K. Takahisa

SEILA: Soft error immune latch for mitigating multi-node-SEU and local-clock-SET

We have developed a robust latch for achieving high reliability in LSI. The latch can attenuate multi-node single-event-upset (MNSEU) and single event transient on local-clock (SETLC). The robust latch has Dual-clock-buffers (DCB) and Double-height-cell (DHC) technologies. Results on neutron acceleration experiments show that DHC can dramatically attenuate MNSEU and DCB can protect almost SETLC of the latch. In addition, we investigate optimum design in well structure.

Evaluation of the White Neutron Beam Spectrum for Single-Event Effects Testing at the RCNP Cyclotron Facility

Abstract The 30-deg white neutron beam at the Research Center for Nuclear Physics (RCNP) cyclotron facility has been characterized as a probe suitable for testing of single-event effects (SEE) in semiconductor devices in the neutron energy range from 1 to 300 MeV using the 392-MeV proton incident reaction on a 6.5-cm-thick tungsten target. The neutron spectrum obtained by time-of-flight measurements reproduced the terrestrial neutron flux distribution at sea level, and neutron intensity increased by a factor of 1.5 × 108 became available. The average neutron intensity and spectrum in the energy region from 10 to 100 MeV at RCNP were almost the same as those at the Weapons Neutron Research (WNR). The calculated RCNP neutron flux using Particle and Heavy Ion Transport code System (PHITS) generally agreed with the measured RCNP data within a factor of 2. The neutron density per pulse at RCNP, which is around 500 times lower than that for WNR, has the advantage in reduction of the pileup probability of single-event transient currents and false multiple-bit upsets. Such conditions at RCNP are suitable for accelerated SEE testing to get meaningful results in a realistic time frame.

Precise measurement of the cross section ofHe3(He3,2p)He4by usingHe3doubly charged beam

The fusion cross section of 3He(3He,2p)4He at a center of mass energy of 30 to 50 keV has been measured by using helium-3 doubly ionized beam at a low-energy high current accelerator facility, OCEAN. Free from molecular interference in the beam, the measurement determines the astrophysical S-factor with better statistical and systematical errors than previous data. By using singly and doubly charged helium-3 ions the facility envisages to provide the data from high energy to Gamow energy regions.

A study of nucleon properties in nuclei through (p, 2p) reactions

Abstract The differential cross sections and analyzing powers have been measured for a proton knockout reaction from s 1/2 orbits of several target nuclei aiming at studying nuclear medium effects in the nucleon-nucleon interaction, and in-medium nucleon properties through it. It is confirmed from the cross section data that the reaction mechanism is simple and contribution from the multi-step processes is less than ten percent, only a few percent for a 12 C target case. The analyzing power shows a distinct reduction from the value of the free proton-proton scattering and the target dependence, which is equivalent to the density dependence, of the reduction suggests existence of a medium effect. The study has been extended to the measurement of other spin observables, polarization and spin-transfer coefficients, and a preliminary result is given.

PERFORMANCE OF THE RCNP POLARIZED ION SOURCE

Abstract A new polarized ion source was constructed at RCNP. It employs the cold (∼30 K) atomic beam technology and an electron cyclotron resonance ionizer. The source has been operational since fall in 1994 to provide polarized protons to experimental researches at 200–400 MeV. After the first operation of the source, developments have been performed to increase the long term stability of the source and to improve the beam polarization. The source works for longer than one month before cleaning the dissociator. Proton beam intensity from the source is 50–100 μA and the polarization is 70% or better after acceleration with the K400 RCNP ring cyclotron.

Validation of hardware error recovery mechanisms for the SPARC64 V microprocessor

The SPARC64 V microprocessor is designed for use in high-reliability, large-scale unix servers. In addition to implementing ECC for large SRAM arrays, the SPARC64 V microprocessor incorporates error detection and recovery mechanisms for processor logic circuits and smaller SRAM arrays. The effectiveness of these error recovery mechanisms was validated via accelerated neutron testing of Fujitsupsilas commercial unix server, the PRIMEPOWER 650. Soft errors generated in SRAM arrays were completely recovered by the implemented hardware mechanisms, and only 6.4% of the estimated neutron-induced logic circuit faults manifested as errors, 76% of which were recovered by hardware. From these tests, the soft error failure rate of the SPARC64 V microprocessor due to atmospheric neutron hits was confirmed to be well below 10 FIT.

Highly sensitive radon monitor and radon emanation rates for detector components

Abstract The radon emanation rates for materials were measured by using the electrostatic precipitation method as a radon monitor. It was found that a low level of radon was emanated from several material components in ELEGANT V. The radon monitor has been developed for the highly sensitive measurements of low-level radon concentration. The system was shown to have a sensitivity to radon concentrations as low as 1.6 mBq / m 3 for one day measurement. The system was also used as the radon concentration monitor for the gas inside the airtight box of the ELEGANT V at Oto Cosmo Observatory.

Search for WIMPs with the large NaI(Tl) scintillator of ELEGANT V

Abstract The cold dark matter search has been carried out at Oto Cosmo Observatory with the large volume NaI(Tl) scintillators of ELEGANT V. The new limits on WIMPs could be obtained by the analysis of the annual modulation.

Investigation of multi cell upset in sequential logic and validity of redundancy technique

Purpose of this work is investigation of validity on redundancy techniques for soft-error mitigation in sequential elements such as flop-flops and latches. We have evaluated multi-cell-upset (MCU) in sequential elements through neutron acceleration experiments at Osaka Univ. We have calculated mitigation efficiency of the redundancy technique from the experimental results. MCU ratio increases with technology advancing. Validity of the redundancy technique is kept even on advanced technologies.

(6Li,6He) reaction at 100 MeV/nucleon as a probe of spin-excitation strengths

Abstract For a selective excitation of spin-flip strength, ( 6 Li, 6 He) reactions can be a useful tool, because: a) 6 Li and 6 He have ground-state spin and parity values J π = 1 + and 0 + , respectively; b) 6 He has no particle-stable excited state, thus effects from ejectile excitation can be avoided. The ( 6 Li, 6 He) experiments were performed at 100 MeV/nucleon, at which incident energy the reaction is expected to be single-step dominant. Through the analysis of the good-resolution ( 6 Li, 6 He) data on 13 C, 26 Mg, 27 Al and 58 Ni targets, the evidence for a proportional relationship between 0° cross sections and the corresponding Gamow-Teller transition strengths is examined. Suppression of non-spin flip excitations is discussed based on the hindrance of the excitation of the isobaric analog state.