Four Decades of Computing in Subnuclear Physics - from Bubble Chamber to LHC

This manuscript addresses selected aspects of computing for the reconstruction and simulation of particle interactions in subnuclear physics. Based on personal experience with experiments at DESY and at CERN, I cover the evolution of computing hardware and software from the era of track chambers where interactions were recorded on photographic film up to the LHC experiments with their multi-million electronic channels

Can the neutrino speed anomaly be defended?

The OPERA collaboration reported [1] a measurement of the neutrino velocity exceeding the speed of light by 0.025%. For the 730 km distance from CERN in Geneva to the OPERA experiment an early arrival of the neutrinos of 60.7 ns is measured with an accuracy of \pm6.9 ns (stat.) and \pm7.4 ns (sys.). A basic assumption in the analysis is that the proton time structure represents exactly the time structure of the neutrino flux. In this manuscript, we challenge this assumption. We identify two main origins of systematic effects: a group delay due to low pass filters acting on the particular shape of the proton time distribution and a movement of the proton beam at the target during the leading and trailing slopes of the spill

Saddle-nodes and period-doublings of smale horseshoes: a case study near resonant homoclinic bellows

Abstract In unfoldings of resonant homoclinic bellows interesting bifurcation phenomena occur: two suspensed Smale horseshoes can collide and disappear in saddle-node bifurcations (all periodic orbits disappear through saddle-node bifurcations, there are no other bifurcations of periodic orbits), or a suspended horseshoe can go through saddle-node and period-doubling bifurcations of the periodic orbits in it to create an additional "doubled horseshoe"

Lin's method for heteroclinic chains involving periodic orbits

We present an extension of the theory known as Lin's method to heteroclinic chains that connect hyperbolic equilibria and hyperbolic periodic orbits. Based on the construction of a so-called Lin orbit, that is, a sequence of continuous partial orbits that only have jumps in a certain prescribed linear subspace, estimates for these jumps are derived. We use the jump estimates to discuss bifurcation equations for homoclinic orbits near heteroclinic cycles between an equilibrium and a periodic orbit (EtoP cycles)