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where <br />

is in £<br />

© and ¢ <br />

<br />

¢ £<br />

¦ ¡ £§<br />

is given by the Bethe-Bloch formula [8]:<br />

<br />

£<br />

<br />

<br />

<br />

<br />

¨ © <br />

<br />

¢<br />

¤¢<br />

<br />

in which ¦ ¢ is the sum of the discrete processes’ contributions<br />

<br />

and the correction term (from<br />

¡ ¡<br />

knock-on electrons) causes the <br />

energy loss <strong>to</strong> become constant for , i.e. upon entering<br />

the Fermi plateau [30], which is reached at around 10 GeV for muons. Both ¢ and ¦ ¨¢ can<br />

<br />

be<br />

<br />

£ © © ¦ ¢¡ © £<br />

£ © ©<br />

approximated with constants. Typically and .<br />

By solving Eq. 32, we get the mean range of a muon starting with energy ¢ and decaying with<br />

<br />

energy ¢ :<br />

m<br />

10 4<br />

10 3<br />

10 2<br />

10<br />

1 10 10 2<br />

10 3<br />

10 4<br />

<br />

10 5<br />

18<br />

<br />

(33)<br />

<br />

10<br />

GeV<br />

6<br />

Figure 9: Mean range of a muon in ice as a function of its energy.<br />

¡<br />

¢ ¢ ¢ <br />

¦<br />

¢ ¡ ¢ § <br />

¡ ¢ § (34)<br />

¢<br />

¤¢ ¦<br />

©<br />

§¤£ ¢<br />

where is the critical energy above which s<strong>to</strong>chastic processes dominate ¤ over ionization.<br />

Below ¢ § , the muon range increases linearly with the muon energy, and above,<br />

<br />

it<br />

¢ ¢ <br />

is<br />

<br />

proportional<br />

¢ §<br />

<strong>to</strong> . When , the fluctuations are large and a Monte Carlo simulation £¢<br />

is necessary<br />

<strong>to</strong> take in<strong>to</strong> account the s<strong>to</strong>chastic nature of the energy loss.<br />

Since the muons considered here have high energies, so do the particles they produce during<br />

their propagation through ice. As a result, they are boosted in the same direction and the<br />

Cherenkov light they emit is sent out at an angle relative <strong>to</strong> the muon close <strong>to</strong> as well. The<br />

smearing induced is of the order of a few degrees (see [26, 31]).

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