No abstract available

[en] Three tree core samples of Norway spruce (Picea Abies) have been analysed by PIXE. The concentration profiles for 17 elements heavier than sodium have been determined by means of one PIXE measurement every 2 mm along the samples. The samples were collected at Faexboda, an experimental area north of Uppsala where artificially acidified and limed environmental experiments are made. One sample from each of an acidified, a limed and a reference area has been collected. The main interest is focused on potassium, calcium, manganese, iron, copper and zinc. All three samples have about the same concentration profile in the heartwood. Large differences are observed in the sapwood. In the sample from the limed area the calcium content is much higher and the iron and chromium contents are lower than in the sample from the reference area. In the sample from the acidified area the calcium and potassium contents are lower and the manganese, iron and chromium contents are much higher than in the sample from the reference area. The observed concentration profiles of trace elements in trees indicate that changes in the environment due to acidification can be quantified at an early stage by means of PIXE. (author)

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No abstract available

[en] A time to digital converter (TDC) with a time resolution of 1 ns has been designed. The deadtime is T+0.6 μs where T is the measured time. The time range can be preselected between 0.3 and 10 μs. The TDC has one START and three mutually exclusive STOP inputs which accept standard pulses (-16 mA). The time information is presented as a bit binary word, including the activated stop input address. The instrument has been successfully used in μ⁺SR (muon spin rotation) measurements and has proven itself advantageous over the more common TAC+ADC combination. (Auth.)

[en] In Cu and Nb positive muons 'freeze in' at temperatures below 90K and 60K respectively, whereas in Al where they show high mobility all over the range 1-700K. The possible spatial extension of the muons and the effects of strong EFG's at neighbouring nuclei are discussed. (Auth.)

[en] Muon precession frequencies were studied in polycrystalline antimony in the temperature range 2 K-300 K in an applied field of 0.4 kG. Data for applied fields of 0.8 kG and 2.1 kG were also obtained at a few temperatures. Single crystal experiments were also performed. The frequency shift and its field and temperature dependences were studied. (Auth.)

No abstract available

[en] The muon depolarization rate was studied in Nb at low temperature in order to show the sensitivity of muon propagation to imperfections