The GEMs produced at CERN possess in comparison with GEMs of the Japanese firm SciEnergy and a GEM of the US-American firm Tech-Etch the best amplification and resolution properties. Furthermore a new GEM framing

  11. Multiplying Money

    Directory of Open Access Journals (Sweden)

    Garry Jacobs

    2013-05-01

    Full Text Available This article is not a comprehensive factual history of money as an economic instrument. It aims rather to present an essential psychological history of the power of money as a social organization or social technology. It explores the catalytic role of money in the development of society and its ever-increasing capacity for accomplishment in both economic and non-economic fields. This perspective focuses attention on the unutilized potential for harnessing the social power of money for promoting full employment, global development and human welfare. The title ‘multiplying money’ is intended to convey the idea that this untapped potential is exponential in nature. In order to recognize it, some fundamental misconceptions about the nature of money, how it is created and on what it is based need to be examined. This is the second article in a series.

  12. Limitation of secondary electron multiplier non-linearity on accurate U-Th isotopic determination by MC-ICP-MS

    Science.gov (United States)

    Shen, C.; Wu, C.; Gallet, S.; Cheng, H.; Edwards, R.; Hsieh, Y.; Lin, K.

    2008-12-01

    Contemporary multicollector-inductively coupled plasma mass spectrometry (MC-ICP-MS) with discrete dynode secondary electron multipliers (SEMs) can offer U-Th isotopic determinations with subpermil-permil- level precision in femtogram quantities. However, accurate isotopic measurement requires fully understanding SEM mass and intensity biases. In additional to dead-time effect, Richter et al (2001, Int. J. Mass Spectrom., 206, 105-127) reported a nonlinearity on SEMs produced by ETP and MasCom for count rates > 20 thousand counts per second (cps). We evaluated the possible biases for ion beams of 500- 1,600,000 cps on a latest MasCom SEM, SEV TE-Z/17, with more effective ion optical acceptance area (>50%) and better peak shape than previous models, used in a MC-ICP-MS, Thermo Fisher NEPTUNE. With the retarding potential quadruple lens (RPQ) turned off, ion beam intensity can be biased by only dead- time effect, which can be precisely corrected online or offline. With the RPQ on, two additional biases, an exponential-like increase of ion beam intensity from 100-100,000 s cps and an apparent dead-time effect (-2 to 2 ns) at high count rates, are observed. They are likely caused by the slightly defocused ions with a wide kinetic energy spread of ~5 eV, 10 times worse than that with thermal source, passing through the RPQ lens to the SEM, which is installed behind the focal plane. Fortunately, the two biases, which are stable during the daily measurements with the same settings of inlet system, source lenses, zoom optics, and RPQ, can be corrected effectively offline to earn accurate U-Th isotopic measurement.

  13. Origins of GEMS Grains

    Science.gov (United States)

    Messenger, S.; Walker, R. M.

    2012-01-01

    Interplanetary dust particles (IDPs) collected in the Earth s stratosphere contain high abundances of submicrometer amorphous silicates known as GEMS grains. From their birth as condensates in the outflows of oxygen-rich evolved stars, processing in interstellar space, and incorporation into disks around new stars, amorphous silicates predominate in most astrophysical environments. Amorphous silicates were a major building block of our Solar System and are prominent in infrared spectra of comets. Anhydrous interplanetary dust particles (IDPs) thought to derive from comets contain abundant amorphous silicates known as GEMS (glass with embedded metal and sulfides) grains. GEMS grains have been proposed to be isotopically and chemically homogenized interstellar amorphous silicate dust. We evaluated this hypothesis through coordinated chemical and isotopic analyses of GEMS grains in a suite of IDPs to constrain their origins. GEMS grains show order of magnitude variations in Mg, Fe, Ca, and S abundances. GEMS grains do not match the average element abundances inferred for ISM dust containing on average, too little Mg, Fe, and Ca, and too much S. GEMS grains have complementary compositions to the crystalline components in IDPs suggesting that they formed from the same reservoir. We did not observe any unequivocal microstructural or chemical evidence that GEMS grains experienced prolonged exposure to radiation. We identified four GEMS grains having O isotopic compositions that point to origins in red giant branch or asymptotic giant branch stars and supernovae. Based on their O isotopic compositions, we estimate that 1-6% of GEMS grains are surviving circumstellar grains. The remaining 94-99% of GEMS grains have O isotopic compositions that are indistinguishable from terrestrial materials and carbonaceous chondrites. These isotopically solar GEMS grains either formed in the Solar System or were completely homogenized in the interstellar medium (ISM). However, the

  14. Building a large-area GEM-based readout chamber for the upgrade of the ALICE TPC

    CERN Document Server

    Gasik, Piotr

    2017-01-01

    A large Time Projection Chamber (TPC) is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019-2020, the LHC will deliver Pb beams colliding at an interaction rate up to 50 kHz, which is about a factor of 100 above the present read-out rate of the TPC. To fully exploit the LHC potential the TPC will be upgraded based on the Gas Electron Multiplier (GEM) technology. A prototype of an ALICE TPC Outer Read-Out Chamber (OROC) was equipped with twelve large-size GEM foils as amplification stage to demonstrate the feasibility of replacing the current Multi Wire Proportional Chambers with the new technology. With a total area of $\\sim$0.76 m$^2$ it is the largest GEM-based detector built to date. The GEM OROC was installed within a test field cage and commissioned with radioactive sources.

  15. Building a large-area GEM-based readout chamber for the upgrade of the ALICE TPC

    Energy Technology Data Exchange (ETDEWEB)

    Gasik, P. [Physik Department E62, Technische Universität München, Garching (Germany); Excellence Cluster ‘Origin and Structure of the Universe’, Garching (Germany)

    2017-02-11

    A large Time Projection Chamber (TPC) is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019–2020, the LHC will deliver Pb beams colliding at an interaction rate up to 50 kHz, which is about a factor of 100 above the present read-out rate of the TPC. To fully exploit the LHC potential the TPC will be upgraded based on the Gas Electron Multiplier (GEM) technology. A prototype of an ALICE TPC Outer Read-Out Chamber (OROC) was equipped with twelve large-size GEM foils as amplification stage to demonstrate the feasibility of replacing the current Multi Wire Proportional Chambers with the new technology. With a total area of ∼0.76 m{sup 2} it is the largest GEM-based detector built to date. The GEM OROC was installed within a test field cage and commissioned with radioactive sources.

  16. Building a large-area GEM-based readout chamber for the upgrade of the ALICE TPC

    International Nuclear Information System (INIS)

    Gasik, P.

    2017-01-01

    A large Time Projection Chamber (TPC) is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019–2020, the LHC will deliver Pb beams colliding at an interaction rate up to 50 kHz, which is about a factor of 100 above the present read-out rate of the TPC. To fully exploit the LHC potential the TPC will be upgraded based on the Gas Electron Multiplier (GEM) technology. A prototype of an ALICE TPC Outer Read-Out Chamber (OROC) was equipped with twelve large-size GEM foils as amplification stage to demonstrate the feasibility of replacing the current Multi Wire Proportional Chambers with the new technology. With a total area of ∼0.76 m 2 it is the largest GEM-based detector built to date. The GEM OROC was installed within a test field cage and commissioned with radioactive sources.

  17. Multiplying dimensions

    CERN Multimedia

    2013-01-01

    A few weeks ago, I had a vague notion of what TED was, and how it worked, but now I’m a confirmed fan. It was my privilege to host CERN’s first TEDx event last Friday, and I can honestly say that I can’t remember a time when I was exposed to so much brilliance in such a short time.   TEDxCERN was designed to give a platform to science. That’s why we called it Multiplying Dimensions – a nod towards the work we do here, while pointing to the broader importance of science in society. We had talks ranging from the most subtle pondering on the nature of consciousness to an eighteen year old researcher urging us to be patient, and to learn from our mistakes. We had musical interludes that included encounters between the choirs of local schools and will.i.am, between an Israeli pianist and an Iranian percussionist, and between Grand Opera and high humour. And although I opened the event by announcing it as a day off from physics, we had a quite brill...

  18. A Muon Tomography Station with GEM Detectors for Nuclear Threat Detection

    Science.gov (United States)

    Staib, Michael; Gnanvo, Kondo; Grasso, Leonard; Hohlmann, Marcus; Locke, Judson; Costa, Filippo; Martoiu, Sorin; Muller, Hans

    2011-10-01

    Muon tomography for homeland security aims at detecting well-shielded nuclear contraband in cargo and imaging it in 3D. The technique exploits multiple scattering of atmospheric cosmic ray muons, which is stronger in dense, high-Z nuclear materials, e.g. enriched uranium, than in low-Z and medium-Z shielding materials. We have constructed and operated a compact Muon Tomography Station (MTS) that tracks muons with six to ten 30 cm x 30 cm Triple Gas Electron Multiplier (GEM) detectors placed on the sides of a 27-liter cubic imaging volume. The 2D strip readouts of the GEMs achieve a spatial resolution of ˜130 μm in both dimensions and the station is operated at a muon trigger rate of ˜20 Hz. The 1,536 strips per GEM detector are read out with the first medium-size implementation of the Scalable Readout System (SRS) developed specifically for Micro-Pattern Gas Detectors by the RD51 collaboration at CERN. We discuss the performance of this MTS prototype and present experimental results on tomographic imaging of high-Z objects with and without shielding.

  19. Performance verification of the Gravity and Extreme Magnetism Small explorer (GEMS) x-ray polarimeter

    Science.gov (United States)

    Enoto, Teruaki; Black, J. Kevin; Kitaguchi, Takao; Hayato, Asami; Hill, Joanne E.; Jahoda, Keith; Tamagawa, Toru; Kaneko, Kenta; Takeuchi, Yoko; Yoshikawa, Akifumi; Marlowe, Hannah; Griffiths, Scott; Kaaret, Philip E.; Kenward, David; Khalid, Syed

    2014-07-01

    Polarimetry is a powerful tool for astrophysical observations that has yet to be exploited in the X-ray band. For satellite-borne and sounding rocket experiments, we have developed a photoelectric gas polarimeter to measure X-ray polarization in the 2-10 keV range utilizing a time projection chamber (TPC) and advanced micro-pattern gas electron multiplier (GEM) techniques. We carried out performance verification of a flight equivalent unit (1/4 model) which was planned to be launched on the NASA Gravity and Extreme Magnetism Small Explorer (GEMS) satellite. The test was performed at Brookhaven National Laboratory, National Synchrotron Light Source (NSLS) facility in April 2013. The polarimeter was irradiated with linearly-polarized monochromatic X-rays between 2.3 and 10.0 keV and scanned with a collimated beam at 5 different detector positions. After a systematic investigation of the detector response, a modulation factor >=35% above 4 keV was obtained with the expected polarization angle. At energies below 4 keV where the photoelectron track becomes short, diffusion in the region between the GEM and readout strips leaves an asymmetric photoelectron image. A correction method retrieves an expected modulation angle, and the expected modulation factor, ~20% at 2.7 keV. Folding the measured values of modulation through an instrument model gives sensitivity, parameterized by minimum detectable polarization (MDP), nearly identical to that assumed at the preliminary design review (PDR).

  20. Performance Verification of the Gravity and Extreme Magnetism Small Explorer GEMS X-Ray Polarimeter

    Science.gov (United States)

    Enoto, Teruaki; Black, J. Kevin; Kitaguchi, Takao; Hayato, Asami; Hill, Joanne E.; Jahoda, Keith; Tamagawa, Toru; Kanako, Kenta; Takeuchi, Yoko; Yoshikawa, Akifumi; hide

    2014-01-01

    olarimetry is a powerful tool for astrophysical observations that has yet to be exploited in the X-ray band. For satellite-borne and sounding rocket experiments, we have developed a photoelectric gas polarimeter to measure X-ray polarization in the 2-10 keV range utilizing a time projection chamber (TPC) and advanced micro-pattern gas electron multiplier (GEM) techniques. We carried out performance verification of a flight equivalent unit (1/4 model) which was planned to be launched on the NASA Gravity and Extreme Magnetism Small Explorer (GEMS) satellite. The test was performed at Brookhaven National Laboratory, National Synchrotron Light Source (NSLS) facility in April 2013. The polarimeter was irradiated with linearly-polarized monochromatic X-rays between 2.3 and 10.0 keV and scanned with a collimated beam at 5 different detector positions. After a systematic investigation of the detector response, a modulation factor greater than or equal to 35% above 4 keV was obtained with the expected polarization angle. At energies below 4 keV where the photoelectron track becomes short, diffusion in the region between the GEM and readout strips leaves an asymmetric photoelectron image. A correction method retrieves an expected modulation angle, and the expected modulation factor, approximately 20% at 2.7 keV. Folding the measured values of modulation through an instrument model gives sensitivity, parameterized by minimum detectable polarization (MDP), nearly identical to that assumed at the preliminary design review (PDR).

  1. GEM detector performance with innovative micro-TPC readout in high magnetic field

    Directory of Open Access Journals (Sweden)

    Garzia I.

    2018-01-01

    Full Text Available Gas detector development is one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detector (MPGD, allowed to overcome several problems related to other types of commonly used detectors, like drift chamber and micro strips detectors, reducing the rate of discharges and providing better radiation tolerance. Among the most used MPGDs are the Gas Electron Multipliers (GEMs. Invented by Sauli in 1997, nowadays GEMs have become an important reality for particle detectors in high energy physics. Commonly deployed as fast timing detectors and triggers, their fast response, high rate capability and high radiation hardness make them also suitable as tracking detectors. The readout scheme is one of the most important features in tracking technology. Analog readout based on the calculation of the center of gravity technique allows to overcome the limit imposed by digital pads, whose spatial resolution is limited by the pitch dimensions. However, the presence of high external magnetic fields can distort the electronic cloud and affect the performance. The development of the micro-TPC reconstruction method brings GEM detectors into a new prospective, improving significantly the spatial resolutionin presence of high magnetic fields. This innovative technique allows to reconstruct the 3-dimensional particle position, as Time Projection Chamber, but within a drift gap of a few millimeters. In these report, the charge centroid and micro-TPC methods are described in details. We discuss the results of several test beams performed with planar chambers in magnetic field. These results are one of the first developments of micro-TPC technique for GEM detectors, which allows to reach unprecedented performance in a high magnetic field of 1 T.

  2. GEM detector performance with innovative micro-TPC readout in high magnetic field

    Science.gov (United States)

    Garzia, I.; Alexeev, M.; Amoroso, A.; Baldini Ferroli, R.; Bertani, M.; Bettoni, D.; Bianchi, F.; Calcaterra, A.; Canale, N.; Capodiferro, M.; Cassariti, V.; Cerioni, S.; Chai, J. Y.; Chiozzi, S.; Cibinetto, G.; Cossio, F.; Cotta Ramusino, A.; De Mori, F.; Destefanis, M.; Dong, J.; Evangelisti, F.; Evangelisti, F.; Farinelli, R.; Fava, L.; Felici, G.; Fioravanti, E.; Gatta, M.; Greco, M.; Lavezzi, L.; Leng, C. Y.; Li, H.; Maggiora, M.; Malaguti, R.; Marcello, S.; Melchiorri, M.; Mezzadri, G.; Mignone, M.; Morello, G.; Pacetti, S.; Patteri, P.; Pellegrino, J.; Pelosi, A.; Rivetti, A.; Rolo, M. D.; Savrié, M.; Scodeggio, M.; Soldani, E.; Sosio, S.; Spataro, S.; Tskhadadze, E.; Verma, S.; Wheadon, R.; Yan, L.

    2018-01-01

    Gas detector development is one of the pillars of the research in fundamental physics. Since several years, a new concept of detectors, called Micro Pattern Gas Detector (MPGD), allowed to overcome several problems related to other types of commonly used detectors, like drift chamber and micro strips detectors, reducing the rate of discharges and providing better radiation tolerance. Among the most used MPGDs are the Gas Electron Multipliers (GEMs). Invented by Sauli in 1997, nowadays GEMs have become an important reality for particle detectors in high energy physics. Commonly deployed as fast timing detectors and triggers, their fast response, high rate capability and high radiation hardness make them also suitable as tracking detectors. The readout scheme is one of the most important features in tracking technology. Analog readout based on the calculation of the center of gravity technique allows to overcome the limit imposed by digital pads, whose spatial resolution is limited by the pitch dimensions. However, the presence of high external magnetic fields can distort the electronic cloud and affect the performance. The development of the micro-TPC reconstruction method brings GEM detectors into a new prospective, improving significantly the spatial resolutionin presence of high magnetic fields. This innovative technique allows to reconstruct the 3-dimensional particle position, as Time Projection Chamber, but within a drift gap of a few millimeters. In these report, the charge centroid and micro-TPC methods are described in details. We discuss the results of several test beams performed with planar chambers in magnetic field. These results are one of the first developments of micro-TPC technique for GEM detectors, which allows to reach unprecedented performance in a high magnetic field of 1 T.

  3. The resistive plate WELL detector as a single stage thick gaseous multiplier detector

    Energy Technology Data Exchange (ETDEWEB)

    Bressler, Shikma; Breskin, Amos; Moleri, Luca; Kumar, Ashwini; Pitt, Michael [Department of Particle Physics and Astrophysics, Weizmann Institute of Science (WIS) (Israel); Kudella, Simon [Institut fuer Experimentelle Kernphysik (IEKP), KIT (Germany)

    2015-07-01

    Gaseous Electron Multiplier (GEM) detector use high electric fields inside the h ole of a foil to achieve a high charge multiplication. As a thicker version of G EMs based on printed circuit board (PCB) structures, Thick Gaseous Electron Multiplier (THGEM) detectors combine the high gain of a GEM foil with the robustness, stability and low production costs of a PCB and allow a large quantity of applications that require the coverage of a large area at low cost and moderate spatial resolution. One application the Weizmann Institute of Science (WIS) develops as a member of the RD51 framework is the Resistive Plate WELL (RPWELL) detector. This single stage detector allows a very stable, discharge free operation at high gain (10{sup 5}). The single stage operation allows a low total height and make s the RPWELL a candidate for the Digital Hadronic Calorimeter (DHCAL) of the International Large Detector (ILD) at the International Linear Collider (ILC). The talk gives an insight into the way the RPWELL works and shows results from the last test beam.

  4. SUPERCOLLIDER: A GEM of a detector

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    Now being prepared as a major experimental facility for the 87- kilometre Superconducting Supercollider (SSC) being built in Ellis County, Texas, is the GEM detector project. GEM thus becomes the companion to the Solenoidal Detector Collaboration (SDC), the first major SSC detector to emerge (March 1992, page 13). This is in keeping with the SSC Laboratory's aim of two major detectors with overlapping and complementary strengths. GEM is designed to observe all SSC signatures, with emphasis on precise measurement of electrons, photons and muons. Hence the name GEM - ''Gammas, Electrons and Muons.'' Design goals are clean signatures for leptons, jets, and missing transverse energy, maximum sensitivity to narrow resonances, and low backgrounds. Also important is maintaining significant capability at high luminosity (10 34 cm -2 s -1 ). GEM has some distinctive features. A key concept is the exterior magnet, surrounding all detector elements. Inside the magnet are a muon tracking system, a precision calorimeter, and a compact central tracker. This allows the muon momentum to be measured the air of the radiation shielded area outside the thick calorimeter, giving both high precision and robustness at high luminosity. A large magnet gives a large lever arm (at least 4 m) for precise muon momentum measurement. Placing the magnet outside also minimizes the material between tracker and calorimeters, so that the calorimeters are limited only by their inherent resolutions

  5. Radiation imaging with optically read out GEM-based detectors

    Science.gov (United States)

    Brunbauer, F. M.; Lupberger, M.; Oliveri, E.; Resnati, F.; Ropelewski, L.; Streli, C.; Thuiner, P.; van Stenis, M.

    2018-02-01

    Modern imaging sensors allow for high granularity optical readout of radiation detectors such as MicroPattern Gaseous Detectors (MPGDs). Taking advantage of the high signal amplification factors achievable by MPGD technologies such as Gaseous Electron Multipliers (GEMs), highly sensitive detectors can be realised and employing gas mixtures with strong scintillation yield in the visible wavelength regime, optical readout of such detectors can provide high-resolution event representations. Applications from X-ray imaging to fluoroscopy and tomography profit from the good spatial resolution of optical readout and the possibility to obtain images without the need for extensive reconstruction. Sensitivity to low-energy X-rays and energy resolution permit energy resolved imaging and material distinction in X-ray fluorescence measurements. Additionally, the low material budget of gaseous detectors and the possibility to couple scintillation light to imaging sensors via fibres or mirrors makes optically read out GEMs an ideal candidate for beam monitoring detectors in high energy physics as well as radiotherapy. We present applications and achievements of optically read out GEM-based detectors including high spatial resolution imaging and X-ray fluorescence measurements as an alternative readout approach for MPGDs. A detector concept for low intensity applications such as X-ray crystallography, which maximises detection efficiency with a thick conversion region but mitigates parallax-induced broadening is presented and beam monitoring capabilities of optical readout are explored. Augmenting high resolution 2D projections of particle tracks obtained with optical readout with timing information from fast photon detectors or transparent anodes for charge readout, 3D reconstruction of particle trajectories can be performed and permits the realisation of optically read out time projection chambers. Combining readily available high performance imaging sensors with compatible

  6. Performance of the full size nGEM detector for the SPIDER experiment

    Energy Technology Data Exchange (ETDEWEB)

    Muraro, A., E-mail: muraro@ifp.cnr.it [Istituto di Fisica del Plasma “P. Caldirola” – CNR, Milan (Italy); Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Croci, G. [Istituto di Fisica del Plasma “P. Caldirola” – CNR, Milan (Italy); Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Sez. INFN Milano-Bicocca, Milano (Italy); Albani, G. [Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Claps, G. [Laboratori Nazionali di Frascati – INFN, Frascati (Italy); Cavenago, M. [Laboratori Nazionali di Legnaro – INFN, Legnaro (Italy); Cazzaniga, C. [Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Dalla Palma, M. [Consorzio RFX, Padova (Italy); Grosso, G. [Istituto di Fisica del Plasma “P. Caldirola” – CNR, Milan (Italy); Murtas, F. [Laboratori Nazionali di Frascati – INFN, Frascati (Italy); Pasqualotto, R. [Consorzio RFX, Padova (Italy); Perelli Cippo, E. [Istituto di Fisica del Plasma “P. Caldirola” – CNR, Milan (Italy); Rebai, M. [Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Tardocchi, M.; Tollin, M. [Istituto di Fisica del Plasma “P. Caldirola” – CNR, Milan (Italy); Gorini, G. [Dipartimento di Fisica “G. Occhialini”, University of Milano-Bicocca (Italy); Sez. INFN Milano-Bicocca, Milano (Italy)

    2016-03-21

    The ITER neutral beam test facility under construction in Padova will host two experimental devices: SPIDER, a 100 kV negative H/D RF beam source, and MITICA, a full scale, 1 MeV deuterium beam injector. SPIDER will start operations in 2016 while MITICA is expected to start during 2019. Both devices feature a beam dump used to stop the produced deuteron beam. Detection of fusion neutrons produced between beam-deuterons and dump-implanted deuterons will be used as a means to resolve the horizontal beam intensity profile. The neutron detection system will be placed right behind the beam dump, as close to the neutron emitting surface as possible thus providing the map of the neutron emission on the beam dump surface. The system uses nGEM neutron detectors. These are Gas Electron Multiplier detectors equipped with a cathode that also serves as neutron–proton converter foil. The cathode is designed to ensure that most of the detected neutrons at a point of the nGEM surface are emitted from the corresponding beamlet footprint (with dimensions of about 40×22 mm{sup 2}) on the dump front surface. The size of the nGEM detector for SPIDER is 352 mm×200 mm. Several smaller size prototypes have been successfully made in the last years and the experience gained on these detectors has led to the production of the full size detector for SPIDER during 2014. This nGEM has a read-out board made of 256 pads (arranged in a 16×16 matrix) each with a dimension of 22 mm×13 mm. This paper describes the production of this detector and its tests (in terms of beam profile reconstruction capability, uniformity over the active area, gamma rejection capability and time stability) performed on the ROTAX beam-line at the ISIS spallation source (Didcot-UK).

  7. Performance of the full size nGEM detector for the SPIDER experiment

    International Nuclear Information System (INIS)

    Muraro, A.; Croci, G.; Albani, G.; Claps, G.; Cavenago, M.; Cazzaniga, C.; Dalla Palma, M.; Grosso, G.; Murtas, F.; Pasqualotto, R.; Perelli Cippo, E.; Rebai, M.; Tardocchi, M.; Tollin, M.; Gorini, G.

    2016-01-01

    The ITER neutral beam test facility under construction in Padova will host two experimental devices: SPIDER, a 100 kV negative H/D RF beam source, and MITICA, a full scale, 1 MeV deuterium beam injector. SPIDER will start operations in 2016 while MITICA is expected to start during 2019. Both devices feature a beam dump used to stop the produced deuteron beam. Detection of fusion neutrons produced between beam-deuterons and dump-implanted deuterons will be used as a means to resolve the horizontal beam intensity profile. The neutron detection system will be placed right behind the beam dump, as close to the neutron emitting surface as possible thus providing the map of the neutron emission on the beam dump surface. The system uses nGEM neutron detectors. These are Gas Electron Multiplier detectors equipped with a cathode that also serves as neutron–proton converter foil. The cathode is designed to ensure that most of the detected neutrons at a point of the nGEM surface are emitted from the corresponding beamlet footprint (with dimensions of about 40×22 mm"2) on the dump front surface. The size of the nGEM detector for SPIDER is 352 mm×200 mm. Several smaller size prototypes have been successfully made in the last years and the experience gained on these detectors has led to the production of the full size detector for SPIDER during 2014. This nGEM has a read-out board made of 256 pads (arranged in a 16×16 matrix) each with a dimension of 22 mm×13 mm. This paper describes the production of this detector and its tests (in terms of beam profile reconstruction capability, uniformity over the active area, gamma rejection capability and time stability) performed on the ROTAX beam-line at the ISIS spallation source (Didcot-UK).

  8. Conceptual design and development of GEM based detecting system for tomographic tungsten focused transport monitoring

    Science.gov (United States)

    Chernyshova, M.; Czarski, T.; Malinowski, K.; Kowalska-Strzęciwilk, E.; Poźniak, K.; Kasprowicz, G.; Zabołotny, W.; Wojeński, A.; Kolasiński, P.; Mazon, D.; Malard, P.

    2015-10-01

    Implementing tungsten as a plasma facing material in ITER and future fusion reactors will require effective monitoring of not just its level in the plasma but also its distribution. That can be successfully achieved using detectors based on Gas Electron Multiplier (GEM) technology. This work presents the conceptual design of the detecting unit for poloidal tomography to be tested at the WEST project tokamak. The current stage of the development is discussed covering aspects which include detector's spatial dimensions, gas mixtures, window materials and arrangements inside and outside the tokamak ports, details of detector's structure itself and details of the detecting module electronics. It is expected that the detecting unit under development, when implemented, will add to the safe operation of tokamak bringing the creation of sustainable nuclear fusion reactors a step closer. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  9. Proceedings of the GEM Collaboration Meeting

    International Nuclear Information System (INIS)

    Bojowald, J.; Ilieva, I.; Klimala, W.; Machner, H.; Razen, B.; Kliczewski, S.; Magiera, A.; Smyrski, J.; Roy, B.J.; Urban, J.

    1997-11-01

    The main subject of the GEM meeting were: meson production near threshold, mesic atoms, nuclear resonances, symmetry violation, light ions structure and interactions. Additionally some apparatus problems like electronic equipment and charged particle detector have been discussed. The volume contains copies of transparencies supplied by the authors which are not normal full texts of papers

  10. Gamma-to-electron magnetic spectrometer (GEMS): An energy-resolved {gamma}-ray diagnostic for the National Ignition Facility

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Y.; Herrmann, H. W.; Mack, J. M.; Young, C. S.; Barlow, D. B.; Schillig, J. B.; Sims, J. R. Jr.; Lopez, F. E.; Mares, D.; Oertel, J. A.; Hayes-Sterbenz, A. C. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Hilsabeck, T. J.; Wu, W. [General Atomics, PO Box 85608, San Diego, California 92186 (United States); Moy, K. [National Security Technologies, Special Technologies Laboratory, Santa Barbara, California 93111 (United States); Stoeffl, W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2012-10-15

    The gamma-to-electron magnetic spectrometer, having better than 5% energy resolution, is proposed to resolve {gamma}-rays in the range of E{sub o}{+-} 20% in single shot, where E{sub o} is the central energy and is tunable from 2 to 25 MeV. Gamma-rays from inertial confinement fusion implosions interact with a thin Compton converter (e.g., beryllium) located at approximately 300 cm from the target chamber center (TCC). Scattered electrons out of the Compton converter enter an electromagnet placed outside the NIF chamber (approximately 600 cm from TCC) where energy selection takes place. The electromagnet provides tunable E{sub o} over a broad range in a compact manner. Energy resolved electrons are measured by an array of quartz Cherenkov converters coupled to photomultipliers. Given 100 detectable electrons in the energy bins of interest, 3 Multiplication-Sign 10{sup 14} minimum deuterium/tritium (DT) neutrons will be required to measure the 4.44 MeV {sup 12}C {gamma}-rays assuming 200 mg/cm{sup 2} plastic ablator areal density and 3 Multiplication-Sign 10{sup 15} minimum DT neutrons to measure the 16.75 MeV DT {gamma}-ray line.

  11. High signal-to-noise ratio sensing with Shack–Hartmann wavefront sensor based on auto gain control of electron multiplying CCD

    International Nuclear Information System (INIS)

    Zhu Zhao-Yi; Li Da-Yu; Hu Li-Fa; Mu Quan-Quan; Yang Cheng-Liang; Cao Zhao-Liang; Xuan Li

    2016-01-01

    High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device (EMCCD) applied in the Shack–Hartmann wavefront sensor (S–H WFS) in adaptive optics (AO). However, when the brightness of the target changes in a large scale, the fixed electron multiplying (EM) gain will not be suited to the sensing limitation. Therefore an auto-gain-control method based on the brightness of light-spots array in S–H WFS is proposed in this paper. The control value is the average of the maximum signals of every light spot in an array, which has been demonstrated to be kept stable even under the influence of some noise and turbulence, and sensitive enough to the change of target brightness. A goal value is needed in the control process and it is predetermined based on the characters of EMCCD. Simulations and experiments have demonstrated that this auto-gain-control method is valid and robust, the sensing SNR reaches the maximum for the corresponding signal level, and especially is greatly improved for those dim targets from 6 to 4 magnitude in the visual band. (special topic)

  12. A new Slow Control and Run Initialization Byte-wise Environment (SCRIBE) for the quality control of mass-produced CMS GEM detectors

    CERN Document Server

    Colafranceschi, Stefano

    2016-01-01

    The CMS collaboration aims at improving the muon trigger and tracking performance at the HL-LHC by installing new Gas Electron Multiplier (GEM) detectors in the endcaps of the CMS experiment. Construction and commissioning of GEM detectors for the first muon endcap stations is ramping up in several laboratories using common quality control protocols. The SCRIBE framework is a scalable and cross-platform web-based application for the RD51 Scalable Readout System (SRS) that controls data acquisition and analyzes data in near real time. It has been developed mainly to simplify and standardize measurements of the GEM detector response uniformities with x-rays across all production sites. SCRIBE works with zero suppression of raw SRS pulse height data. This has increased acquisition rates to 5 kHz for a CMS GEM detector with 3072 strips and allows strip-by-strip response comparisons with a few hours of data taking. SCRIBE also manages parallel data reconstruction to provide near real-time feedback on the detector ...

  13. Ion space-charge effects in multi-GEM detectors: challenges and possible solutions for future applications

    CERN Document Server

    AUTHOR|(CDS)2079251; Streli, Christina

    Gaseous Electron Multiplier (GEM) detectors are well known both for stable operation under irradiation with high particle fluxes and high achievable effective gains. The aim of this thesis is two-fold: to investigate the limits of GEM detector operation due to space-charge effects, and to develop a means to reduce the magnitude of the observed effects and thus extend those limitations. The first part of the thesis presents a comprehensive study of the intrinsic limits of triple-GEM detectors under exposure to very high fluxes of soft X-rays or operation at very large effective gains. The behaviour of the effective gain, ion back-flow and the pulse-height spectra is explained in terms of the movement and accumulation of positive ions throughout the detector volume, resulting in distortions of the transfer and amplification fields. Numerical computations, and measurements on double-stage and single-stage detectors confirm the model describing the observed effects. Discussions on ways to extend the limits of gas...

  14. Fast drift CRID with GEM

    CERN Document Server

    Vavra, J; McCulloch, M; Stiles, P; Sauli, Fabio

    1999-01-01

    The only available technique at the present time, to perform particle identification up to 40-50 GeV/c in a 4 pi solenoidal geometry using the Cherenkov ring imaging method is the use of gaseous detectors filled with either TMAE or TEA photocathodes, and a combination of the gaseous, and solid or liquid radiators. If one would consider building such a device, one may want to investigate alternative methods of building a single-electron detector. This paper investigates the feasibility of using the GEM together with a simple MWPC detector employing 33 mu m diameter carbon wires to obtain a second coordinate. The results are compared to the CRID single-electron detector.

  15. Development of the GEM-TPC X-ray Polarimeter with the Scalable Readout System

    Directory of Open Access Journals (Sweden)

    Kitaguchi Takao

    2018-01-01

    Full Text Available We have developed a gaseous Time Projection Chamber (TPC containing a single-layered foil of a gas electron multiplier (GEM to open up a new window on cosmic X-ray polarimetry in the 2–10 keV band. The micro-pattern TPC polarimeter in combination with the Scalable Readout System produced by the RD51 collaboration has been built as an engineering model to optimize detector parameters and improve polarimeter sensitivity. The polarimeter was characterized with unpolarized X-rays from an X-ray generator in a laboratory and polarized X-rays on the BL32B2 beamline at the SPring-8 synchrotron radiation facility. Preliminary results show that the polarimeter has a comparable modulation factor to a prototype of the flight one.

  16. Stability studies on GEM prototypes for the upgrade of the ALICE TPC

    CERN Document Server

    Cortinas Rodriguo Gaston, CRG

    2013-01-01

    In this work we show results of experiments aiming to understand the stability of a Gas Electron Multiplier (GEM) detector. While operating the detector, we monitor temperature, pressure and humidity in order to understand the contribution of each of these parameters to the behaviour of the devise. We also use a Single Wire proportional counter as a reference detector so to keep track of the gain fluctuations given by external influences (pressure, temperature, gas composition, etc.). In this way it is possible to spot fluctuation due to the intrinsic properties of these new detectors. A special effort is devoted to explaining and discussing different experimental drawbacks that appeared on the way in order to set a precedent, and as far as possible to avoid them in future experiences.

  17. Tomographic capabilities of the new GEM based SXR diagnostic of WEST

    Science.gov (United States)

    Jardin, A.; Mazon, D.; O'Mullane, M.; Mlynar, J.; Loffelmann, V.; Imrisek, M.; Chernyshova, M.; Czarski, T.; Kasprowicz, G.; Wojenski, A.; Bourdelle, C.; Malard, P.

    2016-07-01

    The tokamak WEST (Tungsten Environment in Steady-State Tokamak) will start operating by the end of 2016 as a test bed for the ITER divertor components in long pulse operation. In this context, radiative cooling of heavy impurities like tungsten (W) in the Soft X-ray (SXR) range [0.1 keV; 20 keV] is a critical issue for the plasma core performances. Thus reliable tools are required to monitor the local impurity density and avoid W accumulation. The WEST SXR diagnostic will be equipped with two new GEM (Gas Electron Multiplier) based poloidal cameras allowing to perform 2D tomographic reconstructions in tunable energy bands. In this paper tomographic capabilities of the Minimum Fisher Information (MFI) algorithm developed for Tore Supra and upgraded for WEST are investigated, in particular through a set of emissivity phantoms and the standard WEST scenario including reconstruction errors, influence of noise as well as computational time.

  18. Gas scintillation glass GEM detector for high-resolution X-ray imaging and CT

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, T., E-mail: fujiwara-t@aist.go.jp [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Mitsuya, Y. [Nuclear Professional School, The University of Tokyo, Tokai, Naka, Ibaraki 319-1188 (Japan); Fushie, T. [Radiment Lab. Inc., Setagaya, Tokyo 156-0044 (Japan); Murata, K.; Kawamura, A.; Koishikawa, A. [XIT Co., Naruse, Machida, Tokyo 194-0045 (Japan); Toyokawa, H. [Research Institute for Measurement and Analytical Instrumentation, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568 (Japan); Takahashi, H. [Institute of Engineering Innovation, School of Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8654 (Japan)

    2017-04-01

    A high-spatial-resolution X-ray-imaging gaseous detector has been developed with a single high-gas-gain glass gas electron multiplier (G-GEM), scintillation gas, and optical camera. High-resolution X-ray imaging of soft elements is performed with a spatial resolution of 281 µm rms and an effective area of 100×100 mm. In addition, high-resolution X-ray 3D computed tomography (CT) is successfully demonstrated with the gaseous detector. It shows high sensitivity to low-energy X-rays, which results in high-contrast radiographs of objects containing elements with low atomic numbers. In addition, the high yield of scintillation light enables fast X-ray imaging, which is an advantage for constructing CT images with low-energy X-rays.

  19. Fiber Bragg Grating sensors for deformation monitoring of GEM foils in HEP detectors

    CERN Document Server

    AUTHOR|(CDS)2071648; Bianco, S; Caponero, M; Muhammad, S; Passamonti, L; Piccolo, D; Pierluigi, D; Raffone, G; Russo, A; Saviano, G

    2015-01-01

    Fiber Bragg Grating (FBG) sensors have been so far mainly used in high energy physics (HEP) as high precision positioning and re-positioning sensors and as low cost, easy to mount, radiation hard and low space- consuming temperature and humidity devices. FBGs are also commonly used for very precise strain measurements. In this work we present a novel use of FBGs as flatness and mechanical tensioning sensors applied to the wide Gas Electron Multiplier (GEM) foils of the GE1/1 chambers of the Compact Muon Solenoid (CMS) experiment at Large Hadron Collider (LHC) of CERN. A network of FBG sensors has been used to determine the optimal mechanical tension applied and to characterize the mechanical stress applied to the foils. The preliminary results of the test performed on a full size GE1/1 final prototype and possible future developments will be discussed.

