Fill in the missing particles or o;r6ipg4:edby:i(ebnuclei:
(a) $\text{n} + _{56}^{137}\text{Ba} \to ? + \gamma$
(b) $\text{n} + _{55}^{137}\text{Cs} \to _{56}^{137}\text{Ba} + 2?$
(c) $_{92}^{235}\text{U} + \text{n} \to _{38}^{90}\text{Sr} + ? + 3\text{n}$
(d) $? + \text{d} \to _{79}^{197}\text{Au} + \alpha$
where d stands for deuterium ($_{1}^{2}\text{H}$).

The isotope $_{15}^{32}\text{P}$ is produced by the reaction: $? + \text{n} \to _{15}^{32}\text{P} + \text{p}$. What must be the target nucleus?

When $_{11}^{22}\text{Na}$ is bombarded by deuterons ($_{1}^{2}\text{H}$), an $\alpha$ particle is emitted. What is the resulting nuclide?

Why are neutrons such good projectiles for produq u vi f(/od3p7o9vy,pcing nuclear reactions?

A proton strikes a $_{10}^{20}\text{Ne}$ nucleus, and an $\alpha$ particle is observed to emerge. What is the residual nucleus? Write down the reaction equation.

Are fission fragments s7e)g4 1/mvqkiu,tkj $\beta^+$ or $\beta^-$ emitters? Explain.

  If $_{92}^{235}\text{U}$ released only 1.5 neutrons per fission on the average, would a chain reaction be possible?  ----待选择----yesno 
If so, what would be different?

$_{94}^{238}\text{Pu}$ releases an average of 2.5 neutrons per fission compared to 2.9 for $_{94}^{239}\text{Pu}$. Pure samples of which of these two nuclei do you think would have the smaller critical mass? Explain.

The energy from nuclear fma(ag(ohu9so 2ueizok5pi 0(5mr1d 1pb0s*sission appears in the form of thermal energy - but the thermal energy of wos m i uhgomui 00(z prk5*5sed a1poa92b((1shat?

The energy from nuclear fission appears in the form of thermas,+ hsfl6 mtom8b9q p9l energy - but the thermal energy offlop6m 89th q+ ,smbs9 what?

Why can't uranium be enriched by chemie 0jrnxap9-:.izer )rcal means?

How can a neutron, with practically no kinetic energy, excite a nucleus to t5o7 p fwa g*vdg3cd9,/: comknhsp5o 0he extent shown in (Fig. Below)hoo v/ao3 :cp kdwf,d7 5* pn5g9m0gcs?

Why would a porous block of uranium bgw)n9r13tzth7wc 9 j pe more likely to explode if kept under water rattg1 ct97wjrwn9 p3)zhher than in air?

A reactor that uses highzmdnfexn9j */bng 6as9 +v.x5 nz6s.bly enriched uranium can use ordinary water (instead of heavy water) as a moderator and still have a self-sustaining chaibjsnf.9*x5desz v a9/+znnm.xb6 n6gn reaction. Explain.

Why must the fission process release neutrons ifg(g jy8nr5.it5 2+ dz0iu vagk it is to be useful?

Discuss the relative merits and disadvantages, including p/7 rh(eg. /kwtq1 arvmnt1am 3ollution and safety, of power generation by fossil fuels, nuclear fission, a3hn7atr kg1tw(ae/ 1vm/ mq .rnd nuclear fusion.

What is the reason for the "secondary system" in a nucl3s1ar2m: nqjg ;k 1 8ddk+zukjear reactor, (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor n1jd28rjs; qkd1m kz 3gkuna :+ot used directly to drive the turbines?

Why are neutrons released in a fission rylvx.4*8xv5t 0p6xdco / frxreaction?

Why do gamma particles piu d+:tu-kq8r.bhk3vc o3 x:tenetrate matter more easily than beta particles do?

A higher temperature is required for deuterium-deute5 becps7vn8 nk0p54dnce.x6 evu,v1c rium ignition than for deuterium-tritium. nvv5np5ps41 x.0,d kee b78e v6uncccExplain.

Light energy emitted by the Sun and stars comes from the 9x4xvu kxo;h-fusion process. What conditions in the interior of starsu ;9xx4vk -xoh make this possible?

How do stars, and our Sun, maintain confinement ofa8 ,z (yuk0x 1qxas(qu3,rps q the plasma for fusion?

What is the basic difference between0bld0 4w2m7ewj3kp0 6bc2eb;fv nh u b fission and fusion?

