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I was going through a research paper explaining the possible reasons for origin of knee in the cosmic ray spectrum. I came across this statement "nuclei-initiated showers have smaller fluctuations in their development and the sharp cutoff in the primary energy spectrum should not be diluted when transferred to the EAS size spectrum."

Could someone please explain what is nucleus initiated shower and why nucleus initiated showers have lesser fluctuations?

I have gone through a lot websites regarding this question, none seem to explain it satisfactorily.

Thanks for the help.

Tejas P
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1 Answers1

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EAS means Extensive Air Showers, which are the particle and photon cascades initiated in the atmosphere by very high energy cosmic rays, and provide the main means of detecting them with earth based detectors.

The properties of air showers caused by gamma rays, protons and heavier nuclei all have different characteristics. I can't tell exactly what is meant by your quote out of the surrounding context, but it is either contrasting nuclei with proton induced showers (which seems most likely in a discussinon about the one of the cosmic ready spectrum) , or hadron showers generally with gamma ray showers (less likely: gamma rays are not thought to be a significant part of cosmic rays at knee energies).

PhillS
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  • Thanks for your answer. Could you please explain what are nuclei initiated showers and why they have lesser fluctuations? Here is the link to the paper for your reference https://cds.cern.ch/record/493111/files/0103477.pdf – Tejas P Apr 02 '17 at 10:35