Neutron monitors and muon detectors for solar modulation studies: Interstellar flux, yield function, and assessment of critical parameters in count rate calculations

Particles count rates at given Earth location and altitude result from the convolution of (i) the interstellar (IS) cosmic-ray fluxes outside the solar cavity, (ii) the time-dependent modulation of IS into Top-of-Atmosphere (TOA) fluxes, (iii) the rigidity cut-off (or geomagnetic transmission function) and grammage at the counter location, (iv) the atmosphere response to incoming TOA cosmic rays (shower development), and (v) the counter response to the various particles/energies in the shower. Count rates from neutron monitors or muon counters are therefore a proxy to solar activity. In this paper, we review all ingredients, discuss how their uncertainties impact count rate calculations, and how they translate into variation/uncertainties on the level of solar modulation $\varphi$ (in the simple Force-Field approximation). The main uncertainty for neutron monitors is related to the yield function. However, many other effects have a significant impact, at the 5-10\% level on $\varphi$ values. We find no clear ranking of the dominant effects, as some depend on the station position and/or the weather and/or the season. An abacus to translate any variation of count rates (for neutron and $\mu$ detectors) to a variation of the solar modulation $\varphi$ is provided.Comment: 28 pages, 16 figures, 9 tables, match accepted version in AdSR (minor corrections, Dorman (1974,2004,2009) reference textbooks added

Neutron monitors and muon detectors for solar modulation studies: 2. ϕ\phi time series

The level of solar modulation at different times (related to the solar activity) is a central question of solar and galactic cosmic-ray physics. In the first paper of this series, we have established a correspondence between the uncertainties on ground-based detectors count rates and the parameter $\phi$ (modulation level in the force-field approximation) reconstructed from these count rates. In this second paper, we detail a procedure to obtain a reference $\phi$ time series from neutron monitor data. We show that we can have an unbiased and accurate $\phi$ reconstruction ($\Delta\phi/\phi\simeq 10\%$). We also discuss the potential of Bonner spheres spectrometers and muon detectors to provide $\phi$ time series. Two by-products of this calculation are updated $\phi$ values for the cosmic-ray database and a web interface to retrieve and plot $\phi$ from the 50's to today (\url{http://lpsc.in2p3.fr/crdb}).Comment: 15 pages, 5 figures, 2 tables. AdSR, in press. Web interface to get modulation parameter phi(t): new tab in http://lpsc.in2p3.fr/crd

Atmospheric radiation environment analyses based-on CCD camera, neutron spectrometer and multi-physics modeling

International audienceIn this paper, high-altitude measurements of both radiation environment and effects are described. Measurements are made using a neutron spectrometer and CCD camera. MUSCA SEP3 software is used to correlate both measurement approaches. Analyses of the charge levels in pixels induced by radiation events are proposed. Then, cross-comparison analyses based on a CCD camera and HERMEIS neutron spectrometer are performed to investigate radiation dynamic properties, including neutron/proton and muon contributions. © 2013 IEEE

MULTI-PHYSICS MODELLING CONTRIBUTIONS TO INVESTIGATE THE ATMOSPHERIC COSMIC RAYS ON THE SINGLE EVENT UPSET SENSITIVITY ALONG THE SCALING TREND OF CMOS TECHNOLOGIES

International audienceParticles originating from primary cosmic radiation, which hit the Earth's atmosphere give rise to a complex field of secondary particles. These particles include neutrons, protons, muons, pions, etc. Since the 1980s it has been known that terrestrial cosmic rays can penetrate the natural shielding of buildings, equipment and circuit package and induce soft errors in integrated circuits. Recently, research has shown that commercial static random access memories are now so small and sufficiently sensitive that single event upsets (SEUs) may be induced from the electronic stopping of a proton. With continued advancements in process size, this downward trend in sensitivity is expected to continue. Then, muon soft errors have been predicted for nano-electronics. This paper describes the effects in the specific cases such as neutron-, proton-and muon-induced SEU observed in complemen-tary metal-oxide semiconductor. The results will allow investigating the technology node sensitivity along the scaling trend

Characterization of the neutron environment at the CERN-EU High Energy Reference Field and at the Pic du Midi

International audienceA new platform dedicated to the long-term characterization of the Atmospheric Natural Radiative Environment at mountain altitude (Pic du Midi, +2885 m) is presented. The performance of a high energy neutron spectrometer is established by comparison with the neutron monitors

