N Olsson

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.

Soft error rate increase for new generations of SRAMs

We report on enhanced susceptibility for neutron-induced soft errors from accelerated testing of static random access memories (SRAMs), performed at Los Alamos National Laboratory. This enhancement is per bit of memory.

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.

A comparative study between two neutron facilities regarding SEU

We report on a comparative study between two neutron facilities used for SEU studies, namely the Weapons Neutron Research facility at Los Alamos National Laboratory (a white neutron source), and the The Svedberg Laboratory in Sweden (a quasimono-energetic neutron source). The soft error rates generated from TSL are in excellent agreement with those from WNR. Moreover, an increase of the SER for small process technologies was observed.

SEUs Induced by Thermal to High-Energy Neutrons in SRAMs

We report on experimental SEU studies using thermal and high-energy neutrons, conducted at the TRIUMF facility, Vancouver. Different SRAM samples were used and many samples showed to be highly susceptible to thermal neutrons. Moreover, a considerable part of the total SEU-rate, at high altitudes as well as down at sea level, may be attributed to thermal neutrons for RAM based devices

A Comparative Study between Proton and Neutron Induced SBUs in SRAMs

We report on irradiation induced SEU by high-energy protons and neutrons. The experiments were performed at The Svedberg Laboratory in Uppsala, Sweden, and at the Weapons Neutron Research (WNR) facility, in Los Alamos, USA. A wide range of SRAMs were used to study the differences between proton and neutron induced SEUs at different energies.

Elastic neutron scattering at 96 MeV from {sup 12}C and {sup 208}Pb

A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL, has recently been installed at the 20-180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from {sup 12}C and {sup 208}Pb has been studied at 96 MeV in the 10 deg. -70 deg. interval. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions based on phenomenology or microscopic nuclear theory.

Elastic neutron scattering at 96 MeV

A facility for detection of scattered neutrons in the energy interval 50–130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20 – 180‐MeV neutron beam line of The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12C, 16O, 56Fe, 89Y, and 208Pb has been studied at 96 MeV in the 10 – 70° interval. The results from 12C and 208Pb have recently been published,6 while the data from 16O, 56Fe, and 89Y are under analysis. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron‐induced differential cross section measurement on a nuclear target. The results are com...

On Nuclear Structure Effects in the Nucleon‐Induced Fission Cross Sections of Nuclei near 208Pb at Intermediate Energies

On Nuclear structure Effects in the Nucleon-Induced Fission Cross Sections of Nuclei Near Pb-208 at Intemediate Energies

Cross Section Data and Kerma Coefficients at 95 MeV Neutrons for Medical Applications

Motivated by the need of data on neutron-induced reactions with biologically relevant materials, e.g., carbon and oxygen, we have constructed and installed the MEDLEY detector array at the neutron beam facility of the The Svedberg Laboratory in Uppsala. The central detection elements of MEDLEY are three-detector telescopes, consisting of two silicon detectors and a Csl crystal. To cover wide energy and angle ranges, we have mounted eight such telescopes at 20° intervals. We have used ΔE − ΔE − E techniques to obtain good particle identification for protons, deuterons, tritons, 3He and α particles over an energy range from a few MeV up to 100 MeV. To define the detector solid angle, plastic scintillators were employed to serve as active collimators. We have up to now measured double-differential cross sections of inclusive light-ion production induced by 95 MeV neutrons on carbon and oxygen. From these data production cross sections, as well as partial kerma coefficients, are being determined. We have found that especially the proton kerma coefficient for carbon is substantially larger than that of a recent evaluation, leading to a larger total kerma coefficient. The obtained data supports a trend observed for similar data at lower energies.