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1.
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2.
  • Ashrafi, S, et al. (författare)
  • Monte-Carlo simulation of the charged particle detector used in the NORDBALL gamma-ray spectrometer
  • 2001
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier. - 0167-5087. ; 458:3, s. 690-697
  • Tidskriftsartikel (refereegranskat)abstract
    • The NORDBALL silicon detector array for detecting light charged particles emitted in fusion evaporation reactions was simulated with the Monte-Carlo method. The data from the reaction of 261 MeV Ni-58 ions with Cr-50 nuclei in a 4.8 mg/cm(2) thick target was used to adjust the simulation parameters. Relative population of residual nuclei in the reaction was determined, by comparing the intensities of gamma -rays. (C) 2001 Elsevier Science B.V. All rights reserved.
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3.
  • Back, T, et al. (författare)
  • An educational tool for demonstrating the TOF-PET technique
  • 2001
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier. - 0167-5087. ; 471:1-2, s. 200-204
  • Tidskriftsartikel (refereegranskat)abstract
    • A detector system for positron emission tomography with time-of-flight capability has been built to serve as an educational tool for undergraduate students. The set-up consists of 48 BaF2 scintillator crystals, each coupled to a fast photo-multiplier tube, mounted in a circular geometry. The analogue detector pulses are handled by fast constant fraction discriminators. A dedicated unit reduces the 48 channels to eight channels via delay-fine encoding, and the signals are then fed to an eight channel fast time-to-digital converter. A VME processor sorts the events and sends them to a workstation where the coincident events are extracted. The time resolution of the detectors together with fast VME based electronics allows for time-of-flight measurements to improve on the signal-to-noise ratio in the, reconstructed images. The system can be used for different types of exercises for the students, varying from the fundamentals of scintillator detectors to advanced image reconstruction. The set-up is described and some results are presented. (C) 2001 Elsevier Science B.V. All rights reserved.
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4.
  • Cederkäll, Joakim, et al. (författare)
  • Relative enhancement of weak two-neutron exit channels in heavy-ion induced fusion-evaporation reactions
  • 1997
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier. - 0167-5087. ; 385:1, s. 166-170
  • Tidskriftsartikel (refereegranskat)abstract
    • A method to enhance weak two-neutron exit channels in heavy-ion induced fusion-evaporation reactions is demonstrated with a data set from the NORDBALL detector array, True two-neutron events are enhanced in relation to spurious events from cross-talk by a factor of 30. In the process the peak-to-background ratio in the coincident gamma-ray spectra improves more than 3 times.
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5.
  • Karlsson, U. O., et al. (författare)
  • Surface science at MAX-LAB
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier. - 0168-9002 .- 1872-9576. ; 282:2-3, s. 553-558
  • Tidskriftsartikel (refereegranskat)abstract
    • The 550 MeV storage ring at MAX-LAB provides synchrotron radiation for a large community of users. An important part of the scientific program is photoelectron spectroscopy studies of semiconductor and metal surfaces and interfaces. Here is a brief review of some of the experimental efforts obtained in this area. Results are shown for the Ge(100)2×1:As, Si(111):Au, Mo(110):Yb and Mo(110):Sm systems.
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6.
  • Pausch, G, et al. (författare)
  • RoSiB - a 4 pi silicon ball for charged-particle detection in EUROBALL
  • 2000
  • Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier. - 0167-5087. ; 443:03-feb, s. 304-318
  • Tidskriftsartikel (refereegranskat)abstract
    • A 4 pi silicon bail for detection and identification of light charged particles in large multidetector gamma-arrays as EUROBALL is presented. The design is based on a N = 42 ball with 12 pentagons and 30 hexagons as used in the GASP array. The absorptive material for gamma-rays is minimized to the detector thickness of 300 or 500 mu m and a 0.63 mm ceramic backing. The geometrical coverage is designed for about 90% of 4 pi. A pulse shape discrimination method with totally depleted detectors working in the reverse mount allows identifying protons and alpha-particles above an energy threshold of about 2 MeV. The performances of the ball were rested at the tandem - booster accelerator combination of the MPI Heidelberg in two experiments using the high-recoil reaction of 228 MeV Ni-58 + Ti-46 and the low-recoil reaction of 95 MeV O-16 + Ni-58. The two-dimensional spectra of zero-crossing (ZC) versus energy confirmed an excellent discrimination of protons and alpha-particles in all the detectors at different angles. The energy spectra of protons and alpha-particles measured in the experiments are presented. too. The gamma-spectra measured in coincidence with various combinations of emitted particles showed a high selectivity of the ball. The reduced total efficiency for protons of 59% and 55% and alpha-particles of 44% and 32% measured in a nuclear spectroscopy application is analyzed in a Monte-Carlo simulation (GEANT). It is due to a combined influence of a thick target needed to stop the recoiling residual nuclei and thick absorbers needed to protect the Si-detectors from scattered beam. The results along with the GEANT extrapolation to optimum experimental conditions confirm that RoSiB is a highly efficient and selective device for identification of rare reaction channels with heavy ions. (C) 2000 Elsevier Science B.V. All rights reserved.
