Fill in the missing part,:om -h v0ku.e te5qkjicles 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 suc a 0yw,rgl.3)vm by4qkh good projectiles 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+t(8/7kuh c t(qjgypz $\beta^+$ 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 fissi - t 4)3d+ ywwgkeewrg91cy6hyors+0w on appears in the form of thermal energy - but the thermal energy of whwe6+r g o3k 1y-ctdwreygs0)y4+h9w wat?

The energy from nuclear fission appears in the form of therdx4, k1m( nxswk y7jlz+np e .+,a(x)9i krtijmal energy - but the th1wi+ 4ij nnk7t k+rxl xm )s(adzekjp(9 .,y,xermal energy of what?

Why can't uranium be enriched by chemicy:pbva 3) dcl7al means?

How can a neutron, with practi/rge+(zrknx rn/ 4yz3n av.w )cally no kinetic energy, excite a nucleus to the extent shown in (Fig. Br )k/4ynzgx wr/.(era3nz+vnelow)?

Why would a porous block of urxj -zx4ufv q4fbd ,ibbq7t+18 anium be more likely to explode if kept under water ux fbj84d74izq b,b1x vf+qt -rather than in air?

A reactor that uses highly enriched uranium can use ordinary watervq+0vif )e.jb (instead of heavy wa.+ ebifv0q)jv ter) as a moderator and still have a self-sustaining chain reaction. Explain.

Why must the fission process release neutrons if it is to bde;p18+7w z x7xgpai0wqg pm0vd.u6be useful?

Discuss the relative merits and disadvantages, including pollution zbm7s n;mb3bk5a8 ef:qrjg r7+6zfn1 and safety, of power generation by fossil f3be r+ 7n:bf7 a58ksgm; 6znmfq1 jbrzuels, nuclear fission, and nuclear fusion.

What is the reason for the "secondary system" in a nuclear rg kwckx*s2ouw8t1 4l*8lx 2lm euo/e(eactor, (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor not used di(lek ueu*8c *t84 sg xkl2wowo x21m/lrectly to drive the turbines?

Why are neutrons released in a fissioy48(h 8c mqxtan reaction?

Why do gamma particla-yorl w)x h*)es penetrate matter more easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignition than fo ap*.2pdcv k6gr deuterium-tritium. Expg p. d2cp*a6kvlain.

Light energy emitted by the Sun p(d.i8qu( ek9f,f cxzf mnt liebpe/377 ) wq(and stars comes from the fusion process. What conditiofk.3( x 8epw /liuz t(bd pi9qfcfem 7eq,)7n(ns in the interior of stars make this possible?

How do stars, and our Sun, x,p 3dx-v tk.d kxy:0,wlh;jimaintain confinement of the plasma for fusion?

What is the basic difference between fission an ;-ne):tod2t dj vd dggjotmr6w2m49- d fusion?

People who work arou7cogykdkvu.) (2f;cdno k 4e3 nd metals that emit alpha particles are trained that there is little danger from proximity or even touching the material, but that they must take extreme precautions againsck7dny3 o4kvo )ge;f2(kdc.ut 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 dose higher foruj,)3d*, ktyy(l b rsp women beyond the child-bearing age than for younger women?*,jtk3 ,rlyb) dus( py

Radiation is sometimes used to sterilize medical supplies and evz uwplzy e +j4nd/jci6- (e59 sura)s*en food. Explain how it works4sij n6-c5lsa(z/* 9zup +w)rujed ey.

What is the difference between absorbed dose and e17g1q d/ -cv7jy8co ut fod:spffective dose? What are the SI units fo18pd7dgv7-cy 1o j/t oqufc: sr each?

How might radioactive tracers be usedox4k vvq6 f0(oi7qf xko r9.p6gbb8d* to find a leak in a pipe?

