Fill in the missing particles or nuclei:vtgb3,uu*h/vpulfb0t ( f e88
(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 producing nucl* sc l:)kr/xsh.day+be yeusknf 5+()ear 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 fragment4 qs lyfholi6.) ai41ss $\beta^+$ 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 the form of thermal energ/zbh(q ,*)g*uju*li fqup)lujb epkk 3e 72m6y - but the thermal energy ,ujulqpm6*keqljgfbz7/3))up ei (*2* u hbk of what?

The energy from nuclear fission appears in the form of thermal energy - but tok+tf74c/ 5 ,bznbpil he thermalp4f t,+biobl5 zcn7k / energy of what?

Why can't uranium be enriched by chemical meansbmlza; heefsks3 8xa7 q6e*+)/ -dsgu?

How can a neutron, with practically no kinetic energy, excite a nucleus to the 5y j4gicei., kextent shown in (Fig. y i,kgj.c4i e5Below)?

Why would a porous block of uranium be more likely to explode if kept un r5:n.q96d0fzzhgia vder water rather than ingfd.5a0 vz 6i rn9:zhq air?

A reactor that uses highly enriche* 25 dlmea5grnvdi -1mi2v)vdfp w1n -d uranium can use ordinary water (instead of heavy water) as a moderator and still have a self-sustaining chain reaction. 5 d1e*gdvdn-m2prv1ml vii fw- n) a25Explain.

Why must the fission process release neutrons if it is tog8qe0te ho/:/lkmk:xmz 2q(qtr56i d be useful?

Discuss the relative merits and disadvantages, including polluhkgle96k8 7 +vnkqa- dtion and safety, of power generation by fossil fuels, nucl8-n k+klvekqa76dgh 9ear fission, and nuclear fusion.

What is the reason for the "secondary system" in a nuclear reg z/(:d bv9tdt,li,t jk im8i/actor, (Fig. Below)? That is, why is the water he tbgt /m :,d(di9ikz8l v,tij/ated by the fuel in a nuclear reactor not used directly to drive the turbines?

Why are neutrons released in a fission reactfvz,ps/8+ cz+6telyjb g(rdua1h, k-ion?

Why do gamma particles penetrate matter mo.;t 95c;qqr(lwrk-jze+vh/ /p tcsc .neda2b re easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignw 3w pe3byv2)lw+e5h qition than for deuteribv qpewwl+)5332 ywehum-tritium. Explain.

Light energy emitted by the Sun and strpw*t4vwb vuqv y6-(p nul5+3 ars comes from the fusion process. What conditions in the interior of stars make this *pwu 6ntpr+bl w qvv45u3(-vypossible?

How do stars, and our Sun, maintain confinemenzb vp5(w,wl.v t of the plasma for fusion?

What is the basic difference between fission and fc9j3lh0t- ihq usion?

People who work around me 4 hvo(c*cs dp *b3tjn)y //xv0rldd1ktals that emit alpha particles are trained that there is little danger from proximity or even touching the material, but that they must take extreme precautions against ingesting it. Hence, there are strong rules against eating and drinking while wo/cn03*kovv4 y tcd s x*h(pdj)/1dblrrking, and against machining the metal. Why?

Why is the recommended maximum radiation dose higher for women beyond igt- ,6s8y)weh h. gwj3h,*th c-tz7 hn lum*fthe child-bearing age than for younger wil jt-hh)6ewhy,ug-.mn g c8tfhs,w7t h3 z**omen?

Radiation is sometimes used to sterilize medical suppliesch h3;y:g/byb and even food. Explain how it work/3 h;ybygh c:bs.

What is the difference between absorbed do;qqmpuzyt/hm31ks 8+ 9n hqt.se and effective dose? What are the SI units ;q m npts+kytu.mz9q1q3h8/hfor each?

How might radioactive tracers be used to fb 87x.igfml: zind a leak in a pipe?

Natural aluminum is all l 4 z5oswcs;t ctd.,7g$_{13}^{27}\text{Al}$. 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 reaher ,rdvx* k/0ction $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 1mo sdgs//vovsfvj5m g3 29* l(or energy input required) for the reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction 9t4aqv - 3fvrlg.a*h is/.ss g$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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(jjhy7jo 7pk ubha*36 $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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" .h 58x7zb jnc;ajmsva v-s81 freaction $_{2}^{4}\text{He} + _{4}^{9}\text{Be} \to _{6}^{12}\text{C} + \text{n}$. Q =    MeV

  Calculate the total kinetic energy of the product;o(brrzg;s5m+9.y c f3 tttz4bj hqd)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 "strippi/cybm +pbdva4up :2,cc f1.yog 3m 8ssng" 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-uh-3u+-b jfo ghyh/x9 wp" 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 followil ghmy0;d lq bmf.(tcyx,l2*,ng nuclear 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 in the jh:8u k-wi-nh 7g8nonfission 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/1tmhda/ vo4 :2ndhzu25hsni. 31-4? (The masses of /nt4/hzd 2u1a:mh son25 v hid$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per7rgo. la lljm 2sc/52l second in a 200-MW reactor? Assume 200 MeV is released per fission.r/c2 l.l mljl2 s5oa7g P =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a fission reactor is about 200 MeV mdnw8*mza9- nper fission. What fraction of the resta9mz 8w-*d mnn mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fission reaxu ;qlhvoi :/666sjxwir u8gs a/v8*gction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 typical45m u etksru su a d7aoak2zxcq387571 house is 950 W. What initial mass 1csam7oq8 eakxk47d7zusr5 u32 5 tu aof $_{92}^{235}\text{U}$ 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 ofix c7pb3t,+spk(l mm/ $_{92}^{235}\text{U}$ 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 euecr yk m0 6v5w4 ls*g2dv4p7$_{92}^{235}\text{U}$ 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 center of a sta8h6dt1 wpx1h keau dihbb7:zoz4 h2* )r)/iqvr where the temperature ie b khua zx*d/rh tbp i:z7h vhqi)o4161d82)ws $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy rel9np0+nqq b6n8 24h zkxshux3s 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 r u,ag*40c lxsqeleased 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 thgz rxtv98qs( t;m.t ho k1-pn-rlp3g0e 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 re0xsbfmxjv :9pu .mjc)px 9; d2lease per gram of fuel for the reactions of Eqs. 31-8a, b, and c. Compare to the enps.df9mm9)j0bu;vx2x :xp jcergy release per gram of uranium in fission.
31-8a =    $ \times 10^{23}\ \text{MeV/g}$
31-8b =    $\times 10^{23}\ \text{MeV/g}$
31-8c =    $ \times 10^{24}\ \text{MeV/g}$
Uranium fission =    $ \times 10^{23}\ \text{MeV/g}$

