Interactions Of Primary Cosmic Rays Research Articles

Cosmic ray issues for accelerator experiments

Cosmic ray experimentalists seek to understand the physics of the first interaction of primary cosmic rays with air nuclei a) to comprehend the character of particle interactions at very high energies, and b) to correctly simulate that interaction in order to properly interpret data collected (in most cases) under an overburden of atmosphere. With regard to b), John Ellis (CERN) has suggested that the cosmic ray community develop a compendium of specific questions to address to the accelerator experiment community, in the context of current and planned accelerator experiments at LHC, RHIC, and the Tevatron. This paper is an attempt to begin such a discussion.

Particle Astrophysics with the AMANDA neutrino telescope

Particle Astrophysics with the AMANDA neutrino telescope

Superconductivity and high-Tc superconductors

Superconductivity and high-Tc superconductors

Particle Astrophysics with the AMANDA neutrino telescope

Particle Astrophysics with the AMANDA neutrino telescope

Observation of atmospheric neutrinos

Atmospheric neutrinos arise from the decay of secondaries (π, K and μ) produced by primary cosmic-ray interactions in the atmosphere. In the energy range below 1GeV, where all secondaries decay, we roughly expect that (v μ + v μ )/(v e + v e ) ≃2. This is because a π-decay produces a v μ and a μ; the μ, when it decays, produces another v μ and a v e . These neutrinos enter into the detector from all directions nearly isotropically. The path length of the neutrinos (from the production point to the detector) ranges from a few km to 13000km, the diameter of the earth. In this article we describe recent measurements of atmospheric neutrinos by large underground detectors. Some of the experiments have observed that the (v μ + v μ )/(v e + v e ) ratio is significantly smaller than expected. The interpretation of these interesting results, the future prospect on atmospheric neutrinos and related neutrino physics are also described. In most parts of this article, when mention is made of neutrinos, we imply both neutrinos and antineutrinos.

Neutron spectra in the atmosphere from interactions of primary cosmic rays

Spectra of neutrons from interactions of primary cosmic rays in the earth's atmosphere are calculated with the Monte Carlo model fluka for various depths down to sea level. We discuss the environmental models describing the primary cosmic ray spectrum and details of the calculations. Neutron energy spectra are presented for different depths in the atmosphere and for different geographical locations. By comparing results of calculations to measurements on neutron spectra it is shown that fluka may serve as an important tool for the estimation of the radiation environment in the atmosphere.

Secondary radiation environments in heavy space vehicles and instruments

Secondary radiations produced by the interactions of primary cosmic rays and trapped protons with spacecraft materials and detectors provides an important, and sometimes dominant, radiation environment for sensitive scientific instruments and biological systems. In this paper the success of a number of calculations in predicting a variety of effects will be examined. The calculation techniques include Monte Carlo transport codes and semi-empirical fragmentation calculations. Observations are based on flights of the Cosmic Radiation Environment and Activation Monitor at a number of inclinations and altitudes on Space Shuttle. The Shuttle experiments included an active cosmic-ray detector as well as metal activation foils and passive detector crystals of sodium iodide which were counted for induced radioactivity soon after return to earth. Results show that cosmic-ray secondaries increase the fluxes of particles of linear energy transfer less than 200 MeV/(gm cm −2), while the activation of the crystals is enhanced by about a factor of three due to secondary neutrons. Detailed spectra of induced radioactivity resulting from spallation products have been obtained. More than a hundred significant radioactive nuclides are included in the calculation and overall close agreement with the observations is obtained.

The measurement of the decorrelation function in underground muon pairs as a probe of primary cosmic ray interactions

We discuss the measurement of the average angle within pairs of muons detected in underground experiments versus their relative distance, as a tool for studying primary Cosmic Ray interactions. We propose to call 〈 Φ( d)〉 “decorrelation” function. Under simplifying approximation, the decorrelation function can be computed analytically to show its dependence on details of cosmic ray interactions as well as on the propagation in the rock. We argue that this new measurement is useful in a real experiment, complementing traditional ones like the decoherence function.

Study of the effect of relativistic time dilation on cosmic ray muon flux—An undergraduate modern physics experiment

An experiment to study the effect of relativistic time dilation on secondary muon fluxes observed at different altitudes is described in this article. Muons, produced as secondary particles from the interaction of primary cosmic rays with the upper atmosphere, form a natural and abundant source of subatomic ‘‘clocks’’ moving at very high speeds. The measured muon flux on a mountain relative to that measured at sea level can be compared to predictions from calculations that take into account the relativistic time dilation in the muon frame. Situations under which such an experiment can be successfully performed are explored with a day-long field trip to a nearby mountain. This experiment has been developed at Smith College as a module in the Five College cooperative undergraduate advanced laboratory course (other participating institutions are Amherst College, Mount Holyoke College, and the University of Massachusetts).

On the Heavy Primary Cosmic Ray Interactions in Nuclear Emulsions

The interactions of heavy primary particles in cosmic rays are analyzed by the method of nuclear emulsions. From this analysis, some characteristics of nuclear structure are obtained. The ratio of the number of fragment alpha particles to that of fragment protons produced by incident heavy primaries (Z between 6 and 9) is about 0.37 for N h ≤7 events, and this value is in good agreement with the results of other experiments. The transparency of medium nucleus is estimated to be about 30%. The relation between incident energies and average number of produced mesons is compared with other accerelator data. The experimental results are well interpreted from the view that the medium nucleus having charge 6 to 9 is constructed from a group of some complete helium nuclei if the charge of medium nucleus is evem (alpha particle model), while the odd charged medium nucleus is composed of some helium nuclei and a helium nucleus accompanied by an extra proton.