People who work around metals that emit alpha particles are trained that ther5o)+udeklosua4v6n 6qh()c e e is little danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, there are strong rules against eating and drinking while working, and against machining the mcnos+66 kh4) de) (evqluoa5 uetal. Why?

Why is the recommended maximum radi ojnuxpqic f7++g k;5:ation dose higher for women beyond the child-bearing age thano ; g:q+pu5ik+ njxf7c for younger women?

Radiation is sometimes used to sterilize medic )jz jpht(m6 x(,yi2vkp;k 3ptal supplies and even food. Explain how it worpk (k6pji (2t,;mpjz xvt3hy)ks.

What is the difference between absorbed dose and eff,ub-ktk- 7hr.o* 4-xzk uur yzective dose? What are the SIu-7txo,urkh.kub* z-k- 4r yz units for each?

How might radioactive tracers nvt glcd+t21:be used to find a leak in a pipe?

Natural aluminum is all d-1hofs. zfbgh)s q- 1$_{13}^{27}\text{Al}$. If it absorbs a neutron, what does it become? Does it decay by $\beta^-$ or $\beta^+$? What will be the product nucleus?

Determine whether the reacti)b chr.. x2g2ci,c xc/uswv.ton $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ requires a threshold energy.

Is the reaction $\text{n} + _{92}^{238}\text{U} \to _{92}^{239}\text{U} + \gamma$ possible with slow neutrons? Explain.

  Does the reaction $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ require energy, or does it release energy? How much energy?    MeV

  Calculate the energy released (or energy input required) for t1 6muj1 6.x tt-ftjd3q sy/hwm/o)jldhe reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction lr8hu6:(wy,6oe 6xg m gcy3us$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ occur if the bombarding particles have 10.00 MeV of kinetic energy? (d stands for deuterium, $_{1}^{2}\text{H}$)
(b) If so, how much energy is released?    MeV

  (a) Can the reaction;u)-y;rxm sg6 hpv0fw $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ occur if the incident proton has kinetic energy = 2500 keV?
(b) If so, what is the total kinetic energy of the products?    MeV

  In the reaction $_{8}^{18}\text{O} + \text{p} \to _{9}^{18}\text{F} + \gamma$, the incident $\alpha$ particles have 7.68 MeV of kinetic energy.
(a) Can this reaction occur?
(b) If so, what is the total kinetic energy of the products? The mass of $_{9}^{18}\text{F}$ is 16.999131 u.   MeV

  Calculate the Q-value for the "cap 3nmy ;d o5/y *eh 6og*p8vi/bwuo2cemv00i juture" reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of the products nqzv*m0k w.ib+ (fjrbkwwm p 6* vb 2*8zmzt)-of the reaction $_{6}^{12}\text{C} + \text{d} \to _{7}^{13}\text{N} + \text{p}$ if the incoming deuteron (d) has $KE = 36.3\ \text{MeV}$. $KE_{\text{total}}$ =    MeV

  Radioactive $_{6}^{14}\text{C}$ is produced in the atmosphere when a neutron is absorbed by $_{7}^{14}\text{N}$. Write the reaction and find its Q-value. Q =    MeV

  An example of a "stripping" nuclear reacti3zx ij ,ixxgcjb*v 43+on is $\text{d} + _{3}^{7}\text{Li} \to \text{X} + \text{p}$.
(a) What is X, the resulting nucleus?
(b) Why is it called a "stripping" reaction?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic? Q =    MeV

  An example of a "pick-up"ag ur *;o1c475f trlaf nuclear reaction is $_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(a) Why is it called a "pickup" reaction?
(b) What is the resulting nucleus?
(c) What is the Q-value of this reaction? Is the reaction endothermic or exothermic?Q =    MeV

  (a) Complete the followi8e/z;buzd( rqng nuclear reaction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(b) What is the Q-value? Q =    MeV

  The reaction $_{9}^{19}\text{F} + \text{n} \to _{9}^{20}\text{F} + \gamma$ requires an input of energy equal to 2.453 MeV. What is the mass of $_{9}^{20}\text{F}$?
$m_{^{18}_{9}F}$ =    U

