| 1. |
- Armijo, V., et al.
(författare)
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A fast MWPC with cathode strips and utilizing CF4-isobutane
- 1991
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 303:2, s. 298-308
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Tidskriftsartikel (refereegranskat)abstract
- A planar wire chamber has been developed at LAMPF as a prototype for wire chambers of cylindrical configuration for electron detection in the MEGA experiment. Results form tests with the planar chamber have been used to set the geometrical parameters and predict the performance characteristics of the cylindrical chambers. The behavior of the planar chamber with CF4-isobutane gas demonstrates that 15 μm wire of 1 mm pitch is practical, that lifetimes greater than 0.045 C/cm are achievable and that gate widths of 25 ns are possible. © 1991.
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| 2. |
- Calén, H., et al.
(författare)
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Detector setup for a storage ring with an internal target
- 1996
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 379:1, s. 57-75
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Tidskriftsartikel (refereegranskat)abstract
- A detector setup for the cooler storage ring CELSIUS is described. The setup detects particles produced in interactions between the internal beam and a cluster-jet target. Particles emitted in the forward direction are measured by means of arrays of plastic scintillators and proportional counters. Particles, particularly photons, emitted more isotropically are measured by means of two calorimeters containing CsI(Na) crystals. The performance of the setup is given for neutral meson production in proton-proton and proton-deuteron interactions in the energy range 290-1360 MeV.
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| 3. |
- Cederkall, J, et al.
(författare)
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Relative enhancement of weak two-neutron exit channels in heavy-ion induced fusion-evaporation reactions
- 1997
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 385:1, s. 166-170
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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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| 4. |
- Cederwall, Bo, et al.
(författare)
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MEASUREMENT OF ULTRA-FAST GAMMA-RAY TRANSITIONS FROM HEAVY-ION COMPOUND NUCLEUS REACTIONS
- 1995
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 354:2-3, s. 591-594
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Tidskriftsartikel (refereegranskat)abstract
- A method for correcting target-thickness-induced Doppler broadening in gamma-ray spectra from weakly populated, very short-lived (femtosecond) states is presented. The method is illustrated by an analysis of superdeformed transitions in Dy-152,Dy-153 for which the validity of the procedure could be verified consistently from previous lifetime measurements in Dy-152. Furthermore, estimates of the superdeformed lifetimes, previously not measured in Dy-153, are obtained.
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| 5. |
- Cooper, M. D., et al.
(författare)
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Construction and performance of MEGA's low-mass, high-rate cylindrical MWPCs
- 1998
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 417:1, s. 24-49
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Tidskriftsartikel (refereegranskat)abstract
- A design for extremely low mass, high-resolution multiwire proportional chambers (MWPC) was achieved by the MEGA collaboration in its experiment to search for the lepton family number violating decay μ → eγ. To extend the present branching ratio limit by over an order of magnitude, these MWPCs were operated in high particle fluxes. They showed minimal effects of aging, and evidenced spatial and energy resolutions for the orbiting positrons from muon decay which were consistent with our design parameters. The unique features of these chambers, their assembly into the MEGA positron spectrometer, and their performance during the experiment are described in this paper.
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| 6. |
- Fröjdh, Christer, 1952-, et al.
(författare)
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New sensors for dental X-ray imaging
- 1999
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 434:1, s. 24-29
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Ghetti, R, et al.
(författare)
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Influence of cross-talk rejection procedures on two-neutron intensity interferometry.
- 1999
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 421:3, s. 542-551
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates the effects of a cross-talk rejection procedure on the two-neutron correlation function. The rejection method relies only upon simple kinematic relations between the energy of the detected neutrons and can be applied to commonly used detector configurations. It is demonstrated that the comparison of a cross-talk corrected correlation function with the theory is meaningful as long as the cross-talk rejection procedure and the response of the detector filter are consistently incorporated into the theoretical calculations.
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| 8. |
- Rodushkin, Ilya, et al.
(författare)
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Determination of plutonium concentrations and isotope ratios in environmental samples with a double-focusing sector field ICP-MS
- 1999
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 423:2-3, s. 472-479
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Tidskriftsartikel (refereegranskat)abstract
- An analytical method for the ultratrace and isotopic analysis of plutonium in sediment samples using a double focusing sector field ICP mass spectrometer (ICP-SMS) is described. A detection limit for plutonium in the sub-fg ml-1 range was achieved. The ICP-SMS results were in acceptable agreement with alpha spectrometry. At the low fg ml-1 level a precision in isotope ratio measurements of 2-10% RSD was achieved. Accuracy of the results was assessed by 238U/235U and 205Tl/203Tl isotope ratio determinations using isotopic standards and a natural Tl standard solution, respectively. It was shown that correction for 238UH+ and 238UH2+ is necessary for both plutonium concentration and isotopic composition determinations. From a practical standpoint, the use of ICP-SMS for plutonium measurements is an attractive alternative to techniques such as alpha spectrometry and thermal ionization mass spectrometry (TIMS) due to its higher throughput and ability to measure both concentration and isotopic ratio on the same sample.
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| 9. |
- Stanislaus, S., et al.
(författare)
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Results from beam tests of MEGA's low-mass, high-rate cylindrical MWPCs
- 1992
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 323:1-2, s. 198-202
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Tidskriftsartikel (refereegranskat)abstract
- One of the leading experimental projects at LAMPF has been the MEGA experiment. This is an experiment to search for the rare decay μ → eγ with a sensitivity of 10-13. A prime component of this project has been the design and construction of high-rate, low-mass MWPCs for the tracking of positrons from muon decay. With rate capabilities of 2 × 104 e+/mm2/s and a thickness of 3 × 10-4 radiation lengths, these chambers are state-of-the-art cylindrical MWPCs. Cylindrical chambers of this size (0.9 m2) and thinness have never been previously constructed. The MEGA project at LAMPF has recently succeeded in building chambers with these necessary performance characteristics as demonstrated by data taken from muon decays, cosmic rays, and sources. © 1992.
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| 10. |
- van der Marel, J, et al.
(författare)
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Backtracking as a way to reconstruct Compton scattered gamma-rays
- 1999
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 437:2-3, s. 538-551
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Tidskriftsartikel (refereegranskat)abstract
- A method has been developed to reconstruct the tracks of gamma-rays that have undergone Compton scattering in a high-resolution detector system. The development of this method is focussed on applications in nuclear gamma-ray spectroscopy. In nuclear in-beam gamma-ray spectroscopy a number of (position-sensitive) germanium detectors are placed around a target where the nuclei under investigation are produced. The gamma-rays emitted by the nuclei can have energies up to several MeVs. The nuclear reactions in the target can cause emission of up to 25 coincident gamma-rays and sometimes even more. In order to resolve the individual gamma-rays from such events the detector systems currently under development will have such a high granularity that the energy of scattered gamma-ray will be deposited in several different detector segments. Therefore, in order to determine the initial energies and the first interaction positions, the tracks have to be reconstructed. The reconstruction method presented in this paper is based on the observation that the energy deposition of the final photoelectric interaction after scattering usually falls in a narrow energy band. Starting from points in this energy range attempts are made to reconstruct the tracks using the photoelectric and Compton interaction probabilities and the Compton scattering formula. The method has been tested on simulated events with up to 25 coincident gamma-rays of various energies and with different detector position resolutions. Reconstruction efficiencies of up to 84% have been achieved. (C) 1999 Elsevier Science B.V. All rights reserved.
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