Simulation of ultra-high energy photon propagation in the geomagnetic field

The identification of primary photons or specifying stringent limits on the photon flux is of major importance for understanding the origin of ultra-high energy (UHE) cosmic rays. UHE photons can initiate particle cascades in the geomagnetic field, which leads to significant changes in the subsequent atmospheric shower development. We present a Monte Carlo program allowing detailed studies of conversion and cascading of UHE photons in the geomagnetic field. The program named PRESHOWER can be used both as an independent tool or together with a shower simulation code. With the stand-alone version of the code it is possible to investigate various properties of the particle cascade induced by UHE photons interacting in the Earth’s magnetic field before entering the Earth’s atmosphere. Combining this program with an extensive air shower simulation code such as CORSIKA offers the possibility of investigating signatures of photon-initiated showers. In particular, features can be studied that help to discern such showers from the ones induced by hadrons. As an illustration, calculations for the conditions of the southern part of the Pierre Auger Observatory are presented. Program summary

[1]  Engel,et al.  Nucleus-nucleus collisions and interpretation of cosmic-ray cascades. , 1982, Physical review. D, Particles and fields.

[2]  M. Stearns.  Mean Square Angles of Bremsstrahlung and Pair Production , 1949 .

[3]  Wlodek Bednarek.  Cascades in the Earth’s magnetosphere initiated by photons with the parameters of the highest energy AGASA events , 2002 .

[4]  John Linsley,et al.  Evidence for a primary cosmic-ray particle with energy 10**20-eV , 1963 .

[5]  A. B. Migdal,et al.  Bremsstrahlung and pair production in condensed media at high-energies , 1956 .

[6]  J. Blümer.  Cosmic rays at the highest energies and the Pierre Auger Observatory , 2003 .

[7]  A. Hillas.  Shower Simulation: Lessons from MOCCA , 1997 .

[8]  Joseph K. Daugherty,et al.  Pair production in superstrong magnetic fields , 1983 .

[9]  Todor StanevH.P. Vankov.  Nature of the highest energy cosmic rays , 1997 .

[10]  N. Kalmykov,et al.  Quark-Gluon String Model and EAS Simulation Problems at Ultra-High Energies , 1997 .

[11]  N. Inoue,et al.  Ultrahigh energy gamma rays in the geomagnetic field and atmosphere , 2003 .

[12]  T. Erber,et al.  High-Energy Electromagnetic Conversion Processes in Intense Magnetic Fields , 1966 .

[13]  C. W. Kilmister,et al.  Radiation from relativistic electrons , 1986 .

[14]  Guenter Sigl,et al.  Origin and propagation of extremely high-energy cosmic rays , 1998 .

[15]  Xavier Bertou,et al.  LPM effect and pair production in the geomagnetic field: a signature of ultra-high energy photons in the Pierre Auger Observatory , 2000 .

[16]  M. Kobal.  A thinning method using weight limitation for air-shower simulations , 2001 .

[17]  William H. Press,et al.  Numerical recipes , 1990 .

[18]  A. Borsellino.  Momentum Transfer and Angle of Divergence of Pairs Produced by Photons , 1953 .

[19]  Fletcher,et al.  SIBYLL: An event generator for simulation of high energy cosmic ray cascades. , 1994, Physical review. D, Particles and fields.

[20]  Colin J. Lambert,et al.  Interactions of high-energy ( E > 5 × 10 19 eV) photons in the Earth's magnetic field , 1981 .