Fill in the missing parn *or)6rkajj 4f*qkqeyf8v )w o:;/hnticles or nuclei:
(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 producing nuclear react.hz mnq .sf8fjl 67ld:g2 1s+q 2tl,xud;jyf kions?

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 f+2jqi(x*wr0snj*8kk6uu p*x b k sp9$\beta^+$ 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 o)7t;e*iuirdj n*yq /dps53jkf thermal energy - but the tp7 *tj i)yqisk3nrd5euj*; /d hermal energy of what?

The energy from nuclear fission(kh4wdacj1vt,p-o *p *i m7eqkr ig4. appears in the form of thermal energy - but the thermal voa ,eg i* 4.q1p (t hrkjw-cdmp*7ik4energy of what?

Why can't uranium be enriched by chemp/ ry fnu/(h*cl)ql(c ical means?

How can a neutron, with prac.u* 8t1irmd0jq k 1ynytically no kinetic energy, excite a nucleus to the extent shown in (Fig. Belyn*8rt dk yum01i1 j.qow)?

Why would a porous block of uranium be more likely to explode if kept under wao+qy 1,j vqi*gter rather than+qj1qyv * iog, in air?

A reactor that uses highly enriched uranium can ,a-u euk0l ;7y5:yr+qyb 5igdyoc k-juse ordinary water (instead of heavy water) as a moderator and still have a self-susti0kyj55yu; aqb l,: r--dyce+k7 u goyaining chain reaction. Explain.

Why must the fission process release neutrons if it is to be use( x(cb//r ypq6g9tui kful?

Discuss the relative merits and disadvantages, including z v ztakg0+8 rvx(eh-.pollution and safety, of power generaxvz- a +vr.ez( tkg0h8tion by fossil fuels, nuclear fission, and nuclear fusion.

What is the reason for the "secondary system" in a nuclear reactor,jk* qnxh-1u5 - ymhgd3 (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor not used directly t- -135gjqduh xykmn*ho drive the turbines?

Why are neutrons released in a fission reactionw f)neb+s-g5x?

Why do gamma particles p9vkucp3x8jnysf s/ .8enetrate matter more easily than beta particles do?

A higher temperature is required for deuterium-deun-7lysplz3 s .terium ignition than for deuterium-triti.ss y z7-l3nlpum. Explain.

Light energy emitted by the Sun and *7b+7d: ux s6q+xs wgjj; yvjostars comes from the fusion process. What conditions in the interior of stars yd;uj7: w7gxj +xqj+* ovb6ssmake this possible?

How do stars, and our Sun, mt0dp1vxytw58iccj7- aintain confinement of the plasma for fusion?

What is the basic difference bete3*w2:nov f jhween fission and fusion?

People who work around metals that emit alpha parncw-otna h3 f0: kw;6yticles are trained that there is little danger from proximity or even touching the material, but that they must take extr f 3t6y;0-wn:nahkow ceme precautions against ingesting it. Hence, there are strong rules against eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation 79n,i+eh:bhjq i qc: kdose higher for women beyond the child-bearing age than f,qq9hc b: j:inie+h k7or younger women?

Radiation is sometimes used to sterilize me0zn:xl d8cdj(frz11zv2 ja 1wn7)axsdical supplies and even food. Explain how it work)cnxalw8v (js2z jd1f xd:17n1r0a zzs.

What is the difference between a *ii9v )y.;0ob6(kcik cnwkhbjyx d9+bsorbed dose and effective dose? What are the SI units for each(+k)kc9j xi dw*;bon iv90c h6y.kyi b?

How might radioactive tracer 8g5zn5xi3 d pyy:d/eks be used to find a leak in a pipe?

Natural aluminum is all q xd4d .1q5+n:+qkrk9wcn m3d y +wphq$_{13}^{27}\text{Al}$. 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 reacb,m/azcnl. ,mtion $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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) fo y3fst p,fl*/hr the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction 1tw g7uo+z *hi$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reactionp6 .wm64ka w1wgc. rtc $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 "captu* t 0)hg/we3 yxptzk7hre" reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$.Q =    MeV

  Calculate the total kinetic energo yz,f/+2vx rwm7v4ppf7* ls9 .q icqfy of the products 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 reaction t4es c93gjhaxd9yc7 ac,w:bk a/x 6n1is $\text{d} + _{3}^{7}\text{Li} \to \text{X} + \text{p}$.
(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" nuclear reac :(pq-2dxelngtion 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 nuclearblkcx r;:u,6u 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 energy released in the fission reaction kcuve4v ,pclo8bjg 4wfn -*5 9$_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. 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 oao q4a (o 6tipk53dv:uf Eq. 31-4? (The masses of 354: dv aaukq (ootpi6$_{56}^{140}\text{Ba}$ 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 przm4* rkd,m+200-MW reactor? Assume 200 MeV is released per fissiod,r+kp4zm rm* n. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is about 200 a;xoet) yq9a :MeV per fission. What fraction of the rest mass o e 9aqxo)t;ay:f a $_{92}^{235}\text{U}$ nucleus is this?$\approx1/$   

  Consider the fission rea4yssuq+,)o my ction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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, in3mupz h nw+mu w0):c8f a typical house ium3p) wm f nh0+w8zcu:s 950 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 ofe fh9)qz ou 47(cqgu0y $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency.$\approx $    $\ \text{kg U}$

  Assuming a fission of ae0 v-lwtjkm w.z5:xua)wy27 $_{92}^{235}\text{U}$ 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 pra cip 2r8x0h uiy rvu9rg)g8 .m09e m+rkb,v0kotons at the center of a star where the temperature is 0gruie k8ak)v by8mu2ch+.m9rrrvxp , 90gi0 $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

Show that the energy released in the fusion react6:oyb qt+q(4 xz9nuu xm(bwz/ ion $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is 17.59 MeV.