Characterization of the IRSN neutron multisphere spectrometer (HERMEIS) at European standard calibration fields

International audienceThe Institute for Radiological Protection and Nuclear Safety (IRSN) has developed a new spectrometry system for neutron energies from 10-9 MeV to 10 GeV. This high energy range multisphere extended IRSN system (HERMEIS) is a high gas pressure3He-based Bonner spheres set. It is adapted to low neutron fluence rate measurements and one of its main application concerns the determination of cosmic-ray-induced neutron spectra at ground level and mountain altitudes. The neutron fluence response matrix of the set of 13 Bonner spheres, including three extended ones with tungsten and lead shells, was calculated with the radiation transport code MCNPX-2.6f. Reliable fluence responses being mandatory for a correct evaluation of the atmospheric neutron spectra, HERMEIS was characterized at standard monoenergetic, quasi-monoenergetic and realistic neutron fields facilities. Measurements with monoenergetic neutron beams of 144 keV, 565 keV, 5 MeV and 17 MeV were performed at the NPL standard Van de Graaff facility. For the characterization of the response functions at higher energies, measurements were done at the Svedberg Laboratory, with 46 MeV and 144 MeV quasi-monoenergetic neutrons. Finally, to demonstrate the suitability of the system for broad cosmic-ray neutron spectra, measurements were performed at the TSL Atmospheric-like Neutrons from thIck TArget (ANITA) and also at the CERN European Realistic Field (CERF) facilities. Data from the realistic spectra were unfolded with the GRAVEL unfolding code and as a whole, a good agreement was found between the experimental and Monte-Carlo calculated neutron fluence energy distributions. © 2012 IOP Publishing Ltd and Sissa Medialab srl

Tomo-PTV with sparse tomographic reconstruction and optical flow

International audienceThe framework of this study is the conventional four cameras two time steps Tomo PIV. The rationale behind this paper, and its main contribution, is that using two ultra sparse tomographic reconstructions (one particle –one voxel: LocM-CoSaMP) at time step t and t+dt where the particles are only represented by the voxels they are embedded in, one can reliably link the particles in the two time steps and filter out most of the ghosts. It is acheived by driving the 3D particle matching by a measure of the 2D displacement on the images themselves (optical flow). To derive an accurate vector field, the positions of the matched particle are then refined by a global optimization to yield subvoxel location. The 3 steps of the proposed method are described. Synthetic experiments on a linear displacement and on a vortex ring are presented. The performances of Nearest Neighbors matching and optical flow matching are compared. The performances on the derived vector field are assed in terms root mean square error. We show on illustrations how well interpolating the vector field on a regular grid captures the structure of the flow

Accuracy assessment of a Lucas-Kanade based correlation method for 3D PIV

International audienceWe introduce and characterize a new 3D cross-correlation algorithm, which relies on gradient-based iterative volume deformation. The algorithm, FOLKI3D, is the extension to 3D PIV of the approach introduced by Champagnat et al. 2011. It has a highly parallel structure and is implemented on GPU. Additionally to the gradient approach for displacement estimation, we implemented a high-order interpolation scheme (with cubic B-Splines) in the volume deformation step, at a reasonable computational cost. Performance tests on synthetic volumic distributions first allow to characterize the spatial transfer function of the algorithm, and to confirm the efficiency of this interpolator, comparable to that of standard image deformation methods in planar PIV. A second series of synthetic tests then investigates the response of FOLKI3D to sources of noise specific to the tomographic PIV context, i.e. ghost particles. Depending on the tests, the algorithm is found as efficient or more robust than the state-of-the-art. The gain brought by the high-order interpolation is also confirmed in a situation with a large number of ghosts, and different reconstructed particle shapes

Characterization of the Neutron Environment and SEE Investigations at the CERN-EU High Energy Reference Field and at the Pic du Midi

International audienceA new platform dedicated to the long-term characterization of the Atmospheric Natural Radiative Environment at mountain altitude (Pic du Midi, +2885 m) is presented. The performance of a high energy neutron spectrometer is established with measurements performed in a realistic neutron field and by comparison with the neutron monitors. A SEE-rate prediction approach is also used on a 90 nm SRAM memory array which was irradiated at CERF and set up at the Pic du Midi during almost one year