C. Dobrigkeit

Determination of the calorimetric energy in extensive air showers

Abstract The contribution of different components of an air shower to the total energy deposit in the atmosphere, for different angles and primary particles, was studied using the CORSIKA air shower simulation code. The amount of missing energy, parameterized in terms of the calorimetric energy, was calculated. The results show that this parameterization varies less than 1% with angle or observation level. The dependence with the primary mass is less than 5% and, with the high energy hadronic interaction model, less than 2%. The systematic error introduced by the use of just one parameterization of the missing energy correction function, for an equal mixture of proton and iron at 45°, was calculated to be below 3%. We estimate the statistical error due to shower-to-shower fluctuations to be about 1%.

A new type of nuclear interactions in the ΣEγ≳1014 eV region

Centauro‐type and Mini‐Centauro‐type events are reported and discussed. They are events in which nuclear‐active particles (i.e. hadrons which do not undergo rapid photon decays) are produced without any sign of accompanying neutral pion emission. Estimated hadron multiplicity is ∠100 for Centauro‐type and ∠15 for Mini‐Centauro‐type.Up to the present moment, 5 examples of Centauro and 13 of Mini‐Centauro have been observed in the two‐storey emulsion chambers exposed on Mt. Chacaltaya, Bolivia (5220 m above sea level).The experimental results on energy and angular distributions are in agreement with the hypothesis that this type of events occur through production and decay of a fire‐ball with a rest energy of (200∠300) GeV/c2 for Centauro and ∠30 GeV/c2 for Mini‐Centauro events.

Autonomous RPCs for a Cosmic Ray ground array

We report on the behaviour of Resistive Plate Chambers (RPC) developed for muon detection in ultra-high energy cosmic ray (UHECR) experiments. The RPCs were developed for the MARTA project and were tested on field conditions. These RPCs cover an area of

Three-dimensional nucleonic cascade induced by one single nucleon in the atmosphere

1.5 \times 1.2\,{m^2}

Baryon pair production with large decay Q‐value

and are instrumented with 64 pickup electrodes providing a segmentation better than

MARTA: a high-energy cosmic-ray detector concept for high-accuracy muon measurement

20\,

Cosmic ray physics in Brazil

cm. By shielding the detector units with enough slant mass to absorb the electromagnetic component in the air showers, a clean measurement of the muon content is allowed, a concept to be implemented in a next generation of UHECR experiments. The operation of a ground array detector poses challenging demands, as the RPC must operate remotely under extreme environmental conditions, with limited budgets for power and minimal maintenance. The RPC, DAQ, High Voltage and monitoring systems are enclosed in an aluminium-sealed case, providing a compact and robust unit suited for outdoor environments, which can be easily deployed and connected. The RPCs developed at LIP-Coimbra are able to operate using a very low gas flux, which allows running them for few years with a small gas reservoir. Several prototypes have already been built and tested both in the laboratory and outdoors. We report on the most recent tests done in the field that show that the developed RPCs have operated in a stable way for more than 2 years in field conditions.

Analysis of the hadronic energy spectrum in high‐energy cosmic‐ray families detected by emulsion chambers

Using a Feynman-like procedure of ordered exponential operators the authors solve the three-dimensional diffusion equation for the nucleonic cascade induced by one single nucleon in the atmosphere.

Multiple meson production in the Σ Eγ≳2×1013 eV region

Events of a new type have been observed by the chacaltaya Emulsion Chamber Experiment,1,2 which can consistently be interpreted as ’’baryon’’ pair decay of a heavy intermetiate state of rest mas 20–30 GeV/c2.

Nuclear Interactions in Super High Energy Region

A new concept for the direct measurement of muons in air showers is presented. The concept is based on resistive plate chambers (RPCs), which can directly measure muons with very good space and time resolution. The muon detector is shielded by placing it under another detector able to absorb and measure the electromagnetic component of the showers such as a water-Cherenkov detector, commonly used in air shower arrays. The combination of the two detectors in a single, compact detector unit provides a unique measurement that opens rich possibilities in the study of air showers.