Fill in the missing pa3di4lmoka czx57- 8bbb/id v5rticles or nuclei:
(a) $\text{n} + _{56}^{137}\text{Ba} \to ? + \gamma$
(b) $\text{n} + _{55}^{137}\text{Cs} \to _{56}^{137}\text{Ba} + 2?$
(c) $_{92}^{235}\text{U} + \text{n} \to _{38}^{90}\text{Sr} + ? + 3\text{n}$
(d) $? + \text{d} \to _{79}^{197}\text{Au} + \alpha$
where d stands for deuterium ($_{1}^{2}\text{H}$).

The isotope $_{15}^{32}\text{P}$ is produced by the reaction: $? + \text{n} \to _{15}^{32}\text{P} + \text{p}$. What must be the target nucleus?

When $_{11}^{22}\text{Na}$ is bombarded by deuterons ($_{1}^{2}\text{H}$), an $\alpha$ particle is emitted. What is the resulting nuclide?

Why are neutrons such good projectiles for producing5zu 7 a33rl s,xndkfm+ 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 +urm6 o2 vib gi1av tr2a*/)jpzm kk6($\beta^+$ 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 fi3j9 ho2i6md yqssion appears in the form of thermal energy - but the thermal energ y3q9ho6dm2i jy of what?

The energy from nuclear fission appears i7oyrkc a o*p14t1 dj,on the form of thermal energy - but the thermal energy of what?r tojo*k p7,ocya 4d11

Why can't uranium be enriched501upu-) e jjtbxij/x by chemical means?

How can a neutron, with f,pjx.)v2 avuo ;qjmuw +a62ppractically no kinetic energy, excite a nucleus to the extent shown in (Fiw6.xa a) 2jp;m ,uvp2foq+u vjg. Below)?

Why would a porous block of bk+ v (j ,g.q-)zk:kt)jkuuaxuranium be more likely to explode if kept under water rather th+jv ,:x bz-uku(jt .k)gqk)akan in air?

A reactor that uses highly enriched uranium can use ordinary water (invoh*m.c8vpi qn:x7j 0xjbrge7./ ; cjstead of heavy water) as a moderator and stij *r chm q8bj.7:vei jp/;07cgnvoxx.ll have a self-sustaining chain reaction. Explain.

Why must the fission process release neutrons if it vs7eatx3 +6 kkis to be useful?

Discuss the relative merits and disadvantages, including pollution and safetyzsi -z3 88gly5ntf9 qdlo7+ew, of power generation by fossil fuels, nuclear sgfl8y53 8qi n-zwd9+le 7otzfission, and nuclear fusion.

What is the reason for the "secondary system" in a nuclear reactu8ss66opzx0 k or, (Fig. Below)? That is, why is the water heatoxk s6s680zup ed by the fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in a fission reaa +hn1 m+g/ogpm5 ckaea07j w)ction?

Why do gamma particles penetrate matter more easily than beta particl8qlzlx,+um 38;t : 6vwxsj: ccouc ;zves do?

A higher temperature is required for t+7dqhj m(w.0uaf 9qg deuterium-deuterium ignition than for deuteriuu a7( twmhqjqf d0+.9gm-tritium. Explain.

Light energy emitted by the Sun and stars comes from the fusion procet; 5cs;vzpc6q t8v4x ec;or2)zgf5f qss. What conditions in tz o c 68; ;vpftx4f5;qvcg5er )z2qtsche interior of stars make this possible?

How do stars, and our Sun, maintain confin .6dpc nk*o:n: fze5xgement of the plasma for fusion?

What is the basic difference betwe 2re3o jjnv3k2en fission and fusion?

People who work around metals that emit alpha particlg5;ndc-0fk3q gwo39u e1wvul es 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 w93fnuev lu-c o3; w0w1k5gdqghile working, and against machining the metal. Why?

Why is the recommended maximum radiation dose higher for wom8nddsa-r9eik:a bvc7-jya9, ut t/ t 5en beyond the child-bearing age than for younger :,aa 9tr9v id-uc-kn5jbd7es ta/8ytwomen?

Radiation is sometimes used to bb).y 3d*e:ahl)e tdbsterilize medical supplies and even food. Explain how itbebltb).)d y: *e3 hda works.

What is the difference between absorbed dcmrh ,e .rbm 9ell./g-ose and effective dose? What are the SI unit.r9 l/rbemh-.eg m, lcs for each?

How might radioactive tracers be used to find a leak in a pdajt9+p*l7b we2n- 0 djb*zqpipe?

Natural aluminum is al yx8)8n 6w/; iov hhsc4ocl*h2ap .qxbl $_{13}^{27}\text{Al}$. If it absorbs a neutron, what does it become? Does it decay by $\beta^-$ or $\beta^+$? What will be the product nucleus?

Determine whether th*8 xq/r0g7wc tl1usv xolsrf1t-3hu ) e reaction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ requires a threshold energy.

