Fill in the missing particles or nuclei: ,j/wjp: d,pki h3jl*+zvky e5
(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 producin8y3 :yoss;44yc mo xkig 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 0lvzajaq o2l40 v0ik+$\beta^+$ 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 the4f6c ;3jvss d k:uh :rntk;w7g form of thermal energy - but the thermal energnw6jsvs73 k fud4c;;htgr :: ky of what?

The energy from nuclear fission appears in the form of thermal enetxp5 * q*8hp 0mhw8 ;jcqek5j3krq n7yrgy - but the the;7jq hwh pejp53k 0q*qymcrn 8k58tx *rmal energy of what?

Why can't uranium be enric:r meipyw-plv90,rj1)8 hnkhpz n2p a2t 7 g)qhed by chemical means?

How can a neutron, with practically no kinetic ener ciuu cra85.gj w4646nyf4 3 gagrxf8sgy, excite a nucleus to the extent showf4i6sanc4uxyuagf83.r rwjg6g48 c5 n in (Fig. Below)?

Why would a porous block of uranium be more likely to ex ti(x,nksd0d y(. h n4e swd2u2u:; k8y7txzeuplode if kept under water r(n.d4,e 0;xus hw k:x t8de2 z(n7kydis2t yuuather than in air?

A reactor that uses highly enriched uranium can use ordinary wato kry6g kl93(9jme y*fer (instead of heavy water) as a moderator and stiyklj( oy939f*6ekmg rll have a self-sustaining chain reaction. Explain.

Why must the fission process release neutrons if it is to be usefucywdde/ 3i i56l?

Discuss the relative meriv q;+x -7gdaw7m(aopkts and disadvantages, including pollution and safety, of power generation by fossil fuels, nuclear fission, and nuclear fusod a7 gkvxp-7(;+wqma ion.

What is the reason for the "s sau 1xn9:kmu*iii/a2 econdary system" 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 the/ax um i*ni9sa2ui1k: turbines?

Why are neutrons released in4 z4xvxr dm5b i z941piygmdz*kuv5ldb 28(e 0 a fission reaction?

Why do gamma particles penetratd.xh9oj vee5 ,e matter more easily than beta particles do?

A higher temperature i8nyzh 2wp z*o9s required for deuterium-deuterium ignition than for deuterium-tryw nz9 8*z2hopitium. Explain.

Light energy emitted by the Sun and stars comes from the fusion prosyn0sy4mex) rg0p +9rcztz) -cess. What conditions in the interior of stars make this possible)0)ptrzy -gxszesr9m 40 +yc n?

How do stars, and our Sun, maintain z.v ,zei(dlw1 confinement of the plasma for fusion?

What is the basic difference between fission and bvox4c.9 9esi/yc la8fusion?

People who work around metals that emit alpha particles are trained that thex74eco:/c dm-lxf+ e vd),n0yif 0w4alzmk2wre 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 agaiw-l ,mw x7d:4)d0z2fx yakn/c+ofe0lve4mcinst machining the metal. Why?

Why is the recommended maximum radiation dose higher for wgn xj0y(v1q-h4nrohv 3+zf7s omen beyond the child-bearing age than - vfjh zn+1(0ox4n7hqrvyg 3sfor younger women?

Radiation is sometim-xh* xo esp caknnh 1v3axgcq*x 11q ;s10io6+es used to sterilize medical supplies and even food. Explain how itq6hn phn1 1ioaq0ex-sgv 1ox+3ks **1xcxa c; works.

What is the difference between absorbed dose and effective dose? Wha2s 17accgi8vocr xdu0h wf8. 0t are the SI unid2cfiw u0 r1a0hcgcs8ov78 .xts for each?

How might radioactive tracers be used to finttx g8s3-z a0kqrkh-+d a leak in a pipe?

