Fill in the missing particles or nucle:;m9 e2x wa2wcofty7 c 2dx2vdi:
(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 projecto6mvd9xdc l3b)1;bq 03olag biles 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 ; jk;uyov,* b-j tszt.$\beta^+$ 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 fj )f; an-pa+zx8yt w+cission appears in the form of thermal energy - but the thert ya; xnj-f++zawpc8)mal energy of what?

The energy from nuclear fi00nwprd7y 4zf ssion appears in the form of thermal energy - but the therma r0w7 zfp4nyd0l energy of what?

Why can't uranium be enriched by chemical meal4g6 , ykaslt-ns?

How can a neutron, with pryh(qaz, /4mcxactically no kinetic energy, excite a nucleus to the exteqcx(4 mzyah, /nt shown in (Fig. Below)?

Why would a porous block of uranium be more likely xig9-e*mz-joaj :ndw oi6ba0h27 j0l n3wu;q to explode if kept under water rathe7imo0qji*-:a od wb;nwhxez-nug6 2j 3a 90jl r than in air?

A reactor that uses highly enrichko fh9mv t:rqw+6 :.oved uranium can use ordinary water (instead of heavy water) as a moderator and still hq+rw6f 9.m:o vt v:kohave a self-sustaining chain reaction. Explain.

Why must the fission process release neutrons if it is tos9 j 3jpjbxfy9 :.of0/u: zxfi be useful?

Discuss the relative me2/nkqxk 9 :aunrits and disadvantages, including pollution and safety, of power generation by fossil fuels, nuclear fissionq:nkk/xua9n2 , and nuclear fusion.

What is the reason for the "secondary system" in a nuclear reacto0 3 groqql4qsk:y 71vur, (Fig. Below)? That is, why is the water heated by the fuel in a nuclear reactor not used directly to drive t4k10q uqv ly 3o7gsr:qhe turbines?

Why are neutrons released in a fission reactiowyg. h(6bfm9 xdeg5o90e rqf6o3zbv)n?

Why do gamma particles penetrate matter more easily than beta partifr9lfz.y f ;g:cles do?

A higher temperature is required for deuterium-deuterium ignit::9d- zve / nzsk/igy;ib cd b-gf..onion than for deuterium-trfi ki/g.-zce bbsn-d9o:/ yz vdg; .n:itium. Explain.

Light energy emitted by the Sun and stars comes from 3gdo g.z2) a2,v)pqine 9pn vvthe fusion process. What conditions in the d2p3g nz9pvo)gva)q2.en, v iinterior of stars make this possible?

How do stars, and ouul vmg;1 x it1xvnt9*.r Sun, maintain confinement of the plasma for fusion?

What is the basic difference between fissiv d5gza; qv d6)dna.0.5yiihron and fusion?

People who work around metals that emit alpha particles are trained that there -rzmv 2+c,sfo is little danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, c2 zosvm-+rf,there are strong rules against eating and drinking while working, and against machining the metal. Why?

Why is the recommended maximum radiation dose higher f*oot anj8y, /cor women beyond the child-bt, oya*co8 jn/earing age than for younger women?

Radiation is sometimes used to sterilize medical supplies anyrze4 0 +87e,g p hn5h;lngbffd even food. Explain how it wyl0 p gh+hfb n4 gz8,7nfe5r;eorks.

What is the difference between absorbed dose and effective dose? What a4 c/o1 7jgilrq* e-sz dq-qi+lre the SI units fo4rqio- l+ge1 z jdqcl-*siq/7r each?

How might radioactive tracers be used to find a leak in a pippjrrl )t* blkd3ta7c (d(b /o*e?

Natural aluminum is alwfx-s bpn0n a)pz:10qkv)1xp k*mvf(l $_{13}^{27}\text{Al}$. 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 rcj8ou1 3l 0vnd :d.agieaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 ra+ y m(s olwh/wns;b)/n5f t,xeleased (or energy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reactionp05 ;ay7wkykrpz3 cg.o2w(fce ;,dz d $_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 ap/yi a om;a5z3p-k( c6nhw2i$_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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-valuez urvt,qt(.y* 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 the mdh-0hzz b 0cf5icl09products 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"5fhv ib51h -xx 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" lf 7j(;ax,fydqhqx,k4e e f36nuclear 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 reactiontb7wp1 thw b14: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 reacx5xcvp6 ajjx ;ndt;58l2w kz :.akv:ntion $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy released inqw,u- wgf*tsto0la9lz5n 54 u the fission reaction of Eq. 31-4? (The masses of ol55 -u9n* azlq, g0ftw tu4sw$_{56}^{140}\text{Ba}$ 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 reactor? Assume 200 Me n-h kfu g0e(1n /++fxr1uorfuV is rele( n1fr0 gfk1+ /+h-rexufunuoased per fission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced amohh*u 5+jtcvi5 4gbk09d ( gby a fission reactor is about 200 MeV per fission. What fractio+*5u0kd m( 5 tg o9ahbv4ichgjn of the rest mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission rew4 unf+. bn0hk()iw,yubxc d (action $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(a) How many neutrons are produced in this reaction?   
(b) Calculate the energy release. The atomic masses for Sb and Nb isotopes are 132.915250 u and 97.910328 u, respectively. Q =    MeV

  How much mass of $_{92}^{235}\text{U}$ is required to produce the same amount of energy as burning 1.0 kg of coal (about $3 \times 10^7\ \text{J}$)?    $ \times 10^{-7}\ \text{kg}$

  Suppose that the electrio,x.zkdi qvb7.p t(.u 6/ e+wdx,m smpc average power consumption, day and night, in a typical house is 950 W. What in7d ,,. m pv i/m. (q6k+xuwpstzxbode.itial 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 of3l mj-.rdw 7th2p j(ll $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission ofc5w sy d18l 6wgw(;fsp $_{92}^{235}\text{U}$ into two roughly equal fragments, estimate the electric potential energy just as the fragments separate from each other. Assume that the fragments are spherical (see Eq. 30-1) and compare your calculation to the nuclear fission energy released, about 200 MeV.
PE =    MeV
This is about    % larger than the nuclear fission energy released.

