The GAPS experiment to search for dark matter using low-energy antimatter

© Copyright owned by the author(s) under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives 4.0 International License (CC BY-NC-ND 4.0). The GAPS experiment is designed to carry out a sensitive dark matter search by measuring low-energy cosmic ray antideuterons and antiprotons. GAPS will provide a new avenue to access a wide range of dark matter models and masses that is complementary to direct detection techniques, collider experiments and other indirect detection techniques. Well-motivated theories beyond the Standard Model contain viable dark matter candidates which could lead to a detectable signal of antideuterons resulting from the annihilation or decay of dark matter particles. The dark matter contribution to the antideuteron flux is believed to be especially large at low energies (E < 1 GeV), where the predicted flux from conventional astrophysical sources (i.e. from secondary interactions of cosmic rays) is very low. The GAPS low-energy antiproton search will provide stringent constraints on less than 10 GeV dark matter, will provide the best limits on primordial black hole evaporation on Galactic length scales, and will explore new discovery space in cosmic ray physics. Unlike other antimatter search experiments such as BESS and AMS that use magnetic spectrometers, GAPS detects antideuterons and antiprotons using an exotic atom technique. This technique, and its unique event topology, will give GAPS a nearly background-free detection capability that is critical in a rare-event search. GAPS is designed to carry out its science program using long-duration balloon flights in Antarctica. A prototype instrument was successfully flown from Taiki, Japan in 2012. GAPS has now been approved by NASA to proceed towards the full science instrument, with the possibility of a first long-duration balloon flight in late 2020. This presentation will motivate low-energy cosmic ray antimatter searches and it will discuss the current status of the GAPS experiment and the design of the payload

Boron And Carbon Cosmic rays in the Upper Stratosphere (BACCUS)

International audienceThe balloon-borne BACCUS experiment measures directly the elemental spectra of cosmic-ray nuclei from protons to Fe over the energy range ~10^12 to 10^15 eV. It focuses on the energy dependence of secondary to primary ratios (e.g. B/C) to investigate cosmic-ray propagation history. BACCUS consists of redundant and complementary particle detectors including the Timing Charge Detector (TCD), Transition Radiation Detector (TRD), Cherenkov Detector (CD), Silicon Charge Detector (SCD), and Calorimeter (CAL). The TCD measures the light yield produced by the particle in plastic scintillator. The TRD provides energy measurements of incident 3 ≤ Z ≤ 26 nuclei in the 102 – 105 Lorentz factor range. The CD responds only to particles with velocity exceeding the velocity of light in the plastic. It allows BACCUS to reject the abundant low energy cosmic rays present in the polar region. The CAL is used to determine the particle’s energy for all nuclei for 1 ≤ Z ≤ 26. With the SCD based on pixellation, in addition to the TCD based on timing, and the CD, the BACCUS instrument implements virtually all possible techniques to minimize the effect of backscatter on charge measurements in the presence of a large particle shower in the CAL. The 30 day flight was carried out successfully over Antarctica in 2016 from Nov. 28 to Dec. 28. The integration test, and performance of instruments will be presented