Simon Philip Platt

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.

Charge-Collection and Single-Event Upset Measurements at the ISIS Neutron Source

Charge-collection measurements at the VESUVIO instrument at ISIS are described. Neutron SEU cross sections in SRAM-based FPGAs are measured. Results are compared to equivalent data from Los Alamos Neutron Science Center ICE House. The rate of single-event effects due to fast neutrons at VESUVIO is approximately 15% of that at LANSCE. In addition there is a strong thermal and epithermal component, sufficient to cause many events in devices containing small amounts of 10B. The effects of low-energy neutrons on a commercial CCD contaminated with traces of 10B are described. Cadmium shielding is found to be incompletely effective in separating the effects of fast and slow neutrons, and the implications for testing protocols and instrument design are discussed.

Development and application of a neutron sensor for single event effects analysis

The development and application of a charge-coupled device (CCD) sensor for neutron detection is described. The sensor provides images of neutron-induced single-event effects (SEEs) at 9 μm pixel resolution and a charge/pixel resolution of typically 36.6 electronic charges. Example results are presented, showing the charge profiles resulting from single events observed during tests in a representative neutron spectrum. The sensor enables aspects of SEE phenomena to be studied directly in more detail than hitherto.

Application of Imaging Systems to Characterization of Single-Event Effects in High-Energy Neutron Environments

We use charge-coupled devices (CCDs) to characterise the single-event effect (SEE) inducing properties of high-energy neutron beams, including the spatial distribution of induced charge. Three representative CCD types are evaluated for this purpose. We study the significance of anti-blooming structures and pixel size. Anti-blooming structures are found to suppress event rates and corrupt event statistics. Devices without such structures are preferred and anti-blooming correction is performed in software. A CCD with 9 mum pixels is chosen for an Imaging SEE Monitor, which is currently being deployed in a variety of natural and synthetic neutron fields. Comparison is made between effects observed in neutron beams at LANSCE and TRIUMF accelerator facilities. Cross-sections for all events at the two facilities agree, providing independent confirmation of dosimetry. Cross-sections for more intense events disagree, with about a factor of 5 difference (LANSCE more effective) at 1 pC deposited charge. We attribute this discrepancy to the harder neutron spectrum at LANSCE, and conclude that predictions of SEE cross-sections in devices of interest, as measured at the two facilities, are liable to differ for this reason. Predictions of SEE rates in the field may also be in doubt. Charge collection measurements are recommended for adoption in test protocols for accelerated testing for neutron SEE

Fidelity of energy spectra at neutron facilities for single-event effects testing

We quantify the fidelity of neutron beam spectra for single-event effects accelerated testing. Beam spectra are folded with representative SEE cross-section curves and errors in predicted SEE rates are determined. The use of quasi-monoenergetic neutrons to complement spallation neutron sources is described. Errors can be controlled to insignificant levels even when the maximum neutron energy is below 200MeV.

SEE-inducing effects of cosmic rays at the High-Altitude Research Station Jungfraujoch compared to accelerated test data

We analyse the SEE-inducing effects of cosmic rays using scientific CCDs and make direct comparison of results obtained in the natural cosmic ray field at altitude with those from accelerated test in neutron beams.

ANITA — a new neutron facility for accelerated SEE testing at the svedberg laboratory

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

Modelling Neutron Interactions in the Imaging SEE Monitor

Geant4 is used to simulate neutron interactions in an Imaging Single-Event Effect Monitor. Results are compared to measured data gathered during accelerated testing in neutron beams and during exposure to the cosmogenic neutron field.

Factors impacting the temperature dependence of soft errors in commercial SRAMs

We performed neutron and alpha-particle irradiation to reproduce the effects of the terrestrial environment on several commercial SRAMs manufactured by different vendors. We observed that, depending on the tested vendor, the number of errors either increases or slightly decreases for rising temperature, even in devices belonging to the same technology node. SPICE simulations were then used to investigate the temperature dependence of parameters like the feedback time and restoring current of the cell. The shape and magnitude of the particle-induced transient current was discussed as a function of temperature. The variability in the temperature response was attributed to the balance of contrasting factors, such as cell slowing down and increased diffusion collection with increasing temperature.

Modeling Neutron Interactions and Charge Collection in the Imaging Single-Event Effects Monitor

An enhanced model of our Imaging Single-Event Effects Monitor (ISEEM) is described with validation against experimental data from irradiation in neutron beams. Quantified discrepancies between simulated and experimental results are close to measurement uncertainties.