A modular telescope facility to investigate the cosmic ray decoherence curve

Abstract

A: This paper describes the use of a set of small cosmic ray detectors for the measurement of the decoherence curve, i.e. the probability of observing coincidence events between pairs of particles from an extensive air shower as a function of the separation distance between them. Individual detection modules were arranged into 15 telescopes located in various positions, such as to cover nominal separation distances between 0.5 and about 25 m with a fine mesh. A measurement of the decoherence curve has been carried out during a period of approximately 24 days at an altitude close to the sea level, with the detectors located in a large lecture hall of the Physics Department, below a concrete roof. Results were also compared to theoretical simulations of extensive air showers based on Corsika. Performance of the method is discussed, with possible extension of this technique to provide a low-cost facility for the investigation of the decoherence curve at even larger distances.

Measurements of decoherence in small sea-level extensive air showers

“…The usual air shower decoherence experiment involves triggering two detectors and determining the coincidence rate of those triggers as a function of detector spacing (e.g. [4]). This is historically important as it can demonstrate the large lateral spread of particles in a shower.…”

“…As a result, the largest practical spacing is often determined by the low coincidence trigger rate at large spacings, or the physical space available. A good example of a recent experiment is that of Riggi et al [4]. They used 0.04 m 2 scintillators with spacings up to 26 m in a large lecture hall.…”

“…This type of experiment is of interest historically but, also, it is now accessible in teaching laboratories using relatively affordable hardware (e.g. [4]). The resulting relationship between coincidence rate and separation is the 'decoherence curve' and this is often the topic of comic ray studies in undergraduate teaching laboratories.…”

Particle correlation and intermittency in simulated cosmic ray showers

“…Figure 2 presents the decoherence curve recently measured by Riggi and co-workers [17] and, for comparison, the old historical measurements of Auger [18] and Kolhörster [19]. Riggi used an array of 15 telescopes consisting of two 20 × 20 cm 2 scintillation counters placed one above the other and recorded the number of coincidences of each pair of telescopes for almost a month.…”

“…2 by the solid line is equal to 1. The different experimental results were obtained under different conditions, at different elevations above sea [17] (black dots), [18] (empty circles) and [19] (squares). The line represents −1 level and with different detector sizes and therefore were renormalised accordingly.…”