  20. A dynamic method for charging-up calculations: the case of GEM

    CERN Document Server

    Correia, P M M; Azevedo, C D R; Silva, A L M; Veenhof, R; Nemallapudi, Mythra Varun; Veloso, J F C A

    2014-01-01

    The simulation of Micro Pattern Gaseous Detectors (MPGDs) signal response is an important and powerful tool for the design and optimization of such detectors. However, several attempts to simulate exactly the effective charge gain have not been completely successful. Namely, the gain stability over time has not been fully understood. Charging-up of the insulator surfaces have been pointed as one of the responsible for the difference between experimental and Monte Carlo results. This work describes two iterative methods to simulate the charging-up in one MPGD device, the Gas Electron Multiplier (GEM). The first method uses a constant step for avalanches time evolution, very detailed, but slower to compute. The second method uses a dynamic step that improves the computing time. Good agreement between both methods was reached. Despite of comparison with experimental results shows that charging-up plays an important role in detectors operation, should not be the only responsible for the difference between simulat...

  1. Complete Tem-Tomography: 3D Structure of Gems Cluster

    Science.gov (United States)

    Matsuno, J.; Miyake, A.; Tsuchiyama, A.; Messenger, S.; Nakamura-Messenger, K.

    2015-01-01

    GEMS (glass with embedded metal and sulfide) grains in interplanetary dust particles (IDPs) are considered to be one of the ubiquitous and fundamental building blocks of solids in the Solar System. They have been considered to be interstellar silicate dust that survived various metamorphism or alteration processes in the protoplanetary disk but the elemental and isotopic composition measurements suggest that most of them have been formed in the protoplanetary disk as condensates from high temperature gas. This formation model is also supported by the formation of GEMS-like grains with respect to the size, mineral assemblage, texture and infrared spectrum by condensation experiments from mean GEMS composition materials. Previous GEMS studies were performed only with 2D observation by transmission electron microscopy (TEM) or scanning TEM (STEM). However, the 3D shape and structure of GEMS grains and the spatial distribution of Fe/FeS's has critical information about their formation and origin. Recently, the 3D structure of GEMS grains in ultrathin sections of cluster IDPs was revealed by electron tomography using a TEM/STEM (JEM-2100F, JEOL). However, CT images of thin sections mounted on Cu grids acquired by conventional TEM-tomography are limited to low tilt angles (e. g., less than absolute value of 75 deg. In fact, previous 3D TEM observations of GEMS were affected by some artifacts related to the limited tilt range in the TEM used. Complete tomographic images should be acquired by rotating the sample tilt angle over a range of more than absolute value of 80 deg otherwise the CT images lose their correct structures. In order to constrain the origin and formation process of GEMS grains more clearly, we performed complete electron tomography for GEMS grains. Here we report the sample preparation method we have developed for this study, and the preliminary results.

  2. COINCIDENCES BETWEEN ELECTRONS AND TARGET IONS TO IDENTIFY CAPTURE CHANNELS IN COLLISIONS OF MULTIPLY CHARGED IONS ON GAS TARGETS

    NARCIS (Netherlands)

    POSTHUMUS, JH; MORGENSTERN, R

    1992-01-01

    We have investigated multielectron capture processes in collisions of Ar9+ on Ar by measuring the resulting Auger electrons in coincidence with charge-state-analyzed target ions. In this way it was possible to reconstruct partial electron energy spectra, each corresponding to a particular number of

  3. New Approach for 2D Readout of GEM Detectors

    International Nuclear Information System (INIS)

    Hasell, Douglas K.

    2011-01-01

    Detectors based on Gas Electron Multiplication (GEM) technology are becoming more and more widely used in nuclear and high energy physics and are being applied in astronomy, medical physics, industry, and homeland security. GEM detectors are thin, low mass, insensitive to magnetic fields, and can currently provide position resolutions down to ∼50 microns. However, the designs for reconstructing the position, in two dimensions (2D), of the charged particles striking a GEM detector are often complicated to fabricate and expensive. The objective of this proposal is to investigate a simpler procedure for producing the two dimensional readout layer of GEM detectors using readily available printed circuit board technology which can be tailored to the detector requirements. We will use the established GEM laboratory and facilities at M.I.T. currently employed in developing GEM detectors for the STAR forward tracking upgrade to simplify the testing and evaluation of the new 2D readout designs. If this new design proves successful it will benefit future nuclear and high energy physics experiments already being planned and will similarly extend and simplify the application of GEM technology to other branches of science, medicine, and industry. These benefits would be not only in lower costs for fabrication but also it increased flexibility for design and application.

  4. Charging of insulators by multiply-charged-ion impact probed by slowing down of fast binary-encounter electrons

    Science.gov (United States)

    de Filippo, E.; Lanzanó, G.; Amorini, F.; Cardella, G.; Geraci, E.; Grassi, L.; La Guidara, E.; Lombardo, I.; Politi, G.; Rizzo, F.; Russotto, P.; Volant, C.; Hagmann, S.; Rothard, H.

    2010-12-01

    The interaction of ion beams with insulators leads to charging-up phenomena, which at present are under investigation in connection with guiding phenomena in nanocapillaries with possible application in nanofocused beams. We studied the charging dynamics of insulating foil targets [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Ag, and Xe at 40, 23, 40, and 30 MeV/u, respectively) via the measurement of the slowing down of fast binary-encounter electrons. Also, sandwich targets (Mylar covered with a thin Au layer on both surfaces) and Mylar with Au on only one surface were used. Fast-electron spectra were measured by the time-of-flight method at the superconducting cyclotron of Laboratori Nazionali del Sud (LNS) Catania. The charge buildup leads to target-material-dependent potentials of the order of 6.0 kV for Mylar and 2.8 kV for PP. The sandwich targets, surprisingly, show the same behavior as the insulating targets, whereas a single Au layer on the electron and ion exit side strongly suppresses the charging phenomenon. The accumulated number of projectiles needed for charging up is inversely proportional to electronic energy loss. Thus, the charging up is directly related to emission of secondary electrons.

  5. Charging of insulators by multiply-charged-ion impact probed by slowing down of fast binary-encounter electrons

    International Nuclear Information System (INIS)

    De Filippo, E.; Lanzano, G.; Cardella, G.; Amorini, F.; Geraci, E.; Grassi, L.; Politi, G.; La Guidara, E.; Lombardo, I.; Rizzo, F.; Russotto, P.; Volant, C.; Hagmann, S.; Rothard, H.

    2010-01-01

    The interaction of ion beams with insulators leads to charging-up phenomena, which at present are under investigation in connection with guiding phenomena in nanocapillaries with possible application in nanofocused beams. We studied the charging dynamics of insulating foil targets [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Ag, and Xe at 40, 23, 40, and 30 MeV/u, respectively) via the measurement of the slowing down of fast binary-encounter electrons. Also, sandwich targets (Mylar covered with a thin Au layer on both surfaces) and Mylar with Au on only one surface were used. Fast-electron spectra were measured by the time-of-flight method at the superconducting cyclotron of Laboratori Nazionali del Sud (LNS) Catania. The charge buildup leads to target-material-dependent potentials of the order of 6.0 kV for Mylar and 2.8 kV for PP. The sandwich targets, surprisingly, show the same behavior as the insulating targets, whereas a single Au layer on the electron and ion exit side strongly suppresses the charging phenomenon. The accumulated number of projectiles needed for charging up is inversely proportional to electronic energy loss. Thus, the charging up is directly related to emission of secondary electrons.

  6. Live event reconstruction in an optically read out GEM-based TPC

    Science.gov (United States)

    Brunbauer, F. M.; Galgóczi, G.; Gonzalez Diaz, D.; Oliveri, E.; Resnati, F.; Ropelewski, L.; Streli, C.; Thuiner, P.; van Stenis, M.

    2018-04-01

    Combining strong signal amplification made possible by Gaseous Electron Multipliers (GEMs) with the high spatial resolution provided by optical readout, highly performing radiation detectors can be realized. An optically read out GEM-based Time Projection Chamber (TPC) is presented. The device permits 3D track reconstruction by combining the 2D projections obtained with a CCD camera with timing information from a photomultiplier tube. Owing to the intuitive 2D representation of the tracks in the images and to automated control, data acquisition and event reconstruction algorithms, the optically read out TPC permits live display of reconstructed tracks in three dimensions. An Ar/CF4 (80/20%) gas mixture was used to maximize scintillation yield in the visible wavelength region matching the quantum efficiency of the camera. The device is integrated in a UHV-grade vessel allowing for precise control of the gas composition and purity. Long term studies in sealed mode operation revealed a minor decrease in the scintillation light intensity.

  7. A Prototype Combination TPC Cherenkov Detector with GEM Readout for Tracking and Particle Identification and its Potential Use at an Electron Ion Collider

    Directory of Open Access Journals (Sweden)

    Woody Craig

    2018-01-01

    Full Text Available A prototype detector is being developed which combines the functions of a Time Projection Chamber for charged particle tracking and a Cherenkov detector for particle identification. The TPC consists of a 10×10×10 cm3 drift volume where the charge is drifted to a 10×10 cm2 triple GEM detector. The charge is measured on a readout plane consisting of 2×10 mm2 chevron pads which provide a spatial resolution ∼ 100 μm per point in the chevron direction along with dE/dx information. The Cherenkov portion of the detector consists of a second 10×10 cm2 triple GEM with a photosensitive CsI photocathode on the top layer. This detector measures Cherenkov light produced in the drift gas of the TPC by high velocity particles which are above threshold. CF4 or CF4 mixtures will be used as the drift gas which are highly transparent to UV light and can provide excellent efficiency for detecting Cherenkov photons. The drift gas is also used as the operating gas for both GEM detectors. The prototype detector has been constructed and is currently being tested in the lab with sources and cosmic rays, and additional tests are planned in the future to study the detector in a test beam.

  8. A Prototype Combination TPC Cherenkov Detector with GEM Readout for Tracking and Particle Identification and its Potential Use at an Electron Ion Collider

    Science.gov (United States)

    Woody, Craig; Azmoun, Babak; Majka, Richard; Phipps, Michael; Purschke, Martin; Smirnov, Nikolai

    2018-02-01

    A prototype detector is being developed which combines the functions of a Time Projection Chamber for charged particle tracking and a Cherenkov detector for particle identification. The TPC consists of a 10×10×10 cm3 drift volume where the charge is drifted to a 10×10 cm2 triple GEM detector. The charge is measured on a readout plane consisting of 2×10 mm2 chevron pads which provide a spatial resolution ˜ 100 μm per point in the chevron direction along with dE/dx information. The Cherenkov portion of the detector consists of a second 10×10 cm2 triple GEM with a photosensitive CsI photocathode on the top layer. This detector measures Cherenkov light produced in the drift gas of the TPC by high velocity particles which are above threshold. CF4 or CF4 mixtures will be used as the drift gas which are highly transparent to UV light and can provide excellent efficiency for detecting Cherenkov photons. The drift gas is also used as the operating gas for both GEM detectors. The prototype detector has been constructed and is currently being tested in the lab with sources and cosmic rays, and additional tests are planned in the future to study the detector in a test beam.

  9. Graphics gems V (Macintosh version)

    CERN Document Server

    Paeth, Alan W

    1995-01-01

    Graphics Gems V is the newest volume in The Graphics Gems Series. It is intended to provide the graphics community with a set of practical tools for implementing new ideas and techniques, and to offer working solutions to real programming problems. These tools are written by a wide variety of graphics programmers from industry, academia, and research. The books in the series have become essential, time-saving tools for many programmers.Latest collection of graphics tips in The Graphics Gems Series written by the leading programmers in the field.Contains over 50 new gems displaying some of t

  10. Graphics Gems III IBM version

    CERN Document Server

    Kirk, David

    1994-01-01

    This sequel to Graphics Gems (Academic Press, 1990), and Graphics Gems II (Academic Press, 1991) is a practical collection of computer graphics programming tools and techniques. Graphics Gems III contains a larger percentage of gems related to modeling and rendering, particularly lighting and shading. This new edition also covers image processing, numerical and programming techniques, modeling and transformations, 2D and 3D geometry and algorithms,ray tracing and radiosity, rendering, and more clever new tools and tricks for graphics programming. Volume III also includes a

  11. SXR measurement and W transport survey using GEM tomographic system on WEST

    Science.gov (United States)

    Mazon, D.; Jardin, A.; Malard, P.; Chernyshova, M.; Coston, C.; Malard, P.; O'Mullane, M.; Czarski, T.; Malinowski, K.; Faisse, F.; Ferlay, F.; Verger, J. M.; Bec, A.; Larroque, S.; Kasprowicz, G.; Wojenski, A.; Pozniak, K.

    2017-11-01

    Measuring Soft X-Ray (SXR) radiation (0.1-20 keV) of fusion plasmas is a standard way of accessing valuable information on particle transport. Since heavy impurities like tungsten (W) could degrade plasma core performances and cause radiative collapses, it is necessary to develop new diagnostics to be able to monitor the impurity distribution in harsh fusion environments like ITER. A gaseous detector with energy discrimination would be a very good candidate for this purpose. The design and implementation of a new SXR diagnostic developed for the WEST project, based on a triple Gas Electron Multiplier (GEM) detector is presented. This detector works in photon counting mode and presents energy discrimination capabilities. The SXR system is composed of two 1D cameras (vertical and horizontal views respectively), located in the same poloidal cross-section to allow for tomographic reconstruction. An array (20 cm × 2 cm) consists of up to 128 detectors in front of a beryllium pinhole (equipped with a 1 mm diameter diaphragm) inserted at about 50 cm depth inside a cooled thimble in order to retrieve a wide plasma view. Acquisition of low energy spectrum is insured by a helium buffer installed between the pinhole and the detector. Complementary cooling systems (water) are used to maintain a constant temperature (25oC) inside the thimble. Finally a real-time automatic extraction system has been developed to protect the diagnostic during baking phases or any overheating unwanted events. Preliminary simulations of plasma emissivity and W distribution have been performed for WEST using a recently developed synthetic diagnostic coupled to a tomographic algorithm based on the minimum Fisher information (MFI) inversion method. First GEM acquisitions are presented as well as estimation of transport effect in presence of ICRH on W density reconstruction capabilities of the GEM.

  12. Comparison of Experiment and Simulation of the triple GEM-Based Fast Neutron Detector

    International Nuclear Information System (INIS)

    Wang Xiao-Dong; Luo Wen; Zhang Jun-Wei; Yang He-Run; Duan Li-Min; Lu Chen-Gui; Hu Rong-Jiang; Hu Bi-Tao; Zhang Chun-Hui; Yang Lei; Zhou Jian-Rong; An Lv-Xing

    2015-01-01

    A detector for fast neutrons based on a 10 × 10 cm"2 triple gas electron multiplier (GEM) device is developed and tested. A neutron converter, which is a high density polyethylene (HDPE) layer, is combined with the triple GEM detector cathode and placed inside the detector, in the path of the incident neutrons. The detector is tested by obtaining the energy deposition spectrum with an Am Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou. In the present work we report the results of the tests and compare them with those of simulations. The transport of fast neutrons and their interactions with the different materials in the detector are simulated with the GEANT4 code, to understand the experimental results. The detector displays a clear response to the incident fast neutrons. However, an unexpected disagreement in the energy dependence of the response between the simulated and measured spectra is observed. The neutron sources used in our simulation include deuterium-tritium (DT, 14 MeV), deuterium-deuterium (DD, 2.45 MeV), and Am Be sources. The simulation results also show that among the secondary particles generated by the incident neutron, the main contributions to the total energy deposition are from recoil protons induced in hydrogen-rich HDPE or Kapton (GEM material), and activation photons induced by neutron interaction with Ar atoms. Their contributions account for 90% of the total energy deposition. In addition, the dependence of neutron deposited energy spectrum on the composition of the gas mixture is presented. (paper)

  13. Studies of aging and HV break down problems during development and operation of MSGC and GEM detectors for the inner tracking system of HERA-B

    International Nuclear Information System (INIS)

    Bagaturia, Y.; Baruth, O.; Dreis, H.B.; Eisele, F.; Gorbunov, I.; Gradl, S.; Gradl, W.; Hausmann, S.; Hildebrandt, M.; Hott, T.; Keller, S.; Krauss, C.; Lomonosov, B.; Negodaev, M.; Richter, C.; Robmann, P.; Schmidt, B.; Straumann, U.; Truoel, P.; Visbeck, S.; Walter, T.; Werner, C.; Werthenbach, U.; Zech, G.; Zeuner, T.; Ziegler, M.

    2002-01-01

    The results of 5 years of development of the inner tracking system of the HERA-B experiment and first experience from the data taking period of the year 2000 are reported. The system contains 184 chambers, covering a sensitive area of about (20x20) cm 2 each. The detector is based on microstrip gas counters (MSGCs) with diamond-like coated (DLC) glass wafers and gas electron multipliers (GEMs). The main problems in the development phase were gas discharges in intense hadron beams and aging in a high radiation dose environment. The observation of gas discharges which damage the electrode structure of the MSGC led to the addition of the GEM as a first amplification step. Spurious sparking at the GEM cannot be avoided completely. It does not affect the GEM itself but can produce secondary damage of the MSGC if the electric field between the GEM and the MSGC is above a threshold depending on the operation conditions. We observed that aging does not only depend on the dose but also on the spot size of the irradiated area. Ar-DME mixtures had to be abandoned whereas a mixture of 70% Ar and 30% CO 2 showed no serious aging effects up to about 40 mC/cm deposited charge on the anodes. X-ray measurements indicate that the DLC of the MSGC is deteriorated by the gas amplification process. As a consequence, long-term gain variations are expected. The Inner Tracker has successfully participated in the data taking at HERA-B during summer 2000

  14. Studies of aging and HV break down problems during development and operation of MSGC and GEM detectors for the inner tracking system of HERA-B

    Energy Technology Data Exchange (ETDEWEB)

    Bagaturia, Y.; Baruth, O.; Dreis, H.B.; Eisele, F.; Gorbunov, I.; Gradl, S.; Gradl, W.; Hausmann, S.; Hildebrandt, M.; Hott, T.; Keller, S.; Krauss, C.; Lomonosov, B.; Negodaev, M.; Richter, C.; Robmann, P.; Schmidt, B.; Straumann, U.; Truoel, P.; Visbeck, S.; Walter, T.; Werner, C.; Werthenbach, U.; Zech, G. E-mail: zech@physik.uni-siegen.de; Zeuner, T.; Ziegler, M

    2002-09-01

    The results of 5 years of development of the inner tracking system of the HERA-B experiment and first experience from the data taking period of the year 2000 are reported. The system contains 184 chambers, covering a sensitive area of about (20x20) cm{sup 2} each. The detector is based on microstrip gas counters (MSGCs) with diamond-like coated (DLC) glass wafers and gas electron multipliers (GEMs). The main problems in the development phase were gas discharges in intense hadron beams and aging in a high radiation dose environment. The observation of gas discharges which damage the electrode structure of the MSGC led to the addition of the GEM as a first amplification step. Spurious sparking at the GEM cannot be avoided completely. It does not affect the GEM itself but can produce secondary damage of the MSGC if the electric field between the GEM and the MSGC is above a threshold depending on the operation conditions. We observed that aging does not only depend on the dose but also on the spot size of the irradiated area. Ar-DME mixtures had to be abandoned whereas a mixture of 70% Ar and 30% CO{sub 2} showed no serious aging effects up to about 40 mC/cm deposited charge on the anodes. X-ray measurements indicate that the DLC of the MSGC is deteriorated by the gas amplification process. As a consequence, long-term gain variations are expected. The Inner Tracker has successfully participated in the data taking at HERA-B during summer 2000.

  15. Graphics gems II

    CERN Document Server

    Arvo, James

    1991-01-01

    Graphics Gems II is a collection of articles shared by a diverse group of people that reflect ideas and approaches in graphics programming which can benefit other computer graphics programmers.This volume presents techniques for doing well-known graphics operations faster or easier. The book contains chapters devoted to topics on two-dimensional and three-dimensional geometry and algorithms, image processing, frame buffer techniques, and ray tracing techniques. The radiosity approach, matrix techniques, and numerical and programming techniques are likewise discussed.Graphics artists and comput

  16. Electron transfer from H2 and Ar to stored multiply charged argon ions produced by synchrotron radiation

    International Nuclear Information System (INIS)

    Kravis, S.D.; Church, D.A.; Johnson, B.M.; Meron, M.; Jones, K.W.; Levin, J.C.; Sellin, I.A.; Azuma, Y.; Berrah-Mansour, N.; Berry, H.G.; Druetta, M.

    1992-01-01

    The rate coefficients for electron transfer from Ar and H 2 to Ar q+ ions (3≤q≤6) have been measured using an ion-storage technique in a Penning ion trap. The ions were produced in the trap by K-shell photoionization of Ar atoms, using broadband synchrotron x-ray radiation. K-electron removal resulted in vacancy cascading, yielding a distribution of argon-ion charge states peaked near Ar 4+ . The stored ion gas had an initial temperature near 480 K. The basic data determining the rate coefficients k(Ar q+ ) are the storage time constants of each charge state in the trap, in the presence of a measured pressure of target gas. The results of the measurements (in units of 10 -9 cm 3 s -1 ) are k(Ar 3+ ,H 2 )=4.3(0.7), k(Ar 3+ ,Ar)=1.6(0.2), k(Ar 4+ ,H 2 )=5.2(0.6), k(Ar 4+ ,Ar)=2.5(0.3), k(Ar 5+ ,H 2 )=5.9(0.7), k(Ar 5+ ,Ar)=2.9(0.3), k(Ar 6+ ,H 2 )=8.5(1.2), and k(Ar 6+ ,Ar)=2.5(0.3)

  17. M.C. simulation of GEM neutron beam monitor with 10B

    International Nuclear Information System (INIS)

    Wang Yanfeng; Sun Zhijia; Liu Ben; Zhou Jianrong; Yang Guian; Dong Jing; Xu Hong; Zhou Liang; Huang Guangming; Yang Lei; Li Yi

    2010-01-01

    The neutron beam monitor based on GEM detector has been carefully studied with the Monte-Carlo method in this article. The simulation framework is including the ANSYS and the Garfield, which was used to compute the electric field of GEM foils and simulate the movement of electrons in gas mixture respectively. The GEM foils' focus and extract coefficients have been obtained. According to the primary results, the performing of the monitor is improved. (authors)

  18. Game programming gems

    CERN Document Server

    DeLoura, Mark

    2000-01-01

    For the countless tasks involved in creating a game engine there are an equal number of possible solutions. But instead of spending hours and hours trying to develop your own answers, now you can find out how the pros do it! Game Programming Gems is a hands-on, comprehensive resource packed with a variety of game programming algorithms written by experts from the game industry and edited by Mark DeLoura, former software engineering lead for Nintendo of America, Inc. and now the newly appointed editor-in-chief of Game Developer magazine. From animation and artificial intelligence to Z-buffering, lighting calculations, weather effects, curved surfaces, mutliple layer Internet gaming, to music and sound effects, all of the major techniques needed to develop a competitive game engine are covered. Game Programming Gems is written in a style accessible to individuals with a range of expertise levels. All of the source code for each algorithm is included and can be used by advanced programmers immediately. For aspir...

  19. Development of Large-Area GEM Detectors for the Forward Muon Endcap Upgrade of the CMS Experiment and Search for SM Higgs Boson Decay in the $H\\to\\tau^{+}\\tau^{-}\\to\\mu^{+}\\mu^{-}\\bar{\

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00366476; Gallo, Elisabetta; Raspereza, Alexei

    Gas Electron Multiplier (GEM) technology is being considered for the forward muon upgrade of the Compact Muon Solenoid (CMS) experiment in \\mbox{Phase II} of the CERN LHC. The first GEM Endcap (GE1/1) is going to be installed in the $1.5 < \\mid\\eta\\mid < 2.2$ region of the muon endcapˆ’ mainly to control muon level-1 trigger rates after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by 3,072 radial strips with 453 $\\mu$rad pitch arranged in eight $\\eta$-sectors. A meter-long GE1/1 prototype-III was assembled at Florida Tech and tested in 20-120 GeV hadron beams at Fermilab using Ar/CO$_{2}$ 70:30 and the RD51 Scalable Readout System (SRS). Four GEM detectors with 2-D readout and an average measured azimuthal resolution of 36$\\mu$rad provided precise reference tracks. Construction of this GE1/1 prototype-III detector and its performance in the test beam are described. Strip cluster parameters, detection efficiency, and spatial resolution are studied with position and high voltag...

  20. A comparison using Faraday cups with 1013 Ω amplifiers and a secondary electron multiplier to measure Os isotopes by negative thermal ionization mass spectrometry.

    Science.gov (United States)

    Wang, Guiqin; Sun, Tiantian; Xu, Jifeng

    2017-10-15

    According to the Johnson-Nyquist noise equation, the value of electron noise is proportional to the square root of the resistor value. This relationship gives a theoretical improvement of 100 in the signal/noise ratio by going from 10 11 Ω to 10 13 Ω amplifiers for Faraday detection in thermal ionization mass spectrometry (TIMS). We measured Os isotopes using static Faraday cups with 10 13 Ω amplifiers in negative thermal ionization mass spectrometry (NTIMS) and compared the results with those obtained with 10 11 Ω amplifiers and by peak-hopping on a single secondary electron multiplier (SEM). We analysed large loads of Os (1 μg) at a range of intensities of 187 OsO 3 (0.02-10 mV) in addition to small loads of Os (5-500 pg) to compare the results of the three methods. Using 10 13 Ω amplifiers, the long-term reproducibility determined from Merck Os was 187 Os/ 188 Os = 0.1211 ± 0.0086 and 0.120229 ± 0.000034 at 0.02 mV and 10 mV of 187 OsO 3 intensities. Meanwhile, the analysed JMC Os loadings of 5 and 500 pg showed 187 Os/ 188 Os = 0.10669 ± 0.00036 and 0.106807 ± 0.000023. In comparison, the values measured by the SEM were 187 Os/ 188 Os = 0.10704 ± 0.00056 and 0.10690 ± 0.00013. All errors are in 2 standard deviation (SD). Both the accuracy and the precision determined using the 10 13 Ω amplifiers and the SEM are identical when the Os amounts are within 10-50 pg. However, the former analysis time can be shortened by approximately two-thirds. The SEM measurement is still the most precise method for Os amounts 50 pg. Copyright © 2017 John Wiley & Sons, Ltd.

  1. Study on the novel neutron-to-proton convertor for improving the detection efficiency of a triple GEM based fast neutron detector

    International Nuclear Information System (INIS)

    Wang Xiaodong; Yang Lei; Zhang Chunhui; Hu Bitao; Yang Herun; Zhang Junwei; Ren Zhongguo; Ha Ri-Ba-La; An Luxing

    2015-01-01

    A high-efficiency fast neutron detector prototype based on a triple Gas Electron Multiplier (GEM) detector, which, coupled with a novel multi-layered high-density polyethylene (HDPE) as a neutron-to-proton converter for improving the neutron detection efficiency, is introduced and tested with the Am-Be neutron source in the Institute of Modern Physics (IMP) at Lanzhou in the present work. First, the developed triple GEM detector is tested by measuring its effective gain and energy resolution with "5"5Fe X-ray source to ensure that it has a good performance. The effective gain and obtained energy resolution is 5.0 × 10"4 and around 19.2%, respectively. Secondly, the novel multi-layered HDPE converter is coupled with the cathode of the triple GEM detector making it a high-efficiency fast neutron detector. Its effective neutron response is four times higher than that of the traditional single-layered conversion technique when the converter layer number is 38. (authors)

  2. Properties of thick GEM in low-pressure deuterium

    International Nuclear Information System (INIS)

    Lee, C S; Ota, S; Tokieda, H; Kojima, R; Watanabe, Y N; Uesaka, T

    2014-01-01

    Deuteron inelastic scattering (d, d') provides a promising spectroscopic tool to study nuclear incompressibility. In studies of deuteron inelastic scattering of unstable nuclei, measurements of low-energy recoiled particles is very important. In order to perform these measurements, we are developing a GEM-TPC based gaseous active target, called CAT (Center for nuclear study Active Target), operated with pure deuterium gas. The CAT has been tested with deuterium gas at 1 atm and 100-μm-thick GEMs. The low-pressure operation of CAT is planned in order to improve the detection capability for lower-energy recoil particles. A 400 μm-thick gas electron multiplier (THGEM) was chosen for the low-pressure operation of CAT. However, the properties of THGEM in low-pressure deuterium are currently undocumented. In this work, the performance of THGEM with low-pressure pure deuterium gas has been investigated. The effective gas gain of THGEM has been measured in various conditions using a 5.5-MeV 241 Am alpha source. The effective gas gain was measured for 0.2-, 0.3- and 0.4-atm deuterium gas and a gas gain of about 10 3 was achieved by a double THGEM structure at 0.2 atm. The maximum achieved gain decreased with increasing gas pressure. The dependences of the effective gas gain on the electric field strengths of the drift, transfer and induction regions were investigated. The gain stability as a function of time in hydrogen gas was also tested and a relaxation time of THGEM of about 60 hours was observed with a continuous irradiation of alpha particles, which is significantly longer than previous studies have reported. We have tried to evaluate the gas gain of THGEM in deuterium gas by considering only the Townsend ionization process; however, it turned out that more phenomenological aspects, such as transfer efficiency, should be included in the evaluation. The basic properties of THGEM in low-pressure deuterium have been investigated for the first time

  3. Properties of thick GEM in low-pressure deuterium

    Science.gov (United States)

    Lee, C. S.; Ota, S.; Tokieda, H.; Kojima, R.; Watanabe, Y. N.; Uesaka, T.

    2014-05-01

    Deuteron inelastic scattering (d, d') provides a promising spectroscopic tool to study nuclear incompressibility. In studies of deuteron inelastic scattering of unstable nuclei, measurements of low-energy recoiled particles is very important. In order to perform these measurements, we are developing a GEM-TPC based gaseous active target, called CAT (Center for nuclear study Active Target), operated with pure deuterium gas. The CAT has been tested with deuterium gas at 1 atm and 100-μm-thick GEMs. The low-pressure operation of CAT is planned in order to improve the detection capability for lower-energy recoil particles. A 400 μm-thick gas electron multiplier (THGEM) was chosen for the low-pressure operation of CAT. However, the properties of THGEM in low-pressure deuterium are currently undocumented. In this work, the performance of THGEM with low-pressure pure deuterium gas has been investigated. The effective gas gain of THGEM has been measured in various conditions using a 5.5-MeV 241Am alpha source. The effective gas gain was measured for 0.2-, 0.3- and 0.4-atm deuterium gas and a gas gain of about 103 was achieved by a double THGEM structure at 0.2 atm. The maximum achieved gain decreased with increasing gas pressure. The dependences of the effective gas gain on the electric field strengths of the drift, transfer and induction regions were investigated. The gain stability as a function of time in hydrogen gas was also tested and a relaxation time of THGEM of about 60 hours was observed with a continuous irradiation of alpha particles, which is significantly longer than previous studies have reported. We have tried to evaluate the gas gain of THGEM in deuterium gas by considering only the Townsend ionization process; however, it turned out that more phenomenological aspects, such as transfer efficiency, should be included in the evaluation. The basic properties of THGEM in low-pressure deuterium have been investigated for the first time.

  4. Calculated characteristics of multichannel photoelectron multipliers

    International Nuclear Information System (INIS)

    Vasil'chenko, V.G.; Dajkovskij, A.G.; Milova, N.V.; Rakhmatov, V.E.; Rykalin, V.I.

    1990-01-01

    Structural features and main calculated characteristics of some modifications of position-sensitive two-coordinate multichannel photoelectron multipliers (PEM) with plate-type multiplying systems are described. The presented PEM structures are free from direct optical and ion feedbacks, provide coordinate resolution ≅ 1 mm with efficiency of photoelectron detection ≅ 90%. Capabilities for using silicon field-effect photocathodes, providing electron extraction into vacuum, as well as prospects of using multichannel multiplying systems for readout of the data from solid detectors are considered

  5. Irradiation study on GEM IPC preamp/shaper

    International Nuclear Information System (INIS)

    Kandasamy, A.

    1995-01-01

    The Preamplifier/Shaper Integrated Circuit for the GEM Interpolating Pad Chamber (IPC), designed by Paul. O'Connor, Brookhaven National Laboratory is for amplifying the charge signal from the Pad cathodes into a voltage pulse which goes to the Analog Random Access Memory (ARAM) integrated circuit. The GEM IPC integrated circuit has a SemiGaussian voltage pulse output with a 30ns shaping time. The integrated circuits were fabricated using Harris Semiconductors AVLSI1-RA process in-order for the electronics on the wafer to survive up to 2 mad of ionizing radiation during its operation life time. The details of the electronics on the GEM IPC integrated circuits is explained in the design memorandum by Paul. O'Connor. The purpose of this study is to determine the ability of the electronics on this IC fabricated using the above process to withstand ionizing radiation up to the above mentioned dose level

  6. Mexican gems as thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    Azorin N, J.

    1979-01-01

    The possibility of using naturally ocurring mexican gems as thermoluminescent dosimeters (TLD) was investigated. Twelve types of gems were irradiated with X and gamma rays in order to determinate their dosimetric properties. Three of these gems showed favorable thermoluminescent characteristics compared with commercial thermoluminescent dosimeters. The plots of their thermoluminescent response as a function of gamma dose are straight lines on full log paper in the dose range 10 -2 to 10 2 Gy. The energy dependence is very strong to low energies of the radiation. Their fading was found to be about 5%/yr. and they may be annealed as reused without loss in sensitivity. Therefore, these gems can be used as X and gamma radiation dosimeters. (author)

  7. Electron multiplier for the measurement of an ion current on a mass spectrometer; Multiplicateur d'electrons pour la mesure de courant d'ions sur un spectrometre de masse

    Energy Technology Data Exchange (ETDEWEB)

    Lohez, P; Nief, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1957-07-01

    The apparatus described is designed to measure weak ion currents received at the collector of a mass spectrometer. The report describes successively the study of electron paths in the multiplier by the method of analogy, using rubber membranes, and the practical details of construction of the apparatus. The variation with surface treatment of the secondary emission coefficient of the alloy CuBe containing 2 per cent Be, which makes up the dynodes, and the influence of the voltage on the gain per stage, are discussed. Results of tests regarding: the influence of the ion mass on the gain, the background of the instrument and the energy distribution of the impulses coming out on a high gain multiplier (q.q. 10{sup 7}) are given. Finally the performances of the multiplier are reported. 1- For a low gain (10{sup 4}), precision and reproducibility comparable to the electrometer valve, sensitivity 100 times greater, currents capable of detection 10{sup -17} Ampere. 2- For a high gain (10{sup 7}) and measurement by impulse counting, currents capable of detection 10{sup -19} Ampere. Mounting difficult to use on a mass spectrometer. (author) [French] L'appareil decrit est destine a la mesure des faibles courants d'ions re s au collecteur d'un spectrometre de masse. Le rapport decrit successivement l'etude des trajectoires des electrons dans le multiplicateur, par la methode analogique de la menbrane en caoutchouc, et la realisation pratique de l'appareil. La variation du coefficient d'emission secondaire de l'alliage CuBe a 2 pour cent de Be, constituant les dynodes suivant le traitement des surfaces, et l'influence de la tension sur le gain par etage sont discutees. Des resultats d'essais concernant: l'influence de la masse des ions sur le gain, le bruit de fond de l'appareil et la repartition en energie des impulsions de sortie sur un multiplicateur a gain eleve (q.q. 10{sup 7}) sont donnes. Enfin, sont rapportees les performances du multiplicateur. 1- pour un gain faible

  8. The cylindrical GEM detector of the KLOE-2 experiment

    International Nuclear Information System (INIS)

    Bencivenni, G.; Ciambrone, P.; De Lucia, E.; Domenici, D.; Felici, G.; Fermani, P.; Morello, G.; Branchini, P.; Cicco, A. Di; Czerwinski, E.

    2017-01-01

    The KLOE-2 experiment started its data taking campaign in November 2014 with an upgraded tracking system at the DAΦNE electron-positron collider at the Frascati National Laboratory of INFN. The new tracking device, the Inner Tracker, operated together with the KLOE-2 Drift Chamber, has been installed to improve track and vertex reconstruction capabilities of the experimental apparatus. The Inner Tracker is a cylindrical GEM detector composed of four cylindrical triple-GEM detectors, each provided with an X-V strips-pads stereo readout. Although GEM detectors are already used in high energy physics experiments, this device is considered a frontier detector due to its fully-cylindrical geometry: KLOE-2 is the first experiment benefiting of this novel detector technology. Alignment and calibration of this detector will be presented together with its operating performance and reconstruction capabilities.

  9. The Multiply Handicapped Child.

    Science.gov (United States)

    Wolf, James M., Ed.; Anderson, Robert M., Ed.

    Articles presented in the area of the medical and educational challenge of the multiply handicapped child are an overview of the problem, the increasing challenge, congenital malformations, children whose mothers had rubella, prematurity and deafness, the epidemiology of reproductive casualty, and new education for old problems. Discussions of…

  10. The Multiplier Effect.

    Science.gov (United States)

    Flowers, William L., Jr.; Harris, John B.

    1981-01-01

    The multiplier effect is discussed as it applies to the field of continuing education. The authors' main point is that one grant or contract can, and should, be used as the basis for building organizational competencies and capabilities that will secure other funds. (Author/CT)

  11. ARTROC—a readout ASIC for GEM-based full-field XRF imaging system

    Science.gov (United States)

    Fiutowski, T.; Koperny, S.; Łach, B.; Mindur, B.; Świentek, K.; Wiącek, P.; Dąbrowski, W.

    2017-12-01

    In the paper we report on development of an Application Specific Integrated Circuit (ASIC), called ARTROC, being part of a full-field X-ray fluorescence spectroscopy (XRF) imaging system equipped with a standard three stage Gas Electron Multiplier (GEM) detector of 10×10 cm2 area. The ARTROC consists of 64 independent channels, allowing for simultaneous recording of the amplitudes (energy sub-channel) and time stamps (timing sub-channel) of incoming signals. Thanks to the implemented token-based read out of derandomizing buffers, the ASIC also provides data sparsification and full zero suppression. Reconstruction of the hit positions is performed in an external data acquisition system by matching the time stamps of signals recorded in X- and Y-strips. The amplitude information is used for centre of gravity finding in clusters of signals on neighbouring strips belonging to the same detection events. The ASIC could work in one of six gain modes and one of two speed modes. In a slower mode the maximum count rate per channel is 105/s while in a faster mode it is three times higher. The ARTROC comprises also input protection circuits against possible random discharges inside active detector volume, so it can be used without any additional input components. The ASIC has been designed in 350 nm CMOS process. The basic functionality and parameters have been evaluated using the testability functions implemented in the ASIC design. The ASIC has been also tested in a fully equipped GEM detector set-up with X-rays source.