Natural aluminum is all ybayd.:,3lv (o :onbf$_{13}^{27}\text{Al}$. 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 reac z+k.0ij;f1a64-wj- cunr wkq d4x -h vyd,xxbtion $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 ela.5d gxhm p+3x7 zz0mnergy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction;c2zz l/q98dk 64lb. sshsx8 hce yyjdov91;w $_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 c a,.ttm:dbk 5$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 fp(6 *k1k 5ixg jg5u 2hgah+cfdor the "capture" 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 producto.enxy5w im83bcy u: :s 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 reactioz, )h s.rl rb60 p:nk6lb2glbcn 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"gg86y.oocq p( 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 following nuclear vny,go (y/wo9 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 i /qalv u2 u.yylw9o*+v euu34bn 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./m,n7tm,mk: 3 .t hwqy- qyjux 31-4? (The masses of /xmh3u t mtwk7: mq .qj,-yny,$_{56}^{140}\text{Ba}$ 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 +odhnhz 4eo r ps4+u3awxb0 5/:c pwg5reactor? Assume 200 MeV is released per fissipc50do5z 4wbw h+4 axo/3rhn g+ :uespon. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is about jpb.psv sbt 8ol1a: -9ru:1gu200 MeV per fission. What fraction of the restr19tu8 .loup 1sjs:gvb-:a bp mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reacti0p x-vvj(:grnon $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 consumptionu27sn 5 x d*rn/pfsg1j, day and night, in a typical house is 950 W. What x7n2g5ju psd 1 /fs*rninitial 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 of 5 p*;x2k cdsr47rjh a6adpbl($_{92}^{235}\text{U}$ 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 /9 p r+.ja;bdwy gmn1l$_{92}^{235}\text{U}$ 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 g* nwvrnu:l.b:u 9)/xa2ts xnkinetic energy of protons at the center of a star where the temperature is9.:lr:)nax/ nnx *wsg t ubv2u $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released in t5v,r9(0vdohh .te-pe dj9 ckthe fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released when two deuterium nuclei fuse to-10rk2kybkcozxrq u2,lp4 r*kkdr1v) ;pc 8x form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for each of the reactions ofEqs. 31-6. x in8k u5 j71hv6 tww9.uzae(t
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 reactions of Eqs. 31-8u0wf -c/,d efva, b, and c. Compare to the energy release per gram of uranium in fission.-0c/f,fwvu de
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 b) a+mp4es0ian $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requires 950 W of ee oov+7k1 anm;ot7 yg4hsu.0clectric power on average, what minimum amount of deuterium fuel wo+7 m1ek.v aoocso 7t; yghu04nuld have to be used in a year to supply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carria5p wb -wm-mvgfb-x6 +( 3ogzied 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" reactikbr(4h2e;d7 ag9j .hz u0cc4fu 4a twxt,,j ydons, Eqs. 31-8a and b. Estimate how much water, for fuel, would be needed per hour to run a 1000-Mukda4 e.x bc7cry9t4zh2dj0 (wa4g ;jhuf t ,,W reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is conw;mucam9z*) + sx *m(lf xo;httained 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 burning ahxl*m; ozx*; fwcm)t9+s u (mof 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 blk2tv 3 a1yk:kelieved 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 k:ykt 2lv1k 3athe 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 tjginwe c( j85(hxls5 /he first reaction of the carbon cycle to thatjexgln8 wj(c (55s/hi for a 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 g2 hc c s)c6;1valri7w11q coh$\gamma$ 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 a*m)3g0pg s gv75 rads of fast 0sg* vga3gpm )neutrons?    rad slow neutrons

  How much energy is depositedq u roni8xt352a/md:n in the body of a 65-kg adult exposed to a 2.0-Gy doxdu2nr:3ao/8n5 miq tse?    $J$

  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 with an energ h5ibf2b1 v ekl j jwwe7,-75eu:l )nd4iocf3ly of 1.2 MeV are k4)w5-w v l7je ,c2udb75ebnoj i ifl3:hlfe1incident 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 :bh 48.gyby(zntt zo:$_{15}^{32}\text{P}$ (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 tx9egb71zbc6 i tv(-b khat this is consistent with the two definitions of the bgeizb7 kvx 1t6b-c9( 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 a6/ 3y/ ps2hvk;r(gnl 6lr bbsr $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactivegyf59f .sct-+j fy t5d $_{53}^{131}\text{I}$ 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 typicall93gel 3 tzn8swbyu 9+xy has an activity 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 photons needed to produce NMR transitions in free 3.crm+e 7:, hw1yfeuxvj3 tuxprotons in a 1.000-T field. In what region of the se,cxw+he3m tr:vujufx71.3 ypectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombarkkf w)97yl w g6 jbgcp72+zn0eding $_{4}^{9}\text{Be}$ 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 convekacc3kh gva7* -d(j b8rsion factor from kelvins to keV using, as is common in this fi8dv*hja kkba cc7- (3geld, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching bllx o)25j(* alof(a zuranium 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 backgr9p. h;y)jqob(oau 9lvound radiation consists of 21 mrad of X-rays a o9a.qj) pu(lvy9boh;nd $\gamma$ 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% 14dqs ni92gu+h x4tf1 ztoko-of natural hydrogen on average. Make a rough estimate of the total deuterium in the Earth's oceans and estimate the total es1t4dnqxo 24 i-9tu k1zgo+hfnergy 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 power plants that produce 34 jpm4e oq(;e9l t:luu+0py3eb,1okoirq: 6km00 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,, bk:ekr/(g6 kfyul -w5for the proton-proton cycle in the 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 to calculate the "heat of combustion" per kilogram of hydrogen fuel and compare it-kl(k6 rbfky: e/gu5w 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 of abouc) m r*q9awg5vt $1400\ \text{W/m}^2$. 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 hx nq:43ezvaen n/97h+tump2 evolution, 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 ab:anom /d)cv ;kout $0.10\ \mu\text{Ci}$ 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 reactorpot /do:v7ky z7av1:bep vh;* accident 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 helium abundance can burn helium in the react38w8 7khjnc zmb3rz:oion $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. 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 souqv aj 3/zg+)mx50psrsrubg,: rces have the same activity, 25 mCi. Source A emits 1.0-MeVpr s)5v+/0a zrxg gm:qjb,s3u $\gamma$ 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 me: 6xstmg:azo) dical 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 $    $\ \text{mCi}$