Detailed history of recoiling ions induced by nucleons

Nucleons induced failures in microelectronics devices is a real concern for today avionic and space flights. Nucleons are able to trigger nuclear reactions in the device, which is likely to undergo various dysfunctions. The failure is attributed to the nature of the secondary nuclei and their energies, especially to the residual recoiling ion, which can deposit locally the highest amount of energy. To better understand the mechanisms of such failure, but also to develop tools able to predict the reliability of a device in a given environment, the author developed the DHORIN nuclear code, which focuses on the recoil ions induced by nucleons in the 100 keV-200 MeV energy range. DHORIN, which stands for “detailed history of recoiling ions induced by nucleons”, provides the spectra of secondary particles emitted during the nuclear reactions. These spectra are yet required by devices simulators in order to estimate the reliability of a given component. Comparisons of excitation functions given by DHORIN and the EXFOR database are given here for aluminium and silicon.     

Further results from the CDMS experiment

The Cryogenic Dark Matter Search experiment utilizes discriminating detectors where both the recoil energy and ionization produced by each particle event are simultaneously measured. Here we present our latest results from operating 4 Ge (4×250 g) and 2 Si (2×100 g) detectors at the shallow Stanford site. Our new WIMP exclusion limit excludes new parameter space for low-mass WIMPS.     

Neutron Emission,Mass Distribution and Energetics in 14.5 MeV-Neutron Induced Fission of Uranium-238

A study is performed on 14.5 MeV-neutron induced fission of ²³⁸U by means of three-parameter experiment in which the energies of both fragments and the time-of-flight of one fragment are measured. A mosaic-arrayed surface barrier detector of large sensitive area is used at the remote end of a flight tube. The pre- and post-neutron-emission fragment mass distributions are obtained, together with the average total kinetic energy of fragment as a function of its mass. The average number of neutrons emitted from an individual fragment and the average total number of emitted neutrons are also derived as a function of fragment mass. The results agree well with those calculated by the method developed in our laboratory for medium-excitation fission. The average number of emitted neutrons and the mass distribution of fission fragment are derived for the respective reactions of first-, second- and third-chance fission.     

Probing exotic magnetic phases in ferrites with neutrons

The decades of the sixties and early seventies saw the neutron diffraction technique playing a major role in the elucidation of magnetic structures in a variety of ferrites in our laboratory. In 1979, Villain in his seminal paper on insulating spin glasses argued that the spinel structure affords topological frustration which can give rise to a variety of perturbed magnetic ordering, depending upon magnetic dilution in the ferrite. The neutron is a unique probe to explore the nature of spatial correlations of magnetic moments in such systems. This paper describes the exciting work carried out at Trombay recently in mixed ferrites which have led to the discovery of exotic magnetic phases like the uniaxial random ferrimagnetic phase and the canted random ferrimagnetic phase involving the coexistence of long-range magnetic order and disorder.     

Sonoluminescence：an IRaser creating cold fusion neutrons？

Sonluminescence can be explained by treating the bubbles as IRasers with standing waves in resonance with the bubble dimensions.Since the IRaser resonant radiation is required to satisfy wave boundary conditions,the water molecules lining the bubble walls undergo a continuous population inversion conditions,the water molecules lining the bubble walls undergo a continuous population inversion as the bubble collapses.By stimulated processes,the Planck energy accumulates as the KbT energy of radiation photons is pumped from the surroundings through the rotational state of the water molecule.Bubble collapse occurs almost isothermally with the high IR absorptivity of the water molecule permitting the Planck energy to accumulate to 2-6eV only to be released by VIS-UV photon emission because of the low absorptivity of water at VIS-UV frequencies.As the IRaser cavity dimensions collapse to the spacing between water molecules at liquid density,soft X-rays at about 2keV are predicted.But,this is less than 10keV necessary for cold fusion so that no neutrons is directly expected yet.Therefore,it is suggested that UV laser enhancement is used to accumulate further bubble collapse energy.     

Soft errors in floating gate memory cells: A review

Soft errors due to neutrons and alpha particles are among the main threats for the reliability of digital circuits operating at terrestrial level. These kinds of errors are typically associated with SRAMs and latches or DRAMs, and less frequently with non-volatile memories. In this paper we review the studies on the response of NAND and NOR Flash memories to ionizing particles, focusing on both single-level and multi-level cell architectures, manufactured in technologies down to a feature size of 25 nm. We discuss experimental error rates obtained with accelerated tests and identify the relative importance of neutron and alpha contributions. Technology scaling trends are finally discussed and modelled.     