  12. Use of aluminium plates to simulate the dosimetry of gems during e-beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Fortes, Marcio Z.; Sousa, Fernando N.C. de; Boente, Otavio C., E-mail: mzamboti@aceletron.com.b, E-mail: fernando.nuno@aceletron.com.b, E-mail: otavio@aceletron.com.b [Aceletron Irradiacao Industrial, Rio de Janeiro, RJ (Brazil); Sousa, Nuno R.A., E-mail: engenheiro.nuno.sousa@gmail.co [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Dept. de Engenharia Mecanica

    2009-07-01

    The e-beam technology is used in the industrial irradiation of several products like turf, sterilization of medical products, cosmetics, polymers, food, and gems. More than 70% of the gems commercialized in the world receive treatments similar to those present in nature, including heat, and irradiation, in order to improve their value. Since aluminum has a density similar to that of several commercial gems, this paper presents a study of the penetration of electrons in calibrated aluminum plates simulating several different thicknesses ranging from 5 to 30 mm, and comparing with the one obtained in gems. This allows the monitoring of the dose received by gems during irradiation with e-beam systems measuring the delivered surface dose. This procedure is very important for industrial processing of stones due to the irregularities present on most gems, what makes dosimetry a very complex task. The determination of the thicknesses of the gems for which the surface dose is the lowest dose on the whole product assures the precise determination of the minimum dose received by the gems during industrial processing. (author)

  13. Microwave Frequency Multiplier

    Science.gov (United States)

    Velazco, J. E.

    2017-02-01

    High-power microwave radiation is used in the Deep Space Network (DSN) and Goldstone Solar System Radar (GSSR) for uplink communications with spacecraft and for monitoring asteroids and space debris, respectively. Intense X-band (7.1 to 8.6 GHz) microwave signals are produced for these applications via klystron and traveling-wave microwave vacuum tubes. In order to achieve higher data rate communications with spacecraft, the DSN is planning to gradually furnish several of its deep space stations with uplink systems that employ Ka-band (34-GHz) radiation. Also, the next generation of planetary radar, such as Ka-Band Objects Observation and Monitoring (KaBOOM), is considering frequencies in the Ka-band range (34 to 36 GHz) in order to achieve higher target resolution. Current commercial Ka-band sources are limited to power levels that range from hundreds of watts up to a kilowatt and, at the high-power end, tend to suffer from poor reliability. In either case, there is a clear need for stable Ka-band sources that can produce kilowatts of power with high reliability. In this article, we present a new concept for high-power, high-frequency generation (including Ka-band) that we refer to as the microwave frequency multiplier (MFM). The MFM is a two-cavity vacuum tube concept where low-frequency (2 to 8 GHz) power is fed into the input cavity to modulate and accelerate an electron beam. In the second cavity, the modulated electron beam excites and amplifies high-power microwaves at a frequency that is a multiple integer of the input cavity's frequency. Frequency multiplication factors in the 4 to 10 range are being considered for the current application, although higher multiplication factors are feasible. This novel beam-wave interaction allows the MFM to produce high-power, high-frequency radiation with high efficiency. A key feature of the MFM is that it uses significantly larger cavities than its klystron counterparts, thus greatly reducing power density and arcing

  14. First results of spherical GEMs

    CERN Document Server

    Pinto, Serge Duarte; Brock, Ian; Croci, Gabriele; David, Eric; de Oliveira, Rui; Ropelewski, Leszek; van Stenis, Miranda; Taureg, Hans; Villa, Marco

    2010-01-01

    We developed a method to make GEM foils with a spherical geometry. Tests of this procedure and with the resulting spherical GEMs are presented. Together with a spherical drift electrode, a spherical conversion gap can be formed. This eliminates the parallax error for detection of x-rays, neutrons or UV photons when a gaseous converter is used. This parallax error limits the spatial resolution at wide scattering angles. Besides spherical GEMs, we have developed curved spacers to maintain accurate spacing, and a conical field cage to prevent edge distortion of the radial drift field up to the limit of the angular acceptance of the detector. With these components first tests are done in a setup with a spherical entrance window but a planar readout structure; results will be presented and discussed. A flat readout structure poses difficulties, however. Therefore we will show advanced plans to make a prototype of an entirely spherical double-GEM detector, including a spherical 2D readout structure. This detector w...

  15. Fiscal Multipliers in Ukraine

    OpenAIRE

    Pritha Mitra; Tigran Poghosyan

    2015-01-01

    Amid renewed crisis, falling tax revenues, and rising debt, Ukraine faces serious fiscal consolidation needs. Durable fiscal adjustment can support economic confidence and rebuild buffers but what is its overall impact on growth? How effective are revenue versus spending instruments? Does current or capital spending have a larger impact? Applying a structural vector autoregressive model, this paper finds that Ukraine’s near-term revenue and spending multipliers are well below one. In the medi...

  16. Why Multiply by "g"?

    Science.gov (United States)

    Nelson, Jane Bray

    2012-01-01

    As a new physics teacher, I was explaining how to find the weight of an object sitting on a table near the surface of the Earth. It bothered me when a student asked, "The object is not accelerating so why do you multiply the mass of the object by the acceleration due to gravity?" I answered something like, "That's true, but if the table were not…

  17. Coincident detection of electrons ejected at large angles and target recoil ions produced in multiply ionizing collisions for the 1-MeV/u Oq++Ar collision system

    International Nuclear Information System (INIS)

    Gaither III, C.C.; Breinig, M.; Berryman, J.W.; Hasson, B.F.; Richards, J.D.; Price, K.

    1993-01-01

    The angular distributions of energetic electrons ejected at angles between 45 degree and 135 degree with respect to the incident-beam direction have been measured in coincidence with the charge states of the target recoil ions produced in multiply ionizing collisions for the 1-MeV/u O q+ (q=4,7)+Ar collision systems. These measurements have been made for ∼179-, ∼345-, and ∼505-eV electrons. Additionally, the energy distributions of electrons ejected into specific angular regions have been measured. Ar LMM satellite Auger electrons appear as a peak in the energy spectrum of electrons ejected at all large angles. The center of this peak is found at an electron energy of ∼179 eV. Electrons with ∼179 eV energy, ejected at large angles, are preferentially produced in coincidence with recoil ions of charge state 4+. Electrons with ∼345 eV energy and ∼505 eV energy ejected at large angles are preferentially produced in coincidence with recoil ions of charge state 3+. The angular distributions for these electrons are strongly peaked in the forward direction; essentially no electrons are observed at angles larger than 90 degree. These results are consistent with the dominant production mechanism for energetic electrons ejected at large angles being a binary-encounter process. Differential cross sections have been calculated from these angular distributions. They are on the order of 10 -21 cm 2 /(eV sr)

  18. GEM - The Global Earthquake Model

    Science.gov (United States)

    Smolka, A.

    2009-04-01

    Over 500,000 people died in the last decade due to earthquakes and tsunamis, mostly in the developing world, where the risk is increasing due to rapid population growth. In many seismic regions, no hazard and risk models exist, and even where models do exist, they are intelligible only by experts, or available only for commercial purposes. The Global Earthquake Model (GEM) answers the need for an openly accessible risk management tool. GEM is an internationally sanctioned public private partnership initiated by the Organisation for Economic Cooperation and Development (OECD) which will establish an authoritative standard for calculating and communicating earthquake hazard and risk, and will be designed to serve as the critical instrument to support decisions and actions that reduce earthquake losses worldwide. GEM will integrate developments on the forefront of scientific and engineering knowledge of earthquakes, at global, regional and local scale. The work is organized in three modules: hazard, risk, and socio-economic impact. The hazard module calculates probabilities of earthquake occurrence and resulting shaking at any given location. The risk module calculates fatalities, injuries, and damage based on expected shaking, building vulnerability, and the distribution of population and of exposed values and facilities. The socio-economic impact module delivers tools for making educated decisions to mitigate and manage risk. GEM will be a versatile online tool, with open source code and a map-based graphical interface. The underlying data will be open wherever possible, and its modular input and output will be adapted to multiple user groups: scientists and engineers, risk managers and decision makers in the public and private sectors, and the public-at- large. GEM will be the first global model for seismic risk assessment at a national and regional scale, and aims to achieve broad scientific participation and independence. Its development will occur in a

  19. A GEM Detector System for an Upgrade of the High-eta Muon Endcap Stations GE1/1 + ME1/1 in CMS

    CERN Document Server

    Abbaneo, D; Aspell, P.; Bianco, S.; Hoepfner, K.; Hohlmann, M.; Maggi, M.; De Lentdecker, G.; Safonov, A.; Sharma, A.; Tytgat, M.

    2012-01-01

    Based on the CMS Upgrade R&D Proposal RD10.02, we describe the motivation and main features of the CMS GEM Project for LS2 and propose the addition of a full GE1/12 detector station comprising Gas Electron Multiplier (GEM) chambers to the forward muon system of CMS. The limitations of the currently existing forward muon detector when operating at increasingly high luminosity expected after LS1 are laid out followed by a brief description of the anticipated performance improvements achievable with a GE1/1 station. The second part describes the detector system followed by an overview of electronics and associated services including a discussion of the schedule and cost of the project. Plans for a precursor demonstrator installation in LS1 are presented. This proposal is intended as a concise follow-up of the detailed document CMS-IN-2012-023. If approved, this is to be followed by a detailed Technical Design Report.

  20. Optical studies of multiply excited states

    International Nuclear Information System (INIS)

    Mannervik, S.

    1989-01-01

    Optical studies of multiply-excited states are reviewed with emphasis on emission spectroscopy. From optical measurements, properties such as excitation energies, lifetimes and autoionization widths can be determined with high accuracy, which constitutes a challenge for modern computational methods. This article mainly covers work on two-, three- and four-electron systems, but also sodium-like quartet systems. Furthermore, some comments are given on bound multiply-excited states in negative ions. Fine structure effects on transition wavelengths and lifetimes (autoionization) are discussed. In particular, the most recent experimental and theoretical studies of multiply-excited states are covered. Some remaining problems, which require further attention, are discussed in more detail. (orig.) With 228 refs

  1. The GEM detectors for the innermost region of the forward muon station of the LHCb experiment

    CERN Document Server

    Alfonsi, M

    The LHCb experiment will take place at the LHC accelerator at CERN and will start in 2008. It is dedicated to precision measurements of CP violation and rare decays in the b quark sec- tor. The apparatus is a single arm spectrometer and it is designed with a robust and flexible trigger in order to extensively gain access to a wide spread of differ ent physical processes involving beauty particles. This will allow to over-constrain the Standard M odel predictions about CP violation, and to discover any possible inconsistency, whi ch would reveal the presence of “New Physics” beyond the Standard Model. This thesis reports the work performed on two aspects of the L HCb experiment: the main contribution is the development and the construction of a de tector based on Gas Electron Multiplier (GEM) technology for the instrumentation of the high irradiated region around the beam pipe of the forward Muon Station; in the second part t he possibility of the search of the rare D 0 → + − decay at the LHCb exper...

  2. A dynamic method for charging-up calculations: the case of GEM

    International Nuclear Information System (INIS)

    Correia, P M M; Oliveira, C A B; Azevedo, C D R; Silva, A L M; Veloso, J F C A; Veenhof, R; Nemallapudi, M Varun

    2014-01-01

    The simulation of Micro Pattern Gaseous Detectors (MPGDs) signal response is an important and powerful tool for the design and optimization of such detectors. However, several attempts to exactly simulate the effective gas gain have not been completely successful. Namely, the gain stability over time has not been fully understood. Charging-up of the insulator surfaces have been pointed as one of the responsible for the difference between experimental and Monte Carlo results. This work describes two iterative methods to simulate the charging-up in one MPGD device, the Gas Electron Multiplier (GEM). The first method, which uses a constant step size for avalanches time evolution, is very detailed but slow to compute. The second method instead uses a dynamic step-size that improves the computing time. Good agreement between both methods was achieved. Comparison with experimental results shows that charging-up plays an important role in detectors operation, explaining the time evolution of the gain. However it doesn't seem to be the only responsible for the difference between measurements and Monte Carlo simulations

  3. Energy calibration of a GEM-TPC with Kr83m

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Roman [Helmholtz-Institut fuer Strahlen- und Kernphysik, Universitaet Bonn (Germany); Collaboration: GEM-TPC-Collaboration

    2013-07-01

    A Time Projection Chamber (TPC) with Gas Electron Multiplier (GEM) readout has been developed with an inner/outer radius of 5/15 cm and a total drift length of 73 cm. It has been used as an inner tracking upgrade for the FOPI experiment at GSI and is planned as a future upgrade to the CBELSA/TAPS experiment. A radioactive {sup 83m}Kr source has been produced and integrated into the setup in order to perform an accurate channel-wise relative gain calibration and monitor gain stability to achieve optimal dE/dx resolution. Its gaseous form makes it perfectly suitable for this purpose allowing a full coverage of the readout plane and providing a wide energy range of conversion peaks. Also its half-life of 1.83 h allows for normal detector operation after a short flushing period of several hours. Calibration method and measured energy resolution for different gas mixtures which have been compared to simulation results are presented in this talk. Also first results on gain stability and pressure/temperature-dependence are shown.

  4. Study of reconstruction methods for a time projection chamber with GEM gas amplification system

    Energy Technology Data Exchange (ETDEWEB)

    Diener, R.

    2006-12-15

    A new e{sup +}e{sup -} linear collider with an energy range up to 1TeV is planned in an international collaboration: the International Linear Collider (ILC). This collider will be able to do precision measurements of the Higgs particle and of physics beyond the Standard Model. In the Large Detector Concept (LDC) - which is one proposal for a detector at the ILC - a Time Projection Chamber (TPC) is foreseen as the main tracking device. To meet the requirements on the resolution and to be able to work in the environment at the ILC, the application of new gas amplification technologies in the TPC is necessary. One option is an amplification system based on Gas Electron Multipliers (GEMs). Due to the - in comparison with older technologies - small spatial width of the signals, this technology poses new requirements on the readout structures and the reconstruction methods. In this work, the performance and the systematics of different reconstruction methods have been studied, based on data measured with a TPC prototype in high magnetic fields of up to 4T and data from a Monte Carlo simulation. The latest results of the achievable point resolution are presented and their limitations have been investigated. (orig.)

  5. Study of reconstruction methods for a time projection chamber with GEM gas amplification system

    International Nuclear Information System (INIS)

    Diener, R.

    2006-12-01

    A new e + e - linear collider with an energy range up to 1TeV is planned in an international collaboration: the International Linear Collider (ILC). This collider will be able to do precision measurements of the Higgs particle and of physics beyond the Standard Model. In the Large Detector Concept (LDC) - which is one proposal for a detector at the ILC - a Time Projection Chamber (TPC) is foreseen as the main tracking device. To meet the requirements on the resolution and to be able to work in the environment at the ILC, the application of new gas amplification technologies in the TPC is necessary. One option is an amplification system based on Gas Electron Multipliers (GEMs). Due to the - in comparison with older technologies - small spatial width of the signals, this technology poses new requirements on the readout structures and the reconstruction methods. In this work, the performance and the systematics of different reconstruction methods have been studied, based on data measured with a TPC prototype in high magnetic fields of up to 4T and data from a Monte Carlo simulation. The latest results of the achievable point resolution are presented and their limitations have been investigated. (orig.)

  6. Electron-impact excitation of multiply-charged ions using energy loss in merged beams: e + Si3+(3s2S1/2) → e + Si3+(3p2P1/2,3/2)

    International Nuclear Information System (INIS)

    Wahlin, E.K.; Thompson, J.S.; Dunn, G.H.; Phaneuf, R.A.; Gregory, D.C.; Smith, A.C.H.

    1990-01-01

    For the first time absolute total cross sections for electron-impact excitation of a multiply-charged ion have been measured using an electron-energy-loss technique. Measurements were made near threshold for the process e + Si 3+ (3s 2 S 1/2 ) → e + Si 3+ (3p 2 P 1/2 , 3/2 ) -- 8.88 eV. The 10 -15 cm 2 measured cross section agrees with results of 7-state close coupling calculations to better than the ±20% (90% CL) total uncertainty of the measurements. Convoluting the theoretical curve with a Gaussian energy distribution indicates an energy width of 0.15 approx-lt ΔE approx-lt 0.20 eV. 12 refs., 2 figs

  7. The Forward GEM Tracker of STAR at RHIC

    OpenAIRE

    Simon, F.; Balewski, J.; Fatemi, R.; Hasell, D.; Kelsey, J.; Majka, R.; Page, B.; Plesko, M.; Underwood, D.; Smirnov, N.; Sowinski, J.; Spinka, H.; Surrow, B.; Visser, G.

    2008-01-01

    The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) is in the process of designing and constructing a forward tracking system based on triple GEM technology. This upgrade is necessary to give STAR the capability to reconstruct and identify the charge sign of W bosons over an extended rapidity range through their leptonic decay mode into an electron (positron) and a neutrino. This will allow a detailed study of the flavor-separated spin str...

  8. GPU Computing Gems Emerald Edition

    CERN Document Server

    Hwu, Wen-mei W

    2011-01-01

    ".the perfect companion to Programming Massively Parallel Processors by Hwu & Kirk." -Nicolas Pinto, Research Scientist at Harvard & MIT, NVIDIA Fellow 2009-2010 Graphics processing units (GPUs) can do much more than render graphics. Scientists and researchers increasingly look to GPUs to improve the efficiency and performance of computationally-intensive experiments across a range of disciplines. GPU Computing Gems: Emerald Edition brings their techniques to you, showcasing GPU-based solutions including: Black hole simulations with CUDA GPU-accelerated computation and interactive display of

  9. ROLE OF GEMS IN INDIAN MEDICINE

    Science.gov (United States)

    Murthy, S.R.N.

    1991-01-01

    This paper is the first attempt in introducing the medicinal importance of gems as found in the Sanskrit text ‘Rasaratnasamuccaya’, which has been rendered an English translation here. The modern physicians and gemologists will find this study quite useful in continuing research and, thus, develop a new field of gem medicine. PMID:22556526

  10. UWB delay and multiply receiver

    Energy Technology Data Exchange (ETDEWEB)

    Dallum, Gregory E.; Pratt, Garth C.; Haugen, Peter C.; Romero, Carlos E.

    2013-09-10

    An ultra-wideband (UWB) delay and multiply receiver is formed of a receive antenna; a variable gain attenuator connected to the receive antenna; a signal splitter connected to the variable gain attenuator; a multiplier having one input connected to an undelayed signal from the signal splitter and another input connected to a delayed signal from the signal splitter, the delay between the splitter signals being equal to the spacing between pulses from a transmitter whose pulses are being received by the receive antenna; a peak detection circuit connected to the output of the multiplier and connected to the variable gain attenuator to control the variable gain attenuator to maintain a constant amplitude output from the multiplier; and a digital output circuit connected to the output of the multiplier.

  11. The CLIC Test Facility (CTF3) which allowed the first electron beam recombination in order to multiply the RF frequency from 3 GHz up to 15 GHz.

    CERN Multimedia

    Maximilien Brice

    2002-01-01

    Photo 0210005_11: The CTF3 linac accelerates an electron beam up to 350 MeV. Photo 0210005_1: At the front, the yellow dipole is used for the spectrometer line. At the back, a doublet of blue quadrupole for the matching. Photo 0210005_03: The CTF3 transfer line between the electron linac and the isochronous ring. Photo 0210005_04: One arc of the EPA isochronous ring. Photo 0210005_06: The CTF3 bunching system. The first RF wave guide feeds the Pre-Buncher while the second RF wave guide feeds the Buncher. They provide a bunched electron beam at 4 MeV. The blue magnet is a solenoid around the Buncher. Photo 0210005_07: A LIL accelerating structure used for CTF3. It is 4.5 meters long and provides an energy gain of 45 MeV. One can see 3 quadrupoles around the RF structure.

  12. Serial data acquisition for the X-ray plasma diagnostics with selected GEM detector structures

    International Nuclear Information System (INIS)

    Czarski, T.; Chernyshova, M.; Pozniak, K.T.; Kasprowicz, G.; Zabolotny, W.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zienkiewicz, P.

    2015-01-01

    The measurement system based on GEM—Gas Electron Multiplier detector is developed for X-ray diagnostics of magnetic confinement tokamak plasmas. The paper is focused on the measurement subject and describes the fundamental data processing to obtain reliable characteristics (histograms) useful for physicists. The required data processing have two steps: 1—processing in the time domain, i.e. events selections for bunches of coinciding clusters, 2—processing in the planar space domain, i.e. cluster identification for the given detector structure. So, it is the software part of the project between the electronic hardware and physics applications. The whole project is original and it was developed by the paper authors. The previous version based on 1-D GEM detector was applied for the high-resolution X-ray crystal spectrometer KX1 in the JET tokamak. The current version considers 2-D detector structures for the new data acquisition system. The fast and accurate mode of data acquisition implemented in the hardware in real time can be applied for the dynamic plasma diagnostics. Several detector structures with single-pixel sensors and multi-pixel (directional) sensors are considered for two-dimensional X-ray imaging. Final data processing is presented by histograms for selected range of position, time interval and cluster charge values. Exemplary radiation source properties are measured by the basic cumulative characteristics: the cluster position distribution and cluster charge value distribution corresponding to the energy spectra. A shorter version of this contribution is due to be published in PoS at: 1 st EPS conference on Plasma Diagnostics

  13. Serial data acquisition for the X-ray plasma diagnostics with selected GEM detector structures

    Science.gov (United States)

    Czarski, T.; Chernyshova, M.; Pozniak, K. T.; Kasprowicz, G.; Zabolotny, W.; Kolasinski, P.; Krawczyk, R.; Wojenski, A.; Zienkiewicz, P.

    2015-10-01

    The measurement system based on GEM—Gas Electron Multiplier detector is developed for X-ray diagnostics of magnetic confinement tokamak plasmas. The paper is focused on the measurement subject and describes the fundamental data processing to obtain reliable characteristics (histograms) useful for physicists. The required data processing have two steps: 1—processing in the time domain, i.e. events selections for bunches of coinciding clusters, 2—processing in the planar space domain, i.e. cluster identification for the given detector structure. So, it is the software part of the project between the electronic hardware and physics applications. The whole project is original and it was developed by the paper authors. The previous version based on 1-D GEM detector was applied for the high-resolution X-ray crystal spectrometer KX1 in the JET tokamak. The current version considers 2-D detector structures for the new data acquisition system. The fast and accurate mode of data acquisition implemented in the hardware in real time can be applied for the dynamic plasma diagnostics. Several detector structures with single-pixel sensors and multi-pixel (directional) sensors are considered for two-dimensional X-ray imaging. Final data processing is presented by histograms for selected range of position, time interval and cluster charge values. Exemplary radiation source properties are measured by the basic cumulative characteristics: the cluster position distribution and cluster charge value distribution corresponding to the energy spectra. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  14. Effective switching frequency multiplier inverter

    Science.gov (United States)

    Su, Gui-Jia [Oak Ridge, TN; Peng, Fang Z [Okemos, MI

    2007-08-07

    A switching frequency multiplier inverter for low inductance machines that uses parallel connection of switches and each switch is independently controlled according to a pulse width modulation scheme. The effective switching frequency is multiplied by the number of switches connected in parallel while each individual switch operates within its limit of switching frequency. This technique can also be used for other power converters such as DC/DC, AC/DC converters.

  15. Gender Evaluation Methodology (GEM) | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2011-10-28

    Oct 28, 2011 ... For more resources and access to the GEM Practitioners Network, ... Home · Resources · Publications ... The Association for Progressive Communications Women's Networking Support Programme (APC WNSP) developed ...

  16. GEM Building Taxonomy (Version 2.0)

    Science.gov (United States)

    Brzev, S.; Scawthorn, C.; Charleson, A.W.; Allen, L.; Greene, M.; Jaiswal, Kishor; Silva, V.

    2013-01-01

    This report documents the development and applications of the Building Taxonomy for the Global Earthquake Model (GEM). The purpose of the GEM Building Taxonomy is to describe and classify buildings in a uniform manner as a key step towards assessing their seismic risk, Criteria for development of the GEM Building Taxonomy were that the Taxonomy be relevant to seismic performance of different construction types; be comprehensive yet simple; be collapsible; adhere to principles that are familiar to the range of users; and ultimately be extensible to non-buildings and other hazards. The taxonomy was developed in conjunction with other GEM researchers and builds on the knowledge base from other taxonomies, including the EERI and IAEE World Housing Encyclopedia, PAGER-STR, and HAZUS. The taxonomy is organized as a series of expandable tables, which contain information pertaining to various building attributes. Each attribute describes a specific characteristic of an individual building or a class of buildings that could potentially affect their seismic performance. The following 13 attributes have been included in the GEM Building Taxonomy Version 2.0 (v2.0): 1.) direction, 2.)material of the lateral load-resisting system, 3.) lateral load-resisting system, 4.) height, 5.) date of construction of retrofit, 6.) occupancy, 7.) building position within a block, 8.) shape of the building plan, 9.) structural irregularity, 10.) exterior walls, 11.) roof, 12.) floor, 13.) foundation system. The report illustrates the pratical use of the GEM Building Taxonomy by discussing example case studies, in which the building-specific characteristics are mapped directly using GEM taxonomic attributes and the corresponding taxonomic string is constructed for that building, with "/" slash marks separating attributes. For example, for the building shown to the right, the GEM Taxonomy string is: DX1/MUR+CLBRS+MOCL2/LWAL3/

  17. Measurements of ion mobility and GEM discharge studies for the upgrade of the ALICE time projection chamber

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00507268

    2018-02-20

    ALICE is one of the four experiments at the Large Hadron Collider (LHC). The quark-gluon plasma, which is predominantly produced in lead-lead collisions at LHC, is of particular interest for ALICE. After the long shut-down 2 (2019-2021) the LHC will provide lead-lead collisions at an increased interaction rate of 50 kHz. In order to examine every event at this interaction rate the ALICE Time Projection Chamber (TPC) needs to be upgraded. The TPC’s ReadOut Chambers (ROCs) are currently multi-wire proportional chambers. To prevent space charge build-up of slow ions, drifting from the ROCs into the TPC, a gating grid is used. The corresponding closure time imposes a dead time on the TPC read out, which prohibits data taking at a readout rate higher than 3 kHz. New ROCs have therefore been designed, relying on stacks of Gas Electron Multiplier (GEM) foils for the gas amplification, allowing for continuous readout. With the new ROCs, a certain fraction of ions will be drifting at all time into the TPC. Knowing t...

  18. arXiv Particle identification studies with a full-size 4-GEM prototype for the ALICE TPC upgrade

    CERN Document Server

    INSPIRE-00180720; Aiola, S.; Alme, J.; Alt, T.; Amend, W.; Andronic, A.; Anguelov, V.; Appelshäuser, H.; Arslandok, M.; Averbeck, R.; Ball, M.; Barnaföldi, G.G.; Bartsch, E.; Bellwied, R.; Bencedi, G.; Berger, M.; Bialas, N.; Bialas, P.; Bianchi, L.; Biswas, S.; Boldizsár, L.; Bratrud, L.; Braun-Munzinger, P.; Bregant, M.; Britton, C.L.; Brucken, E.J.; Caines, H.; Castro, A.J.; Chattopadhyay, S.; Christiansen, P.; Clonts, L.G.; Cormier, T.M.; Das, S.; Dash, S.; Deisting, A.; Dittrich, S.; Dubey, A.K.; Ehlers, R.; Erhardt, F.; Ezell, N.B.; Fabbietti, L.; Frankenfeld, U.; Gaardhøje, J.J.; Garabatos, C.; Gasik, P.; Gera, A.; Ghosh, P.; Ghosh, S.K.; Glässel, P.; Grachov, O.; Grein, A.; Gunji, T.; Hamagaki, H.; Hamar, G.; Harris, J.W.; Hehner, J.; Hellbär, E.; Helstrup, H.; Hilden, T.E.; Hohlweger, B.; Ivanov, M.; Jung, M.; Just, D.; Kangasaho, E.; Keidel, R.; Ketzer, B.; Khan, S.A.; Kirsch, S.; Klemenz, T.; Klewin, S.; Knospe, A.G.; Kowalski, M.; Kumar, L.; Lang, R.; Langoy, R.; Lautner, L.; Liebske, F.; Lien, J.; Lippmann, C.; Ljunggren, H.M.; Llope, W.J.; Mahmood, S.; Mahmoud, T.; Majka, R.; Malzacher, P.; Marín, A.; Markert, C.; Masciocchi, S.; Mathis, A.; Matyja, A.; Meres, M.; Mihaylov, D.L.; Miskowiec, D.; Mitra, J.; Mittelstaedt, T.; Morhardt, T.; Mulligan, J.; Munzer, R.H.; Münning, K.; Munhoz, M.G.; Muhuri, S.; Murakami, H.; Nandi, B.K.; Natal da Luz, H.; Nattrass, C.; Nayak, T.K.; Negrao De Oliveira, R.A.; Nicassio, M.; Nielsen, B.S.; Oláh, L.; Oskarsson, A.; Otwinowski, J.; Oyama, K.; Paić, G.; Patra, R.N.; Peskov, V.; Pikna, M.; Pinsky, L.; Planinic, M.; Poghosyan, M.G.; Poljak, N.; Pompei, F.; Prasad, S.K.; Pruneau, C.A.; Putschke, J.; Raha, S.; Rak, J.; Rasson, J.; Ratza, V.; Read, K.F.; Rehman, A.; Renfordt, R.; Richert, T.; Røed, K.; Röhrich, D.; Rudzki, T.; Sahoo, R.; Sahoo, S.; Sahu, P.K.; Saini, J.; Schaefer, B.; Schambach, J.; Scheid, S.; Schmidt, C.; Schmidt, H.R.; V Schmidt, N.; Schulte, H.; Schweda, K.; Selyuzhenkov, I.; Sharma, N.; Silvermyr, D.; Singaraju, R.N.; Sitar, B.; Smirnov, N.; Sorensen, S.P.; Sozzi, F.; Stachel, J.; Stenlund, E.; Strmen, P.; Szarka, I.; Tambave, G.; Terasaki, K.; Timmins, A.; Ullaland, K.; Utrobicic, A.; Varga, D.; Varma, R.; Velure, A.; Vislavicius, V.; Voloshin, S.; Voss, B.; Vranic, D.; Wiechula, J.; Winkler, S.; Wikne, J.; Windelband, B.; Zhao, C.

    A large Time Projection Chamber is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019/20, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 50 above the present readout rate of the TPC. This will result in a significant improvement on the sensitivity to rare probes that are considered key observables to characterize the QCD matter created in such collisions. In order to make full use of this luminosity, the currently used gated Multi-Wire Proportional Chambers will be replaced. The upgrade relies on continuously operated readout detectors employing Gas Electron Multiplier technology to retain the performance in terms of particle identification via the measurement of the specific energy loss by ionization d$E$/d$x$. A full-size readout chamber prototype was assembled in 2014 featuring a stack of four GEM foils as an amplification stage. The performance of the pr...

  19. A Synthesis of Star Calibration Techniques for Ground-Based Narrowband Electron-Multiplying Charge-Coupled Device Imagers Used in Auroral Photometry

    Science.gov (United States)

    Grubbs, Guy II; Michell, Robert; Samara, Marilia; Hampton, Don; Jahn, Jorg-Micha

    2016-01-01

    A technique is presented for the periodic and systematic calibration of ground-based optical imagers. It is important to have a common system of units (Rayleighs or photon flux) for cross comparison as well as self-comparison over time. With the advancement in technology, the sensitivity of these imagers has improved so that stars can be used for more precise calibration. Background subtraction, flat fielding, star mapping, and other common techniques are combined in deriving a calibration technique appropriate for a variety of ground-based imager installations. Spectral (4278, 5577, and 8446 A ) ground-based imager data with multiple fields of view (19, 47, and 180 deg) are processed and calibrated using the techniques developed. The calibration techniques applied result in intensity measurements in agreement between different imagers using identical spectral filtering, and the intensity at each wavelength observed is within the expected range of auroral measurements. The application of these star calibration techniques, which convert raw imager counts into units of photon flux, makes it possible to do quantitative photometry. The computed photon fluxes, in units of Rayleighs, can be used for the absolute photometry between instruments or as input parameters for auroral electron transport models.

  20. Lagrange multipliers and gravitational theory

    International Nuclear Information System (INIS)

    Elston, F.D.

    1977-01-01

    The Lagrange multiplier variational method is extended to nonlinear Lagrangians in a Riemann space, where it is shown explicitly for the quadratic Lagrangians that, as expected, this approach is equivalent to the Hilbert variational method. It is not, in general, equivalent to the Palatini variational method. The nonvanishing Lagrange multipliers for the quadratic Lagrangians are explicitly obtained in covariant form. A similiar analysis is then carried out in a Riemann--Cartan torsional metric space for the specific Lagrangians g/sup 1/2/R tilde and g/sup 1/2/R/sub uv/tilde R/sup uv/tilde. The possible relevance of the R/sub uv/R/sup u anti v/ invariant to an action-principle formulation of the Rainich--Misner--Wheeler (RMW) already-unified theory is also discussed. It is then pointed out how a different use of the Lagrange multiplier technique in the language of the 3 + 1 canonical formalism developed by Arnowitt, Deser, and Misner (ADM) permits the recasting of the equations of motion for quadratic and general higher-order invariants into the ADM canonical formalism. In general, without this Lagrange multiplier approach, the higher-order ADM problem could not be solved. This is done explicitly for the simplest quadratic Langrangian g/sup 1/2/R 2 as an example

  1. Multiplied Environmental Literacy. Final Report.

    Science.gov (United States)

    Buethe, Chris

    This booklet presents a pupil-oriented program designed to increase the environmental literacy of teachers and students in Indiana schools through a programmed multiplier effect. Junior and senior high school science teachers were prepared to teach students the meanings of 44 selected environmental terms and related concepts. Those teachers then…

  2. The GEM Detector projective alignment simulation system

    International Nuclear Information System (INIS)

    Wuest, C.R.; Belser, F.C.; Holdener, F.R.; Roeben, M.D.; Paradiso, J.A.; Mitselmakher, G.; Ostapchuk, A.; Pier-Amory, J.

    1993-01-01

    Precision position knowledge (< 25 microns RMS) of the GEM Detector muon system at the Superconducting Super Collider Laboratory (SSCL) is an important physics requirement necessary to minimize sagitta error in detecting and tracking high energy muons that are deflected by the magnetic field within the GEM Detector. To validate the concept of the sagitta correction function determined by projective alignment of the muon detectors (Cathode Strip Chambers or CSCs), the basis of the proposed GEM alignment scheme, a facility, called the ''Alignment Test Stand'' (ATS), is being constructed. This system simulates the environment that the CSCs and chamber alignment systems are expected to experience in the GEM Detector, albeit without the 0.8 T magnetic field and radiation environment. The ATS experimental program will allow systematic study and characterization of the projective alignment approach, as well as general mechanical engineering of muon chamber mounting concepts, positioning systems and study of the mechanical behavior of the proposed 6 layer CSCs. The ATS will consist of a stable local coordinate system in which mock-ups of muon chambers (i.e., non-working mechanical analogs, representing the three superlayers of a selected barrel and endcap alignment tower) are implemented, together with a sufficient number of alignment monitors to overdetermine the sagitta correction function, providing a self-consistency check. This paper describes the approach to be used for the alignment of the GEM muon system, the design of the ATS, and the experiments to be conducted using the ATS

  3. Study of gain variation as a function of physical parameters of GEM foil

    CERN Document Server

    Das, Supriya

    2015-01-01

    The ALICE experiment at LHC has planned to upgrade the TPC by replacing the MWPC with GEM based detecting elements to restrict the IBF to a tolerable value. However the variation of the gain as a function of physical parameters of industrially produced large size GEM foils is needed to be studied as a part of the QA procedure for the detector. The size of the electron avalanche and consequently the gain for GEM based detectors depend on the electric field distribution inside the holes. Geometry of a hole plays an important role in defining the electric field inside it. In this work we have studied the variation of the gain as a function of the hole diameters using Garfield++ simulation package.

  4. Principal parameters of classical multiply charged ion sources

    International Nuclear Information System (INIS)

    Winter, H.; Wolf, B.H.