  How much energy is rele-0 9)ve l owms)tesm;nased 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 avera,n emfeu/v q, 77pg+wx*a0xyvge, what minimum amount of deuterium fuel would have to be used in a year gf,mnq ey*xa70 7,pevv/+ uwxto supply these electrical needs? Assume the reaction of Eq.31- 8b.    g

Show that the energies carried offsd/ x/feq s1c4 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" 7 ;sj73nnnm3xt3ngt - o/ xvfmreactions, Eqs. 31-8a and b. Estimate how much water, for fuel, would be needed per hmnj 7xtn- s7t;x 3m vfn/3no3gour to run a 1000-MW reactor, assuming 30% efficiency. $\approx$    $kg/h$

  How much energy (J) is contained in 1.00 kg of water if its natural deuterium g* i:ff hxaclut8 .j5dr( 9*jhis used in the fusion reaction of Eq. 31-8a? Compare to the energy obtained from the burnid.*lh:5i*jh jtf(gr9c a8 ufxng 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 cawjq.hf2xd (6 crbon 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 energqhjf d. 6wc(x2y 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 the first reaction ofg+t ie).r7bh:ntt3q y the carbon cycle to that ti y)t3+nrgt :.eqhb7for 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 1u- /d ;wzqm)yro dwxnd(w693kv ju: p$\gamma$ 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 wec/cc c3j2)cij o),.1decymrill do as much biological damage as 75 rads of fast neucy.cmej /) 2e3coc1i)rcj, cdtrons?    rad slow neutrons

  How much energy is deposited in the body of a 6m)h 0n cy,q 6ktpcnro w,ry*;sc 553ob5-kg adult exposed to a 2.0-Gy dos5,0 rcm,6h)ns3k rncbcwyoqot5; py* e?    $J$

  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 undergointhxnzge /, w( y2bz* la10k,cvg radiation therapy in which protons with an energy of 1.2 MeV are incident on a 0.25-kg z (1hz,ge 20/c,n*w bkxavtyl 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 i 7;j3ct ty0qr/ ddp(r*y2hl)h0 smnd$_{15}^{32}\text{P}$ (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 to.oc-cy++,aw7 oj0 +etbaa jthis is consistent with the two defintoaaje t,+0. -oywaj7ccb+ + oitions 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 u (t v2ghonvl6,..lqha $1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioactihd7/uv x,h:x lhs :7aqve $_{53}^{131}\text{I}$ 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 haz*:rikc8o o/w s 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 transitionb 0pq7p1 zs*w+c4h qehs in free protons in a 1.000-T field. In what region of the spectrum does it lie? ccqzb 0w ph+s1 e74hp*q =    $m$

  J. Chadwick discovered the neutron by bombard36f,vf; p+d b-ciu;6 kqu+q4iw tcngfing $_{4}^{9}\text{Be}$ 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 conver1f)abugrc 3/bsion factor from kelvins to keV using, as is common in thu)b c1bg3r/afis field, $KE = kT$ without the factor $\frac{3}{2}$. K =    $ \times 10^{-5}\ \text{keV/K}$

  One means of enriching uranh szbixq;abwc:(6t(0 lfvp p+ ,cq4+ 9cku)pwium 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 background radiation consists of 21 mrad j1vhfo;i 5 3jbof X-ray1jov5 b;fhj3i s 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 rough est7*uw uls i31wgimate of the total deuterium in the Earth's oceans and estimate the total 7*uwi1ws u3gl 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 pr br2c.k+lft:e. po n8koduce 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-protone yxx 3g+xmqo34x d3th gyb716 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 calc4x1gqt33yx 76 hg3modexx+by ulate 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 al2aele8*j3rlz)siv tht) ++s8tbn q7 t 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 of evolution, may begin to fuac:;5z2coeb0 .s vri wse 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 5furjlh w c) cg:k5glb5b (roo* :h;m(contains 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 Cu.rrj )t0k4a7ub s 8rphernobyl 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 he5wp7k5 qhj9kz lium in the reaction $3\ _{2}^{4}\text{He} \to _{6}^{12}\text{C} + \gamma$. What is the Q-value for this reaction? Q =    MeV

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

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

Three radioactive sources have the same activity, 25 mCi. Source A emits 1.xulmy:w ) m9*0lmtgqk+6o5pp9f fp - b0-MeV m9)gu +-mkf:5my w0xpp6* 9qolpbftl $\gamma$ 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 involvw9iw sksjt fac6182**onfi 4g ing 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 $    $\ \text{mCi}$