| Welcome to EXPACS homepage! EXPACS represents "EXcel-based Program for calculating Atmospheric Cosmic-ray Spectrum". It can instantaneously calculate terrestrial cosmic ray fluxes of neutrons, protons, ions with charge up to 28 (Ni), muons, electrons, positrons, and photons nearly anytime and anywhere in the Earth's atmosphere. Based on the calculated cosmic-ray fluxes, EXPACS can also deduce the effective dose, ambient dose equivalent, and absorbed dose in air due to cosmic-ray exposure. The calculated cosmic-ray dose rates can be visualized on the map of Google EarthTM using EXPACS-V, which can be also downloaded from this web site. If you have any questions or comments on these programs, please E-mail to nsed-expacs  jaea.go.jp |
 Dec 3, 2024 EXPACS ver 4.16 was released. The accuracy in calculating proton fluxes at low altitudes (d > 300 g/cm2) has been improved. Nov 11, 2024 EXPACS ver 4.15 was released. The solar modulation data are updated up to Oct 31, 2024. The angular distribution of ground-level muon fluxes for cos(theta) above 0.5 has been slightly revised. Mar 24, 2024 EXPACS ver 4.14 was released. The solar modulation data are updated up to Mar 21, 2024. Jul 23, 2023 Source generation mode of PARMA (main-generation.*) was revised to consider the production of annihilation gamma-rays for both Fortran and C++ versions.. May 5, 2023 EXPACS ver 4.13 was released. The solar modulation data are updated up to May 3, 2023. Jun 17, 2022 EXPACS ver 4.12 was released. The solar modulation data are updated up to May 31, 2022. Jan 25, 2022 EXPACS ver 4.11 was released. The solar modulation data are updated up to Jan 24, 2022. Apr 07, 2021 EXPACS ver 4.10 was released. The solar modulation data are updated up to Mar 21, 2021. Sep 29, 2020 EXPACS ver 4.09 was released. The solar modulation data are updated up to Sep 28, 2020. A bug in main-generator.cpp was fixed. May 25, 2020 EXPACS ver 4.08 was released. The solar modulation data are updated up to May 25, 2020. C++ version of EXPACS (PARMA model itself) was also released Jan 14, 2020 EXPACS ver 4.07 was released. The solar modulation data are updated up to Jan 10, 2020. May 28, 2019 EXPACS ver 4.06 was released. The solar modulation data are updated up to May 27, 2019. PARMA4PHITS was improved to be capable of changing the calculation conditions without re-compiling PHITS. Dec 21, 2018 EXPACS ver 4.05 was released. The past solar modulation data are revised using 13 selected neutron monitors. Due to this revision, the calculated fluxes are slightly changed from the previous versions. The solar modulation data are updated up to Dec 19, 2018. EXPACS-V is also updated. May 15, 2018 EXPACS ver 4.04 was released. The solar modulation data are updated up to May 14, 2018. Jan 17, 2018 EXPACS-V ver. 2.0.0 was released. The new version can be executed on latest Windows machines. The database in the software was updated by calculating the dose rates using EXPACS 4.0. Jan 5, 2018 EXPACS ver 4.03 was released. The solar modulation data are updated up to Jan 4, 2018. Jul 26, 2017 EXPACS ver 4.02 was released. The solar modulation data are updated up to July 25, 2017. A bug that muon fluxes at high cut-off rigidity regions became #VALUE is fixed. March 8, 2017 EXPACS ver 4.01 was released. The solar modulation data are updated up to March 8, 2017. Function to consider the latitude depdence for converting from altitude to atmospheric depth is implemented. Source generation program for Particle and Heavy Ion Transport code System PHITS based on PARMA is also released (see download -> PARMA4PHITS.zip). Aug 5, 2016 Paper for describing the detail of PARMA/EXPACS 4.0 is published in PLOS ONE. It is an open access article, and you can download it from here. July 22, 2016 EXPACS ver. 4.00 was released. In the new version, not only omni-directional but also angular differential fluxes of terrestrial cosmic rays can be calculated. A FORTRAN program of cosmic ray generator, which determines energy and direction of each terrestrial cosmic ray at a certain condition using random number, is also released. July 21, 2016 EXPACS ver 3.03 was released. The solar modulation data are updated up to July 20, 2016. May 11, 2016 EXPACS ver 3.02 was released. Conversion coefficients from fluence to absorbed dose in air were revised. The solar modulation data are updated up to May. 11, 2016. Jan 6, 2016 EXPACS ver 3.01 was released. Parameters used for muon flux calculation were slightly revised. The solar modulation data are updated up to Dec. 31, 2015. Jan 2, 2016 FORTRAN version of EXPACS is revised to be compatible to Linux. Dec 16, 2015 Paper for describing the detail of PARMA/EXPACS 3.0 is published in PLOS ONE. It is an open access article, and you can download it from here. Nov 30, 2015 EXPACS ver. 3.00 was released. In the new version, all parameters used in the analytical functions were revised based on the results of the airshower simulation performed by a new version of PHITS. The important features of the new version in comparison to the previous version are:
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