    1974-01-01

    A review is given of the operational principles of classical multiply charged ion sources (operating sources for intense beams of multiply charged ions using discharge plasmas; MCIS). The fractional rates of creation of multiply charged ions in MCIS plasmas cannot be deduced from the discharge parameters in a simple manner; they depend essentially on three principal parameters, the density and energy distribution of the ionizing electrons, and the confinement time of ions in the ionization space. Simple discharge models were used to find relations between principal parameters, and results of model calculations are compared to actually measured charge state density distributions of extracted ions. Details of processes which determine the energy distribution of ionizing electrons (heating effects), confinement times of ions (instabilities), and some technical aspects of classical MCIS (cathodes, surface processes, conditioning, life time) are discussed

  5. For fashion and health (coloring of gems)

    International Nuclear Information System (INIS)

    Umeda, Iwao

    1998-01-01

    Artificial coloration of colorless jewel grade diamonds can be made by fast neutron irradiation using a research reactor or high energy electron beam bombardment by a linear accelerator. The irradiated color diamonds are from blue to green. After irradiation, the blue-green diamonds change color to yellow or orange by subsequent annealing using an electric furnace. The colored diamond hue depends on the treatment conditions. Fancy hue can be produced under some suitable conditions. Some special absorption bands in the spectrum obtained by a spectrophotometer can discriminate artificially colored diamonds from natural fancy color diamonds. Diamonds become to be radioactive immediately after irradiation by a reactor, but the radioactivity decay rapidly and become safe after a month. Some imported gems without diamond as blue topaz etc. are sometimes discovered to be radioactive artificially. Cultured pearls are covered by 0.4 mm thick nacreous layer on the pearl nucleus made of fresh-water unionidae thick shell. White pearls turn color to silver by 60 Co γ-ray irradiation. The pearl nucleus contained Mn turns color to brown by irradiation and absorbs red light from reflection on the surface, whereas the nacreous layer is little color change by irradiation because of small quantity of Mn and remains the luster. White pearls turn beautiful blue-silver of like natural color pearls seemingly, by γ-ray irradiation in suitable solution. Cubic zirconia made from ZrO 2 is a man-made colorless crystal looked like a diamond. The crystals turn color to orange by irradiation. (J.P.N)

  6. GEM gas detectors for soft X-ray imaging in fusion devices with neutron–gamma background

    Energy Technology Data Exchange (ETDEWEB)

    Pacella, Danilo, E-mail: danilo.pacella@enea.it [Associazione EURATOM-ENEA, C.R. Frascati, Via E. Fermi 45, 00044 Frascati, Roma (Italy); Romano, Afra; Gabellieri, Lori [Associazione EURATOM-ENEA, C.R. Frascati, Via E. Fermi 45, 00044 Frascati, Roma (Italy); Murtas, Fabrizio [Istituto Nazionale di Fisica Nucleare, Via E. Fermi 45, 00044 Frascati, Roma (Italy); Mazon, Didier [Association EURATOM-CEA, CEA Cadarache, DSM/IRFM, 13108 St. Paul Lez Durance Cedex (France)

    2013-08-21

    A triple gas electron multiplier (GEM) detector has been built and characterized in a collaboration between ENEA, INFN and CEA to develop a soft X-ray imaging diagnostic for magnetic fusion plasmas. It has an active area of 5×5 cm{sup 2}, 128 pixels and electronics in counting mode. Since burning plasma experiments will have a very large background of radiation, this prototype has been tested with contemporary X-ray, neutron and gamma irradiation, to study the detection efficiencies, and the discrimination capabilities. The detector has been preliminarily characterized under DD neutron irradiation (2.45 MeV) up to 2.2×10{sup 6} n/s on the detector active area, showing a detection efficiency of about 10{sup −4}, while the detection efficiency of X-rays is more than three orders of magnitude higher. The detector has been also tested under DT neutron flux (14 MeV) up to 2.8×10{sup 8} n/s on the whole detector, with a detection efficiency of about 10{sup −5}. The calibration of the γ-rays detection has been done by means of a source of {sup 60}Co (gamma rays of energy 1.17 MeV and 1.33 MeV) and the detection efficiency was found of the order of 10{sup −4}. Thanks to the adjustable gain of the detector and the discrimination threshold of the electronics, it is possible to minimize the sensitivity to neutrons and gamma, and discriminate the X-ray signals even with very high radiative background.

  7. Neutron beam imaging with GEM detectors

    International Nuclear Information System (INIS)

    Albani, G.; Cazzaniga, C.; Rebai, M.; Gorini, G.; Croci, G.; Muraro, A.; Cippo, E. Perelli; Tardocchi, M.; Cavenago, M.; Murtas, F.; Claps, G.; Pasqualotto, R.

    2015-01-01

    Neutron GEM-based detectors represent a new frontier of devices in neutron physics applications where a very high neutron flux must be measured such as future fusion experiments (e.g. ITER Neutral beam Injector) and spallation sources (e.g. the European Spallation source). This kind of detectors can be properly adapted to be used both as beam monitors but also as neutron diffraction detectors that could represent a valid alternative for the 3 He detectors replacement. Fast neutron GEM detectors (nGEM) feature a cathode composed by one layer of polyethylene and one of aluminium (neutron scattering on hydrogen generates protons that are detected in the gas) while thermal neutron GEM detectors (bGEM) are equipped with a borated aluminium cathode (charged particles are generated through the 10 B(n,α) 7 Li reaction). GEM detectors can be realized in large area (1 m 2 ) and their readout can be pixelated. Three different prototypes of nGEM and one prototype of bGEM detectors of different areas and equipped with different types of readout have been built and tested. All the detectors have been used to measure the fast and thermal neutron 2D beam image at the ISIS-VESUVIO beamline. The different kinds of readout patterns (different areas of the pixels) have been compared in similar conditions. All the detectors measured a width of the beam profile consitent with the expected one. The imaging property of each detector was then tested by inserting samples of different material and shape in the beam. All the samples were correctly reconstructed and the definition of the reconstruction depends on the type of readout anode. The fast neutron beam profile reconstruction was then compared to the one obtained by diamond detectors positioned on the same beamline while the thermal neutron one was compared to the imaged obtained by cadmium-coupled x-rays films. Also efficiency and the gamma background rejection have been determined. These prototypes represent the first step towards

  8. Gravity model improvement using GEOS-3 (GEM 9 and 10)

    Science.gov (United States)

    Lerch, F. J.; Klosko, S. M.; Laubscher, R. E.; Wagner, C. A.

    1977-01-01

    The use of collocation permitted GEM 9 to be a larger field than previous derived satellite models, GEM 9 having harmonics complete to 20 x 20 with selected higher degree terms. The satellite data set has approximately 840,000 observations, of which 200,000 are laser ranges taken on 9 satellites equipped with retroreflectors. GEM 10 is complete to 22 x 22 with selected higher degree terms out to degree and order 30 amounting to a total of 592 coefficients. Comparisons with surface gravity and altimeter data indicate a substantial improvement in GEM 9 over previous satellite solutions; GEM 9 is in even closer agreement with surface data than the previously published GEM 6 solution which contained surface gravity. In particular the free air gravity anomalies calculated from GEM 9 and a surface gravity solution are in excellent agreement for the high degree terms.

  9. Methods and results for calibration and track separation of a GEM based TPC using an UV-laser

    International Nuclear Information System (INIS)

    Ball, Markus

    2008-12-01

    In the last 30 years high energy physics could write an impressive story of success. Since the introduction of the Standard Model (SM), it has met every experimental test. However the final confirmation has to prove the mechanism of electroweak symmetry breaking, which could not be confirmed yet. The most favored theory, which includes the introduction of a Higgs field, could not be verified experimentally. Furthermore there is clear evidence, that the SM is only a low energy description of nature and its principles, as the SM describes only 4 % of the known matter in the universe. There are two different approaches in accelerator driven high energy physics to clarify the open questions. The Large Hadron Collider (LHC) have a good opportunity to measure some of the missing pieces with its high center of mass energy. The International Linear Collider (ILC) will then measure their parameters with high precision. To guarantee this high precision the detectors have to be able to identify every single particle and determine its properties with high accuracy. These high requirements to the single detectors as well as the interconnectivity between all detectors are summarised by the concept of particle flow (PFLOW). This means that all particles must be separable, which includes in particular the main tracking device. A possible candidate for the central tracking device is a Time Projection Chamber (TPC). In this work a TPC with Gas Electron Multipliers (GEM) as gas amplification system was used. The GEMs replace the conventional wire amplification system of the TPC. In this PhD work a method to determine the drift velocity of a TPC was developed and tested using an ultraviolet laser. To ensure a high accuracy of the method all relevant gas parameters were measured with a slow control system. Furthermore the laser was used to investigate the separation capability of nearby tracks. Therefore an existing TPC prototype, which was developed to operate in a 5 T magnet facility

  10. Methods and results for calibration and track separation of a GEM based TPC using an UV-laser

    Energy Technology Data Exchange (ETDEWEB)

    Ball, Markus

    2008-12-15

    In the last 30 years high energy physics could write an impressive story of success. Since the introduction of the Standard Model (SM), it has met every experimental test. However the final confirmation has to prove the mechanism of electroweak symmetry breaking, which could not be confirmed yet. The most favored theory, which includes the introduction of a Higgs field, could not be verified experimentally. Furthermore there is clear evidence, that the SM is only a low energy description of nature and its principles, as the SM describes only 4 % of the known matter in the universe. There are two different approaches in accelerator driven high energy physics to clarify the open questions. The Large Hadron Collider (LHC) have a good opportunity to measure some of the missing pieces with its high center of mass energy. The International Linear Collider (ILC) will then measure their parameters with high precision. To guarantee this high precision the detectors have to be able to identify every single particle and determine its properties with high accuracy. These high requirements to the single detectors as well as the interconnectivity between all detectors are summarised by the concept of particle flow (PFLOW). This means that all particles must be separable, which includes in particular the main tracking device. A possible candidate for the central tracking device is a Time Projection Chamber (TPC). In this work a TPC with Gas Electron Multipliers (GEM) as gas amplification system was used. The GEMs replace the conventional wire amplification system of the TPC. In this PhD work a method to determine the drift velocity of a TPC was developed and tested using an ultraviolet laser. To ensure a high accuracy of the method all relevant gas parameters were measured with a slow control system. Furthermore the laser was used to investigate the separation capability of nearby tracks. Therefore an existing TPC prototype, which was developed to operate in a 5 T magnet facility

  11. X-Ray Polarimetry with GEMS

    Science.gov (United States)

    Strohmayer, Tod

    2011-01-01

    The polarization properties of cosmic X-ray sources are still largely unexplored. The Gravity and Extreme Magnetism SMEX (GEMS) will carry out the first sensitive X-ray polarization survey of a wide range of sources including; accreting compact objects (black holes and neutron stars), AGN, supernova remnants, magnetars and rotation-powered pulsars. GEMS employs grazing-incidence foil mirrors and novel time-projection chamber (TPC) polarimeters leveraging the photoelectric effect to achieve high polarization sensitivity in the 2 - 10 keV band. I will provide an update of the project status, illustrate the expected performance with several science examples, and provide a brief overview of the data analysis challenges

  12. Gallium Electromagnetic (GEM) Thrustor Concept and Design

    Science.gov (United States)

    Polzin, Kurt A.; Markusic, Thomas E.

    2006-01-01

    We describe the design of a new type of two-stage pulsed electromagnetic accelerator, the gallium electromagnetic (GEM) thruster. A schematic illustration of the GEM thruster concept is given in Fig. 1. In this concept, liquid gallium propellant is pumped into the first stage through a porous metal electrode using an electromagneticpump[l]. At a designated time, a pulsed discharge (approx.10-50 J) is initiated in the first stage, ablating the liquid gallium from the porous electrode surface and ejecting a dense thermal gallium plasma into the second state. The presence of the gallium plasma in the second stage serves to trigger the high-energy (approx.500 I), send-stage puke which provides the primary electromagnetic (j x B) acceleration.

  13. Synthesis algorithm of VLSI multipliers for ASIC

    Science.gov (United States)

    Chua, O. H.; Eldin, A. G.

    1993-01-01

    Multipliers are critical sub-blocks in ASIC design, especially for digital signal processing and communications applications. A flexible multiplier synthesis tool is developed which is capable of generating multiplier blocks for word size in the range of 4 to 256 bits. A comparison of existing multiplier algorithms is made in terms of speed, silicon area, and suitability for automated synthesis and verification of its VLSI implementation. The algorithm divides the range of supported word sizes into sub-ranges and provides each sub-range with a specific multiplier architecture for optimal speed and area. The algorithm of the synthesis tool and the multiplier architectures are presented. Circuit implementation and the automated synthesis methodology are discussed.

  14. arXiv The new cylindrical GEM inner tracker of BESIII

    CERN Document Server

    Lavezzi, L.; Amoroso, A.; Ferroli, R. Baldini; Bertani, M.; Bettoni, D.; Bianchi, F.; Calcaterra, A.; Canale, N.; Capodiferro, M.; Carassiti, V.; Cerioni, S.; Chai, Jy; Chiozzi, S.; Cibinetto, G.; Cossio, F.; Cotta Ramusino, A.; De Mori, F.; Destefanis, M.; Dong, J.; Evangelisti, F.; Farinelli, R.; Fava, L.; Felici, G.; Fioravanti, E.; Garzia, I.; Gatta, M.; Greco, M.; Leng, Cy; Li, H.; Maggiora, M.; Malaguti, R.; Marcello, S.; Melchiorri, M.; Mezzadri, G.; Mignone, M.; Morello, G.; Pacetti, S.; Patteri, P.; Pellegrino, J.; Pelosi, A.; Rivetti, A.; Rolo,; Savrié, M.; Scodeggio, M.; Soldani, E.; Sosio, S.; Spataro, S.; Tskhadadze, E.; Verma, S.; Wheadon, R.; Yan, L.

    2018-05-03

    The Cylindrical GEM-Inner Tracker (CGEM-IT) is the upgrade of the internal tracking system of the BESIII experiment. It consists of three layers of cylindrically-shaped triple GEMs, with important innovations with respect to the existing GEM detectors, in order to achieve the best performance with the lowest material budget. It will be the first cylindrical GEM running with analog readout inside a 1T magnetic field. The simultaneous measurement of both the deposited charge and the signal time will permit to use a combination of two algorithms to evaluate the spatial position of the charged tracks inside the CGEM-IT: the charge centroid and the micro time projection chamber modes. They are complementary and can cope with the asymmetry of the electron avalanche when running in magnetic field and with non-orthogonal incident tracks. To evaluate the behaviour under different working settings, both planar chambers and the first cylindrical prototype have been tested during various test beams at CERN with 150 GeV/c...

  15. Energy resolution studies of an IROC GEM prototype for the ALICE TPC

    Energy Technology Data Exchange (ETDEWEB)

    Mathis, Andreas [TU Muenchen, Physik Department E12, Excellence Cluster ' ' Universe' ' , D-85748, Garching (Germany); Collaboration: ALICE-Collaboration

    2015-07-01

    The ALICE collaboration (A Large Ion Collider Experiment) is planning an upgrade of its central barrel detectors, to be able to cope with the increased LHC luminosity beyond 2018. In order to fully exploit the increase in collision rate to about 50 kHz in Pb-Pb, the TPC is foreseen to be operated in an ungated mode with continuous readout. This demands for a replacement of the currently used, gated MWPC by GEM-based readout chambers, while retaining the present tracking and particle identification capabilities of the TPC via measurement of the specific energy loss (dE/dx). The present baseline solution for the TPC upgrade consists of a stack of four large-sized GEM foils as amplification stage, containing both Standard (S, 140 μm) and Large Pitch (LP, 280 μm) GEM foils arranged in the order S-LP-LP-S. This arrangement has been proven as advantageous in terms of ion backflow and energy resolution. A prototype of an ALICE IROC (Inner Readout Chamber) was equipped with such a quadruple GEM stack, installed inside a field cage and exposed to a beam of electrons and pions from the CERN PS. The performance of the prototype in terms of energy resolution has been evaluated and is presented.

  16. Study of the spatial resolution of low-material GEM tracking detectors

    Directory of Open Access Journals (Sweden)

    Kudryavtsev V.N.

    2018-01-01

    Full Text Available The spatial resolution of GEM based tracking detectors has been simulated and measured. The simulation includes the GEANT4 based transport of high energy electrons with careful accounting for atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing, including accounting for diffusion, gas amplification fluctuations, the distribution of signals on readout electrodes, electronics noise and a particular algorithm of the final coordinate calculation (center of gravity. The simulation demonstrates that a minimum of the spatial resolution of about 10 μm can be achieved with strip pitches from 250 μm to 300 μm. For larger pitches the resolution is quickly degrading reaching 80-100 μm at a pitch of 500 μm. The spatial resolution of low-material triple-GEM detectors for the DEUTRON facility at the VEPP-3 storage ring is measured at the extracted beam facility of the VEPP-4M collider. The amount of material in these detectors is reduced by etching the copper of the GEMs electrodes and using a readout structure on a thin kapton foil rather than on a glass fibre plate. The exact amount of material in one DEUTRON detector is measured by studying multiple scattering of 100 MeV electrons in it. The result of these measurements is X/X0 = 2.4×10−3 corresponding to a thickness of the copper layers of the GEM foils of 3 μm. The spatial resolution of one DEUTRON detector is measured with 500 MeV electrons and the measured value is equal to 35 ± 1 μm for orthogonal tracks.

  17. Study of the spatial resolution of low-material GEM tracking detectors

    Science.gov (United States)

    Kudryavtsev, V. N.; Maltsev, T. V.; Shekhtman, L. I.

    2018-02-01

    The spatial resolution of GEM based tracking detectors has been simulated and measured. The simulation includes the GEANT4 based transport of high energy electrons with careful accounting for atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing, including accounting for diffusion, gas amplification fluctuations, the distribution of signals on readout electrodes, electronics noise and a particular algorithm of the final coordinate calculation (center of gravity). The simulation demonstrates that a minimum of the spatial resolution of about 10 μm can be achieved with strip pitches from 250 μm to 300 μm. For larger pitches the resolution is quickly degrading reaching 80-100 μm at a pitch of 500 μm. The spatial resolution of low-material triple-GEM detectors for the DEUTRON facility at the VEPP-3 storage ring is measured at the extracted beam facility of the VEPP-4M collider. The amount of material in these detectors is reduced by etching the copper of the GEMs electrodes and using a readout structure on a thin kapton foil rather than on a glass fibre plate. The exact amount of material in one DEUTRON detector is measured by studying multiple scattering of 100 MeV electrons in it. The result of these measurements is X/X0 = 2.4×10-3 corresponding to a thickness of the copper layers of the GEM foils of 3 μm. The spatial resolution of one DEUTRON detector is measured with 500 MeV electrons and the measured value is equal to 35 ± 1 μm for orthogonal tracks.

  18. Otanps synapse linear relation multiplier circuit

    International Nuclear Information System (INIS)

    Chible, H.

    2008-01-01

    In this paper, a four quadrant VLSI analog multiplier will be proposed, in order to be used in the implementation of the neurons and synapses modules of the artificial neural networks. The main characteristics of this multiplier are the small silicon area and the low power consumption and the high value of the weight input voltage. (author)

  19. On compact multipliers of topological algebras

    International Nuclear Information System (INIS)

    Mohammad, N.

    1994-08-01

    It is shown that if the maximal ideal space Δ(A) of a semisimple commutative complete metrizable locally convex algebra contains no isolated points, then every compact multiplier is trivial. Particularly, compact multipliers on semisimple commutative Frechet algebras whose maximal ideal space has no isolated points are identically zero. (author). 5 refs

  20. Faster and Energy-Efficient Signed Multipliers

    Directory of Open Access Journals (Sweden)

    B. Ramkumar

    2013-01-01

    Full Text Available We demonstrate faster and energy-efficient column compression multiplication with very small area overheads by using a combination of two techniques: partition of the partial products into two parts for independent parallel column compression and acceleration of the final addition using new hybrid adder structures proposed here. Based on the proposed techniques, 8-b, 16-b, 32-b, and 64-b Wallace (W, Dadda (D, and HPM (H reduction tree based Baugh-Wooley multipliers are developed and compared with the regular W, D, H based Baugh-Wooley multipliers. The performances of the proposed multipliers are analyzed by evaluating the delay, area, and power, with 65 nm process technologies on interconnect and layout using industry standard design and layout tools. The result analysis shows that the 64-bit proposed multipliers are as much as 29%, 27%, and 21% faster than the regular W, D, H based Baugh-Wooley multipliers, respectively, with a maximum of only 2.4% power overhead. Also, the power-delay products (energy consumption of the proposed 16-b, 32-b, and 64-b multipliers are significantly lower than those of the regular Baugh-Wooley multiplier. Applicability of the proposed techniques to the Booth-Encoded multipliers is also discussed.

  1. Temperature Insensitive Current-Mode Four Quadrant Multiplier Using Single CFCTA

    Directory of Open Access Journals (Sweden)

    Tuntrakool Sunti

    2017-01-01

    Full Text Available A four quadrant multiplier of two current input signals using active building block, namely current follower cascaded transconductance amplifier (CFCTA is presented in this paper. The proposed multiplier consists of only single CFCTA without the use of any passive element. The presented circuit has low impedance at current input node and high impedance at current output node which is convenient for cascading in current mode circuit without the need of current buffer circuits. The output current can multiply two input currents with temperature insensitivity. Moreover, the magnitude of output current can be controlled electronically via DC bias current. With only single active building block, the presented multiplier is suitable for integrated circuit implementation for analog signal processing. Simulation results from a PSpice program are presented in order to demonstrate the multiplier proposed here.

  2. Multiply-negatively charged aluminium clusters and fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Noelle

    2008-07-15

    Multiply negatively charged aluminium clusters and fullerenes were generated in a Penning trap using the 'electron-bath' technique. Aluminium monoanions were generated using a laser vaporisation source. After this, two-, three- and four-times negatively charged aluminium clusters were generated for the first time. This research marks the first observation of tetra-anionic metal clusters in the gas phase. Additionally, doubly-negatively charged fullerenes were generated. The smallest fullerene dianion observed contained 70 atoms. (orig.)

  3. Analysis of Mechanical Properties for GEM Foil

    CERN Document Server

    Chin, Yuk Ming

    2016-01-01

    In view of new assembly technique of the GEM detector; in which three foils stack is stretched to get the uniform gaps among the foils. We studied the mechanical properties of the foil material. We conditioned the samples in different environments to make them extra dry and wet. As holes are the major source of the charge amplification their deformation can effect the detector performance. Therefore in our studies we also studied at which level of the stress the holes deformation is seen. These tensile and holes deformation studies can help to optimize the stress during detector assembly.

  4. Analysis of activation yields by INC/GEM

    International Nuclear Information System (INIS)

    Furihata, Shiori; Nakashima, Hiroshi

    2001-01-01

    Excitation functions of the nuclides produced from the reaction on nitrogen and oxygen target irradiated by nucleons are analyzed using INC/GEM. It is shown that INC/GEM reproduces most of the cross sections within a factor of two to three. (author)

  5. Extending the ISC-GEM Global Earthquake Instrumental Catalogue

    Science.gov (United States)

    Di Giacomo, Domenico; Engdhal, Bob; Storchak, Dmitry; Villaseñor, Antonio; Harris, James

    2015-04-01

    After a 27-month project funded by the GEM Foundation (www.globalquakemodel.org), in January 2013 we released the ISC-GEM Global Instrumental Earthquake Catalogue (1900 2009) (www.isc.ac.uk/iscgem/index.php) as a special product to use for seismic hazard studies. The new catalogue was necessary as improved seismic hazard studies necessitate that earthquake catalogues are homogeneous (to the largest extent possible) over time in their fundamental parameters, such as location and magnitude. Due to time and resource limitation, the ISC-GEM catalogue (1900-2009) included earthquakes selected according to the following time-variable cut-off magnitudes: Ms=7.5 for earthquakes occurring before 1918; Ms=6.25 between 1918 and 1963; and Ms=5.5 from 1964 onwards. Because of the importance of having a reliable seismic input for seismic hazard studies, funding from GEM and two commercial companies in the US and UK allowed us to start working on the extension of the ISC-GEM catalogue both for earthquakes that occurred beyond 2009 and for earthquakes listed in the International Seismological Summary (ISS) which fell below the cut-off magnitude of 6.25. This extension is part of a four-year program that aims at including in the ISC-GEM catalogue large global earthquakes that occurred before the beginning of the ISC Bulletin in 1964. In this contribution we present the updated ISC GEM catalogue, which will include over 1000 more earthquakes that occurred in 2010 2011 and several hundreds more between 1950 and 1959. The catalogue extension between 1935 and 1949 is currently underway. The extension of the ISC-GEM catalogue will also be helpful for regional cross border seismic hazard studies as the ISC-GEM catalogue should be used as basis for cross-checking the consistency in location and magnitude of those earthquakes listed both in the ISC GEM global catalogue and regional catalogues.

  6. Keynesian multiplier versus velocity of money

    Science.gov (United States)

    Wang, Yougui; Xu, Yan; Liu, Li

    2010-08-01

    In this paper we present the relation between Keynesian multiplier and the velocity of money circulation in a money exchange model. For this purpose we modify the original exchange model by constructing the interrelation between income and expenditure. The random exchange yields an agent's income, which along with the amount of money he processed determines his expenditure. In this interactive process, both the circulation of money and Keynesian multiplier effect can be formulated. The equilibrium values of Keynesian multiplier are demonstrated to be closely related to the velocity of money. Thus the impacts of macroeconomic policies on aggregate income can be understood by concentrating solely on the variations of money circulation.

  7. R\\&D results on a CsI-coated triple thick GEM-based photodetector

    CERN Document Server

    Martinengo, P; Paic, G; Paras, D M; Di Mauro, A; van Hoorne, J; Molnar, L; Peskov, V; Breskin, A

    2011-01-01

    The very high momentum particle identification detector proposed for the ALICE upgrade is a focusing RICH using a C(4)F(10) gaseous radiator. For the detection of Cherenkov photons, one of the options currently under investigation is to use a CsI-coated triple thick GEM with metallic or resistive electrodes. We will present results from the laboratory studies as well as preliminary results of beam tests of a RICH detector prototype consisting of a CaF(2) radiator coupled to a 10 x 10 cm(2) CsI-coated triple thick GEM equipped with a pad readout and GASSIPLEX-based front-end electronics. With such a prototype the detection of Cherenkov photons simultaneously with minimum ionizing particles has been achieved for the first time in a stable operation mode. (C) 2010 Elsevier B.V. All rights reserved.

  8. Multipliers for continuous frames in Hilbert spaces

    International Nuclear Information System (INIS)

    Balazs, P; Bayer, D; Rahimi, A

    2012-01-01

    In this paper, we examine the general theory of continuous frame multipliers in Hilbert space. These operators are a generalization of the widely used notion of (discrete) frame multipliers. Well-known examples include anti-Wick operators, STFT multipliers or Calderón–Toeplitz operators. Due to the possible peculiarities of the underlying measure spaces, continuous frames do not behave quite as their discrete counterparts. Nonetheless, many results similar to the discrete case are proven for continuous frame multipliers as well, for instance compactness and Schatten-class properties. Furthermore, the concepts of controlled and weighted frames are transferred to the continuous setting. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Coherent states: mathematical and physical aspects’. (paper)

  9. Economic Multipliers and Mega-Event Analysis

    OpenAIRE

    Victor Matheson

    2004-01-01

    Critics of economic impact studies that purport to show that mega-events such as the Olympics bring large benefits to the communities “lucky” enough to host them frequently cite the use of inappropriate multipliers as a primary reason why these impact studies overstate the true economic gains to the hosts of these events. This brief paper shows in a numerical example how mega-events may lead to inflated multipliers and exaggerated claims of economic benefits.

  10. Charge-exchange collisions of multiply charged ions with atoms

    International Nuclear Information System (INIS)

    Grozdanov, T.P.; Janev, R.K.

    1978-01-01

    The problem of electron transfer between neutral atoms and multiply charged ions is considered at low and medium energies. It is assumed that a large number of final states are available for the electron transition so that the electron-capture process is treated as a tunnel effect caused by the strong attractive Coulomb field of the multicharged ions. The electron transition probability is obtained in a closed form using the modified-comparison-equation method to solve the Schroedinger equation. An approximately linear dependence of the one-electron transfer cross section on the charge of multicharged ion is found. Cross-section calculations of a number of charge-exchange reactions are performed

  11. Gems of combinatorial optimization and graph algorithms

    CERN Document Server

    Skutella, Martin; Stiller, Sebastian; Wagner, Dorothea

    2015-01-01

    Are you looking for new lectures for your course on algorithms, combinatorial optimization, or algorithmic game theory?  Maybe you need a convenient source of relevant, current topics for a graduate student or advanced undergraduate student seminar?  Or perhaps you just want an enjoyable look at some beautiful mathematical and algorithmic results, ideas, proofs, concepts, and techniques in discrete mathematics and theoretical computer science?   Gems of Combinatorial Optimization and Graph Algorithms is a handpicked collection of up-to-date articles, carefully prepared by a select group of international experts, who have contributed some of their most mathematically or algorithmically elegant ideas.  Topics include longest tours and Steiner trees in geometric spaces, cartograms, resource buying games, congestion games, selfish routing, revenue equivalence and shortest paths, scheduling, linear structures in graphs, contraction hierarchies, budgeted matching problems, and motifs in networks.   This ...

  12. Performance of GEM detectors in high intensity particle beams

    CERN Document Server

    Bachmann, S; Ketzer, B; Deutel, M; Ropelewski, Leszek; Sauli, Fabio; Bondar, A E; Buzulutskov, A F; Shekhtman, L I; Sokolov, A; Tatarinov, A A; Vasilev, A; Kappler, S; Schulte, E C

    2001-01-01

    We describe extensive tests of Double GEM and Triple GEM detectors, including full size prototypes for the COMPASS experiment, exposed to high intensity muon, proton and pion beams at the Paul~Scherrer Institute and at CERN. The measurements aim at detecting problems possible under these operation conditions, the main concern being the occurrence of discharges induced by beam particles. Results on the dependence of the probability for induced discharges on the experimental environment are presented and discussed. Implications for the application of GEM~detectors in experiments at high luminosity colliders are illustrated.

  13. Portable XRF: A Tool for the Study of Corundum Gems

    Directory of Open Access Journals (Sweden)

    Barone Germana

    2017-09-01

    Full Text Available Origin of gemstones is a key aspect not only in gemological field but also in Cultural Heritage studies, for the correct evaluation of precious artifacts. The studies on gems require the application of non-invasive and non-destructive methods; among them, portable spectroscopic techniques has been demonstrated as powerful tools, providing a fingerprint of gems for origin and provenance determination. In this study, portable XRF spectroscopy has been applied to test the potential of the technique for the origin determination of corundum gems. The obtained results allowed distinguishing natural and synthetic rubies and sapphires.

  14. Monolithic front-end ICs for interpolating cathode pad and strip detectors for GEM

    International Nuclear Information System (INIS)

    O'Connor, P.

    1993-05-01

    We are developing CMOS circuits for readout of interpolating cathode strip and pad chambers for the GEM experiment at the SSC. Because these detectors require position resolution of about 1% of the strip pitch, the electronic noise level must be less than 2000 electrons. Several test chips have been fabricated to demonstrate the feasibility of achieving the combination of low noise, speed, and wide dynamic range in CMOS. Results to date show satisfactory noise and linearity performance. Future development will concentrate on radiation-hardening the central tracker ASIC design, optimizing the shaper peaking time and noise contribution, providing more user-configurable output options, and packaging and test issues

  15. A GEM readout with radial zigzag strips and linear charge-sharing response

    Science.gov (United States)

    Zhang, Aiwu; Hohlmann, Marcus; Azmoun, Babak; Purschke, Martin L.; Woody, Craig

    2018-04-01

    We study the position sensitivity of radial zigzag strips intended to read out large GEM detectors for tracking at future experiments. Zigzag strips can cover a readout area with fewer strips than regular straight strips while maintaining good spatial resolution. Consequently, they can reduce the number of required electronic channels and related cost for large-area GEM detector systems. A non-linear relation between incident particle position and hit position measured from charge sharing among zigzag strips was observed in a previous study. We significantly reduce this non-linearity by improving the interleaving of adjacent physical zigzag strips. Zigzag readout structures are implemented on PCBs and on a flexible foil and are tested using a 10 cm × 10 cm triple-GEM detector scanned with a strongly collimated X-ray gun on a 2D motorized stage. Angular resolutions of 60-84 μrad are achieved with a 1.37 mrad angular strip pitch at a radius of 784 mm. On a linear scale this corresponds to resolutions below 100 μm.

  16. A Cylindrical GEM Detector with Analog Readout for the BESIII Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Cibinetto, G. [BESIII CGEM group, INFN Ferrara (Italy)

    2015-07-01

    Inner Trackers (IT) are key detectors in Particle Physics experiments; excellent spatial resolution, radiation transparency and hardness, and operability under high occupancies are main requirements. We aim to design, build and commission by 2017 a Cylindrical GEM (CGEM) detector candidate to be the new IT of the BESIII spectrometer, hosted on BEPC2 in IHEP, Beijing; BESIII data taking will last until at least 2020. The IT itself will represent an evolution w.r.t. the state of the art of GEM detectors, since the use of new kind of mechanical supports for the GEM foils will reduce the total radiation length of the detector and improve its tracking performance; an innovative design of the CGEM anode will allow for smaller capacitance and hence for bigger signals. The relatively strong BESIII magnetic field requires a new analogue readout; full custom front-end electronics, including a dedicated ASIC, will be designed and produced for optimal data collection. Prototype Beam Test results showing the measurement of the spatial resolution in a 1 Tesla magnetic field will be presented among with the mechanical design and simulations. (authors)

  17. Limits of a spatial resolution of the cascaded GEM based detectors

    International Nuclear Information System (INIS)

    Kudryavtsev, V.N.; Maltsev, T.V.; Shekhtman, L.I.

    2017-01-01

    Spatial resolution of tracking detectors based on GEM cascades is determined in the simulation and measured. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting for atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing taking into account diffusion, gas amplification fluctuations, the distribution of signals over readout electrodes, electronics noise and particular algorithm of final coordinate calculation (centre-of-gravity algorithm). The simulation demonstrates that the minimum of the spatial resolution of about 10–20 μm can be achieved with a gas mixture of Ar-CO 2 (75%–25%) at a strip pitch in the range from 250 μm to 300 μm. At a larger pitch the resolution quickly degrades reaching 70–100 μm at a pitch of 450–500 μm. The reasons of such behavior are discussed and corresponding hypothesis is tested. Particularly, the effect of electron cloud modification due to a GEM operation is considered using the ANSYS and Garfield++ simulation programs. The detection efficiency and spatial resolution of low-material triple-GEM detectors for the DEUTERON facility at BINP are measured at the extracted beam facility of the VEPP-4M collider. One-coordinate resolution of two detectors for the DEUTERON facility is measured with a 2 GeV electron beam. The determined values of the detectors' spatial resolution is equal to 46.6 ± 0.1 μm and 38.5 ± 0.2 μm for orthogonal tracks in two detectors, respectively.

  18. Limits of a spatial resolution of the cascaded GEM based detectors

    Science.gov (United States)

    Kudryavtsev, V. N.; Maltsev, T. V.; Shekhtman, L. I.

    2017-06-01

    Spatial resolution of tracking detectors based on GEM cascades is determined in the simulation and measured. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting for atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing taking into account diffusion, gas amplification fluctuations, the distribution of signals over readout electrodes, electronics noise and particular algorithm of final coordinate calculation (centre-of-gravity algorithm). The simulation demonstrates that the minimum of the spatial resolution of about 10-20 μm can be achieved with a gas mixture of Ar-CO2 (75%-25%) at a strip pitch in the range from 250 μm to 300 μm. At a larger pitch the resolution quickly degrades reaching 70-100 μm at a pitch of 450-500 μm. The reasons of such behavior are discussed and corresponding hypothesis is tested. Particularly, the effect of electron cloud modification due to a GEM operation is considered using the ANSYS and Garfield++ simulation programs. The detection efficiency and spatial resolution of low-material triple-GEM detectors for the DEUTERON facility at BINP are measured at the extracted beam facility of the VEPP-4M collider. One-coordinate resolution of two detectors for the DEUTERON facility is measured with a 2 GeV electron beam. The determined values of the detectors' spatial resolution is equal to 46.6 ± 0.1 μm and 38.5 ± 0.2 μm for orthogonal tracks in two detectors, respectively.

  19. Control and supervision of a time projection chamber with GEM readout; Steuerung und Ueberwachung einer Zeitprojektionskammer mit GEM-Auslese

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, David

    2014-02-03

    To get a deeper understanding of the structure of nucleons and the strong interaction binding the constituents inside, the CBELSA/TAPS experiment investigates the resonance spectrum of baryons by meson photoproduction within the scope of the SFB/TRR 16 ''Subnuclear Structure of Matter''. In order to support and expand the physical program, the existing Inner Detector will be replaced by a Time Projection Chamber (TPC) within the next few years. This allows for the detection of charged reaction channels, which can't be measured with the CBELSA/TAPS experiment up to now, as well as for particle identification from the specific energy loss. A First prototype with GEM foils for charge amplification in front of the readout plane and suitable size for the CBELSA/TAPS experiment was built in collaboration with the TU Munich, the detector laboratory of the GSI in Darmstadt and the Stefan-Meyer-Institute of the University Vienna. The TPC has been commissioned successfully within the FOPI experiment at the GSI during several test beam campaigns. Additionally, systematic studies have been carried out with a smaller Test-TPC using a TestBench providing an accurate external track definition. As the electron drift velocity in the TPC volume is a crucial parameter for the exact track reconstruction, detailed simulations of the drift velocity and its dependency on external parameters, such as drift voltage, pressure, gas flow or temperature, have been carried out. The results of these simulations recommend a constant monitoring of all examined parameters to allow a reasonable use of the simulated drift velocities. For this purpose, and to ensure a safe and stable operation of the TPCs and the other detectors on the TestBench, the required hardware, the control software based on a data base and a graphical user interface were designed and constructed as the main part of this work. With this so-called SlowControl, it was possible to measure, control and

  20. Bio/Nano Electronic Devices and Sensors

    National Research Council Canada - National Science Library

    Jones, W. K

    2008-01-01

    ...) Cold cathode microwave generator and ceramic electron multiplier-ceramic multiplier using a novel secondary electron yield materials of MgO and CNT was demonstrated as well as cooling structures...

  1. SYNTHESIS AND POLYMERIZATION OF GEM-METHYL(VINYLBENZYL)TETRACHLOROCYCLOTRIPHOSPHAZENE

    NARCIS (Netherlands)

    BOSSCHER, G; VANDEGRAMPEL, JC

    A new styrene-substituted chlorocyclotriphosphazene, gem-methyl(vinylbenzyl) tetrachlorocyclotriphosphazene, has been prepared from vinylbenzylmagnesium chloride and hexachlorocyclotriphosphazene. The organosubstituted chlorocyclotriphosphazene has been used in radical homo- and copolymerization

  2. A gravity model for crustal dynamics (GEM-L2)

    Science.gov (United States)

    Lerch, F. J.; Klosko, S. M.; Patel, G. B.; Wagner, C. A.

    1985-01-01

    The Laser Geodynamics Satellite (Lageos) was the first NASA satellite which was placed into orbit exclusively for laser ranging applications. Lageos was designed to permit extremely accurate measurements of the earth's rotation and the movement of the tectonic plates. The Goddard earth model, GEM-L2, was derived mainly on the basis of the precise laser ranging data taken on many satellites. Douglas et al. (1984) have demonstrated the utility of GEM-L2 in detecting the broadest ocean circulations. As Lageos data constitute the most extensive set of satellite laser observations ever collected, the incorporation of 2-1/2 years of these data into the Goddard earth models (GEM) has substantially advanced the geodynamical objectives. The present paper discusses the products of the GEM-L2 solution.

  3. Wits Post Graduate Symposium Poster - iGEM

    CSIR Research Space (South Africa)

    Millroy, L

    2010-08-01

    Full Text Available This document is a poster providing details of the 2010 International Genetically Engineered Machines (iGEM) competition. The origins of the competition, as well as criteria, judging, sponsors, topic and team, are briefly described....