  Calculate the energyoavzoxidsn+ k i/1v)e6rk )9 n1 p06dy released in the fission reaction $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy released in the fission reaction of Eq. 31-4? (The mass,rsnhw n99c.9qto3edes of h 3cwrts9eon99 n,.q d$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per second in a 200-MW reactor? Assume 200 MeV i7f9y rk7g/egy s rg79f gy k/ry7eeleased per fission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is abovts-x swk)v;0/qv ke 9ut 200 MeV per fission. What fraction of the0/q-evx)v s ;tvskwk9 rest mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission f 2oev h)*p(cnizq(oqmftv 5a u6w n)pm *1l.2reaction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(a) How many neutrons are produced in this reaction?   
(b) Calculate the energy release. The atomic masses for Sb and Nb isotopes are 132.915250 u and 97.910328 u, respectively. Q =    MeV

  How much mass of $_{92}^{235}\text{U}$ is required to produce the same amount of energy as burning 1.0 kg of coal (about $3 \times 10^7\ \text{J}$)?    $ \times 10^{-7}\ \text{kg}$

  Suppose that the electric average power consumption, day and night, i.5:.kmlixvq uen*zb sj( /,gg n a typical house is 950 W. What initial mass of m lzsx *(n.ek iugb qjg,/:v5.$_{92}^{235}\text{U}$ would have to undergo fission to supply the electrical needs of such a house for a year? (Assume 200 MeV is released per fission, as well as 100% efficiency.)    $ \times 10^{-4}\ \text{kg}$

  What initial mass ofj iip*7ne 7 rvn+lq(v:v2(hgo $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission of 5xc1dco9b)frdwv 97 wt0 zl:2vsd ep8 $_{92}^{235}\text{U}$ into two roughly equal fragments, estimate the electric potential energy just as the fragments separate from each other. Assume that the fragments are spherical (see Eq. 30-1) and compare your calculation to the nuclear fission energy released, about 200 MeV.
PE =    MeV
This is about    % larger than the nuclear fission energy released.

  What is the average kinetic energy of protons at the+xbg 5kp8 b1agxw -4d7d3 daab center of a star where the temp+apbd dx5k3 gdxag87-a1b4wberature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released in the fusion reactip*) tm0p u2x fyh8fi:kon $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released when two deuterium nucleif:4x 8 0v hwxf w6eqr0dy60ait fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for each of the reactions ofEqs. 31u m:kfn( l1hnix v4y0;;n j2sk3dmpy0-6.
Eqs. 31-6-a Q =    MeV
Eqs. 31-6-b Q =    MeV
Eqs. 31-6-c Q =    MeV

  Calculate the energy release per gram of fuel for the a3j 1e4ex9cilreactions of Eqs. 31-8a, b, and c. Compare to the energy release per gl9ca13x4 ji eeram of uranium in fission.
31-8a =    $ \times 10^{23}\ \text{MeV/g}$
31-8b =    $\times 10^{23}\ \text{MeV/g}$
31-8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is releaseddpi(5lc: 0 idp when $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of electric power on average, what minimu-rm gm99st/ij/ ckh *lm amount of deuterium fuel would have to be used in a year to supply these electrical needs? Assumeh jclt/kmr*9sg 9-m /i the reaction of Eq.31- 8b.    g

Show that the energies car)3 z:t:bwv a ,(qrenc+)sahzfried off by the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 31-8c are about 3.5 MeV and 14 MeV, respectively. Are these fixed values, independent of the plasma temperature?

  Suppose a fusion reactor r)v7/czfs4 m snan on "d-d" reactions, Eqs. 31-8a and b. Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reactor, asm) s74nvz cs/fsuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is containnf/k)z2 op.awvg.2j*z l nzwbs t;91med in 1.00 kg of water if its natural deuterium is used in the fusion reaction of Eq. 31-8a? Compare to the energy obtained from the burninb1 nw9af 2 *nvmpzo/kszw.;jzlt2. )gg of 1.0 kg of gasoline, about $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massive stars is believed to be due to the8i iy*l7muvr3 carbon cycle (see text). (a) Show that no carbon is consumed in this cycle and that the net effect is the same as for the proton-proton cycle. (b) What is the total energy release? (c) Determine the energy output for each reacti*yu3 vli7 rm8ion and decay. (d) Why does the carbon cycle require a higher temperature ($T \approx 2 \times 10^7\ \text{K}$) than the proton-proton cycle ($T \approx 1.5 \times 10^7\ \text{K}$)?

(a) Compare the energy needed for the first re 8c1q wqv::kvxaction of the carbon cycle to that for a deqcxv: v k8:q1wuterium-tritium reaction.
(b) If a deuterium–tritium reaction requires $T \approx 3 \times 10^8\ \text{K}$, estimate the temperature needed for the first carbon-cycle reaction.

