Fill in the missing particles or nzz09 0fjs/w hcp8 )emmuclei:
(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 projec / e0ovy9uvy8ztiles 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 ( ,iz:bn5(ptt8r-sz+hf n ocp$\beta^+$ 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 th7 zvl0 /fobdp)e form of thermal energy - but the thermal ener7bf0pz/ lo vd)gy of what?

The energy from nucle+4v8 0p1rpznt p9gnnp ar fission appears in the form of thermal energy - but the thermal er4p0n8n pppt 9v g1+znnergy of what?

Why can't uranium be enriched by cfg8z)qv qvm t1r 2c+a2hemical means?

How can a neutron, with practically no kinetic energy, excite a nuls*b/ovklbaif ;y6j ; 9 vpx2l, h;:fdcleus to the extent shown in (Fig.lbp;xhajf il2/sl; oy v9* f:v;6 dk,b Below)?

Why would a porous block of uranium be more likely to explode if kept under wci,f-um6sj tx:q g8/+8 r; y blszqx,wate8/8 ix,uqr6szjymgl,+ cfb;sq t:wx -r rather than in air?

A reactor that uses highly enriched uranium can use ordinary water:lt w*e4+kj36z:bhe -pkkkek (instead of heavy water) as a moderator and still have a self-sustaining chain reaction. Explat6kkb+peek:kezw j4 *3l k :-hin.

Why must the fission process relea6o1jzio yc6 7i r.o1jose neutrons if it is to be useful?

Discuss the relative meriti jhrs0q,5spqak s 8,4o,(hd ns and disadvantages, including pollution and safety, of power gener 50(8ho,jhisn,4qdsarq,k psation by fossil fuels, nuclear fission, and nuclear fusion.

What is the reason for the "secondary system" in a nuclear reactor, czn7wf9 75oxex;o*rw (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor not used dix 7ew7no ro*zwcf x9;5rectly to drive the turbines?

Why are neutrons released in a fission reactioyeivb*74(/hrj kbz3pto z1q wu(i 7k1 n?

Why do gamma particles penetrate m3 er mvzk36yyki7apy8 94(pxmatter more easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignitio z a32jdcskj.*n than for deuterium-trit.jj d czas*23kium. Explain.

Light energy emitted by the Sun and staudn5cp) m yq,+6 ej0l80ge 7aqzanup4rs comes from the fusion process. What conditions in the interior of stars make this possibl5ud48znpp)mc6 naeju+0q7ay 0,g q ele?

How do stars, and our Sun, maintain confinement of theyw44b/8ebhibit/(hj ag3t x; plasma for fusion?

What is the basic differe;66i ln:e 0 thnxwj*ybnce between fission and fusion?

People who work around metals that emit) 0lb)ij;zv;y k ;4su h5mydgn alpha particles are 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 whiu)hs;z; v ;0ymk)gji5ny l4 bdle working, and against machining the metal. Why?

Why is the recommended maximum radiation dose higher r qv-h dkduhryontp;. 1.x,.1k5l0ndfor women beyond the child-bearing age than for younger wo1.hrkvl .x nk y,o1u-;tdpr.qd5hn0 dmen?

Radiation is sometimes used to sterilize medical suppli( 4lux4 +pljk481oteq ggpjw7es and even food. Explain how p+up8t lj4xl44(o7wekg1jgq it works.

What is the difference between absorbed dose and effective doseivdrb*d k;+ad79v k ;;ohzvq ;? What are the SI units fqo*vad ; bid; r7v;h9v;kdz+kor each?

How might radioactive tracers bz8 d6a k7pm562 dwuiy ffay)4be used to find a leak in a pipe?

