SuperTIGER (Super Trans-Iron Galactic Element Recorder) is a balloon-borne instrument designed to directly measure ultra-heavy Galactic cosmic-ray (UHGCR) nuclei. SuperTIGER had two successful Antarctic flights: SuperTIGER-1 in 2012 for 55 days, and SuperTIGER-2 in 2019 for 32 days. Stratospheric float altitudes varied between ∼ 36 – 40 km for the flights. To obtain top-of-atmosphere (TOA) abundances, the observed abundance measurements must be corrected for propagation through the residual ∼ 0.5% of atmosphere and inactive detector material. The approach developed for the previous TIGER instrument propagates TOA elemental abundances from satellite measurements down through the atmosphere to flight altitudes, accounting for gains and losses due to charge-changing nuclear interactions. Final TOA abundances are found by iteratively adjusting the assumed TOA abundances in the propagation model until the model produces instrument abundances that match the flight measurements. We develop a new method to obtain TOA abundances of UHGCR nuclei by simulating nuclear interactions and energy losses cosmic-ray nuclei experience propagating through the atmosphere using Geant4. We simulate a slab of atmosphere material as well as instrument material above the active detector and record energy loss and nuclear interactions of Galactic cosmic ray (GCR) projectiles. Results from these simulations are used to create a response matrix to describe the charge-changing losses or gains of cosmic-ray nuclei species. The simulation results are also used to obtain required TOA energy for cosmic-ray nuclei to trigger SuperTIGER's acrylic Cherenkov detector (320 MeV/nuc). We compare the TOA energy and TOA abundances from simulation-based corrections to previous analytical corrections.
",
"doi": "10.1016/j.asr.2025.10.040",
"issn": "0273-1177",
"publisher": "Elsevier",
"publication": "Advances in Space Research",
"publication_date": "2026-04-15",
"series_number": "8",
"volume": "77",
"issue": "8",
"pages": "8323-8336"
},
{
"id": "authors:83x05-bhq33",
"collection": "authors",
"collection_id": "83x05-bhq33",
"cite_using_url": "https://authors.library.caltech.edu/records/83x05-bhq33",
"type": "article",
"title": "IS\u2299IS Solar \u03b3-Ray Measurements: Initial Observations and Calibrations",
"author": [
{
"family_name": "Mitchell",
"given_name": "J. G.",
"orcid": "0000-0003-4501-5452",
"clpid": "Mitchell-John-Grant"
},
{
"family_name": "de Nolfo",
"given_name": "G. A.",
"orcid": "0000-0002-3677-074X",
"clpid": "de-Nolfo-Georgia-A"
},
{
"family_name": "Christian",
"given_name": "E. R.",
"orcid": "0000-0003-2134-3937",
"clpid": "Christian-Eric-R"
},
{
"family_name": "Leske",
"given_name": "R. A.",
"orcid": "0000-0002-0156-2414",
"clpid": "Leske-Richard-A"
},
{
"family_name": "Ryan",
"given_name": "J. M.",
"orcid": "0000-0003-3534-5968"
},
{
"family_name": "Vievering",
"given_name": "J. T.",
"orcid": "0000-0002-7407-6740",
"clpid": "Vievering-Juliana-T"
},
{
"family_name": "Hill",
"given_name": "M. E.",
"orcid": "0000-0002-5674-4936",
"clpid": "Hill-Matthew-E"
},
{
"family_name": "Labrador",
"given_name": "A. W.",
"orcid": "0000-0001-9178-5349",
"clpid": "Labrador-Allan-W"
},
{
"family_name": "Wiedenbeck",
"given_name": "M. E.",
"orcid": "0000-0002-2825-3128",
"clpid": "Wiedenbeck-Mark-E"
},
{
"family_name": "McComas",
"given_name": "D. J.",
"orcid": "0000-0001-6160-1158",
"clpid": "McComas-David-J"
},
{
"family_name": "Cohen",
"given_name": "C. M. S.",
"orcid": "0000-0002-0978-8127",
"clpid": "Cohen-Christina-M-S"
},
{
"family_name": "McNutt",
"given_name": "R. L.",
"orcid": "0000-0002-4722-9166",
"clpid": "McNutt-Ralph-L"
},
{
"family_name": "Mewaldt",
"given_name": "R. A.",
"orcid": "0000-0003-2178-9111",
"clpid": "Mewaldt-R-A"
},
{
"family_name": "Mitchell",
"given_name": "D. G.",
"orcid": "0000-0003-1960-2119",
"clpid": "Mitchell-Donald-G"
},
{
"family_name": "Rankin",
"given_name": "J. S.",
"orcid": "0000-0002-8111-1444",
"clpid": "Rankin-Jamie-S"
},
{
"family_name": "Schwadron",
"given_name": "N. A.",
"orcid": "0000-0002-3737-9283",
"clpid": "Schwadron-Nathan-A"
}
],
"abstract": "\n
High-energy neutral solar radiation in the form of γ-rays and neutrons is produced as secondary products in solar flares. The characteristics of this emission can provide key information regarding the energization of charged particles, particularly when primary particles remain trapped in the corona. The Integrated Science Investigation of the Sun (IS\u2299IS) suite on Parker Solar Probe is composed of instruments primarily intended to measure energetic charged particles. However, the High Energy Telescope (HET) in IS\u2299IS was also designed with a supplementary neutral mode intended to measure γ-rays and neutrons. HET observed its first clear solar γ-ray event in connection with a hard X-ray flare, the eruption of a coronal mass ejection, and a solar energetic particle event on 2022 September 5. The X-ray spectral shape was observed to harden over the course of the event, culminating with the observation of γ-rays by HET. A coincident enhancement in the lower-energy Energetic Particle Instrument (EPI-Lo) was also observed, likely produced by incident solar γ-rays despite the EPI-Lo instrument not having any special neutral measurement capabilities. We use Monte Carlo modeling to reconstruct the incident γ-ray spectrum based on the measured spectrum to demonstrate that the combination of IS\u2299IS instruments can measure hard X-rays and γ-rays from ∼60 keV–7 MeV. Despite the fact that this is a supplemental science goal of the mission, the capability of the IS\u2299IS instruments to measure γ-rays is important for the study of this population due to the very limited instruments currently observing the Sun in γ-rays.
\n
\n
On 2022 September 5, Parker Solar Probe (Parker) observed a large solar energetic particle (SEP) event at the unprecedented distance of only 15 RS from the Sun. The observations from the Integrated Science Investigation of the Sun (IS\u2299IS) obtained over the course of this event are remarkably rich, and an overview is presented here. IS\u2299IS is capable of measuring ions from 20 keV to over 100 MeV nuc−1 and electrons from 30 keV to 6 MeV; here, we primarily focus on the proton and helium measurements above 80 keV. Among the surprising results are evidence of inverse velocity dispersion at energies above 1 MeV during the onset of the event, a sharp decrease in the energetic particle intensities at all energies at the interplanetary shock crossing, and repeated short durations of highly anisotropic sunward flow. Many changes in the SEP intensities, anisotropy, and spectral steepness are coincident with solar wind structure boundaries identified using the Parker solar wind magnetic field and plasma data. However, there are significant changes that are not correlated with any clearly visible solar wind variation. The observations presented here serve as an introduction to a complex event with numerous opportunities for future, more in-depth studies.
\n