Observations on extensive air showers VII. The lateral distribution of energy in the electron-photon component

2019

EPJ Web Conf.

The greater part of this paper is concerned with a historical discussion of the development of the search for the origins of the highest-energy cosmic-rays together with a few remarks about future prospects.Additionally, in section 6, the situation with regard to the mass composition and energy spectrum at the highest energies is discussed. It is shown that the change of the depth of shower maximum with energy above 1 EeV, measured using the Telescope Array, is in striking agreement with similar results from the Auger Observatory. This implies that either the mean mass of cosmic rays is becoming heavier above ~4 EeV or that there is a change in details of the hadronic interactions in a manner such that protons masquerade as heavier nuclei. A long-standing controversy is thus resolved: the belief that pure protons dominate the mass distribution at the highest energies is no longer tenable.  Corresponding author: a.a.watson@leeds.ac.uk After World War I, the work of Hess was greatly extended by the German physicist, Erich Regener. At a Royal Society Discussion Meeting in 1931 [3] Ernest Rutherford noted that 'there was now reliable data on cosmic ray absorption in water thanks to the far-reaching experiments of Regener'. Shortly after, Regener pioneered balloon flights in which Geiger counters were carried to great altitudes. He encased his equipment in cellophane to protect against low temperatures: his equipment cooled only to 17⁰ C at the highest altitudes. This was an important technical advance and solved the problems of temperature stability that had blighted similar work by Millikan. In 1935 Regener and his student Pfotzer, succeeded in flying three Geiger counters, arranged to limit the solid angle for detection to within ±20⁰, to an altitude of 22 km (~40 g cm -2 ) [4], the altitude limit probably being set by the destructive interaction of ozone with the rubber balloons. At an over-burden of ~130 g cm -2 they discovered that the coincidence rate maximised, a feature commonly referred to as the 'Pfotzer maximum'. While Pfotzer did follow up and extend this work alone, after Regener had lost his position at the University of Stuttgart because of his political views and because his wife was Jewish, it seems appropriate to refer to this, at the very least, as the Regener-Pfotzer maximum [5].This discovery, combined with the transition curves reported by Rossi [6], were explained by Bhabha and Heitler [7] who used the newly invented quantum electrodynamics to describe shower phenomena. Schmeiser and Bothe [8] were the first to point out that Rossi's curves implied that there should also be showers in airnaming them 'Luftschauer' -and showed that particles in showers were separated by up to 40 cm. Clearly Regener's ionisation curve forced the same conclusion. Kolhörster et al [9] extended the separation over which coincidences were found to nearly 80 m. Quite independently, and somewhat serendipitously, Pierre Auger and his colleagues also discovered the air-shower phenomenon. Auger's assistant, Roland Maze, a...

Section: Work With Geiger Counters In the Ukmentioning

confidence: 99%

“…A comparison of the tank (left) developed by Porter [28] and one used at the Pierre Auger Observatory. The detectors have been drawn to the same scale: figure taken from [29].…”

Section: Figmentioning

confidence: 99%

The highest-energy cosmic-rays – the past, the present and the future

2019

EPJ Web Conf.

“…The second key development made at Culham was of the water-Cherenkov detector. Credit for this work goes to N A Porter who, while a member of the team working with the Geiger-counter array, became the first to succeed in preventing bacterial growth in unfiltered water long enough to realise a stable detector [Porter, 1958]. This was achieved by enclosing the water in a cubical, sealed, box of 'Darvic', [Porter, 1958] of 1.44 m 2 read out by a single 5" diameter PMT to those used at the Pierre Auger Observatory of 10 m 2 read out by three 9" PMTs [Abraham, 2004].…”

Section: Developments At the Culham Array And Consequencesmentioning

confidence: 99%

“…5. Scale comparison of the first water-Cherenkov detectors used by Porter et al[Porter, 1958] of 1.44 m 2 read out by a single 5" diameter PMT to those used at the Pierre Auger Observatory of 10 m 2 read out by three 9" PMTs[Abraham, 2004].…”

mentioning

confidence: 99%

Extensive air showers and ultra high-energy cosmic rays: a historical review

Kampert

2012

EPJ H

Abstract. The discovery of extensive air showers by Rossi, Schmeiser, Bothe, Kolhörster and Auger at the end of the 1930s, facilitated by the coincidence technique of Bothe and Rossi, led to fundamental contributions in the field of cosmic ray physics and laid the foundation for high-energy particle physics. Soon after World War II a cosmic ray group at MIT in the USA pioneered detailed investigations of air shower phenomena and their experimental skill laid the foundation for many of the methods and much of the instrumentation used today. Soon interests focussed on the highest energies requiring much larger detectors to be operated. The first detection of air fluorescence light by Japanese and US groups in the early 1970s marked an important experimental breakthrough towards this end as it allowed huge volumes of atmosphere to be monitored by optical telescopes. Radio observations of air showers, pioneered in the 1960s, are presently experiencing a renaissance and may revolutionise the field again. In the last 7 decades the research has seen many ups but also a few downs. However, the example of the Cygnus X-3 story demonstrated that even non-confirmable observations can have a huge impact by boosting new instrumentation to make discoveries and shape an entire scientific community.

“…Credit for this development goes to N.A. Porter 5 who, while a member of the team working with the Geiger counter array at Harwell, became the first to succeed in preventing bacterial growth in unfiltered water long enough to realise a stable detector [30]. This was achieved by enclosing the water in a cubical, sealed, box of 'Darvic', a material then manufactured in the UK by ICI.…”

Section: Use Of Water-cherenkov Detectors In the Study Of Extensive A...mentioning

confidence: 99%

The discovery of Cherenkov radiation and its use in the detection of extensive air showers

Nuclear Physics B - Proceedings Supplements

2011

Cascades of charged particles are created when high-energy cosmic rays enter the earth's atmosphere: these 'extensive air-showers' are studied to gain information on the energy spectrum, arrival direction distribution and mass composition of the particles above 10 14 eV where direct observations using instruments carried by balloons or satellites become impractical. Detection of light in the visible and ultra-violet ranges of the electromagnetic spectrum plays a key role in this work, the two processes involved being the emission of Cherenkov light and the production of fluorescence radiation. In this paper I will outline some of the history of the discovery of the Cherenkov process and describe the use to which it has been put in the study of extensive air-showers at ground level.