Natural aluminum is all 5fe vc6ryfz ;fj+ku f2,ys 8kqv/-txlz6 5vc($_{13}^{27}\text{Al}$. 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 reactiona7*mc8 fs yqd5 $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 enermtql65h *,e w;bvsd: qgy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction f ;d2ubqgs4ne/k 7 y0j$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reactionr3ea-7kw dnk)v g9*d; r+sjrt $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 "cqpif;ven(-rh 4.wsc+apture" reaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energ/lg1etu7 t(zmy1ne n 8 e/zpl8y 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" nuclefv3dg o/8xy5ra f:jsx(q jk/1ar reaction 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" nuclear reaction is evt3(rd b *qkbr 7 ws1kahc3:8$_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(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 reactionxqo4/, dnctk-z;s )kk: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 releaseab70y;*(1dssfyz su+n- s syz d 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 re6s)3vm ra 4q(/zp8kqfe,to/d(n srvnleased in the fission reaction of Eq. 31-4? (The masses of /8aes 6tko f sv)dqrr,nqp(vnm z/3(4$_{56}^{140}\text{Ba}$ 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 6dr71zkr(uvc reactor? Assume 200 MeV is released per fission. r6c (rkuz17v dP =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by ash f:4 iuy+9- g;opcc9 we;2wyf psk+a fission reactor is about 200 MeV per fission. What fraction of the re+4w9wghyy pfscc9pkfieo; sa ;:+ u2-st mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fissionqq9r: )2sutoi 8ruuw5 reaction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 niyi4ho.vd.k r6z:j5y 1x:m lqrght, in a typical house is 95r.h: q. xro6jyvz54mkli 1y :d0 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 ofr4ncy3wi25k : ah43 kqjjc m /yigwt,3 $_{92}^{235}\text{U}$ 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 u au,+x7var8: (/ vf sfnggoewkqd5,t,t; rt/$_{92}^{235}\text{U}$ 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 enez b/p0wi lo:t3lst1r3l)j.bqrgy of protons at the center of a star where the tempes31 i qjtlw0ltb3/p.zblo) r :rature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released in the fusion reactio,tvqy+ yi9i i+n $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy releas 6ed1(mi3fscmed when two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for eachl 7; h1al+ubar 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 fuel for the reactio(5uw+n ,1auocluzg nxo 91nzxqc 5lw9o :9m,lns of Eqs. 31-8a, b, and c. Compnlz 5u9w9u9qcm1wo:n+ ux,z ,ao5ng1xc ol( lare to the 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 -a v3py*aiw yyv(*o-a 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 averagm0z nn,2nw;ite, what minimum amount of deuterium fuel would have to be used in a yei0zt n 2;wnm,nar to supply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carri;u tf. e3t3pbqq4as*3m lk3ewff0dt;ju da*+ed 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 ran on "d-d" reactions, Eqs. 31-8a and b. c+b* m v6f-)f;o9crqwi6bjip Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reactor iqvo9)c6ibw p;frm6b+-c *fj , assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if itnl 8wf5f t/pogd)u9r4s 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 g 5nfguw84/)pldor9 tfasoline, about $5 \times 10^7\ \text{J}$.
   $ \times 10^{9}\ \text{J}$
   times more than gasoline

The energy output of massive stars is believ b(d2ck y.awmok-0ov.t ad y74ed 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 cycle. (b) What is the total energy release? (c) Determine the energy output for each reaction and decay. (d) Wh0.(dwao4obc k t2 vky. -my7day 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 the -)da :ztmn pnfu.+ 5el6*e sg;us-c qocarbon cycle to that for a nl+ zqef6*moua- :.; 5gpsen- dscut)deuterium-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 wn-lk 2w3dv 3x$\gamma$ 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 as7*cy t,5y(gy41p aliy sjak1 j much biological damage as 75 rads of fast neup5* ijk1yt(s1 g 4 yyalaycj7,trons?    rad slow neutrons

  How much energy is deposited in the body o z 1eiujjj sv;bl+ t1rejp2p) uv7:d55f a 65-kg adult exposed to a 2.0-Gy doud1:v+i7;sjezu t 2plp rbe)j15j5 jvse?    $J$

  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 und5k/vm t5tr-r zfw+7i3odtec,glp b.e 5y83kwergoing radiation therapy in which protons with an energy of 1.2 MeV are incident on a 0.25-kg tumor. y z .fk5,/rp5w5v- 3detg+37wo c8titrebmkl
(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 mm+yym:b s tm..nqs;+uo -x v1$_{15}^{32}\text{P}$ (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 t, v4t5/h 6u7elkbc askh9nu 83av yiqz a0(gk3hat this is consistent with the two definitions of the roentgen given 6k0ain,/bkvl g9u vea5z83k47 uq3y schht(a 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 viuk 5dv09an;dd7)lcxa)3;w in jc f/ $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioact lm1q,3in/4qy.jgqbo ive $_{53}^{131}\text{I}$ 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 o 36ypl5yy ezjs19yer. bnscu o4 /,c:if 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 photons needed t ,ddnvicbstk 9k8 *1c*o produce NMR transitions in free protons in a 1.000-T field. In what regd ,nc*d9b1t*ckksv8 i ion of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombardilf2pukiz5 ,*jb 7*s rvng $_{4}^{9}\text{Be}$ 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 conv - 6ek)ojzio4mwiv3n2ersion factor from kelvins to k4z-2 jv i wonie3ok6)meV 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 urar z4sk3: cv7iwbkh3,0b3x bclnium 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 averaal (ufx k2a,mh:uo :s*ge yearly background radiation consists of 21 mrad of X-raum2 asak :ox*:l fhu,(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 kt*p , rt6n/uehydrogen on average. Make a rough estimate of the total deuterium in the Earth's ou 6t/rk nt,*peceans 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 nuclear powerpa0sdu0e*z7w m1lm1k 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,, for the proton-proton cycle in the S1onr9kgr0 ,t aun, 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 to calculate the "heat of combustion" per kilogram of hydrogen fuel and compare it to the heat 1o,ar k0rg9tnof 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 ayp2snm fzjqfcq kd p20/ c52f3r:x3oal4ag1 + rate 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 evoh:q.v.ixrw)x lution, 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 conta2zn q7a 1zxc hj0soc;6rwq.o .ins 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 accidzbo1gh+c gb(5 w;ue0m ent occurred 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 helig,;(qd8b c klx-)xtpcum abundance 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 th:ybg:7dui tg; e same activity, 25 mCi. Source A emits 1.0-MeVyg;u ig:b:dt7 $\gamma$ 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 py(9 sb0(:vw q*et- l3atzhzs 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 $    $\ \text{mCi}$