Bohr stopping formula

In modern notation, Bohr s stopping formula then reads... 

Despite the apparent similarity of the Bohr and the Bethe stopping power formulae, the conditions of their validity are rather complimentary than the same. Bloch [23] pointed out that Born approximation requires the incident particle velocity v ze jh, the speed of a Is electron around the incident electron while the requirement of Bohr s classical theory is exactly the opposite. For heavy, slow particles, for example, fission fragments penetrating light media, Bohr s formula has an inherent advantage, although the typical transition energy has to be taken as an adjustable parameter. 

Figure 1 shows a comparison between experimental stopping data and equations (7) and (11). It is seen that over a broad range of beam energies, Bohr s classical formula is superior to Bethe s when the same /-value is inserted. 

Fig. 1. Stopping force on oxygen ions in aluminium Comparison of Bohr and Bethe formulae with measurements from numerous laboratories compiled in Ref. [6]. From Ref. [7].

The basic stopping power formula of Bethe has a structure similar to that of Bohr s classical theory [cf. Eq. (2)]. The kinematic factor remains the same while the stopping number is given hy B = Zln(2mv /7) for incident heavy, nonrelativistic particles. The Bethe... 

Bloch [8.1] derived a formula for the stopping power which is valid for all values of X, and which is therefore a synthesis of the quantal result of Bethe [2.8] and the classical stopping power deduced by Bohr [6.21]. Bloch [8.1] found that the transition between the classical and the quantal results can be accounted for by setting... 

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