C.M. Castaneda

Single-Event Upsets and Multiple-Bit Upsets on a 45 nm SOI SRAM

Experimental results are presented on single-bit-upsets (SBU) and multiple-bit-upsets (MBU) on a 45 nm SOI SRAM. The accelerated testing results show the SBU-per-bit cross section is relatively constant with technology scaling but the MBU cross section is increasing. The MBU data show the importance of acquiring and analyzing the data with respect to the location of the multiple-bit upsets since the relative location of the cells is important in determining which MBU upsets can be corrected with error correcting code (ECC) circuits. For the SOI SRAMs, a large MBU orientation effect is observed with most of the MBU events occurring along the same SRAM bit-line; allowing ECC circuits to correct most of these MBU events.

MEASUREMENT OF PROTON PRODUCTION CROSS SECTIONS OF 10BE AND 26AL FROM ELEMENTS FOUND IN LUNAR ROCKS

Cosmic rays penetrate the lunar surface and interact with the lunar rocks to produce both radionuclides and stable nuclides. Production depth profiles for long-lived radionuclides produce in lunar rocks are measured using Accelerator Mass Spectrometry (AMS). For a particular radionuclide these production depth profiles can be interpreted to give an estimate for the solar proton flux over a time period characterized by the half life of the radionuclide under study. This analysis is possible if and only if all the cross sections for the interactions of all cosmic ray particles with all elements found in lunar rocks are well known. In practice, the most important cross sections needed are the proton production cross sections, because 98% of solar cosmic rays and {similar_to}87% of galactic cosmic rays are protons. The cross sections for the production of long-lived radionuclides were very difficult to measure before the development of AMS and only in recent years has significant progress been made in determining these essential cross sections. Oxygen and silicon are major constituents of lunar rocks. We have reported already {sup 14}C production cross sections from O and Si for proton energies 25-500 MeV, and O(p,x){sup 10}Be from 58 160 MeV[6]. Here we present new measurements for the cross sections O(p,x){sup 10}Be,O(p,x){sup 7}Be, Si(p,x){sup 7}Be,Si(p,x){sup 26}Al, and Si(p,x){sup 22}Na from {approximately}30 - 500 MeV.

Radiation resistance of electro-optic polymer-based modulators

Mach–Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation.

A multiple sampling ionization chamber (MUSIC) for measuring the charge of relativistic heavy ions

A large area (1 m × 2 m) multiple sampling ionization chamber (MUSIC) has been constructed and tested. The MUSIC detector makes multiple measurements of energy “loss”, dE/dx, for a relativistic heavy ion. Given the velocity, the charge of the ion can be extracted from the energy loss distributions. The widths of the distributions we observe are much narrower than predicted by Vavilovs theory for energy loss while agreeing well with the theory of Badhwar which deals with the energy deposited. The versatile design of MUSIC allows a variety of anode configurations which results in a large dynamic range of charge. In our tests to date we have observed charge resolutions of 0.25e fwhm for 727 MeV/nucleon 40A and 0.30e fwhm for 1.08 GeV/nucleon 139La and 139La fragments. Vertical position and multiple track determination are obtained by using time projection chamber electronics. Preliminary tests indicate that the position resolution is also very good with α ≅ 100 μm.

Excitation of analogue isovector resonances via the (n, p) reaction at 60 MeV?

The (n,p) charge-exchange reaction is used as a selective tool for studying T+1 isovector excitations. Here, 60 MeV neutrons have been used to measure (n,p) spectra from a range of nuclei. For 6Li and 7Li large components of l=1 dipole strength, not seen in photoneutron data, have been found at higher excitation. In the cases of 6Li, 12C and 16O comparison with photonuclear and (d,2He) data indicates that most of the l=1 strength appears to be s=0. Gamow-Teller (GT)-type transitions have been measured in 6Li, 12C and 28Si and a measure of nu sigma tau , the isovector spin-dependent component of the effective nucleon-nucleon interaction, has been obtained at 60 MeV. In the Ni isotopes, increasing blocking of the GDR with N-Z is seen. A structure of substantial strength in 209Bi(n,p)209Pb, originally thought to be isovector quadrupole, may more probably be evidence of a 2h(cross) omega sigma tau -type excitation.

Proton production cross sections for 14C from silicon and oxygen: implications for cosmic-ray studies

Abstract The production rates of 14 C from proton spallation of silicon and oxygen have been measured over a wide range of energies from 31 to 450 MeV. 14 C was measured by accelerator mass spectrometry (AMS) after extraction of carbon from the samples by melting in a flow of oxygen.

Criticality of Low-Energy Protons in Single-Event Effects Testing of Highly-Scaled Technologies

We report low-energy proton and low-energy alpha particle SEE data on a 32 nm SOI CMOS SRAM that demonstrates the criticality of using low-energy protons for SEE testing of highly-scaled technologies. Low-energy protons produced a significantly higher fraction of multi-bit upsets relative to single-bit upsets when compared to similar alpha particle data. This difference highlights the importance of performing hardness assurance testing with protons that include energy distribution components below 2 MeV. The importance of low-energy protons to system-level single-event performance is based on the technology under investigation as well as the target radiation environment.

Measuring excitation functions needed to interpret cosmogenic nuclide production in lunar rocks

Radionuclides produced in lunar rocks by cosmic ray interactions are measured using Accelerator Mass Spectrometry or gamma-ray spectroscopy. From these measurements, estimates of the solar proton flux over time periods characterized by the half-life of the isotope under study can be made, if all the cross sections for all the reactions of all cosmic ray particles with all elements found in lunar rocks are known. Proton production cross sections are very important because ∼98% of solar cosmic rays and ∼87% of galactic cosmic rays are protons in the lunar environment. Many of the needed cross sections have never been measured. Targets of C, Al, Si, SiO2, Mg, K, Ca, Fe and Ni have been irradiated using three accelerators to cover a proton energy range of 25–500 MeV. Excitation functions for 7Be, 10Be, 22Na, and 26Al production from Mg and Al will be reported, and the consequences of using these new cross section values to estimate solar proton fluxes discussed.

The response of NaI(T1) to 30−60 MeV Z = 1 particles

Abstract Measurements are reported for the light output response on a NaI(T1) detector for protons, deuterons, and tritons with energies between 30 and 60 MeV. The stopping power region covered by this data overlaps previous data taken with electrons and protons. The new data around 60 MeV is interesting in that the light output is greater for deuterons (and tritons) than that for protons by the equivalent of ≈ 1 MeV. A comparison is made with the model of Murray and Meyer for light output response in inorganic crystals.

Experimental cross-sections for the production of 10Be from natural carbon targets with 40.6 to 500 MeV protons

Abstract Cross-sections for the production of 10Be from natural carbon targets were measured for proton energies ranging from 40.6 to 500 MeV. The yield of 10Be in each target was determined using accelerator mass spectrometry. The values of these new cross-sections ranged from 0.164 to 2.75 mb and confirmed previously published data in this energy range.