  4. Toward improved guideline quality: using the COGS statement with GEM.

    Science.gov (United States)

    Shiffman, Richard N; Michel, Georges

    2004-01-01

    The Conference on Guideline Standardization (COGS) was convened to create a standardized documentation checklist for clinical practice guidelines in an effort to promote guideline quality and facilitate implementation. The statement was created by a multidisciplinary panel using a rigorous consensus development methodology. The Guideline Elements Model (GEM) provides a standardized approach to representing guideline documents using XML. In this work, we demonstrate the sufficiency of GEM for describing COGS components. Using the mapping between COGS and GEM elements we built an XSLT application to examine a guideline's adherence (or non-adherence) to the COGS checklist. Once a guideline has been marked up according to the GEM hierarchy, its knowledge content can be reused in multiple ways.

  5. Performance of an optical readout GEM-based TPC

    International Nuclear Information System (INIS)

    Margato, L.M.S.; Fraga, F.A.F.; Fetal, S.T.G.; Fraga, M.M.F.R.; Balau, E.F.S.; Blanco, A.; Marques, R. Ferreira; Policarpo, A.J.P.L

    2004-01-01

    We report on the operation of a GEM-based small TPC using an optical readout. The detector was operated with a mixture of Ar+CF 4 using 5.48 MeV alpha particles obtained from a 241 Am source and the GEM scintillation was concurrently read by a CCD camera and a photomultiplier. Precision collimators were used to define the track orientation. Qualitative results on the accuracy of the track angle, length and charge deposition measurements are presented

  6. GEMS Revealed: Spectrum Imaging of Aggregate Grains in Interplanetary Dust

    Science.gov (United States)

    Keller, L. P.; Messenger, S.; Christoffersen, R.

    2005-01-01

    Anhydrous interplanetary dust particles (IDPs) of cometary origin contain abundant materials that formed in the early solar nebula. These materials were transported outward and subsequently mixed with molecular cloud materials and presolar grains in the region where comets accreted [1]. GEMS (glass with embedded metal and sulfides) grains are a major component of these primitive anhydrous IDPs, along with crystalline Mg-rich silicates, Fe-Ni sulfides, carbonaceous material, and other trace phases. Some GEMS grains (5%) are demonstrably presolar based on their oxygen isotopic compositions [2]. However, most GEMS grains are isotopically solar and have bulk chemical compositions that are incompatible with inferred compositions of interstellar dust, suggesting a solar system origin [3]. An alternative hypothesis is that GEMS grains represent highly irradiated interstellar grains whose oxygen isotopic compositions were homogenized through processing in the interstellar medium (ISM) [4]. We have obtained the first quantitative X-ray maps (spectrum images) showing the distribution of major and minor elements in individual GEMS grains. Nanometer-scale chemical maps provide critical data required to evaluate the differing models regarding the origin of GEMS grains.

  7. Measurement of Z boson production in association with jets at the LHC and study of a DAQ system for the Triple-GEM detector in view of the CMS upgrade

    CERN Document Server

    Léonard, Alexandre

    This PhD thesis presents the measurement of the differential cross section for the production of a Z boson in association with jets in proton-proton collisions taking place at the Large Hadron Collider (LHC) at CERN, at a centre-of-mass energy of 8 TeV. A development of a data acquisition (DAQ) system for the Triple-Gas Electron Multiplier (GEM) detector in view of the Compact Muon Solenoid (CMS) detector upgrade is also presented. The events used for the data analysis were collected by the CMS detector during the year 2012 and constitute a sample of 19.6/fb of integrated luminosity. The cross section measurements are performed as a function of the jet multiplicity, the jet transverse momentum and pseudorapidity, and the scalar sum of the jet transverse momenta. The results were obtained by correcting the observed distributions for detector effects. The measured differential cross sections are compared to some state of the art Monte Carlo predictions MadGraph 5, Sherpa 2 and MadGraph5_aMC@NLO. These measureme...

  8. PREFACE: Science's gem: diamond science 2009 Science's gem: diamond science 2009

    Science.gov (United States)

    Mainwood, Alison; Newton, Mark E.; Stoneham, Marshall

    2009-09-01

    diamond's exceptional properties for quantum information processing [2], a topic on which there have been many recent papers, and where a diamond colour centre single photon source is already commercially available. Biomedical applications of diamond are recognised, partly tribological and partly electrochemical, but lie outside the present group of papers. Processing and controlling diamond surfaces and interfaces with other materials in their environment are critical steps en route to exploitation. Boron-doped diamond has already found application in electro-analysis and in the bulk oxidation of dissolved species in solution [3]. Energy-related applications—ranging from high-power electronics [3] to a potential first wall of fusion reactors [4]—are further exciting potential applications. Even small and ugly diamonds have value. Their mechanical properties [5] dominate, with significant niche applications such as thermal sinks. The major applications for diamond to date exploit only a fraction of diamond's special properties: visual for status diamonds, and mechanical for working diamonds. Diamond physics reaches well beyond the usual laboratory, to the geological diamond formation processes in the Earth's mantle. Characterization of natural gem diamonds [6, 7] is one part of the detective story that allows us to understand the conditions under which they formed. It was only half a century ago that the scientific and technological challenges of diamond synthesis were met systematically. Today, most of the recent research on diamond has concentrated on synthetics, whether created using high pressure, high temperature (HPHT) techniques or chemical vapour deposition (CVD). The HPHT synthesis of diamond has advanced dramatically [8, 9] to the extent that dislocation birefringence [10] can be largely eliminated. In silicon technology, the elimination of dislocations was a major step in microelectronics. Now, even diamond can be synthesised containing virtually no

  9. Precision meson spectroscopy. Diffractive production at COMPASS and development of a GEM-based TPC for PANDA

    International Nuclear Information System (INIS)

    Weitzel, Quirin

    2008-01-01

    ) has been proposed for the central tracker of PANDA. A continuous operation without ion gate is foreseen, which constitutes a novel development in high-rate particle physics experiments. Gas Electron Multiplier (GEM) foils offer an intrinsic ion back-flow suppression combined with high gains, and will therefore be used for gas amplification. A small-size GEM-TPC test chamber has been constructed during this thesis and commissioned using both X-rays and muons from cosmic-ray air-showers. From the latter data, a spatial resolution down to 140 μm has been achieved. The detector has been operated stably for many months with Ar/CO 2 (70/30) and at typical gas amplification factors of (5-10).10 3 . (orig.)

  10. Precision meson spectroscopy. Diffractive production at COMPASS and development of a GEM-based TPC for PANDA

    Energy Technology Data Exchange (ETDEWEB)

    Weitzel, Quirin

    2008-09-24

    . Due to its excellent tracking capabilities for charged particles, a time projection chamber (TPC) has been proposed for the central tracker of PANDA. A continuous operation without ion gate is foreseen, which constitutes a novel development in high-rate particle physics experiments. Gas Electron Multiplier (GEM) foils offer an intrinsic ion back-flow suppression combined with high gains, and will therefore be used for gas amplification. A small-size GEM-TPC test chamber has been constructed during this thesis and commissioned using both X-rays and muons from cosmic-ray air-showers. From the latter data, a spatial resolution down to 140 {mu}m has been achieved. The detector has been operated stably for many months with Ar/CO{sub 2} (70/30) and at typical gas amplification factors of (5-10).10{sup 3}. (orig.)

  11. The GEM Theory of the Unification of Gravitation and Electro-Magnetism

    Science.gov (United States)

    Brandenburg, J. E.

    2012-01-01

    The GEM (Gravity Electro-Magnetism), theory is presented as an alloy of Sakharov and Kaluza-Klein approaches to field unification. GEM uses the concept of gravity fields as Poynting fields to postulate that the non-metric portion of the EM stress tensor becomes the metric tensor in strong fields leading to "self-censorship". Covariant formulation of the GEM theory is accomplished through definition of the spacetime metric tensor as a portion of the EM stress tensor normalized by its own trace: gab = 4(FcaFcb )/(FabFab), it is found that this results in a massless ground state vacuum and a Newtonian gravitation potential f=1/2 E2/B2 =GM/r , where E, B and F are part of the vacuum Zero Point Fluctuation (ZPF) and M and r are the mass and distance from the center of a gravitating body and G is the Newton gravitation constant. It is found that a Lorentz flat-space metric is recovered in the limit of a vacuum full spectrum ZPF. The vacuum ZPF energy and vacuum quantities G, h, c, gives birth to particles quantities mp, me, e,-e in a process triggered by the appearance of the Kaluza-Klein fifth dimension, where also the EM and gravity forces split from each other in a process correlated to the splitting apart of protons and electrons. The separate appearance of the proton and electron occurs as the splitting of a light-like spacetime interval of zero-length into a finite space-like portion containing three subdimensions identified with the quarks and a time-like portion identified with the electron. The separation of mass with charge for the electron and proton pair comes about from a U(1) symmetry with a rotation in imaginary angle. A logarithmic variation of charge with mass for the proton-electron pair results and leads to the formula ln(ro/rp) = s, where s = (mp/me)1/2 , where mp and me are the electron and proton masses respectively and where ro =e2/moc2 , and where mo = (mpme)1/2 and where rp is the Planck length . This leads to the formula G=e2/mo2aexp(-2s)=6

  12. Semigroups of Herz-Schur multipliers

    DEFF Research Database (Denmark)

    Knudby, Søren

    2014-01-01

    function (see Theorem 1.2). It is then shown that a (not necessarily proper) generator of a semigroup of Herz–Schur multipliers splits into a positive definite kernel and a conditionally negative definite kernel. We also show that the generator has a particularly pleasant form if and only if the group...

  13. A quantum architecture for multiplying signed integers

    International Nuclear Information System (INIS)

    Alvarez-Sanchez, J J; Alvarez-Bravo, J V; Nieto, L M

    2008-01-01

    A new quantum architecture for multiplying signed integers is presented based on Booth's algorithm, which is well known in classical computation. It is shown how a quantum binary chain might be encoded by its flank changes, giving the final product in 2's-complement representation.

  14. A 40 GByte/s read-out system for GEM

    International Nuclear Information System (INIS)

    Bowden, M.; Carrel, J.; Dorenbosch, J.; Kapoor, V.

    1994-04-01

    The preliminary design of the read-out system for the GEM (Gammas, Electrons, Muons) detector at the Superconducting Super Collider is presented. The system reads all digitized data from the detector data sources at a Level 1 trigger rate of up to 100 kHz. A total read-out bandwidth of 40 GBytes/s is available. Data are stored in buffers that are accessible for further event filtering by an on-line, processor farm. Data are transported to the farm only as they are needed by the higher-level trigger algorithms, leading to a reduced bandwidth requirement in the Data Acquisition System

  15. Auger transitions in singly and multiply ionized atoms

    International Nuclear Information System (INIS)

    Mehlhorn, W.

    1978-01-01

    Some recent progress in Auger and autoionizing electron spectrometry of free metal atoms and of multiply ionized atoms is reviewed. The differences which arise between the spectra of atoms in the gaseous and the solid state are due to solid state effects. This will be shown for Cd as an example. The super Coster-Kronig transitions 3p-3d 2 (hole notation) and Coster-Kronig transitions 3p-3d 4s have been measured and compared with free-atom calculations for free Zn atoms. The experimental width GAMMA(3p)=(2.1+-0.2)eV found for the free atom agrees with the value obtained for solid Zn but is considerably smaller than the theoretical value for the free atom. Autoionizing spectra of Na following an L-shell excitation or ionization by different particles are compared and discussed. The nonisotropic angular distribution of electrons from the transition 2p 5 3s 2 2 Psub(3/2)→2p 6 +e - is compared with theoretical calculations. Two examples for Auger spectrometry of multiply ionized atoms are given: (1) excitation of neon target atoms by light and heavy ions, and (2) excitation of projectile ions Be + and B + in single gas collisions with CH 4 . A strong alignment of the excited atoms has also been found here

  16. nGEM fast neutron detectors for beam diagnostics

    International Nuclear Information System (INIS)

    Croci, G.; Claps, G.; Cavenago, M.; Dalla Palma, M.; Grosso, G.; Murtas, F.; Pasqualotto, R.; Perelli Cippo, E.; Pietropaolo, A.; Rebai, M.; Tardocchi, M.; Tollin, M.; Gorini, G.

    2013-01-01

    Fast neutron detectors with a sub-millimetric space resolution are required in order to qualify neutron beams in applications related to magnetically-controlled nuclear fusion plasmas and to spallation sources. A nGEM detector has been developed for the CNESM diagnostic system of the SPIDER NBI prototype for ITER and as beam monitor for fast neutrons lines at spallation sources. The nGEM is a triple GEM gaseous detector equipped with polypropylene and polyethylene layers used to convert fast neutrons into recoil protons through the elastic scattering process. This paper describes the results obtained by testing a nGEM detector at the ISIS spallation source on the VESUVIO beam line. Beam profiles (σ x =14.35 mm, σ y =15.75 mm), nGEM counting efficiency (around 10 -4 for 3 MeV n <15 MeV), detector stability (≈4.5%) and the effect of filtering the beam with different type of materials were successfully measured. The x beam profile was compared to the one measured by a single crystal diamond detector. Finally, the efficiency of the detector was simulated exploiting the GEANT4 tool

  17. Hydrogen retention behavior of beryllides as advanced neutron multipliers

    Directory of Open Access Journals (Sweden)

    Y. Fujii

    2016-12-01

    Full Text Available Beryllium intermetallic compounds (beryllides are the most promising candidate materials for use as advanced neutron multipliers in future fusion reactors because of their low swelling and high stability at high temperatures. Recently, beryllium–titanium beryllide pebbles such as Be12Ti have been successfully fabricated using a novel granulation process. In this study, the fundamental aspects of the behavior of hydrogen isotopes in Be12Ti pebbles were investigated via thermal desorption spectroscopy and transmission electron microscopy. In addition, atomistic calculations using first principles electronic-structure methods were applied to determine the solution energy of hydrogen in Be12Ti. The results showed simpler and weaker hydrogen-trapping efficiency for Be12Ti than for pure Be.

  18. Outer-shell transitions in collisions between multiply charged ions and atoms

    International Nuclear Information System (INIS)

    Bloemen, E.W.P.

    1980-01-01

    The study of collisions between multiply charged ions and atoms (molecules) is of importance in different areas of research. Usually, the most important process is capture of an electron from the target atom into the projectile ion. In most cases the electron goes to an excited state of the projectile ion. These electron capture processes are studied. The author also studied direct excitation of the target atom and of the projectile ion. (Auth.)

  19. GEMs with Double Layred Micropattern Electrodes and their Applications

    CERN Document Server

    Di Mauro, A.; Nappi, E.; Oliveira, R.; Peskov, V.; Pietropaolo, F.; Picchi, P.

    We have developed and tested several new designs of GEM detectors with micropattern electrodes manufactured by microelectronic technology. In one design, the inner layer of the detector electrode consists of thin metallic strips and the outer layer is made of a resistive grid manufactured by a screen printing technology. In other designs, the electrodes were made of metallic strips fed by HV via micro-resistors manufactured by a screen printing technology. Due to these features, the new detectors have several important advantages over conventional GEMs or ordinary thick GEMs. For example, the resistive grid (in the first design) and the screen printed resistors (in other designs) limited the current in case of discharges, making these detectors intrinsically spark-protected. We will here describe our tests with the photosensitive versions of these detectors (coated with CsI layers) and the efforts of implementing them in several applications. In particular, we will focus on our activity towards the ALICE RICH...

  20. Experimental and Theoretical Progress on the GEM Theory

    Science.gov (United States)

    Brandenburg, J. E.

    This paper reports experimental and theoretical progress on the GEM unification theory. In theoretical progress, the derivation of the GEM theory using it in a fully covariant form is achieved based on the principle of self-cancellation of the ZPF EM stress-momentum tensor. This derivation reveals that the final Gravity-EM system obeys a Helmholtz-like equation resembling that governing sound propagation. Finally an improved derivation of the formula for the Newton Gravitation constant is shown, qresulting in the formula G = e2/(4πɛ0 me mp) α exp (-2 (α-.86/σ2…) = 6.673443 x10-11 N-m2 kg-2 that agrees with experimental values to 3 parts per 100,000. Experiments have found parity violating weight reductions in gyroscopes driven by rotating EM fields. These experiments appear to confirm gravity modification using electromagnetism predicted by the GEM theory through the Vacuum Bernoulli Equation.

  1. Equations for the stochastic cumulative multiplying chain

    Energy Technology Data Exchange (ETDEWEB)

    Lewins, J D [Cambridge Univ. (UK). Dept. of Engineering

    1980-01-01

    The forward and backward equations for the conditional probability of the neutron multiplying chain are derived in a new generalization accounting for the chain length and admitting time dependent properties. These Kolmogorov equations form the basis of a variational and hence complete description of the 'lumped' multiplying system. The equations reduce to the marginal distribution, summed over all chain lengths, and to the simpler equations previously derived for that problem. The method of derivation, direct and in the probability space with the minimum of mathematical manipulations, is perhaps the chief attraction: the equations are also displayed in conventional generating function form. As such, they appear to apply to number of problems in areas of social anthropology, polymer chemistry, genetics and cell biology as well as neutron reactor theory and radiation damage.

  2. Equations for the stochastic cumulative multiplying chain

    International Nuclear Information System (INIS)

    Lewins, J.D.

    1980-01-01

    The forward and backward equations for the conditional probability of the neutron multiplying chain are derived in a new generalization accounting for the chain length and admitting time dependent properties. These Kolmogorov equations form the basis of a variational and hence complete description of the 'lumped' multiplying system. The equations reduce to the marginal distribution, summed over all chain lengths, and to the simpler equations previously derived for that problem. The method of derivation, direct and in the probability space with the minimum of mathematical manipulations, is perhaps the chief attraction: the equations are also displayed in conventional generating function form. As such, they appear to apply to number of problems in areas of social anthropology, polymer chemistry, genetics and cell biology as well as neutron reactor theory and radiation damage. (author)

  3. Tourism multipliers in the Mexican economy

    Directory of Open Access Journals (Sweden)

    Antonio Kido-Cruz

    2016-12-01

    Full Text Available This paper presents an analysis of the multiplier impact generated by the tourism sector in Mexico in the year 2013. The importance of studying this sector, in particular, lies in its contribution to the National GDP of over 8% and in its promising development based on services’ quality and the preferred destination of the developed countries. In addition, it is proposed to simulate the multiplier impact that will generate two current events, as they are, the construction of the new International Airport of Mexico and the increase of the investment in Fibers. The results were very punctual, a better distribution of the investment is generated, it is invested in the tourism sector, mainly in variables such as value added and remuneration.

  4. Integrated optic vector-matrix multiplier

    Science.gov (United States)

    Watts, Michael R [Albuquerque, NM

    2011-09-27

    A vector-matrix multiplier is disclosed which uses N different wavelengths of light that are modulated with amplitudes representing elements of an N.times.1 vector and combined to form an input wavelength-division multiplexed (WDM) light stream. The input WDM light stream is split into N streamlets from which each wavelength of the light is individually coupled out and modulated for a second time using an input signal representing elements of an M.times.N matrix, and is then coupled into an output waveguide for each streamlet to form an output WDM light stream which is detected to generate a product of the vector and matrix. The vector-matrix multiplier can be formed as an integrated optical circuit using either waveguide amplitude modulators or ring resonator amplitude modulators.

  5. Tax Multipliers: Pitfalls in Measurement and Identification

    OpenAIRE

    Daniel Riera-Crichton; Carlos A. Vegh; Guillermo Vuletin

    2012-01-01

    We contribute to the literature on tax multipliers by analyzing the pitfalls in identification and measurement of tax shocks. Our main focus is on disentangling the discussion regarding the identification of exogenous tax policy shocks (i.e., changes in tax policy that are not the result of policymakers responding to output fluctuations) from the discussion related to the measurement of tax policy (i.e., finding a tax policy variable under the direct control of the policymaker). For this purp...

  6. Multiplier-free filters for wideband SAR

    DEFF Research Database (Denmark)

    Dall, Jørgen; Christensen, Erik Lintz

    2001-01-01

    This paper derives a set of parameters to be optimized when designing filters for digital demodulation and range prefiltering in SAR systems. Aiming at an implementation in field programmable gate arrays (FPGAs), an approach for the design of multiplier-free filters is outlined. Design results...... are presented in terms of filter complexity and performance. One filter has been coded in VHDL and preliminary results indicate that the filter can meet a 2 GHz input sample rate....

  7. Mining, regional Australia and the economic multiplier

    Directory of Open Access Journals (Sweden)

    Paul Cleary

    2012-12-01

    Full Text Available Mining in Australia has traditionally delivered a strong development multiplier for regional communities where most mines are based. This relationship has weakened in recent decades as a result of the introduction of mobile workforces - typically known as fly in, fly out. Political parties have responded with policies known as ‘royalties for regions’, though in designing them they overlooked long established Indigenous arrangements for sharing benefits with areas affected directly by mining.

  8. The Uncertainty Multiplier and Business Cycles

    OpenAIRE

    Saijo, Hikaru

    2013-01-01

    I study a business cycle model where agents learn about the state of the economy by accumulating capital. During recessions, agents invest less, and this generates noisier estimates of macroeconomic conditions and an increase in uncertainty. The endogenous increase in aggregate uncertainty further reduces economic activity, which in turn leads to more uncertainty, and so on. Thus, through changes in uncertainty, learning gives rise to a multiplier effect that amplifies business cycles. I use ...

  9. Measurement of CP-violation with the GEM detector

    International Nuclear Information System (INIS)

    Yamamoto, Hiroaki

    1993-01-01

    In this note, the feasibility of measuring CP-violation in the B-meson system with the GEM detector at SSC is described, using the decay mode B d → J/ψ + K 0 S → μ + μ - π + π - for the β angle measurement. In Section 2, the signature of the signal is discussed. Section 3 is devoted to a description of the GEM performance, including the estimation of the backgrounds. The rate of the signal is discussed in Section 4, and the summary is given in Section 5

  10. HydroGEM, a hydrogen fuelled utility vehicle. Case study

    International Nuclear Information System (INIS)

    Hoevenaars, A.J.; Kraaij, G.J.; De Bruijne, M.; Weeda, M.

    2010-02-01

    This report describes the conversion of a Global Electric Motorcars (GEM, a Chrysler company) electric utility vehicle into a Fuel Cell Vehicle called HydroGEM, at the Energy research Centre of the Netherlands (ECN). The report is prepared as a case study within the framework of Task 18 on 'Evaluation of Integrated Hydrogen Systems' of the IEA Hydrogen Implementing Agreement. The vehicle's fuel cell system was designed in 2005, manufactured and built into the vehicle in 2006 and operated from 2007 onwards. The design-choices, assembly, operation and maintenance-issues are presented and discussed.

  11. Isometric multipliers of a vector valued Beurling algebra on a ...

    Indian Academy of Sciences (India)

    Home; Journals; Proceedings – Mathematical Sciences; Volume 127; Issue 1. Isometric multipliers of a vector valued Beurling algebra on a discrete semigroup. Research Article Volume 127 Issue 1 February 2017 pp 109- ... Keywords. Weighted semigroup; multipliers of a semigroup; Beurling algebra; isometric multipliers.

  12. Study of heterogeneous multiplying and non-multiplying media by the neutron pulsed source technique

    International Nuclear Information System (INIS)

    Deniz, V.

    1969-01-01

    The pulsed neutron technique consists essentially in sending in the medium to be studied a short neutron pulse and in determining the asymptotic decay constant of the generated population. The variation of the decay constant as a function of the size of the medium allows the medium characteristics to be defined. This technique has been largely developed these last years and has been applied as well to moderator as to multiplying media, in most cases homogeneous ones. We considered of interest of apply this technique to lattices, to see if useful informations could be collected for lattice calculations. We present here a general theoretical study of the problem, and results and interpretation of a series of experiments made on graphite lattices. There is a good agreement for non-multiplying media. In the case of multiplying media, it is shown that the age value used until now in graphite lattices calculations is over-estimated by about 10 per cent [fr

  13. A high reliability automatic multiplier for a mass spectrometer ion detector circuit

    International Nuclear Information System (INIS)

    Hoshino, Kiichi; Satooka, Sakae

    1978-01-01

    An automatic multiplier of an ion detector circuit for measurement of isotopic abundance ratio of heavy hydrogen to be used with a single collector has been constructed. This multiplier works at 1/1, 1/5, 1/20, 1/100, 1/500, 1/2000 and infinity, and the input voltage which is required to change the range from 1/1 to 1/5 is 10 mV and that from 1/2000 to infinity is 20 V. As the amplifier preceding the automatic multiplier, a vibrating reed electrometer which generates maximum output of 30 V is used. On measurement, marks which indicate the magnifications are recorded on the chart of electronic recorder. It is possible to set the minimum magnification at 1/1, 1/5, or 1/20 by a switch for setting the minimum magnification. (author)

  14. Entrepreneurship in Ireland 2012: global entrepreneurship monitor (GEM)

    OpenAIRE

    Fitzsimons, Paula; O'Gorman, Colm

    2013-01-01

    Report on entrepreneurship in Ireland in the year 2012. Data used is the Global Entrepreneurship Monitor (GEM) data for Ireland and selected comparative countries. The report profiles entrepreneurs, reports on the rate of entrepreneurship in Ireland, discusses female entrepreneurship, and positions these results in the context of Irish entrepreneurship policy.

  15. Some Interesting Mathematical Gems -R-ES-ONANCE--Isep-te ...

    Indian Academy of Sciences (India)

    Same thing applies to results cho- sen here" I shall not refer to gems like Godel's incom- plete theorern or the ... ematics, theoretical computer science, probability and statistics. Based on an invited talk dedi- cated to Dr P L Bhatnagar,. Founder Professor of the Math- ematics Department (then known as Department of Ap-.

  16. Hard assets : The return on rare diamonds and gems

    NARCIS (Netherlands)

    Renneboog, L.D.R.; Spaenjers, C.

    2012-01-01

    This note examines the investment performance of diamonds and other gems (sapphires, rubies, and emeralds) over the period 1999–2010, using a novel data set of auction transactions. Over our time frame, the annualized real USD returns for white and colored diamonds equaled 6.4% and 2.9%,

  17. Hard Assets : The Returns on Rare Diamonds and Gems

    NARCIS (Netherlands)

    Renneboog, L.D.R.; Spaenjers, C.

    2011-01-01

    This paper examines the investment performance of diamonds and other gems (sapphires, rubies, and emeralds) over the period 1999-2010, using a novel data set of auction transactions. Between 1999 and 2010, the annualized real USD returns for white and colored diamonds equaled 6.4% and 2.9%,

  18. Hard assets : The return of rare diamonds and gems

    NARCIS (Netherlands)

    Renneboog, Luc; Spaenjers, Christophe; Grynberg, Roman; Mbayi, Letsema

    This note examines the investment performance of diamonds and other gems (sapphires, rubies, and emeralds) over the period 1999–2010, using a novel data set of auction transactions. Over our time frame, the annualized real USD returns for white and colored diamonds equaled 6.4% and 2.9%,

  19. Dijk- en oeverval aan den cal. Willem Annapolder (Gem. Kapelle)

    NARCIS (Netherlands)

    Verhagen, H.J.

    1936-01-01

    Foto's van de aanleg van de dijk- en oeverval aan den cal. Willem Annapolder (Gem. Kapelle) 3. Linkerhelft dijkval Willem Annapolder. 30 Dec. 1936 4. Rechtehelft dijkval Willem Annapolder. 30 Dec. 1936 5. Overzicht dijkval Willem Annaolder. 30 Dec. 1936 6. Kleikisting binnendijks aangebacht. 14/15

  20. The Gravity and Extreme Magnetism Small Explorer (GEMS)

    Science.gov (United States)

    Kallman, T. R.

    2011-01-01

    The Gravity and Extreme Magnetism Small Explorer (GEMS) was selected by NASA for flight in 2014 to make a sensitive search for X-ray polarization from a wide set of source classes, including stellar black holes, Seyfert galaxies and quasars, blazars, rotation and accretion-powered pulsars, magnetars, shell supernova remnants and pulsar wind nebulae. Among the primary scientific objectives are determining the effects of the spin of black holes and the geometry of supermassive black hole accretion, determining the configurations of the magnetic fields and the X-ray emission of magnetars, and determining the magnetic structure of the supernova shocks in which cosmic rays are accelerated. GEMS will observe 23 targets during a 16 month prime mission, in observations that will be able to reach predicted levels of polarization. The mission can be extended to provide a guest observer phase. The GEMS instrument has time projection chamber polarimeters with high 2-10 keV efficiency at the focus of thin foil mirrors. The 4.5 m focal length mirrors will be deployed on an extended boom. The spacecraft with the instrument is rotated with a period of about 10 minutes to enable measurement and correction of systematic errors. A small Bragg reflection soft X-ray experiment takes advantage of this rotation to obtain a measurement at 0.5 keV. The design of the GEMS instrument and the mission, the expected performance and the planned science program will be discussed.

  1. Quality of the spare triple-GEM detectors

    CERN Document Server

    Lenci, Rosario; Paoletti, Emiliano; Pasquali, Luigi; Pinci, Davide; Piscitelli, Carmelo; Poli Lener, Marco; Sciubba, Adalberto; Tskhadadze, Edisher

    2017-01-01

    Triple-GEM chambers equip the inner region of the M1 muon station. In order to provide spare detectors in case of problems in the operating ones, new chambers have been assembled at the Frascati National Laboratories of the INFN. This note summarizes the results of the quality tests performed at the end of the production procedure.

  2. Surface Features and Cathodoluminescence (CL) Characteristics of Corundum Gems from Eastern of Thailand

    Science.gov (United States)

    Boonsoong, A.

    2017-12-01

    Thailand has long been well known as a supplier of gemstones and also one of the world's color stone centers for decades. The principal gemstones are corundum, garnet and zircon. The corundum deposits of Chanthaburi-Trat Provinces form the most significant ruby-sapphire concentration in Thailand. Corundums are commonly found in secondary deposits (alluvium, elluvial, residual-soil and colluvium deposits as well as stream sediments) with the thickness of the gem-bearing layer varying from 10-100cm and the thickness of the overburden ranging up to 15m. A number of corundum samples were collected from each of the twenty-nine corundum deposits in the Chanthaburi-Trat gem fields, eastern of Thailand. Corundum varies in colour across the region with colours associated with three geographic zones; a western zone, characterized by blue, green and yellow sapphires; a middle zone with blue, green sapphires plus rubies; and an eastern zone yielding mainly rubies. This project has aim to study surface features and characterize the Cathodoluminescence (CL) of corundum gems in the Chanthaburi-Trat gem fields, Thailand. Surfaces of the corundums under a scanning electron microscope show triangular etch features and randomly oriented needle-like patterns. These reveal that the corundums have interacted with the magma during their ascent to the Earth's surface. Surface features attributable to transport and weathering processes are scratches, conchoidal fractures and a spongy surface appearance. Clay minerals and Fe-Ti oxide minerals deposited on the spongy surfaces of some corundums also indicate that these grains experienced chemical weathering or reacted with the soil solution while they were in the alluvium. Cathodoluminescence shows some blue sapphires to exhibit dull blue luminescence. The main cause of the CL appearance of sapphires is likely to be a quench centre, Fe2+ in their structure. The bright red luminescence in corundum reflects a high Cr3+ content and is always

  3. Transient phenomena in bounded fast multiplying assemblies

    International Nuclear Information System (INIS)

    Kraft, T.E.

    1976-01-01

    A generalized dispersion formalism is developed in the context of time-, space-, and energy-dependent transport theory. The evolution of the neutron population in a fast multiplying system following an initial burst of neutrons is examined. The generalized dispersion law obtained is an integral equation, in one variable, for the Laplace and Fourier transformed time- and space-dependent sources of fission neutrons. An approximation technique is shown to generate solutions which converge in L 2 norm to the exact solution for exact elastic, exact inelastic, Goertzel-Grueling or Wigner scattering kernels, and any reasonable fission spectrum

  4. Quasiparticle trapping and the quasiparticle multiplier

    International Nuclear Information System (INIS)

    Booth, N.E.

    1987-01-01

    Superconductors and in particular superconducting tunnel junctions can be used to detect phonons, electromagnetic radiation, x rays, and nuclear particles by the mechanism of Cooper-pair breaking to produce excess quasiparticles and phonons. We show that the sensitivity can be increased by a factor of 100 or more by trapping the quasiparticles in another superconductor of lower gap in the region of the tunnel junction. Moreover, if the ratio of the gap energies is >3 a multiplication process can occur due to the interaction of the relaxation phonons. This leads to the concept of the quasiparticle multiplier, a device which could have wider applications than the Gray effect transistor or the quiteron

  5. Multipliers on Generalized Mixed Norm Sequence Spaces

    Directory of Open Access Journals (Sweden)

    Oscar Blasco

    2014-01-01

    Full Text Available Given 1≤p,q≤∞ and sequences of integers (nkk and (nk′k such that nk≤nk′≤nk+1, the generalized mixed norm space ℓℐ(p,q is defined as those sequences (ajj such that ((∑j∈Ik‍|aj|p1/pk∈ℓq where Ik={j∈ℕ0 s.t. nk≤jmultipliers (ℓℐ(r,s,ℓ(u,v, for different sequences ℐ and of intervals in ℕ0, are determined.

  6. Continuous health monitoring of Graphite Epoxy Motorcases (GEM)

    Science.gov (United States)

    Finlayson, Richard D.; Schaafsma, David T.; Shen, H. Warren; Carlos, Mark F.; Miller, Ronnie K.; Shepherd, Brent

    2001-07-01

    Following the explosion of Delta 241 (IIR-1) on January 17th, 1997, the failure investigation board concluded that the Graphite Epoxy Motorcases (GEM's) should be inspected for damage just prior to launch. Subsequent investigations and feedback from industry led to an Aerospace Corporation proposal to instrument the entire fleet of GEM's with a continuous health monitoring system. The period of monitoring would extend from the initial acceptance testing through final erection on the launch pad. As this proposal demonstrates, (along with the increasing use of advanced composite materials in aircraft, automobiles, military hardware, and aerospace components such as rocket motorcases) a sizable need for composite health assessment measures exist. Particularly where continuous monitoring is required for the detection of damage from impacts and other sources of high mechanical and thermal stresses. Even low-momentum impacts can lead to barely visible impact damage (BVID), corresponding to a significant weakening of the composite. This damage, undetectable by visual inspection, can in turn lead to sudden and catastrophic failure when the material is subjected to a normal operating load. There is perhaps no system with as much potential for truly catastrophic failure as a rocket motor. We will present an update on our ongoing efforts with the United States Air Force Delta II Program Office, and The Aerospace Corporation. This will cover the development of a local, portable, surface-mounted, fiberoptic sensor based impact damage monitor designed to operate on a Delta II GEM during transport, storage, and handling. This system is designed to continuously monitor the GEMs, to communicate wirelessly with base stations and maintenance personnel, to operate autonomously for extended periods, and to fit unobtrusively on the GEM itself.

  7. Synthesis of highly faceted multiply twinned gold nanocrystals stabilized by polyoxometalates

    International Nuclear Information System (INIS)

    Yuan Junhua; Chen Yuanxian; Han Dongxue; Zhang Yuanjian; Shen Yanfei; Wang Zhijuan; Niu Li

    2006-01-01

    A novel and facile chemical synthesis of highly faceted multiply twinned gold nanocrystals is reported. The gold nanocrystals are hexagonal in transmission electron microscopy and icosahedral in scanning electron microscopy. Phosphotungstic acid (PTA), which was previously reduced, serves as a reductant and stabilizer for the synthesis of gold nanocrystals. The PTA-gold nanocomposites are quite stable in aqueous solutions, and electrochemically active towards the hydrogen evolution reaction

  8. 3D field calculation of the GEM prototype magnet and comparison with measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lari, R.J.

    1983-10-28

    The proposed 4 GeV Electron Microtron (GEM) is designed to fill the existing buildings left vacant by the demise of the Zero Gradient Synchrotron (ZGS) accelerator. One of the six large dipole magnets is shown as well as the first 10 electron orbits. A 3-orbit prototype magnet has been built. The stepped edge of the magnet is to keep the beam exiting perpendicular to the pole. The end guards that wrap around the main coils are joined together by the 3 shield plates. The auxiliary coils are needed to keep the end guards and shield plates from saturating. A 0.3 cm Purcell filter air gap exists between the pole and the yoke. Can anyone question this being a truly three-dimensional magnetostatic problem. The computer program TOSCA, developed at the Rutherford Appleton Laboratory by the Computing Applications Group, was used to calculate this magnet and the results have been compared with measurements.

  9. 3D field calculation of the GEM prototype magnet and comparison with measurements

    International Nuclear Information System (INIS)

    Lari, R.J.

    1983-01-01

    The proposed 4 GeV Electron Microtron (GEM) is designed to fill the existing buildings left vacant by the demise of the Zero Gradient Synchrotron (ZGS) accelerator. One of the six large dipole magnets is shown as well as the first 10 electron orbits. A 3-orbit prototype magnet has been built. The stepped edge of the magnet is to keep the beam exiting perpendicular to the pole. The end guards that wrap around the main coils are joined together by the 3 shield plates. The auxiliary coils are needed to keep the end guards and shield plates from saturating. A 0.3 cm Purcell filter air gap exists between the pole and the yoke. Can anyone question this being a truly three-dimensional magnetostatic problem. The computer program TOSCA, developed at the Rutherford Appleton Laboratory by the Computing Applications Group, was used to calculate this magnet and the results have been compared with measurements

  10. Analysis of data recorded by the LCTPC equipped with a two layer GEM-system

    CERN Document Server

    Ljunggren, M

    2012-01-01

    wire based readout. The prototype TPC is placed in a 1 Tesla magnet at DESY and tested using an electron beam. Analyses of data taken during two different measurement series, in 2009 and 2010, are presented here. The TPC was instrumented with a two layer GEM system and read out using modified electronics from the ALICE experiment, including the programmable charge sensitive preamp-shaper PCA16. The PCA16 chip has a number of programmable parameters which allows studies to determine the settings optimal to the final TPC. Here, the impact of the shaping time on the space resolution in the drift direction was studied. It was found that a shaping time of 60 ns is the b...

