Fill in the missing p g mr+ 3m)+k8vcsng4auarticles 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;)w:ec.owy2tc,i52on sktoh projectiles 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 p.7isq63ljz. nqu*ufr ys(6f$\beta^+$ 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 fissiots qflhncy,0k 5)(up1 n appears in the form of thermal energy - but the thermal enerush lnf5,k0qtcy p1( )gy of what?

The energy from nuclear fission appearu;a ym+9axl;u, ju aw6s in the form of thermal energy - but the thermu auxy ;+uj;a w9m6l,aal energy of what?

Why can't uranium be enriched by chem9qv .hir7 smzte*m q.) laxu39ical means?

How can a neutron, with practically no kinetic energy, excite a nuc19 mpsla x)qcq:p-n7kleus to the extent sh7 kp 1-xlacmq)p:n9sqown in (Fig. Below)?

Why would a porous block of uranium be more likely to explode if ke3 3u 4wi+4owo-) 9a0rs tlids tk50afdh.oppxpt under water rather t9ud+ow4-s ih) t33f0wpa 0at.5s p kdro4xoi lhan in air?

A reactor that uses highly enriched uranium can use ordinary water (inste/fse yt0) mxj32a8 jfcad of heavy water) as a moderator and still have a self-sustaining chain reaction. Explamfst/f82 x3 yajje)c 0in.

Why must the fission process release neutrons if it is to be usr9)s k+kkcek,eful?

Discuss the relative merits and disadvantages, ij 6; m;zd;2i3g gt+rcdzimc:bncluding pollution and safety, of power generation by fossil fuels, nuclear fir; d; tz6g;dm3ibmci +gc2z: jssion, and nuclear fusion.

What is the reason for the "secon z7zla;i; * zwj:*nmnzdary system" in a nuclear reactor, (Fig. Below)? That is, why is the water heated by the fuel in a nuclear znw zzzl; m*7*ia j:n;reactor not used directly to drive the turbines?

Why are neutrons released inmbv hw p2.66 lfqe,5,kuvcd p9 a fission reaction?

Why do gamma particles pepj. bu66bg0wcsfyxa) 51 9ds tnetrate matter more easily than beta particles do?

A higher temperature is required for deuterium-deuterium ignition than for m9r zr.char68 u95m r caemg6s;-evp9deuterium-tritiumau9 reh8rccpz;mmr9 r.ema56s9 gv 6 -. Explain.

Light energy emitted by the Sun and stars 5 5yh fe*usn-rrzix:7comes from the fusion process. What conditions in the interior of stars make this poss 5yirr:f5hxusze -7*nible?

How do stars, and our Sun, maintain confinement of the plasm v0;c+.tmznp t 8hksn8a for fusion?

What is the basic difference between fission rzmja;y yi 05p p0ki:gkv9acc :l*h/1and fusion?

People who work around metals thau1)fyfb fjd2fhj3/6c1 )ej nnmld: e (t 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 wou(f yjfj hem dn)fjn: 2efb61l/)d 3c1rking, and against machining the metal. Why?

Why is the recommended maximum radiation dose higher for womr03xhj;;cn aben beyond the child-bearing age than for younger women? ;;03 anchbjrx

Radiation is sometimes used to sterilize medical sxw-) uwb o1*t hig+qk +ftb(5rp)zqe0upplies and even food. Explain how it workswu(g r5-f b)bhkipw+t )*z0o+qx1 eqt.

What is the difference between absorbed dose and effective dose? What are thekj(w*y9t 4fe0yr/fiy SI units e r*/ft0yykf (jwy9 4ifor each?

How might radioactive tracers be used to find w;qa24cpqa 8l4m gcj9 a leak in a pipe?

