Sensitivities of Future Long Baseline Experiments in the US

Sensitivities to neutrino oscillation parameters for possible very long baseline neutrino oscillation experiments are discussed. The reach for observing a non-zero mixing angle $\theta_{13}$, establishing CP violation and determining the mass hierarchy are compared between various experimental options. Different possibilities for neutrino beams are briefly described, as well as the assumptions about the performance of a large water Cherenkov and liquid Argon detector.Comment: To appear in the proceedings of the 9th International Workshop On Neutrino Factories, Superbeams and Betabeams (NuFact07) August 6-11, 2007, Okayama University, Japa

Cosmic radiation exposure of aviators for solar cycles 23 and 24

Assessing the radiation exposure of aviators and frequent flyers requires the study of the cosmic ray showers inside the Earth’s atmosphere. DYASTIMA / DYASTIMA-R is a Geant4 based software application, implemented by the Athens Cosmic Ray Group which allows the study of the evolving secondary particles cascades inside the atmosphere, as well as radiation dosimetry calculations (ambient dose equivalent rate) at different atmosphe - ric altitudes, geographic coordinates and magnetic cut-off rigidity. Results for various scenarios, as calculated by DYASTIMA/DYASTIMA-R, are provided as a federated product through the European Space Agency Space Situational Awareness of the Space Radiation Service Centre Network, while the DYASTIMA software is provi- ded through the Athens Neutron Monitor Station (A.Ne.Mo.S.) portal. Initial results for the assessment of the radiation exposure during the last Solar Cycles 23 and 24 are presented in this work, covering the most usual flying altitudes. The results indicate the dependence of the dose rate on the magnetic cut-off rigidity threshold, with higher dose rates at high geographic latitudes, as well as the anti-correlation of cosmic ray intensity with the solar activity, as higher dose rates are observed during solar minimum conditions

Catalogue of 55-80 MeV solar proton events extending through solar cycles 23 and 24

We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the SOHO/ERNE experiment. In addition to ERNE proton and heavy ion observations, data from the ACE/EPAM (near-relativistic electrons), SOHO/EPHIN (relativistic electrons), SOHO/LASCO (coronal mass ejections, CMEs), and GOES soft X-ray experiments are also considered and the associations between the particle and CME/X-ray events deduced to obtain a better understanding of each event. A total of 176 SEP events have been identified as having occurred during the time period of interest; their onset and solar release times have been estimated using both velocity dispersion analysis (VDA) and time-shifting analysis (TSA) for protons, as well as TSA for near-relativistic electrons. Additionally, a brief statistical analysis has been performed on the VDA and TSA results, as well as the X-rays and CMEs associated with the proton/electron events, both to test the viability of the VDA and to investigate possible differences between the two solar cycles. We find, in confirmation of a number of previous studies, that VDA results for protons that yield an apparent path length of 1 AU < s <~ 3 AU seem to be useful, but those outside this range are probably unreliable, as evidenced by the anticorrelation between apparent path length and release time estimated from the X-ray activity. It also appears that even the first-arriving energetic protons apparently undergo significant pitch angle scattering in the interplanetary medium, with the resulting apparent path length being on average about twice the length of the spiral magnetic field. The analysis indicates an increase in high-energy SEP events originating from the far eastern solar hemisphere; e.g., such an event...Comment: 33 pages, 12 figures (2 with multiple image files), 1 appendix as an external PDF file. Article is in the accepted manuscript/referee (single column) forma

Atmospheric cosmic ray induced ionization and radiation affecting aviation

Cosmic radiation is a major factor of ionization of the Earth’s atmosphere. Both solar and galactic cosmic rays, which depend on solar activity and geomagnetic field, affect the radiation exposure in the atmosphere. Several models have been created for the estimation of the ionization and radiation dosimetry. In this work, as regards the ionization rate computations the CRAC:CRII model by the University of Oulu (https://cosmicrays.oulu.fi/CRII/CRII.html) was used, while for the estimation of the ambient equivalent dose rate (dH*(10)/dt) we used the validated software DYASTIMA / DYASTIMA-R by the University of Athens (http://cosray.phys.uoa.gr/index.php/applications/dyastima). Both tools are of great importance as they allow us to calculate the respective quantities all over the globe, at the entire atmosphere and for different time periods and solar cycle phases. The study concerns the last two solar cycles 23 and 24 (1996–2019) and specific flight levels of commercial aviation (FL310, FL350 and FL390). The dependance of CRII and dH*(10)/dt on geomagnetic cut-off rigidity, solar activity, cosmic ray intensity, as well as the altitude inside the atmosphere, affect the radiation exposure of the air crew members and frequent flyers, which make the results very interesting for the aviation industr

