Table of Isotopes (small nuclei) 9 17 F 18 F 19 F 20 F 21 F 22 F 23 - - PowerPoint PPT Presentation

On the production of energy and helium in low energy nuclear reactions

John C. Fisher

Carpinteria, CA

ACS, March 22, 2010

Table of Isotopes (small nuclei)

1n 1H 2H 3H 3He 4He 6He 8He 6Li 7Li 8Li 9Li 11Li 7Be 9Be 10Be 11Be 12Be 14Be 8B 10B 11B 12B 13B 14B 15B 17B 19B 9C 10C 11C 12C 13C 14C 15C 16C 17C 18C 19C 20C 22C 12N 13N 14N 15N 16N 17N 18N 19N 20N 21N 22N 23N 13O 14O 15O 16O 17O 18O 19O 20O 21O 22O 23O 24O 17F 18F 19F 20F 21F 22F 23F 24F 25F 26F 27F 29F 31F 4n 5H 10He 16Be 21B 26O

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 1 2 3 4 5 6 7 8 9

Neutron number Proton number

Table of Isotopes (including hypothetical neutron isotopes)

1n 1H 2H 3H 3He 4He 6He 8He 6Li 7Li 8Li 9Li 11Li 7Be 9Be 10Be 11Be 12Be 14Be 8B 10B 11B 12B 13B 14B 15B 17B 19B 9C 10C 11C 12C 13C 14C 15C 16C 17C 18C 19C 20C 22C 12N 13N 14N 15N 16N 17N 18N 19N 20N 21N 22N 23N 13O 14O 15O 16O 17O 18O 19O 20O 21O 22O 23O 24O 17F 18F 19F 20F 21F 22F 23F 24F 25F 26F 27F 29F 31F 4n 5n 6n 7n 8n 9n 10n 11n 12n 13n 14n 15n 16n 17n 18n 19n 20n 21n 22n

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 1 2 3 4 5 6 7 8 9

Neutron number Proton number

Full table of isotopes

Charged isotopes Neutron isotopes

50 100 150 20 40 60 80 100 120

Neutron number Proton number

Question: How could you detect neutron isotopes?

◮ From their decay and reaction products ◮ These depend on how strongly isotopes are bound ◮ We need a model

Liquid-drop model

◮ Suppose that neutrons in a neutron isotope are bound about

1/2 as strongly as they are in an ordinary charged isotope.

◮ The volumetric neutron isotope mass excess then would be

∆(An) ≈ 8.071A − 7A ≈ A

◮ We need also a surface energy proportional to A2/3.

◮ Hypothesize: A2/3.

◮ Now we have the hypothetical neutron isotope mass excess

∆(An) = A + A2/3

Neutron isotope detection by radioactive decay (exothermic ββα)

◮ 200n −

→ 196n + 4He

◮ 196n −

→ 192n + 4He

◮ 192n −

→ 188n + 4He

◮ And so on. A neutron isotope decays by emitting a series of

energetic alpha particles.

◮

Overall: 200n − → 50(4He)

◮ We can detect the alpha particles.

Alpha particle shower

Etch pits on a detector chip in air under a nickel cathode (Oriani)

The Oriani shower

◮ 63 pits ◮ about 200 alphas in full 4π shower ◮ about 800 neutrons in parent neutron isotope ◮ Consistent with decay mode ◮ Consistent with large neutron isotopes ◮ Consistent with helium production

Full table of isotopes

200 400 600 800 40 80 120

Neutron number

Neutron isotope detection by growth reactions

◮ Isotope growth (deuterium fuel) 2H + An

− → A+1n + 1H

2H + A+1n −

→ A+2n + 1H

2H + A+2n −

→ A+3n + 1H

2H + A+3n −

→ A+4n + 1H

◮ Neutron isotope growth is accompanied by emission of

energetic protons.

◮ Isotope decay also occurs A+4n −

→ An + 4He

◮ Overall (steady state)

4(2H) − → 4(1H) + 4He + 20MeV

Neutron isotope detection by lithium-6 reactions

Isotope growth

6Li + An

− → A+1n + 5Li

6Li + A+1n −

→ A+2n + 5Li

6Li + A+2n −

→ A+3n + 5Li

6Li + A+3n −

→ A+4n + 5Li Isotope decay

A+4n −

→ An + 4He Overall (steady state) 4(6Li) − → 4(5Li) + 4He − → 4(1H) + 5(4He) + 14MeV

Neutron isotope detection by lithium-7 reactions

Isotope growth

7Li + An

− → A+2n + 5Li

7H + A+2n −

→ A+4n + 5Li Isotope decay

A+4n −

→ An + 4He Overall (steady state) 2(7Li) − → 2(5Li) + 4He − → 2(1H) + 3(4He) + 7MeV

Some useful things to study

◮ Energetic protons and alphas

◮ Explore basic reactions

◮ Helium and heat

◮ Identify and quantify nuclear fuels

◮ Transmutation (more expensive)

◮ Confirm and extend reaction dynamics

Helium and heat

Steady state reactions for selected fuel isotopes

2H:

4(2H) − → 4(1H) + 4He + 20MeV

6Li:

4(6Li) − → 4(1H) + 5(4He) + 14MeV

7Li:

2(7Li) − → 2(1H) + 3(4He) + 7MeV

9Be:

4(9Be) − → 9(4He) + 23MeV

13C:

4(13C) − → 4(12C) + 4He + 9MeV

17O:

4(17O) − → 4(16O) + 4He + 12MeV

18O:

2(18O) − → 2(16O) + 4He + 5MeV

232Th:

Complex, ambiguous,

238U:

not worked out.

Comments on neutron isotopes

◮ For theoreticians

◮ Ordinary nuclear physics with more isotopes

◮ For experimenters

◮ Opportunity for fundamental research

◮ For entrepreneurs

◮ It’s risky to ignore lithium and beryllium and other fuels