THE SPACE ERA

(With an aim to focus on an upcoming era, the technologies, the thoughts that may help to empower mankind. The post aims to trigger the thoughts to harvest useful energy from the cosmic particles)

COSMIC RAYS

Term ‘cosmic rays’ refers to charged particles originating from space. Cosmic Rays (CR) measurements focus on three areas:

• Energy spectrum: variation of observed flux with a density
• Composition: the particle species
• Anisotropy: the distribution of arrival directions of the particles over the sky

Fluorescence light is emitted isotropically.  

A pathfinder experiment to explore the potential of radio detection for large scale applications are the Auger Engineering Radio Array (AERA).

We compare the antenna calibration measurements with simulations and develop the antenna simulation models of the Butterfly antenna station which are currently used for the radio reconstruction at AERA.

The intensity of the ionizing radiation increases with increasing altitudes, rather than decreases as is expected for sources on the earth’s surface. For example, we are dependent on model calculations of shower development for the estimate of the primary energy. Uncertainties in the geometrical reconstruction of the EAS track and atmospheric clarity are examples of experimental sources of uncertainty. The net result of these factors is that the CR energies can be estimated to within 20% at best.

Showers generated by iron nuclei develop higher in the atmosphere than those produced by protons.

The most recent measurement of the spectrum comes from the AGASA collaboration. A most important feature of the AGASA spectrum is that it extends above 10^20 eV.

EAS PHYSICS

An EAS is composed of three components:

(a) A hadronic core,

(b) An electromagnetic component and

(c) A muonic component.

The High-Resolution Fly’s Eye (HiRes) detector consists of two sites that can operate independently or as one “stereo” detector. The two sites are located at Little-Granite mountain (HiRes-I), and Camel’s Back Ridge (HiRes-II) at the U.S. Army Dugway proving grounds in Utah. While the two sites are operated independently, the data collected can be analyzed either in a monocular mode for each site or together in stereo mode. This dissertation will report on the first results from the monocular observation made by HiRes-I. The HiRes-I site

MUON PARTICLES

Muon, elementary subatomic particle similar to the electron but 207 times heavier. It has two forms, the negatively charged muon and its positively charged antiparticle. The muon was discovered as a constituent of cosmic-ray particle “showers” in 1936 by the American physicists Carl D. Anderson and Seth Neddermeyer. Because of its mass, it was at first thought to be the particle predicted by the Japanese physicist Yukawa Hideki in 1935 to explain the strong force that binds protons and neutrons together in atomic nuclei. It was subsequently discovered, however, that a muon is correctly assigned as a member of the lepton group of subatomic particles—i.e., it never reacts with nuclei or other particles through the strong interaction. A muon is relatively unstable, with a lifetime of only 2.2 microseconds before it decays by the weak force into an electron and two kinds of neutrinos. Because muons are charged, before decaying they lose energy by displacing electrons from atoms (ionization). At high-particle velocities close to the speed of light, ionization dissipates energy in relatively small amounts, so muons in cosmic radiation are extremely penetrating and can travel thousands of metres below the Earth’s surface.

Muonic Component

Muons are mainly produced via the decay of charged pions (π± −→ μ± + ν).  Charged kaons decay can also produce muons, either directly, or by producing charged pions which in turn decay into muons. Muons ionization losses are small and their decay times are long. Therefore, they survive to reach the ground. Although the number of electrons in the shower is much greater than the number of muons, the fact that muon are much more penetrating than electrons means that they can be selectively detected by underground detectors (e.g. scintillators buried underground or shielded by an absorber such as lead.) The number of muons at ground level depends upon the energy and the mass composition of the incident CR. Mass composition measurements done by ground arrays are based on this dependence. Air fluorescence detectors, such as HiRes, can not measure the muon content of the EAS. Thus, muons are largely irrelevant to our measurement and will not be discussed further.

Reference :

1www.britannica.com

2THE ENERGY SPECTRUM OF ULTRA HIGH ENERGY COSMIC RAY by Tareq Ziad AbuZayyad