Ragnar Hellborg

Matrix theory of the motion of a charged particle beam in curvilinear space-time Part I. General theory

Abstract A general relativistic theory of charged particle beam motion along a curved optical axis, including the gravitational field, is important for designers of optimal beam control systems. In this paper, which is the first of two, a new matrix approach is presented. This allows the development of a relativistic matrix theory for charged particle beam motion in the most general case of a curved reference trajectory, including the gravitational force. This approach is based on three basic matrices: the reference frame matrix, the curvature matrix and the electromagnetic matrix. The equations of the particle beam motion and of the electromagnetic field, including the space charge, are given. The notations used is independent of the units of the measured fields and energies. In a second paper, also published in this issue, the matrix and recursive methods for solving the nonlinear equations of motion will be presented.

Levels of 14C in the Terrestrial Environment in the Vicinity of Two European Nuclear Power Plants

Radiocarbon is produced in all types of nuclear reactors. Most of the C-14 released into the environment is in the form of gaseous emissions. Recent data on the C-14 concentration found in terrestrial samples taken in the vicinity of nuclear power plants in Romania and Lithuania are presented. We found increased C-14 levels in the surroundings of both power plants. At the Romanian power plant Cernavoda, we found excess levels of C-14 in grass within a distance of about 1000 in, the highest C-14 specific activity being 311 Bq/kg C (approximately 28% above the contemporary C-14 background) found at a distance of 200 in from the point of release (nearest sampling location). At the Lithuanian power plant Ignalina, samples of willow, pine, and spruce showed a C-14 excess of similar magnitude, while significantly higher values were found in moss samples. The samples were analyzed at the accelerator mass spectrometry facility in Lund, Sweden. (Less)

Advances in targetry with thin diamond-like carbon foils

Thin and stable diamond-like carbon (DLC) foils, which were fabricated at the Kurchatov Institute by sputter deposition, have proved recently to be advantageous for stripping and secondary electron timing of high energy heavy ions in a number of accelerator experiments. This resulted in expanding applications of these DLC foils which necessitated further development efforts directed toward the following applications of DLC targetry: (i) thin stripper foils for lower energy tandem accelerators, (ii) enlarged (up to 66 mm. in diameter) stop foils for improved time-of-flight elastic recoil detection ion beam analysis, and (iii) ultra-thin (about 0.6 mug/cm(2)) DLC foils for some fundamental and applied physics experiments. Along with the fabrication of thin DLC stripper foils for tandem accelerators, much thicker (up to 200 mug/cm(2)) foils for post-stripping of heavy-ion beams in higher energy linacs, are within reach.

Application of accelerator mass spectrometry (AMS) for high-sensitivity measurements of 14CO2 in long-term studies of fat metabolism

Long-term measurements of 14C in CO2 expired after ingestion of 14C-labelled triolein were performed using accelerator mass spectrometry (AMS). About 30% of a given amount of 14C-labelled triolein was catabolized rapidly, while the remaining 70% had a very slow turnover. The study shows the potential of the AMS technique for the study of the long-term biokinetics of 14C-labelled pharmaceuticals. The AMS technique allows the administered activity to be reduced by several orders of magnitude without compromising the study. It may also allow studies of rare drug metabolites.

Biokinetics and radiation dosimetry for patients undergoing a glycerol tri[1-14C]oleate fat malabsorption breath test.

The glycerol tri[1-14C]olein test for fat malabsorption was carried out in two male volunteers and measurements of the loss of 14C in expired air, urine and faeces and the retention of 14C in biopsy samples of abdominal fat were made using accelerator mass spectrometry. Exhalation accounted for 73% and 55% of the administered activity and could be described by three-component exponential functions with halftimes of about 1h, 2 days and 150 days, respectively. Urinary excretion accounted for 24% of the administered activity, almost all during the first 24h after administration; about 2% was excreted in the faeces in 48h. The halftime of retention of 14C in fat ranged from 137 to 620 days. Absorbed dose calculations indicate that for a normal adult the largest dose, 1.5-7.0mGy/MBq is received by the adipose tissue, and that the effective dose is 0.3-0.5mSv/MBq. It is concluded that no restrictions need to be placed on radiation safety grounds on the administration of 0.05-0.1MBq 14C-triolein for the triolein breath test.