Measurements of activation cross sections for Lu(n, α)Tm,Lu(n, α)Tm and Lu(n, p)Yb reactions induced by neutrons around 14 MeV

The cross sections for the ¹⁷⁵Lu(n, α)¹⁷²Tm, ¹⁷⁶Lu(n, α)¹⁷³Tm and ¹⁷⁵Lu(n, p)^175m+gYb reactions have been measured in the neutron energy range of 13.5–14.8 MeV using the activation technique. The first data for ¹⁷⁵Lu(n, α)¹⁷²Tm reaction cross sections are presented. In our experiment, the fast neutrons were produced via the ³H(d, n)⁴He reaction on K-400 Neutron Generator at Chinese Academy of Engineering Physics (CAEP). Induced gamma activities were measured by a high-resolution (1.69 keV at 1332 keV for ⁶⁰Co) gamma-ray spectrometer with high-purity germanium (HPGe) detector. Measurements were corrected for gamma-ray attenuations, random coincidence (pile-up), dead time and fluctuation of neutron flux. The neutron fluences were determined by the cross section of ⁹³Nb(n, 2n)^92mNb or ²⁷Al(n, α)²⁴Na reactions. The neutron energy in the measurement was by the cross section ratios of ⁹⁰Zr(n, 2n)^89m+gZr and ⁹³Nb(n, 2n)^92mNb reactions. The results were discussed and compared with experimental data found in the literature and with results of published empirical formulae.     

Development of the high-energy neutron fluence rate standard field in Japan with a peak energy of 45 MeV using the 7Li(p,n)7Be reaction at TIARA

In this study, we developed a 45 MeV neutron fluence rate standard of Japan. Quasi-monoenergetic neutrons with a peak energy of 45 MeV in the neutron standard field were produced by the ⁷Li(p,n)⁷Be reaction using a 50-MeV proton beam from an azimuthally varying field (AVF) cyclotron of the Takasaki Ion Accelerators for Advanced Radiation Application (TIARA). The neutron energy spectrum was measured using an organic liquid scintillation detector and a ⁶Li-glass scintillation detector by the time-of-flight method, and using a Bonner sphere spectrometer by the unfolding method. The absolute neutron fluence was determined using a proton recoil telescope (PRT) composed of the liquid scintillation detector and a Si(Li) detector that was newly developed in the present study. The detection efficiency of the PRT was obtained using the MCNPX code. The peak neutron production cross section for the ⁷Li(p,n)⁷Be reaction was also derived from the neutron fluence in order to confirm the neutron fluence of the TIARA high-energy neutron field. The peak neutron production cross section obtained in the present study was in good agreement with those of previous studies. The characteristics of the 45-MeV neutron field in TIARA were successfully evaluated in order to calibrate high-energy neutron detectors and high-energy neutron dosimeters.     

The total cross sections of the ~(11)B(α,n)~(14N) and the ~(10)B(α,n)~(13)N reactions between 2 and 6 MeV

There is considerable interest in potential aneutronic fusion reactors. One possible reaction is~(11)B(p,a)2a.However, the emitted alpha particles are energetic enough to generate neutrons by interacting with boron inside the reactor through the ~(11)B(α,n)~(14N) and ~(10)B(α,n)~(13)N reactions.To aid in evaluating neutron production within this potential aneutronic reactor, the total cross sections were measured for the ~(11)B(α,n)~(14N) reaction between 2 and 6 MeV and for the ~(10)B(α,n)~(13)N reaction between 2 and 4.8 MeV. The results are presented and compared with previously reported results.     

The detection and sizing of flaws in components from the hot-end of gas turbines using phase-contrast radiography with neutrons: a feasibility study

In this paper we present a feasibility study of the use of phase contrast radiography in the examination of components from the hot-section of gas turbine engines. These components are usually made from dense materials (nickel or cobalt based superalloys) and, consequently, radiographic examination requires either high energy X-rays (above 60 keV) or neutrons. The relative merits of employing X-rays and neutrons for phase contrast radiography are compared. It is shown that, for similar penetration, neutrons offer better sensitivity and that it should be possible to detect even micron-wide cracks orientated perpendicular to the incident rays. Simulation shows that, for cracks parallel to the incident rays, crack growth in increments of microns can be resolved by monitoring the development of the Fresnel diffraction pattern. Some preliminary experimental results are also presented that demonstrate an improvement over conventional neutron radiography.