Natural aluminum is allrvlk 6uj3lz4(o 7pqy* $_{13}^{27}\text{Al}$. 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 reactimy2 onzyz/5+ lusgn c+b+.vwm,5n 0akgiz3d2on $_{1}^{2}\text{H} + _{1}^{2}\text{H} \to _{2}^{3}\text{He} + \text{n}$ 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 tsc3r f7hp-s)yhe reaction $_{5}^{10}\text{B} + \text{p} \to _{3}^{7}\text{Li} + \alpha$.    MeV

  (a) Can the reaction kd+w0n:fhla y92+ q hr$_{11}^{23}\text{Na} + \text{d} \to \text{n} + _{12}^{24}\text{Mg}$ 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 reactiong rs/+0 h ga9mq6xl -b;qhx5ee $_{3}^{7}\text{Li} + \text{p} \to _{2}^{4}\text{He} + \alpha$ 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 t;0 wd f9ezjte,he "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 products of the rh/f wnrf/( t8ko*8eu7k g r+*bc5 zhpgeaction $_{6}^{12}\text{C} + \text{d} \to _{7}^{13}\text{N} + \text{p}$ 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" nucleau)e0- .0r,cqz lw xhoxr 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" nucl(,cw)frd::r(o jyr i sear 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 fol3fo/5u jorkh/ fzk4esa0akv pd(1 /k6lowing 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 fissim.zd. ad ;2ph+0x dhuton 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* 0:*pv e(vtq +vyr;rtvqkq)d the fission reaction of Eq. 31-4? (The masses of 0tvk*y r*e)qr; tqv:dp +v q(v$_{56}^{140}\text{Ba}$ and $_{36}^{92}\text{Kr}$ are 140.914411 u and 91.926156 u, respectively.) Q =    MeV

  How many fissions take place per sjd:k:cx c:i40 :ac- y p1ebivtecond in a 200-MW reactor? Assume 200 MeV is released per fission. Pp:iv1accb:t: 4x jc d kei-:y0 =    $\times 10^{13}\ \text{reactions/s}$

  The energy produced by a lp5h:hqftgi )7o)sx vkl 9 2i0j+2ubzfission reactor is about 200 MeV per fission. What fraction of the resto 2ihv il2qs 9)75 bp 0zfxl:hj+uk)gt mass of a $_{92}^{235}\text{U}$ nucleus is this? The ratio is about $\approx 1 : $   

  Consider the fissionc .rrtc+p1tm6( 2rbbn reaction $_{92}^{235}\text{U} + \text{n} \to _{51}^{133}\text{Sb} + _{41}^{98}\text{Nb} + ?\text{n}$.
(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 nig uno.dyldq0sl56ux +7q+4 oxjkg ,4ycht, in a typical house 4gnl+d+.u o ko,u7cy065y ldx4x qjsqis 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 of3;-v w.cm)ugy31x2-oo gapc9 gjbnk nle: 4yk $_{92}^{235}\text{U}$ is required to operate a 650-MW reactor for 1 yr? Assume 40% efficiency. The initial mass is $\approx $    $\ \text{kg}$

  Assuming a fission oze2jrc6 k)h zi3-x; bbf $_{92}^{235}\text{U}$ 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 sta hmxd9ilxu + dzn6o0 kc9/yv/)r where the temperature isn / mkody uh069 /9)i+vdxzxlc $2 \times 10^7\ \text{K}$?
KE =    $ \times 10^{-16}\ \text{J}$
KE =    eV

  Calculate the energy released5u,vi q) ech+i in the fusion reaction $_{1}^{2}\text{H} + _{1}^{3}\text{H} \to _{2}^{4}\text{He} + \text{n}$ is    MeV.

  Calculate the energy released when two deuterium nuclei fuse to fo1p g9zqpuo :8-btdm9 brm $_{2}^{3}\text{He}$ with the release of a neutron is    MeV.

  Verify the Q-value stated for each of the relmjygw3- 1k.p actions 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 reactiy i ,mio 3kga1(r5jv4jf 1b;bbons of Eqs. 31-8a, b, and c. Compare to thjb rg fyi5ambbv;3(oj k,141ie energy 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 rel:nzupnnx-y: u3 6zje) eased when $_{92}^{238}\text{U}$ absorbs a slow neutron ($KE \approx 0$) and becomes $_{92}^{239}\text{U}$? Q =    MeV