  A dose of 4.0 Sv of 8r ob7wkr 6i2j,4hpzs 0vlg/j$\gamma$ rays in a short period would be lethal to about half the people subjected to it. How many grays is this?    $Gy$

  Fifty rads of $\alpha$-particle radiation is equivalent to how many rads of X-rays in terms of biological damage?    rad

  How many rads of slow neutrons will do as much biologicalrl +xa v:iow9;tbga95 damage as 75 rads of fast neutr +vi9 ob;lat 5gra:xw9ons?    rad slow neutrons

  How much energy is deposited in the body of a 65-kg adult exposed to a 2.0-Gy dood3 fi*fwyk:2y 5j5zbskb5z5jw 3 i:o*yf fd2ye?    $J$

  A $0.025-\mu\text{Ci}$ sample of $_{15}^{32}\text{P}$ is injected into an animal for tracer studies. If a Geiger counter intercepts 25% of the emitted $\beta^-$ particles, what will be the counting rate, assumed 85% efficient?$\approx$    $ \ \text{counts/s}$

  A cancer patient is undergoingw eksf /zqe/2hoczl *2(hlt45 zvi3l, radiation therapy in which protons with an energy of 1.2 MeV av3h/ql 2 (cw/fs* 5etiekzz,2 ohzl4lre incident on a 0.25-kg tumor.
(a) If the patient receives an effective dose of 1.0 rem, what is the absorbed dose?
(b) How many protons are absorbed by the tumor? Assume $QF = 1$.    $ \times 10^{10}\ \text{p}$

  A 1.0-mCi source of *6ay kl0kqp h,$_{15}^{32}\text{P}$ (in $\text{NaHPO}_4$), a $\beta^-$ emitter, is implanted in a tumor where it is to administer 36 Gy. The half-life of $_{15}^{32}\text{P}$ is 14.3 days, and 1 mCi delivers about $10\ \text{mGy/min}$. Approximately how long should the source remain implanted?    day

About 35 eV is required to produce one ion pair in air. Show that this,lv-9 jk;udsv is consistent with th- j v9lv;k,dsue two definitions of the roentgen given in the text.

  $_{27}^{57}\text{Co}$ emits 122-keV $\gamma$ rays. If a 70-kg person swallowed $1.85\ \mu\text{Ci}$ of $_{27}^{57}\text{Co}$, what would be the dose rate (Gy/day) averaged over the whole body? Assume that 50% of the $\gamma$ energy is deposited in the body.    $\times 10^{-2}\ \text{Gy/day}$

  What is the mass of lftg 2j(8 b9kla $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactive gq6vrt : 0qq2c$_{53}^{131}\text{I}$ were released in the accident at Chernobyl in 1986. Chemically, iodine goes to the human thyroid. (Doctors can use it for diagnosis and treatment of thyroid problems.) In a normal thyroid, $_{53}^{131}\text{I}$ absorption can cause damage to the thyroid.
(a) Write down the reactions for the decay of $_{53}^{131}\text{I}$.
(b) Its half-life is 8.0 d; how long would it take for ingested $_{53}^{131}\text{I}$ to become 10% of the initial value? N $\approx$    $ \ \text{d}$
(c) Absorbing 1 mCi of $_{53}^{131}\text{I}$ can be harmful; what mass of iodine is this?   $ \times 10^{-12}\ \text{kg}$

  Assume a liter of milk typically has an activity of 2000 pCir5ys d x* /peb.u(u59 nzrkyk8 due to $_{19}^{40}\text{K}$. If a person drinks two glasses (0.5 L) per day, estimate the total effective dose (in Sv and in rem) received in a year. As a crude model, assume the milk stays in the stomach 12 hr and is then released. Assume also that very roughly 10% of the 1.5 MeV released per decay is absorbed by the body. Compare your result to the normal allowed dose of 100 mrem per year. Make your estimate for
(a) a 50-kg adult, $\approx$    $ \times 10^{-7}\ \text{Sv/year}$ $\approx $    $ \times 10^{-5}\ \text{rem/year}$ $\approx $    $ \times 10^{-4}$ times the allowed dose
(b) a 5-kg baby.   $\times 10^{-4}\ \text{Sv}$    $\times 10^{-4}\ \text{rem}$    $ \times 10^{-4}\ \text{times the allowed dose}$

Radon gas, $_{86}^{222}\text{Rn}$, is considered a serious health hazard (see discussion in text). It decays by $\alpha$ emission.
(a) What is the daughter nucleus?
(b) Is the daughter nucleus stable or radioactive? If the latter, how does it decay, and what is its half-life?
(c) Is the daughter nucleus also a noble gas, or is it chemically reacting?
(d) Suppose 1.0 ng of $_{86}^{222}\text{Rn}$ seeps into a basement. What will be its activity? If the basement is then sealed, what will be the activity 1 month later?

