High-Energy Particles in the Heliosphere

This project has received funding from the European Union’s Horizon Europe programme under grant agreement No 101135044 Special course (High-Energy Particles in the Heliosphere): Measurement of ions 2025-05-16 special course Bernd Heber, Christian-Albrechts-University to Kiel Disclaimer 2 •… 2025-05-16 Special course Motivation 01 Goals and Objectives 32025-05-16 Special course Adapted from Bishoff & Potgieter (2016) 10.1007/s10509-015-2633-8 The E6 Instrument aboard Helios 42025-05-16 Special course •Sketch of the E6 Sensor •5 Semiconductor detectors •Anticoincidence cylinder. •Cherenkov detector made out of Saphire •Instrument utilizes the dE/dx-E-method and the dE/dx-Cherencov-method From Marquardt and Heber (2019) https://doi.org/10.1051/0004 -6361/201935413 The E6 Instrument aboard Helios 2025-05-16 Special course 5 From Marquardt and Heber (2019) https://doi.org/10.1051/0004 -6361/201935413 Marquardt et al. (2018) https://doi.org/10.1051/0004 - 6361/201731490 What happens at higher energies when particles penetrate the sensor? 62025-05-16 Special course Beyond a certain energy – for the Electron Proton Helium INstrument 50 MeV/n - particles penetrate the sensor. The resulting distribution is shown on the left. How to derive energy spectra from such measurements? The energy loss vs energy loss method 02 72025-05-16 Special course Principle of the (∆E −∆E) method 82025-05-16 Special course •When a charged particle passes through a material, it loses energy due to interactions with the material (ionization) described by the Bethe-Bloch equation: •The particle passes through two detectors: •a thin SSD (ΔE ~dE/dx|E) and •a thicker one (ΔE ~dE/dx|E’) Application of the (∆E −∆E) method utilizing a SSD telescope 92025-05-16 Special course Three regimes are found •Particles stopping ΔE in D2 increases with energy. •Penetration point particle starts to penetrate D2 but ΔΕ/Δx in D2 larger than in D1 •ΔΕ/Δx in D2 equals ΔΕ/Δx in D1 Example of the (∆E −∆E) method utilizing the Helios E6 2025-05-16 Special course 16 ☺looks exactly as expected But: 1. How to know the energy ranges? 2. How to know the efficiency? Set up an appropriate Monte Carlo simulation From Marquardt and Heber (2019) https://doi.org/10.1051/0004 -6361/201935413 A simple model 04 All Tasks Description as per DoA 172025-05-16 Special course The simple approach (stopping particles) 2025-05-16 Special course 18 The simple approach (penetrating particles) 2025-05-16 Special course 19 •Use the energy loss points computed via Bethe-Bloch to define an energy loss range. •Take the corresponding energies •Thus, the energy range is given The simple approach (penetrating particles) 2025-05-16 Special course 20 ~110 MeV ~225 MeV 12/9/2025 Interaction of particles with matter 21 The Gathering Power is computed by MC methods For an ideal telescope: •efficiency for detecting particles of a given type is one in a given energy interval and zero otherwise •Detectors are mathematical surfaces with no thickness The factor of C(E) = G(E) * Φ(E) relating the count rate C to the flux Φis defined as the gathering power G of the telescope that can be computed from MC computation as: G(E) = (number of trajectories detected / total number of trajectories chosen) ×π A miss A sophisticated model: GEANT 4 computations 05 All Tasks Description as per DoA 222025-05-16 Special course The GEANT 4 model 2025-05-16 Special course 23 The recommended setup requires three resources: 1.A Virtualization Software (VMware Workstation Player 17) for Windows or VMWare Fusion for Mac 2.A Geant4 Virtual Machine 3.The GEANT 4 application source code Bethe Bloch versus GEANT 4 2025-05-16 Special course 24 The GEANT 4 model 2025-05-16 Special course 25 •GEANT simulations lead to no box-car distributions •Response has long tails • Overlap of particles … •Why •What to change? From Marquardt and Heber (2019) https://doi.org/10.1051/0004 -6361/201935413 •dE/dx –dE/dxmethod allows extension to energies to about 600 MeV •dE/dx –Cherencov method allows much better particle separation and directionality. I.e. Important if spacecraft behind the instrument. •Threshold detector allows to measure up to the MIP above 1 GeV. •Breaks the Gap between standard spacecraft instruments and neutron monitors at Earth. Summary: 2025-05-16 Special course 32 From Marquardt and Heber (2019) https://doi.org/10.1051/0004 -6361/201935413 This project has received funding from the European Union’s Horizon Europe programme under grant agreement No 101135044 www.spearhead-he.eu [email protected] Thank you for your attention! 33 This project has received funding from the European Union’s Horizon Europe programme under grant agreement No 101135044 www.spearhead-he.eu [email protected] References 34 1. Marquardt, J., Heber, B., Potgieter, M. S., & Strauss, R. D. (2018). Energy spectra of carbon and oxygen with HELIOS E6 –Radial gradients of anomalous cosmic ray oxygen within 1 AU. Astronomy & Astrophysics, 610, A42. https://doi.org/10.1051/0004-6361/201731490 2. Marquardt, J. & Heber, B. (2019). Galactic cosmic ray hydrogen spectra and radial gradients in the inner heliosphere measured by the HELIOS Experiment 6. Astronomy & Astrophysics, 625, A153. https://doi.org/10.1051/0004-6361/201935413 3. Bisschoff, D. & Potgieter, M. S. (2016). New local interstellar spectra for protons, helium and carbon derived from PAMELA and Voyager data. Astrophysics and Space Science, 361, 48. https://doi.org/10.1007/s10509-015-2633-8