Fill in the missing particles or ph;79 zbz-*mcd lz zjp0x;si3nuclei:
(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 pw;n06dle+ wk7mi 9wg mrojectiles for producing 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 zr z02o/ og*ma k4e*ju$\beta^+$ 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 fission appears in the form ofi+1 g.nmze2wvcv, 0 ee thermal energy - but the thermal energy of whe ce,ng wve+2zv.mi 10at?

The energy from nuclear fission appears in th9 c.w8 jwa1,+hxq(uwxivls9t e form of thermal energy - but the thermal energy of whah9al txs.xvw(1uc ,+qijw8 w9t?

Why can't uranium be enriczeyx w;c5(2c.t,a jqkhed by chemical means?

How can a neutron, with practically no kinetic energy, excite a nucleus to t9lpqvm p9ptzzndo79+ yk 9 l;e-w3 f0ahe extent shown in (Fig. Bp l9v + f-kp9d9;pleon0zzym7t 3waq9elow)?

Why would a porous block of uranium be more likely to explode if keh n7lcvqgy5*.b tso oksvl905 95z3wdpt under water rather than in air?q0l* t 59cbv3zv7.os k wd5h5oynl9sg

A reactor that uses highly enriched uranium8,qi2 zdf cfo; can use ordinary water (instead of heavy water) as a moderator and still hafdqz8,;if c2 ove a self-sustaining chain reaction. Explain.

Why must the fission process release neutrons 1kkio8rtaya:+g+/k vysy 9 l7if it is to be useful?

Discuss the relative merits and disadvantag.5uu 3w ,zpn+o hf snrf4g*do+es, including pollution and safety, of power generation by fossil fuels, nuclear fission, and nuu o*fud +n,fozgn.r+ p sh34w5clear fusion.

What is the reason for the "secondary sysb8us 2t 34 faugx+mw1ztem" in a nuclear reactor, (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor not used directly to drive tb+wu utfm az3s18x 24ghe turbines?

Why are neutrons released in a 7ynxf -f6fuj5r m :av*nq5z ipsu0u+4 fission reaction?

Why do gamma particles penetrate matter more easily than beta particles d8, :chyiw6 /zm hq z;kg1fqx5uo?

A higher temperature is required for deuter bcgx 67ep(sq9ium-deuterium ignition than for deuterium-tqc7pbxs9g 6e(ritium. Explain.

Light energy emitted by the Sicr+(rwgu269 s t/ 8q 3q .rdyjpghe/lvvhd 54un and stars comes from the fusion process. What conditions in the interior of stars make this possiblghh(6d/e/2wqj9qrid. + t v pc483ygr5s l rvue?

How do stars, and our Sun, maintain confinement of t9o*jtm lo2+ kghe plasma for fusion?

What is the basic difference between fission and fu k5pc1jck1hq8s+dl:t sion?

People who work around metals that emit alpha particles art58ulx 6vi xs.e trained that there 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 wor su lxx.vi865tking, and against machining the metal. Why?

Why is the recommended maximum h;yp lpj32w6sda- q 79c vnlr:radiation dose higher for women beyond the child-bearing ageh7qjc;yl69 d:awn2 vpr3 -psl than for younger women?

Radiation is sometimes8-5fruc 5eu.x9qydio used to sterilize medical supplies and even food. Explain how it works uf-5 oqrdyei 85uxc.9.

What is the difference between absorbed dose and effective qnq)w ug8-j*e dose? What are the SI units for eaqn)ug8j-qe *wch?

How might radioactive tracers be used to find a leavrxucknm fnb* .2j 5dqj+ 0+e9k in a pipe?