  11. Rhinoplasty for the multiply revised nose.

    Science.gov (United States)

    Foda, Hossam M T

    2005-01-01

    To evaluate the problems encountered on revising a multiply operated nose and the methods used in correcting such problems. The study included 50 cases presenting for revision rhinoplasty after having had 2 or more previous rhinoplasties. An external rhinoplasty approach was used in all cases. Simultaneous septal surgery was done whenever indicated. All cases were followed for a mean period of 32 months (range, 1.5-8 years). Evaluation of the surgical result depended on clinical examination, comparison of pre- and postoperative photographs, and degree of patients' satisfaction with their aesthetic and functional outcome. Functionally, 68% suffered nasal obstruction that was mainly caused by septal deviations and nasal valve problems. Aesthetically, the most common deformities of the upper two thirds of the nose included pollybeak (64%), dorsal irregularities (54%), dorsal saddle (44%), and open roof deformity (42%), whereas the deformities of lower third included depressed tip (68%), tip contour irregularities (60%), and overrotated tip (42%). Nasal grafting was necessary in all cases; usually more than 1 type of graft was used in each case. Postoperatively, 79% of the patients, with preoperative nasal obstruction, reported improved breathing; 84% were satisfied with their aesthetic result; and only 8 cases (16%) requested further revision to correct minor deformities. Revision of a multiply operated nose is a complex and technically demanding task, yet, in a good percentage of cases, aesthetic as well as functional improvement are still possible.

  12. Quantum mechanics in a multiply connected region

    International Nuclear Information System (INIS)

    Miyazawa, H.

    1986-01-01

    It is usually assumed that wave fields or wave functions are single valued functions of space-time. However, the phase of a complex field is an unobservable quantity and there is no obvious reason that it must be single valued. On this point quantum mechanics in a multiply connected regions is not well formulated. This ambiguity appears e.g., in the case of the Bohm-Aharonov effect concerning the observability of the vector potential around a magnetic flux. The author discusses the single or multiple valuedness of wave functions and attempts to see if such an effect really exists or not. The wave function of a charged particle in a multiply connected region is not necessarily single valued. The condition that the ground state energy be a minimum fixes the character of the multiple valuedness. For a charged particle around a magnetic flux a multiple valued wave function is preferable and no Bohm-Aharonov effect is observed. The minimum energy principle is proved if one also considers the interaction of a charged particle with external objects. Then theoretically the Bohm-Aharonov effect should not be observed. Experiments are not yet conclusive on this point

  13. Microchannel electron multiplier: improvement in gain performances and detection dynamics

    International Nuclear Information System (INIS)

    Audier, M.; Delmotte, J.C.; Boutot, J.P.

    1978-01-01

    The performances of an MCP are a function of its geometrical characteristics (diameter d and ratio 1/d of a channel, useful area) and of the applied voltage. Gain and mean output current are limited by saturation phenomena. By using a particular cascaded MCP's configuration, it is possible to simultaneously improve the gain, its associated fluctuations and the detection dynamics (detected level, counting rate). For gains 10 6 7 , the fluctuations, can be kept as low as 20% and an improvement by a factor > 10 can be obtained on the detection dynamics [fr

  14. Hadamard Multipliers and Abel Dual of Hardy Spaces

    Directory of Open Access Journals (Sweden)

    Paweł Mleczko

    2016-01-01

    Full Text Available The paper is devoted to the study of Hadamard multipliers of functions from the abstract Hardy classes generated by rearrangement invariant spaces. In particular the relation between the existence of such multiplier and the boundedness of the appropriate convolution operator on spaces of measurable functions is presented. As an application, the description of Hadamard multipliers into H∞ is given and the Abel type theorem for mentioned Hardy spaces is proved.

  15. φ-Multipliers on Banach Algebras and Topological Modules

    OpenAIRE

    Adib, Marjan

    2015-01-01

    We prove some results concerning Arens regularity and amenability of the Banach algebra ${M}_{\\phi }(A)$ of all $\\phi $ -multipliers on a given Banach algebra $A$ . We also consider $\\phi $ -multipliers in the general topological module setting and investigate some of their properties. We discuss the $\\phi $ -strict and $\\phi $ -uniform topologies on ${M}_{\\phi }(A)$ . A characterization of $\\phi $ -multipliers on ${L}_{1}(G)$ -module ${L}_{p}(G)$ , where $G$ is a compact group, is given.

  16. Neutron multiplier alternative for fusion reactor blankets

    International Nuclear Information System (INIS)

    Taczanowski, S.

    1980-01-01

    A proposal is given to replace neutron multiplier needed to enable low lithium and tritium inventories simultaneously assuring sufficient production of tritium, by an efficient moderator ( 7 LiH or 7 LiD). The advantageous effect of the intensified neutron energy degradation is due to the 1/v character of the main tritium producing reaction. The slowing-down medium is designed to be the source of moderated neutrons for the surrounding Li ( 6 Li enriched) region where the most of tritium is to be produced. The surplus tritium production remains stored in the moderator zone. Some preliminary calculations illustrating the above concept were carried out and the neutron flux and tritium production distributions are presented. The indications regarding further studies are also suggested. (author)

  17. Four-gate transistor analog multiplier circuit

    Science.gov (United States)

    Mojarradi, Mohammad M. (Inventor); Blalock, Benjamin (Inventor); Cristoloveanu, Sorin (Inventor); Chen, Suheng (Inventor); Akarvardar, Kerem (Inventor)

    2011-01-01

    A differential output analog multiplier circuit utilizing four G.sup.4-FETs, each source connected to a current source. The four G.sup.4-FETs may be grouped into two pairs of two G.sup.4-FETs each, where one pair has its drains connected to a load, and the other par has its drains connected to another load. The differential output voltage is taken at the two loads. In one embodiment, for each G.sup.4-FET, the first and second junction gates are each connected together, where a first input voltage is applied to the front gates of each pair, and a second input voltage is applied to the first junction gates of each pair. Other embodiments are described and claimed.

  18. GEM1: First-year modeling and IT activities for the Global Earthquake Model

    Science.gov (United States)

    Anderson, G.; Giardini, D.; Wiemer, S.

    2009-04-01

    GEM is a public-private partnership initiated by the Organisation for Economic Cooperation and Development (OECD) to build an independent standard for modeling and communicating earthquake risk worldwide. GEM is aimed at providing authoritative, open information about seismic risk and decision tools to support mitigation. GEM will also raise risk awareness and help post-disaster economic development, with the ultimate goal of reducing the toll of future earthquakes. GEM will provide a unified set of seismic hazard, risk, and loss modeling tools based on a common global IT infrastructure and consensus standards. These tools, systems, and standards will be developed in partnership with organizations around the world, with coordination by the GEM Secretariat and its Secretary General. GEM partners will develop a variety of global components, including a unified earthquake catalog, fault database, and ground motion prediction equations. To ensure broad representation and community acceptance, GEM will include local knowledge in all modeling activities, incorporate existing detailed models where possible, and independently test all resulting tools and models. When completed in five years, GEM will have a versatile, penly accessible modeling environment that can be updated as necessary, and will provide the global standard for seismic hazard, risk, and loss models to government ministers, scientists and engineers, financial institutions, and the public worldwide. GEM is now underway with key support provided by private sponsors (Munich Reinsurance Company, Zurich Financial Services, AIR Worldwide Corporation, and Willis Group Holdings); countries including Belgium, Germany, Italy, Singapore, Switzerland, and Turkey; and groups such as the European Commission. The GEM Secretariat has been selected by the OECD and will be hosted at the Eucentre at the University of Pavia in Italy; the Secretariat is now formalizing the creation of the GEM Foundation. Some of GEM's global

  19. Faster Double-Size Bipartite Multiplication out of Montgomery Multipliers

    Science.gov (United States)

    Yoshino, Masayuki; Okeya, Katsuyuki; Vuillaume, Camille

    This paper proposes novel algorithms for computing double-size modular multiplications with few modulus-dependent precomputations. Low-end devices such as smartcards are usually equipped with hardware Montgomery multipliers. However, due to progresses of mathematical attacks, security institutions such as NIST have steadily demanded longer bit-lengths for public-key cryptography, making the multipliers quickly obsolete. In an attempt to extend the lifespan of such multipliers, double-size techniques compute modular multiplications with twice the bit-length of the multipliers. Techniques are known for extending the bit-length of classical Euclidean multipliers, of Montgomery multipliers and the combination thereof, namely bipartite multipliers. However, unlike classical and bipartite multiplications, Montgomery multiplications involve modulus-dependent precomputations, which amount to a large part of an RSA encryption or signature verification. The proposed double-size technique simulates double-size multiplications based on single-size Montgomery multipliers, and yet precomputations are essentially free: in an 2048-bit RSA encryption or signature verification with public exponent e=216+1, the proposal with a 1024-bit Montgomery multiplier is at least 1.5 times faster than previous double-size Montgomery multiplications.

  20. Efek Multiplier Zakat terhadap Pendapatan di Provinsi DKI Jakarta

    OpenAIRE

    Al Arif, M. Nur Rianto

    2012-01-01

    The aim of this research is to analyse the multiplier effect of zakâh revenue in DKI Jakarta. A study case at Badan Amil Zakat, Infak, and Sadaqah (BAZIS) DKI Jakarta. Least square method is used to analyze the data. The coefficients will be used to calculate the multiplier effect of zakâh-revenue and it will be compared with the economy without zakah revenue. The results showed 2,522 multiplier effects of zakâh-revenue and 3.561 multiplier effect ofeconomic income without zakâh-revenue. Thi...

  1. The determination of the orbit of the Japanese satellite Ajisai and the GEM-T1 and GEM-T2 gravity field models

    Science.gov (United States)

    Sanchez, Braulio V.

    1990-01-01

    The Japanese Experimental Geodetic Satellite Ajisai was launched on August 12, 1986. In response to the TOPEX-POSEIDON mission requirements, the GSFC Space Geodesy Branch and its associates are producing improved models of the Earth's gravitational field. With the launch of Ajisai, precise laser data is now available which can be used to test many current gravity models. The testing of the various gravity field models show improvements of more than 70 percent in the orbital fits when using GEM-T1 and GEM-T2 relative to results obtained with the earlier GEM-10B model. The GEM-T2 orbital fits are at the 13-cm level (RMS). The results of the tests with the various versions of the GEM-T1 model indicate that the addition of satellite altimetry and surface gravity anomalies as additional data types should improve future gravity field models.

  2. GEMS: Underwater spectrometer for long-term radioactivity measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sartini, Ludovica, E-mail: ludovica.sartini@ingv.i [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sect.Roma 2, Roma (Italy); Genoa University, Genoa (Italy); Simeone, Francesco; Pani, Priscilla [' Sapienza' University and Istituto Nazionale di Fisica Nucleare (INFN), Sect.Roma, Roma (Italy); Lo Bue, Nadia; Marinaro, Giuditta [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sect.Roma 2, Roma (Italy); Grubich, Andry; Lobko, Alexander [Institute for Nuclear Problems (INP), Belarus State University, Minsk (Belarus); Etiope, Giuseppe [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sect.Roma 2, Roma (Italy); Capone, Antonio [' Sapienza' University and Istituto Nazionale di Fisica Nucleare (INFN), Sect.Roma, Roma (Italy); Favali, Paolo [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sect.Roma 2, Roma (Italy); Gasparoni, Francesco; Bruni, Federico [Tecnomare S.p.A., Venice (Italy)

    2011-01-21

    GEMS (Gamma Energy Marine Spectrometer) is a prototype of an autonomous radioactivity sensor for underwater measurements, developed in the framework for a development of a submarine telescope for neutrino detection (KM3NeT Design Study Project). The spectrometer is highly sensitive to gamma rays produced by {sup 40}K decays but it can detect other natural (e.g., {sup 238}U,{sup 232}Th) and anthropogenic radio-nuclides (e.g., {sup 137}Cs). GEMS was firstly tested and calibrated in the laboratory using known sources and it was successfully deployed for a long-term (6 months) monitoring at a depth of 3200 m in the Ionian Sea (Capo Passero, offshore Eastern Sicily). The instrument recorded data for the whole deployment period within the expected specifications. This monitoring provided, for the first time, a continuous time-series of radioactivity in deep-sea.

  3. Development of a GEM-based high rate TPC

    Energy Technology Data Exchange (ETDEWEB)

    Neubert, Sebastian; Hoeppner, Christian; Ketzer, Bernhard; Weitzel, Quirin; Paul, Stefan; Woerner, Lisa; Konorov, Igor; Mann, Alexander [Technische Universitaet Muenchen, Physik Department E18, Garching (Germany)

    2008-07-01

    A TPC is considered as the central tracker of the PANDA experiment, which is currently being planned at the new accelerator complex FAIR at Darmstadt. PANDA is designed as an internal target experiment at the antiproton storage ring HESR. The central tracker has to measure particle trajectories over a wide momentum range (0.1-8 GeV/c) from up to 2.10{sup 7} antiproton-proton annihilations/s. The continuous nature of the antiproton beam makes the use of a traditional ion gate impractical. Owing to their intrinsic ion suppression properties, GEM foils are planned as the amplification stage. A small prototype of this GEM-TPC (diameter 200 mm, drift length 77 mm) has been built and characterized with cosmic muons. Results such as spatial resolution, cluster distributions, and diffusion properties are presented in this talk.

  4. Development of a GEM-based TPC for PANDA

    Energy Technology Data Exchange (ETDEWEB)

    Hoeppner, Christian; Ketzer, Bernhard; Konorov, Igor; Mann, Alexander; Neubert, Sebastian; Paul, Stephan; Weitzel, Quirin; Woerner, Lisa [Technische Universitaet Muenchen, Physik Department E18, 85748 Garching (Germany)

    2008-07-01

    A TPC is considered as the central tracker of the PANDA experiment, which is currently being planned at the new accelerator complex FAIR at Darmstadt. PANDA is designed as an internal target experiment at the antiproton storage ring HESR. The central tracker has to measure particle trajectories over a wide momentum range (0.1-8 GeV/c) from up to 2.10{sup 7} antiproton-proton annihilations/s. The continuous nature of the antiproton beam makes the use of a traditional ion gate impractical. Owing to their intrinsic ion suppression properties, GEM foils are planned as the amplification stage. A small prototype of this GEM-TPC (diameter 200 mm, drift length 77 mm) has been built and characterized with cosmic muons. Results such as spatial resolution, cluster distributions, and diffusion properties are presented in this talk.

  5. A triple GEM gamma camera for medical application

    Energy Technology Data Exchange (ETDEWEB)

    Anulli, F. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Balla, A. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Bencivenni, G. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Corradi, G. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); D' Ambrosio, C. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Domenici, D. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Felici, G. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Gatta, M. [Laboratori Nazionali di Frascati INFN, Frascati (Italy); Morone, M.C. [Dipartimento di Biopatologia e Diagnostica per immagini, Universita di Roma Tor Vergata (Italy); INFN - Sezione di Roma Tor Vergata (Italy); Murtas, F. [Laboratori Nazionali di Frascati INFN, Frascati (Italy)]. E-mail: fabrizio.murtas@lnf.infn.it; Schillaci, O. [Dipartimento di Biopatologia e Diagnostica per immagini, Universita di Roma Tor Vergata (Italy)

    2007-03-01

    A Gamma Camera for medical applications 10x10cm{sup 2} has been built using a triple GEM chamber prototype. The photon converters placed in front of the three GEM foils, has been realized with different technologies. The chamber, High Voltage supplied with a new active divider made in Frascati, is readout through 64 pads, 1mm{sup 2} wide, organized in a row of 8cm long, with LHCb ASDQ chip. This Gamma Camera can be used both for X-ray movie and PET-SPECT imaging; this chamber prototype is placed in a scanner system, creating images of 8x8cm{sup 2}. Several measurements have been performed using phantom and radioactive sources of Tc99m(140keV) and Na22(511keV). Results on spatial resolution and image reconstruction are presented.

  6. The R + D transfer in Spain: diagnostic based 2006 GEM

    International Nuclear Information System (INIS)

    Coduras Martinez, A.; Urbano Pulido, D.; Ruiz Navarro, J.

    2007-01-01

    The main purpose of this research is to analyse in the international context the situation today of the Spanish R and D transference from the scientific field to the firms, using 2006 GEM data as well as complementary data sources. The main findings of the study emphasize a difficult scenario concerning the R and D transference to the Spanish enterprises. Although these negative results, some data suggest a significant improvement in this area in the near future. (Author) 9 refs

  7. Serial data acquisition for GEM-2D detector

    International Nuclear Information System (INIS)

    Kolasinski, Piotr; Pozniak, Krzysztof T.; Czarski, Tomasz; Linczuk, Maciej; Byszuk, Adrian; Chernyshova, Maryna; Juszczyk, Bartlomiej; Kasprowicz, Grzegorz; Wojenski, Andrzej; Zabolotny, Wojciech; Zienkiewicz, Pawel; Mazon, Didier; Malard, Philippe; Herrmann, Albrecht; Vezinet, Didier

    2014-01-01

    This article debates about data fast acquisition and histogramming method for the X-ray GEM detector. The whole process of histogramming is performed by FPGA chips (Spartan-6 series from Xilinx). The results of the histogramming process are stored in an internal FPGA memory and then sent to PC. In PC data is merged and processed by MATLAB. The structure of firmware functionality implemented in the FPGAs is described. Examples of test measurements and results are presented. (authors)

  8. Combined readout of a triple-GEM detector

    Science.gov (United States)

    Antochi, V. C.; Baracchini, E.; Cavoto, G.; Di Marco, E.; Marafini, M.; Mazzitelli, G.; Pinci, D.; Renga, F.; Tomassini, S.; Voena, C.

    2018-05-01

    Optical readout of GEM based devices by means of high granularity and low noise CMOS sensors allows to obtain very interesting tracking performance. Space resolution of the order of tens of μm were measured on the GEM plane along with an energy resolution of 20%÷30%. The main limitation of CMOS sensors is represented by their poor information about time structure of the event. In this paper, the use of a concurrent light readout by means of a suitable photomultiplier and the acquisition of the electric signal induced on the GEM electrode are exploited to provide the necessary timing informations. The analysis of the PMT waveform allows a 3D reconstruction of each single clusters with a resolution on z of 100 μm. Moreover, from the PMT signals it is possible to obtain a fast reconstruction of the energy released within the detector with a resolution of the order of 25% even in the tens of keV range useful, for example, for triggering purpose.

  9. A refined gravity model from Lageos /GEM-L2/

    Science.gov (United States)

    Lerch, F. J.; Klosko, S. M.; Patel, G. B.

    1982-01-01

    Lageos satellite laser ranging (SLR) data taken over a 2.5 yr period were employed to develop the Goddard Earth Model GEM-L2, a refined gravity field model. Additional data was gathered with 30 other satellites, resulting in spherical harmonics through degree and order 20, based on over 600,000 measurements. The Lageos data was accurate down to 10 cm, after which the GEM 9 data were used to make adjustments past order 7. The resolution of long wavelength activity, through degree and order 4, was made possible by the Lageos data. The GEM-L2 model features a 20 x 20 geopotential, tracking station coordinates (20), 5-day polar motion and A1-UT1 values, and a GM value of 398,600.607 cu km/sq sec. The accuracy of station positioning has been raised to within 6 cm total position globally and within 1.8 cm in baselines. It is concluded that SLR is useful for measuring tectonic plate motions and inter-plate deformations.

  10. Modelling Chemical Equilibrium Partitioning with the GEMS-PSI Code

    Energy Technology Data Exchange (ETDEWEB)

    Kulik, D.; Berner, U.; Curti, E

    2004-03-01

    Sorption, co-precipitation and re-crystallisation are important retention processes for dissolved contaminants (radionuclides) migrating through the sub-surface. The retention of elements is usually measured by empirical partition coefficients (Kd), which vary in response to many factors: temperature, solid/liquid ratio, total contaminant loading, water composition, host-mineral composition, etc. The Kd values can be predicted for in-situ conditions from thermodynamic modelling of solid solution, aqueous solution or sorption equilibria, provided that stoichiometry, thermodynamic stability and mixing properties of the pure components are known (Example 1). Unknown thermodynamic properties can be retrieved from experimental Kd values using inverse modelling techniques (Example 2). An efficient, advanced tool for performing both tasks is the Gibbs Energy Minimization (GEM) approach, implemented in the user-friendly GEM-Selector (GEMS) program package, which includes the Nagra-PSI chemical thermodynamic database. The package is being further developed at PSI and used extensively in studies relating to nuclear waste disposal. (author)

  11. Modelling Chemical Equilibrium Partitioning with the GEMS-PSI Code

    International Nuclear Information System (INIS)

    Kulik, D.; Berner, U.; Curti, E.

    2004-01-01

    Sorption, co-precipitation and re-crystallisation are important retention processes for dissolved contaminants (radionuclides) migrating through the sub-surface. The retention of elements is usually measured by empirical partition coefficients (Kd), which vary in response to many factors: temperature, solid/liquid ratio, total contaminant loading, water composition, host-mineral composition, etc. The Kd values can be predicted for in-situ conditions from thermodynamic modelling of solid solution, aqueous solution or sorption equilibria, provided that stoichiometry, thermodynamic stability and mixing properties of the pure components are known (Example 1). Unknown thermodynamic properties can be retrieved from experimental Kd values using inverse modelling techniques (Example 2). An efficient, advanced tool for performing both tasks is the Gibbs Energy Minimization (GEM) approach, implemented in the user-friendly GEM-Selector (GEMS) program package, which includes the Nagra-PSI chemical thermodynamic database. The package is being further developed at PSI and used extensively in studies relating to nuclear waste disposal. (author)

  12. Is Kyoto Fatally Flawed? An Analysis with MacGEM

    International Nuclear Information System (INIS)

    Eyckmans, J.; Van Regemorter, D.; Van Steenberghe, V.

    2002-06-01

    In this paper we present some numerical simulations with the MacGEM model to evaluate the consequences of the recent Marrakesh agreements and the defection of the USA for the Kyoto Protocol. MacGEM is a global marginal abatement cost model for carbon emissions from fossil fuel use based on the GEM-E3-World general equilibrium. Nonparticipation of the USA causes the equilibrium carbon price in Annex B countries to fall by approximately 50% since an important share of permit demand falls out. Carbon sinks enhancement activities enable Parties to fulfil their reduction commitment at lower compliance costs and cause the equilibrium permit price to decrease by 40%. Finally, it is shown that the former Soviet Union and central European countries have substantial monopoly power in the Kyoto carbon permit market. We conclude that the recent accords have eroded completely the Kyoto Protocol's emission targets but that they have the merit to have saved the international climate change negotiation framework

  13. Triple-GEM detectors for the innermost region of the muon apparatus at the LHCb experiment

    CERN Document Server

    Poli-Lener, M; Bencivenni, G

    2005-01-01

    The LHCb experiment will take place at the future LHC accelerator at CERN and will start in 2007. It is a single arm spectrometer to precision measurements of CP violation and rare decays in the b quark sector. Recent experimental results have shown that CP violation is large in this sector. LHCb is designed with a robust and flexible trigger in order to extensively gain access to a wide spread of different physical processes involving the beauty particles. This will allow to over-constrain the Standard Model predictions about $\\mathcal{CP}$ violation, and to discover any possible inconsistency, which would reveal the presence of ''New Physics''. The work presented in this thesis has two main parts: the development of a charged particle detector based on Gas Electron Multiplication (GEM) and the study of luminosity measurements with the physical channels $Z^{0} \\rightarrow \\mu^{+} \\mu^{-}$ and $W^{\\pm} \\rightarrow \\mu^{\\pm} \

  14. First tests of thick GEMs with electrodes made of a resistive kapton

    International Nuclear Information System (INIS)

    Oliveira, R.; Peskov, V.; Pietropaolo, F.; Picchi, P.

    2007-01-01

    We have developed a new design of a GEM-like detector with electrodes made of a resistive kapton. This detector can operate at gains close to 10 5 even in pure noble gases (Ar and Ne) and if transited to discharges at higher gains, due to the high resistivity of electrodes, they do not damage either the detector or the front-end electronics. Gains ∼10 6 can be achieved in a cascaded mode of operation. The detector can operate without gain degradation at counting rates of at least up to 10 4 Hz/cm 2 and it could thus be very useful in many applications requiring safe high-gain operation, for example, in RICH, TPCs, and calorimetry

  15. Encoding Schemes For A Digital Optical Multiplier Using The Modified Signed-Digit Number Representation

    Science.gov (United States)

    Lasher, Mark E.; Henderson, Thomas B.; Drake, Barry L.; Bocker, Richard P.

    1986-09-01

    The modified signed-digit (MSD) number representation offers full parallel, carry-free addition. A MSD adder has been described by the authors. This paper describes how the adder can be used in a tree structure to implement an optical multiply algorithm. Three different optical schemes, involving position, polarization, and intensity encoding, are proposed for realizing the trinary logic system. When configured in the generic multiplier architecture, these schemes yield the combinatorial logic necessary to carry out the multiplication algorithm. The optical systems are essentially three dimensional arrangements composed of modular units. Of course, this modularity is important for design considerations, while the parallelism and noninterfering communication channels of optical systems are important from the standpoint of reduced complexity. The authors have also designed electronic hardware to demonstrate and model the combinatorial logic required to carry out the algorithm. The electronic and proposed optical systems will be compared in terms of complexity and speed.

  16. Multiplier method may be unreliable to predict the timing of temporary hemiepiphysiodesis for coronal angular deformity.

    Science.gov (United States)

    Wu, Zhenkai; Ding, Jing; Zhao, Dahang; Zhao, Li; Li, Hai; Liu, Jianlin

    2017-07-10

    The multiplier method was introduced by Paley to calculate the timing for temporary hemiepiphysiodesis. However, this method has not been verified in terms of clinical outcome measure. We aimed to (1) predict the rate of angular correction per year (ACPY) at the various corresponding ages by means of multiplier method and verify the reliability based on the data from the published studies and (2) screen out risk factors for deviation of prediction. A comprehensive search was performed in the following electronic databases: Cochrane, PubMed, and EMBASE™. A total of 22 studies met the inclusion criteria. If the actual value of ACPY from the collected date was located out of the range of the predicted value based on the multiplier method, it was considered as the deviation of prediction (DOP). The associations of patient characteristics with DOP were assessed with the use of univariate logistic regression. Only one article was evaluated as moderate evidence; the remaining articles were evaluated as poor quality. The rate of DOP was 31.82%. In the detailed individual data of included studies, the rate of DOP was 55.44%. The multiplier method is not reliable in predicting the timing for temporary hemiepiphysiodesis, even though it is prone to be more reliable for the younger patients with idiopathic genu coronal deformity.

  17. Multipliers for the Absolute Euler Summability of Fourier Series

    Indian Academy of Sciences (India)

    In this paper, the author has investigated necessary and sufficient conditions for the absolute Euler summability of the Fourier series with multipliers. These conditions are weaker than those obtained earlier by some workers. It is further shown that the multipliers are best possible in certain sense.

  18. Multiplier convergent series and uniform convergence of mapping ...

    Indian Academy of Sciences (India)

    MS received 14 April 2011; revised 17 November 2012. Abstract. In this paper, we introduce the frame property of complex sequence sets and study the uniform convergence of nonlinear mapping series in β-dual of spaces consisting of multiplier convergent series. Keywords. Multiplier convergent series; mapping series. 1.

  19. Dimension of the c-nilpotent multiplier of Lie algebras

    Indian Academy of Sciences (India)

    Abstract. The purpose of this paper is to derive some inequalities for dimension of the c-nilpotent multiplier of finite dimensional Lie algebras and their factor Lie algebras. We further obtain an inequality between dimensions of c-nilpotent multiplier of Lie algebra L and tensor product of a central ideal by its abelianized factor ...

  20. Silicon Photo-Multiplier Radiation Hardness Tests with a White Neutron Beam

    International Nuclear Information System (INIS)

    Montanari, A.; Tosi, N.; Pietropaolo, A.; Andreotti, M.; Baldini, W.; Calabrese, R.; Cibinetto, G.; Luppi, E.; Cotta Ramusino, A.; Malaguti, R.; Santoro, V.; Tellarini, G.; Tomassetti, L.; De Donato, C.; Reali, E.

    2013-06-01

    We report radiation hardness tests performed, with a white neutron beam, at the Geel Electron Linear Accelerator in Belgium on silicon Photo-Multipliers. These are semiconductor photon detectors made of a square matrix of Geiger-Mode Avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to about 6.2 x 10 9 1-MeV-equivalent neutrons per cm 2 . (authors)

  1. Charge exchange and ionization in atom-multiply-charged ion collisions

    International Nuclear Information System (INIS)

    Presnyakov, L.P.; Uskov, D.B.

    1988-01-01

    This study investigates one-electron transitions to the continuous and discrete spectra induced by a collision of atom A and multiply-charged ion B +Z with nuclear charge Z > 3. An analytical method is developed the charge-exchange reaction; this method is a generalization of the decay model and the approximation of nonadiabatic coupling of two states that are used as limiting cases in the proposed approach

  2. Influence of capture to excited states of multiply charged ion beams colliding with small molecules

    International Nuclear Information System (INIS)

    Montenegro, P; Monti, J M; Fojón, O A; Hanssen, J; Rivarola, R D

    2015-01-01

    Electron capture by multiply charged ions impacting on small molecules is theoretically investigated. Particular attention is paid to the case of biological targets. The interest is focused on the importance of the transition to excited final states which can play a dominant role on the total capture cross sections. Projectiles at intermediate and high collision energies are considered. Comparison with existing experimental data is shown. (paper)

  3. Optimizing strassen matrix multiply on GPUs

    KAUST Repository

    ul Hasan Khan, Ayaz; Al-Mouhamed, Mayez; Fatayer, Allam

    2015-01-01

    © 2015 IEEE. Many core systems are basically designed for applications having large data parallelism. Strassen Matrix Multiply (MM) can be formulated as a depth first (DFS) traversal of a recursion tree where all cores work in parallel on computing each of the NxN sub-matrices that reduces storage at the detriment of large data motion to gather and aggregate the results. We propose Strassen and Winograd algorithms (S-MM and W-MM) based on three optimizations: a set of basic algebra functions to reduce overhead, invoking efficient library (CUBLAS 5.5), and parameter-tuning of parametric kernel to improve resource occupancy. On GPUs, W-MM and S-MM with one recursion level outperform CUBLAS 5.5 Library with up to twice as faster for large arrays satisfying N>=2048 and N>=3072, respectively. Compared to NVIDIA SDK library, S-MM and W-MM achieved a speedup between 20x to 80x for the above arrays. The proposed approach can be used to enhance the performance of CUBLAS and MKL libraries.

  4. Optimizing strassen matrix multiply on GPUs

    KAUST Repository

    ul Hasan Khan, Ayaz

    2015-06-01

    © 2015 IEEE. Many core systems are basically designed for applications having large data parallelism. Strassen Matrix Multiply (MM) can be formulated as a depth first (DFS) traversal of a recursion tree where all cores work in parallel on computing each of the NxN sub-matrices that reduces storage at the detriment of large data motion to gather and aggregate the results. We propose Strassen and Winograd algorithms (S-MM and W-MM) based on three optimizations: a set of basic algebra functions to reduce overhead, invoking efficient library (CUBLAS 5.5), and parameter-tuning of parametric kernel to improve resource occupancy. On GPUs, W-MM and S-MM with one recursion level outperform CUBLAS 5.5 Library with up to twice as faster for large arrays satisfying N>=2048 and N>=3072, respectively. Compared to NVIDIA SDK library, S-MM and W-MM achieved a speedup between 20x to 80x for the above arrays. The proposed approach can be used to enhance the performance of CUBLAS and MKL libraries.

  5. ICFA Instrumentation Bulletin, Volume 17, Fall 1998 Issue (SLAC-J-ICFA-017)

    Energy Technology Data Exchange (ETDEWEB)

    Va' Vra, J.

    2003-10-20

    The authors study the operation of the Gas Electron Multiplier (GEM) is pure Ar, in comparison to that in Ar-CO{sub 2} mixture. In pure Ar, high GEM gains, of above 700 and 3000 for single and double GEM structures correspondingly, have been obtained. It is observed that the GEM effective gain and its charging-up are strongly affected by electric field values above and below the GEM. Applications to the development of non-aging gas photomultiplier are discussed.

  6. Electronic structure of elements and compounds and electronic phases of solids

    International Nuclear Information System (INIS)

    Nadykto, B.A.

    2000-01-01

    The paper reviews technique and computed energies for various electronic states of many-electron multiply charged ions, molecular ions, and electronic phases of solids. The model used allows computation of the state energy for free many-electron multiply charged ions with relative accuracy ∼10 -4 suitable for analysis of spectroscopy data

  7. Design of two easily-testable VLSI array multipliers

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, J.; Shen, J.P.

    1983-01-01

    Array multipliers are well-suited to VLSI implementation because of the regularity in their iterative structure. However, most VLSI circuits are very difficult to test. This paper shows that, with appropriate cell design, array multipliers can be designed to be very easily testable. An array multiplier is called c-testable if all its adder cells can be exhaustively tested while requiring only a constant number of test patterns. The testability of two well-known array multiplier structures are studied. The conventional design of the carry-save array multipler is shown to be not c-testable. However, a modified design, using a modified adder cell, is generated and shown to be c-testable and requires only 16 test patterns. Similar results are obtained for the baugh-wooley two's complement array multiplier. A modified design of the baugh-wooley array multiplier is shown to be c-testable and requires 55 test patterns. The implementation of a practical c-testable 16*16 array multiplier is also presented. 10 references.

  8. International Genetically Engineered Machine (iGEM) Competition

    CSIR Research Space (South Africa)

    Sparrow, RW

    2010-07-01

    Full Text Available . At this meeting it was requested that the CSIR act as the administrative co-ordinating arm of the team. Following from this meeting a brochure was produced advertising the iGEM competition inside Wits and for Honours student nominations to be team members.... The academic year in South Africa commences in February. By late February 2010 student nominations had been received from which the supervisors selected the team members. The first team meeting was held on 5th March 2010. After which the team...

  9. Study on Physical Properties and Chemical Composition of Some Myanmar Gems

    International Nuclear Information System (INIS)

    Kyaw Myint Htoo; Tun Khin; Sein Htoon

    2004-05-01

    Physical properties of some Myanmar gems were studied by using refractometer, dichroscope, polariscope, SG test, UV test and microscope. Then, chemical composition were investigated by XRF-technique. After that, gem identification, evaluation, colour improvement were studied according to these physical properties and chemical composition

  10. Gain limits of a Thick GEM in high-purity Ne, Ar and Xe

    CERN Document Server

    Miyamoto, J; Peskov, V

    2010-01-01

    The dependence of the avalanche charge gain in Thick Gas Electron Multipliers (THGEM) on the purity of Ne, Ar and Xe filling gases was investigated. The gain, measured with alpha-particles in standard conditions (atmospheric pressure, room temperature), was found to considerably drop in gases purified by non-evaporable getters. On the other hand, small N2 admixtures to noble gases resulted in high reachable gains. The results are of general relevance in the operation of gas-avalanche detectors in noble gases, particularly that of two-phase cryogenic detectors for rare events.

  11. Possible Gems and Ultra-Fine Grained Polyphase Units in Comet Wild 2.

    Science.gov (United States)

    Gainsforth, Z.; Butterworth, A. L.; Jilly-Rehak, C. E.; Westphal, A. J.; Brownlee, D. E.; Joswiak, D.; Ogliore, R. C.; Zolensky, M. E.; Bechtel, H. A.; Ebel, D. S.; hide

    2016-01-01

    GEMS and ultrafine grained polyphase units (UFG-PU) in anhydrous IDPs are probably some of the most primitive materials in the solar system. UFG-PUs contain nanocrystalline silicates, oxides, metals and sulfides. GEMS are rounded approximately 100 nm across amorphous silicates containing embedded iron-nickel metal grains and sulfides. GEMS are one of the most abundant constituents in some anhydrous CPIDPs, often accounting for half the material or more. When NASA's Stardust mission returned with samples from comet Wild 2 in 2006, it was thought that UFG-PUs and GEMS would be among the most abundant materials found. However, possibly because of heating during the capture process in aerogel, neither GEMS nor UFG-PUs have been clearly found.

  12. Gain uniformity experimental study performed on triple-GEM gas detector

    International Nuclear Information System (INIS)

    Dong Liyuan; Qi Huirong; Lu Xinyu; Ouyang Qun; Chen Yuanbo; Li Yuhong

    2012-01-01

    With the application of the two-dimensional GEM gaseous detector in X-ray imaging, the correction method of gain uniformity caused by triple-GEM avalanche structures and electric field uniformity should be studied. The paper reported the study of the triple-GEM detector with effective area 100 mm × 100 mm used the Pad's size of 9.5 mm × 9.5 mm. In the test, 100 readout channels were designed. Results showed that gain remained stable over time; at air flow increases, gain from increases obviously to changes very little. Particularly, triple-GEM's gain uniformity was very good (more than 80%) and the range of energy resolution was from 0.18 to 0.2. To improve gain consistency of results, the difference value revised was obtained to be about 0.1 by the least square method. It provided a better method to improve gain uniformity of GEM detector. (authors)

  13. Analytical theory of frequency-multiplying gyro-traveling-wave-tubes

    International Nuclear Information System (INIS)

    Nusinovich, G.S.; Chen, W.; Granatstein, V.L.

    2001-01-01

    The theory is developed which describes analytically the gain and bandwidth in frequency-multiplying gyro-traveling-wave-tubes. In this theory the input waveguide is considered in the small-signal approximation. Then, in the drift region separating the input and output waveguides, the electron ballistic bunching evolves which causes the appearance in the electron current density of the harmonics of the signal frequency. The excitation of the output waveguide by one of these harmonics is considered in a specified current approximation. This makes the analytical study of a large-signal operation possible. The theory is illustrated by using it to analyze the performance of an existing experimental tube

  14. The 2.3 GHz continuum survey of the GEM project

    Science.gov (United States)

    Tello, C.; Villela, T.; Torres, S.; Bersanelli, M.; Smoot, G. F.; Ferreira, I. S.; Cingoz, A.; Lamb, J.; Barbosa, D.; Perez-Becker, D.; Ricciardi, S.; Currivan, J. A.; Platania, P.; Maino, D.