Show that the energy reg( 2;h,vq 8zrm-j f xz;fz/nzcleased when two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is 3.27 MeV.

  Verify the Q-value stated for each of the reactions ofEqs. 6. [Hint: Be careful with electrons.]

6-b Q =    MeV
6-C Q =    MeV

  Calculate the energy release per gram of fuel for the reactions of Eqs. 8a, b, 6y ee+.+vj . h:szbzxoand c. Compare to the.zyx6ej.:bzs+ o+e v h energy release per gram of uranium in fission.
8a =    $ \times 10^{23}\ \text{MeV/g}$
8b =    $\times 10^{23}\ \text{MeV/g}$
8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is released wheix67vh z(xk*ube )/t sn $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house rdm,xnlk: 2vs z(pk v50equires 950 W of electric power on average, what minimum amount of deuterium fuel would han2xm0 s, vv: (pdzkk5lve to be used in a year to supply these electrical needs? Assume the reaction of Eq. 8b.    g

Show that the energies carried offm+sovxlk )m+ wzn.3r 8 by the $_{2}^{4}\text{He}$ nucleus and the neutron for the reaction of Eq. 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-d" reactions, Eqs. 88. j.pn*rbv0k cqyw/f9 nmb 8bf b,;kpa and b. Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reactor, assuming 30% effk0k*n8 jfv;ymp nb.bc/bf .,qrb8p 9wiciency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00x3 )q e;,3--t/vfntv obkyrnv kg of water if its natural deuterium is used in the fusion reaction of Eq. 31-8a? Compare to the energy obtqk /b n;xt-tf3-)v,ev3oyvr nained from the burning 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 i r (qihb7i5/q6y6p )rf3hap)a,zpci believed to be due to the 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 pi5f6crbqh/z)h ), 6ayp3iaqip(ir 7cycle. (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 reacds-,.9olnw iw tion of the carbon cycle to that for a deuterium-trit swo,9-nl dw.iium 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 bu 6ciiz8.p96bm k, wb$\gamma$ 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 biological damage as 75 rads o m,wt)q/ythr0f fast), /qthtmw yr0 neutrons?    rad slow neutrons

  How much energy is deposited in the body on4bk1kv*: if9(ptn fgczu e ,4f a 65-kg adult exposed to a 2.0-Gy do nfz:vgu4 4*b1ftk pi(,9nkec se?    $J$

  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 which protons 9iq0q; plwjy1 with an energy of 1.2 MeV are incident o yl1wq9p jqi;0n 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 od 3-w 1rmkz2j$_{15}^{32}\text{P}$ (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 f(6hxt c4yx;a this is consistent with the two definitions of th tay xcfx64;(he 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 a 0sg* wo a3n t9c77v 1gjbrdj1nxczt,*$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactivc.0hjzn20cp(mz ;yffe $_{53}^{131}\text{I}$ 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 acte2j csuat v2 z21;lp8oivity of 2000 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 wavelength of photon 2dqnt;i(vin +s needed to produce NMR transitions in free protons in a 1.i ti( vnn2;d+q000-T field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombarwsedcs+1 tvh 3/.rc, l(ypi(sding $_{4}^{9}\text{Be}$ 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 g-fdeje1pp b8()x i9cconversion factor from kelvins to keV8f9(1depcx- ji)p be g 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 uranium isa-nxj a:nbm9ee,e +;g0h4qf w 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 av6(d4cg)h wlbwerage yearly background radiation consists of 21 mrad of X-rays andcb6 hdw)gw4(l $\gamma$ 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 on averajx9b /./76)/ mnlrqzkvmwthpge. Make a rough estimate of tv/xlbw7p n9)mhz /q/ tk.j6rmhe total deuterium in the Earth's oceans and estimate the total energy released if all of it were used in fusion reactors.
$\approx $    $ \times 10^{15}\ \text{d atoms}$
$\approx$    $ \times 10^{16}\ \text{kg d}$
   $\times 10^{30}\ \text{J}$

  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 that plry pc ,q10ma4 z99bwproduce 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 the Sun, fkomr-3ewl r4+sl-k5 the neutrinos escape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2 MeV, is available within k rwf l3morls k-e5-+4the 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 rato 5vtw.9iv /ace 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. 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 ev2+zq; w -w , r7gpbnespkc(7fcks7cb7olution, may begin to 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 contains abo4m)s k1,yar5wj7 k0 oc2r ln3 jlq5xreut $0.10\ \mu\text{Ci}$ 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 occuaq( 3va iw3w zll bm42:o6elh)rred 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 c4bd:16oief :padmi6 r an 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 activity, 25 mCi. Sourye0 /o l0srfffx**mbs3 ( zd2x6qg.k fce A emits 1.0-MeV 2 * f .zs(y0f*xml fde6 fqorxg3b0k/s$\gamma$ 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 the ingestion9puqiopl9ic 2. tu9k* 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 $    $\ \text{mCi}$