Progress in high-energy cosmic ray physics

Mollerach, Silvia; Roulet, Esteban

doi:10.1016/j.ppnp.2017.10.002

Cited by 62 publications

(82 citation statements)

References 173 publications

(245 reference statements)

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“…Recent reviews which provide additional details on ultrahigh energy cosmic rays, in particular their mass composition and source candidates, are Refs. [43,44]. Some historical background can be found in Refs.…”

Section: Introductionmentioning

confidence: 99%

Cosmic ray models

Kachelrieß

Semikoz

2019

Progress in Particle and Nuclear Physics

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We review progress in high-energy cosmic ray physics focusing on recent experimental results and models developed for their interpretation. Emphasis is put on the propagation of charged cosmic rays, covering the whole range from ∼ (20 − 50) GV, i.e. the rigidity when solar modulations can be neglected, up to the highest energies observed. We discuss models aiming to explain the anomalies in Galactic cosmic rays, the knee, and the transition from Galactic to extragalactic cosmic rays.

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Section: Introductionmentioning

confidence: 99%

Cosmic ray models

Kachelrieß

Semikoz

2019

Progress in Particle and Nuclear Physics

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“…Furthermore, photodisintegration for the heavier elements (see the curve segments corresponding to UHECR energies in Fig. 1 of [51]) and pair production for protons [54] both set the maximum distance to the sources of the highest energy UHECRs at around 1Gpc (i.e., the sources should be within the local universe), but this does not prevent CRs originating further out from reaching us altogether. Photodisintegration does not reduce the Lorentz factors of the composite nuclei that it breaks up, so the CRs from cosmological sources ( 1Gpc) will all turn into ultra-relativistic protons, which will also become partially energydepleted through the pair production effect until their energies fall to around 5EeV, below which the pair production attenuation length rises to tens of Gpc (see Fig.…”

Section: Compositionmentioning

confidence: 99%

“…Photodisintegration does not reduce the Lorentz factors of the composite nuclei that it breaks up, so the CRs from cosmological sources ( 1Gpc) will all turn into ultra-relativistic protons, which will also become partially energydepleted through the pair production effect until their energies fall to around 5EeV, below which the pair production attenuation length rises to tens of Gpc (see Fig. 8 of [54]; and also discussions therein along similar lines, although it is the enhanced photodisintegration at EM-active sources that was envisioned there). Consequently, cosmological sources could possibly provide the (extra-galactic) pure proton injection necessary to explain the ankle feature in the UHECR spectrum (at around 5EeV), as required by the dip model [55,56].…”

Section: Compositionmentioning

confidence: 99%

Gravitational slingshots around black holes in a binary

Zhang

2020

Eur. Phys. J. Plus

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The speed gain of a test mass from taking a gravitational slingshot around a celestial object (scattering centre) increases with the latter's speed and compactness (stronger deflection of the mass' trajectory becomes possible without it hitting the surface of the object). The black holes (BHs) in a tight binary (consisting of two black holes; we are not considering X-ray binaries), themselves moving at relativistic speeds, represent optimal scattering centres. Therefore, a sub-population of accreting matter particles, swept up into chaotic orbits around a BH binary, might repeatedly take slingshots and become accelerated to ultra-relativistic speeds (as seen by observers on Earth), ultimately escaping from the binary, as well as the fate of being devoured by a BH. The escaped particles can plausibly be observed on Earth as ultra-high-energy cosmic rays (UHECRs). Investigating such a possibility would require general relativistic slingshot formulae due to the high speeds involved and the close encounters with BHs. We derive them in this paper, and show that the percentage gain per slingshot in a particle's Lorentz factor remains undiminished even as the particle energizes up, thus demonstrating that the slingshot mechanism can in principal accelerate particles to extreme energies.PACS. 9 8.70.Sa -9 5.85.Ry -0 4.70.Bw -0 4.90.+e IntroductionUltra-high energy cosmic rays (UHECRs) [1,2] have garnered tremendous interest since they would suffer less deflection by the galactic and intergalactic magnetic fields, so their paths point roughly back at their sources, potentially helping to identify and elucidate some undoubtedly interesting extremely energetic astrophysical processes, but the nature of which have so far remained an open question. Nevertheless, more recent observations had revealed a wealth of important features in the UHECR spectrum, composition, anisotropy and (lack of) counterparts, that can guide our modelling efforts. For example, the most straightforward top-down approach, where some type of extremely heavy beyond-the-standard-model particle decays into lighter ones whose rest masses add up to only a small fraction of the parent particle's rest mass, is now somewhat disfavoured. Firstly, such processes tend to produce copious amounts of concomitant high energy photons and neutrinos, which are absent observationally [3,4]. Also, composition studies show that there should be large amounts of intermediate mass nuclei at the very highest energies [5,6,7], which would be rather perplexing in the decay picture, as one must wonder why ultra-relativistic nucleons (as decay products) all move in the same direction and remain bound inside a nuclei, instead of simply flying off in all directions.The bottom-up alternative of accelerating initially low energy particles is no less challenging. The macroscopic high energies reaching into hundreds of EeVs means that we need to find an extremely energy-dense environment that can boost the particles to exceptionally high Lorentz factors. Thankfully though, the candidate...

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“…Cosmic rays, dominantly protons and heavier atomic nuclei, arrive at earth with an energy that spans some 12 orders of magnitude, from a few hundred MeV (10 8 eV) to 100 EeV (10 20 eV) [106][107][108], 16 30. Cosmic rays Measurements of flux with air shower experiments in the knee region differ by as much as a factor of two, indicative of systematic uncertainties in interpretation of the data.…”

Section: Basic Principles Of Cosmic Ray Detectionmentioning

confidence: 99%

A Letter of Intent for MATHUSLA: a dedicated displaced vertex detector above ATLAS or CMS.

Alpigiani

Ball²,

Barak³

et al. 2018

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In this Letter of Intent (LOI) we propose the construction of MATHUSLA (MAssive Timing Hodoscope for Ultra-Stable neutraL pArticles) [1], a dedicated large-volume displaced vertex detector for the HL-LHC on the surface above ATLAS or CMS. Such a detector, which can be built using existing technologies with a reasonable budget in time for the HL-LHC upgrade, could search for neutral long-lived particles (LLPs) with up to several orders of magnitude better sensitivity than ATLAS or CMS, while also acting as a cutting-edge cosmic ray telescope at CERN to explore many open questions in cosmic ray and astro-particle physics. We review the physics motivations for MATHUSLA and summarize its LLP reach for several different possible detector geometries, as well as outline the cosmic ray physics program. We present several updated background studies for MATHUSLA, which help inform a first detector-design concept utilizing modular construction with Resistive Plate Chambers (RPCs) as the primary tracking technology. We present first efficiency and reconstruction studies to verify the viability of this design concept, and we explore some aspects of its total cost. We end with a summary of recent progress made on the MATHUSLA test stand, a small-scale demonstrator experiment currently taking data at CERN Point 1, and finish with a short comment on future work.

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Progress in high-energy cosmic ray physics

Cited by 62 publications

References 173 publications

Cosmic ray models

Cosmic ray models

Gravitational slingshots around black holes in a binary

A Letter of Intent for MATHUSLA: a dedicated displaced vertex detector above ATLAS or CMS.

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