Why is solar cycle 24 an inefficient producer of high-energy particle events? Rami Vainio, Osku Raukunen, Allan J. Tylka, William F. Dietrich and Alexandr Afanasiev A&A, 604 (2017) A47 Published online: 01 August 2017 DOI: 10.1051/0004-6361/201730547