(a) A heavy-water detector registers a neutrino of any flavour through…

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The Nucleus Resolved, Ch Stellar burning and the origin of the elements

Problem

(a) A heavy-water detector registers a neutrino of any flavour through neutral-current breakup of the deuteron, which needs a neutrino energy above the deuteron's binding energy,

2.22\,\mathrm{MeV}

. Using the branch ranges pp continuum (endpoint

0.42\,\mathrm{MeV}

), the

^7\mathrm{Be}

lines (

0.862

and

0.384\,\mathrm{MeV}

) and the

^8\mathrm{B}

continuum (endpoint about

15\,\mathrm{MeV}

), state which branch or branches such a detector can register. (b) In a neutron bath at r-process conditions, the path reaches the

N=50

shell closure at

Z=30

(zinc),

A=80

, and waits there for beta decay. The stable nucleus that anchors the valley of stability at

N=50

^{88}\mathrm{Sr}

(

Z=38

). Beta decay at constant mass number carries the waiting-point chain to the first stable isobar near

A=80

. State the mass-number displacement between this r-process peak and the

N=50

s-process peak, and say whether it falls inside the usual range of eight to thirteen mass units. (c) On the solar-system abundance curve, the sawtooth pattern running from carbon to calcium and the smooth fall toward the actinides are two separate features. Assign each to the process responsible, and give the one nuclear fact behind each.

Related theory

Nuclear Physics

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