    2013-08-01

    Context. Determining the spectral and spatial characteristics of the radio continuum of our Galaxy is an experimentally challenging endeavour for improving our understanding of the astrophysics of the interstellar medium. This knowledge has also become of paramount significance for cosmology, since Galactic emission is the main source of astrophysical contamination in measurements of the cosmic microwave background (CMB) radiation on large angular scales. Aims: We present a partial-sky survey of the radio continuum at 2.3GHz within the scope of the Galactic Emission Mapping (GEM) project, an observational program conceived and developed to reveal the large-scale properties of Galactic synchrotron radiation through a set of self-consistent surveys of the radio continuum between 408MHz and 10GHz. Methods: The GEM experiment uses a portable and double-shielded 5.5-m radiotelescope in altazimuthal configuration to map 60-degree-wide declination bands from different observational sites by circularly scanning the sky at zenithal angles of 30° from a constantly rotating platform. The observations were accomplished with a total power receiver, whose front-end high electron mobility transistor (HEMT) amplifier was matched directly to a cylindrical horn at the prime focus of the parabolic reflector. The Moon was used to calibrate the antenna temperature scale and the preparation of the map required direct subtraction and destriping algorithms to remove ground contamination as the most significant source of systematic error. Results: We used 484 h of total intensity observations from two locations in Colombia and Brazil to yield 66% sky coverage from to . The observations in Colombia were obtained with a horizontal HPBW of and a vertical HPBW of . The pointing accuracy was and the RMS sensitivity was 11.42 mK. The observations in Brazil were obtained with a horizontal HPBW of and a vertical HPBW of . The pointing accuracy was and the RMS sensitivity was 8.24 mK. The zero

  15. Gaseous elemental mercury (GEM) fluxes over canopy of two typical subtropical forests in south China

    Science.gov (United States)

    Yu, Qian; Luo, Yao; Wang, Shuxiao; Wang, Zhiqi; Hao, Jiming; Duan, Lei

    2018-01-01

    Mercury (Hg) exchange between forests and the atmosphere plays an important role in global Hg cycling. The present estimate of global emission of Hg from natural source has large uncertainty, partly due to the lack of chronical and valid field data, particularly for terrestrial surfaces in China, the most important contributor to global atmospheric Hg. In this study, the micrometeorological method (MM) was used to continuously observe gaseous elemental mercury (GEM) fluxes over forest canopy at a mildly polluted site (Qianyanzhou, QYZ) and a moderately polluted site (Huitong, HT, near a large Hg mine) in subtropical south China for a full year from January to December in 2014. The GEM flux measurements over forest canopy in QYZ and HT showed net emission with annual average values of 6.67 and 0.30 ng m-2 h-1, respectively. Daily variations of GEM fluxes showed an increasing emission with the increasing air temperature and solar radiation in the daytime to a peak at 13:00, and decreasing emission thereafter, even as a GEM sink or balance at night. High temperature and low air Hg concentration resulted in the high Hg emission in summer. Low temperature in winter and Hg absorption by plant in spring resulted in low Hg emission, or even adsorption in the two seasons. GEM fluxes were positively correlated with air temperature, soil temperature, wind speed, and solar radiation, while it is negatively correlated with air humidity and atmospheric GEM concentration. The lower emission fluxes of GEM at the moderately polluted site (HT) when compared with that in the mildly polluted site (QYZ) may result from a much higher adsorption fluxes at night in spite of a similar or higher emission fluxes during daytime. This shows that the higher atmospheric GEM concentration at HT restricted the forest GEM emission. Great attention should be paid to forests as a crucial increasing Hg emission source with the decreasing atmospheric GEM concentration in polluted areas because of Hg

  16. Confinement of multiply charged ions in an ECRH mirror plasma

    International Nuclear Information System (INIS)

    Petty, C.C.

    1989-06-01

    This thesis is an experimental study of multiply charged ions in the Constance B mirror experiment. By measuring the ion densities, end loss fluxes and ion temperatures, the parallel confinement times for the first five charge states of oxygen and neon plasmas are determined. The parallel ion confinement times increase with charge state and peak on axis, both indications of an ion-confining potential dip created by the hot electrons. The radial profile of ion end loss is usually hollow due to large ion radial transport (τ paralleli ∼ τ perpendiculari ), with the peak fluxes occurring at the edge of the electron cyclotron resonance zone. Several attempts are made to increase the end loss of selected ion species. Using minority ICRH, the end loss flux of resonant ions increases by 20% in cases when radial transport induced by ICRH is not too severe. A large antenna voltage can also extinguish the plasma. By adding helium to an oxygen plasma, the end loss of O 6+ increases by 80% due to decreased ion radial transport. An ion model is developed to predict the ion densities, end loss fluxes and confinement times in the plasma center using the ion particle balance equations, the quasineutrality condition and theoretical confinement time formulas. The model generally agrees with the experimental data for oxygen and neon plasmas to within experimental error. Under certain conditions spatial diffusion appears to determine the parallel ion confinement time of the highest charge states. For oxygen plasmas during ICRH, the measured parallel confinement time of the resonant ions is much shorter than their theoretical value, probably due to rf diffusion of the ions into the loss cone. 58 refs., 101 figs., 16 tabs

  17. The Gem Infrasound Logger and Custom-Built Instrumentation

    International Nuclear Information System (INIS)

    Anderson, Jacob F.; Ronan, Timothy J.

    2017-01-01

    Here, we designed, built, and recorded data with a custom infrasound logger (referred to as the Gem) that is inexpensive, portable, and easy to use. We also describe its design process, qualities, and applications in this article. Field instrumentation is a key element of geophysical data collection, and the quantity and quality of data that can be recorded is determined largely by the characteristics of the instruments used. Geophysicists tend to rely on commercially available instruments, which suffice for many important types of fieldwork. However, commercial instrumentation can fall short in certain roles, which motivates the development of custom sensors and data loggers. Particularly, we found existing data loggers to be expensive and inconvenient for infrasound campaigns, and developed the Gem infrasound logger in response. In this article, we discuss development of this infrasound logger and the various uses found for it, including projects on volcanoes, high-altitude balloons, and rivers. Further, we demonstrate that when needed, scientists can feasibly design and build their own specialized instruments, and that doing so can enable them to record more and better data at a lower cost.

  18. An overview of current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes

    CERN Document Server

    Gys, Thierry

    1999-01-01

    Current developments in position-sensitive hybrid photon detectors and photo-multiplier tubes have stimulated increased interest from a variety of fields such as astronomy, biomedical imaging and high- energy physics. These devices are sensitive to single photons over a photon energy spectrum defined by the transmission of the optical entrance window and the photo-cathode type. Their spatial resolution ranges from a few millimeters for pad hybrid photon detectors and multi-anode photo-multiplier tubes down to a few tens of microns for pixel hybrid photon detectors and electron-bombarded charge-coupled devices. Basic technological and design aspects are assessed in this paper. (21 refs).

  19. Photoionization of multiply charged ions at the advanced light source

    International Nuclear Information System (INIS)

    Schlachter, A.S.; Kilcoyne, A.L.D.; Aguilar, A.; Gharaibeh, M.F.; Emmons, E.D.; Scully, S.W.J.; Phaneuf, R.A.; Muller, A.; Schippers, S.; Alvarez, I.; Cisneros, C.; Hinojosa, G.; McLaughlin, B.M.

    2004-01-01

    Photoionization of multiply charged ions is studied using the merged-beams technique at the Advanced Light Source. Absolute photoionization cross sections have been measured for a variety of ions along both isoelectronic and isonuclear sequences

  20. Cavallo's multiplier for in situ generation of high voltage

    Science.gov (United States)

    Clayton, S. M.; Ito, T. M.; Ramsey, J. C.; Wei, W.; Blatnik, M. A.; Filippone, B. W.; Seidel, G. M.

    2018-05-01

    A classic electrostatic induction machine, Cavallo's multiplier, is suggested for in situ production of very high voltage in cryogenic environments. The device is suitable for generating a large electrostatic field under conditions of very small load current. Operation of the Cavallo multiplier is analyzed, with quantitative description in terms of mutual capacitances between electrodes in the system. A demonstration apparatus was constructed, and measured voltages are compared to predictions based on measured capacitances in the system. The simplicity of the Cavallo multiplier makes it amenable to electrostatic analysis using finite element software, and electrode shapes can be optimized to take advantage of a high dielectric strength medium such as liquid helium. A design study is presented for a Cavallo multiplier in a large-scale, cryogenic experiment to measure the neutron electric dipole moment.

  1. Sociophysics of sexism: normal and anomalous petrie multipliers

    Science.gov (United States)

    Eliazar, Iddo

    2015-07-01

    A recent mathematical model by Karen Petrie explains how sexism towards women can arise in organizations where male and female are equally sexist. Indeed, the Petrie model predicts that such sexism will emerge whenever there is a male majority, and quantifies this majority bias by the ‘Petrie multiplier’: the square of the male/female ratio. In this paper—emulating the shift from ‘normal’ to ‘anomalous’ diffusion—we generalize the Petrie model to a stochastic Poisson model that accommodates heterogeneously sexist men and woman, and that extends the ‘normal’ quadratic Petrie multiplier to ‘anomalous’ non-quadratic multipliers. The Petrie multipliers span a full spectrum of behaviors which we classify into four universal types. A variation of the stochastic Poisson model and its Petrie multipliers is further applied to the context of cyber warfare.

  2. Atomic collisions in fusion plasmas involving multiply charged ions

    International Nuclear Information System (INIS)

    Salzborn, E.

    1980-01-01

    A short survey is given on atomic collisions involving multiply charged ions. The basic features of charge transfer processes in ion-ion and ion-atom collisions relevant to fusion plasmas are discussed. (author)

  3. Efek Multiplier Zakat Terhadap Pendapatan di Propinsi DKI Jakarta

    Directory of Open Access Journals (Sweden)

    M. Nur Rianto Al Arif

    2015-10-01

    Full Text Available The aim of this research is to analyze the multiplier effect of zakah revenue in DKI Jakarta, a study case at Badan Amil Zakat, Infak, and Shadaqah (BAZIS DKI Jakarta. Least square methods is used to analyze the data. The coefficient will be used to calculate the multiplier effect of zakah revenue and it will be compared with the economy without zakah revenue. The result showed 2,522 multiplier effects of zakah revenue and 3,561 multiplier effect of economic income without zakah revenue. This suggest that the management of zakah in BAZIS DKI Jakarta still can have a significant influence on the economyDOI: 10.15408/aiq.v4i1.2079

  4. Multiplier less high-speed squaring circuit for binary numbers

    Science.gov (United States)

    Sethi, Kabiraj; Panda, Rutuparna

    2015-03-01

    The squaring operation is important in many applications in signal processing, cryptography etc. In general, squaring circuits reported in the literature use fast multipliers. A novel idea of a squaring circuit without using multipliers is proposed in this paper. Ancient Indian method used for squaring decimal numbers is extended here for binary numbers. The key to our success is that no multiplier is used. Instead, one squaring circuit is used. The hardware architecture of the proposed squaring circuit is presented. The design is coded in VHDL and synthesised and simulated in Xilinx ISE Design Suite 10.1 (Xilinx Inc., San Jose, CA, USA). It is implemented in Xilinx Vertex 4vls15sf363-12 device (Xilinx Inc.). The results in terms of time delay and area is compared with both modified Booth's algorithm and squaring circuit using Vedic multipliers. Our proposed squaring circuit seems to have better performance in terms of both speed and area.

  5. Instructional Computing Project Uses "Multiplier Effect" to Train Florida Teachers.

    Science.gov (United States)

    Roblyer, M. D.; Castine, W. H.

    1987-01-01

    Reviews the efforts undertaken in the Florida Model Microcomputer Trainer Project (FMMTP) and its statewide impact. Outlines its procedural strategies, trainer curriculum, networking system, and the results of its multiplier effect. (ML)

  6. EFEK MULTIPLIER ZAKAT TERHADAP PENDAPATAN DI PROVINSI DKI JAKARTA

    Directory of Open Access Journals (Sweden)

    M. Nur Rianto Al Arif

    2016-02-01

    Full Text Available The aim of this research is to analyse the multiplier effect of zakâh revenue in DKI Jakarta. A study case at Badan Amil Zakat, Infak, and Sadaqah (BAZIS DKI Jakarta. Least square method is used to analyze the data. The coefficients will be used to calculate the multiplier effect of zakâh-revenue and it will  be compared with the economy without zakah revenue. The results showed 2,522 multiplier effects of zakâh-revenue and 3.561 multiplier effect ofeconomic income without zakâh-revenue. This suggests that the management of zakat in BAZIS Jakarta still can have a significant influence on the economy.DOI: 10.15408/aiq.v4i1.2533

  7. The generalization of the Schur multipliers of Bieberbach groups

    Science.gov (United States)

    Masri, Rohaidah; Hassim, Hazzirah Izzati Mat; Sarmin, Nor Haniza; Ali, Nor Muhainiah Mohd; Idrus, Nor'ashiqin Mohd

    2014-12-01

    The Schur multiplier is the second homology group of a group. It has been found to be isomorphic to the kernel of a homomorphism which maps the elements in the exterior square of the group to the elements in its derived subgroup. Meanwhile, a Bieberbach group is a space group which is a discrete cocompact group of isometries of oriented Euclidean space. In this research, the Schur multipliers of Bieberbach groups with cyclic point group of order two of finite dimension are computed.

  8. Physics of subcritical multiplying regions and experimental validation

    International Nuclear Information System (INIS)

    Salvatores, M.

    1996-01-01

    The coupling of a particle accelerator with a spallation target and with a subcritical multiplying region has been proposed in the fifties and is called here a hybrid system. This article gives some ideas about the energetic balance of such a system. The possibilities of experimental validation of some properties of a subcritical multiplying region by using MASURCA facility at CEA-Cadarache are examined. The results of a preliminary experiment called MUSE are presented. (A.C.)

  9. Isometric multipliers of a vector valued Beurling algebra on a ...

    Indian Academy of Sciences (India)

    Throughout, let S be a nonunital faith- ful abelian semigroup, and let A be a commutative Banach algebra. A map σ : S → S is a multiplier [1, 4] if σ(xy) = xσ(y) = σ(x)y, x,y ∈ S. Let M(S) be the set of all multipliers of S. Then M(S) is a unital abelian semigroup under composition. Since S is faithful, S can be imbedded as an ...

  10. A micro-TCA based data acquisition system for the Triple-GEM detectors for the upgrade of the CMS forward muon spectrometer

    CERN Document Server

    Lenzi, Thomas

    2016-01-01

    We will present the electronic and DAQ system being developed for TripleGEM detectors which will be installed in the CMS muon spectrometer. The microTCA system uses an Advanced Mezzanine Card equipped with an FPGA and the Versatile Link with the GBT chipset to link the front and back-end. On the detector an FPGA mezzanine board, the OptoHybrid, has to collect the data from the detector readout chips to transmit them optically to the microTCA boards using the GBT protocol. We will describe the hardware architecture, report on the status of the developments, and present results obtained with the system.In this contribution we will report on the progress of the design of the electronic readout and data acquisition (DAQ) system being developed for Triple-GEM detectors which will be installed in the forward region (1.5 < eta < 2.2) of the CMS muon spectrometer during the 2nd long shutdown of the LHC, planed for the period 2018-2019. The architecture of the Triple-GEM readout system is based on the use of the...

  11. Development of the data acquisition system for the Triple-GEM detectors for the upgrade of the CMS forward muon spectrometer

    CERN Document Server

    Abbaneo, D; Akl, M A; Ahmed, W; Armaingaud, C; Aspell, P; Assran, Y; Bally, S; Ban, Y; Banerjee, S; Barria, P; Benussi, L; Bhopatkar, V; Bianco, S; Bos, J; Bouhali, O; Cai, J; Calabria, C; Castaneda, A; Cauwenbergh, S; Celik, A; Christiansen, J; Colafranceschi, S; Colaleo, A; Conde Garcia, A; Dabrowski, M; De Lentdecker, G; De Oliveira, R; De Robertis, G; Dildick, S; Ferry, S; Flanagan, W; Gilmore, J; Guilloux, F; Gutierrez, A; Hoepfner, K; Hohlmann, M; Kamon, T; Karchin, P E; Khotilovich, V; Korntheuer, M; Krutelyov, S; Lenzi, T; Loddo, F; Maerschalk, T; Magazzu, G; Maggi, M; Maghrbi, Y; Marchioro, A; Marinov, A; Mazumdar, N; Merlin, J A; Mukhopadhyay, S; Nuzzo, S; Oliveri, E; Philipps, B; Piccolo, D; Postema, H; Radi, A; Radogna, R; Raffone, G; Ranieri, A; Rodrigues, A; Ropelewski, L; Safonov, A; Sakharov, A; Salva, S; Saviano, G; Sharma, A; Talvitie, J; Tatarinov, A; Teng, H; Turini, N; Tuuva, T; Twigger, J; Tytgat, M; van Stenis, M.; Verhagen, E; Yang, Y; Zaganidis, N; Zenoni, F

    2014-01-01

    In this contribution we will report on the progress of thedesign of the readout and data acquisition system being developedfor triple-GEM detectors which will be installed in the forwardregion (1.5 < |η| < 2.2) of the CMS muonspectrometer during the 2nd long shutdown of the LHC, expectedin the period 2017–2018. The system will be designed to take fulladvantage of current generic developments introduced for the LHCupgrades. The current design is based on the use of CERN GLIB boardshosted in micro-TCA crates for the off-detector electronics and theVersatile Link with the GBT chipset to link the front-endelectronics to the GLIB boards. In this contribution we willdescribe the physics goals, the hardware architectures and report onthe expected performance of the CMS GEM readout system, includingpreliminary timing resolution simulations.

  12. Cluster-assistant generation of multiply charged atomic ions in nanosecond laser ionization of seeded methyl iodide beam

    International Nuclear Information System (INIS)

    Luo Xiaolin; Niu Dongmei; Kong Xianglei; Wen Lihua; Liang Feng; Pei Kemei; Wang Bin; Li Haiyang

    2005-01-01

    The photoionization of methyl iodide beam seeded in argon and helium is studied by time-of-flight mass spectrometry using a 25 ns, 532 nm Nd-YAG laser with intensities in the range of 2 x 10 10 -2 x 10 11 W/cm 2 . Multiply charged ions of I q+ (q = 2-3) and C 2+ with tens of eV kinetic energies have been observed when laser interacts with the middle part of the pulsed molecular beam, whose peak profiles are independent on the laser polarization directions. Strong evidences show that these ions are coming from the Coulomb explosion of multiply charged CH 3 I clusters, and laser induced inverse bremsstrahlung absorption of caged electrons plays a key role in the formation of multiply charged ions

  13. Features of destruction of solids by laser radiation in process of formation of multiply charged ions

    International Nuclear Information System (INIS)

    Bedilov, R.M.; Bedilov, M.R.; Sabitov, M.M.; Matnazarov, A.; Niyozov, B.

    2004-01-01

    Full text: It is known, under interaction of laser radiation with solid surface a power density q > 0.01 W/cm 2 are observed destruction of a solid and issue of electrons, ions, neutrals, neutrons, plasmas, and also radiation in a wide ranges of a spectra. Despite of a plenty of works, devoted to study of processes of interaction, the studies of feature of destruction of solids by laser beam in process of formation multiply charged ions are insufficiently investigated. The results of study feature of destruction of solids by laser radiation in process of formation multiply charged ions are given in this work. In our experiments, we used the mass spectrometer with single-channel laser radiation. The laser installation had the following parameters: a power density of laser radiation q=(0.1-50) GW/cm 2 ; the angle of incidence a=18 deg. to the target surface Al, (W). It was obtained experimentally dynamics of morphology of destruction and also mass - charge and energy spectra of multiply charged ions formed under interaction of laser radiation with Al (W) in the intensity range q=(0.1-50) GW/cm 2 . These studies showed features of destruction Al(W) by laser radiation, i.e. invariable of value evaporation mass from a surface of a solid increase as the laser intensity q. But thus temperature a pair increases in accordance with increase of flow density of a laser radiation. Increase of temperature the pair gives in formation of multiply charged plasma. It is typical that, as q of the laser increases the maximum charge number of ions in laser plasma considerably increase and their energy spectra extend toward higher energies. For example, under q=0.1 GW/cm 2 and 50 GW/cm 2 the maximum charge number of ions Al (W) are equal to Z max = 1 and 7, respectively. From the experimental data obtained, we can conclude that, the formed multiply charged plasma practically completely absorption laser radiation and 'shielding' a target surface for various metals at power densities

  14. Research of boron conversion coating in neutron detector with boron deposited GEM

    International Nuclear Information System (INIS)

    Ye Di; Sun Zhijia; Zhou Jianrong; Wang Yanfeng; Yang Guian; Xu Hong; Chen Yuanbai; Xiao Yu; Diao Xungang

    2014-01-01

    GEM is a flourishing new gas detector and nowadays its technology become more mature. It has outstanding properties, such as excellent position resolution, high counting rate, radiation resistance, simple and flexible signal readout, can be large-area detector, wide application range. Detector with boron deposited GEM uses multilayer GEM with deposited boron film as neutron conversion carrier which reads out the information of neutron shot from the readout electrode with gas amplification from every GEM layer. The detector is high performance which can meet the demands of neutron detector of a new generation. Boron deposited neutron conversion electrode with boron deposited cathode and GEM included is the core part of the detector. As boron is a high-melting-point metalloid (> 2 000 ℃), electroplating and thermal evaporation are inappropriate ways. So finding a way to deposit boron on electrode which can meet the demands become a key technology in the development of neutron detector with boron deposited GEM. Compared with evaporation, sputtering has features such as low deposition temperature, high film purity, nice adhesive, thus is appropriate for our research. Magnetron sputtering is a improved way of sputtering which can get lower sputtering air pressure and higher target voltage, so that we can get better films. Through deposit process, the research uses magnetron sputtering to deposit pure boron film on copper electrode and GEM film. This method can get high quality, nice adhere, high purity, controllable uniformity, low cost film with high speed film formation. (authors)

  15. Reactivity worth of gas expansion modules (GEMs) in the fast flux test facility

    International Nuclear Information System (INIS)

    Campbell, L.R.; Nelson, J.V.; Burke, T.M.; Rawlins, J.A.; Daughtry, J.W.; Bennett, R.A.

    1986-01-01

    A new passive shutdown device called a gas expansion module (GEM) has been developed at Hanford Engineering Development Laboratory to insert negative reactivity during a primary system loss of flow in a liquid-metal reactor (LMR). A GEM is a hollow removable core component which is sealed at the top and open at the bottom. An argon gas bubble trapped inside the assembly expands when core inlet pressure decreases (caused by a flow reduction) and expels sodium from the assembly. The GEMs are designed so that the level of the liquid-sodium primary system coolant within a GEM is above the top of the core when the primary pumps are operating at full flow and is below the bottom of the core when the primary pumps are off. When a GEM is placed at the boundary of the core and radial reflector, the drop in sodium level increases core neutron leakage and inserts negative reactivity. The results of these measurements confirm the effectiveness of GEMs in adding negative reactivity in loss-of-flow situations. It follows, therefore, that the inherent safety of LMRs, comparable in size to the FFTF, can be enhanced by the use of GEMs

  16. Modeling Photo-multiplier Gain and Regenerating Pulse Height Data for Application Development

    Science.gov (United States)

    Aspinall, Michael D.; Jones, Ashley R.

    2018-01-01

    Systems that adopt organic scintillation detector arrays often require a calibration process prior to the intended measurement campaign to correct for significant performance variances between detectors within the array. These differences exist because of low tolerances associated with photo-multiplier tube technology and environmental influences. Differences in detector response can be corrected for by adjusting the supplied photo-multiplier tube voltage to control its gain and the effect that this has on the pulse height spectra from a gamma-only calibration source with a defined photo-peak. Automated methods that analyze these spectra and adjust the photo-multiplier tube bias accordingly are emerging for hardware that integrate acquisition electronics and high voltage control. However, development of such algorithms require access to the hardware, multiple detectors and calibration source for prolonged periods, all with associated constraints and risks. In this work, we report on a software function and related models developed to rescale and regenerate pulse height data acquired from a single scintillation detector. Such a function could be used to generate significant and varied pulse height data that can be used to integration-test algorithms that are capable of automatically response matching multiple detectors using pulse height spectra analysis. Furthermore, a function of this sort removes the dependence on multiple detectors, digital analyzers and calibration source. Results show a good match between the real and regenerated pulse height data. The function has also been used successfully to develop auto-calibration algorithms.

  17. Low-order-mode harmonic multiplying gyrotron traveling-wave amplifier in W band

    International Nuclear Information System (INIS)

    Yeh, Y. S.; Chen, C. H.; Yang, S. J.; Lai, C. H.; Lin, T. Y.; Lo, Y. C.; Hong, J. W.; Hung, C. L.; Chang, T. H.

    2012-01-01

    Harmonic multiplying gyrotron traveling-wave amplifiers (gyro-TWAs) allow for magnetic field reduction and frequency multiplication. To avoid absolute instabilities, this work proposes a W-band harmonic multiplying gyro-TWA operating at low-order modes. By amplifying a fundamental harmonic TE 11 drive wave, the second harmonic component of the beam current initiates a TE 21 wave to be amplified. Absolute instabilities in the gyro-TWA are suppressed by shortening the interaction circuit and increasing wall losses. Simulation results reveal that compared with Ka-band gyro-TWTs, the lower wall losses effectively suppress absolute instabilities in the W-band gyro-TWA. However, a global reflective oscillation occurs as the wall losses decrease. Increasing the length or resistivity of the lossy section can reduce the feedback of the oscillation to stabilize the amplifier. The W-band harmonic multiplying gyro-TWA is predicted to yield a peak output power of 111 kW at 98 GHz with an efficiency of 25%, a saturated gain of 26 dB, and a bandwidth of 1.6 GHz for a 60 kV, 7.5 A electron beam with an axial velocity spread of 8%.

  18. Study and optimization of the light-yield of a triple-GEM detector

    CERN Document Server

    Campagnola, Roberto; Mazzitelli, Giovanni

    The high-resolution tracking of low energy release particles had a remarkable development in recent years and will give a crucial contribution in different fields, from medical uses to those in dark matter search. Characteristics, such as high space and time resolution, low material budget, large volumes, low costs, make gas detectors ideal candidates for this type of devices. A very promising technique involves the optical reading of the light produced by the de-excitation of gas molecules during the processes of electron multiplication. This type of detector has been made possible thanks to the great progresses achieved in last years in the performance in micro pattern gas detector and in the evolution of the CMOS technology which led to the production of sensors able of offering high sensitivity and granularity combined with a very low noise level. In this thesis the performance of a prototype where the light is produced through the multiplication of electrons in a triple GEM structure and acquired by a c...

  19. Alu Mobile Elements: From Junk DNA to Genomic Gems

    Directory of Open Access Journals (Sweden)

    Sami Dridi

    2012-01-01

    Full Text Available Alus, the short interspersed repeated sequences (SINEs, are retrotransposons that litter the human genomes and have long been considered junk DNA. However, recent findings that these mobile elements are transcribed, both as distinct RNA polymerase III transcripts and as a part of RNA polymerase II transcripts, suggest biological functions and refute the notion that Alus are biologically unimportant. Indeed, Alu RNAs have been shown to control mRNA processing at several levels, to have complex regulatory functions such as transcriptional repression and modulating alternative splicing and to cause a host of human genetic diseases. Alu RNAs embedded in Pol II transcripts can promote evolution and proteome diversity, which further indicates that these mobile retroelements are in fact genomic gems rather than genomic junks.

  20. Lingua(gem sob duas perspectivas teóricas

    Directory of Open Access Journals (Sweden)

    Lidiomar José Mascarello

    2010-02-01

    Destacaremos nesse breve percurso teórico dois olhares possíveis para esse fenômeno, a língua(gem, que é tão natural e ao mesmo tempo tão complexo de ser explicado e entendido. De um lado, questões psíquicas individuais, como um processo evolutivo que opera em escala de tempo e que depende da maturação dos processos neurais e de toda rede neuronial e da capacidade inata do sujeito, ou seja, uma visão com tendências mais cognitivista, e por outro, da exposição à interação sócio-ambiental, de cunho interacionista, pois, acreditamos que são complementares e não restritivas ou excludentes.

  1. GEM 10B Satellite gravity data and Nigerian oil prospects

    International Nuclear Information System (INIS)

    Garde, S.C.; Kim, W.Y.

    1984-11-01

    Extension of the hydrocarbon rich Benue depression and the Niger delta basin in the bight of Benin is construed from the gravity data of Gravity Earth Model (GEM) 10B Satellite, published by NASA, Godard Space Flight Centre in 1977. This interpretation is based on the supposition that: i) the depth of a buried horizontal cylinder can be estimated by the Fourier transform of the vertical gravity field [Odegard and Berg, Geophys., 30, No. 3, 424-438 (1965)]; and ii) the oil horizons of southern Nigeria are basically connected to the separation of South American and African plates [Burke et al., African Geology, Ibadan Univ. Press, Ibadan, Nigeria, p. 187-204 (1970)]. (author)

  2. Quench and protection characteristics of the GEM test coil

    International Nuclear Information System (INIS)

    Chaniotakis, E.A.; Marston, P.G.

    1994-01-01

    The GEM test coil, will be wound from 70 m of conductor identical to that used in the full scale magnet. The coil configuration will duplicate the field distribution of the full scale magnet and current control will duplicate full scale current decay characteristics. Therefore, quench/protection analysis of this coil will reveal very important information about the behavior of the full scale model. Due to the uncertainty associated with the contact between the cable, the conduit and the sheath, a parametric analysis has been performed in order to determine and bracket the behavior. With no electrical contact the quench evolves normally until, due to heat transfer from the sheath into the cable, the superconductor temperature becomes critical and the entire length becomes normal

  3. Overview of the GEM muon system cosmic ray test program at the SSCL

    International Nuclear Information System (INIS)

    Milner, E.C.

    1993-04-01

    Muon track resolution exceeding 75-μm per plane is one of the main strengths of the GEM detector design, and will be crucial in searches for Higgs Bosons, heavy Z-Bosons, technicolor, and supersymmetry. Achieving this resolution coal requires improved precision in muon chambers and their alignment. A cosmic ray test stand known as the Texas Test Rio, (TTR) has been created at the SSCL for studying candidate GEM muon chamber technologies. Test results led to selecting Cathode Strip Chambers (CSC) as the GEM muon system baseline chamber technology

  4. Synthesis and Biological Evaluation of Glycosidase Inhibitors: gem-Difluoromethylenated Nojirimycin Analogues

    DEFF Research Database (Denmark)

    Bols, Mikael; Wang, Ruo-Wen; Qiu, Xiao-Long

    2006-01-01

    In our ongoing program aimed at the design, synthesis, and biological evaluation of novel gem-difluoromethylenated glycosidase inhibitors, gem-4,4-difluoromethylenated iminosugars (5-9) were synthesized. The biological evaluation of these synthetic iminosugars showed that the gem....... It is proposed that the unprotonated iminosugar is the species preferably bound by beta-glucosidase, due to the lower pK(a) value of iminosugar 6 than of 1 or 36, leaving iminosugars 1 and 36 mostly protonated at pH 5.0, while iminosugar 6 is not. Iminosugar 6 also displayed good and selective inhibition of beta...

  5. The development of neutron detectors for the GEM instrument at ISIS

    International Nuclear Information System (INIS)

    Rhodes, N.J.; Johnson, M.W.; Schooneveld, E.M.

    2001-01-01

    GEM is a new General Materials diffractometer now being commissioned at ISIS. To meet its broad based scientific programme GEM requires a large area position sensitive detector which covers a wide range of scattering angles and exhibits a high neutron count rate stability. This paper discusses the design of a ZnS/ 6 Li fibre coupled detector array that meets the GEM requirements. Typical detector characteristics are documented together with the current status of the project. Two thirds of the detector array are operational and from the results obtained to date it is already obvious that the impact of this instrument on neutron scattering studies will be profound. (author)

  6. Control and supervision of a time projection chamber with GEM readout

    International Nuclear Information System (INIS)

    Kaiser, David

    2014-01-01

    To get a deeper understanding of the structure of nucleons and the strong interaction binding the constituents inside, the CBELSA/TAPS experiment investigates the resonance spectrum of baryons by meson photoproduction within the scope of the SFB/TRR 16 ''Subnuclear Structure of Matter''. In order to support and expand the physical program, the existing Inner Detector will be replaced by a Time Projection Chamber (TPC) within the next few years. This allows for the detection of charged reaction channels, which can't be measured with the CBELSA/TAPS experiment up to now, as well as for particle identification from the specific energy loss. A First prototype with GEM foils for charge amplification in front of the readout plane and suitable size for the CBELSA/TAPS experiment was built in collaboration with the TU Munich, the detector laboratory of the GSI in Darmstadt and the Stefan-Meyer-Institute of the University Vienna. The TPC has been commissioned successfully within the FOPI experiment at the GSI during several test beam campaigns. Additionally, systematic studies have been carried out with a smaller Test-TPC using a TestBench providing an accurate external track definition. As the electron drift velocity in the TPC volume is a crucial parameter for the exact track reconstruction, detailed simulations of the drift velocity and its dependency on external parameters, such as drift voltage, pressure, gas flow or temperature, have been carried out. The results of these simulations recommend a constant monitoring of all examined parameters to allow a reasonable use of the simulated drift velocities. For this purpose, and to ensure a safe and stable operation of the TPCs and the other detectors on the TestBench, the required hardware, the control software based on a data base and a graphical user interface were designed and constructed as the main part of this work. With this so-called SlowControl, it was possible to measure, control and store several parameters - e

  7. Tables of compound-discount interest rate multipliers for evaluating forestry investments.

    Science.gov (United States)

    Allen L. Lundgren

    1971-01-01

    Tables, prepared by computer, are presented for 10 selected compound-discount interest rate multipliers commonly used in financial analyses of forestry investments. Two set of tables are given for each of the 10 multipliers. The first set gives multipliers for each year from 1 to 40 years; the second set gives multipliers at 5-year intervals from 5 to 160 years....

  8. Development of a triple GEM readout module for a time projection chamber and measurement accuracies of hadronic Higgs branching fractions in ννH at a 350 GeV ILC

    International Nuclear Information System (INIS)

    Mueller, Felix

    2016-07-01

    The presented thesis addresses the development and evaluation of one of the detector concept for the International Linear Collider (ILC). The ILC is a planned, future electron-positron linear collider with a center-of-mass energy of up to 500 GeV in its first construction stage. The ILC is designed to perform precision measurements of the Standard Model, especially a model-independent reconstruction of the electroweak symmetry breaking sector. In 2012, the discovery of the Higgs boson at the LHC was an important first step and facilitates precision measurements of the Higgs boson coupling constants at the ILC. Challenging design goals have been defined for the ILC detectors in order to reach the desired measurement precisions. One of the two ILC detector concepts is the International Large Detector (ILD). A large Time Projection Chamber (TPC) is foreseen as the central tracking detector. In contrast to modern silicon tracking detectors, a TPC provides a large number of space points, and thus continuous sampling of the track parameters. Therefore, TPCs offer great pattern recognition capabilities including the identification of particle decays within the sensitive volume. The design momentum resolution of the ILD TPC is δ(1/p t )∼10 -4 GeV -1 which can be translated into a transverse spatial resolution of σ rφ ≤100 μm over the complete drift distance of 2.35 m. In the first part of the thesis, the development of a readout module for the TPC is presented which fulfills the performance requirements of the ILD TPC. The developed readout module is based on a stack of three ''Gas Electron Multiplier'' (GEM) foils and a pad readout. Thin ceramic grids are used as the support structure and spacers between the GEMs. The readout module was tested in a prototype TPC with a maximal drift distance of around 60 cm at the DESY II test beam. An additional guard ring at the upper edge of the module was introduced to minimize field distortions at the

  9. On centralized power pool auction: a novel multipliers stabilization procedure

    International Nuclear Information System (INIS)

    Jimenez-Redondo, Noemi

    2005-01-01

    This paper addresses the Short-Term Hydro-Thermal Coordination (STHTC) problem. It is a large-scale, combinatorial and nonlinear optimization problem. It is usually solved using a Lagrangian Relaxation (LR) approach. LR procedure is based on the solution of the dual problem of the original one. The dual problem variables are the Lagrange multipliers. These multipliers have an economic meaning: electric energy hourly prices. This paper focuses on an efficient solution of the dual problem of the STHTC problem. A novel multiplier stabilization technique, which significantly improves the quality of the solution, is presented. The provided method could be the optimization tool used by the Independent System Operator of a centralized Power Pool. The solution procedure diminishes the conflict of interest in determining energy prices. A realistic large-scale case study illustrates the behavior of the presented approach. (Author)

  10. New design of an RSFQ parallel multiply-accumulate unit

    International Nuclear Information System (INIS)

    Kataeva, Irina; Engseth, Henrik; Kidiyarova-Shevchenko, Anna

    2006-01-01

    The multiply-accumulate unit (MAC) is a central component of a successive interference canceller, an advanced receiver for W-CDMA base stations. A 4 x 4 two's complement fixed point RSFQ MAC with rounding to 5 bits has been simulated using VHDL, and maximum performance is equal to 24 GMACS (giga-multiply-accumulates per second). The clock distribution network has been re-designed from a linear ripple to a binary tree network in order to eliminate the data dependence of the clock propagation speed and reduce the number of Josephson junctions in clock lines. The 4 x 4 bit MAC has been designed for the HYPRES 4.5 kA cm -2 process and its components have been experimentally tested at low frequency: the 5-bit combiner, using an exhaustive test pattern, had margins on DC bias voltage of ± 18%, and the 4 x 4 parallel multiplier had margins equal to ± 2%

  11. Multiplier Accounting of Indian Mining Industry: The Application

    Science.gov (United States)

    Hussain, Azhar; Karmakar, Netai Chandra

    2017-10-01

    In the previous paper (Hussain and Karmakar in Inst Eng India Ser, 2014. doi: 10.1007/s40033-014-0058-0), the concepts of input-output transaction matrix and multiplier were explained in detail. Input-output multipliers are indicators used for predicting the total impact on an economy due to changes in its industrial demand and output which is calculated using transaction matrix. The aim of this paper is to present an application of the concepts with respect to the mining industry, showing progress in different sectors of mining with time and explaining different outcomes from the results obtained. The analysis shows that a few mineral industries saw a significant growth in their multiplier values over the years.

  12. Dark energy from modified gravity with Lagrange multipliers

    International Nuclear Information System (INIS)

    Capozziello, Salvatore; Matsumoto, Jiro; Nojiri, Shin'ichi; Odintsov, Sergei D.

    2010-01-01

    We study scalar-tensor theory, k-essence and modified gravity with Lagrange multiplier constraint which role is to reduce the number of degrees of freedom. Dark Energy cosmology of different types (ΛCDM, unified inflation with DE, smooth non-phantom/phantom transition epoch) is reconstructed in such models. It is demonstrated that presence of Lagrange multiplier simplifies the reconstruction scenario. It is shown that mathematical equivalence between scalar theory and F(R) gravity is broken due to presence of constraint. The cosmological evolution is defined by the second F 2 (R) function dictated by the constraint. The convenient F(R) gravity sector is relevant for local tests. This opens the possibility to make originally non-realistic theory to be viable by adding the corresponding constraint. A general discussion on the role of Lagrange multipliers to make higher-derivative gravity canonical is developed.