  If a typical house requiresnzun 5e3lc:bt1 s4 vsqb.+:un 950 W of electric power on average, what minimum amount :zt1 4e.3bbn5nsl:snu uvcq+ of deuterium 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 oflai81m)h8al (kawcz 70icf* 8fpc(z kf 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*kygi)ke cc-pj8w * qoan ffv/up :2(i)tm+ ;l. Estimate how much water, for fuel, would be needed peu*ag) ceif pikq:-nw2o;(/)pl cm+kj 8 y*tf vr hour 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 dmh3ypy8-cedu-r,r++ c n1au its natural deuterium is used in t -e c-1ndyar+uucm drp,3+yh 8he fusion reaction of Eq. 31-8a? Compare 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 of massive stars is believed to be due to the carbon cycle ( *xpi*)*czu ejsee text). (a) Show that nj *iz*ex*c pu)o 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 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 f n47a-9pqs yev:. f 4 fw0byn71wbagdcirst reaction of the carbon cycle to that wfag 44-qnwf:dcn7b a719v0s by.pyefor 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 k 1 an3*7dm vu81dx/vi9adg:av)ot ik$\gamma$ rays in a short period would be lethal to about half the people subjected to it. How many grays is this?    $Gy$

  Fifty rads of $\alpha$-particle radiation is equivalent to how many rads of X-rays in terms of biological damage?    rad

  How many rads of slow neutrons will do as much biological damage as 75 rads a,:7vlduo 9ew2yvok 5of fast neutroowv9y5 kevu ,dlao:2 7ns?    rad slow neutrons

  How much energy is deposited in the body of a 65-kg 0yse61jhj3 nad 7vs0tadult exposed to a 2.0-Gy dose? 1jvnd es0sa306h7jty    $J$

  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(7ou,.l l lhoc radiation therapy in which protons with an energy of 1.2 MeV are incident on a , u.h lc(ol7lo0.25-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 l2d)o a9h-q /wzin sa2$_{15}^{32}\text{P}$ (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 p4( oqd32ztm1ffldq0v roduce one ion pair in air. Show that this is consistent with fz203o(4dmvt qq1l d fthe 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 zwsts+e2ls0i (aipc snt,203w4rq 1g$1.00-\mu\text{Ci}\ _{6}^{14}\text{C}$ source?    $\times 10^{-10}\ \text{kg}$

  Huge amounts of radioav j cjhxxzn-p) 5(2f1dctive $_{53}^{131}\text{I}$ 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 activity oszj9 l,q 8ybtalnja)49s j*,rf 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 swud00 d2bzv8ilefbb.+ 0(qxtransitions in free protons in a 1.000-T field..0z bbx(+qsbi2 8 vdflu we0d0 In what region of the spectrum does it lie? c =    $m$

  J. Chadwick discovered the neutron by bombarding 4yv8ktnh8h5bb -d8mq $_{4}^{9}\text{Be}$ 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 2,u))a ho0ce,b8 ifp. v ulsdugiven in keV. Determine the conversion factor from kelvins to keVulps i 2,)d,80fhoba vcuu.)e using, as is 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 diffusion of thh*b6 dkj .j2vme 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 m3tcl3u :zrd4 x:dcf 4d6yc,a mrad of X-rays xzf, 44adu:mtr :36ycdclc3 dand $\gamma$ 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 es3etip1nvp9 j fwv)5t 9lvbw13e ;b,nvtimate of the total deuterium in the Earth's oceans and estimate the total energy released if all of it were used in fusion reacwv f1bn9tj19 ln,3 e; i pwb)5vvtve3ptors.

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 propf f-z x4 .ivg:5a8w8s;dvyn eczl0*w duce 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 inh3y )w ilw axh3) f+zobku;:3w the Sun, the neutrinos escape from the Sun with energy of about 0.5 MeV. The remaining energy, 26.2kyo x+a3:)lh3 i fwhb)w3wzu; 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 thk k).x3b 9*qc :ptpm1.ugvy uhe 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 of evolution, may bojaqd.k d6(7pd6( pze egin 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 body3xwtui-q+b m7t 7dc :z 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 Chernobyl in 1e2+.bhku s bg1986, $2.0 \times 10^7\ \text{Ci}$ 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 ca :( aqg.7bjkw d72eqjsn burn helium 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 achum0x 4 74jxootivity, 25 mCi. Source A emits 1.0-MeVuj h 4o0xox7m4 $\gamma$ 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 h/ w9v-eszh3x 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 $    $\ \text{mCi}$