| 1. |
- Burns, M, et al.
(författare)
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Physics aspects of the DELPHI vertex detector
- 1988
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Ingår i: 3rd Topical Seminar on Perspectives for Experimental Apparatus at Future High-energy Machines and Underground Laboratories.
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Konferensbidrag (populärvet., debatt m.m.)
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| 2. |
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| 3. |
- Eriksson, Mikael, et al.
(författare)
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A VUV undulator for MAX
- 1988
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Ingår i: Nuclear Inst. and Methods in Physics Research, A. - 0168-9002. ; 265:3, s. 587-595
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Tidskriftsartikel (refereegranskat)abstract
- An undulator operating at radiation wavelengths between 250 and 2000 Å has been constructed at the Technical Research Centre of Finland and recently installed at the MAX storage ring in Lund. The undulator utilizes ferrite permanent magnets in the hybrid configuration. The magnetic and mechanical design, calculated performance and influence on the electron beam of the undulator are discussed.
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| 4. |
- Helgeson, Ulf, 1943-
(författare)
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Mössbauer studies of electron population in some iron complexes
- 1983
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A Mössbauer effect measuring system has been constructed. With the use of a liquid helium cryostat measurements are performed at room liquid nitrogen and liquid helium temperature. A superconducting magnet with fields up to 5 Tesla has been used in the cryostat. Mossbauer isomer shifts and quadrupole splittings as well as ESCA electron binding energies are reported for a series of iron complexes representing different types of coordination.A method to combine experimental results from Mossbauer, ESCA and IR measurements is used to estimate the electronic population of the valence shell of iron.Occupation numbers for the 3d, 4s and 4p shells are reported for dithiolate complexes, betadiketonates and cyano-, thiocyanato and halogeno-complexes of iron. These valence shell populations are compared to Extended Hückel SCC calculations.
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| 5. |
- Larsson, N. P.O., et al.
(författare)
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Characterization of the response function of a Si(Li) detector using an absorber technique
- 1989
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Ingår i: Nuclear Inst. and Methods in Physics Research, B. - 0168-583X. ; 43:4, s. 574-580
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Tidskriftsartikel (refereegranskat)abstract
- The non-Gaussian response function of a Si(Li) detector has been measured for characteristic Kα X-rays in the energy interval 1.5-8.6 keV using an absorber technique. The method is based on the different response to an attenuating absorber placed in front of the detector for the detector tail as compared to fully absorbed photons in the same position in the spectrum. The shape of the tail of a Kα X-ray peak could be derived from three X-ray spectra acquired with different attenuating absorbers using the PIXE or XRF method for excitation of single element standards. The line shape function could be described by a full energy Gaussian, a shelf, an exponential and a Si-escape component. The results presented are in good agreement with previously reported response functions obtained in measurements of monochromatic X-rays. The results will be implemented in a computer program for evaluating micro-PIXE spectra.
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| 6. |
- Martinsson, Bengt G.
(författare)
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An external beam PIXE/PESA setup for characterization of fine aerosols
- 1987
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Ingår i: Nuclear Inst. and Methods in Physics Research, B. - 0168-583X. ; 22:1-3, s. 356-363
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Tidskriftsartikel (refereegranskat)abstract
- An external beam setup has been developed for the determination of elemental concentrations in fine aerosols (aerodynamic particle diameter less than about 2 μm). Carbon, nitrogen and oxygen are determined with particle elastic scattering analysis (PESA) and, simultaneously, elements heavier than silicon with PIXE at a proton energy of 3.58 MeV. Earlier work on aerosols with PESA and most PIXE work have been performed with the aerosol sample in high vacuum, which causes losses of certain compounds, e.g. several organic substances present in atmospheric aerosols. These losses are increased by the heating effect of the beam. The rate of mass loss of different aliphatic hydrocarbons has been investigated for different chamber gas pressures, chamber gas exchange rates and beam current densities. The external beam approach showed a considerable improvement compared with high vacuum analysis. The external beam setup is described in some detail with respect to geometry, electronics and the chamber gas-handling system.
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| 7. |
- Nordell, Bo, 1945-
(författare)
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Production of photoneutron beams and radionuclides by photonuclear reactions using a 50 MeV racetrack microtron
- 1983
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The feasibility of using electrons accelerated by a 50 MeV racetrack microtron to generate a mixed beam of neutrons and photons for radiation therapy and for production of radionuclides has been investigated.To develop target systems for these purposes the angular distribution and yield of bremsstrahlung from different targets have been studied theoretically. The derived formula is in good agreement with experiments at energies up to 50 MeV and for target materials ranging from Be to W.The penetration of the neutron component of the photoneutron beam was determined by ionisation chambers and the half value depth in tissue equivalent plastics ranged from 4.4 to 5.2 g cm-2 depending on the target material.The photoneutron energy spectra were measured from targets of Sn, Pb and U by a liquid scintillator and the mean energy was between 2 and 2.5 MeV. These results imply that the beam is only useful for treatment of rather superficial tumours. To give a neutron absorbed dose rate of 0.1 Gy min-1 the electron beam current must be greater than 100 microA.Methods for production of 11C and 123l have been developed. The results show that 3 GBq of 11C can be produced with a 40 to 50 MeV electron beam at a mean electron current greater than 50 microA. The yield of 123l is very much dependent on the amount and the degree of enrichment of the 124Xe which is used as target material. With a 100 g 124Xe target 2 GBq can be produced in 2h.
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