M. Österlund

Light‐Ion Production in the Interaction of 96 MeV Neutrons with Silicon

Double-differential cross sections for light-ion (p, d, t, He and α) production in oxygen, induced by 96 MeV neutrons are reported. Energy spectra are measured at eight laboratory angles from 20◦ to 160◦ in steps of 20◦. Procedures for data taking and data reduction are presented. Deduced energydifferential and production cross sections are reported. Experimental cross ∗Corresponding author, Tel. +46 18 471 6850, Fax. +46 18 471 3853, E-mail: stephan.pomp@tsl.uu.se

Analysis of polyomavirus enhancer-effect on DNA replication and early gene expression☆

The polyomavirus enhancer is located adjacent to the origin of DNA replication and the transcriptional promoters. It has a cis-acting essential function in the initiation of both viral DNA synthesis and early transcription. The enhancer is activated by the binding of protein factors to specific sites in DNA. Mutants with deletions of the A- or the B-segment of the enhancer were constructed. In mouse 3T6 cells, the transcription of the viral early region was significantly decreased by deletion of the A-segment, but not by deletion of the B-segment. In contrast, the two deletions had a similar, moderately negative effect on viral DNA synthesis. However, the presence of DNA with a wild-type enhancer in doubly transfected cells resulted in very strong interference with the replication, but not with the transcription, of deletion mutant DNA. DNA of the deletion mutants were subjected to site-directed mutagenesis of the remaining enhancer segment. Three non-viable mutants were isolated. All three had base-pair changes in the A-segment affecting immediately adjacent binding sites of cellular protein factors. The mutants had lost the enhancer activity on the early promoter, but only one of them with multiple base substitutions had lost the capacity of DNA replication. Together, the results suggest that different aspects of enhancer function determine the activity in initiation of transcription and replication.

Total Monte Carlo evaluation for dose calculations

Total Monte Carlo (TMC) is a method to propagate nuclear data (ND) uncertainties in transport codes, by using a large set of ND files, which covers the ND uncertainty. The transport code is run multiple times, each time with a unique ND file, and the result is a distribution of the investigated parameter, e.g. dose, where the width of the distribution is interpreted as the uncertainty due to ND. Until recently, this was computer intensive, but with a new development, fast TMC, more applications are accessible. The aim of this work is to test the fast TMC methodology on a dosimetry application and to propagate the (56)Fe uncertainties on the predictions of the dose outside a proposed 14-MeV neutron facility. The uncertainty was found to be 4.2 %. This can be considered small; however, this cannot be generalised to all dosimetry applications and so ND uncertainties should routinely be included in most dosimetry modelling.

Neutron and Light Charged Particle Production in Neutron or Proton-induced Reaction on Iron, Lead and Uranium at Intermediate Energy (20 to 200 MeV) - The HINDAS Collaboration

Neutron and Light Charged Particle Production in Neutron or Proton-Induced Reactions on Iron, Lead and Uranium at Intermediate Energy (20 to 200 MeV) : The HINDAS Collaboration

A Novel Fast Neutron Detector for Nuclear Data Measurements

Accelerator driven system will use a heavy element target such as lead. Many calculations are available to simulate high-energy spallation neutron induced reactions, but little data are available for comparison with the simulations. In order to constrain the simulation tools we have measured (n,Xn) double differential cross section on different targets at The Svedberg Laboratory, Uppsala, Sweden. For neutron energy above 40 MeV, we have developed a novel detector, CLODIA, based on proton recoil and drift chambers to determine neutron energy. CLODIA (Chamber for LOcalization with DrIft and Amplification) is able to track recoil protons with energy up to 90 MeV with spatial resolution of about one millimeter and a detection efficiency of 99% for each drift chamber. Using CLODIA coupled with the SCANDAL set-up, we have been able to measure double differential (n,Xn) cross section on lead and iron for incident neutron energy in the 40-95 MeV energy region.