Head and neck tumors

Ord, Robert A.; Fernandes, Rui

doi:10.1017/cbo9780511545757.011

Cited by 1 publication

(2 citation statements)

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“…Turning to the radiation fields, later work [14], has shown that the IR intensity is a factor 2 lower than assumed in [2]. However, the IR affects the ensuing gamma ray spectrum only above about 10 3 GeV and thus at higher energies than of interest here.…”

Section: Effect Of Maximum Energy and Massmentioning

confidence: 77%

“…The profile of the attenuation mean free path (λ) versus energy for both protons and iron nuclei has been known for many decades. Using recent calculations [14,15], for protons λ falls from its red-shift value of 4000 Mpc to 1000 Mpc at 10 EeV, 200 Mpc Figure 1: Comparison of the Fermi-LAT EG diffuse gamma ray spectrum [4], denoted FL with that derived earlier by us [13] and denoted 'OWZ'. 'FL(corr)' relates to the Fermi-LAT spectrum corrected for AGN.…”

Section: Effect Of Maximum Energy and Massmentioning

confidence: 89%

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Ultra-high energy cosmic rays and the extragalactic gamma ray flux

Erlykin¹,

Wolfendale²

2014

J. Phys. G: Nucl. Part. Phys.

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Ultra-high energy cosmic rays interacting with the radiation fields in the universe cause electromagnetic cascades resulting in a flux of extragalactic gamma rays, detectable to some 100 GeV. Recent precise measurements of the extragalactic gamma ray flux by Fermi-LAT, coupled with estimates of the background from active galactic nuclei of various types, allows limits to be set on the cascade component. By comparison with prediction and, making various assumptions, ie taking a particular model, limits can be set on the maximum energy to which ultra-high energy particles can be accelerated.If our model is correct, it is unlikely that the maximum energy is above 100 EeV, in turn, the apparent 'GZK' cut-off in the measured ultra-high energy spectrum could instead be due to a fall-off in the intrinsic emergent particle spectrum. However, it is not possible to be dogmatic at the present time because of uncertainty in many of the parameters involved. We have used recent estimates of the range of parameters and have found that although our model has parameters in the allowable ranges the uncertainties are so large that our result is not unique, although the method is satisfactory. The result must thus, so far, be taken as an indication only.

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Section: Effect Of Maximum Energy and Massmentioning

confidence: 77%