Natural aluminum is alfm1+4imgf,mi7 i 7ihil $_{13}^{27}\text{Al}$. 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 re9,412 pis a+lqqsozrsaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 4 n6e+av8bezz required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction t ah6 cfpaep ;)zp +)9 3hik*jdm3roa,$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 .8p2 npabcl y3ucu( a($_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 "capture" reactqy4 v )sfvv,- i*viy* w*9i n3xj7x/4 ojsgzuzion $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of the products of suifl24;x6l x 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 rehdn1lce 8 j1to76a -jkaction 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" nubj2 4rriqz- x9clear 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 following nuclear re gi g.dzwh7 btdn a8,,)+7qrnuaction: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 energy released in the fis5g7 3:yrqx fkbvlpn,,sion 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 reactiomi 5afoq 1 ;,ori53c6n.yhygi n of Eq. 31-4? (The masses of gymh3f,5.;nyro6ii1q i o5 ac$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take pyw r hdiz* ipwjia2; eq +3i94ly*m30alace per second in a 200-MW reactor? Assume 200 MeV is released per fission. 4;y9zmiqjpiiiwe0a yha 2 *3*drw + 3lP =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is about 200 MeV per fission. What frach;f wx2y*jlc2 +h7vgction of the rest mass of a wh;fc v7lyg cj+*x2 h2$_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission rersse(el(-j :m2wgovrky4yhg 7( d ;v/ action $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 averagjvpiwpuig) r6v5l*3h)l h 3z.*g bp fgr)26l he power consumption, day and night, in a typical house is 950b w r5ii z)lg hf*)23g3l)uplhppvhg.v6j*6 r W. What initial mass of $_{92}^{235}\text{U}$ 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 ofwp0ldu87 l 9zpsd4i1(g 5t+9o2 if8 l udttble $_{92}^{235}\text{U}$ 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 t;cu2x rry-n+ cj f(wg-4e9 q t/hew7z$_{92}^{235}\text{U}$ 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 center of a star where the31wph9irz 7n/ :aklfi temperature wp7z 1n 9ril/k ifa3:his $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released in the fusion pwcl )g)er0:f9i6v qyreaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released when two deuterium kcq*z 90rpcn.t i9 zr zq6/xi7nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for ea920g+ bu qj o.quq3ofcch of the reactions ofEqs. 31-6.
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 fu(xc8ww +swwf/ p69mt9c.wtcx*y af w7el for the reactions of Eqs. 31-8a, b, and c. Compare to thfc(ac9f6m.tx 79 cyww+ wt 8/* wsxwwpe energy release per gram 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 released whe mux460k) u 10 6siaddsj8lv1x cvpw3vn $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of electric ponrabe;7n. cy *+tog*pwer on average, what minimum amount of deuterium fuel w .tc +gr;b en*oypa7n*ould have to be used in a year to supply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carried off by fvi8w m0 mm lvuk.*96qthe $_{2}^{4}\text{He}$ 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 ran on "d-ymrdm,fw 0 -zzkhf1 5,d" reactions, Eqs. 31-8a and b. Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reactor, a0,kr1z w- hy,mmfzdf5ssuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of wa rv ci7nh7*z8d9vca2wter if its natural deuterium is used in the fusion reaction of Eq. 31-8a? Compare to the energy obtained from the burning of 1.0 kg of gasoline, acc8v2vdw7 hr*iz7an 9 bout $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massive stars is6w7(j4qapnq)nav t -hd ; pz1s believed to be due to the carbon cycle (see text). (a) Show that no carbon is consumed in this cycle and that the net effec)as-hn vn t;w 4 dz67jp1a(pqqt is the same as for the proton-proton cycle. (b) What is the total energy release? (c) Determine the energy output for each reaction 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 reaction of th gg0i-i 15 ufr g- dx2tbees,l6t0+csbe carbon cycle to that for a deuterium-tritium reaction. f+5 ru1i0x-g bt6egdi-cbet,s2sg0l
(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 /hh bbb j1r7c2 9wix:bfl0ycjv*3 e r(x(y-tc$\gamma$ 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 zeraoa, bx:oz:07 zz2 do as much biological damage as 75 rads of fast neutronxo zabz2: o0aer 7:zz,s?    rad slow neutrons

  How much energy is deposited in the bvy6z h)md;f 6gody of a 65-kg adult exposed to a 2.0-Gy dose? mzg6h vf)6; dy   $J$

  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 undergoing radiation therapy in whin09of(d52hlh3 w ng il/r+i klch protons with an energy of 1.2 MeV are incident on a 0.25-kg tumorl lwidro nnk i/20fhlh(g9+53.
(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 t(7 hh/uwe v5o9/ nzjhd*m wg:$_{15}^{32}\text{P}$ (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 iswiji)h.1r f kxfa3l,8 consistent with the two definitions of the roentgen giv3iw,r8j iaf )f. khl1xen 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 ey2d3vur c4 ,sa $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactive4*xi ymqtfazi*w; xvfs q8eyns6 4- ,- $_{53}^{131}\text{I}$ 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 20 zqrs5 i/t1(dufy,9so00 pCi 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 wavelengthn;p /pf ja-ckqq0c5(f of photons needed to produce NMR transitions in free protons in kp(p;0jf ca q/5nc-qf a 1.000-T field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bo ez.cb+t3bty.8dv x(rmbarding $_{4}^{9}\text{Be}$ 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 are often given in keV. Determine the conversion factoe+q4xa 5*xrni9yis,b r from kelvins to keV using, as is common in this fieli4a*bx i,n +qx9eys5rd, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uranium is by diffuvi;ldqf9.*2 u1oh m d/ /ryyijsion 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 backgmnts8 x. c:p(eround radiation consists of 21 mrad of X-raecxs(pnm8 .t:ys 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 0.0115% of natural hydrogen z dn3ua3.5hm don average. Make a rough estimate of the total deuterium in the Earth's oceans and estimate the total energy released if all of it were used in fusion reactors..a 3nh53mzdd u

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 nuclear power plants thptfh, o)z/qk+w+ e 6joat 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,, for the proton-proton cycle in tkv2 et u,/x,0q a5:8ddpsg,p fc3ef)m+w fjm she Sun, the neutrinos escape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available within the Sun. Use this value dep0 8xjpdfg +v:s skm,tmw2c/,5)q3a,e f fu 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 rate ofdjmm9m, hp16f 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 tow pd+/ hxc w xan0x .z2 /:ympo+s,:jlo.z7pmu fuse 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 conl;yfu0apa r+97cmmx b q561xy tains about $0.10\ \mu\text{Ci}$ 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 occp;kfn0*(ggr azw.h- j-ds b v(urred 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 abundabqxgwmcm7)rgu * ly9l j2mw*k s*.8 +wnce can burn 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 a-npw 9w-t/pm octivity, 25 mCi. Source A emits 1.0-MeV 9n/p wo m--wtp$\gamma$ 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 medq;lg( 7iij2x+ifmo(x ical test involving the 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 $    $\ \text{mCi}$