  13. Study on neutron irradiation behavior of beryllium as neutron multiplier

    Energy Technology Data Exchange (ETDEWEB)

    Ishitsuka, Etsuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment

    1998-03-01

    More than 300 tons beryllium is expected to be used as a neutron multiplier in ITER, and study on the neutron irradiation behavior of beryllium as the neutron multiplier with Japan Materials Testing Reactor (JMTR) were performed to get the engineering data for fusion blanket design. This study started as the study on the tritium behavior in beryllium neutron reflector in order to make clear the generation mechanism on tritium of JMTR primary coolant since 1985. These experiences were handed over to beryllium studies for fusion study, and overall studies such as production technology of beryllium pebbles, irradiation behavior evaluation and reprocessing technology have been started since 1990. In this presentation, study on the neutron irradiation behavior of beryllium as the neutron multiplier with JMTR was reviewed from the point of tritium release, thermal properties, mechanical properties and reprocessing technology. (author)

  14. Splay states in globally coupled Josephson arrays: Analytical prediction of Floquet multipliers

    International Nuclear Information System (INIS)

    Strogatz, S.H.; Mirollo, R.E.

    1993-01-01

    In recent numerical experiments on series arrays of overdamped Josephson junctions, Nichols and Wiesenfeld [Phys. Rev. A 45, 8430 (1992)] discovered that the periodic states known as splay states are neutrally stable in all but four directions in phase space. We present a theory that accounts for this enormous degree of neutral stability. The theory also predicts the four non-neutral Floquet multipliers to within 0.1% of their numerically computed values. The analytical approach used here may be appli- cable to other globally coupled systems of oscillators, such as multimode lasers, electronic oscillator circuits, and solid-state laser arrays

  15. Analysis of current situation of information disclosure of listed companies on GEM

    Directory of Open Access Journals (Sweden)

    Zhirong Shen

    2017-03-01

    Full Text Available In the afternoon on October 23th, 2009, GEM was officially launched in our country. Due to the lack of experience in the market supervision, information disclosure violations frequently occurred. In April 2015, Shenzhen Stock Exchange puts forward morning information disclosure system to strengthen the reform of information disclosure system. Therefore, this paper deeply focuses on the current situation of information disclosure violations on GEM for the purpose of attracting more attention to the problems. Through studying the information disclosure violations of the listed companies on GEM from 2011 to September 30th, 2015, this paper divides the violations into the following four types: false record, misleading statement, material misstatement and delayed disclosure. On the other hand, we find that these types of violations are concurrent. From this discussion, we may safely draw the conclusion that the information disclosure of listed companies on GEM has the problem of untruthfulness, incorrectness, incompleteness and delay.

  16. First results with the general equilibrium model GEM-E3 Switzerland

    International Nuclear Information System (INIS)

    Bahn, O.; Frei, C.

    2000-01-01

    The GEM-E3 model has been implemented and applied for Switzerland. It has been in particular used to assess an ecological tax reform in Switzerland. Results of this analysis are presented here. (author)

  17. Time efficient signed Vedic multiplier using redundant binary representation

    Directory of Open Access Journals (Sweden)

    Ranjan Kumar Barik

    2017-03-01

    Full Text Available This study presents a high-speed signed Vedic multiplier (SVM architecture using redundant binary (RB representation in Urdhva Tiryagbhyam (UT sutra. This is the first ever effort towards extension of Vedic algorithms to the signed numbers. The proposed multiplier architecture solves the carry propagation issue in UT sutra, as carry free addition is possible in RB representation. The proposed design is coded in VHDL and synthesised in Xilinx ISE 14.4 of various FPGA devices. The proposed SVM architecture has better speed performances as compared with various state-of-the-art conventional as well as Vedic architectures.

  18. Radial multipliers on amalgamated free products of II-factors

    DEFF Research Database (Denmark)

    Möller, Sören

    2014-01-01

    Let ℳi be a family of II1-factors, containing a common II1-subfactor 풩, such that [ℳi : 풩] ∈ ℕ0 for all i. Furthermore, let ϕ: ℕ0 → ℂ. We show that if a Hankel matrix related to ϕ is trace-class, then there exists a unique completely bounded map Mϕ on the amalgamated free product of the ℳi...... with amalgamation over 풩, which acts as a radial multiplier. Hereby, we extend a result of Haagerup and the author for radial multipliers on reduced free products of unital C*- and von Neumann algebras....

  19. New stable multiply charged negative atomic ions in linearly polarized superintense laser fields

    International Nuclear Information System (INIS)

    Wei Qi; Kais, Sabre; Moiseyev, Nimrod

    2006-01-01

    Singly charged negative atomic ions exist in the gas phase and are of fundamental importance in atomic and molecular physics. However, theoretical calculations and experimental results clearly exclude the existence of any stable doubly-negatively-charged atomic ion in the gas phase, only one electron can be added to a free atom in the gas phase. In this report, using the high-frequency Floquet theory, we predict that in a linear superintense laser field one can stabilize multiply charged negative atomic ions in the gas phase. We present self-consistent field calculations for the linear superintense laser fields needed to bind extra one and two electrons to form He - , He 2- , and Li 2- , with detachment energies dependent on the laser intensity and maximal values of 1.2, 0.12, and 0.13 eV, respectively. The fields and frequencies needed for binding extra electrons are within experimental reach. This method of stabilization is general and can be used to predict stability of larger multiply charged negative atomic ions

  20. Financial recognition of material misstatement risks of listed companies on GEM

    OpenAIRE

    Jie Ming; Yicong Jiang

    2017-01-01

    Listed companies on GEM are characterized by strong innovation, great growth ability, high risks and high yields. Starting from these characteristics, this paper carries out analysis by using the financial indicators that are effective to recognize the material misstatement risks and easy to be acquired, and combines with the sample data with high material misstatement risks on GEM in 2012 to 2014 to test the significance of spss difference, and finds that the material misstatement company an...

  1. Systematic measurements of the gain and the energy resolution of single and double mask GEM detectors

    International Nuclear Information System (INIS)

    Biswas, S.; Schmidt, D.J.; Abuhoza, A.; Frankenfeld, U.; Garabatos, C.; Hehner, J.; Kleipa, V.; Morhardt, T.; Schmidt, C.J.; Schmidt, H.R.; Wiechula, J.

    2016-01-01

    Systematic studies on the gain and the energy resolution have been carried out by varying the voltage across the GEM foils for both single mask and double mask triple GEM detector prototypes. Variation of the gain and the energy resolution has also been measured by varying either the drift voltage, transfer voltage and induction voltage keeping other voltages constant. The results of the systematic measurements have been presented.

  2. Data Integration for Spatio-Temporal Patterns of Gene Expression of Zebrafish development: the GEMS database

    Directory of Open Access Journals (Sweden)

    Belmamoune Mounia

    2008-06-01

    Full Text Available The Gene Expression Management System (GEMS is a database system for patterns of gene expression. These patterns result from systematic whole-mount fluorescent in situ hybridization studies on zebrafish embryos. GEMS is an integrative platform that addresses one of the important challenges of developmental biology: how to integrate genetic data that underpin morphological changes during embryogenesis. Our motivation to build this system was by the need to be able to organize and compare multiple patterns of gene expression at tissue level. Integration with other developmental and biomolecular databases will further support our understanding of development. The GEMS operates in concert with a database containing a digital atlas of zebrafish embryo; this digital atlas of zebrafish development has been conceived prior to the expansion of the GEMS. The atlas contains 3D volume models of canonical stages of zebrafish development in which in each volume model element is annotated with an anatomical term. These terms are extracted from a formal anatomical ontology, i.e. the Developmental Anatomy Ontology of Zebrafish (DAOZ. In the GEMS, anatomical terms from this ontology together with terms from the Gene Ontology (GO are also used to annotate patterns of gene expression and in this manner providing mechanisms for integration and retrieval . The annotations are the glue for integration of patterns of gene expression in GEMS as well as in other biomolecular databases. At the one hand, zebrafish anatomy terminology allows gene expression data within GEMS to be integrated with phenotypical data in the 3D atlas of zebrafish development. At the other hand, GO terms extend GEMS expression patterns integration to a wide range of bioinformatics resources.

  3. The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow.

    Science.gov (United States)

    Roper, Kimberley A; Berry, Malcolm B; Ley, Steven V

    2013-01-01

    The application of a monolithic form of triphenylphosphine to the Ramirez gem-dibromoolefination reaction using flow chemistry techniques is reported. A variety of gem-dibromides were synthesised in high purity and excellent yield following only removal of solvent and no further off-line purification. It is also possible to perform the Appel reaction using the same monolith and the relationship between the mechanisms of the two reactions is discussed.

  4. The application of a monolithic triphenylphosphine reagent for conducting Ramirez gem-dibromoolefination reactions in flow

    Directory of Open Access Journals (Sweden)

    Kimberley A. Roper

    2013-09-01

    Full Text Available The application of a monolithic form of triphenylphosphine to the Ramirez gem-dibromoolefination reaction using flow chemistry techniques is reported. A variety of gem-dibromides were synthesised in high purity and excellent yield following only removal of solvent and no further off-line purification. It is also possible to perform the Appel reaction using the same monolith and the relationship between the mechanisms of the two reactions is discussed.

  5. 16 CFR 23.25 - Misuse of the word “gem.”

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Misuse of the word âgem.â 23.25 Section 23... JEWELRY, PRECIOUS METALS, AND PEWTER INDUSTRIES § 23.25 Misuse of the word “gem.” (a) It is unfair or deceptive to use the word “gem” to describe, identify, or refer to a ruby, sapphire, emerald, topaz, or...

  6. Gains in the Education of Mathematics and Science GEMS: Teaching Robotics to High School Students

    Science.gov (United States)

    2013-01-01

    find amusing but that we find of less educational value, like having the robots say comical things. Those who have more teaching time would doubtless...Gains in the Education of Mathematics and Science GEMS: Teaching Robotics to High School Students by Edward M. Measure and Edward Creegan...TR-6220 January 2013 Gains in the Education of Mathematics and Science (GEMS): Teaching Robotics to High School Students Edward M

  7. Characterization of the allergen Sol gem 2 from the fire ant venom, Solenopsis geminata

    Directory of Open Access Journals (Sweden)

    S Sukprasert

    2012-01-01

    Full Text Available Sol i 2 is a potent allergen in Solenopsis invicta venom, and most humans exhibit reactivity to it. The Sol gem 2 allergen found in the venom of the Thai tropical fire ant Solenopsis geminata was analysed in the present study. The protein was present in higher amounts than other proteins, as determined by SDS-PAGE, and presumably has allergenic properties similar to those of Sol i 2. Sol gem 2 molecular weight is 28 and 15 kDa, respectively, under non-reducing and reducing conditions, indicating that its native form is a dimer. LC-MS/MS analysis confirmed its similarity to Sol i 2. The mono/dimeric form of Sol gem 2 was determined to be relevant by proteomic approach and immunoblotting. An anti-Sol gem 2 antibody was produced in mice, with a titer greater than 1:800 according to the Western blotting analysis. The Sol gem 2-neutralising activity of this antibody was determined in crickets. The paralytic dose 50 (PD50 of crude S. geminata venom was elevated from 0.18 mg/g of body weight to more than 0.90 mg/g of body weight after preincubation with antibody at a ratio of 1:1. These results suggest that Sol gem 2 plays an important role in mediating the effects of the piperidine derivatives in the venom.

  8. Performance of a large-area GEM detector read out with wide radial zigzag strips

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Aiwu, E-mail: azhang@fit.edu; Bhopatkar, Vallary; Hansen, Eric; Hohlmann, Marcus; Khanal, Shreeya; Phipps, Michael; Starling, Elizabeth; Twigger, Jessie; Walton, Kimberly

    2016-03-01

    A 1-meter-long trapezoidal Triple-GEM detector with wide readout strips was tested in hadron beams at the Fermilab Test Beam Facility in October 2013. The readout strips have a special zigzag geometry and run radially with an azimuthal pitch of 1.37 mrad to measure the azimuthal ϕ-coordinate of incident particles. The zigzag geometry of the readout reduces the required number of electronic channels by a factor of three compared to conventional straight readout strips while preserving good angular resolution. The average crosstalk between zigzag strips is measured to be an acceptable 5.5%. The detection efficiency of the detector is (98.4±0.2)%. When the non-linearity of the zigzag-strip response is corrected with track information, the angular resolution is measured to be (193±3) μrad, which corresponds to 14% of the angular strip pitch. Multiple Coulomb scattering effects are fully taken into account in the data analysis with the help of a stand-alone Geant4 simulation that estimates interpolated track errors.

  9. Evaluation of ozone profile and tropospheric ozone retrievals from GEMS and OMI spectra

    Directory of Open Access Journals (Sweden)

    J. Bak

    2013-02-01

    Full Text Available South Korea is planning to launch the GEMS (Geostationary Environment Monitoring Spectrometer instrument into the GeoKOMPSAT (Geostationary Korea Multi-Purpose SATellite platform in 2018 to monitor tropospheric air pollutants on an hourly basis over East Asia. GEMS will measure backscattered UV radiances covering the 300–500 nm wavelength range with a spectral resolution of 0.6 nm. The main objective of this study is to evaluate ozone profiles and stratospheric column ozone amounts retrieved from simulated GEMS measurements. Ozone Monitoring Instrument (OMI Level 1B radiances, which have the spectral range 270–500 nm at spectral resolution of 0.42–0.63 nm, are used to simulate the GEMS radiances. An optimal estimation-based ozone profile algorithm is used to retrieve ozone profiles from simulated GEMS radiances. Firstly, we compare the retrieval characteristics (including averaging kernels, degrees of freedom for signal, and retrieval error derived from the 270–330 nm (OMI and 300–330 nm (GEMS wavelength ranges. This comparison shows that the effect of not using measurements below 300 nm on retrieval characteristics in the troposphere is insignificant. However, the stratospheric ozone information in terms of DFS decreases greatly from OMI to GEMS, by a factor of ∼2. The number of the independent pieces of information available from GEMS measurements is estimated to 3 on average in the stratosphere, with associated retrieval errors of ~1% in stratospheric column ozone. The difference between OMI and GEMS retrieval characteristics is apparent for retrieving ozone layers above ~20 km, with a reduction in the sensitivity and an increase in the retrieval errors for GEMS. We further investigate whether GEMS can resolve the stratospheric ozone variation observed from high vertical resolution Earth Observing System (EOS Microwave Limb Sounder (MLS. The differences in stratospheric ozone profiles between GEMS and MLS are comparable to those

  10. ANALYSIS OF THE INVESTMENT ARBITRAGE STRATEGY USING FINANCIAL MULTIPLIERS

    Directory of Open Access Journals (Sweden)

    Dmitry S. Pashkov

    2013-01-01

    Full Text Available This article describes an algorithm for stock pairs trading using financial multipliers of underlying companies. This algorithm has been tested on historical data and compared with classical Bollinger bands strategy. The results of tests were presented for two financial sectors of US stock market.

  11. Garbage-free reversible constant multipliers for arbitrary integers

    DEFF Research Database (Denmark)

    Mogensen, Torben Ægidius

    2013-01-01

    We present a method for constructing reversible circuitry for multiplying integers by arbitrary integer constants. The method is based on Mealy machines and gives circuits whose size are (in the worst case) linear in the size of the constant. This makes the method unsuitable for large constants...

  12. Smooth bifurcation for variational inequalities based on Lagrange multipliers

    Czech Academy of Sciences Publication Activity Database

    Eisner, Jan; Kučera, Milan; Recke, L.

    2006-01-01

    Roč. 19, č. 9 (2006), s. 981-1000 ISSN 0893-4983 R&D Projects: GA AV ČR(CZ) IAA100190506 Institutional research plan: CEZ:AV0Z10190503 Keywords : abstract variational inequality * bifurcation * Lagrange multipliers Subject RIV: BA - General Mathematics

  13. Detection of differential item functioning using Lagrange multiplier tests

    NARCIS (Netherlands)

    Glas, Cornelis A.W.

    1998-01-01

    Abstract: In the present paper it is shown that differential item functioning can be evaluated using the Lagrange multiplier test or Rao’s efficient score test. The test is presented in the framework of a number of IRT models such as the Rasch model, the OPLM, the 2-parameter logistic model, the

  14. Detection of differential item functioning using Lagrange multiplier tests

    NARCIS (Netherlands)

    Glas, Cornelis A.W.

    1996-01-01

    In this paper it is shown that differential item functioning can be evaluated using the Lagrange multiplier test or C. R. Rao's efficient score test. The test is presented in the framework of a number of item response theory (IRT) models such as the Rasch model, the one-parameter logistic model, the

  15. Lagrange-multiplier tests for weak exogeneity: a synthesis.

    NARCIS (Netherlands)

    Boswijk, H.P.; Urbain, J.P.

    1997-01-01

    This paper unifies two seemingly separate approaches to test weak exogeneity in dynamic regression models with Lagrange-multiplier statistics. The first class of tests focuses on the orthogonality between innovations and conditioning variables, and thus is related to the Durbin-Wu-Hausman

  16. Fiscal multipliers over the growth cycle : evidence from Malaysia

    OpenAIRE

    Rafiq, Sohrab; Zeufack, Albert

    2012-01-01

    This paper explores the stabilisation properties of fiscal policy in Malaysia using a model incorporating nonlinearities into the dynamic relationship between fiscal policy and real economic activity over the growth cycle. The paper also investigates how output multipliers for government purchases may alter for different components of government spending. The authors find that fiscal polic...

  17. A database analysis of information on multiply charged ions

    International Nuclear Information System (INIS)

    Delcroix, J.L.

    1989-01-01

    A statistical analysis of data related to multiply charged ions, is performed in GAPHYOR data base: over-all statistics by ionization degree from q=1 to q=99, 'historical' development from 1975 to 1987, distribution (for q≥ 5) over physical processes (energy levels, charge exchange,...) and chemical elements

  18. Multiple images of our galaxy in closed, multiply connected cosmologies

    International Nuclear Information System (INIS)

    Fagundes, H.V.

    1985-01-01

    Friedmanian cosmology with multiply connected spatial sections allows multiple images of cosmic sources, in particular of the galaxy itself. This is illustrated with a specific example of a closed hyperbolic model and a brief mention of a spherical model. Such images may eventually become observable (or recognized as such), thus providing a new test of relativistic cosmology. (Author) [pt

  19. A CMOS four-quadrant analog current multiplier

    NARCIS (Netherlands)

    Wiegerink, Remco J.

    1991-01-01

    A CMOS four-quadrant analog current multiplier is described. The circuit is based on the square-law characteristic of an MOS transistor and is insensitive to temperature and process variations. The circuit is insensitive to the body effect so it is not necessary to place transistors in individual

  20. The evolution of unconditional strategies via the 'multiplier effect'.

    Science.gov (United States)

    McNamara, John M; Dall, Sasha R X

    2011-03-01

    Ostensibly, it makes sense in a changeable world to condition behaviour and development on information when it is available. Nevertheless, unconditional behavioural and life history strategies are widespread. Here, we show how intergenerational effects can limit the evolutionary value of responding to reliable environmental cues, and thus favour the evolutionary persistence of otherwise paradoxical unconditional strategies. While cue-ignoring genotypes do poorly in the wrong environments, in the right environment they will leave many copies of themselves, which will themselves leave many copies, and so on, leading genotypes to accumulate in habitats in which they do well. We call this 'The Multiplier Effect'. We explore the consequences of the multiplier effect by focussing on the ecologically important phenomenon of natal philopatry. We model the environment as a large number of temporally varying breeding sites connected by natal dispersal between sites. Our aim is to identify which aspects of an environment promote the multiplier effect. We show, if sites remain connected through some background level of 'accidental' dispersal, unconditional natal philopatry can evolve even when there is density dependence (with its accompanying kin competition effects), and cues that are only mildly erroneous. Thus, the multiplier effect may underpin the evolution and maintenance of unconditional strategies such as natal philopatry in many biological systems. © 2011 Blackwell Publishing Ltd/CNRS.

  1. A cascaded three-phase symmetrical multistage voltage multiplier

    International Nuclear Information System (INIS)

    Iqbal, Shahid; Singh, G K; Besar, R; Muhammad, G

    2006-01-01

    A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM

  2. Robust formation control of marine surface craft using Lagrange multipliers

    DEFF Research Database (Denmark)

    Ihle, Ivar-Andre F.; Jouffroy, Jerome; Fossen, Thor I.

    2006-01-01

    This paper presents a formation modelling scheme based on a set of inter-body constraint functions and Lagrangian multipliers. Formation control for a °eet of marine craft is achieved by stabilizing the auxiliary constraints such that the desired formation con¯guration appears. In the proposed fr...

  3. Familiar Sports and Activities Adapted for Multiply Impaired Persons.

    Science.gov (United States)

    Schilling, Mary Lou, Ed.

    1984-01-01

    Means of adapting some familiar and popular physical activities for multiply impaired persons are described. Games reviewed are dice baseball, one base baseball, in-house bowling, wheelchair bowling, ramp bowling, swing-ball bowling, table tennis, shuffleboard, beanbag bingo and tic-tac-toe, balloon basketball, circle football, and wheelchair…

  4. Gaseous elemental mercury (GEM fluxes over canopy of two typical subtropical forests in south China

    Directory of Open Access Journals (Sweden)

    Q. Yu

    2018-01-01

    Full Text Available Mercury (Hg exchange between forests and the atmosphere plays an important role in global Hg cycling. The present estimate of global emission of Hg from natural source has large uncertainty, partly due to the lack of chronical and valid field data, particularly for terrestrial surfaces in China, the most important contributor to global atmospheric Hg. In this study, the micrometeorological method (MM was used to continuously observe gaseous elemental mercury (GEM fluxes over forest canopy at a mildly polluted site (Qianyanzhou, QYZ and a moderately polluted site (Huitong, HT, near a large Hg mine in subtropical south China for a full year from January to December in 2014. The GEM flux measurements over forest canopy in QYZ and HT showed net emission with annual average values of 6.67 and 0.30 ng m−2 h−1, respectively. Daily variations of GEM fluxes showed an increasing emission with the increasing air temperature and solar radiation in the daytime to a peak at 13:00, and decreasing emission thereafter, even as a GEM sink or balance at night. High temperature and low air Hg concentration resulted in the high Hg emission in summer. Low temperature in winter and Hg absorption by plant in spring resulted in low Hg emission, or even adsorption in the two seasons. GEM fluxes were positively correlated with air temperature, soil temperature, wind speed, and solar radiation, while it is negatively correlated with air humidity and atmospheric GEM concentration. The lower emission fluxes of GEM at the moderately polluted site (HT when compared with that in the mildly polluted site (QYZ may result from a much higher adsorption fluxes at night in spite of a similar or higher emission fluxes during daytime. This shows that the higher atmospheric GEM concentration at HT restricted the forest GEM emission. Great attention should be paid to forests as a crucial increasing Hg emission source with the decreasing atmospheric GEM concentration

  5. Design studies for an advanced ECR ion source for multiply charged ion beam generation

    International Nuclear Information System (INIS)

    Alton, G.D.

    1994-01-01

    An innovative technique: for increasing ion source intensity is described which, in principle, could lead to significant advances in ECR ion source technology for multiply charged ion beam formation. The advanced concept design uses a minimum-B magnetic mirror geometry which consists of a multi-cusp, magnetic field, to assist in confining the plasma radially, a flat central field for tuning to the ECR resonant condition, and specially tailored min-or fields in the end zones to confine the plasma in the axial direction. The magnetic field is designed to achieve an axially symmetric plasma ''volume'' with constant mod-B, which extends over the length of the central field region. This design, which strongly contrasts w h the ECR ''surfaces'' characteristic of conventional ECR ion sources, results in dramatic increases in the absorption of RF power, thereby increasing the electron temperature and ''hot'' electron population within the ionization volume of the source

  6. Characterization of photo-multiplier tube as ex-vessel radiation detector in tokamak

    Science.gov (United States)

    Jo, Jungmin; Cheon, MunSeong; Kim, Junghee; An, YoungHwa; Park, Seungil; Chung, Kyoung-Jae; Hwang, Y. S.

    2017-09-01

    Feasibility of using conventional photo-multiplier tubes (PMTs) without a scintillator as an ex-vessel radiation detector in a tokamak environment is studied. Basic irradiation tests using standard gamma ray sources and a d-d neutron generator showed that the PMT is responding both to gamma photons and neutrons, possibly due to the direct generation of secondary electrons inside the PMT by the impingement of high energy photons. Because of the selective sensitivity of the PMT to hard x-ray and neutrons in ohmic and neutral beam injected plasmas, respectively, it is shown that the PMT with certain configuration can be utilized either to monitor the fluctuation in the fusion neutron generation rate or to study the behavior of runaway electrons in tokamaks.

  7. Californium Multiplier. Part I. Design for neutron radiography

    International Nuclear Information System (INIS)

    Crosbie, K.L.; Preskitt, C.A.; John, J.; Hastings, J.D.

    1982-01-01

    The Californium Multiplier (CFX) is a subcritical assembly of enriched uranium surrounding a californium-252 neutron source. The function of the CFX is to multiply the neutrons emitted by the source to a number sufficient for neutron radiography. The CFX is designed to provide a collimated beam of thermal neutrons from which the gamma radiation is filtered, and the scattered neutrons are reduced to make it suitable for high resolution radiography. The entire system has inherent safety features, which provide for system and personnel safety, and it operates at moderate cost. In Part I, the CFX and the theory of its operation are described in detail. Part II covers the performance of the Mound Facility CFX

  8. Generation of fast multiply charged ions in conical targets

    International Nuclear Information System (INIS)

    Demchenko, V.V.; Chukbar, K.V.

    1990-01-01

    So-called conical targets, when the thermonuclear fuel is compressed and heated in a conical cavity in a heavy material (lead, gold, etc.) with the help of a spherical segment that is accelerated by a laser pulse or a beam of charged particles, are often employed in experimental studies of inertial-confinement fusion. In spite of the obvious advantages of such a scheme, one of which is a significant reduction of the required energy input compared with the complete spherical target, it also introduces additional effects into the process of cumulation of energy. In this paper the authors call attention to an effect observed in numerical calculations: the hydrodynamic heating of a small group of multiply charged heavy ions of the walls of the conical cavity up to high energies (T i approx-gt 100 keV). This effect ultimately occurs as a result of the high radiation losses of a multiply charged plasma

  9. Gravity model improvement using GEOS 3 /GEM 9 and 10/. [and Seasat altimetry data

    Science.gov (United States)

    Lerch, F. J.; Wagner, C. A.; Klosko, S. M.; Laubscher, R. E.

    1979-01-01

    Although errors in previous gravity models have produced large uncertainties in the orbital position of GEOS 3, significant improvement has been obtained with new geopotential solutions, Goddard Earth Model (GEM) 9 and 10. The GEM 9 and 10 solutions for the potential coefficients and station coordinates are presented along with a discussion of the new techniques employed. Also presented and discussed are solutions for three fundamental geodetic reference parameters, viz. the mean radius of the earth, the gravitational constant, and mean equatorial gravity. Evaluation of the gravity field is examined together with evaluation of GEM 9 and 10 for orbit determination accuracy. The major objectives of GEM 9 and 10 are achieved. GEOS 3 orbital accuracies from these models are about 1 m in their radial components for 5-day arc lengths. Both models yield significantly improved results over GEM solutions when compared to surface gravimetry, Skylab and GEOS 3 altimetry, and highly accurate BE-C (Beacon Explorer-C) laser ranges. The new values of the parameters discussed are given.

  10. The role of evaporites in the formation of gems during metamorphism of carbonate platforms: a review

    Science.gov (United States)

    Giuliani, Gaston; Dubessy, Jean; Ohnenstetter, Daniel; Banks, David; Branquet, Yannick; Feneyrol, Julien; Fallick, Anthony E.; Martelat, Jean-Emmanuel

    2018-01-01

    The mineral and fluid inclusions trapped by gemstones during the metamorphism of carbonate platform successions are precious markers for the understanding of gem genesis. The nature and chemical composition of inclusions highlight the major contribution of evaporites through dissolution or fusion, depending on the temperature of formation from greenschist to granulite facies. The fluids are highly saline NaCl-brines circulating either in an open system in the greenschist facies (Colombian and Afghan emeralds) and with huge fluid-rock metasomatic interactions, or sulphurous fluids (ruby, garnet tsavorite, zoisite tanzanite and lapis-lazuli) or molten salts formed in a closed system with a low fluid mobility (ruby in marble) in the conditions of the amphibolite to granulite facies. These chloride-fluoride-sulphate ± carbonate-rich fluids scavenged the metals essential for gem formation. At high temperature, the anions SO4 2-, NO3 -, BO3 - and F- are powerful fluxes which lower the temperature of chloride- and fluoride-rich ionic liquids. They provided transport over a very short distance of aluminium and/or silica and transition metals which are necessary for gem growth. In summary, the genetic models proposed for these high-value and ornamental gems underline the importance of the metamorphism of evaporites formed on continental carbonate shelves and emphasise the chemical power accompanying metamorphism at moderate to high temperatures of evaporite-rich and organic matter-rich protoliths to form gem minerals.

  11. Gaseous elemental mercury (GEM emissions from snow surfaces in northern New York.

    Directory of Open Access Journals (Sweden)

    J Alexander Maxwell

    Full Text Available Snow surface-to-air exchange of gaseous elemental mercury (GEM was measured using a modified Teflon fluorinated ethylene propylene (FEP dynamic flux chamber (DFC in a remote, open site in Potsdam, New York. Sampling was conducted during the winter months of 2011. The inlet and outlet of the DFC were coupled with a Tekran Model 2537A mercury (Hg vapor analyzer using a Tekran Model 1110 two port synchronized sampler. The surface GEM flux ranged from -4.47 ng m(-2 hr(-1 to 9.89 ng m(-2 hr(-1. For most sample periods, daytime GEM flux was strongly correlated with solar radiation. The average nighttime GEM flux was slightly negative and was not well correlated with any of the measured meteorological variables. Preliminary, empirical models were developed to estimate GEM emissions from snow surfaces in northern New York. These models suggest that most, if not all, of the Hg deposited with and to snow is reemitted to the atmosphere.

  12. Gaseous elemental mercury (GEM) emissions from snow surfaces in northern New York.

    Science.gov (United States)

    Maxwell, J Alexander; Holsen, Thomas M; Mondal, Sumona

    2013-01-01

    Snow surface-to-air exchange of gaseous elemental mercury (GEM) was measured using a modified Teflon fluorinated ethylene propylene (FEP) dynamic flux chamber (DFC) in a remote, open site in Potsdam, New York. Sampling was conducted during the winter months of 2011. The inlet and outlet of the DFC were coupled with a Tekran Model 2537A mercury (Hg) vapor analyzer using a Tekran Model 1110 two port synchronized sampler. The surface GEM flux ranged from -4.47 ng m(-2) hr(-1) to 9.89 ng m(-2) hr(-1). For most sample periods, daytime GEM flux was strongly correlated with solar radiation. The average nighttime GEM flux was slightly negative and was not well correlated with any of the measured meteorological variables. Preliminary, empirical models were developed to estimate GEM emissions from snow surfaces in northern New York. These models suggest that most, if not all, of the Hg deposited with and to snow is reemitted to the atmosphere.

  13. The HadGEM2 family of Met Office Unified Model climate configurations

    Directory of Open Access Journals (Sweden)

    The HadGEM2 Development Team: G. M. Martin

    2011-09-01

    Full Text Available We describe the HadGEM2 family of climate configurations of the Met Office Unified Model, MetUM. The concept of a model "family" comprises a range of specific model configurations incorporating different levels of complexity but with a common physical framework. The HadGEM2 family of configurations includes atmosphere and ocean components, with and without a vertical extension to include a well-resolved stratosphere, and an Earth-System (ES component which includes dynamic vegetation, ocean biology and atmospheric chemistry. The HadGEM2 physical model includes improvements designed to address specific systematic errors encountered in the previous climate configuration, HadGEM1, namely Northern Hemisphere continental temperature biases and tropical sea surface temperature biases and poor variability. Targeting these biases was crucial in order that the ES configuration could represent important biogeochemical climate feedbacks. Detailed descriptions and evaluations of particular HadGEM2 family members are included in a number of other publications, and the discussion here is limited to a summary of the overall performance using a set of model metrics which compare the way in which the various configurations simulate present-day climate and its variability.

  14. Applications of Mapping and Tomographic Techniques in Gem Sciences

    Science.gov (United States)

    Shen, A. H.

    2014-12-01

    Gem Sciences are scientific studies of gemstones - their genesis, provenance, synthesis, enhancement, treatment and identification. As high quality forms of specific minerals, the gemstones exhibit unusual physical properties that are usually unseen in the regular counterparts. Most gemstones are colored by trace elements incorporated in the crystal lattice during various growth stages; forming coloration zones of various scales. Studying the spectral and chemical contrast across color zones helps elucidating the origins of colors. These are done by UV-visible spectrometers with microscope and LA-ICPMS in modern gemological laboratories. In the case of diamonds, their colored zones arise from various structural defects incorporated in different growth zones and are studied with FTIR spectrometers with IR microscope and laser photoluminescence spectrometers. Advancement in modern synthetic techniques such as chemical vapor deposition (CVD) has created some problem for identification. Some exploratory experiments in carbon isotope mapping were done on diamonds using SIMS. The most important issue in pearls is to identify one particular pearl being a cultured one or a natural pearl. The price difference can be enormous. Classical way of such identification is done by x-ray radiographs, which clearly show the bead and the nacre. Modern cultured pearl advancement has eliminated the need for an artificial bead, but a small piece of tissue instead. Nowadays, computer x-ray tomography (CT) scanning devices are used to depict the clear image of the interior of a pearl. In the Chinese jade market, filling fissures with epoxy and/or wax are very commonly seen. We are currently exploring Magnetic Resonance Imaging (MRI) technique to map the distribution of artificial resin within a polycrystalline aggregates.

  15. Inverse mass matrix via the method of localized lagrange multipliers

    Czech Academy of Sciences Publication Activity Database

    González, José A.; Kolman, Radek; Cho, S.S.; Felippa, C.A.; Park, K.C.

    2018-01-01

    Roč. 113, č. 2 (2018), s. 277-295 ISSN 0029-5981 R&D Projects: GA MŠk(CZ) EF15_003/0000493; GA ČR GA17-22615S Institutional support: RVO:61388998 Keywords : explicit time integration * inverse mass matrix * localized Lagrange multipliers * partitioned analysis Subject RIV: BI - Acoustics OBOR OECD: Applied mechanics Impact factor: 2.162, year: 2016 https://onlinelibrary.wiley.com/doi/10.1002/nme.5613

  16. On Lagrange Multipliers in Work with Quality and Reliability Assurance

    DEFF Research Database (Denmark)

    Vidal, Rene Victor Valqui; Becker, P.

    1986-01-01

    In optimizing some property of a system, reliability say, a designer usually has to accept certain constraints regarding cost, completion time, volume, weight, etc. The solution of optimization problems with boundary constraints can be helped substantially by the use of Lagrange multipliers...... in the areas of sales promotion and teaching. These maps illuminate the logic structure of solution sequences. One such map is shown, illustrating the application of LMT in one of the examples....

  17. Characterization of a prototype matrix of Silicon PhotoMultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Dinu, N. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France)], E-mail: dinu@lal.in2p3.fr; Barrillon, P.; Bazin, C. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Belcari, N.; Bisogni, M.G. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); Bondil-Blin, S. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Boscardin, M. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy); Chaumat, V. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Collazuol, G. [Scuola Normale Superiore (SNS), 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); De La Taille, C. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Del Guerra, A. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); Llosa, G. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); Marcatili, S. [Universita di Pisa, Dipartimento di Fisica ' E. Fermi' , 56127 Pisa (Italy); INFN, Sezione di Pisa, 56127 Pisa (Italy); Melchiorri, M.; Piemonte, C. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy); Puill, V. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Tarolli, A. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy); Vagnucci, J.F. [Laboratory of Linear Accelerator (LAL), IN2P3-CNRS, 91898 Orsay (France); Zorzi, N. [Fondazione Bruno Kessler (FBK-irst), 38050 Trento (Italy)

    2009-10-21

    This work reports on the electrical as well as the optical characterizations of a prototype matrix of Silicon PhotoMultipliers (SiPM). The electrical test consists of the measurement of the static (breakdown voltage, quenching resistance, post-breakdown dark current) as well as the dynamic characteristics (gain, dark count rate). The optical test consists of the estimation of the photon detection efficiency as a function of wavelength as well as operation voltage.

  18. Characterization of a prototype matrix of Silicon PhotoMultipliers

    International Nuclear Information System (INIS)

    Dinu, N.; Barrillon, P.; Bazin, C.; Belcari, N.; Bisogni, M.G.; Bondil-Blin, S.; Boscardin, M.; Chaumat, V.; Collazuol, G.; De La Taille, C.; Del Guerra, A.; Llosa, G.; Marcatili, S.; Melchiorri, M.; Piemonte, C.; Puill, V.; Tarolli, A.; Vagnucci, J.F.; Zorzi, N.

    2009-01-01

    This work reports on the electrical as well as the optical characterizations of a prototype matrix of Silicon PhotoMultipliers (SiPM). The electrical test consists of the measurement of the static (breakdown voltage, quenching resistance, post-breakdown dark current) as well as the dynamic characteristics (gain, dark count rate). The optical test consists of the estimation of the photon detection efficiency as a function of wavelength as well as operation voltage.

  19. Radial multipliers on reduced free products of operator algebras

    DEFF Research Database (Denmark)

    Haagerup, Uffe; Møller, Søren

    2012-01-01

    Let AiAi be a family of unital C¿C¿-algebras, respectively, of von Neumann algebras and ¿:N0¿C¿:N0¿C. We show that if a Hankel matrix related to ¿ is trace-class, then there exists a unique completely bounded map M¿M¿ on the reduced free product of the AiAi, which acts as a radial multiplier...

  20. Study of the electric field inside microchannel plate multipliers

    International Nuclear Information System (INIS)

    Gatti, E.; Oba, K.; Rehak, P.

    1982-01-01

    Electric field inside high gain microchannel plate multipliers was studied. The calculations were based directly on the solution of the Maxwell equations applied to the microchannel plate (MCP) rather than on the conventional lumped RC model. The results are important to explain the performance of MCP's, (1) under a pulsed bias tension and, (2) at high rate conditions. The results were tested experimentally and a new method of MCP operation free from the positive ion feedback was demonstrated