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7.
  • Abdalla, M. A., et al. (författare)
  • A CMOS APS for dental X-ray imaging using scintillating sensors
  • 2001
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 460:1, s. 197-203
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we present an integrating CMOS Active Pixel Sensor (APS) circuit to be used with scintillator type X-ray sensors for intra oral dental X-ray imaging systems. Different pixel architectures were constructed to explore their performance characteristics and to study the feasibility of the development of such systems using the CMOS technology. A prototype 64 x 80 pixel array has been implemented in a CMOS 0.8 mum double poly n-well process with a pixel pitch of 50 mum. A spectral sensitivity measurement for the different pixels topologies, as well as measured X-ray direct absorption in the different APSs are presented. A measurement of the output signal showed a good linearity over a wide dynamic range. This chip showed that the very low sensitivity of the CMOS APSs to direct X-ray exposure adds a great advantage to the various CMOS advantages over CCD-based imaging systems,
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8.
  • Abdalla, M. A., et al. (författare)
  • An integrating CMOS APS for X-ray imaging with an in-pixel preamplifier
  • 2001
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 466:1, s. 232-236
  • Tidskriftsartikel (refereegranskat)abstract
    • We present in this paper an integrating CMOS Active Pixel Sensor (APS) circuit coated with scintillator type sensors for intra-oral dental X-ray imaging systems. The photosensing element in the pixel is formed by the p-diffusion on the n-well diode. The advantage of this photosensor is its very low direct absorption of X-rays compared to the other available photosensing elements in the CMOS pixel. The pixel features an integrating capacitor in the feedback loop of a preamplifier of a finite gain in order to increase the optical sensitivity. To verify the effectiveness of this in-pixel preamplification, a prototype 32 x 80 element CMOS active pixel array was implemented in a 0.8 mum CMOS double poly, n-well process with a pixel pitch of 50 mum. Measured results confirmed the improved optical sensitivity performance of the APS. Various measurements on device performance are presented.
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9.
  • Adiels, Lars, et al. (författare)
  • A π0 and η spectrometer of lead glass and BGO for momenta up to 1 GeV/c
  • 1986
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 244:3, s. 380-390
  • Tidskriftsartikel (refereegranskat)abstract
    • A spectrometer consisting of two sets of bismuth germanium oxide (BGO) crystals and a lead-glass array has been used to measure the [pi]0 and [eta] momentum spectra produced from proton-antiproton annihilations at rest. We describe the test of the BGO sets in electron beams of energies from 50 to 450 MeV. We discuss the method of construction and calibration of the lead-glass array, as well as procedures to extract the energy and position resolutions for detected photons. A momentum resolution ([sigma]) for [pi]0’s and [eta]’s of 4% and 3%, respectively has been achieved at momenta below 1 GeV/c.
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10.
  • Adriani, O., et al. (författare)
  • The PAMELA experiment on satellite and its capability in cosmic rays measurements
  • 2002
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 478:02-jan, s. 114-118
  • Tidskriftsartikel (refereegranskat)abstract
    • The PAMELA equipment will be assembled in 2001 and installed on board the Russian satellite Resurs. PAMELA is conceived mainly to study the antiproton and positron fluxes in cosmic rays up to high energy (190 GeV for (p) over bar and 270 GeV for e(+)) and to search antinuclei, up to 30 GeV/n, with a sensitivity of 10(-7) in the He/He ratio. The PAMELA telescope consists of. a magnetic spectrometer made up of a permanent magnet system equipped with double sided microstrip silicon detectors a transition radiation detector made up of active layers of proportional straw tubes interleaved with carbon fibre radiators; and a silicon-tungsten imaging calorimeter made up of layers of tungsten absorbers and silicon detector planes. A time-of-flight system and anti-coincidence counters complete the PAMELA equipment. In the past years, tests have been done on each subdetector of PAMELA; the main results are presented and their implications on the anti-particles identification capability in cosmic rays are discussed here.
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