The updated GLE alert system by ANEMOS

Ground level enhancements (GLEs) of cosmic radiation are the result of solar energetic particles (SEPs) arriving at the Earth, potentially causing major damage to technological systems, but also posing a threat for human health. Intense SEPs, such as the GLE events, can influence the radiation exposure of aircrafts and consequently increase the radiation dose on human crew, but also have an impact on satellites and affect the design of space missions, i.e electronic devices onboard the satellite platforms etc. Therefore, predicting such events is challenging and one of the most important aspects of space weather research. In this work the updated GLE Alert++ System of the Athens Neutron Monitor Station (A.Ne.Mo.S.) implemented by the Athens Cosmic Ray Group of the National and Kapodistrian University of Athens (NKUA) is being presented. Moreover, the innovations of the updated system in relation to the previous version of the GLE Alert Plus are introduced. Finally, the most recent and the first of solar cycle 25 GLE event, GLE73, is discussed. This event was registered by several stations of the worldwide ground-based neutron monitor network. An accurate alert was issued successfully by the ESA R-ESC federated product GLE Alert Plus, as well as by the updated GLE Alert++ System of the NKUA/A.Ne.Mo.S. It should be emphasized that GLE Alert++ signal by NKUA/A.Ne.Mo.S. was issued 45 minutes earlier than the one issued by GOES satellites

Prediction of solar proton event fluence spectra from their peak flux spectra

Solar Proton Events (SPEs) are of great importance and significance for the study of Space Weather and Heliophysics. These populations of protons are accelerated at high energies ranging from a few MeVs to hundreds of MeVs and can pose a significant hazard both to equipment on board spacecrafts as well as astronauts as they are ionizing radiation. The ongoing study of SPEs can help to understand their characteristics, relative underlying physical mechanisms, and help in the design of forecasting and nowcasting systems which provide warnings and predictions. In this work, we present a study on the relationships between the Peak Flux and Fluence spectra of SPEs. This study builds upon existing work and provides further insights into the characteristics and the relationships of SPE Peak flux and Fluence spectra. Moreover it is shown how these relationships can be quantified in a sound manner and exploited in a simple methodology with which the Fluence spectrum of an SPE can be well predicted from its given Peak spectrum across two orders of magnitude of proton energies, from 5 MeV to 200 MeV. Finally it is discussed how the methodology in this work can be easily applied to forecasting and nowcasting systems

The probabilistic solar particle event forecasting (PROSPER) model

The Probabilistic Solar Particle Event foRecasting (PROSPER) model predicts the probability of occurrence and the expected peak flux of solar energetic particle (SEP) events. Predictions are derived for a set of integral proton energies (i.e., E > 10, > 30, and > 100 MeV) from characteristics of solar flares (longitude, magnitude), coronal mass ejections (width, speed), and combinations of both. Herein the PROSPER model methodology for deriving the SEP event forecasts is described, and the validation of the model, based on archived data, is presented for a set of case studies. The PROSPER model has been incorporated into the new operational advanced solar particle event casting system (ASPECS) tool to provide nowcasting (short term forecasting) of SEP events as part of ESA's future SEP advanced warning system (SAWS). ASPECS also provides the capability to interrogate PROSPER for historical cases via a run-on-demand functionality

Two solar proton fluence models based on ground level enhancement observations

Solar energetic particles (SEPs) constitute an important component of the radiation environment in interplanetary space. Accurate modeling of SEP events is crucial for the mitigation of radiation hazards in spacecraft design. In this study we present two new statistical models of high energy solar proton fluences based on ground level enhancement (GLE) observations during solar cycles 19–24. As the basis of our modeling, we utilize a four parameter double power law function (known as the Band function) fits to integral GLE fluence spectra in rigidity. In the first model, the integral and differential fluences for protons with energies between 10 MeV and 1 GeV are calculated using the fits, and the distributions of the fluences at certain energies are modeled with an exponentially cut-off power law function. In the second model, we use a more advanced methodology: by investigating the distributions and relationships of the spectral fit parameters we find that they can be modeled as two independent and two dependent variables. Therefore, instead of modeling the fluences separately at different energies, we can model the shape of the fluence spectrum. We present examples of modeling results and show that the two methodologies agree well except for a short mission duration (1 year) at low confidence level. We also show that there is a reasonable agreement between our models and three well-known solar proton models (JPL, ESP and SEPEM), despite the differences in both the modeling methodologies and the data used to construct the models.</p

Very high energy proton peak flux model

Solar energetic particles (SEPs) pose a serious radiation hazard to spacecraft and astronauts. The highest energy SEPs are a significant threat even in heavily shielded applications. We present a new probabilistic model of very high energy differential peak proton fluxes. The model is based on GOES/HEPAD observations between 1986 and 2018, i.e., covering very nearly three complete solar cycles. The SEP event list for the model was defined using a statistical criterion derived by setting the possibility of false detection of an event to 1%. The peak flux distributions were calculated for the interpolated energies 405 MeV, 500 MeV and 620 MeV, and modelled with exponentially cut off power law functions. The HEPAD data were cleaned and corrected using a "bow-tie" method which is based on the response functions of the HEPAD channels P8-P10 found in the instrument calibration reports. The results of the model are available to the Space Weather community as a web-based tool at the ESA's Space Situational Awareness Programme Space Weather Service Network