Is the reaction $\text{n} + _{92}^{238}\text{U} \to _{92}^{239}\text{U} + \gamma$ possible with slow neutrons? Explain.

  Does the reaction $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ require energy, or does it release energy? How much energy?    MeV

  Calculate the energy released (or energy input required) for the reactioxdd,-3xaz k e69 eqj4fn $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction 27/a j tv d 1m*0y:ib2yxestt:odl9f s$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reactionboct)4u8c ,qdh(y+iclm 5.ic,vmgm : $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 "capture" reaction q m(ms:cb-) zj$_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of the products of tnpqv*w :kz8)wb*j 4eche 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" nuclea wk6m);f1q)w92zfiq s os/fyhr 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" nuclea6)anxaky :dtb w( +ds5qhxj(3r 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 reactioxdhda; /rskh4:j e j9;xpfn9+n: $\text{p} + ? \to _{16}^{32}\text{S} + \gamma$.
(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 reactiorefpfm,qbo46h32 n x 9n $_{92}^{235}\text{U} + \text{n} \to _{56}^{141}\text{Ba} + _{36}^{92}\text{Kr} + 3\text{n}$. Use Appendix B, and assume the initial kinetic energy of the neutron is very small. Q =    MeV

  What is the energy release. t0p9iqhg14.u/spt ld3qfi1 prptn* d in the fission reaction of Eq. 31-4? (The masses of gppfqst q pr1.t*.0ilp h13ntdi /u49 $_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per s)pnn7r)q a )ri1 jpl+vecond in a 200-MW reactor? Assume 200 MeV is relea nanp+r)vli7r)) pj1qsed per fission. P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fuu61xau 4v2ft f) +zk zdbak-;ission reactor is about 200 MeV per fission. What fraction of the rest tx+4u azzau)2vkud-;kf1fb6mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reaction bnfk*1p l-+u+ o is;aa$_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(a) How many neutrons are produced in this reaction?   
(b) Calculate the energy release. The atomic masses for Sb and Nb isotopes are 132.915250 u and 97.910328 u, respectively. Q =    MeV

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

  Suppose that the electric average power consumption, day and night, in a lbv q9;uu3;/ dg xe:ixc7ex8ctypical house i7ex3;x d; qc/lbu:gievux c98s 950 W. What initial mass of $_{92}^{235}\text{U}$ would have to undergo fission to supply the electrical needs of such a house for a year? (Assume 200 MeV is released per fission, as well as 100% efficiency.)    $ \times 10^{-4}\ \text{kg}$

  What initial mass of/ 3 y13c j5xbglttxgb;w 0uz2f $_{92}^{235}\text{U}$ 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 ut3mb/af4 ht cmu(9j :$_{92}^{235}\text{U}$ 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 of7btqn * v,fnf9/gqk pk2bn1/ m protons at the center of a star where the temk2b pqf*n9qfnkn,bmv/ 7g/1t perature is $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy releaqejv3oz0a9 a tqe 65m9sed in the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy rex e 0r4r0+jgp8ob(sod leased when two deuterium nuclei fuse to form $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value st8u)4f8 x/jw v mukpby+ated for each 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 reactions of Eqs. 31-86voku -z/7fz. ;6p*zqcuzjmfa, b, and c. Compare to the energy release per gram of uranium in7f.-*u kumzzjcz; 6 6o/qfzpv 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 releasepxkv-anxz, 4 lbgr 4w-.6 0r( xcitfb6d 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 average, what minimu,* m dkpcs(q1um amount of deuterium fuel would have ts1mc(*kd ,pq uo be used in a year to supply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carriedawae+l43t-su ve.c 9x 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. Estimate j6 r.l6y2aa;* zmvpf- suspkxy 3w1z8how much water, for fuel, would be needed per hour to run a 1000-MW reactor,rp6yxw km62- a18*zp;syv3s.flu za j assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if 9mia+s9 zelu56; hbgoits natural deuterium is used in the fusion reaction of Eq. 31-8a? Compare to the energy z6;sua b9goe9 +5ilmh 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 sta:7i x: 5,p 3 yiw4mrry/pvfcafrs 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 enerv5m,y7fxf:r w:i4rya3p i/p cgy 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 81 pmk:v)dw,4hwpdp 5fzs1k mfirst reaction of the carbon cycle to that for a deuterium-tritih)d4fvp1w wmpd z: 5,18mksp kum 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 bxnd1sp d7ha +(hh6p3 $\gamma$ 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 mm; s.cm-j 89yacxr 9mlglpa5+uch biological damage as 75 rads of fast neurmm;mg-j cp 5+c xls.8l99aa ytrons?    rad slow neutrons

  How much energy is deposited in the body of a 65-kg adult exposed to /q2v)e*8qskgtk kk8 o a 2.0-Gy dokg8k8 k /)qe2vts okq*se?    $J$