  Calculate the wavelength of photons nee** s606nu yyfwea.uusded to produce NMR transitions in free protons in a 1.suu6wneuaf.6 0 *ys* y000-T field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron : om7stdof9 m(by bombarding $_{4}^{9}\text{Be}$ with the popular projectile of the day, alpha particles.
(a) If one of the reaction products was the then unknown neutron, what was the other product?
(b) What is the Q-value of this reaction?Q =    MeV

  Fusion temperatures 30bv: s7ncjyh2ots i 7x8mme0 are often given in keV. Determine the conversion factor from kelvom0h 3v2js87s txc7: eminb0y ins to keV using, as is common in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching urani65z z .,(e uayxzrg 5rge/yli4ee 6-ddum is by diffusion of the gas $\text{UF}_6$. Calculate the ratio of the speeds of molecules of this gas containing $_{92}^{235}\text{U}$ and $_{92}^{238}\text{U}$ on which this process depends.    :1

  (a) What mass of $_{92}^{235}\text{U}$ was actually fissioned in the first atomic bomb, whose energy was the equivalent of about 20 kilotons of TNT (1 kiloton of TNT releases $5 \times 10^{12}\ \text{J}$)? $\approx $    $\ \text{kg}$
(b) What was the actual mass transformed to energy?$\approx $    $\ \text{g}$

  In a certain town the average yearly backgr xy3i ;aoc 4h-ux/m+mfound radiation consists of 21 mrad of Xx-ayx 3m o4fm/cu i+h;-rays and $\gamma$ rays plus 3.0 mrad of particles having a QF of 10. How many rem will a person receive per year on the average?dose(rem) =   $ \times 10^{-2}\ \text{rem/yr}$

  Deuterium makes up 0.0115a+ ; ub/* up0ln9vo2;gowlpno% of natural hydrogen on average. Make a rough estimate of the totlpp;w/oa 90ub *+;2oungol nv al deuterium in the Earth's oceans and estimate the total energy released if all of it were used in fusion reactors.

The total mass of deuterium is about    $ \times 10^{16}\ \text{kg}$
The total energy is about    $\times 10^{30}\ \text{J}$

  A shielded $\gamma$-ray source yields a dose rate of $0.052\ \text{rad/h}$ at a distance of 1.0 m for an average-sized person. If workers are allowed a maximum dose of 5.0 rem in 1 year, how close to the source may they operate, assuming a 40-h work week? Assume that the intensity of radiation falls off as the square of the distance. (It actually falls off more rapidly than $\frac{1}{r^2}$ because of absorption in the air, so your answer will give a better-than-permissible value.)    m

Radon gas, $_{86}^{222}\text{Rn}$, is formed by $\alpha$ decay. (a) Write the decay equation. (b) Ignoring the kinetic energy of the daughter nucleus (it's so massive), estimate the kinetic energy of the $\alpha$ particle produced. (c) Estimate the momentum of the alpha and of the daughter nucleus. (d) Estimate the kinetic energy of the daughter, and show that your approximation in (b) was valid.

  Consider a system of nucleaapg+l 7fq:* zpr power plants that produce 3400 MW.
(a) What total mass of $_{92}^{235}\text{U}$ fuel would be required to operate these plants for 1 yr, assuming that 200 MeV is released per fission? $\approx$    $ \ \text{kg}$
(b) Typically 6% of the $_{92}^{235}\text{U}$ nuclei that fission produce $_{38}^{90}\text{Sr}$, a $\beta^-$ emitter with a half-life of 29 yr. What is the total radioactivity of the $_{38}^{90}\text{Sr}$ in curies, produced in 1 yr? (Neglect the fact that some of it decays during the 1-yr period.) $\dfrac{\Delta N}{\Delta t}$    $ \times 10^{6}\ \text{Ci}$

  In the net reaction,, fora2t5 thh 8sdp+ the proton-proton cycle in the Sun, the neutrinos escape from the Sun with energy o+hp528 htad tsf about 0.5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this value to calculate the "heat of combustion" per kilogram of hydrogen fuel and compare it to the heat of combustion of coal, about $3 \times 10^7\ \text{J/kg}$.    $ \times 10^{-14}\ \text{J/g}$
This is about    $ \times 10^7$times the heat of combustion of coal.

