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Cosmic-ray antideuterons could be a key for the discovery of exotic phenomena in our Galaxy, such as dark-matter annihilations or primordial black hole evaporation. Unfortunately the theoretical predictions of the antideuteron flux at Earth are plagued with uncertainties from the mechanism of antideuteron production and propagation in the Galaxy. We present the most up-to-date calculation of the antideuteron fluxes from cosmic-ray collisions with the interstellar medium and from exotic processes. We include for the first time the antideuteron inelastic interaction cross section recently measured by the ALICE collaboration to account for the loss of antideuterons during propagation. In order to bracket the uncertainty in the expected fluxes, we consider several state-of-the-art models of antideuteron production and of cosmic-ray propagation.

The search for exploitable deposits of water and other volatiles at the Moon’s poles has intensified considerably in recent years, due to the renewed strong interest in lunar exploration. With the return of humans to the lunar surface on the horizon, the use of locally available resources to support long-term and sustainable exploration programs, encompassing both robotic and crewed elements, has moved into focus of public and private actors alike. Our current knowledge about the distribution and concentration of water and other volatiles in the lunar rocks and regolith is, however, too limited to assess the feasibility and economic viability of resource-extraction efforts. On a more fundamental level, we currently lack sufficiently detailed data to fully understand the origins of lunar water and its migration to the polar regions. In this paper, we present LUVMI-X, a mission concept intended to address the shortage of in situ data on volatiles on the Moon that results from a recently concluded design study. Its central element is a compact rover equipped with complementary instrumentation capable of investigating both the surface and shallow subsurface of illuminated and shadowed areas at the lunar south pole. We describe the rover and instrument design, the mission’s operational concept, and a preliminary landing-site analysis. We also discuss how LUVMI-X fits into the diverse landscape of lunar missions under development.

Plastic scintillators are widely used in high-energy and medical physics, often for measuring the energy of ionizing radiation. Their main disadvantage is their non-linear response to highly ionizing radiation, called ionization quenching. This nonlinearity must be modeled and corrected for in applications where an accurate energy measurement is required. We present a new experimental technique to granularly measure the dependence of quenching on energy-deposition density. Based on this method, we determine the parameters for four commonly used quenching models for two commonly used plastic scintillators using protons with energies of 30 MeV to 100 MeV; and compare the models using a Bayesian approach. We also report the first model-independent measurement of the dependence of ionization quenching on energy-deposition density, providing a purely empirical view into quenching., Accepted manuscript

Cosmic antimatter is an excellent probe for many astrophysical processes. The abundancies and energy spectra of antiparticles help to understand the creation and propagation mechanisms of cosmic ray particles in the universe. The flux of geomagnetically trapped antiprotons in Earth’s inner radiation belt can help to verify our models of the production of secondary cosmic ray particles and their motion in Earth’s magnetic field. The Antiproton Flux in Space (AFIS) experiment will measure this flux using a novel CubeSat-sized particle detector. This active-target detector consists of 900 scintillating fibers read out by silicon photomultipliers and is sensitive to antiprotons in the energy range below 100 MeV. It has a large geometrical acceptance of about 250 cm2 sr because of its isotropic acceptance for particles. The particle identification scheme for antiprotons relies on a combination of Bragg curve spectroscopy and the characteristics of the annihilation process. In order to verify the detection principle, a prototype detector with a reduced number of channels was tested at a stationary proton beam. Its energy resolution was found to be less than 1 MeV for stopping protons of about 50 MeV energy. We give an overview of the AFIS mission and explain the working principle of the detector. We also discuss the results from the beam test.