Observation of the shadowing of cosmic rays by the Moon using a deep underground detector

The ANTARES neutrino telescope is the largest Cherenkov detector currently in operation in Mediterranean sea. The search for point-like neutrino sources is one of the telescope goals. For this reason, both the detector angular resolution and the pointing accuracy need a proper estimation. Measuring the deficit of the atmospheric muons in the direction of the Moon induced by the absorption of primary cosmic rays, the so called Moon shadow, allows to evaluate the pointing performance of the telescope. In this contribution we show the result of the analysis of the data taken between 2007 and 2016. The Moon shadow is detected with 3.5σ significance. This is the first measurement of the ANTARES angular resolution for atmospheric muons and its absolute pointing using a celestial calibration source. The presented results confirm the good pointing performance of the detector as well as the expected angular resolution.

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Cosmogenic Activation in Double Beta Decay Experiments

Universe ◽

10.3390/universe6100162 ◽

2020 ◽

Vol 6 (10) ◽

pp. 162

Author(s):

Susana Cebrián

Keyword(s):

Cosmic Rays ◽

Beta Decay ◽

Double Beta Decay ◽

Nuclear Process ◽

Different Types ◽

Deep Underground ◽

Cosmogenic Activation ◽

Materials Used ◽

Set Up ◽

Copper Lead

Double beta decay is a very rare nuclear process and, therefore, experiments intended to detect it must be operated deep underground and in ultra-low background conditions. Long-lived radioisotopes produced by the previous exposure of materials to cosmic rays on the Earth’s surface or even underground can become problematic for the required sensitivity. Here, the studies developed to quantify and reduce the activation yields in detectors and materials used in the set-up of these experiments will be reviewed, considering target materials like germanium, tellurium and xenon together with other ones commonly used like copper, lead, stainless steel or argon. Calculations following very different approaches and measurements from irradiation experiments using beams or directly cosmic rays will be considered for relevant radioisotopes. The effect of cosmogenic activation in present and future double beta decay projects based on different types of detectors will be analyzed too.

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Shower production by penetrating cosmic rays

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1939.0122 ◽

1939 ◽

Vol 172 (951) ◽

pp. 568-582 ◽

Cited By ~ 7

Keyword(s):

Cosmic Rays ◽

Cosmic Ray ◽

Probable Mechanism ◽

Transition Curve ◽

Cascade Process ◽

Initial Part ◽

Deep Underground ◽

Direct Collision ◽

Cascade Multiplication

The transition curve, giving the cosmic-ray shower intensity under increasing thicknesses of lead, rises to a maximum at about 1.6 cm., falls fairly rapidly to 5 cm., and then falls off more slowly, maintaining a finite intensity at very great thicknesses. Further, the occurrence of showers deep underground has long been established (Follett and Crawshaw 1936; Ehmert 1937). The showers forming the initial part of the transition curve (up to about 5 cm. of lead) are adequately accounted for by cascade multiplication from incident electrons or photons (Bhabha and Heitler 1937). Some other mechanism, however, is required to explain the occurrence of showers under much greater thicknesses. It is generally recognized that the showers forming the tail of the transition curve are associated with the penetrating component, and the theory developed by Bhabha (1938) suggests a probable mechanism, whereby a mesotron knocks-on an electron in a direct collision; the electron subsequently producing a shower through the normal cascade process. It has already been shown that the production of secondaries (small showers) by the penetrating component can be accurately explained by this knock-on mechanism (Wilson, J. G. 1938; Trumpy 1938; Hopkins, Nielsen and Nordheim 1939).

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