  Energy reaches Earth from the Sun at a ratek30bqmadal6:k up5 )p of about $1400\ \text{W/m}^2$. Calculate
(a) the total power output of the Sun,$\approx $    $ \times 10^{26}\ \text{W}$
(b) the number of protons consumed per second in the reaction of Eq.31- 7, assuming that this is the source of all the Sun's energy. $\approx $    $ \times 10^8\ \text{protons/s}$
(c) Assuming that the Sun's mass of $2 \times 10^{30}\ \text{kg}$ was originally all protons and that all could be involved in nuclear reactions in the Sun's core, how long would you expect the Sun to "glow" at its present rate? See previous Problem.$ \approx $    $ \times 10^{11}\ \text{yr}$

  Some stars, in a later stage of evolution, may begin to fusk el2i9rocj:n20e0 hx w8 wz4ke two $_{6}^{12}\text{C}$ nuclei into one $_{12}^{24}\text{Mg}$ nucleus.
(a) How much energy would be released in such a reaction?
(b) What kinetic energy must two carbon nuclei each have when far apart, if they can then approach each other to within 6.0 fm, center-to-center? KE =    $ \times 10^{-13}$ =    MeV
(c) Approximately what temperature would this require?   $ \times 10^{10}\ \text{K}$

  An average adult body contains ab*brs/ f9emj8f6b 9ns54d rl ybout $0.10\ \mu\text{Ci}$ of $_{19}^{40}\text{K}$, which comes from food.
(a) How many decays occur per second?    $\ \text{decays/s}$
(b) The potassium decays produce beta particles with energies of around 1.4 MeV. Calculate the dose per year in sieverts for a 50-kg adult.    $\times 10^{-4}\ \text{Sv/y}$
Is this a significant fraction of the $3.6\ \text{mSv/year}$ background rate?    %

  When the nuclear reactor accident occuryooo0hdk 5 6vrk8 yy:+red at Chernobyl in 1986, $2.0 \times 10^7\ \text{Ci}$ were released into the atmosphere. Assuming that this radiation was distributed uniformly over the surface of the Earth, what was the activity per square meter? (The actual activity was not uniform; even within Europe wet areas received more radioactivity from rainfall). $\frac{\text{Activity}}{\text{m}^2}$=   $ \times 10^{3}\ \text{decays/s}$

  A star with a large helium abundance can burhr;i .p uwnj:9n helium in the reaction $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. What is the Q-value for this reaction? Q =    MeV

  A $1.0-\mu\text{Ci}\ _{55}^{137}\text{Cs}$ source is used for 2.0 hours by a 75-kg student in a physics lab. Radioactive $_{55}^{137}\text{Cs}$ decays by $\beta^-$ decay with a half-life of 30 years. The average energy of the emitted betas is about 190 keV per decay. The $\beta^-$ decay is quickly followed by a $\gamma$ ray with an energy of 660 keV. Assuming the student absorbs all emitted energy, what effective dose (in rem) is received during lab? dose $\approx $    $ \times 10^{-5}\ \text{rem}$

  A large amount of $_{38}^{90}\text{Sr}$ was released during the Chernobyl nuclear reactor accident in 1986. The $_{38}^{90}\text{Sr}$ enters the body through the food chain. How long will it take for 90% of the $_{38}^{90}\text{Sr}$ released during the accident to decay? See Appendix B.$\approx $    y

Three radioactive sources have the same activity, 25 mCi. Sou6e p+ j79uopzirce A emits 1.0-MeVu6 +po7z pe9ij $\gamma$ rays, source B emits 2.0-MeV $\gamma$ rays, and source C emits 2.0-MeV alphas. What is the relative danger of these sources?

  A 70-kg patient is to be given a medical test involving zrkh19 fr2 p-1wv1ppkthe ingestion of $_{43}^{99\text{m}}\text{Tc}$ (Section 31-7) which decays by emitting a 140-keV gamma. The half-life for this decay is 6 hours. Assuming that about half the gamma photons exit the body without interacting with anything, what must be the initial activity of the Tc sample if the whole-body dose cannot exceed 50 mrem? Make the rough approximation that biological elimination of Tc can be ignored. Activity $\simeq $    $\ \text{mCi}$