  A $0.025-\mu\text{Ci}$ sample of $_{15}^{32}\text{P}$ is injected into an animal for tracer studies. If a Geiger counter intercepts 25% of the emitted $\beta^-$ particles, what will be the counting rate, assumed 85% efficient?$\approx$    $ \ \text{counts/s}$

  A cancer patient is undergoing radiation therapy in whicq hlh3sp3o9uo03;h/y9s lwrg *ub 9hb6e vga/ h protons with an energy of 1.2 MeV are incident on a 0.0ggs9p 3r;sl*o v 9blh wu/be/ h3oyhu 6qa39h25-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 e0 u15so;dobn/p7h ly c9pdw)$_{15}^{32}\text{P}$ (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 t3 i+k arah1mc9his is consistent with the krca +ia1 39mhtwo 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 +c.d: db8pxh sc 1kuh6$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radiondan0/rep7;2w8 ozffsvx 4 ,pactive $_{53}^{131}\text{I}$ 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 activieck;gf4tq-l: -zjd d3 ty 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 photoh,mnq3za ft:;543 litvo ;uafns needed to produce NMR transitions in free protons in a 1.000-T field. In what region of the spectrum does t3n z; lfa 54atiqf;u:vmo h,3it lie? c =    $m$

  J. Chadwick discovered the neutron bid-1 hrq lx)+wy 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 giv 6 o1 hevebf8pi-3wzc/en in keV. Determine the conversion factor from kelvins to keV using, as is common in thifw8 zoh16p/- cv3ebies field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uranium is by diffusiond9tsb 1s (d)ocscc dk:jp-6* a)xf1n8q ymj/h 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 radiation consists of 21 mra x.peo .9ytssvvr,lcw1*+ 1gl d ofp 1s+s .x*9llev ,v1r cywgo.t X-rays 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 on average. Make a 4jkex8 gtba: 5mmx(u6rough estimate of the total deuterium in the Earth's oceans t8uxa g6j:b4e5x(m kmand 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 p:6 gv ;kj+f)pny9 qgwus2 +uzbroduce 3400 MW.
(a) What total mass of $_{92}^{235}\text{U}$ fuel would be required to operate these plants for 1 yr, assuming that 200 MeV is released per fission? $\approx$    $ \ \text{kg}$
(b) Typically 6% of the $_{92}^{235}\text{U}$ nuclei that fission produce $_{38}^{90}\text{Sr}$, a $\beta^-$ emitter with a half-life of 29 yr. What is the total radioactivity of the $_{38}^{90}\text{Sr}$ in curies, produced in 1 yr? (Neglect the fact that some of it decays during the 1-yr period.) $\dfrac{\Delta N}{\Delta t}$    $ \times 10^{6}\ \text{Ci}$

  In the net reaction,, for the proton-proton cycle in the Sun, the neutrinos )li(;dkmk9 o cescape from the Sun wiikl; o9( mckd)th 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 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 abzc vn,,tf;3)w1myv4mpi(xb e9 d/ k ykout $1400\ \text{W/m}^2$. 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 evolution, may6ukb*hy h* r3 ;a2n).p7xfjk*unjmqm 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 con 4.1lki qj8s futt9o*itains 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 Chernobyl in 1986,6b; .n7rs+z il(r voo(hjr v,dd,mc 2n $2.0 \times 10^7\ \text{Ci}$ 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 prqr c4.pb2 b 2:rhl:ain the reaction $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. What is the Q-value for this reaction? Q =    MeV

  A $1.0-\mu\text{Ci}\ _{55}^{137}\text{Cs}$ source is used for 2.0 hours by a 75-kg student in a physics lab. Radioactive $_{55}^{137}\text{Cs}$ decays by $\beta^-$ decay with a half-life of 30 years. The average energy of the emitted betas is about 190 keV per decay. The $\beta^-$ decay is quickly followed by a $\gamma$ ray with an energy of 660 keV. Assuming the student absorbs all emitted energy, what effective dose (in rem) is received during lab? dose $\approx $    $ \times 10^{-5}\ \text{rem}$

  A large amount of $_{38}^{90}\text{Sr}$ was released during the Chernobyl nuclear reactor accident in 1986. The $_{38}^{90}\text{Sr}$ enters the body through the food chain. How long will it take for 90% of the $_{38}^{90}\text{Sr}$ released during the accident to decay? See Appendix B.$\approx $    y

Three radioactive sources have the same activity, 25 mCi. Source A emits 1.0-o)kl y 8 d,3hxlz1rw9(t (hfwnMeV orzn h f1 w,tllkw)( (x83dyh9$\gamma$ rays, source B emits 2.0-MeV $\gamma$ rays, and source C emits 2.0-MeV alphas. What is the relative danger of these sources?

  A 70-kg patient is to be given a medical test involving the ingestlqabaw+g r- hvl qzxr u(8 /o:wp1m63 4znu:x)ion 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 $    $\ \text{mCi}$