The compound nucleus is formed at the same excitation energy two ways: with protons on

PHYSICS · Multi-part · Fermi University Physics · Scientific Practice & Experimental Methods · Nuclear Physics · Uncertainty in measurement

The Nucleus Resolved, Ch Reaction mechanisms: resonances, the compound nucleus, direct reactions and the optical model

Problem

The compound nucleus

^{60}\mathrm{Ni}^*

is formed at the same excitation energy

E^* = 20.0\,\mathrm{MeV}

two ways: with protons on

^{59}\mathrm{Co}

, and with alpha particles on

^{56}\mathrm{Fe}

. The relative yields (arbitrary but internally consistent units, each with a statistical uncertainty of

\pm 8\%

) into three exit channels are: Proton entrance:

(x,n)=100

(x,2n)=46

(x,pn)=29

. Alpha entrance:

(x,n)=94

(x,2n)=43

(x,pn)=31

. ((a)) Form the ratios

(x,2n)/(x,n)

and

(x,pn)/(x,n)

for each entrance channel (these ratios do not need the absolute beam normalisation, which differs between the two experiments). ((b)) Estimate the uncertainty on each ratio from the two

\pm8\%

yields, and decide whether the two entrance channels agree with each other within that uncertainty. ((c)) State what this decision implies for Bohr's independence hypothesis for this compound nucleus.

Related theory

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