Environmental levels of carbon-14 around a Swedish nuclear power plant measured with accelerator mass spectrometry

Abstract 14 C is one of the radionuclides which are produced by nuclear power plants. The main part of the 14 C, which is released during normal operation, is produced through neutron induced reactions in the cooling water and is released as airborne effluents (such as CO 2 and hydrocarbons) through the ventilation system of the plant to the surrounding environment. Because of the biological importance of carbon and the long half-life of 14 C, it is of interest to measure the releases and their incorporation into living material in the environment of the power plants. In this pilot study the accelerator mass spectrometry (AMS) facility at the University of Lund has been used to measure the 14 C activity concentration in vegetation around a Swedish nuclear power plant. AMS is suitable mainly because of the accuracy obtained within a short measuring time, which makes it possible to analyze a sufficient number of samples for a thorough investigation. The results of this study demonstrate that the AMS method is suitable for investigations of the influence on the local environment of reactor-released 14 C by analysis of living material. To test dispersion models, however, air sampling both of emission source and in the surrounding of the plant seems more suitable.

14C levels in the vicinity of two swedish nuclear power plants and at two clean-air sites in Southernmost Sweden

(super 14) C is one of the radionuclides that are produced to different degrees by neutron-induced reactions in all types of nuclear reactors. Part of the (super 14) C created is continuously released into the surrounding environment during normal operation as airborne effluents in various chemical forms (such as CO (sub 2) , Co and hydrocarbons) through the ventilation system of the plant. Because of the biological importance of carbon and the long half-life of (super 14) C, it is of interest to measure the releases and their incorporation into living material. We report here on the (super 14) C activity concentrations in annual tree rings and the air around two Swedish nuclear power plants, as well as the background (super 14) C activity levels from two reference sites in southern Sweden from 1973-1996. We used both accelerator mass spectrometry (AMS) and decay counting in the investigation.

A new design for the low-energy optics of the Lund Pelletron accelerator

Abstract Several improvements have been implemented on the low-energy side of the Lund 3UDH Pelletron tandem accelerator. We report on the use of an ANIS sputtering source, the installation of a new injector with two legs and the rebuilding of the low-energy optics between sources and accelerator. New lenses have been placed at optimuum positions which, together with a higher pump capacity. increased the beamtransmission. Angular misalignment of the beam has been minimized by repositioning steerers and profile monitors.

Accelerator mass spectrometry at the Lund Pelletron accelerator.

Three years ago, funds were raised to equip the 3 MV Pelletron accelerator at the Department of Physics, Lund University for accelerator mass spectroscopy (AMS). We have modified the accelerator for mass spectroscopy by relocating focusing devices on both the low- and high-energy side of the accelerator and installing a Wien velocity filter and detectors for measuring the particle energy (E) and energy loss (DE). We have been working exclusively with 14C during the initial period. About 40 samples of elemental carbon have been produced, using Fe or Co as catalyst, during the last two years. The 12C- current from these samples is about 3-51uA, using an ANTS sputtering source. We are now planning 14C analyses in the fields of archaeology, Quaternary geology and radioecology.

A one-year study of the total air-borne14C effluents from two Swedish light-water reactors, one boiling water- and one pressurized water reactor

The results of a one-year study of the total air-borne14C effluents from two Swedish light-water reactors, one boiling water reactor (BWR) at Forsmark and one pressurized water reactor (PWR) at Ringhals, are presented. Air emitted from the stacks has been collected continuously over two-week periods and the14C content in the samples has been analysed using accelerator mass spectrometry (AMS). The14C activity concentration in the air issuing from the stack of the PWR varied between 2 and 1132 Bq/m3 with a mean value of 200 Bq/m3, while from the BWR the activity concentration varied between 4 and 146 Bq/m3, with a mean value of 95 Bq/m3. The corresponding14C release rate was 0.27 TBq/GWel·year for the PWR and 0.48 TBq/GWel·year for the BWR. During the same period of time, for comparison, the14C activity in continuously collected air from the stack of the PWR was also measured by liquid scintillation counting. In most cases the results of these measurements were in fair agreement with the corresponding AMS results.