  What is the average kinetic energy of protons at the cu- 5fox.bslev)jf ct3i73 )dqenter of a star where the tempb f-qs jt.i )7v)xlfoud3 e5c3erature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy relqu cj(ti6rw1ab e7p*+ y2xeb) eased in the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy release, 1s*m. qur)hltos k)wd 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 each of the reactions ofEqs. 31-o/ )l(wyvd9-kb rsqz-st7sn,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 thlxa++yic; o2u e reactions of Eqs. 31-8a, b, and c. Compare to the energy release p+ x+u;co2iayler 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 relq;fa ehmy -xid/.d1v)h/y )v)j j8i vreased 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 ele46 6qpcr(bwp9m xltoop x,9n*s8asv6ctric power on average, what minimum amount of deuterium fuel would have to be used in a year to supp 8bp66,paw(nm t 6opqs x4cxrsl ov*99ly these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carried o;m:17.zap0od fbz yj6:fjmh bff 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 ox9o p dhgy1pn-,h6 pk.*:aa tbn "d-d" reactions, Eqs. 31-8a and b. Estimate how much water, for f-ph 9 xyt.dnkp:6o1hbg,* apauel, would be needed per hour to run a 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of w3h y oibs+,nu)ater if its natural deuterium is used in the fusion reaction of Eq. 31-8a? Co +bs,o)3yui nhmpare to 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 ofbd w)t0s*+ e 8hvdjqx7 xnp8;d massive stars is 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 cycle. (b) What is the total energy release? (c) Determine the energy output for each reaction and decay. (d) Why does the carbon cycle require a hwddp7 88dvts+eqx *bn); hjx0igher 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 carm :rde:::-.n ukidn jqbon cycle to that for a deuterium-tritium reactirdjm:e : :-du: q.innkon.
(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 ,+ *ey6kiyd d0 ijgco;$\gamma$ 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*-j:t,)qmnxp nbwq2 1e1iq ei much biological damage as 75 rads of fast neutrons? :neqieb 1xiq )2 jp*1-tm wn,q   rad slow neutrons

  How much energy is deposited in the body of a 65-kg adult exposed to a 2.0-Gy d-n)4 ls:5i4)h htno rr2.wtq 5fperqcose?c.45)p 5-wh:rfosn qhtn e)4l2 qr rit    $J$

  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 rs):en k: )h6dymz6 okyadiation therapy in which protons with an energy of )ys y 6:nkd eoz6h)m:k1.2 MeV are incident 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 9420kcz4b gzihhqi0s $_{15}^{32}\text{P}$ (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 onegb 4jpu/ q*b4j6m, v*ygca t;p ion pair in air. Show that this is consistent with the two definitions of the roentgen give va /jggcq jut4*mpp* b6y4;,bn 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 ac4+vs+9yij pw9maes 4b ja0roq8d3 6 i $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactv6rr4t9 * wrjqive $_{53}^{131}\text{I}$ 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 nbhcj;i /6ud kcf xb;2dqa5 o*q(3yi9 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 p 7) m qr,simqvukj3(j2rotonq rmu3)jm( i,vs2k7jqs in a 1.000-T field. In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the a8qcr6x;(a *vl ik, bnn+:myt neutron by bombarding $_{4}^{9}\text{Be}$ with the popular projectile of the day, alpha particles.
(a) If one of the reaction products was the then unknown neutron, what was the other product?
(b) What is the Q-value of this reaction?Q =    MeV

  Fusion temperatures are often given in keV. Determine the conversion fac9aj kt, nh6y53msa pa f3spn)7tor from kelvins to keV using, as is common ajn33)mhf ,t5sy s76pna9kp ain this field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uraniuyxxq i9 ,:;immm 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 *g+rjrp:qv r9sf myv-x)oy -, average yearly background radiation consists of 21 mrad of X-rays and-x-qvf vrogjmy)sr ,+ p9* :ry $\gamma$ 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 average. Make a rough estimatel qut/8e)c yl) of the total deuterium in the Earth's oceans and estimate the total energy released if all of it were usedy)qul l e)c8t/ 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 nuclea:cqqc( 7-r7 izemmugjt 4+v r0r power 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 theff, cxhlb g.zlno7n0r +,)pp ( 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,br z)gnpp ,0(lx+.fho 7c fnl it to the heat of combustion of coal, about $3 \times 10^7\ \text{J/kg}$.    $ \times 10^{-14}\ \text{J/g}$
This is about    $ \times 10^7$times the heat of combustion of coal.

  Energy reaches Earth from the Sun at a rate of abou (rf :gw6nw+rbf bgr44t $1400\ \text{W/m}^2$. 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 evocxaw0lvr m) irv+jyv/e, /.f sa56ss3lution, 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 cj+n4frjx.q0boit)uo8rz l7j+c(0 cr li)+k l ontains 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 occurred at C-+h i fzq2clb d usvc8fr)pzx2u: 61/ehernobyl 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 the0ahyq-paa e94z*o,px 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 activbqrxb kl pgqm112*y(n3ru :(zity, 25 mCi. Source A emits 1.0-MeV 3q1rb(: nxg2 *bky u(zqrml 1p$\gamma$ 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 gi8 d3ue2 w 9.y6jcq2c fuis(9utij5sgbven a medical 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 $    $\ \text{mCi}$