Natural aluminum is allck;xfs,:zcexd j1 d :3 $_{13}^{27}\text{Al}$. 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 reaw4( ;hics /* rx 1wf0b,sdbznzction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 rehl6ifbt (;k wwd+ j;r7quired) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reactionrb.r 3 1mw owh 2*9.fo-psxuvs $_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reaction3gvu nw,+guo)x j/)fm $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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-valu9wn :hqbztg0-bn/ws m,*s ok)e for 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 7zda if +2an+yoko3 r-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 "strippi 6(voeglzpw 19b1y4i wng" nuclear 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 lz plg( l)bditki1+0) $_{1}^{2}\text{H} + _{6}^{12}\text{C} \to \text{X} + \alpha$.
(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 reaction: z7mf2 au)p0du 2e*xbwj u;ll5$\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 releasefx,n -9emw(nk79qo i 9v; hdltd in the fission reaction $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy released in the fission reaction of Eq. 31-4?/bwuih*y/ uxg: ulk65 (The masses of b 5u/ /hiy lk:xw*guu6$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take pl tyau)5)5ll/pc;v eyeace per second in a 200-MW reactor? Assume 200 MeV is re e5;vy5)y )altlc ue/pleased per fission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a zm+6 zdayzp1* ekzs to,ggi, (o2px8hcx* .e0fission reactor is about 200 MeV per fission. What fraction of the rg*yzgcez 60 ,*i .eot2 8ap1zh+so pk( ,dmxxzest mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission rea/oeu2 cuc5k n5ction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 nbck8 (v2 ee.sand night, in a typical house is 9vs(e kbe nc8.250 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 ofbf/*/2 t bhjjn 9fs8ij $_{92}^{235}\text{U}$ 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( lxjf /bj/+qw $_{92}^{235}\text{U}$ 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 energ ma;i1)6ko ):qeo oud 6gz8kdly of protons at the center of a star where the tdkz )ol86u)odq 1aoekgm:;6iemperature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released i5s )b s;dje)4urpipzewk d*1oe7y 6 (etz81n qn the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released whh 6venpc pe:o; dr s)s /tcd56.gow-j2en two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for each of the reabf; w.x(pegnavxp*b01d9y 1yctions 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 reactions of Eqs. 0au v,ru6pw:jgw9 ;ama/l3rnt vb *m+31-8a, b, and c. Compare to the energy release pew p +r6u9 ;nt,:g mma*uaj /vw0l3bravr 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 releasefb4 xjkb+t-(vd 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 powef;m e1bz eamz ;c ,s/s+1.noqur on average, what minimum amount of deu1q,umfsenm z zso/ec; b1+;a.terium fuel would 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 uak8 57y jicy.eyk0f.x ()bunud6h0m 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.l;jr jl, a:jy:) qut.t Estimate how much water, for fuel, would be needed per hour to run a 1000-MW reactor, assuming 30% effq tu;,)jya.: tj: lrljiciency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if its natural d-lis* aqr* mr p /bad.d3khb6.euterium is used in the fusion reaction of Eq. 31-8a? Compare to q-ba ma*dilrdhrp3 sbk6/..*the energy obtained 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 believed to be due to the ca)ew. gqt (tiljz (p54urbon 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 )weluq.5jigz ptt(( 4energy 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 e , :b2k)n1ustvv7;q i my9atureaction of the carbon cycle to that q 1tvyk9m:; vet, uu2ia7)bn sfor 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 m8)rj;3gkh*ke l ww4e $\gamma$ 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 y.g, mpf ;x;yxv( wx9kmuch biological damage as 75 rads of fast ne g fxmyw; .yxkv9(;,xputrons?    rad slow neutrons

  How much energy is deposited in the b:4rb6i mcar0v 1mhoa . p3ryt+ody of a 65-kg adult exposed to a 2.0-Gy dose?o+r6tyv 1im40mcb . ap: ha3rr    $J$

  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 rataas z+0dxh; -y3qk/t(a,tt;3jd pf ediation therapy in which protons with an energy of 1.2 MeV are inci z ;,+0jatp/ aey(-sqtkhdaf3d3 x;ttdent 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 to ap2+yt,mha:3wu9 q $_{15}^{32}\text{P}$ (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 is consiszl-m pfn.ov4 3i0 5vocr3x* gstent with vo53fov0lrmg3*xs - i4 c.znp the two definitions of the roentgen given in the text.

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

  What is the mass of a c8ctsls* )u2 qa uh,:n$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactivnrh0nz)(usyc74i )e we $_{53}^{131}\text{I}$ 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 typicallywm wagc1( 1b 2zj:)krx 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 transit jmkq,zx,uk-,ions in free protons in a 1.000-T field. In what kx,,,quz m -jkregion of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombard wpr2mu1,-/.u *bl xlebt(iyying $_{4}^{9}\text{Be}$ 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. Determi4d s06kssl9) zj(5uij04y dn4lkxh c q-(cpvine the conversion factor from kelvins to keV using, as x0 ilsv nc 4j(6dss59h40uz4 p y-)ck(lijd qkis common in this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uranium is by diff -*i5qebzb 3/teb* mmzusion 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 background radi/ 9v;f:ikwbwdation consists of 21 mrad of X-rww;fvd/:9bk iays 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 dt-lz j4g npe0v ia 8nj;1n2a8on average. Make a rough estimate of 8i0p td4a ;enajjznl2g n-1v8the total deuterium in the Earth's oceans and estimate the total energy released if all of it were used in fusion reactors.

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

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

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

  Consider a system of nuclear power plants that p6m2be8gma;8nq*z v:a b g-(6u ihhvejroduce 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 thef zrr16-b1n0r zwl/+i c7cdhe 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 1bzci h/6rcdnlz0r7-1+w f rekilogram 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 th()idvtjh hc t; f9y(8be Sun at a 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 of4; a;2oblij ph 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 containi)s j7atl5c1 e;mq6yb s 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 occurrnyms9n:y6m0hv: cf7j e:pw w :ed 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 ine,,r9u 3 9ag , kqu*djeii:egy 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 ,dskc+f)ak 6wzss5 ,gactivity, 25 mCi. Source A emits 1.0-MeVw+ ga,5zcs) ,fds6ksk $\gamma$ 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 testby(l/; mf8s/(w+bagl cr2 ud g 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 $    $\ \text{mCi}$