Quantum Physics

Problems 1005particles fuse to produce a nucleus A and a gammaray. What is nucleus A? (b) Nucleus A absorbs an alphaparticle to produce a nucleus B and a gammaray. What is nucleus B? (c) Find the total energy releasedin the reactions given in (a) and (b). [Note :8The mass of Be 8.005 305 u.]412. Another series of nuclear reactions that can produceenergy in the interior of stars is the cycle describedbelow. This cycle is most efficient when thecentral temperature in a star is above 1.6 10 7 K.Because the temperature at the center of the Sun isonly 1.5 10 7 K, the following cycle produces lessthan 10% of the Sun’s energy. (a) A high-energyproton is absorbed by 12 C. Another nucleus, A, isproduced in the reaction, along with a gamma ray.Identify nucleus A. (b) Nucleus A decays throughpositron emission to form nucleus B. Identify nucleusB. (c) Nucleus B absorbs a proton to produce nucleusC and a gamma ray. Identify nucleus C.(d) Nucleus C absorbs a proton to produce nucleusD and a gamma ray. Identify nucleus D. (e) NucleusD decays through positron emission to produce nucleusE. Identify nucleus E. (f) Nucleus E absorbs aproton to produce nucleus F plus an alpha particle.What is nucleus F ? [Note : If nucleus F is not 12 C—that is, the nucleus you started with—you havemade an error and should review the sequence ofevents.]13. If an all-electric home uses approximately2 000 kWh of electric energy per month, how manyfusion events described by the reaction21 H 3 1 H : 4 2 He 1 0 n would be required to keepthis home running for one year?14. To understand why plasma containment is necessary,consider the rate at which an unconfinedplasma would be lost. (a) Estimate the rms speed ofdeuterons in a plasma at 4.00 10 8 K. (b) Estimatethe order of magnitude of the time such a plasmawould remain in a 10-cm cube if no steps weretaken to contain it.15. The oceans have a volume of 317 million cubic milesand contain 1.32 10 21 kg of water. Of all the hydrogennuclei in this water, 0.030 0% of the mass isdeuterium. (a) If all of these deuterium nucleiwere fused to helium via the first reaction in Equation30.4, determine the total amount of energythat could be released. (b) The present world electricpower consumption is about 7.00 10 12 W.If consumption were 100 times greater, howmany years would the energy supply calculated inpart (a) last?Section 30.6 Positrons and OtherAntiparticles16. Two photons are produced when a proton and anantiproton annihilate each other. What is the minimumfrequency and corresponding wavelength ofeach photon?17.A photon produces a proton–antiproton pair according to the reaction. What is the minimum possible frequencyof the photon? What is its wavelength?18. A photon with an energy of 2.09 GeV creates aproton–antiproton pair in which the proton has akinetic energy of 95.0 MeV. What is the kinetic energyof the antiproton?Section 30.7 Mesons and the Beginning of ParticlePhysics19. When a high-energy proton or pion traveling nearthe speed of light collides with a nucleus, it travelsan average distance of 3.0 10 15 m before interactingwith another particle. From this information,estimate the time for the strong interaction tooccur.20. : p pCalculate the order of magnitude of the range of theforce that might be produced by the virtual exchangeof a proton.21. One of the mediators of the weak interaction is theZ 0 boson, which has a mass of 96 GeV/c 2 . Use thisinformation to find an approximate value for therange of the weak interaction.22. If a 0 at rest decays into two ’s, what is the energyof each of the ’s?Section 30.9 Conservation LawsSection 30.10 Strange Particles andStrangeness23. Each of the following reactions is forbidden. Determinea conservation law that is violated for eachreaction.(a) p p : e (b) p : p (c) p p : p (d) p p : p p n(e) p : n 0