Jan Blomgren

Neutron induced single-word multiple-bit upset in SRAM

The single-word multiple-bit upset (SMU) frequency for nine commercial static random access memories (SRAM) have been evaluated at eight different neutron energies; 0-11 MeV, 14 MeV, 22 MeV, 35 MeV, 45 MeV, 75 MeV, 96 MeV, 160 MeV. The SRAM types used at these experiments have sizes from 256 Kbit up to 1 Mbit, with date-codes ranging from 9209 up to 9809. The result showed a slightly rising dependence on the neutron energy. Also experiments at two neutron energies, 45 MeV and 96 MeV, were performed where the supply voltage influence on the SMU-rate was studied. Five device types were used at 96 MeV and the supply voltage was changed between 5 V, 3.3 V and 2.5 V. At 45 MeV three devices at 5 V and 3.3 V were irradiated. The experiments showed a relation between the amount of total upset and SMU that indicates no clear supply voltage dependence.

A facility for studies of neutron-induced reactions in the 50–200 MeV range

A facility for studies of neutron-induced reactions has been built at the upgraded Gustaf Werner cyclotron of the The Svedberg Laboratory, Uppsala, Sweden. Well-collimated, monoenergetic neutron beams are produced with a fairly long distance between the neutron source and the reaction target, to reduce background radiation. A magnetic spectrometer with large angular and momentum acceptance has been constructed to allow measurements of energy and angular distributions of light ions produced in neutron-induced reactions. Initially, studies will be undertaken of isovector monopole and Gamow-Teller resonances, induced by the (n,p) reaction in various nuclei. The performance is illustrated in a measurement of the doubly differential cross section of the 12C(n,p)12B reaction at 100 MeV.

Characterization of the ANITA Neutron Source for Accelerated SEE Testing at the Svedberg Laboratory

ANITA ( Atmospheric-like Neutrons from thIck TArget), a new neutron facility for accelerated testing of components and systems for single event effects, has been put into operation at The Svedberg Laboratory in Uppsala, Sweden. Results of beam characterization measurements are reported.

The 54,56Fe(n, p)54,56Mn reactions at En = 97 MeV

Abstract Double-differential cross sections of the 54,56Fe(n, p) reactions have been measured at 97 MeV in the angular range 0–30° for excitation energies up to 40 MeV. The spectra have been decomposed into different multipolarities by a technique based on the use of sample angular distributions calculated within the distorted-wave Born approximation. From the identified Gamow-Teller strength, Sβ+ values were obtained for 54Fe and 56Fe. Comparisons with available shell-model calculations of the GT strength were made. The results are important for models of supernova explosions since electron-capture rates, which are proportional to Sβ+, in 1f2p-shell nuclei affect the dynamics of the star. At higher excitation energies, the spectra are dominated by L = 1 strength in broad distributions with a maximum at about 12 MeV. Microscopic calculations based on the random-phase approximation were performed and compared with the experimental data.

Energy-resolved neutron SEU measurements from 22 to 160 MeV

The energy dependence of the neutron-induced single-event upset (NSEU) cross section for Static RAMs have been measured, using quasi-monoenergetic neutrons of five different energies from 22 to 160 MeV. The measured SEU cross sections were corrected for the low-energy neutron tail by an iterative folding procedure. A clear energy dependence has been found. The SEU rate has been compared both with results from testing with a neutron spallation spectrum up to 800 MeV and the measured SEU rate from In-Flight experiments at 20 km.

Nucleon-induced reactions at intermediate energies: New data at 96 MeV and theoretical status

Double-differential cross sections for light charged particle production (up to A=4) were measured in 96 MeV neutron-induced reactions, at the TSL Laboratory Cyclotron in Uppsala (Sweden). Measurements for three targets, Fe, Pb, and U, were performed using two independent devices, SCANDAL and MEDLEY. The data were recorded with low-energy thresholds and for a wide angular range (20 deg. -160 deg. ). The normalization procedure used to extract the cross sections is based on the np elastic scattering reaction that we measured and for which we present experimental results. A good control of the systematic uncertainties affecting the results is achieved. Calculations using the exciton model are reported. Two different theoretical approaches proposed to improve its predictive power regarding the complex particle emission are tested. The capabilities of each approach is illustrated by comparison with the 96 MeV data that we measured, and with other experimental results available in the literature.

A facility for measurements of nuclear cross sections for fast neutron cancer therapy

A facility for measurements of neutron-induced double-differential light-ion production cross-sections, for application within, e.g., fast neutron cancer therapy, is described. The central detectio ...

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

Problem-Based Distance Learning of Energy Issues via Computer Network.

Problem‐based learning (PBL) modified for distance education (PBDiL = Problem‐Based Distance Learning) has been used for teaching energy issues at Uppsala University, Sweden. Collaborative learning in groups of seven to eight students was enabled by computer communication and enhanced the use of Internet. Two different teaching methods have been tried and are compared, both being influenced by methods used in conventional face‐to‐face PBL. The problem presentation was entirely built on pictures, and examination through student reports was successful. A student remark, ‘I study on my own but yet not alone’ shows the importance of social contact.

The New Uppsala Neutron Beam Facility

A new quasi‐monoenergetic neutron beam facility has been constructed at the The Svedberg Laboratory (TSL) in Uppsala, Sweden. Key features include an energy range of 20 to 175 MeV, high fluxes, and the possibility of large‐area fields. Besides cross‐section measurements, the new facility has been designed specifically to provide optimal conditions for testing of single‐event effects in electronics and for dosimetry development. First results of the beam characterization measurements performed in early 2004 are reported.